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Sample records for 13c nmr ft-ir

  1. Interactions of D-cellobiose with selected chloride salts: A 13C NMR and FT-IR study

    NASA Astrophysics Data System (ADS)

    Amarasekara, Ananda S.; Wiredu, Bernard

    2016-04-01

    The interactions of cellulose model compound D-cellobiose with chloride salts of Zn2 +, Ca2 +, Li+, Sn2 +, La3 +, Mg2 +, K+ and NH4+ were evaluated by measuring the 13C NMR chemical shift changes (Δδ) of the disaccharide due to the addition of salts in D2O. The KCl and NH4Cl showed similar Δδ changes due to interactions only with the Cl- anion. Whereas other chloride salts showed interactions with both cation and anion. Among these salts the total interactions are in the order: Zn2 + > Sn2 + > Li+ > Ca2 + ~ La3 + > Mg2 +. The FT-IR spectra of D-cellobiose-chloride salt 1:2 mixtures also indicate that KCl and NH4Cl interacts similarly with D-cellobiose in the solid state.

  2. Solid state 13C NMR and FT-IR spectroscopy of the cocoon silk of two common spiders

    NASA Astrophysics Data System (ADS)

    Bramanti, Emilia; Catalano, Donata; Forte, Claudia; Giovanneschi, Mario; Masetti, Massimo; Veracini, Carlo Alberto

    2005-11-01

    The structure of the silk from cocoons of two common spiders, Araneus diadematus (family Araneidae) and Achaearanea tepidariorum (family Theridiidae) was investigated by means of 13C solid state NMR and FT-IR spectroscopies. The combined use of these two techniques allowed us to highlight differences in the two samples. The cocoon silk of Achaearanea tepidariorum is essentially constituted by helical and β-sheet structures, whereas that of Araneus diadematus shows a more complex structure, containing also β-strands and β-turns. Moreover, the former silk is essentially crystalline while the latter contains more mobile domains. The structural differences of the two cocoon silks are ascribed to the different habitat of the two species.

  3. The retrogradation properties of glutinous rice and buckwheat starches as observed with FT-IR, 13C NMR and DSC.

    PubMed

    Lian, Xijun; Wang, Changjun; Zhang, Kunsheng; Li, Lin

    2014-03-01

    The experiment was conducted to study the retrogradation properties of glutinous rice and buckwheat starch with wavelengths of maximum absorbance, FT-IR, (13)C NMR, and DSC. The results show that the starches in retrograded glutinous rice starch and glutinous rice amylopectin could not form double helix. The IR results show that protein inhabits in glutinous rice and maize starches in a different way and appearance of C-H symmetric stretching vibration at 2852 cm(-1) in starch might be appearance of protein. Retrogradation untied the protein in glutinous amylopectin. Enthalpies of sweet potato and maize granules are higher than those of their retrograded starches. The (13)C NMR results show that retrogradation of those two starches leads to presence of β-anomers and retrogradation might decompose lipids in glutinous rice amylopectin into small molecules. Glutinous rice starch was more inclined to retrogradation than buckwheat starch. The DSC results show that the second peak temperatures for retrograded glutinous rice and buckwheat starches should be assigned to protein. The SEM results show that an obvious layer structure exists in retrograded glutinous rice amylopectin.

  4. The spectroscopic (FT-IR, FT-Raman and 1H, 13C NMR) and theoretical studies of cinnamic acid and alkali metal cinnamates

    NASA Astrophysics Data System (ADS)

    Kalinowska, Monika; Świsłocka, Renata; Lewandowski, Włodzimierz

    2007-05-01

    The effect of alkali metals (Li → Na → K → Rb → Cs) on the electronic structure of cinnamic acid (phenylacrylic acid) was studied. In this research many miscellaneous analytical methods, which complement one another, were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance ( 1H, 13C NMR) and quantum mechanical calculations. The spectroscopic studies lead to conclusions concerning the distribution of the electronic charge in molecule, the delocalization energy of π-electrons and the reactivity of metal complexes. The change of metal along with the series: Li → Na → K → Rb → Cs caused: (1) the change of electronic charge distribution in cinnamate anion what is seen via the occurrence of the systematic shifts of several bands in the experimental and theoretical IR and Raman spectra of cinnamates, (2) systematic chemical shifts for protons 1H and 13C nuclei.

  5. Zn(II), Cd(II) and Hg(I) complexes of cinnamic acid: FT-IR, FT-Raman, 1H and 13C NMR studies

    NASA Astrophysics Data System (ADS)

    Kalinowska, M.; Świsłocka, R.; Lewandowski, W.

    2011-05-01

    The effect of zinc, cadmium(II) and mercury(I) ions on the electronic structure of cinnamic acid (phenylacrylic acid) was studied. In this research many miscellaneous analytical methods, which complement one another, were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance ( 1H, 13C NMR) and quantum mechanical calculations. The spectroscopic studies provide some knowledge on the distribution of the electronic charge in molecule, the delocalization energy of π-electrons and the reactivity of metal complexes. In the series of Zn(II) → Cd(II) → Hg(I) cinnamates: (1) systematic shifts of several bands in the experimental and theoretical IR and Raman spectra and (2) regular chemical shifts for protons 1H and 13C nuclei were observed.

  6. Experimental (FT-IR, FT-Raman, UV-Vis, 1H and 13C NMR) and computational (density functional theory) studies on 3-bromophenylboronic acid

    NASA Astrophysics Data System (ADS)

    Karabacak, M.; Kose, E.; Atac, A.; Sas, E. B.; Asiri, A. M.; Kurt, M.

    2014-11-01

    Structurally, boronic acids are trivalent boron-containing organic compounds that possess one alkyl substituent (i.e., C-Br bond) and two hydroxyl groups to fill the remaining valences on the boron atom. We studied 3-bromophenylboronic acid (3BrPBA); a derivative of boronic acid. This study includes the experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV-Vis) techniques and theoretical (DFT-density functional theory) calculations. The experimental data are recorded, FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase. 1H and 13C NMR spectra are recorded in DMSO solution. UV-Vis spectrum is recorded in the range of 200-400 nm for each solution (in ethanol and water). The theoretical calculations are computed DFT/B3LYP/6-311++G(d,p) basis set. The optimum geometry is also obtained from inside for possible four conformers using according to position of hydrogen atoms after the scan coordinate of these structures. The fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and parallel quantum solutions (PQS) program. 1H and 13C NMR chemical shifts are racked on by using the gauge-invariant atomic orbital (GIAO) method. The time-dependent density functional theory (TD-DFT) is used to find HOMO and LUMO energies, excitation energies, oscillator strengths. The density of state of the studied molecule is investigated as total and partial density of state (TDOS and PDOS) and overlap population density of state (OPDOS or COOP) diagrams have been presented. Besides, frontier molecular orbitals (FMOs), molecular electrostatic potential surface (MEPs) and thermodynamic properties are performed. At the end of this work, the results are ensured beneficial for the literature contribution.

  7. Application of Spectroscopic Techniques (FT-IR, 13C NMR) to the analysis of humic substances in volcanic soils along an environmental gradient (Tenerife, Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Rodriguez Rodriguez, Antonio; María Armas Herrera, Cecilia; González Pérez, José Antonio; González-Vila, Francisco Javier; Arbelo Rodríguez, Carmen Dolores; Mora Hernández, Juan Luis; Polvillo Polo, Oliva

    2010-05-01

    Andosols and andic soils are considered as efficient C-sinks in terms of C sequestration. These soils are usually developed from volcanic materials, and are characterized by a predominance of short-range ordered minerals like allophanes, imogolite and other Fe and Al oxyhydroxides. Such materials occur commonly associated with organic compounds, thus generating highly stable organo-mineral complexes and leading to the accumulation of a high amount of organic carbon. Spectroscopic methods like FT-IR and 13C NMR are suitable for the analysis of the chemical structure of soil humic substances, and allow identifying distinct functional groups and protein, lipids, lignin, carbohydrate-derived fragments. In this work we study the structural features of four soils developed on Pleistocene basaltic lavae in Tenerife (Canary Island, Spain), distributed along an altitudinal climatic gradient. The soil sequence comprises soils with different degree of geochemical evolution and andic character, including a mineral ‘Hypersalic Solonchak' (Tabaibal de Rasca), a slightly vitric ‘Luvic Phaeozem' (Los Frailes), a degraded and shallow ‘Endoleptic, fulvic, silandic Andosol' (Siete Lomas), and a well-developed and deep ‘Fulvic, silandic, Andosol' (Ravelo). Samples of the raw soil and humic and fulvic acids isolated from the surface horizons were analyzed. The results show a low content of organic carbon in the mineral soil, the inherited humin predominating, and a very high content of humic and fulvic acids in Andosols. The FT-IR and 13C NMR spectra of the raw soil samples show a low resolution, related to interferences from mineral complexes signals, particularly in soils with lower organic carbon content. 13C NMR shows a predominance of O-alkyl carbon (derived of carbohydrates) in andic soils, whereas O-alkyl and aromatic fractions are most evident in the mineral soil. The humic acids spectra are characterized by a dominance of alkyl and aromatic fractions with a high degree

  8. Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid.

    PubMed

    Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

    2015-02-01

    In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n=1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts ((1)H and (13)C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results. PMID:25448933

  9. Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid.

    PubMed

    Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

    2015-02-01

    In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n=1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts ((1)H and (13)C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

  10. Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid

    NASA Astrophysics Data System (ADS)

    Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

    2015-02-01

    In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

  11. Spectroscopic characteristic (FT-IR, FT-Raman, UV, 1H and 13C NMR), theoretical calculations and biological activity of alkali metal homovanillates

    NASA Astrophysics Data System (ADS)

    Samsonowicz, M.; Kowczyk-Sadowy, M.; Piekut, J.; Regulska, E.; Lewandowski, W.

    2016-04-01

    The structural and vibrational properties of lithium, sodium, potassium, rubidium and cesium homovanillates were investigated in this paper. Supplementary molecular spectroscopic methods such as: FT-IR, FT-Raman in the solid phase, UV and NMR were applied. The geometrical parameters and energies were obtained from density functional theory (DFT) B3LYP method with 6-311++G** basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned. Geometric and magnetic aromaticity indices, atomic charges, dipole moments, HOMO and LUMO energies were also calculated. The microbial activity of investigated compounds was tested against Bacillus subtilis (BS), Pseudomonas aeruginosa (PA), Escherichia coli (EC), Staphylococcus aureus (SA) and Candida albicans (CA). The relationship between the molecular structure of tested compounds and their antimicrobial activity was studied. The principal component analysis (PCA) was applied in order to attempt to distinguish the biological activities of these compounds according to selected band wavenumbers. Obtained data show that the FT-IR spectra can be a rapid and reliable analytical tool and a good source of information for the quantitative analysis of the relationship between the molecular structure of the compound and its biological activity.

  12. Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR (1H and 13C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine.

    PubMed

    Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

    2014-09-15

    The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, 1H and 13C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm(-1) and 4000-10 cm(-1), respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400 nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for 1H and 13C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, 1H and 13C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G** basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results.

  13. Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR (1H and 13C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine.

    PubMed

    Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

    2014-09-15

    The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, 1H and 13C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm(-1) and 4000-10 cm(-1), respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400 nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for 1H and 13C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, 1H and 13C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G** basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results. PMID:24813280

  14. Vibrational (FT-IR and FT-Raman), electronic (UV-Vis), NMR (1H and 13C) spectra and reactivity analyses of 4,5-dimethyl-o-phenylenediamine

    NASA Astrophysics Data System (ADS)

    Atac, Ahmet; Karaca, Caglar; Gunnaz, Salih; Karabacak, Mehmet

    2014-09-01

    The structure of 4,5-dimethyl-o-phenylenediamine (C8H12N2, DMPDA) was investigated on the basis of spectroscopic data and theoretical calculations. The sterochemical structure was determined by FT-IR, FT-Raman, UV, 1H and 13C NMR spectra. An experimental study and a theoretical analysis were associated by using the B3LYP method with Gaussian09 package program. FT-IR and FT-Raman spectra were recorded in the region of 4000-400 cm-1 and 4000-10 cm-1, respectively. The vibrational spectra were calculated by DFT method and the fundamental vibrations were assigned on the basis of the total energy distribution (TED), calculated with scaled quantum mechanics (SQM) method with Parallel Quantum Solutions (PQS) program. The UV absorption spectrum of the compound that dissolved in ethanol solution were recorded in the range of 190-400 nm. Total density of state (TDOS) and partial density of state (PDOS) of the DMPDA in terms of HOMOs and LUMOs were calculated and analyzed. Chemical shifts were reported in ppm relative to tetramethylsilane (TMS) for 1H and 13C NMR spectra. The compound was dissolved in dimethyl sulfoxide (DMSO). Also, 1H and 13C chemical shifts calculated using the gauge independent atomic orbital (GIAO) method. Mullikan atomic charges and other thermo-dynamical parameters were investigated with the help of B3LYP (DFT) method using 6-311++G** basis set. On the basis of the thermodynamic properties of the title compound at different temperatures have been carried out, revealing the correlations between heat capacity (C), entropy (S), enthalpy changes (H) and temperatures. The optimized bond lengths, bond angles, chemical shifts and vibrational wavenumbers showed the best agreement with the experimental results.

  15. Spectroscopic (FT-IR, FT-Raman, 1H, 13C NMR, UV/VIS), thermogravimetric and antimicrobial studies of Ca(II), Mn(II), Cu(II), Zn(II) and Cd(II) complexes of ferulic acid

    NASA Astrophysics Data System (ADS)

    Kalinowska, M.; Piekut, J.; Bruss, A.; Follet, C.; Sienkiewicz-Gromiuk, J.; Świsłocka, R.; Rzączyńska, Z.; Lewandowski, W.

    2014-03-01

    The molecular structure of Mn(II), Cu(II), Zn(II), Cd(II) and Ca(II) ferulates (4-hydroxy-3-methoxycinnamates) was studied. The selected metal ferulates were synthesized. Their composition was established by means of elementary and thermogravimetric analysis. The following spectroscopic methods were used: infrared (FT-IR), Raman (FT-Raman), nuclear magnetic resonance (13C, 1H NMR) and ultraviolet-visible (UV/VIS). On the basis of obtained results the electronic charge distribution in studied metal complexes in comparison with ferulic acid molecule was discussed. The microbiological study of ferulic acid and ferulates toward Escherichia coli, Bacillus subtilis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris was done.

  16. Monomeric and dimeric structures analysis and spectroscopic characterization of 3,5-difluorophenylboronic acid with experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Asiri, Abdullah M.; Kurt, Mustafa

    2014-01-01

    The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C6H3F2B(OH)2) were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C NMR spectroscopic techniques. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase and 1H and 13C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200-400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. 1H and 13C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.

  17. Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid

    NASA Astrophysics Data System (ADS)

    Świsłocka, Renata

    The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and 1H and 13C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris.

  18. Spectroscopic (FT-IR, FT-Raman, 1H- and 13C-NMR), theoretical and microbiological study of trans o-coumaric acid and alkali metal o-coumarates.

    PubMed

    Kowczyk-Sadowy, Małgorzata; Świsłocka, Renata; Lewandowska, Hanna; Piekut, Jolanta; Lewandowski, Włodzimierz

    2015-02-13

    This work is a continuation of research on a correlation between the molecular structure and electronic charge distribution of phenolic compounds and their biological activity. The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of trans o-coumaric (2-hydroxy-cinnamic) acid was studied. We investigated the relationship between the molecular structure of the tested compounds and their antimicrobial activity. Complementary molecular spectroscopic techniques such as infrared (FT-IR), Raman (FT-Raman), ultraviolet-visible (UV-VIS) and nuclear magnetic resonance (1H- and 13C-NMR) were applied. Structures of the molecules were optimized and their structural characteristics were calculated by the density functional theory (DFT) using the B3LYP method with 6-311++G** as a basis set. Geometric and magnetic aromaticity indices, atomic charges, dipole moments and energies were also calculated. Theoretical parameters were compared to the experimental characteristics of investigated compounds. Correlations between certain vibrational bands and some metal parameters, such as electronegativity, ionization energy, atomic and ionic radius, were found. The microbial activity of studied compounds was tested against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris and Candida albicans.

  19. Synthesis, X-ray crystallography, spectroscopic (FT-IR, 1H &13C NMR and UV), computational (DFT/B3LYP) and enzymes inhibitory studies of 7-hydroximinocholest-5-en-3-ol acetate

    NASA Astrophysics Data System (ADS)

    Ahmad, Faheem; Parveen, Mehtab; Alam, Mahboob; Azaz, Shaista; Malla, Ali Mohammed; Alam, Mohammad Jane; Lee, Dong-Ung; Ahmad, Shabbir

    2016-07-01

    The present study reports the synthesis of 7-Hydroximinocholest-5-en-3-ol acetate (syn. 3β-acetoxycholest-5-en-7-one oxime; in general, steroidal oxime). The identity of steroidal molecule was confirmed by NMR, FT-IR, MS, CHN microanalysis and X-ray crystallography. DFT calculations on the titled molecule have been performed. The molecular structure and spectra interpreted by Gaussian hybrid computational analysis theory (B3LYP) are found to be in good correlation with the experimental data obtained from the various spectrophotometric techniques. The vibrational bands appearing in the FTIR are assigned with great accuracy using harmonic frequencies along with intensities and animated modes. Molecular properties like HOMO-LUMO analysis, chemical reactivity descriptors, MEP mapping, dipole moment and natural atomic charges have been presented at the same level of theory. Moreover, the Hirshfeld analysis was carried out to ascertain the secondary interactions and associated 2D fingerprint plots. The percentages of various interactions are pictorialized by fingerprint plots of Hirshfeld surface. Steroidal oxime exhibited promising inhibitory activity against acetylcholinesterase (AChE) as compared to the reference drug, tacrine. Molecular docking was performed to introduce steroidal molecules into the X-ray crystal structures of acetylcholinesterase at the active site to find out the probable binding mode. The results of molecular docking admitted that steroidal oxime may exhibit enzyme inhibitor activity.

  20. Spectroscopic (FT-IR, FT-Raman, UV, 1H and 13C NMR) profiling and theoretical calculations of (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]hydrazinecarboxamide: An anticonvulsant agent

    NASA Astrophysics Data System (ADS)

    Haress, Nadia G.; Govindarajan, Munusamy; AL-Wabli, Reem I.; Almutairi, Maha S.; Al-Alshaikh, Monirah A.; Al-Saadi, Abdulaziz A.; Attia, Mohamed I.

    2016-08-01

    Vibrational characteristics of the anticonvulsant agent, (2E)-2-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]hydrazinecarboxamide ((2E)-IPHC) have been investigated. The computational data are obtained by adopting ab initio Hartree-Fock (HF) and DFT/B3LYP/6-31 + G(d,p) methods. The most stable conformer is identified by a potential energy scan. The optimized geometrical parameters indicated that the overall symmetry of the most stable conformer is CS. Atoms in molecules (AIM) analysis is contained out and the chemical bondings between the atoms are as characterized. Mulliken atomic charges and simulated thermo-molecular (heat capacity and enthalpy) characteristics of the (2E)-IPHC molecule also have been analyzed. The magnitude of the molecular electrostatic potential (MEP) of oxygen, hydrogen, and nitrogen atoms as well as phenyl and imidazole rings in the title molecule were investigated along with their contribution to the biological activity. The energy gap between HOMO and LUMO orbitals has been found to be 5.1334 eV in the gaseous phase. Excitation energies, oscillator strength and wavelengths were computed by the time-dependent density function theory (TD-DFT) approach. Predicted wavenumbers have been assigned and they are consistent with the experimental values. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the (2E)-IPHC molecule were computed by the gauge independent atomic orbital (GIAO) method and were compared with the experimental results.

  1. Molecular structure, spectral investigation (1H NMR, 13C NMR, UV-Visible, FT-IR, FT-Raman), NBO, intramolecular hydrogen bonding, chemical reactivity and first hyperpolarizability analysis of formononetin [7-hydroxy-3(4-methoxyphenyl)chromone]: A quantum chemical study

    NASA Astrophysics Data System (ADS)

    Srivastava, Anubha; Mishra, Rashmi; Kumar, Sudhir; Dev, Kapil; Tandon, Poonam; Maurya, Rakesh

    2015-03-01

    Formononetin [7-hydroxy-3(4-methoxyphenyl)chromone or 4‧-methoxy daidzein] is a soy isoflavonoid that is found abundantly in traditional Chinese medicine Astragalus mongholicus (Bunge) and Trifolium pretense L. (red clover), and in an Indian medicinal plant, Butea (B.) monosperma. Crude extract of B.monosperma is used for rapid healing of fracture in Indian traditional medicine. In this study, a combined theoretical and experimental approach is used to study the properties of formononetin. The optimized geometry was calculated by B3LYP method using 6-311++G(d,p) as a large basis set. The FT-Raman and FT-IR spectra were recorded in the solid phase, and interpreted in terms of potential energy distribution (PED) analysis. Density functional theory (DFT) is applied to explore the nonlinear optical properties of the molecule. Good consistency is found between the calculated results and observed data for the electronic absorption, IR and Raman spectra. The solvent effects have been calculated using time-dependent density functional theory in combination with the integral equation formalism polarized continuum model, and the results are in good agreement with observed measurements. The double well potential energy curve of the molecule about the respective bonds, have been plotted, as obtained from DFT/6-31G basis set. The computational results diagnose the most stable conformer of formononetin. The HOMO-LUMO energy gap of possible conformers has been calculated for comparing their chemical activity. Chemical reactivity has been measured by reactivity descriptors and molecular electrostatic potential surface (MEP). The 1H and 13C NMR chemical shifts of the molecule were calculated by the Gauge including atomic orbital (GIAO) method. Furthermore, the role of CHsbnd O intramolecular hydrogen bond in the stability of molecule is investigated on the basis of the results of topological properties of AIM theory and NBO analysis. The calculated first hyperpolarizability shows

  2. Spectroscopic (FT-IR, FT-Raman and NMR) and computational studies on 3-methoxyaniline

    NASA Astrophysics Data System (ADS)

    Sivaranjini, T.; Periandy, S.; Govindarajan, M.; Karabacak, M.; Asiri, A. M.

    2014-01-01

    In this work, the molecular structure, vibrational, UV and NMR spectra of 3-methoxyaniline (abbreviated as 3MOA, C7H9NO) were studied. The FT-IR and FT-Raman spectra were recorded. The ground-state molecular geometry and vibrational frequencies were calculated by using the Hartree-Fock (HF) and density functional theory (DFT)/B3LYP methods and 6-311++G(d, p) as a basis set. The fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Comparison of the observed fundamental vibrational frequencies of 3MOA with calculated results by HF and DFT methods indicates that B3LYP is superior to HF method for molecular vibrational problems. The difference between the observed and scaled wavenumber values is very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. A study on the Mulliken atomic charges, the electronic properties were performed by time-dependent DFT (TD-DFT) approach, Frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed and compared with methoxybenzene and aniline. The electric dipole moment (μ) and the first hyperpolarizability (β) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the 3MOA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  3. Solid State FT-IR and (31)P NMR Spectral Features of Phosphate Compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solid-state spectroscopic techniques, including Fourier transform infrared (FT-IR) and solid-state 31P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopies, are powerful tools for evaluating metal speciation and transformation mechanisms of P compounds in the environment. Studie...

  4. Structure analysis and spectroscopic characterization of 2-Fluoro-3-Methylpyridine-5-Boronic Acid with experimental (FT-IR, Raman, NMR and XRD) techniques and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Alver, Özgür; Dikmen, Gökhan

    2016-03-01

    Possible stable conformers, geometrical molecular structures, vibrational properties as well as band assignments, nuclear magnetic shielding tensors of 2-Fluoro-3-Methylpyridine-5-Boronic Acid (2F3MP5BA) were studied experimentally and theoretically using FT-IR, Raman, (CP/MAS) NMR and XRD spectroscopic methods. FT-IR and Raman spectra were evaluated in the region of 3500-400 cm-1, and 3200-400 cm-1, respectively. The optimized geometric structures, vibrational wavenumbers and nuclear magnetic shielding tensors were examined using Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. 1H, 13C NMR chemical shifts were calculated using the gauge invariant atomic orbital (GIAO) method. 1H, 13C, APT and HETCOR NMR experiments of title molecule were carried out in DMSO solution. 13C CP/MAS NMR measurement was done with 4 mm zirconium rotor and glycine was used as an external standard. Single crystal of 2F3MP5BA was also prepared for XRD measurements. Assignments of vibrational wavenumbers were also strengthened by calculating the total energy distribution (TED) values using scaled quantum mechanical (SQM) method.

  5. Molecular structure, vibrational spectral assignments (FT-IR and FT-RAMAN), NMR, NBO, HOMO-LUMO and NLO properties of O-methoxybenzaldehyde based on DFT calculations

    NASA Astrophysics Data System (ADS)

    Vennila, P.; Govindaraju, M.; Venkatesh, G.; Kamal, C.

    2016-05-01

    Fourier transform - Infra red (FT-IR) and Fourier transform - Raman (FT-Raman) spectroscopic techniques have been carried out to analyze O-methoxy benzaldehyde (OMB) molecule. The fundamental vibrational frequencies and intensity of vibrational bands were evaluated using density functional theory (DFT). The vibrational analysis of stable isomer of OMB has been carried out by FT-IR and FT-Raman in combination with theoretical method simultaneously. The first-order hyperpolarizability and the anisotropy polarizability invariant were computed by DFT method. The atomic charges, hardness, softness, ionization potential, electronegativity, HOMO-LUMO energies, and electrophilicity index have been calculated. The 13C and 1H Nuclear magnetic resonance (NMR) have also been obtained by GIAO method. Molecular electronic potential (MEP) has been calculated by the DFT calculation method. Electronic excitation energies, oscillator strength and excited states characteristics were computed by the closed-shell singlet calculation method.

  6. DFT calculations and experimental FT-IR, FT-Raman, NMR, UV-Vis spectral studies of 3-fluorophenylboronic acid.

    PubMed

    Karabacak, M; Kose, E; Sas, E B; Kurt, M; Asiri, A M; Atac, A

    2015-02-01

    The spectroscopic (FT-IR, FT-Raman, (1)H and (13)C NMR, UV-Vis), structural, electronic and thermodynamical properties of 3-fluorophenylboronic acid (C6H4FB(OH)2), 3FPBA) were submitted by using both experimental techniques and theoretical methods (quantum chemical calculations) in this work. The experimental infrared and Raman spectra were obtained in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The equilibrium geometry and vibrational spectra were calculated by using DFT (B3LYP) with 6-311++G(d,p) basis set. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. The total energy distributions (TED) of the vibrational modes were performed for the assignments of the title molecule by using scaled quantum mechanics (SQM) method. The NMR chemical shifts ((1)H and (13)C) were recorded in DMSO solution. The (1)H and (13)C NMR spectra were computed by using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The last one UV-Vis absorption spectra were analyzed in two solvents (ethanol and water), saved in the range of 200-400 nm. In addition these, HOMO and LUMO energies, the excitation energies, density of states (DOS) diagrams, thermodynamical properties and molecular electrostatic potential surface (MEPs) were presented. Nonlinear optical (NLO) properties and thermodynamic features were performed. The experimental results are combined with the theoretical calculations using DFT calculations to fortification of the paper. At the end of this work, the results were proved our paper had been indispensable for the literature backing. PMID:25448934

  7. DFT calculations and experimental FT-IR, FT-Raman, NMR, UV-Vis spectral studies of 3-fluorophenylboronic acid

    NASA Astrophysics Data System (ADS)

    Karabacak, M.; Kose, E.; Sas, E. B.; Kurt, M.; Asiri, A. M.; Atac, A.

    2015-02-01

    The spectroscopic (FT-IR, FT-Raman, 1H and 13C NMR, UV-Vis), structural, electronic and thermodynamical properties of 3-fluorophenylboronic acid (C6H4FB(OH)2), 3FPBA) were submitted by using both experimental techniques and theoretical methods (quantum chemical calculations) in this work. The experimental infrared and Raman spectra were obtained in the region 4000-400 cm-1 and 3500-10 cm-1, respectively. The equilibrium geometry and vibrational spectra were calculated by using DFT (B3LYP) with 6-311++G(d,p) basis set. The vibrational wavenumbers were also corrected with scale factor to take better results for the calculated data. The total energy distributions (TED) of the vibrational modes were performed for the assignments of the title molecule by using scaled quantum mechanics (SQM) method. The NMR chemical shifts (1H and 13C) were recorded in DMSO solution. The 1H and 13C NMR spectra were computed by using the gauge-invariant atomic orbital (GIAO) method, showing a good agreement with the experimental ones. The last one UV-Vis absorption spectra were analyzed in two solvents (ethanol and water), saved in the range of 200-400 nm. In addition these, HOMO and LUMO energies, the excitation energies, density of states (DOS) diagrams, thermodynamical properties and molecular electrostatic potential surface (MEPs) were presented. Nonlinear optical (NLO) properties and thermodynamic features were performed. The experimental results are combined with the theoretical calculations using DFT calculations to fortification of the paper. At the end of this work, the results were proved our paper had been indispensable for the literature backing.

  8. FT-IR spectroscopy and density functional theory calculations of 13C isotopologues of the helical peptide Z-Aib6-OtBu.

    PubMed

    Zeko, Timothy; Hannigan, Steven F; Jacisin, Timothy; Guberman-Pfeffer, Matthew J; Falcone, Eric R; Guildford, Melissa J; Szabo, Christopher; Cole, Kathryn E; Placido, Jessica; Daly, Erin; Kubasik, Matthew A

    2014-01-01

    Isotope-edited FT-IR spectroscopy is a combined synthetic and spectroscopic method used to characterize local (e.g., residue-level) vibrational environments of biomolecules. We have prepared the 3(10) helical peptide Z-Aib6-OtBu and seven (13)C-enriched analogues that vary only in the number and position(s) of (13)C═O isotopic enrichment. FT-IR spectra of these eight peptides solvated in the nonpolar aprotic solvent dichloromethane have been collected and compared to frequency, intensity, and normal mode results of DFT calculations. Single (13)C enrichment of amide functional groups tends to localize amide I vibrational eigenmodes, providing residue-specific information regarding the local environment (e.g., hydrogen bonding or solvent exposure) of the peptide bond. Double (13)C enrichment of Z-Aib6-OtBu allows for examination of interamide coupling between two labeled amide functional groups, providing experimental evidence of interamide coupling in the context of 3(10) helical structure. Although the calculated and observed interamide couplings of Z-Aib6-OtBu are a few cm(-1) and less, the eight peptides exhibit distinct infrared spectra, revealing details of interamide coupling and residue level vibrational environments.

  9. Insilico molecular modeling, docking and spectroscopic [FT-IR/FT-Raman/UV/NMR] analysis of Chlorfenson using computational calculations

    NASA Astrophysics Data System (ADS)

    Ramalingam, S.; Periandy, S.; Sugunakala, S.; Prabhu, T.; Bououdina, M.

    2013-11-01

    In the present work, the recorded FT-IR/FT-Raman spectra of the Chlorfenson (4-Chorophenyl-4-chlorobenzenesulfonate) are analysed. The observed vibrational frequencies are assigned and the computational calculations are carried out by DFT (LSDA, B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results are investigated with the UV/NMR data. The fluctuation of structure of Chlorobenzenesulfonate due to the substitution of C6H4Cl is investigated. The vibrational sequence pattern of the molecule related to the substitutions is intensely analysed. Moreover, 13C NMR and 1H NMR chemical shifts are calculated by using the gage independent atomic orbital (GIAO) technique with HF/B3LYP/B3PW91 methods on same basis set. A study on the electronic properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, are performed by HF and DFT methods. The calculated energy of Kubo gap (HOMO and LUMO) ensures that the charge transfer occurs within the molecule. Besides frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP) is executed. NLO properties and Mulliken charges of the Chlorfenson is also calculated and interpreted. Biological properties like the target receptor identification, and Identification of interacting residues, of this compound is identified and analysed by using SWISSMODEL, Castp, Hex and Pdb Sum. By using these properties, the mechanism of action of this compound on ATP Synthase of Tetranychus urticae is found and it is very much useful to develop efficient pesticides having less toxic to the environment.

  10. Chemical curing in alkyd paints: an evaluation via FT-IR and NMR spectroscopies.

    PubMed

    Bartolozzi, G; Marchiafava, V; Mirabello, V; Peruzzini, M; Picollo, M

    2014-01-24

    A study aimed at determining the time necessary for an alkyd paint to attain chemical curing is presented. In particular, the object of our investigation was an oil paint made by Winsor & Newton, namely French ultramarine (PB29) in the Griffin Alkyd "fast drying oil colour" series. Using this paint, we prepared several mock-ups on glass. These were left in the laboratory at room temperature in a piece of furniture with glass doors for a total of 70 days. Samples were taken at different times, and the changes in their composition were monitored by means of FT-IR and multinuclear NMR spectroscopic analyses. Since the cross-linking reactions involved in the formation of the pictorial film mainly affect the amount of carbon-carbon double bonds, we monitored the decrease in allyl, diallyl and vinyl protons and carbons. The data obtained from the use of both techniques led us to conclude that, in our particular experimental conditions, the chemical curing of the paint layer is reached within the first 70 days, thus establishing the beginning of the ageing phenomena. PMID:24084480

  11. Chemical curing in alkyd paints: An evaluation via FT-IR and NMR spectroscopies

    NASA Astrophysics Data System (ADS)

    Bartolozzi, G.; Marchiafava, V.; Mirabello, V.; Peruzzini, M.; Picollo, M.

    2014-01-01

    A study aimed at determining the time necessary for an alkyd paint to attain chemical curing is presented. In particular, the object of our investigation was an oil paint made by Winsor & Newton, namely French ultramarine (PB29) in the Griffin Alkyd “fast drying oil colour” series. Using this paint, we prepared several mock-ups on glass. These were left in the laboratory at room temperature in a piece of furniture with glass doors for a total of 70 days. Samples were taken at different times, and the changes in their composition were monitored by means of FT-IR and multinuclear NMR spectroscopic analyses. Since the cross-linking reactions involved in the formation of the pictorial film mainly affect the amount of carbon-carbon double bonds, we monitored the decrease in allyl, diallyl and vinyl protons and carbons. The data obtained from the use of both techniques led us to conclude that, in our particular experimental conditions, the chemical curing of the paint layer is reached within the first 70 days, thus establishing the beginning of the ageing phenomena.

  12. FT-IR, dispersive Raman, NMR, DFT and antimicrobial activity studies on 2-(Thiophen-2-yl)-1H-benzo[d]imidazole

    NASA Astrophysics Data System (ADS)

    Ünal, Arslan; Eren, Bilge

    2013-10-01

    2-(Thiophen-2-yl)-1H-benzo[d]imidazole (TBI) was synthesized under microwave conditions and was characterized by FT-IR, dispersive Raman, 1H-, 13C-, DEPT-, HETCOR-NMR spectroscopies and density functional theory (DFT) computations. The FT-IR and dispersive Raman spectra of TBI were recorded in the regions 4000-400 cm-1 and 4000-100 cm-1. The experimental vibrational spectra were interpreted with the help of normal coordinate analysis based on DFT/B3LYP/6-311++G(d,p) theory level for the more stable tautomeric form (Tautomer 1). The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. A satisfactory consistency between the experimental and theoretical findings was obtained. The frontier molecular orbitals (FMOs), atomic charges and NMR shifts of the two stable tautomeric forms were also obtained at the same theory level without any symmetry restrictions. In addition, the title compound was screened for its antimicrobial activity and was found to be exhibit antifungal and antibacterial effects.

  13. FT-IR, dispersive Raman, NMR, DFT and antimicrobial activity studies on 2-(Thiophen-2-yl)-1H-benzo[d]imidazole.

    PubMed

    Unal, Arslan; Eren, Bilge

    2013-10-01

    2-(Thiophen-2-yl)-1H-benzo[d]imidazole (TBI) was synthesized under microwave conditions and was characterized by FT-IR, dispersive Raman, (1)H-, (13)C-, DEPT-, HETCOR-NMR spectroscopies and density functional theory (DFT) computations. The FT-IR and dispersive Raman spectra of TBI were recorded in the regions 4000-400 cm(-1) and 4000-100 cm(-1). The experimental vibrational spectra were interpreted with the help of normal coordinate analysis based on DFT/B3LYP/6-311++G(d,p) theory level for the more stable tautomeric form (Tautomer 1). The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. A satisfactory consistency between the experimental and theoretical findings was obtained. The frontier molecular orbitals (FMOs), atomic charges and NMR shifts of the two stable tautomeric forms were also obtained at the same theory level without any symmetry restrictions. In addition, the title compound was screened for its antimicrobial activity and was found to be exhibit antifungal and antibacterial effects. PMID:23756262

  14. Spectroscopic (FT-IR, FT-Raman, UV and NMR) investigation on 1-phenyl-2-nitropropene by quantum computational calculations

    NASA Astrophysics Data System (ADS)

    Xavier, S.; Periandy, S.

    2015-10-01

    In this paper, the spectral analysis of 1-phenyl-2-nitropropene is carried out using the FTIR, FT Raman, FT NMR and UV-Vis spectra of the compound with the help of quantum mechanical computations using ab-initio and density functional theories. The FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra were recorded in solid phase, the 1H and 13C NMR spectra were recorded in CDCl3 solution phase and the UV-Vis (200-800 nm) spectrum was recorded in ethanol solution phase. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G(d,p) basis set and two stable conformers with lowest energy were identified and the same was used for further computations. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both B3LYP and B3PW91 methods with 6-311+G(d,p) and 6-311++G(d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for 1H and 13C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The local reactivity of the molecule has been studied using the Fukui function. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated.

  15. Molecular structure, spectroscopic characterization (FT-IR, FT-Raman, UV and NMR), HOMO and LUMO analysis of 3-ethynylthiophene with DFT quantum chemical calculations.

    PubMed

    Karabacak, Mehmet; Bilgili, Sibel; Mavis, Tugba; Eskici, Mustafa; Atac, Ahmet

    2013-11-01

    In this work, FT-IR, FT-Raman, UV and NMR spectra of 3-ethynylthiophene (3-ETP, C6H4S) were carried out by using density functional theory DFT/B3LYP method with the 6-311++G(d,p), 6-311+G(d,p), 6-311G(d,p), 6-31++G(d,p), 6-31+G(d,p), 6-31G(d,p) basis sets. FT-IR and FT-Raman spectra were recorded in the regions of 3500-400cm(-1) and 3500-50cm(-1), respectively. The geometrical parameters, energies and wavenumbers were obtained and the complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The (1)H, (13)C and HMQC ((1)H-(13)C correlation) NMR spectra in chloroform (CDCl3) were recorded and calculated. The UV spectrum of investigated compound were recorded in the region of 200-400nm in ethanol solution. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies were performed by DFT/B3LYP approach and the results were compared with experimental observations. The thermodynamic properties such zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment of the studied compound were calculated. As a result, the calculated results were compared with the observed data and found to be in good agreement. PMID:23886506

  16. Molecular structure, spectroscopic characterization (FT-IR, FT-Raman, UV and NMR), HOMO and LUMO analysis of 3-ethynylthiophene with DFT quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Bilgili, Sibel; Mavis, Tugba; Eskici, Mustafa; Atac, Ahmet

    2013-11-01

    In this work, FT-IR, FT-Raman, UV and NMR spectra of 3-ethynylthiophene (3-ETP, C6H4S) were carried out by using density functional theory DFT/B3LYP method with the 6-311++G(d,p), 6-311+G(d,p), 6-311G(d,p), 6-31++G(d,p), 6-31+G(d,p), 6-31G(d,p) basis sets. FT-IR and FT-Raman spectra were recorded in the regions of 3500-400 cm-1 and 3500-50 cm-1, respectively. The geometrical parameters, energies and wavenumbers were obtained and the complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The 1H, 13C and HMQC (1H-13C correlation) NMR spectra in chloroform (CDCl3) were recorded and calculated. The UV spectrum of investigated compound were recorded in the region of 200-400 nm in ethanol solution. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies were performed by DFT/B3LYP approach and the results were compared with experimental observations. The thermodynamic properties such zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment of the studied compound were calculated. As a result, the calculated results were compared with the observed data and found to be in good agreement.

  17. Spectroscopic [FT-IR and FT-Raman] and theoretical [UV-Visible and NMR] analysis on α-Methylstyrene by DFT calculations

    NASA Astrophysics Data System (ADS)

    Karthikeyan, N.; Joseph Prince, J.; Ramalingam, S.; Periandy, S.

    2015-05-01

    In the present research work, the FT-IR, FT-Raman and 13C and 1H NMR spectra of the α-Methylstyrene were recorded. The observed fundamental frequencies in finger print as well as functional group regions were assigned according to their uniqueness region. The Gaussian computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The impact of the presence of vinyl group in phenyl structure of the compound is investigated. The modified vibrational pattern of the molecule associated vinyl group was analyzed. Moreover, 13C NMR and 1H NMR were calculated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts linked to TMS were compared. A study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies were carried out. The kubo gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The NLO properties related to Polarizability and hyperpolarizability based on the finite-field approach were also discussed.

  18. NMR, FT-IR, Raman and UV-Vis spectroscopic investigation and DFT study of 6-Bromo-3-Pyridinyl Boronic Acid

    NASA Astrophysics Data System (ADS)

    Dikmen, Gökhan; Alver, Özgür

    2015-11-01

    Possible stable conformers and geometrical molecular structures of 6-Bromo-3-Pyridinyl Boronic acid (6B3PBA; C5H5BBrNO2) were studied experimentally and theoretically using FT-IR and Raman spectroscopic methods. FT-IR and Raman spectra were recorded in the region of 4000-400 cm-1 and 3700-400 cm-1, respectively. The structural properties were investigated further, using 1H, 13C, 1H coupled 13C, HETCOR, COSY and APT NMR techniques. The optimized geometric structures were searched by Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. Vibrational wavenumbers of 6B3PBA were calculated whereby B3LYP density functional methods including 6-311++G(d, p), 6-311G(d, p), 6-311G(d), 6-31G(d, p) and 6-31G(d) basis sets. The comparison of the experimentally and theoretically obtained results using mean absolute error and experimental versus calculated correlation coefficients for the vibrational wavenumbers indicates that B3LYP method with 6-311++G(d, p) gives more satisfactory results for predicting vibrational wavenumbers when compared to the 6-311G(d, p), 6-311G(d), 6-31G(d, p) and 6-31G(d) basis sets. However, this method and none of the mentioned methods here seem suitable for the calculations of OH stretching modes, most likely because increasing unharmonicity in the high wave number region and possible intra and inter molecular interactions at OH edges lead some deviations between experimental and theoretical results. Moreover, reliable vibrational assignments were made on the basis of total energy distribution (TED) calculated using scaled quantum mechanical (SQM) method.

  19. FT-IR and FT-Raman, NMR and UV spectroscopic investigation and hybrid computational (HF and DFT) analysis on the molecular structure of mesitylene

    NASA Astrophysics Data System (ADS)

    Kose, E.; Atac, A.; Karabacak, M.; Nagabalasubramanian, P. B.; Asiri, A. M.; Periandy, S.

    2013-12-01

    The spectroscopic properties of mesitylene were investigated by FT-IR, FT-Raman, UV, 1H and 13C NMR techniques. The geometrical parameters and energies have been obtained from density functional theory (DFT) B3LYP method and Hartree-Fock (HF) method with 6-311++G(d,p) and 6-311G(d,p) basis sets calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. 13C and 1H NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed. Reduced density gradient (RDG) of the mesitylene was also given to investigate interactions of the molecule.

  20. FT-IR and FT-Raman, NMR and UV spectroscopic investigation and hybrid computational (HF and DFT) analysis on the molecular structure of mesitylene.

    PubMed

    Kose, E; Atac, A; Karabacak, M; Nagabalasubramanian, P B; Asiri, A M; Periandy, S

    2013-12-01

    The spectroscopic properties of mesitylene were investigated by FT-IR, FT-Raman, UV, (1)H and (13)C NMR techniques. The geometrical parameters and energies have been obtained from density functional theory (DFT) B3LYP method and Hartree-Fock (HF) method with 6-311++G(d,p) and 6-311G(d,p) basis sets calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. (13)C and (1)H NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed. Reduced density gradient (RDG) of the mesitylene was also given to investigate interactions of the molecule. PMID:23978748

  1. Spectroscopic (FT-IR, FT-Raman, UV and NMR) investigation and NLO, HOMO-LUMO, NBO analysis of organic 2,4,5-trichloroaniline

    NASA Astrophysics Data System (ADS)

    Govindarajan, M.; Karabacak, M.; Periandy, S.; Tanuja, D.

    2012-11-01

    In this work, the experimental and theoretical study on the molecular structure and vibrational spectra of 2,4,5-trichloroaniline (C6H4NCl3, abbreviated as 2,4,5-TClA) were studied. The FT-IR and FT-Raman spectra were recorded. The molecular geometry and vibrational frequencies in the ground state were calculated by using the Hartree-Fock (HF) and density functional theory (DFT) methods (B3LYP) with 6-311++G(d,p) basis set. Comparison of the observed fundamental vibrational frequencies of 2,4,5-TClA with calculated results by HF and DFT indicates that B3LYP is superior to HF method for molecular vibrational problems. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. A study on the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (μ) and the first hyperpolarizability (β) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the 2,4,5-TClA molecule may have microscopic nonlinear optical (NLO) behavior with non-zero values. Mulliken atomic charges of 2,4,5-TClA was calculated and compared with aniline and chlorobenzene molecules. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  2. Spectroscopic (FT-IR, FT-Raman, UV, NMR, NBO) investigation and molecular docking study of (R)-2-Amino-1-PhenylEthanol

    NASA Astrophysics Data System (ADS)

    Subashini, K.; Periandy, S.

    2016-08-01

    A systematic spectroscopic study of (R)-2-Amino-1-Phenylethanol was carried out using FT-IR, FT-Raman, NMR and UV analysis. FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectrum of the title molecule were recorded in solid phase, the 1H and 13C NMR spectra were recorded in CDCl3 (deuterated chloroform) solution phase and the UV-Vis (200-800 nm) spectrum was recorded in gas phase and ethanol solution phase. Potential energy surface (PES) scan was performed using B3LYP functional with 6-311++G (d, p) basis set. The geometrical parameters (such as bond length, bond angle, dihedral angles) and theoretical frequencies of the title compound were studied from density functional theory (DFT) using B3LYP and B3PW91 functionals with 6-311++G (d, p) basis sets. The computed frequencies were scaled and compared with the experimental values and potential energy distribution (PED) has been tabulated. A comparative study of atomic charges was made by calculating Mulliken, Natural Population Analysis (NPA) and Electrostatic Potential (ESP) simultaneously, with B3LYP/6-311++G (d, p) basis set. 1H and 13C NMR spectra were recorded and chemical shifts were compared to TMS by Gauge-Independent Atomic Orbital (GIAO) method. Electronic properties such as excitation energy, energy gap between HOMO and LUMO was calculated using time dependent DFT technique. NBO analysis, which predicts the different possibilities of electronic transition in the molecule, was computed using B3PW91 functional with 6-311++G (d, p) basis set. The thermodynamic properties such as heat capacity, entropy and enthalpy at different temperatures were computed and analyzed. Molecular docking study shows that the secondary hydroxyl group and the primary amino group in the aliphatic chain attached to the benzene ring are crucial for binding and the title compound might exhibit inhibitory activity against Bacteroides fragilis (3P24) and may act as anti-bacterial agent.

  3. On the Traceability of Commercial Saffron Samples Using ¹H-NMR and FT-IR Metabolomics.

    PubMed

    Consonni, Roberto; Ordoudi, Stella A; Cagliani, Laura R; Tsiangali, Maria; Tsimidou, Maria Z

    2016-02-29

    In previous works on authentic samples of saffron of known history (harvest and processing year, storage conditions, and length of time) some biomarkers were proposed using both FT-IR and NMR metabolomics regarding the shelf life of the product. This work addresses the difficulties to trace back the "age" of commercial saffron samples of unknown history, sets a limit value above which these products can be considered substandard, and offers a useful tool to combat saffron mislabeling and fraud with low-quality saffron material. Investigations of authentic and commercial saffron samples of different origin and harvest year, which had been stored under controlled conditions for different lengths of time, allowed a clear-cut clustering of samples in two groups according to the storage period irrespectively of the provenience. In this respect, the four-year cut off point proposed in our previous work assisted to trace back the "age" of unknown samples and to check for possible mislabeling practices.

  4. Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 2-acetoxybenzoic acid by density functional methods

    NASA Astrophysics Data System (ADS)

    Bhavani, K.; Renuga, S.; Muthu, S.; Sankara narayanan, K.

    2015-02-01

    In this work, colorless crystals of 2-acetoxybenzoic acid were grown by slow evaporation method and the FT-IR and FT-Raman spectra of the sample were recorded in the region 4000-500 cm-1 and 4000-100 cm-1 respectively. Molecular structure is optimized with the help of density functional theory method (B3LYP) with 6-31+G(d,p), 6-311++G(d,p) basis sets. Stability of the molecule arising from hyperconjugation and charge delocalization is confirmed by the natural bond orbital analysis (NBO). The results show that electron density (ED) in the σ∗ antibonding orbitals and E(2) energies confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis following the scaled quantum mechanical force field (SQMFF) methodology. The results of the calculations were applied to simulated spectra of the title compound, which show excellent agreement with observed spectra. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. Mulliken population analysis on atomic charges is also calculated. The calculated HOMO and LUMO energy gap shows that charge transfer occurs within the molecule.

  5. Molecular structure, vibrational analysis (FT-IR, FT-Raman), NMR, UV, NBO and HOMO-LUMO analysis of N,N-Diphenyl Formamide based on DFT calculations

    NASA Astrophysics Data System (ADS)

    Mathammal, R.; Monisha, N. R.; Yasaswini, S.; Krishnakumar, V.

    2015-03-01

    In this work, the vibrational spectral analysis is carried out by using Raman and infrared spectroscopy in the range 4000-400 cm-1 and 4000-50 cm-1 respectively for N,N-Diphenyl Formamide (DPF) molecule. The optimized molecular structures, vibrational frequencies and corresponding vibrational assignments, nuclear magnetic resonance (NMR) and ultraviolet-visible (UV-VIS) spectra of the title molecule are evaluated using density functional theory (DFT) with standard B3LYP/6-31G(d, p) basis set. The harmonic vibrational frequencies are calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The stability of the molecule arising from hyper conjugative interactions and the charge delocalization has been analyzed using natural bond (NBO) analysis. The possible electronic transitions are determined by HOMO-LUMO orbital shapes and their energies. Thermodynamic properties (heat capacity, entropy and enthalpy) and the first hyperpolarizability of the title compound are calculated. The Mulliken charges and electric dipole moment of the molecule are computed using DFT calculations. The 1H and 13C nuclear magnetic resonance (NMR) chemical shift of the molecules are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  6. Molecular vibrational investigation [FT-IR, FT-Raman, UV-Visible and NMR] on Bis(thiourea) Nickel chloride using HF and DFT calculations

    NASA Astrophysics Data System (ADS)

    Anand, S.; Sundararajan, R. S.; Ramachandraraja, C.; Ramalingam, S.; Durga, R.

    2015-03-01

    In the present research work, the FT-IR, FT-Raman spectra of the Bis(thiourea) Nickel chloride (BTNC) were recorded and analyzed. The observed fundamental frequencies in finger print and functional group regions were assigned according to their uniqueness region. The computational calculations were carried out by HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The present organo-metallic compound was made up of covalent and coordination covalent bonds. The modified vibrational pattern of the complex molecule associated with ligand group was analyzed. Furthermore, the 13C NMR and 1H NMR spectral data were calculated by using the gauge independent atomic orbital (GIAO) method with B3LYP/6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts linked to TMS were compared. A investigation on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies were carried out. The kubo gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The NLO properties related to Polarizability and hyperpolarizability based on the finite-field approach were also discussed.

  7. Combined experimental and quantum chemical studies on spectroscopic (FT-IR, FT-Raman, UV-Vis, and NMR) and structural characteristics of quinoline-5-carboxaldehyde

    NASA Astrophysics Data System (ADS)

    Kumru, Mustafa; Altun, Ahmet; Kocademir, Mustafa; Küçük, Vesile; Bardakçı, Tayyibe; Şaşmaz, İbrahim

    2016-12-01

    Comparative experimental and theoretical studies have been performed on the structure and spectral (FT-IR, FT-Raman, UV-Vis and NMR) features of quinoline-5-carboxaldehyde. Quantum chemical calculations have been carried out at Hartree-Fock and density functional B3LYP levels with the triple-zeta 6-311++G** basis set. Two stable conformers of quinoline-5-carboxaldehyde arising from the orientation of the carboxaldehyde moiety have been located at the room temperature. The energetic separation of these conformers is as small as 2.5 kcal/mol with a low transition barrier (around 9 kcal/mol). Therefore, these conformers are expected to coexist at the room temperature. Several molecular characteristics of quinoline-5-carboxaldehyde obtained through B3LYP and time-dependent B3LYP calculations, such as conformational stability, key geometry parameters, vibrational frequencies, IR and Raman intensities, UV-Vis vertical excitation energies and the corresponding oscillator strengths have been analyzed. The 1H and 13C NMR chemical shifts of quinoline-5-carboxaldehyde were also investigated.

  8. Molecular structure, FT-IR, FT-Raman, NMR studies and first order molecular hyperpolarizabilities by the DFT method of mirtazapine and its comparison with mianserin

    NASA Astrophysics Data System (ADS)

    Sagdinc, Seda G.; Sahinturk, Ayse Erbay

    2013-03-01

    Mirtazapine (±)-1,2,3,4,10,14b-hexahydro-2-methylpyrazino(2,1-a)pyrido(2,3-c)(2)benzazepine is a compound with antidepressant therapeutic effects. It is the 6-aza derivative of the tetracyclic antidepressant mianserin (±)-2-methyl-1,2,3,4,10,14b-hexahydrodibenzo[c,f]pyrazino[1,2-a]azepine. The FT-IR and FT-Raman spectra of mirtazapine have been recorded in 4000-400 cm-1 and 3500-10 cm-1, respectively. The optimized geometry, energies, nonlinear optical properties, vibrational frequencies, 13C, 1H and 15N NMR chemical shift values of mirtazapine have been determined using the density functional theory (DFT/B3LYP) method. A comparison of the experimental and theoretical results of mirtazapine indicates that the density-functional B3LYP method is able to provide satisfactory results for predicting vibrational and NMR properties. The experimental and calculated results for mirtazapine have also been compared with mianserin.

  9. NBO, HOMO-LUMO, UV, NLO, NMR and vibrational analysis of veratrole using FT-IR, FT-Raman, FT-NMR spectra and HF-DFT computational methods.

    PubMed

    Suvitha, A; Periandy, S; Gayathri, P

    2015-03-01

    This work deals with FT-IR, FT-Raman and FT-NMR spectral analysis and NBO, NLO, HOMO-LUMO and electronic transitions studies on veratrole. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands were interpreted with the aid of structure optimizations and geometrical parameter calculations based on Hartree-Fock (HF) and density functional theory (DFT) method with 6-311++G(d, p) basis set. A study on the electronic properties, such as HOMO and LUMO energies were performed by time independent DFT approach. In addition, molecular electrostatic potential (MEP), Natural Bond-Orbital (NBO) analysis and thermodynamic properties were performed. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by gauge independent atomic orbital (GIAO) method and compared with experimental chemical shift.

  10. The spectroscopic (FT-IR, FT-Raman, dispersive Raman and NMR) study of ethyl-6-chloronicotinate molecule by combined density functional theory.

    PubMed

    Karabacak, Mehmet; Calisir, Zuhre; Kurt, Mustafa; Kose, Etem; Atac, Ahmet

    2016-01-15

    In this study, ethyl-6-chloronicotinate (E-6-ClN) molecule is recorded in the region 4000-400 cm(-1) and 3500-100 cm(-1) (FT-IR, FT-Raman and dispersive Raman, respectively) in the solid phase. ((1))H and ((13))C nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The structural and spectroscopic data of the molecule are obtained for two possible isomers (S1 and S2) from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule is fully optimized, vibrational spectra are calculated and fundamental vibrations are assigned on the basis of the potential energy distribution (PED) of the vibrational modes. ((1))H and ((13))C NMR chemical shifts are calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strengths, wavelengths, HOMO and LUMO energies, are performed by time-dependent density functional theory (TD-DFT). Total and partial density of state and overlap population density of state diagrams analysis are presented for E-6-ClN molecule. Furthermore, frontier molecular orbitals (FMO), molecular electrostatic potential, and thermodynamic features are performed. In addition to these, reduced density gradient of the molecule is performed and discussed. As a conclusion, the calculated results are compared with the experimental spectra of the title compound. The results of the calculations are applied to simulate the vibrational spectra of the molecule, which show excellent agreement with the observed ones. The theoretical and tentative results will give us a detailed description of the structural and physicochemical properties of the molecule. Natural bond orbital analysis is done to have more information stability of the molecule arising from charge delocalization, and to reveal the information regarding charge transfer within the molecules. PMID:26483317

  11. Spectroscopic (FT-IR, FT-Raman, UV, NMR, NBO, NLO) investigation and molecular docking study of (R)-2-Methylamino-1-Phenylethanol (Halostachine)

    NASA Astrophysics Data System (ADS)

    Subashini, K.; Govindarajan, R.; Surendran, R.; Mukund, K.; Periandy, S.

    2016-12-01

    FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectra of (R)-2-Methylamino-1-Phenylethanol have been recorded in solid phase, 1H and 13C NMR in deuterated chloroform (CDCl3) phase and UV spectrum (200-400 nm) in solid phase and in ethanol solution. The different conformers of the compound and their minimum energies were studied by potential energy surface scan, using semi-empirical method PM6. The computed wavenumbers obtained from B3LYP and B3PW91 functionals along with 6-311++G (d, p) basis sets were scaled so as to agree with the experimental values and the scaling factors have been reported. All the fundamental modes have been assigned based on the potential energy distribution (PED) values and the structure of the molecule was analyzed in parameters like bond length, bond angle and dihedral angles through B3LYP and B3PW91 functionals along with 6-311++G(d,p) basis set. The values of dipole moment (μ), polarizability (α) and hyper polarizability (β) of the molecule were calculated using which, the non-linear optical property of the molecule has been discussed. The observed HOMO-LUMO mappings reveals the different charge transfer possibilities within the molecule. Natural Bond Orbital analysis was computed and possible transitions were correlated with the electronic transitions. Mulliken charges, electrostatic potential charges and natural charges are also predicted. The theoretical 1H and 13C NMR chemical shifts were computed using B3LYP functionals using 6-311++G (2d, p) basis sets. The temperature dependence of the thermodynamic properties; heat capacity, entropy and enthalpy for the title compound were also determined by B3LYP functionals with 6-311++G (d, p) basis set. Molecular docking study shows that the title compound might exhibit inhibitory activity against Bacillus anthracis (3V5O).

  12. FT-IR, FT-Raman, NMR and UV-Vis spectra and DFT calculations of 5-bromo-2-ethoxyphenylboronic acid (monomer and dimer structures).

    PubMed

    Sas, E B; Kose, E; Kurt, M; Karabacak, M

    2015-02-25

    In this study, the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of 5-bromo-2-ethoxyphenylboronic acid (5Br2EPBA) are recorded in the solid phase in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The (1)H, (13)C and DEPT nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The UV-Vis absorption spectrum of 5Br2EPBA is saved in the range of 200-400 nm in ethanol and water. The following theoretical calculations for monomeric and dimeric structures are supported by experimental results. The molecular geometry and vibrational frequencies in the ground state are calculated by using DFT methods with 6-31G(d,p) and 6-311G(d,p) basis sets. There are four conformers for the present molecule. The computational results diagnose the most stable conformer of 5Br2EPBA as Trans-Cis (TC) form. The complete assignments are performed on the basis of the total energy distribution (TED) of vibrational modes, calculated with scaled quantum mechanics (SQM) method in parallel quantum solutions (PQS) program. The (1)H and (13)C NMR chemical shifts of 5Br2EPBA molecule are calculated by using the Gauge Invariant Atomic Orbital (GIAO) method in DMSO and gas phase for monomer and dimer structures of the most stable conformer. Moreover, electronic properties, such as the HOMO and LUMO energies (by TD-DFT and CIS methods) and molecular electrostatic potential surface (MEPs) are investigated. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization is analyzed using natural bond orbital (NBO) analysis. Nonlinear optical (NLO) properties and thermodynamic features are presented. All calculated results are compared with the experimental data of the title molecule. The correlation of theoretical and experimental results provides a detailed description of the structural and physicochemical properties of the title molecule.

  13. The spectroscopic (FT-IR, FT-Raman, dispersive Raman and NMR) study of ethyl-6-chloronicotinate molecule by combined density functional theory

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Calisir, Zuhre; Kurt, Mustafa; Kose, Etem; Atac, Ahmet

    2016-01-01

    In this study, ethyl-6-chloronicotinate (E-6-ClN) molecule is recorded in the region 4000-400 cm- 1 and 3500-100 cm- 1 (FT-IR, FT-Raman and dispersive Raman, respectively) in the solid phase. 1H and 13C nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The structural and spectroscopic data of the molecule are obtained for two possible isomers (S1 and S2) from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule is fully optimized, vibrational spectra are calculated and fundamental vibrations are assigned on the basis of the potential energy distribution (PED) of the vibrational modes. 1H and 13C NMR chemical shifts are calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strengths, wavelengths, HOMO and LUMO energies, are performed by time-dependent density functional theory (TD-DFT). Total and partial density of state and overlap population density of state diagrams analysis are presented for E-6-ClN molecule. Furthermore, frontier molecular orbitals (FMO), molecular electrostatic potential, and thermodynamic features are performed. In addition to these, reduced density gradient of the molecule is performed and discussed. As a conclusion, the calculated results are compared with the experimental spectra of the title compound. The results of the calculations are applied to simulate the vibrational spectra of the molecule, which show excellent agreement with the observed ones. The theoretical and tentative results will give us a detailed description of the structural and physicochemical properties of the molecule. Natural bond orbital analysis is done to have more information stability of the molecule arising from charge delocalization, and to reveal the information regarding charge transfer within the molecules.

  14. Spectroscopic (FT-IR, FT-Raman, FT-NMR and UV-Vis) investigation on benzil dioxime using quantum computational methods

    NASA Astrophysics Data System (ADS)

    Bakkiyaraj, D.; Periandy, S.; Xavier, S.

    2016-03-01

    The spectral analysis of benzil dioxime is carried out using the FTIR, FT Raman, FT NMR and UV-Vis spectra of the compound with the help of quantum computations by density functional theories. The FT-IR (4000 - 400 cm-1) and FT-Raman (4000-100 cm-1) spectra are recorded in solid phase, the 1H and 13C NMR spectra in DMSO phase and the UV spectrum (200-400 nm) in ethanol phase. The different conformers of the compound and their minimum energies are studied by potential energy surface scan, using semi-empirical method PM6. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the fundamental modes have been assigned based on the potential energy distribution (PED) values and the structure the molecule is analyzed interms of parameters like bond length, bond angle and dihedral angles predicted byB3LYP and CAM-B3LYP methods with cc-pVDZ basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non -linear optical property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for 1H and 13C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts and the same is discussed in comparison with atomic charges, predicted by Mullikan and APT charge analysis. NBO analysis is carried out to picture the probable electronic transitions in the molecule.

  15. FT-IR, FT-Raman, NMR and UV-Vis spectra and DFT calculations of 5-bromo-2-ethoxyphenylboronic acid (monomer and dimer structures).

    PubMed

    Sas, E B; Kose, E; Kurt, M; Karabacak, M

    2015-02-25

    In this study, the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of 5-bromo-2-ethoxyphenylboronic acid (5Br2EPBA) are recorded in the solid phase in the region 4000-400 cm(-1) and 3500-10 cm(-1), respectively. The (1)H, (13)C and DEPT nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The UV-Vis absorption spectrum of 5Br2EPBA is saved in the range of 200-400 nm in ethanol and water. The following theoretical calculations for monomeric and dimeric structures are supported by experimental results. The molecular geometry and vibrational frequencies in the ground state are calculated by using DFT methods with 6-31G(d,p) and 6-311G(d,p) basis sets. There are four conformers for the present molecule. The computational results diagnose the most stable conformer of 5Br2EPBA as Trans-Cis (TC) form. The complete assignments are performed on the basis of the total energy distribution (TED) of vibrational modes, calculated with scaled quantum mechanics (SQM) method in parallel quantum solutions (PQS) program. The (1)H and (13)C NMR chemical shifts of 5Br2EPBA molecule are calculated by using the Gauge Invariant Atomic Orbital (GIAO) method in DMSO and gas phase for monomer and dimer structures of the most stable conformer. Moreover, electronic properties, such as the HOMO and LUMO energies (by TD-DFT and CIS methods) and molecular electrostatic potential surface (MEPs) are investigated. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization is analyzed using natural bond orbital (NBO) analysis. Nonlinear optical (NLO) properties and thermodynamic features are presented. All calculated results are compared with the experimental data of the title molecule. The correlation of theoretical and experimental results provides a detailed description of the structural and physicochemical properties of the title molecule. PMID:25305625

  16. FT-IR, FT-Raman, NMR and UV-Vis spectra and DFT calculations of 5-bromo-2-ethoxyphenylboronic acid (monomer and dimer structures)

    NASA Astrophysics Data System (ADS)

    Sas, E. B.; Kose, E.; Kurt, M.; Karabacak, M.

    2015-02-01

    In this study, the Fourier Transform Infrared (FT-IR) and Fourier Transform Raman (FT-Raman) spectra of 5-bromo-2-ethoxyphenylboronic acid (5Br2EPBA) are recorded in the solid phase in the region 4000-400 cm-1 and 3500-10 cm-1, respectively. The 1H, 13C and DEPT nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The UV-Vis absorption spectrum of 5Br2EPBA is saved in the range of 200-400 nm in ethanol and water. The following theoretical calculations for monomeric and dimeric structures are supported by experimental results. The molecular geometry and vibrational frequencies in the ground state are calculated by using DFT methods with 6-31G(d,p) and 6-311G(d,p) basis sets. There are four conformers for the present molecule. The computational results diagnose the most stable conformer of 5Br2EPBA as Trans-Cis (TC) form. The complete assignments are performed on the basis of the total energy distribution (TED) of vibrational modes, calculated with scaled quantum mechanics (SQM) method in parallel quantum solutions (PQS) program. The 1H and 13C NMR chemical shifts of 5Br2EPBA molecule are calculated by using the Gauge Invariant Atomic Orbital (GIAO) method in DMSO and gas phase for monomer and dimer structures of the most stable conformer. Moreover, electronic properties, such as the HOMO and LUMO energies (by TD-DFT and CIS methods) and molecular electrostatic potential surface (MEPs) are investigated. Stability of the molecule arising from hyper-conjugative interactions, charge delocalization is analyzed using natural bond orbital (NBO) analysis. Nonlinear optical (NLO) properties and thermodynamic features are presented. All calculated results are compared with the experimental data of the title molecule. The correlation of theoretical and experimental results provides a detailed description of the structural and physicochemical properties of the title molecule.

  17. Vibrational [FT-IR, FT-Raman] analysis, NMR and mass - Spectroscopic investigation on 3,6-Dimethylphenanthrene using computational calculation

    NASA Astrophysics Data System (ADS)

    Manzoor Ali, M.; George, Gene; Ramalingam, S.; Periandy, S.; Gokulakrishnan, V.

    2015-11-01

    In this research work, in order to the vibrational, physical and chemical properties, a thorough investigation has been made by recording FT-IR, FT-Raman, Mass and 13C and 1H NMR spectra of pharmaceutically important compound; 3,6-Dimethylphenanthrene. The altered geometrical parameters of Phenanthrene due to the addition of methyl groups have been calculated using HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the discussion are made on their corresponding results. The alternation of the vibrational pattern of the molecule due to the injection of the substitutions; CH3 is investigated. The keen observation is made over the excitations between the electronic energy levels of the molecule which lead to the study of electronic properties. The alternation of distribution of Mulliken charges after the formation of present molecule has been correlated with the vibrational pattern of the molecular bonds. The charge transformation over the frontier molecular orbitals between the ligand and rings has been studied. The cause of the linear and non linear optical activity of the molecule is interpreted in detail from the average Polarizability first order diagonal hyperpolarizability calculations. The variation of thermodynamic properties; heat capacity, entropy, and enthalpy of the present compound at different temperatures are calculated using NIST thermodynamical function program and interpreted.

  18. The spectroscopic properties of anticancer drug Apigenin investigated by using DFT calculations, FT-IR, FT-Raman and NMR analysis

    NASA Astrophysics Data System (ADS)

    Mariappan, G.; Sundaraganesan, N.; Manoharan, S.

    2012-09-01

    The FT-Raman and FT-Infrared spectra of solid Apigenin sample were measured in order to elucidate the spectroscopic properties of title molecule in the spectral range of 3500-50 cm-1 and 4000-400 cm-1, respectively. The recorded FT-IR and FT-Raman spectral measurements favor the calculated (by B3LYP/6-31G(d,p) method) structural parameters which are further supported by spectral simulation. Additional support is given by the collected 1H and 13C NMR spectra recorded with the sample dissolved in DMSO. The predicted chemical shifts at the B3LYP/6-31G(d) level obtained using the Gauge-Invariant Atomic Orbitals (GIAO) method with and without inclusion of solvent using the Polarizable Continuum Model (PCM). By using TD-DFT method, electronic absorption spectra of the title compound have been predicted and a good agreement with the TD-DFT method and the experimental one is determined. The UV-visible absorption spectra of the compound that dissolved in Ethanol, Methanol and DMSO were recorded in the range of 800-200 nm. The formation of hydrogen bond and the most possible interaction are explained using natural bond orbital (NBO) analysis. In addition, the molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis and atomic charges of the title compound were investigated using theoretical calculations. The results are discussed herein and compared with similar molecules whenever appropriate.

  19. Quantum mechanical, spectroscopic studies (FT-IR, FT-Raman, NMR, UV) and normal coordinates analysis on 3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide.

    PubMed

    Muthu, S; Uma Maheswari, J; Sundius, Tom

    2013-05-01

    Famotidine (3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide) is a histamine H2-receptor antagonist that inhibits stomach acid production, and it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). Quantum chemical calculations of the equilibrium geometry of famotidine in the ground state were carried out using density functional theory (DFT/B3LYP) with the 6-311G(d,p) basis set. In addition, harmonic vibrational frequencies, infrared intensities and Raman activities were calculated at the same level of theory. A detailed interpretation of the infrared and Raman spectrum of the drug is also reported. Theoretical simulations of the FT-IR, and FT-Raman spectra of the title compound have been calculated. Good correlations between the experimental (1)H and (13)C NMR chemical shifts and calculated GIAO shielding tensors were found. The results of the energy and oscillator strength calculations by time-dependent density functional theory (TD-DFT) supplement the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The linear polarizability and first order hyperpolarizabilities of the studied molecule indicate that the compound is a good candidate for nonlinear optical materials. PMID:23507526

  20. Quantum mechanical, spectroscopic studies (FT-IR, FT-Raman, NMR, UV) and normal coordinates analysis on 3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide

    NASA Astrophysics Data System (ADS)

    Muthu, S.; Uma Maheswari, J.; Sundius, Tom

    2013-05-01

    Famotidine (3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide) is a histamine H2-receptor antagonist that inhibits stomach acid production, and it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). Quantum chemical calculations of the equilibrium geometry of famotidine in the ground state were carried out using density functional theory (DFT/B3LYP) with the 6-311G(d,p) basis set. In addition, harmonic vibrational frequencies, infrared intensities and Raman activities were calculated at the same level of theory. A detailed interpretation of the infrared and Raman spectrum of the drug is also reported. Theoretical simulations of the FT-IR, and FT-Raman spectra of the title compound have been calculated. Good correlations between the experimental 1H and 13C NMR chemical shifts and calculated GIAO shielding tensors were found. The results of the energy and oscillator strength calculations by time-dependent density functional theory (TD-DFT) supplement the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The linear polarizability and first order hyperpolarizabilities of the studied molecule indicate that the compound is a good candidate for nonlinear optical materials.

  1. FT-IR, FT-Raman, UV-Visible, and NMR spectroscopy and vibrational properties of the labdane-type diterpene 13-epi-sclareol

    NASA Astrophysics Data System (ADS)

    Chain, Fernando E.; Leyton, Patricio; Paipa, Carolina; Fortuna, Mario; Brandán, Silvia A.

    2015-03-01

    In this work, FT-IR, FT-Raman, UV-Visible and NMR spectroscopies and density functional theory (DFT) calculations were employed to study the structural and vibrational properties of the labdane-type diterpene 13-epi-sclareol using the hybrid B3LYP method together with the 6-31G∗ basis set. Three stable structures with minimum energy found on the potential energy curves (PES) were optimized, and the corresponding molecular electrostatic potentials, atomic charges, bond orders, stabilization energies and topological properties were computed at the same approximation level. The complete assignment of the bands observed in the vibrational spectrum of 13-epi-sclareol was performed taking into account the internal symmetry coordinates for the three structures using the scaled quantum mechanical force field (SQMFF) methodology at the same level of theory. In addition, the force constants were calculated and compared with those reported in the literature for similar compounds. The predicted vibrational spectrum and the calculated 1H NMR and 13C NMR chemical shifts are in good agreement with the corresponding experimental results. The theoretical UV-Vis spectra for the most stable structure of 13-epi-sclareol demonstrate a better correlation with the corresponding experimental spectrum. The study of the three conformers by means of the theory of atoms in molecules (AIM) revealed different H bond interactions and a strong dependence of the interactions on the distance between the involved atoms. Furthermore, the natural bond orbital (NBO) calculations showed the characteristics of the electronic delocalization for the two six-membered rings with chair conformations.

  2. On the Traceability of Commercial Saffron Samples Using ¹H-NMR and FT-IR Metabolomics.

    PubMed

    Consonni, Roberto; Ordoudi, Stella A; Cagliani, Laura R; Tsiangali, Maria; Tsimidou, Maria Z

    2016-01-01

    In previous works on authentic samples of saffron of known history (harvest and processing year, storage conditions, and length of time) some biomarkers were proposed using both FT-IR and NMR metabolomics regarding the shelf life of the product. This work addresses the difficulties to trace back the "age" of commercial saffron samples of unknown history, sets a limit value above which these products can be considered substandard, and offers a useful tool to combat saffron mislabeling and fraud with low-quality saffron material. Investigations of authentic and commercial saffron samples of different origin and harvest year, which had been stored under controlled conditions for different lengths of time, allowed a clear-cut clustering of samples in two groups according to the storage period irrespectively of the provenience. In this respect, the four-year cut off point proposed in our previous work assisted to trace back the "age" of unknown samples and to check for possible mislabeling practices. PMID:26938515

  3. (1)H NMR and FT-IR dataset based structural investigation of poly(amic acid)s and polyimides from 4,4'-diaminostilbene.

    PubMed

    Kumar, Amit; Tateyama, Seiji; Yasaki, Katsuaki; Ali, Mohammad Asif; Takaya, Naoki; Singh, Rajeev; Kaneko, Tatsuo

    2016-06-01

    Structural investigation of polymers by various available analytical methods is important in order to correlate the structure with polymer properties for which understanding of polymer structure is very important factor. The data presented here in this article shows the (1)H NMR spectra used for the characterization of prepared poly(amic acid)s (PAAs). It is often difficult to assigns the peak in NMR of polymers due to its complexity. Data presented here helps in assigning the proton peak in complex NMR of PAAs prepared from aromatic diamines. Further functionality in polymer chains can be confirmed by FT-IR spectra. Change in functionality during some reaction or process can be monitored by disappearance or appearance of peaks in FT-IR. The complete imidization of PAAs to Polyimides (PIs) is difficult to analyze because of the chemical stability i.e. insolubility of PIs in most of the solvent therefore the completion of imidization process was confirmed using FTIR.

  4. Molecular Details of Acetate Binding to a New Diamine Receptor by NMR and FT-IR Analyses.

    PubMed

    Banerji, Biswadip; Chatterjee, Moumita; Pal, Uttam; Maiti, Nakul Chandra

    2016-04-21

    Acetate anion plays an important role in several biochemical functions such as enzyme reaction, antibody response, and action of receptor molecules. This investigation reports the synthesis and molecular details of a unique receptor, 2-amino-N-(2-amino-benzyl)-benzamide (R) that senses selectively acetate via simultaneous involvement of one aromatic amine group and an amide proton of the receptor molecule. Solution-state NMR, steady-state fluorescence, and FT-IR examinations established that the acetate anion binds to the receptor with 1:1 ratio with high specificity. The binding was stabilized by two H-bond formations between the oxygen atoms of acetate anion and two H atoms, one from amide group and the other from the amine group of the receptor. The binding interaction caused significant changes in the chemical shift of the receptor protons, and the evaluated affinity constant, from the NMR measurements, was found to be 1.87 × 10(4) M(-1). Density functional theory (DFT) analysis further showed a significant rotation of one of the two aromatic rings leading to formation of a 10-member ring involving the acetate anion, amide proton, and the one amine group attached to aromatic ring. The H-bond patterns observed in the crystal structure were significantly changed due to complex formation. However, the changes in the geometrical arrangement in the complex caused a small but significant increase of the fluorescence emission. Acetate geometry and unique positioning of the amide and amine groups of the receptor render the recognition feasible, and DFT analysis estimated ∼30 kJ M(-1) stabilization due to 1:1 complexation. Such positioning and geometrical arrangement may make the receptor very specific to bind acetate anion, and as such R became a very relevant molecule in detection and function of the acetate anion present in complex biochemical systems.

  5. Synthesis, spectroscopic (FT-IR, FT-Raman, UV and NMR) and computational studies on 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone.

    PubMed

    Arockia doss, M; Savithiri, S; Rajarajan, G; Thanikachalam, V; Saleem, H

    2015-09-01

    The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone (PDPOSC) were made by adopting B3LYP/HF levels theory using 6-311++G(d,p) basis set. The FT-IR and Raman spectra were recorded in solid phase, the fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. DFT method indicates that B3LYP is superior to HF method for molecular vibrational analysis. UV-vis spectrum of the compound was recorded in different solvents in the region of 200-800 nm and the electronic properties such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies were evaluated by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E((2))) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. In addition, MEP and atomic charges of carbon, nitrogen and oxygen were calculated using B3LYP/6-311++G(d,p) level theory. Moreover, thermodynamic properties of the title compound were calculated by B3LYP/HF, levels using 6-311++G(d,p) basis set. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. PMID:25879989

  6. Synthesis, spectroscopic (FT-IR, FT-Raman, UV and NMR) and computational studies on 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone

    NASA Astrophysics Data System (ADS)

    Arockia doss, M.; Savithiri, S.; Rajarajan, G.; Thanikachalam, V.; Saleem, H.

    2015-09-01

    The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone (PDPOSC) were made by adopting B3LYP/HF levels theory using 6-311++G(d,p) basis set. The FT-IR and Raman spectra were recorded in solid phase, the fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. DFT method indicates that B3LYP is superior to HF method for molecular vibrational analysis. UV-vis spectrum of the compound was recorded in different solvents in the region of 200-800 nm and the electronic properties such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies were evaluated by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E(2)) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. In addition, MEP and atomic charges of carbon, nitrogen and oxygen were calculated using B3LYP/6-311++G(d,p) level theory. Moreover, thermodynamic properties of the title compound were calculated by B3LYP/HF, levels using 6-311++G(d,p) basis set. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  7. One new and six known triterpene xylosides from Cimicifuga racemosa: FT-IR, Raman and NMR studies and DFT calculations

    NASA Astrophysics Data System (ADS)

    Jamróz, Marta K.; Jamróz, Michał H.; Cz. Dobrowolski, Jan; Gliński, Jan A.; Gleńsk, Michał

    One new and six known triterpene xylosides were isolated from Cimicifuga racemosa (black cohosh, Actaea racemosa). The structure of a new compound, designated as isocimipodocarpaside (1), was established to be (24S)-3β-hydroxy-24,25-oxiirane-16,23-dione-9,10-seco-9,19-cyclolanost-1(10),7(8),9(11)-trien 3-O-β-D-xylopyranoside, by means of 1H and 13C NMR, IR and Raman spectroscopies and Mass Spectrometry. The six known compounds are: 23-epi-26-deoxycimicifugoside (2), 23-epi-26-deoxyactein (3), 25-anhydrocimigenol xyloside (4), 23-O-acetylshengmanol xyloside (5), 25-O-acetylcimigenol xyloside (6) and 3'-O-acetylcimicifugoside H-1 (7). On the basis of NMR data supported by DFT calculations of NMR shielding constants of (2), its structure, previously described as 26-deoxycimicifugoside was corrected and determined as 23-epi-26-deoxycimicifugoside. The 13C CPMAS NMR spectra of the studied compounds (1)-(7) provided data on their solid-state interactions. The IR and Raman spectra in the Cdbnd O, Cdbnd C, and Csbnd H stretching vibration regions clearly discriminate different triterpenes found in C. racemosa.

  8. Theoretical (DFT) and experimental (FT-IR, FT-Raman, FT-NMR) investigations on 7-Acetoxy-4-(bromomethyl)coumarin

    NASA Astrophysics Data System (ADS)

    Erdogdu, Y.; Saglam, S.; Dereli, Ö.

    2015-09-01

    An analysis of the results of the structural and spectroscopic studies of 7-Acetoxy-4-(bromomethyl) coumarin (7A4BMC) molecule were performed by FT-IR, FT-Raman, FT-NMR and quantum chemical calculations. The FT-IR and FT-Raman spectra of 7A4BMC were recorded in the 400-4000 and 50-3500 cm-1 region, respectively. The molecular conformations of 7A4BMC were computed at the B3LYP/6-311++G(d,p) level of theory. Molecular structure and spectral calculations were calculated by means of B3LYP with 6-311++G(d,p), cc-pVDZ and cc-pVTZ basis sets. The whole vibrational characteristics of the 7A4BMC molecule are given.

  9. FT-IR and C-13 NMR analysis of soil humic fractions from a long term cropping systems study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Increased knowledge of humic fractions is important due to its involvement in many soil ecosystem processes. Soil humic acid (HA) and fulvic acid (FA) from a nine-year agroecosystem study with different tillage, cropping system, and N source treatments were characterized using FT-IR andsolid-state ...

  10. 1H NMR and FT-IR dataset based structural investigation of poly(amic acid)s and polyimides from 4,4′-diaminostilbene

    PubMed Central

    Kumar, Amit; Tateyama, Seiji; Yasaki, Katsuaki; Ali, Mohammad Asif; Takaya, Naoki; Singh, Rajeev; Kaneko, Tatsuo

    2016-01-01

    Structural investigation of polymers by various available analytical methods is important in order to correlate the structure with polymer properties for which understanding of polymer structure is very important factor. The data presented here in this article shows the 1H NMR spectra used for the characterization of prepared poly(amic acid)s (PAAs). It is often difficult to assigns the peak in NMR of polymers due to its complexity. Data presented here helps in assigning the proton peak in complex NMR of PAAs prepared from aromatic diamines. Further functionality in polymer chains can be confirmed by FT-IR spectra. Change in functionality during some reaction or process can be monitored by disappearance or appearance of peaks in FT-IR. The complete imidization of PAAs to Polyimides (PIs) is difficult to analyze because of the chemical stability i.e. insolubility of PIs in most of the solvent therefore the completion of imidization process was confirmed using FTIR. PMID:26933669

  11. Functional groups identified by solid state 13C NMR spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Animal manure is generally high in organic matter intensity so it is well suitable for 13C nuclear magnetic resonance (NMR) analysis. Solid-state 13C NMR techniques used in characterizing organic matter and its components include, but are not limited to, cross-polarization /magic angle spinning (CP...

  12. Whole-core analysis by sup 13 C NMR

    SciTech Connect

    Vinegar, H.J.; Tutunjian, P.N. ); Edelstein, W.A.; Roemer, P.B. )

    1991-06-01

    This paper reports on a whole-core nuclear magnetic resonance (NMR) system that was used to obtain natural abundance {sup 13}C spectra. The system enables rapid, nondestructive measurements of bulk volume of movable oil, aliphatic/aromatic ratio, oil viscosity, and organic vs. carbonate carbon. {sup 13}C NMR can be used in cores where the {sup 1}H NMR spectrum is too broad to resolve oil and water resonances separately. A 5 1/4-in. {sup 13}C/{sup 1}H NMR coil was installed on a General Electric (GE) CSI-2T NMR imager/spectrometer. With a 4-in.-OD whole core, good {sup 13}C signal/noise ratio (SNR) is obtained within minutes, while {sup 1}H spectra are obtained in seconds. NMR measurements have been made of the {sup 13}C and {sup 1}H density of crude oils with a wide range of API gravities. For light- and medium-gravity oils, the {sup 13}C and {sup 1}H signal per unit volume is constant within about 3.5%. For heavy crudes, the {sup 13}C and {sup 1}H density measured by NMR is reduced by the shortening of spin-spin relaxation time. {sup 13}C and {sup 1}H NMR spin-lattice relaxation times were measured on a suite of Cannon viscosity standards, crude oils (4 to 60{degrees} API), and alkanes (C{sub 5} through C{sub 16}) with viscosities at 77{degrees}F ranging from 0.5 cp to 2.5 {times} 10{sup 7} cp. The {sup 13}C and {sup 1}H relaxation times show a similar correlation with viscosity from which oil viscosity can be estimated accurately for viscosities up to 100 cp. The {sup 13}C surface relaxation rate for oils on water-wet rocks is very low. Nonproton decoupled {sup 13}C NMR is shown to be insensitive to kerogen; thus, {sup 13}C NMR measures only the movable hydrocarbon content of the cores. In carbonates, the {sup 13}C spectrum also contains a carbonate powder pattern useful in quantifying inorganic carbon and distinguishing organic from carbonate carbon.

  13. Hydrogen bonds and a hydrogen-bonded chain in mannich bases of 5,5'-dinitro-2,2'-biphenol-FT-IR and 1H NMR studies

    NASA Astrophysics Data System (ADS)

    Brzezinski, Bogumil; Urjasz, Hanna; Bartl, Franz; Zundel, Georg

    1997-11-01

    5,5'-Dinitro-3-diethylaminomethyl-2,2'-biphenol ( 1) and 5,5'-dinitro-3,3' bis(diethylaminomethyl)-2,2'-biphenol ( 2) as well as 5,5'-dinitro-2,2'-biphenol ( 3) were synthesized and studied by FT-IR and 1H NMR spectroscopy in acetonitrile or acetonitrile-d 3 solutions, respectively. With compound 1 a hydrogen-bonded system with large proton polarizability is found. In the hydrogen bonds in compound 2 the protons are localized at the N atoms. These hydrogen bonds show no proton polarizability. In the protonated compound 2 a very strong homoconjugated -O⋯H +⋯O - hydrogen bond with large proton polarizability is found, whereas two other protons are localized at the N atoms. The deviation of the results obtained with other derivatives of 2,2'-biphenols are caused by the larger acidity of the nitro groups.

  14. X-ray, FT-IR, NMR and PM5 structural studies and antibacterial activity of unexpectedly stable salinomycin-benzotriazole intermediate ester

    NASA Astrophysics Data System (ADS)

    Huczyński, Adam; Janczak, Jan; Antoszczak, Michał; Stefańska, Joanna; Brzezinski, Bogumil

    2012-08-01

    The unexpectedly stable benzotriazole ester of salinomycin (SAL-HOBt) - an intermediate product of the amidation reaction of salinomycin has been isolated and structurally characterised (using a single crystal) by X-ray, FT-IR, NMR and semiempirical methods. The results of the X-ray and spectroscopic studies demonstrated that this intermediate ester exist in the solid state and in solution exclusively as the stable O-acyl form. The molecular structure of SAL-HOBt is stabilised by relatively weak intramolecular hydrogen bonds. The PM5 calculation of possible structures of SAL-HOBt has shown that the O-acyl form is more energetically favourable than its N-oxide-N-acyl isomers. The antimicrobial tests show that SAL-HOBt is active against Gram-positive bacteria and clinical isolates methicillin-resistant Staphylococcus aureus (MIC = 1-2 μg/ml).

  15. Dihydroflavanonols from Cedrus deodara, A (13)C NMR study.

    PubMed

    Agrawal, P K; Agarwal, S K; Rastogi, R P; Osterdahal, B G

    1981-09-01

    High resolution (13)C NMR study of taxifolin, cedeodarin, cedrin and their methyl ethers allowed unambiguous placement of the Me in 5,7-dihydroxyflavanonol nucleus, besides providing other valuable information on the substitution pattern in the molecule.

  16. Localized in vivo13C NMR spectroscopy of the brain

    PubMed Central

    Gruetter, Rolf; Adriany, Gregor; Choi, In-Young; Henry, Pierre-Gilles; Lei, Hongxia; Öz, Gülin

    2006-01-01

    Localized 13C NMR spectroscopy provides a new investigative tool for studying cerebral metabolism. The application of 13C NMR spectroscopy to living intact humans and animals presents the investigator with a number of unique challenges. This review provides in the first part a tutorial insight into the ingredients required for achieving a successful implementation of localized 13C NMR spectroscopy. The difficulties in establishing 13C NMR are the need for decoupling of the one-bond 13C–1H heteronuclear J coupling, the large chemical shift range, the low sensitivity and the need for localization of the signals. The methodological consequences of these technical problems are discussed, particularly with respect to (a) RF front-end considerations, (b) localization methods, (c) the low sensitivity, and (d) quantification methods. Lastly, some achievements of in vivo localized 13C NMR spectroscopy of the brain are reviewed, such as: (a) the measurement of brain glutamine synthesis and the feasibility of quantifying glutamatergic action in the brain; (b) the demonstration of significant anaplerotic fluxes in the brain; (c) the demonstration of a highly regulated malate-aspartate shuttle in brain energy metabolism and isotope flux; (d) quantification of neuronal and glial energy metabolism; and (e) brain glycogen metabolism in hypoglycemia in rats and humans. We conclude that the unique and novel insights provided by 13C NMR spectroscopy have opened many new research areas that are likely to improve the understanding of brain carbohydrate metabolism in health and disease. PMID:14679498

  17. FT-IR, FT-Raman, UV, NMR spectra and molecular structure investigation of (E)-2-(3-chloropyrazin-2-yl)-1-(3-ethyl-2, 6-diphenyl piperidin-4-ylidene) hydrazine: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Therasa Alphonsa, A.; Loganathan, C.; Athavan Alias Anand, S.; Kabilan, S.

    2015-11-01

    This work presents the characterization of (E)-2-(3-chloropyrazin-2-yl)-1-(3-ethyl-2, 6-diphenyl piperidin-4-ylidene) hydrazine (HDE) by quantum chemical calculations and spectral techniques. The structure was investigated by FT-IR, FT-Raman, UV-vis and NMR techniques. The geometrical parameters and energies have been obtained from Density functional theory (DFT) B3LYP (6-31G (d, p)) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. 1H and 13C NMR chemical shifts of the molecule were calculated using Gauge-independent atomic orbital method (GIAO). The electronic properties such as excitation energies, wavelength, HOMO, LUMO energies performed by Time dependent density functional theory (TD-DFT) results complements with the experimental findings. NBO analysis has been performed for analyzing charge delocalization throughout the molecule. The calculation results were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. To provide information about the interactions between human cytochrome protein and the novel compound theoretically, docking studies were carried out using Schrödinger software.

  18. HOMO-LUMO, UV, NLO, NMR and vibrational analysis of 3-methyl-1-phenylpyrazole using FT-IR, FT-RAMAN FT-NMR spectra and HF-DFT computational methods.

    PubMed

    Carthigayan, K; Xavier, S; Periandy, S

    2015-05-01

    In this paper, the spectral analysis of 3-methyl-1-phenylpyrazole is carried out using the FT-IR, FT Raman, FT NMR and UV-Vis spectra with the help of quantum mechanical computations using HF and density functional theories. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G (d,p) basis set and the most stable conformer with minimum energy was identified and the same conformer was used for further computations. The computed wave numbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both HF and B3LYP methods with 6-311+G (d,p) and 6-311++G (d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for (1)H and (13)C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated. PMID:25710893

  19. HOMO-LUMO, UV, NLO, NMR and vibrational analysis of 3-methyl-1-phenylpyrazole using FT-IR, FT-RAMAN FT-NMR spectra and HF-DFT computational methods.

    PubMed

    Carthigayan, K; Xavier, S; Periandy, S

    2015-05-01

    In this paper, the spectral analysis of 3-methyl-1-phenylpyrazole is carried out using the FT-IR, FT Raman, FT NMR and UV-Vis spectra with the help of quantum mechanical computations using HF and density functional theories. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G (d,p) basis set and the most stable conformer with minimum energy was identified and the same conformer was used for further computations. The computed wave numbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both HF and B3LYP methods with 6-311+G (d,p) and 6-311++G (d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for (1)H and (13)C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated.

  20. Quantum mechanical study and spectroscopic (FT-IR, FT-Raman, 13C, 1H, UV) study, first order hyperpolarizability, NBO analysis, HOMO and LUMO analysis of 4-[(4-aminobenzene) sulfonyl] aniline by ab initio HF and density functional method

    NASA Astrophysics Data System (ADS)

    Muthu, S.; Uma Maheswari, J.

    The Fourier transform infrared (FT-IR) and FT-Raman of 4-[(4-aminobenzene) sulfonyl] aniline have been recorded and analyzed. The equilibrium geometry, harmonic vibrational frequencies have been investigated with the help of HF and DFT methods with 6-31G(d,p) as basis set. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The linear polarizability (α) and the first order hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. UV-vis spectrum of the compound was recorded and electronic properties, such as HOMO and LUMO energies were also performed. Finally the calculations results were applied to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra.

  1. A 13C-NMR study of azacryptand complexes.

    PubMed

    Wild, Aljoscha A C; Fennell, Kevin; Morgan, Grace G; Hewage, Chandralal M; Malthouse, J Paul G

    2014-09-28

    An azacryptand has been solubilised in aqueous media containing 50% (v/v) dimethyl sulphoxide. (13)C-NMR has been used to determine how the azacryptand is affected by zinc binding at pH 10. Using (13)C-NMR and (13)C-enriched bicarbonate we have been able to observe the formation of 4 different carbamate derivatives of the azacryptand at pH 10. The azacryptand was shown to solubilise zinc or cadmium at alkaline pHs. Two moles of zinc are bound per mole of azacryptand and this complex binds 1 mole of carbonate. By replacing the zinc with cadmium-113 we have shown that the (13)C-NMR signal of the (13)C-enriched carbon of the bound carbonate is split into two triplets at 2.2 °C. This shows that two cadmium complexes are formed and in each of these complexes the carbonate group is bound by two magnetically equivalent metal ions. It also demonstrates that these cadmium complexes are not in fast exchange. From temperature studies we show that in the zinc complexes both complexes are in fast exchange with each other but are in slow exchange with free bicarbonate. HOESY is used to determine the position of the carbonate carbon in the complex. The solution and crystal structures of the zinc-carbonate-azacryptand complexes are compared. PMID:25091182

  2. 13C NMR spectra of pyridine chalcone analogs

    NASA Astrophysics Data System (ADS)

    Jovanović, B. Ž.; Mišić-Vuković, M.; Marinković, A. D.; Csanádi, J.

    1999-05-01

    13C NMR spectra of two series of pyridine chalcone analogs were determined in deuterated dimethylsulphoxide (DMSO-d 6). It was established that these compounds were in more stable E-configurations except for the 4-pyridalacetophenone which was in Z-configuration. On the basis of the Hammett correlations of 13C NMR chemical shifts of the ethylenic bond carbon atoms and the σ values for the pyridine "aza" groups, the polarization of ethylenic bonds were discussed. It was established that the opposite effect of the pyridine substituents at the electronic density distribution in pyridalacetophenone and cinnamoylpyridines depends on its direct bonding to the ethylenic carbon or the transmission electronic effects via the carbonyl group, respectively.

  3. Characterization studies and cytotoxicity assays of Pt(II) and Pd(II) dithiocarbamate complexes by means of FT-IR, NMR spectroscopy and mass spectrometry.

    PubMed

    Alverdi, V; Giovagnini, L; Marzano, C; Seraglia, R; Bettio, F; Sitran, S; Graziani, R; Fregona, D

    2004-06-01

    The precursors [M(ESDTM)Cl(2)] (M=Pt(II), Pd(II); ESDTM=EtO(2)CCH(2)(CH(3))NCS(2)Me, S-methyl(ethylsarcosinedithiocarbamate)) were synthesized as previously reported [J. Inorg. Biochem. 83 (2001) 31] and used to obtain [M(ESDT)Cl](n) (ESDT=ethylsarcosinedithiocarbamate anion) species. The complexes formed through reaction between [M(ESDT)Cl](n) and the two chiral amino-alcohols synephryne (Syn) and norphenylephrine (Nor) have been synthesized, with the ultimate goal of preparing mixed dithiocarbamate/amino metal complexes of the type [M(ESDT)(Am)Cl] (Am=Syn, Nor). These compounds have been isolated, purified and characterized by means of FT-IR, mono- and bidimensional NMR spectroscopy and mass spectrometry ESI/MS (electronspray mass spectra). The experimental data suggest that in all cases coordination of the dithiocarbamate ligand (ESDT) takes a place through the two sulfur atoms, the -NCSS moiety acting as a symmetrical bidentate chelating group, in a square-planar geometry around the M(II) ion, while the other two coordination positions are occupied by the chlorine atom and the amino-alcohol ligand, respectively. In particular, synephrine and norphenylephrine appear to be bound to the metal atom through the amino nitrogen atom by means of a dative bond. Finally, the biological activity of the new complexes has been studied by MTT (tetrazolio salt reduction) test and by detecting the inhibition of DNA synthesis and of clonal growth in various cancer cell lines. All Pd(II) derivatives showed a noticeable activity very close to that of cisplatin, used as reference drug. Moreover, they showed significantly reduced cross-resistance to cisplatin in a pair of cell lines (2008/C13*) with known acquired cisplatin resistance mechanisms. PMID:15149823

  4. An experimental and theoretical investigation of Acenaphthene-5-boronic acid: conformational study, NBO and NLO analysis, molecular structure and FT-IR, FT-Raman, NMR and UV spectra.

    PubMed

    Karabacak, Mehmet; Sinha, Leena; Prasad, Onkar; Asiri, Abdullah M; Cinar, Mehmet

    2013-11-01

    The solid state Fourier transform infrared (FT-IR) and FT-Raman spectra of Acenaphthene-5-boronic acid (AN-5-BA), have been recorded in the range 4000-400cm(-1) and 4000-10cm(-1), respectively. Density functional theory (DFT), with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the molecule. The vibrational wave numbers and their assignments were examined theoretically using the Gaussian 09 set of quantum chemistry codes and the normal modes were assigned by a scaled quantum mechanical (SQM) force field approach. Hydrogen-bonded dimer of AN-5-BA, optimized by counterpoise correction, has also been studied by B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge-Including Atomic Orbital (GIAO) method. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV spectrum of the title compound was also recorded and the electronic properties, such as frontier orbitals, and band gap energies were measured by TD-DFT approach. The first order hyperpolarizability 〈β〉, its components and associated properties such as average polarizability and anisotropy of the polarizability (α and Δα) of AN-5-BA was calculated using the finite-field approach. PMID:23892116

  5. An experimental and theoretical investigation of Acenaphthene-5-boronic acid: Conformational study, NBO and NLO analysis, molecular structure and FT-IR, FT-Raman, NMR and UV spectra

    NASA Astrophysics Data System (ADS)

    Karabacak, Mehmet; Sinha, Leena; Prasad, Onkar; Asiri, Abdullah M.; Cinar, Mehmet

    2013-11-01

    The solid state Fourier transform infrared (FT-IR) and FT-Raman spectra of Acenaphthene-5-boronic acid (AN-5-BA), have been recorded in the range 4000-400 cm-1 and 4000-10 cm-1, respectively. Density functional theory (DFT), with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the molecule. The vibrational wave numbers and their assignments were examined theoretically using the Gaussian 09 set of quantum chemistry codes and the normal modes were assigned by a scaled quantum mechanical (SQM) force field approach. Hydrogen-bonded dimer of AN-5-BA, optimized by counterpoise correction, has also been studied by B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge-Including Atomic Orbital (GIAO) method. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV spectrum of the title compound was also recorded and the electronic properties, such as frontier orbitals, and band gap energies were measured by TD-DFT approach. The first order hyperpolarizability <β>, its components and associated properties such as average polarizability and anisotropy of the polarizability (α and Δα) of AN-5-BA was calculated using the finite-field approach.

  6. The structure elucidation of mequindox and 1,4-bisdesoxymequindox: NMR analyses, FT-IR spectra, DFT calculations and thermochemical studies

    NASA Astrophysics Data System (ADS)

    Zhang, Jiaheng; He, Xin; Gao, Haixiang

    2011-10-01

    In the current work, we report a combined experimental and theoretical study on the molecular conformation, vibrational spectra, and nuclear magnetic resonance (NMR) spectra of mequindox (MEQ) and 1,4-bisdesoxymequindox (1,4-BDM). The geometric structure and vibrational frequencies of MEQ and 1,4-BDM have been calculated by density functional theory employing the B3LYP functional and 6-311++G(d,p) basis set. The 1H and 13C NMR chemical shifts have been calculated by gauge-including atomic orbital method with B3LYP 6-311++G(2df,2pd) approach. The calculation results have been applied to simulate the infrared and NMR spectra of the compounds. The theoretical results agree well with the observed spectra. The bond dissociation enthalpy of MEQ and the heat of formation of MEQ and 1,4-BDM have also been computed.

  7. Quantum mechanical study of the structure and spectroscopic (FT-IR, FT-Raman, 13C, 1H and UV), NBO and HOMO-LUMO analysis of 2-quinoxaline carboxylic acid

    NASA Astrophysics Data System (ADS)

    Prabavathi, N.; Nilufer, A.; Krishnakumar, V.

    The FTIR and FT-Raman spectra of 2-quinoxaline carboxylic acid (2-QCA) has been recorded in the region 4000-450 and 4000-100 cm-1, respectively. The conformational analysis, optimized geometry, frequency and intensity of the vibrational bands of 2-QCA were obtained by the density functional theory (DFT) with complete relaxation in the potential energy surface using 6-31G(d) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The 1H and13C NMR spectra have been recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were also calculated using the gauge independent atomic orbital (GIAO) method and their respective linear correlations were obtained. The theoretical UV-visible spectrum of the compound using CIS method and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The Mulliken charges, the values of electric dipole moment (μ) of the molecule were computed using DFT calculations. The change in electron density (ED) in the σ* antibonding orbitals and stabilization energies E(2) have been calculated by natural bond (NBO) analysis to give clear evidence of stabilization originating in the hyper conjugation of hydrogen-bonded interactions.

  8. Dipolar-coupling-mediated total correlation spectroscopy in solid-state 13C NMR: Selection of individual 13C- 13C dipolar interactions

    NASA Astrophysics Data System (ADS)

    Spano, Justin; Wi, Sungsool

    2010-06-01

    Herein is described a useful approach in solid-state NMR, for selecting homonuclear 13C- 13C spin pairs in a multiple- 13C homonuclear dipolar coupled spin system. This method builds upon the zero-quantum (ZQ) dipolar recoupling method introduced by Levitt and coworkers (Marin-Montesinos et al., 2006 [30]) by extending the originally introduced one-dimensional (1D) experiment into a two-dimensional (2D) method with selective irradiation scheme, while moving the 13C- 13C mixing scheme from the transverse to the longitudinal mode, together with a dramatic improvement in the proton decoupling efficiency. Selective spin-pair recoupling experiments incorporating Gaussian and cosine-modulated Gaussian pulses for inverting specific spins were performed, demonstrating the ability to detect informative, simplified/individualized, long-range 13C- 13C homonuclear dipolar coupling interactions more accurately by removing less informative, stronger, short-range 13C- 13C interactions from 2D correlation spectra. The capability of this new approach was demonstrated experimentally on uniformly 13C-labeled Glutamine and a tripeptide sample, GAL.

  9. QM/MM methodology, docking and spectroscopic (FT-IR/FT-Raman, NMR, UV) and Fukui function analysis on adrenergic agonist.

    PubMed

    Uma Maheswari, J; Muthu, S; Sundius, Tom

    2015-02-25

    The Fourier transform infrared, FT-Raman, UV and NMR spectra of Ternelin have been recorded and analyzed. Harmonic vibrational frequencies have been investigated with the help of HF with 6-31G (d,p) and B3LYP with 6-31G (d,p) and LANL2DZ basis sets. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. The polarizability (α) and the first hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. Stability of the molecule arising from hyper conjugative interactions, and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in Ternelin. Finally the calculated results were compared to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. Molecular docking studies have been carried out in the active site of Ternelin and reactivity with ONIOM was also investigated. PMID:25277632

  10. QM/MM methodology, docking and spectroscopic (FT-IR/FT-Raman, NMR, UV) and Fukui function analysis on adrenergic agonist

    NASA Astrophysics Data System (ADS)

    Uma Maheswari, J.; Muthu, S.; Sundius, Tom

    2015-02-01

    The Fourier transform infrared, FT-Raman, UV and NMR spectra of Ternelin have been recorded and analyzed. Harmonic vibrational frequencies have been investigated with the help of HF with 6-31G (d,p) and B3LYP with 6-31G (d,p) and LANL2DZ basis sets. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by GIAO method. The polarizability (α) and the first hyperpolarizability (β) values of the investigated molecule have been computed using DFT quantum mechanical calculations. Stability of the molecule arising from hyper conjugative interactions, and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The electron density-based local reactivity descriptors such as Fukui functions were calculated to explain the chemical selectivity or reactivity site in Ternelin. Finally the calculated results were compared to simulated infrared and Raman spectra of the title compound which show good agreement with observed spectra. Molecular docking studies have been carried out in the active site of Ternelin and reactivity with ONIOM was also investigated.

  11. Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule

    NASA Astrophysics Data System (ADS)

    Gökce, Halil; Öztürk, Nuri; Ceylan, Ümit; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2016-06-01

    In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311 ++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data.

  12. Biosynthetic uniform 13C,15N-labelling of zervamicin IIB. Complete 13C and 15N NMR assignment.

    PubMed

    Ovchinnikova, Tatyana V; Shenkarev, Zakhar O; Yakimenko, Zoya A; Svishcheva, Natalia V; Tagaev, Andrey A; Skladnev, Dmitry A; Arseniev, Alexander S

    2003-01-01

    Zervamicin IIB is a member of the alpha-aminoisobutyric acid containing peptaibol antibiotics. A new procedure for the biosynthetic preparation of the uniformly 13C- and 15N-enriched peptaibol is described This compound was isolated from the biomass of the fungus-producer Emericellopsis salmosynnemata strain 336 IMI 58330 obtained upon cultivation in the totally 13C, 15N-labelled complete medium. To prepare such a medium the autolysed biomass and the exopolysaccharides of the obligate methylotrophic bacterium Methylobacillus flagellatus KT were used. This microorganism was grown in totally 13C, 15N-labelled minimal medium containing 13C-methanol and 15N-ammonium chloride as the only carbon and nitrogen sources. Preliminary NMR spectroscopic analysis indicated a high extent of isotope incorporation (> 90%) and led to the complete 13C- and 15N-NMR assignment including the stereospecific assignment of Aib residues methyl groups. The observed pattern of the structurally important secondary chemical shifts of 1H(alpha), 13C=O and 13C(alpha) agrees well with the previously determined structure of zervamicin IIB in methanol solution. PMID:14658801

  13. Electronic [UV-Visible] and vibrational [FT-IR, FT-Raman] investigation and NMR-mass spectroscopic analysis of terephthalic acid using quantum Gaussian calculations

    NASA Astrophysics Data System (ADS)

    Karthikeyan, N.; Joseph Prince, J.; Ramalingam, S.; Periandy, S.

    2015-03-01

    In this research work, the vibrational IR, polarization Raman, NMR and mass spectra of terephthalic acid (TA) were recorded. The observed fundamental peaks (IR, Raman) were assigned according to their distinctiveness region. The hybrid computational calculations were carried out for calculating geometrical and vibrational parameters by DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The molecular mass spectral data related to base molecule and substitutional group of the compound was analyzed. The modification of the chemical property by the reaction mechanism of the injection of dicarboxylic group in the base molecule was investigated. The 13C and 1H NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by hybrid Gaussian calculation methods. The orbital energies of different levels of HOMO and LUMO were calculated and the molecular orbital lobe overlapping showed the inter charge transformation between the base molecule and ligand group. From the frontier molecular orbitals (FMO), the possibility of electrophilic and nucleophilic hit also analyzed. The NLO activity of the title compound related to Polarizability and hyperpolarizability were also discussed. The present molecule was fragmented with respect to atomic mass and the mass variation depends on the substitutions have also been studied.

  14. Electronic [UV-Visible] and vibrational [FT-IR, FT-Raman] investigation and NMR-mass spectroscopic analysis of terephthalic acid using quantum Gaussian calculations.

    PubMed

    Karthikeyan, N; Prince, J Joseph; Ramalingam, S; Periandy, S

    2015-03-15

    In this research work, the vibrational IR, polarization Raman, NMR and mass spectra of terephthalic acid (TA) were recorded. The observed fundamental peaks (IR, Raman) were assigned according to their distinctiveness region. The hybrid computational calculations were carried out for calculating geometrical and vibrational parameters by DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the corresponding results were tabulated. The molecular mass spectral data related to base molecule and substitutional group of the compound was analyzed. The modification of the chemical property by the reaction mechanism of the injection of dicarboxylic group in the base molecule was investigated. The (13)C and (1)H NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method and the absolute chemical shifts related to TMS were compared with experimental spectra. The study on the electronic and optical properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by hybrid Gaussian calculation methods. The orbital energies of different levels of HOMO and LUMO were calculated and the molecular orbital lobe overlapping showed the inter charge transformation between the base molecule and ligand group. From the frontier molecular orbitals (FMO), the possibility of electrophilic and nucleophilic hit also analyzed. The NLO activity of the title compound related to Polarizability and hyperpolarizability were also discussed. The present molecule was fragmented with respect to atomic mass and the mass variation depends on the substitutions have also been studied.

  15. Stable isotope-enhanced two- and three-dimensional diffusion ordered 13C-NMR spectroscopy (SIE-DOSY 13C-NMR)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable Isotope-Enhanced Diffusion Ordered (SIE-DOSY) 13C-NMR has been applied to 13C-enriched carbohydrates and has been used to determine diffusion coefficients for pentose and hexose monosaccharides, a disaccharide and a trisaccharide. These 2D spectra were obtained with as little as 8 min of acq...

  16. (13)C NMR assignments of regenerated cellulose from solid-state 2D NMR spectroscopy.

    PubMed

    Idström, Alexander; Schantz, Staffan; Sundberg, Johan; Chmelka, Bradley F; Gatenholm, Paul; Nordstierna, Lars

    2016-10-20

    From the assignment of the solid-state (13)C NMR signals in the C4 region, distinct types of crystalline cellulose, cellulose at crystalline surfaces, and disordered cellulose can be identified and quantified. For regenerated cellulose, complete (13)C assignments of the other carbon regions have not previously been attainable, due to signal overlap. In this study, two-dimensional (2D) NMR correlation methods were used to resolve and assign (13)C signals for all carbon atoms in regenerated cellulose. (13)C-enriched bacterial nanocellulose was biosynthesized, dissolved, and coagulated as highly crystalline cellulose II. Specifically, four distinct (13)C signals were observed corresponding to conformationally different anhydroglucose units: two signals assigned to crystalline moieties and two signals assigned to non-crystalline species. The C1, C4 and C6 regions for cellulose II were fully examined by global spectral deconvolution, which yielded qualitative trends of the relative populations of the different cellulose moieties, as a function of wetting and drying treatments. PMID:27474592

  17. NMR structure analysis of uniformly 13C-labeled carbohydrates.

    PubMed

    Fontana, Carolina; Kovacs, Helena; Widmalm, Göran

    2014-06-01

    In this study, a set of nuclear magnetic resonance experiments, some of them commonly used in the study of (13)C-labeled proteins and/or nucleic acids, is applied for the structure determination of uniformly (13)C-enriched carbohydrates. Two model substances were employed: one compound of low molecular weight [(UL-(13)C)-sucrose, 342 Da] and one compound of medium molecular weight ((13)C-enriched O-antigenic polysaccharide isolated from Escherichia coli O142, ~10 kDa). The first step in this approach involves the assignment of the carbon resonances in each monosaccharide spin system using the anomeric carbon signal as the starting point. The (13)C resonances are traced using (13)C-(13)C correlations from homonuclear experiments, such as (H)CC-CT-COSY, (H)CC-NOESY, CC-CT-TOCSY and/or virtually decoupled (H)CC-TOCSY. Based on the assignment of the (13)C resonances, the (1)H chemical shifts are derived in a straightforward manner using one-bond (1)H-(13)C correlations from heteronuclear experiments (HC-CT-HSQC). In order to avoid the (1) J CC splitting of the (13)C resonances and to improve the resolution, either constant-time (CT) in the indirect dimension or virtual decoupling in the direct dimension were used. The monosaccharide sequence and linkage positions in oligosaccharides were determined using either (13)C or (1)H detected experiments, namely CC-CT-COSY, band-selective (H)CC-TOCSY, HC-CT-HSQC-NOESY or long-range HC-CT-HSQC. However, due to the short T2 relaxation time associated with larger polysaccharides, the sequential information in the O-antigen polysaccharide from E. coli O142 could only be elucidated using the (1)H-detected experiments. Exchanging protons of hydroxyl groups and N-acetyl amides in the (13)C-enriched polysaccharide were assigned by using HC-H2BC spectra. The assignment of the N-acetyl groups with (15)N at natural abundance was completed by using HN-SOFAST-HMQC, HNCA, HNCO and (13)C-detected (H)CACO spectra.

  18. NMR structure analysis of uniformly 13C-labeled carbohydrates.

    PubMed

    Fontana, Carolina; Kovacs, Helena; Widmalm, Göran

    2014-06-01

    In this study, a set of nuclear magnetic resonance experiments, some of them commonly used in the study of (13)C-labeled proteins and/or nucleic acids, is applied for the structure determination of uniformly (13)C-enriched carbohydrates. Two model substances were employed: one compound of low molecular weight [(UL-(13)C)-sucrose, 342 Da] and one compound of medium molecular weight ((13)C-enriched O-antigenic polysaccharide isolated from Escherichia coli O142, ~10 kDa). The first step in this approach involves the assignment of the carbon resonances in each monosaccharide spin system using the anomeric carbon signal as the starting point. The (13)C resonances are traced using (13)C-(13)C correlations from homonuclear experiments, such as (H)CC-CT-COSY, (H)CC-NOESY, CC-CT-TOCSY and/or virtually decoupled (H)CC-TOCSY. Based on the assignment of the (13)C resonances, the (1)H chemical shifts are derived in a straightforward manner using one-bond (1)H-(13)C correlations from heteronuclear experiments (HC-CT-HSQC). In order to avoid the (1) J CC splitting of the (13)C resonances and to improve the resolution, either constant-time (CT) in the indirect dimension or virtual decoupling in the direct dimension were used. The monosaccharide sequence and linkage positions in oligosaccharides were determined using either (13)C or (1)H detected experiments, namely CC-CT-COSY, band-selective (H)CC-TOCSY, HC-CT-HSQC-NOESY or long-range HC-CT-HSQC. However, due to the short T2 relaxation time associated with larger polysaccharides, the sequential information in the O-antigen polysaccharide from E. coli O142 could only be elucidated using the (1)H-detected experiments. Exchanging protons of hydroxyl groups and N-acetyl amides in the (13)C-enriched polysaccharide were assigned by using HC-H2BC spectra. The assignment of the N-acetyl groups with (15)N at natural abundance was completed by using HN-SOFAST-HMQC, HNCA, HNCO and (13)C-detected (H)CACO spectra. PMID:24771296

  19. Synthesis, spectral (FT-IR, UV-visible, NMR) features, biological activity prediction and theoretical studies of 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione and its tautomer

    NASA Astrophysics Data System (ADS)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj; Manjula, P. S.; Sarojini, B. K.; Narayana, B.

    2016-03-01

    Triazole compounds constitute an important class of organic chemistry due to their various biological and corrosion inhibition activities. The synthesis scheme of a new triazole compound namely, 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione (4AHT) has been theoretically analyzed. Our density functional theory (DFT) based calculations show that the synthesis of 4AHT is energetically feasible at the room temperature as the reaction is exothermic, spontaneous as well as favored in forward direction. The calculated bond-lengths are found to be in good agreement with corresponding crystallographic values. We have considered two possible tautomers of 4AHT viz. thione and thiol forms. The FT-IR (KBr disc), UV-visible (ethanol) and 1H-NMR (DMSO) spectra of 4AHT have been recorded. The vibrational modes have been assigned on the basis of their potential energy distributions and scaled wavenumbers agree well with the FT-IR wavenumbers. Time dependent DFT calculations are performed to analyze the electronic transitions for various excited states which reproduce the experimental peak observed in UV-visible spectrum. Using gauge independent atomic orbital method 1H-NMR chemical shifts have been calculated and correlated with the experimental chemical shifts with the linear correlation coefficient of 0.9453. Our spectral analyses reveal the dominance of thione over thiol form of 4AHT. The chemical reactivity of 4AHT has been discussed by molecular electrostatic potential surface as well as various electronic parameters. The biological activities of 4AHT have also been explored theoretically and it has been found that the title molecule can act as a potential inhibitor of cyclin-dependent kinase 5 enzyme. These findings may guide the synthesis and design of new triazole compounds with interesting biological activity.

  20. Pulsed polarization transfer for 13C NMR in solids

    NASA Astrophysics Data System (ADS)

    Bax, Ad; Szeverenyi, Nikolaus M.; Maciel, Gary E.

    A new pulsed polarization transfer experiment method is described for the polarization of 13C spins in a solid by magnetization transfer from protons. The method is directly analogous to the INEPT sequence for liquids introduced by Freeman and Morris. As polarization is transferred in PPT between individual 1H 13C pairs, rather than between spin reservoirs, different opportunities exist for structurally selective experiments. Results on p-diethoxybenzene and coronene are presented.

  1. Labeling strategies for 13C-detected aligned-sample solid-state NMR of proteins

    NASA Astrophysics Data System (ADS)

    Filipp, Fabian V.; Sinha, Neeraj; Jairam, Lena; Bradley, Joel; Opella, Stanley J.

    2009-12-01

    13C-detected solid-state NMR experiments have substantially higher sensitivity than the corresponding 15N-detected experiments on stationary, aligned samples of isotopically labeled proteins. Several methods for tailoring the isotopic labeling are described that result in spatially isolated 13C sites so that dipole-dipole couplings among the 13C are minimized, thus eliminating the need for homonuclear 13C- 13C decoupling in either indirect or direct dimensions of one- or multi-dimensional NMR experiments that employ 13C detection. The optimal percentage for random fractional 13C labeling is between 25% and 35%. Specifically labeled glycerol and glucose can be used at the carbon sources to tailor the isotopic labeling, and the choice depends on the resonances of interest for a particular study. For investigations of the protein backbone, growth of the bacteria on [2- 13C]-glucose-containing media was found to be most effective.

  2. NMR at cryogenic temperatures: A {sup 13}C NMR study of ferrocene

    SciTech Connect

    Orendt, A.M.; Facelli, J.C.; Jiang, Y.J.; Grant, D.M.

    1998-09-24

    A new cryogenic apparatus is described that can be used to obtain NMR spectra at temperatures down to 8--10 K. The static solid {sup 13}C NMR spectrum of ferrocene is recorded at that temperature. Spectra recorded at higher temperatures show that ferrocene is still freely rotating about its 5-fold symmetry axis on the {sup 13}C NMR time scale at 45--50 K. A comparison of the principal values of the {sup 13}C chemical-shift tensor obtained from the room- and low-temperature spectra of ferrocene indicates that the lowest frequency chemical shift principal component, {delta}{sub 33}, is tilted off this symmetry axis by approximately 12{degree}. Quantum chemical calculations of the chemical-shift tensor, completed on structures of ferrocene from the literature as well as on optimized structures with the cyclopentadienyl rings locked in both the staggered and eclipsed arrangements, predict the angle between the {delta}{sub 33} direction and the rotation axis to be between 11 and 15{degree}, depending upon the geometry used in the calculation. The calculations also predict the sign of the angular perturbation, information not obtained from the experiment. An explanation of this angular change in the {delta}{sub 33} direction is provided by the composition of the molecular orbitals.

  3. Determination of de novo synthesized amino acids in cellular proteins revisited by 13C NMR spectroscopy.

    PubMed

    Flögel, U; Willker, W; Leibfritz, D

    1997-04-01

    13C nuclear magnetic resonance spectroscopy was used to determine the absolute amounts to de novo synthesized amino acids in both the perchloric acid extracts and the hydrolyzed protein fractions of F98 glioma cells incubated for 2 h with 5 mmol/l [U-13C]glucose. 13C NMR spectra of the hydrolyzed protein fraction revealed a marked incorporation of 13C-labelled alanine, aspartate and glutamate into the proteins of F98 cells within the incubation period. Additionally, small amounts of 13C-labelled glycine, proline and serine could unambiguously be identified in the protein fraction. Astonishingly, approximately equal amounts of 13C-labelled glutamate and aspartate were incorporated into the cellular proteins, although the cytosolic steady-state concentration of aspartate was below 13C NMR detectability. Hypertonic stress decreased the incorporation of 13C-labelled amino acids into the total protein, albeit their cytosolic concentrations were increased, which reflects an inhibition of protein synthesis under these conditions. On the other hand, hypotonic stress increased the amount of 13C-labelled proline incorporated into the cellular proteins even though the cytosolic concentration of 13C-labelled proline was largely decreased. Apparently, hypoosmotic conditions stimulate the synthesis of proteins or peptides with a high proline content. The results show that already after 2 h of incubation with [U-13C]glucose there is a pronounced flux of 13C label into the cellular proteins, which is usually disregarded if cytosolic fluids are examined only. This means that calculations of metabolic fluxes based on 13C NMR spectroscopic data obtained from perchloric acid extracts of cells or tissues and also from in vivo measurements consider only the labelled 'NMR visible' cytosolic metabolites, which may have to be corrected for fast label flowing off into other compartments.

  4. Elucidating proline dynamics in spider dragline silk fibre using 2H-13C HETCOR MAS NMR.

    PubMed

    Shi, Xiangyan; Yarger, Jeffery L; Holland, Gregory P

    2014-05-14

    (2)H-(13)C HETCOR MAS NMR is performed on (2)H/(13)C/(15)N-Pro enriched A. aurantia dragline silk. Proline dynamics are extracted from (2)H NMR line shapes and T1 in a site-specific manner to elucidate the backbone and side chain molecular dynamics for the MaSp2 GPGXX β-turn regions for spider dragline silk in the dry and wet, supercontracted states.

  5. Coal structure at reactive sites by sup 1 H- sup 13 C- sup 19 F double cross polarization (DCP)/MAS sup 13 C NMR spectroscopy

    SciTech Connect

    Hagaman, E.W.; Woody, M.C. )

    1989-01-01

    The solid state NMR technique, {sup 1}H-{sup 13}C-{sup 31}P double cross polarization (DCP)/MAS {sup 13}C-NMR spectroscopy, uses the direct dipolar interaction between {sup 13}C-{sup 31}P spin pairs in organophosphorus substances to identify the subset of carbons within a spherical volume element of 0.4 nm radius centered on the {sup 31}P atom. In combination with chemical manipulation of coals designed to introduce phosphorus containing functionality into the organic matrix, the NMR experiment becomes a method to examine selectively the carbon bonding network at the reactive sites in the coal. This approach generates a statistical structure description of the coal at the reaction centers in contrast to bulk carbon characterization using conventional {sup 1}H-{sup 13}C CP/MAS {sup 13}C NMR spectroscopy. 3 refs.

  6. Molecular structure, spectroscopic (FT-IR, FT-Raman, NMR, UV) studies and first-order molecular hyperpolarizabilities of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine by density functional method

    NASA Astrophysics Data System (ADS)

    Subramanian, N.; Sundaraganesan, N.; Jayabharathi, J.

    2010-07-01

    Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine [vanillin azine (VA)] were carried out by using density functional (DFT/B3LYP) method with 6-31G(d) as basis set. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from solid phase FT-IR and FT-Raman spectra are assigned based on the results of the theoretical calculations. The observed spectra are found to be in good agreement with calculated values. The electric dipole moment ( μ) and the first hyperpolarizability ( β) values of the investigated molecule have been computed using ab initio quantum mechanical calculations. The calculation results also show that the VA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the infrared and Raman spectra of VA was also reported. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The theoretical NMR chemical shifts complement with experimentally measured ones.

  7. Insights into the metabolic response to traumatic brain injury as revealed by 13C NMR spectroscopy

    PubMed Central

    Bartnik-Olson, Brenda L.; Harris, Neil G.; Shijo, Katsunori; Sutton, Richard L.

    2013-01-01

    The present review highlights critical issues related to cerebral metabolism following traumatic brain injury (TBI) and the use of 13C labeled substrates and nuclear magnetic resonance (NMR) spectroscopy to study these changes. First we address some pathophysiologic factors contributing to metabolic dysfunction following TBI. We then examine how 13C NMR spectroscopy strategies have been used to investigate energy metabolism, neurotransmission, the intracellular redox state, and neuroglial compartmentation following injury. 13C NMR spectroscopy studies of brain extracts from animal models of TBI have revealed enhanced glycolytic production of lactate, evidence of pentose phosphate pathway (PPP) activation, and alterations in neuronal and astrocyte oxidative metabolism that are dependent on injury severity. Differential incorporation of label into glutamate and glutamine from 13C labeled glucose or acetate also suggest TBI-induced adaptations to the glutamate-glutamine cycle. PMID:24109452

  8. Vibrational spectroscopic (FT-IR, FT-Raman, ¹H NMR and UV) investigations and computational study of 5-nitro-2-(4-nitrobenzyl) benzoxazole.

    PubMed

    Bhagyasree, J B; Varghese, Hema Tresa; Panicker, C Yohannan; Samuel, Jadu; Van Alsenoy, Christian; Bolelli, Kayhan; Yildiz, Ilkay; Aki, Esin

    2013-02-01

    The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-nitro-2-(4-nitrobenzyl) benzoxazole have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of the normal modes of vibrations was done using GAR2PED program. The energy and oscillator strength calculated by time dependent density functional theory almost compliments with experimental findings. Gauge-including atomic orbital (1)H NMR chemical shifts calculations were carried out by using B3LYP functional with 6-31G basis set. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization have been analyzed using NBO analysis. MEP was performed by the DFT method and the predicted infrared intensities and Raman activities have also been reported. The calculated geometrical parameters are in agreement with that of similar derivatives.

  9. Complete assignments of 1H and 13C NMR data for ten phenylpiperazine derivatives.

    PubMed

    Xiao, Zhihui; Yuan, Mu; Zhang, Si; Wu, Jun; Qi, Shuhua; Li, Qingxin

    2005-10-01

    Ten phenylpiperazine derivatives were designed and synthesized. The first complete assignments of (1)H and (13)C NMR chemical shifts for these phenylpiperazine derivatives were achieved by means of 1D and 2D NMR techniques, including (1)H-(1)H COSY, HSQC and HMBC spectra.

  10. Complete assignments of 1H and 13C NMR data for 10 phenylethanoid glycosides.

    PubMed

    Wu, Jun; Huang, Jianshe; Xiao, Qiang; Zhang, Si; Xiao, Zhihui; Li, Qingxin; Long, Lijuan; Huang, Liangmin

    2004-07-01

    Ten phenylethanoid glycosides, including two new ones, isolated from the aerial parts of the mangrove plant Acanthus ilicifolius were identified. The first complete assignments of the 1H and 13C NMR chemical shifts for these glycosides were achieved by means of 2D NMR techniques, including 1H-1H COSY, TOCSY, HSQC and HMBC spectra.

  11. Production and NMR signal optimization of hyperpolarized 13C-labeled amino acids

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Ferguson, Sarah; Kiswandhi, Andhika; Lumata, Lloyd

    Amino acids are targeted nutrients for consumption by cancers to sustain their rapid growth and proliferation. 13C-enriched amino acids are important metabolic tracers for cancer diagnostics using nuclear magnetic resonance (NMR) spectroscopy. Despite this diagnostic potential, 13C NMR of amino acids however is hampered by the inherently low NMR sensitivity of the 13C nuclei. In this work, we have employed a physics technique known as dynamic nuclear polarization (DNP) to enhance the NMR signals of 13C-enriched amino acids. DNP works by transferring the high polarization of electrons to the nuclear spins via microwave irradiation at low temperature and high magnetic field. Using a fast dissolution method in which the frozen polarized samples are dissolved rapidly with superheated water, injectable solutions of 13C-amino acids with highly enhanced NMR signals (by at least 5,000-fold) were produced at room temperature. Factors that affect the NMR signal enhancement levels such as the choice of free radical polarizing agents and sample preparation will be discussed along with the thermal mixing physics model of DNP. The authors would like to acknowledge the support by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  12. 1H and 13C NMR assignments for the cyanine dyes SYBR Safe and thiazole orange.

    PubMed

    Evenson, William E; Boden, Lauren M; Muzikar, Katy A; O'Leary, Daniel J

    2012-12-01

    Analysis of (1)H and (13)C NMR and mass spectral data for the fluorescent nucleic acid stain SYBR Safe indicates that it contains a cyanine-based cationic core structure identical to thiazole orange. The difference between these two compounds is the type of N-substitution on the quinolinium ring system (SYBR Safe, n-Pr; thiazole orange, Me). The (1)H and (13)C NMR resonances for both compounds were assigned on the basis of one- and two-dimensional (COSY, ROESY, HSQC, and HMBC) experiments. The preferred conformation of these compounds was computed by ab initio methods and found to be consistent with the NMR data.

  13. 1H-NMR and 13C-NMR lipid profiles of human renal tissues.

    PubMed

    Tugnoli, V; Bottura, G; Fini, G; Reggiani, A; Tinti, A; Trinchero, A; Tosi, M R

    2003-01-01

    Lipids from human renal tissues are studied by means of (1)H- and (13)C-NMR spectroscopy. The total lipid fractions obtained from healthy kidneys, malignant renal cell carcinomas, and benign oncocytomas are characterized and analyzed to elucidate the main differences between the functional and neoplastic tissues. In all cases the lipid components are well identified. The healthy kidney is characterized by high amounts of triglycerides and the presence of cholesterol in its free form. On the contrary, renal cell carcinomas contain high amounts of cholesterol that are almost completely esterified as oleate, suggesting an intracellular localization of the cholesteryl esters synthesis. Cholesteryl esters are considered markers of renal cell carcinomas, thus supporting recent theories that these compounds play a leading role in cell proliferation. Oncocytomas are particularly rich in phosphatidylcholine and, analogous to the healthy kidney, are completely lacking in cholesteryl esters. Healthy kidneys and oncocytomas appear to have other similarities if compared with renal cell carcinomas: a very high fatty acyl/cholesterol ratio, the presence of dolichols, and a higher grade of unsaturation. The (13)C data suggest a new method for the direct evaluation of the saturated/unsaturated fatty acyl ratio.

  14. Butene concentration prediction in ethylene/propylene/1-butene terpolymers by FT-IR spectroscopy through multivariate statistical analysis and artificial neural networks.

    PubMed

    Marengo, Emilio; Longo, Valentina; Bobba, Marco; Robotti, Elisa; Zerbinati, Orfeo; Di Martino, Silvana

    2009-01-15

    This paper reports the development of calibration models for quality control in the production of ethylene/propylene/1-butene terpolymers by the use of multivariate tools and FT-IR spectroscopy. 1-Butene concentration prediction is achieved in terpolymers by coupling FT-IR spectroscopy to multivariate regression tools. A dataset of 26 terpolymers (14 coming from a constrained experimental design for mixtures, plus 12 terpolymers used for external validation) was analysed by FT-IR spectroscopy. An internal method of "Polimeri Europa" plant, based on (13)C NMR spectroscopy is used to determine the percentage of 1-butene in the samples. Then, different multivariate tools are used for 1-butene concentration prediction based on the FT-IR spectra recorded. Different multivariate calibration methods were explored: principal component regression (PCR), partial least squares (PLS), stepwise OLS regression (SWR) and artificial neural networks (ANNs). The model obtained by back-propagation neural networks turned out to be the best one. The performances of the BP-ANN model were further improved by variable selection procedures based on the calculation of the first derivative of the network. The proposed approach allows the monitoring in real time of the polymer synthesis and the estimation of the characteristics of the product attainable from the concentration of 1-butene.

  15. Characterization of uniformly and atom-specifically 13C-labeled heparin and heparan sulfate polysaccharide precursors using 13C NMR spectroscopy and ESI mass spectrometry

    PubMed Central

    Nguyen, Thao K. N.; Tran, Vy M.; Victor, Xylophone V.; Skalicky, Jack J.; Kuberan, Balagurunathan

    2010-01-01

    The biological actions of heparin and heparan sulfate, two structurally related glycosaminoglycans, depend on the organization of the complex heparanome. Due to the structural complexity of the heparanome, the sequence of variably sulfonated uronic acid and glucosamine residues is usually characterized by the analysis of smaller oligosaccharide and disaccharide fragments. Even characterization of smaller heparin/heparan sulfate oligosaccharide or disaccharide fragments using simple 1D 1H NMR spectroscopy is often complicated by the extensive signal overlap. 13C NMR signals, on the other hand, overlap less and therefore, 13C NMR spectroscopy can greatly facilitate the structural elucidation of the complex heparanome and provide finer insights into the structural basis for biological functions. This is the first report of the preparation of anomeric carbon-specific 13C-labeled heparin/heparan sulfate precursors from the Escherichia coli K5 strain. Uniformly 13C- and 15N-labeled precursors were also produced and characterized by 13C NMR spectroscopy. Mass spectrometric analysis of enzymatically fragmented disaccharides revealed that anomeric carbon-specific labeling efforts resulted in a minor loss/scrambling of 13C in the precursor backbone, whereas uniform labeling efforts resulted in greater than 95% 13C isotope enrichment in the precursor backbone. These labeled precursors provided high-resolution NMR signals with great sensitivity and set the stage for studying the heparanome–proteome interactions. PMID:20832774

  16. A 13C-NMR study of exopolysaccharide synthesis in Rhizobium meliloti Su47 strain

    NASA Astrophysics Data System (ADS)

    Tavernier, P.; Portais, J.-C.; Besson, I.; Courtois, J.; Courtois, B.; Barbotin, J.-N.

    1998-02-01

    Metabolic pathways implied in the synthesis of succinoglycan produced by the Su47 strain of R. meliloti were evaluated by 13C-NMR spectroscopy after incubation with [1{-}13C] or [2{-}13C] glucose. The biosynthesis of this polymer by R. meliloti from glucose occurred by a direct polymerisation of the introduced glucose and by the pentose phosphate pathway. Les voies métaboliques impliquées dans la synthèse du succinoglycane produit par la souche Su47 de R. meliloti ont été évaluées par la spectroscopie de RMN du carbone 13 après incubation des cellules avec du [1{-}13C] ou [2{-}13C] glucose. La biosynthèse de ce polymère à partir du glucose se produit par polymérisation directe du glucose et par la voie des pentoses phosphate.

  17. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids

    NASA Astrophysics Data System (ADS)

    Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-06-01

    We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (ϕ, ψ) in a series of selectively 13C-labeled 40-residue β-amyloid (Aβ1-40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ1-40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16-21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ϕ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine ϕ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of Aβ1-40 fibrils in 4 h or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples.

  18. Dynamic nuclear polarization-enhanced 13C NMR spectroscopy of static biological solids

    PubMed Central

    Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2013-01-01

    We explore the possibility of using dynamic nuclear polarization (DNP) to enhance signals in structural studies of biological solids by solid state NMR without sample spinning. Specifically, we use 2D 13C-13C exchange spectroscopy to probe the peptide backbone torsion angles (ϕ,ψ) in a series of selectively 13C-labeled 40-residue β-amyloid (Aβ1–40) samples, in both fibrillar and non-fibrillar states. Experiments are carried out at 9.39 T and 8 K, using a static double-resonance NMR probe and low-power microwave irradiation at 264 GHz. In frozen solutions of Aβ1–40 fibrils doped with DOTOPA-TEMPO, we observe DNP signal enhancement factors of 16–21. We show that the orientation- and frequency-dependent spin polarization exchange between sequential backbone carbonyl 13C labels can be simulated accurately using a simple expression for the exchange rate, after experimentally determined homogeneous 13C lineshapes are incorporated in the simulations. The experimental 2D 13C-13C exchange spectra place constraints on the ϕ and ψ angles between the two carbonyl labels. Although the data are not sufficient to determine ϕ and ψ uniquely, the data do provide non-trivial constraints that could be included in structure calculations. With DNP at low temperatures, 2D 13C-13C exchange spectra can be obtained from a 3.5 mg sample of Aβ1–40 fibrils in 4 hr or less, despite the broad 13C chemical shift anisotropy line shapes that are observed in static samples. PMID:23562665

  19. 13C-NMR spectra and contact time experiment for Skjervatjern fulvic and humic acids

    USGS Publications Warehouse

    Malcolm, R.L.

    1992-01-01

    The T(CP) and T(1p) time constants for Skjervatjern fulvic and humic acids were determined to be short with T(CP) values ranging from 0.14 ms to 0.53 ms and T(1p) values ranging from 3.3 ms to 5.9 ms. T(CP) or T(1p) time constants at a contact time of 1 ms are favorable for quantification of 13C-NMR spectra. Because of the short T(CP) values, correction factors for signal intensity for various regions of the 13C-NMR spectra would be necessary at contact times greater than 1.1 ms or less than 0.9 ms. T(CP) and T(1p) values have a limited non-homogeneity within Skjervatjern fulvic and humic acids. A pulse delay or repeat time of 700 ms is more than adequate for quantification of these 13C-NMR spectra. Paramagnetic effects in these humic substances are precluded due to low inorganic ash contents, low contents of Fe, Mn, and Co, and low organic free-radical contents. The observed T(CP) values suggest that all the carbon types in Skjervatjern fulvic and humic acids are fully cross-polarized before significant proton relaxation occurs. The 13C-NMR spectra for Skjervatjern fulvic acid is similar to most aquatic fulvic acids as it is predominantly aliphatic, low in aromaticity (fa1 = 24), low in phenolic content, high in carboxyl content, and has no resolution of a methoxyl peak. The 13C-NMR spectra for Skjervatjern humic acid is also similar to most other aquatic humic acids in that it is also predominantly aliphatic, high in aromaticity (fa1 = 38), moderate in phenolic content, moderate in carboxyl content, and has a clear resolution of a methoxyl carbon region. After the consideration of the necessary 13C-NMR experimental conditions, these spectra are considered to be quantitative. With careful consideration of the previously determined 13C-NMR experimental conditions, quantitative spectra can be obtained for humic substances in the future from the HUMEX site. Possible changes in humic substances due to acidification should be determined from 13C-NMR data.

  20. In vivo 13C NMR metabolite profiling: potential for understanding and assessing conifer seed quality.

    PubMed

    Terskikh, Victor V; Feurtado, J Allan; Borchardt, Shane; Giblin, Michael; Abrams, Suzanne R; Kermode, Allison R

    2005-08-01

    High-resolution 13C MAS NMR spectroscopy was used to profile a range of primary and secondary metabolites in vivo in intact whole seeds of eight different conifer species native to North America, including six of the Pinaceae family and two of the Cupressaceae family. In vivo 13C NMR provided information on the total seed oil content and fatty acid composition of the major storage lipids in a non-destructive manner. In addition, a number of monoterpenes were identified in the 13C NMR spectra of conifer seeds containing oleoresin; these compounds showed marked variability in individual seeds of Pacific silver fir within the same seed lot. In imbibed conifer seeds, the 13C NMR spectra showed the presence of considerable amounts of dissolved sucrose presumed to play a protective role in the desiccation-tolerance of seeds. The free amino acids arginine and asparagine, generated as a result of storage protein mobilization, were detected in vivo during seed germination and early seedling growth. The potential for NMR to profile metabolites in a non-destructive manner in single conifer seeds and seed populations is discussed. It is a powerful tool to evaluate seed quality because of its ability to assess reserve accumulation during seed development or at seed maturity; it can also be used to monitor reserve mobilization, which is critical for seedling emergence. PMID:15996983

  1. Topological Constraints on Chain-Folding Structure of Semicrystalline Polymer as Studied by 13C-13C Double Quantum NMR

    NASA Astrophysics Data System (ADS)

    Hong, Youlee; Miyoshi, Toshikazu

    Chain-folding process is a prominent feature of long polymer chains during crystallization. Over the last half century, much effort has been paid to reveal the chain trajectory. Even though various chain-folding models as well as theories of crystallization at molecule levels have been proposed, they could be not reconciled due to the limited experimental evidences. Recent development of double quantum NMR with selective isotope labeling identified the chain-trajectory of 13C labeled isotactic poly(1-butene). The systematic experiments covered a wide range of parameters, i.e. kinetics, concentration, and molecular weight (Mw) . It was demonstrated that i) adjacent re-entry site was invariant as a function of crystallization temperature (Tc) , concentration, andMw, ii) long-range order of adjacent re-entry sequence is independence of kinetics at a given concentration while it decreased with increasing the polymer concentration at a given Tc due to the increased interruption between the chains, and iii) high Mw chains led to the multilayer folded structures in single crystals, but the melt state induced the identical short adjacent sequences of long and short polymer over a wide range of Tc due to the entanglements. The behaviors indicated that the topological restriction plays significant roles in the chain-folding process rather than the kinetics. The proposed framework to control the chain-folding structure presents a new perspective into the chain organization by either the intra- or inter-chain interaction. National Science Foundation Grants DMR-1105829 and 1408855.

  2. Measuring Level Alignment at the Metal–Molecule Interface by In Situ Electrochemical 13C NMR

    SciTech Connect

    Li, Ying; Zelakiewicz, Brian S.; Allison, Thomas C.; Tong, Yu ye J.

    2015-03-16

    A new technique to measure energy-level alignment at a metal–molecule interface between the Fermi level of the metal and the frontier orbitals of the molecule is proposed and experimentally demonstrated. The method, which combines the electrochemistry of organo-ligand-stabilized Au nanoparticles with 13C NMR spectroscopy (i.e. in situ electrochemical NMR), enables measuring both occupied and unoccupied states.

  3. Natural-abundance sup 13 C NMR study of glycogen repletion in human liver and muscle

    SciTech Connect

    Jue, T.; Rothman, D.L.; Tavitian, B.A.; Shulman, R.G. )

    1989-03-01

    Optimizing the surface-coil design and spectral-acquisition parameters has led to the observation of the {sup 13}C NMR natural abundance glycogen signal in man at 2.1 T. Both the human muscle and hepatic glycogen signals can be detected definitively with a time resolution of {approx}13 min. A {sup 1}H/{sup 13}C concentric surface coil was used. The {sup 1}H outer coil was 11 cm in diameter; the {sup 13}C inner coil was 8 cm in diameter. The coils were tuned to 89.3 MHz and 22.4 MHz, respectively. The {sup 1}H coil was used for optimizing field homogeneity (shimming) the magnet and for single-frequency decoupling of the C{sub 1} glycogen signal. Total power deposition from both the transmitter pulse and the continuous wave decoupling did not exceed the Food and Drug Administration guideline of 8 W/kg of tissue. Experiments were done for which healthy subjects returned to the magnets at different times for {sup 13}C NMR measurement. The spectral difference between experiments was within the noise in the C{sub 1} glycogen region. Because of the spectral reproducibility and the signal sensitivity, hepatic glycogen repletion can be followed. Four hours postprandial, hepatic glycogen increases by 3.8 times from the basal fasted state. The hepatic glycogen data correspond directly to previous biopsy results and support the use of {sup 13}C NMR as a noninvasive probe of human metabolism.

  4. Development of a 13C-optimized 1.5-mm high temperature superconducting NMR probe

    NASA Astrophysics Data System (ADS)

    Ramaswamy, Vijaykumar; Hooker, Jerris W.; Withers, Richard S.; Nast, Robert E.; Brey, William W.; Edison, Arthur S.

    2013-10-01

    We report a 1.5-mm NMR probe based on high temperature superconductors operating at 14.1 T optimized for 13C detection. The probe has a total sample volume of about 35 microliters (μL) with an active volume of 20 μL and provides exceptional mass sensitivity for 13C detection. The probe also has excellent 1H sensitivity and employs a 2H lock; 15N irradiation capability can be added in the future. The coils are cooled to about 20 K using a standard Agilent cryogenic refrigeration system, and the sample temperature is regulated near room temperature. The coil design considerations are discussed in detail. This probe is ideal for directly detected 13C NMR experiments for natural products chemistry and metabolomics applications, for which 35 μL is an optimal sample volume. The outstanding 13C sensitivity of this probe allowed us to directly determine the 13C connectivity on 1.1 mg of natural abundance histidine using an INADEQUATE experiment. We demonstrated the utility of this probe for 13C-based metabolomics using a synthetic mixture of common natural abundance metabolites whose concentrations ranged from 1 to 5 mM (40-200 nmol).

  5. Quantitative identification of metastable magnesium carbonate minerals by solid-state 13C NMR spectroscopy.

    PubMed

    Moore, Jeremy K; Surface, J Andrew; Brenner, Allison; Wang, Louis S; Skemer, Philip; Conradi, Mark S; Hayes, Sophia E

    2015-01-01

    In the conversion of CO2 to mineral carbonates for the permanent geosequestration of CO2, there are multiple magnesium carbonate phases that are potential reaction products. Solid-state (13)C NMR is demonstrated as an effective tool for distinguishing magnesium carbonate phases and quantitatively characterizing magnesium carbonate mixtures. Several of these mineral phases include magnesite, hydromagnesite, dypingite, and nesquehonite, which differ in composition by the number of waters of hydration or the number of crystallographic hydroxyl groups. These carbonates often form in mixtures with nearly overlapping (13)C NMR resonances which makes their identification and analysis difficult. In this study, these phases have been investigated with solid-state (13)C NMR spectroscopy, including both static and magic-angle spinning (MAS) experiments. Static spectra yield chemical shift anisotropy (CSA) lineshapes that are indicative of the site-symmetry variations of the carbon environments. MAS spectra yield isotropic chemical shifts for each crystallographically inequivalent carbon and spin-lattice relaxation times, T1, yield characteristic information that assist in species discrimination. These detailed parameters, and the combination of static and MAS analyses, can aid investigations of mixed carbonates by (13)C NMR.

  6. Characterizing biomass fast pyrolysis oils by 13C-NMR and chemometric analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several biomass fast pyrolysis oils were characterized by 13C and DEPT NMR analysis to determine chemical functional group compositions as related to their energy content. Pyrolysis oils were produced from a variety of feedstocks including energy crops, woods, animal wastes and oil seed presscakes,...

  7. Following Glycolysis Using 13C NMR: An Experiment Adaptable to Different Undergraduate Levels

    NASA Astrophysics Data System (ADS)

    Mega, T. L.; Carlson, C. B.; Cleary, D. A.

    1997-12-01

    This paper describes a laboratory exercise where the glycolysis of [1-13C] glucose under anaerobic conditions was followed using 13C NMR spectroscopy. The exercise is described in terms of its suitability for a variety of different undergraduate levels, although the emphasis in this paper is on its use in a n advanced chemistry laboratory course. The kinetics of the loss of glucose and the production of ethanol were investigated and found not to fit simple first or second order kinetics. In addition, the relative reaction rates of the two anomeric forms of glucose were analyzed, and it was determined that the a anomeric form reacted faster than the β anomeric form. Using proton-coupled 13C NMR, some of the metabolites were identified including ethanol (major) and glycerol (minor). Reaction and spectroscopic details are included.

  8. Quantitative Analysis of Metabolic Mixtures by 2D 13C-Constant-Time TOCSY NMR Spectroscopy

    PubMed Central

    Bingol, Kerem; Zhang, Fengli; Bruschweiler-Li, Lei; Brüschweiler, Rafael

    2013-01-01

    An increasing number of organisms can be fully 13C-labeled, which has the advantage that their metabolomes can be studied by high-resolution 2D NMR 13C–13C constant-time (CT) TOCSY experiments. Individual metabolites can be identified via database searching or, in the case of novel compounds, through the reconstruction of their backbone-carbon topology. Determination of quantitative metabolite concentrations is another key task. Because significant peak overlaps in 1D NMR spectra prevents straightforward quantification through 1D peak integrals, we demonstrate here the direct use of 13C–13C CT-TOCSY spectra for metabolite quantification. This is accomplished through the quantum-mechanical treatment of the TOCSY magnetization transfer at short and long mixing times or by the use of analytical approximations, which are solely based on the knowledge of the carbon-backbone topologies. The methods are demonstrated for carbohydrate and amino-acid mixtures. PMID:23773204

  9. Collaborative Student Laboratory Exercise Using FT-IR Spectroscopy for the Kinetics Study of a Biotin Analogue

    ERIC Educational Resources Information Center

    Leong, Jhaque; Ackroyd, Nathan C.; Ho, Karen

    2014-01-01

    The synthesis of N-methoxycarbonyl-2-imidazolidone, an analogue of biotin, was conducted by organic chemistry students and confirmed using FT-IR and H NMR. Spectroscopy students used FT-IR to measure the rate of hydrolysis of the product and determined the rate constant for the reaction using the integrated rate law. From the magnitude of the rate…

  10. 13C CP MAS NMR and GIAO-CHF calculations of coumarins.

    PubMed

    Zolek, Teresa; Paradowska, Katarzyna; Wawer, Iwona

    2003-01-01

    13C cross-polarization magic-angle spinning NMR spectra were recorded for a series of solid coumarins. Ab initio calculations of shielding constants were performed with the use of GIAO-CHF method. The combined CPMAS NMR and theoretical approach was successful in characterizing solid-state conformations of coumarins; a relationship sigma (ppm) = -1.032 xdelta + 205.28 (R(2) = 0.9845) can be used to obtain structural information for coumarins, for which solid-state NMR or crystal structure data are not available.

  11. High-resolution proton NMR studies of intracellular metabolites in yeast using 13C decoupling

    NASA Astrophysics Data System (ADS)

    Sillerud, Laurel O.; Alger, Jeffry R.; Shulman, Robert G.

    The resolution and specificity of 1H NMR in studies of yeast cellular metabolism were increased by feeding a 13C-labeled substrate and observing 1H difference spectra in the presence and absence of 13C decoupling fields. [2- 13C]Acetate was utilized as a respiratory substrate in an aerobic suspension of Saccharomyces cerevisiae. The broad cellular background proton resonances are removed by the technique, leaving only signals from the protons of the substrate, or its metabolites, that are coupled to 13C. Spectra of the yeast suspension after acetate feeding show the disappearance of label from the acetate pool and the subsequent appearance of 13C in glutamate C 3 and C 4 and in aspartate C 3. These results are in accord with the known fluxes of metabolites. Selective single-frequency 13C decoupling was used to provide assignments for the difference signals. The limitations on single-frequency decoupling coming from finite decoupling fields are investigated. The technique shows a potential for application in a wide variety of systems where the resolution of the 13C spectrum may be combined with the sensitivity for proton detection to observe metabolites that have been previously unobservable.

  12. 15N and13C NMR investigation of hydroxylamine-derivatized humic substances

    USGS Publications Warehouse

    Thorn, K.A.; Arterburn, J.B.; Mikita, M.A.

    1992-01-01

    Five fulvic and humic acid samples of diverse origins were derivatized with 15N-labeled hydroxylamine and analyzed by liquid-phase 15N NMR spectrometry. The 15N NMR spectra indicated that hydroxylamine reacted similarly with all samples and could discriminate among carbonyl functional groups. Oximes were the major derivatives; resonances attributable to hydroxamic acids, the reaction products of hydroxylamine with esters, and resonances attributable to the tautomeric equilibrium position between the nitrosophenol and monoxime derivatives of quinones, the first direct spectroscopic evidence for quinones, also were evident. The 15N NMR spectra also suggested the presence of nitriles, oxazoles, oxazolines, isocyanides, amides, and lactams, which may all be explained in terms of Beckmann reactions of the initial oxime derivatives. INEPT and ACOUSTIC 15N NMR spectra provided complementary information on the derivatized samples. 13C NMR spectra of derivatized samples indicated that the ketone/quinone functionality is incompletely derivatized with hydroxylamine. ?? 1991 American Chemical Society.

  13. FT-IR analysis of phosphorylated protein

    NASA Astrophysics Data System (ADS)

    Ishii, Katsunori; Yoshihashi, Sachiko S.; Chihara, Kunihiro; Awazu, Kunio

    2004-09-01

    Phosphorylation and dephosphorylation, which are the most remarkable posttranslational modifications, are considered to be important chemical reactions that control the activation of proteins. We examine the phosphorylation analysis method by measuring the infrared absorption peak of phosphate group that observed at about 1070cm-1 (9.4μm) with Fourier Transform Infrared Spectrometer (FT-IR). This study indicates that it is possible to identify a phosphorylation by measuring the infrared absorption peak of phosphate group observed at about 1070 cm-1 with FT-IR method. As long as target peptides have the same amino acid sequence, it is possible to identify the phosphorylated sites (threonine, serine and tyrosine).

  14. Methylation patterns of aquatic humic substances determined by 13C NMR spectroscopy

    USGS Publications Warehouse

    Thorn, K.A.; Steelink, C.; Wershaw, R. L.

    1987-01-01

    13C NMR spectroscopy is used to examine the hydroxyl group functionality of a series of humic and fulvic acids from different aquatic environments. Samples first are methylated with 13C-labeled diazomethane. The NMR spectra of the diazomethylated samples allow one to distinguish between methyl esters of carboxylic acids, methyl ethers of phenolic hydroxyls, and methyl ethers of phenolic hydroxyls adjacent to two substituents. Samples are then permethylated with 13C-labeled methyl iodide/NaH. 13C NMR spectra of permethylated samples show that a significant fraction of the hydroxyl groups is not methylated with diazomethane alone. In these spectra methyl ethers of carbohydrate and aliphatic hydroxyls overlap with methyl ethers of phenolic hydroxyls. Side reactions of the methyltion procedure including carbon methylation in the CH3I/NaH procedure, are also examined. Humic and fulvic acids from bog, swamp, groundwater, and lake waters showssome differences in their distribution of hydroxyl groups, mainly in the concentrations of phenolic hydroxyls, which may be attributed to their different biogeochemical origins. ?? 1987.

  15. Identification of natural metabolites in mixture: a pattern recognition strategy based on (13)C NMR.

    PubMed

    Hubert, Jane; Nuzillard, Jean-Marc; Purson, Sylvain; Hamzaoui, Mahmoud; Borie, Nicolas; Reynaud, Romain; Renault, Jean-Hugues

    2014-03-18

    Because of their highly complex metabolite profile, the chemical characterization of bioactive natural extracts usually requires time-consuming multistep purification procedures to achieve the structural elucidation of pure individual metabolites. The aim of the present work was to develop a dereplication strategy for the identification of natural metabolites directly within mixtures. Exploiting the polarity range of metabolites, the principle was to rapidly fractionate a multigram quantity of a crude extract by centrifugal partition extraction (CPE). The obtained fractions of simplified chemical composition were subsequently analyzed by (13)C NMR. After automatic collection and alignment of (13)C signals across spectra, hierarchical clustering analysis (HCA) was performed for pattern recognition. As a result, strong correlations between (13)C signals of a single structure within the mixtures of the fraction series were visualized as chemical shift clusters. Each cluster was finally assigned to a molecular structure with the help of a locally built (13)C NMR chemical shift database. The proof of principle of this strategy was achieved on a simple model mixture of commercially available plant secondary metabolites and then applied to a bark extract of the African tree Anogeissus leiocarpus Guill. & Perr. (Combretaceae). Starting from 5 g of this genuine extract, the fraction series was generated by CPE in only 95 min. (13)C NMR analyses of all fractions followed by pattern recognition of (13)C chemical shifts resulted in the unambiguous identification of seven major compounds, namely, sericoside, trachelosperogenin E, ellagic acid, an epimer mixture of (+)-gallocatechin and (-)-epigallocatechin, 3,3'-di-O-methylellagic acid 4'-O-xylopyranoside, and 3,4,3'-tri-O-methylflavellagic acid 4'-O-glucopyranoside. PMID:24555703

  16. Double cross polarization /sup 13/C-NMR experiment in solid fossil fuel structure analysis

    SciTech Connect

    Hagaman, E.W.; Woody, M.C.

    1988-01-01

    The Double Cross Polarization /sup 13/C-MAS/NMR experiment has been used to derive a new operational classification of solid fossil fuels based on chemical reactivity. The method requires labeling reactive sites in the organic matrix with a magnetically active isotope not present in the precursor material, and using the local, isolated dipole-dipole interaction between this nucleus and nearby /sup 13/C nuclei to detect via cross polarization the carbon centers in the vicinity of the label. The technique is a marriage of chemistry and spectroscopy and the information content of the DCP spectra is defined by both partners. /sup 1/H-/sup 13/C-/sup 31/P DCP/MAS /sup 13/C-NMR spectroscopy has been used to statistically describe phenolic ortho-substitution patterns of coals via their aryl phosphinate or phosphate derivatives. In these applications of DCP NMR the new, detailed structure and/or reactivity information is realized by detection of carbon resonances one or more bonds removed from the reaction center, but in a volume element of intramolecular dimensions. To the extent that intermolecular contributions to the spectrum are detected, and not recognized as such, the structure/reactivity correlation is weakened. Direct substitution of phosphorus on the aromatic rings in the organic matrix of the coal is not readily accomplished. This environment potentially can be labeled with fluorine in a selective fashion using newly developed reagents. The possibility of determining the changes in average ring substitution patterns as a function of chemical treatment or coal diagenesis emerges. Recent developments in the field of DCP /sup 13/C NMR are presented.

  17. Reversible dimer formation and stability of the anti-tumour single-chain Fv antibody MFE-23 by neutron scattering, analytical ultracentrifugation, and NMR and FT-IR spectroscopy.

    PubMed

    Lee, Yie Chia; Boehm, Mark K; Chester, Kerry A; Begent, Richard H J; Perkins, Stephen J

    2002-06-28

    MFE-23 is a single chain Fv (scFv) antibody molecule used to target colorectal cancer through its high affinity for the tumour marker carcinoembryonic antigen (CEA). ScFv molecules are formed from peptide-linked antibody V(H) and V(L) domains, and many of these form dimers. Our recent crystal structure for MFE-23 showed that this formed an unusual symmetric back-to-back association of two monomers that is consistent with a domain-swapped diabody structure. Neutron scattering and modelling fits showed that MFE-23 existed as compact V(H)-V(L)-linked monomers at therapeutically relevant concentrations below 1 mg/ml. Size-exclusion gel chromatography showed that the monomeric and dimeric forms of MFE-23 could be separated, and that the proportions of these two forms depended on the starting MFE-23 concentration. Sedimentation equilibrium experiments by analytical ultracentrifugation at nine concentrations of MFE-23 indicated a reversible monomer-dimer self-association equilibrium with an association constant of 1.9x10(3)-2.2x10(3) M(-1). Sedimentation velocity experiments using the time derivative g(s(*)) method showed that MFE-23-His has a concentration-dependent weight average sedimentation coefficient that increased from 1.8 S for the monomer to about 3-6 S for the dimer. Both values agreed with those calculated from the MFE-23 crystal structure. In relation to the thermal stability of MFE-23, denaturation experiments by (1)H NMR and FT-IR spectroscopy showed that the molecule is stable up to 47 degrees C, after which denaturation was irreversible. MFE-23 dimerisation is discussed in terms of a new model for diabody structures, in which the V(H) and V(L) domains in the monomer are able to dissociate and reassociate to form a dimer, or diabody, but in which symmetric back-to-back contacts between the two monomers are formed. This dimerisation in solution is attributed to the complementary nature of the C-terminal surface of the MFE-23 monomer. Crystal structures for

  18. Determination of fructose metabolic pathways in normal and fructose-intolerant children: A sup 13 C NMR study using (U- sup 13 C)fructose

    SciTech Connect

    Gopher, A.; Lapidot, A. ); Vaisman, N. ); Mandel, H. )

    1990-07-01

    An inborn deficiency in the ability of aldolase B to split fructose 1-phosphate is found in humans with hereditary fructose intolerance (HFI). A stable isotope procedure to elucidate the mechanism of conversion of fructose to glucose in normal children and in HFI children has been developed. A constant infusion of D-(U-{sup 13}C)fructose was given nasogastrically to control and to HFI children. Hepatic fructose conversion to glucose was estimated by examination of {sup 13}C NMR spectra of plasma glucose. Significantly lower values ({approx}3-fold) for fructose conversion to glucose were obtained for the HFI patients as compared to the controls. A quantitative determination of the metabolic pathways of fructose conversion to glucose was derived from {sup 13}C NMR measurement of plasma ({sup 13}C)glucose isotopomer populations. The finding of isotopomer populations of three adjacent {sup 13}C atoms at glucose C-4 ({sup 13}C{sub 3}-{sup 13}C{sub 4}-{sup 13}C{sub 5}) suggests that there is a direct pathway from fructose, by-passing fructose-1-phosphate aldolase, to fructose 1,6-bisphosphate. The metabolism of fructose by fructose-1-phosphate aldolase activity accounts for only {approx}50% of the total amount of hepatic fructose conversion to glucose. In view of the marked decline by 67% in synthesis of glucose from fructose in HFI subjects found in this study, the extent of ({sup 13}C)glucose formation from a trace amount of (U-{sup 13}C)fructose infused into the patient can be used as a safe and noninvasive diagnostic test for inherent faulty fructose metabolism.

  19. (1) H and (13) C NMR data on natural and synthetic capsaicinoids.

    PubMed

    Gómez-Calvario, Víctor; Garduño-Ramírez, María Luisa; León-Rivera, Ismael; Rios, María Yolanda

    2016-04-01

    Capsaicinoids are the compounds responsible for the pungency of chili peppers. These substances have attracted the attention of many research groups in recent decades because of their antinociceptive, analgesic, anti-inflammatory, and anti-obesity properties, among others. There are nearly 160 capsaicinoids reported in the literature. Approximately 25 of them are natural products, while the rest are synthetic or semi-synthetic products. A large amount of NMR data for the capsaicinoids is dispersed throughout literature. Therefore, there is a need to organize all this NMR data in a systematic and orderly way. This review summarizes the (1) H and (13) C NMR data on 159 natural and synthetic capsaicinoids, with a brief discussion of some typical and relevant aspects of these NMR data. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26626418

  20. (1) H and (13) C NMR data on natural and synthetic capsaicinoids.

    PubMed

    Gómez-Calvario, Víctor; Garduño-Ramírez, María Luisa; León-Rivera, Ismael; Rios, María Yolanda

    2016-04-01

    Capsaicinoids are the compounds responsible for the pungency of chili peppers. These substances have attracted the attention of many research groups in recent decades because of their antinociceptive, analgesic, anti-inflammatory, and anti-obesity properties, among others. There are nearly 160 capsaicinoids reported in the literature. Approximately 25 of them are natural products, while the rest are synthetic or semi-synthetic products. A large amount of NMR data for the capsaicinoids is dispersed throughout literature. Therefore, there is a need to organize all this NMR data in a systematic and orderly way. This review summarizes the (1) H and (13) C NMR data on 159 natural and synthetic capsaicinoids, with a brief discussion of some typical and relevant aspects of these NMR data. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Phenyl galactopyranosides - 13C CPMAS NMR and conformational analysis using genetic algorithm

    NASA Astrophysics Data System (ADS)

    Wałejko, Piotr; Paradowska, Katarzyna; Bukowicki, Jarosław; Witkowski, Stanisław; Wawer, Iwona

    2015-08-01

    Structural analyses of four compounds (phenyl 2,3,4,6-tetra-O-acetyl-β-D-galactopyranoside (1), phenyl β-D-galactopyranoside (2), phenyl 2,3,4,6-tetra-O-acetyl-α-D-galactopyranoside (3) and phenyl α-D-galactopyranoside (4)) have been performed using solid-state 13C MAS NMR spectroscopy and theoretical methods. Conformational analysis involved grid search and genetic algorithm (GAAGS). Low-energy conformers found by GAAGS were further optimized by DFT and chemical shifts were calculated using GIAO/DFT approach. 13C CPMAS NMR chemical shift of carbon C2 is indicative of the glycoside torsional angle. Separated or merged resonances of C2 and C6 suggest free rotation of phenyl ring in the solid phase.

  2. Complete (1)H and (13)C signal assignment of prenol-10 with 3D NMR spectroscopy.

    PubMed

    Misiak, Maria; Koźmiński, Wiktor; Kwasiborska, Maria; Wójcik, Jacek; Ciepichal, Ewa; Swiezewska, Ewa

    2009-10-01

    The complete assignment of (1)H and (13)C chemical shifts of natural abundance prenol-10 is reported for the first time. It was achieved using 3D NMR experiments, which were based on random sampling of the evolution time space followed by multidimensional Fourier transform. This approach makes it possible to acquire 3D NMR spectra in a reasonable time and preserves high resolution in indirectly detected dimensions. It is shown that the interpretation of 3D COSY-HMBC and 3D TOCSY-HSQC spectra is crucial in the structural analysis of prenol-10.

  3. Using Neural Networks for 13C NMR Chemical Shift Prediction-Comparison with Traditional Methods

    NASA Astrophysics Data System (ADS)

    Meiler, Jens; Maier, Walter; Will, Martin; Meusinger, Reinhard

    2002-08-01

    Interpretation of 13C chemical shifts is essential for structure elucidation of organic molecules by NMR. In this article, we present an improved neural network approach and compare its performance to that of commonly used approaches. Specifically, our recently proposed neural network ( J. Chem. Inf. Comput. Sci. 2000, 40, 1169-1176) is improved by introducing an extended hybrid numerical description of the carbon atom environment, resulting in a standard deviation (std. dev.) of 2.4 ppm for an independent test data set of ˜42,500 carbons. Thus, this neural network allows fast and accurate 13C NMR chemical shift prediction without the necessity of access to molecule or fragment databases. For an unbiased test dataset containing 100 organic structures the accuracy of the improved neural network was compared to that of a prediction method based on the HOSE code ( hierarchically ordered spherical description of environment) using S PECI NFO. The results show the neural network predictions to be of quality (std. dev.=2.7 ppm) comparable to that of the HOSE code prediction (std. dev.=2.6 ppm). Further we compare the neural network predictions to those of a wide variety of other 13C chemical shift prediction tools including incremental methods (C HEMD RAW, S PECT OOL), quantum chemical calculation (G AUSSIAN, C OSMOS), and HOSE code fragment-based prediction (S PECI NFO, ACD/CNMR, P REDICTI T NMR) for the 47 13C-NMR shifts of Taxol, a natural product including many structural features of organic substances. The smallest standard deviations were achieved here with the neural network (1.3 ppm) and S PECI NFO (1.0 ppm).

  4. Complete 1H and 13C NMR assignments of two phytosterols from roots of Piper nigrum.

    PubMed

    Wei, Kun; Li, Wei; Koike, Kazuo; Pei, Yuping; Chen, Yingjie; Nikaido, Tamotsu

    2004-03-01

    Using modern NMR techniques, including DQF-COSY, NOESY, HETCOR and HMBC, the full assignments of all 1H and 13C chemical shifts were made for stigmastane-3,6-dione and stigmast-4-ene-3,6-dione, isolated from the roots of Piper nigrum (Piperaceae). Their stereochemistry was resolved by a combination of 2D NOESY data and analysis of coupling constants. The two compounds were isolated from the genus Piper for the first time.

  5. Calculation of the 13C NMR shieldings of the C0 2 complexes of aluminosilicates

    NASA Astrophysics Data System (ADS)

    Tossell, J. A.

    1995-04-01

    13C NMR shieldings have been calculated using the random-phase-approximation, localized-orbital local-origins version of ab initio coupled Hartree-Fuck perturbation theory for CO 2 and and for several complexes formed by the reaction of CO 2 with molecular models for aluminosilicate glasses, H 3TOT'H3 3-n, T,T' = Si,Al. Two isomeric forms of the CO 2-aluminosilicate complexes have been considered: (1) "CO 2-like" complexes, in which the CO 2 group is bound through carbon to a bridging oxygen and (2) "CO 3-like" complexes, in which two oxygens of a central CO 3 group form bridging bonds to the two TH 3 groups. The CO 2-like isomer of CO 2-H 3SiOSiH 3 is quite weakly bonded and its 13C isotropic NMR shielding is almost identical to that in free CO 2. As Si is progressively replaced by Al in the - H terminated aluminosilicate model, the CO 2-like isomers show increasing distortion from the free CO 2 geometry and their 13C NMR shieldings decrease uniformly. The calculated 13C shielding value for H 3AlO(CO 2)AlH 3-2 is only about 6 ppm larger than that calculated for point charge stabilized CO 3-2. However, for a geometry of H 3SiO(CO 2) AlH 3-1, in which the bridging oxygen to C bond length has been artificially increased to that found in the - OH terminated cluster (OH) 3SiO(CO 2)Al(OH) 3-1, the calculated 13C shielding is almost identical to that for free CO 2. The CO 3-like isomers of the CO 2-aluminosili-cate complexes show carbonate like geometries and 13C NMR shieldings about 4-9 ppm larger than those of carbonate for all T,T' pairs. For the Si,Si tetrahedral atom pair the CO 2-like isomer is more stable energetically, while for the Si,Al and Al,Al cases the CO 3-like isomer is more stable. Addition of Na + ions to the CO 3-2 or H 3AlO(CO 2)AlH 3-2 complexes reduces the 13C NMR shieldings by about 10 ppm. Complexation with either Na + or CO 2 also reduces the 29Si NMR shieldings of the aluminosilicate models, while the changes in 27Al shielding with Na + or CO 2

  6. Metabolic pathways for ketone body production. /sup 13/C NMR spectroscopy of rat liver in vivo using /sup 13/C-multilabeled fatty acids

    SciTech Connect

    Pahl-Wostl, C.; Seelig, J.

    1986-11-04

    The hormonal regulation of ketogenesis in the liver of living rat has been studied noninvasively with /sup 13/C nuclear magnetic resonance. The spatial selection for the liver was better than 90%, with extrahepatic adipose tissue contribution only a very small amount of signal. The metabolic activities of the liver were investigated by infusion of /sup 13/C-labeled butyrate in the jugular vein of the anesthetized rat. The rate of butyrate infusion was chosen to be close to the maximum oxidative capacity of the rat liver, and the /sup 13/C signal intensities were enhanced by using doubly labeled (1,3-/sup 13/C)butyrate as a substrate. Different /sup 13/C NMR spectra and hence different metabolites were observed depending on the hormonal state of the animal. The /sup 13/C NMR studies demonstrate that even when rate of acetyl-CoA production are high, the disposal of this compound is not identical in fasted and diabetic animals. This supports previous suggestions that the redox state of the mitochondrion represents the most important factor in regulation. For a given metabolic state of the animal, different signal intensities were obtained depending on whether butyrate was labeled at C-1, C-3, or C-1,3. From the ratios of incorporation of /sup 13/C label into the carbons of 3-hydroxybutyrate, it could be estimated that a large fraction of butyrate evaded ..beta..-oxidation to acetyl-CoA but was converted directly to acetoacetyl-CoA. /sup 13/C-labeled glucose could be detected in vivo in the liver of diabetic rats.

  7. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    PubMed

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom. PMID:26670708

  8. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    PubMed

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom.

  9. Improved Carbohydrate Structure Generalization Scheme for (1)H and (13)C NMR Simulations.

    PubMed

    Kapaev, Roman R; Toukach, Philip V

    2015-07-21

    The improved Carbohydrate Structure Generalization Scheme has been developed for the simulation of (13)C and (1)H NMR spectra of oligo- and polysaccharides and their derivatives, including those containing noncarbohydrate constituents found in natural glycans. Besides adding the (1)H NMR calculations, we improved the accuracy and performance of prediction and optimized the mathematical model of the precision estimation. This new approach outperformed other methods of chemical shift simulation, including database-driven, neural net-based, and purely empirical methods and quantum-mechanical calculations at high theory levels. It can process structures with rarely occurring and noncarbohydrate constituents unsupported by the other methods. The algorithm is transparent to users and allows tracking used reference NMR data to original publications. It was implemented in the Glycan-Optimized Dual Empirical Spectrum Simulation (GODESS) web service, which is freely available at the platform of the Carbohydrate Structure Database (CSDB) project ( http://csdb.glycoscience.ru). PMID:26087011

  10. Solid state 13C NMR investigation of impact of annealing in lyophilized glasses.

    PubMed

    Luthra, Suman A; Pikal, Michael J; Utz, Marcel

    2008-10-01

    The purpose of this study was to investigate the impact of annealing on molecular mobility in lyophilized glasses, composed of a saccharide excipient and a small concentration of aspartame as a model "drug." Changes in molecular dynamics during annealing were monitored through carbon ((13)C) T(1) and T(1 rho) nuclear magnetic resonance relaxation times of the aspartame and the saccharides. Two different saccharides were studied, sucrose and trehalose. The local mobility of the aspartame guest was found to correlate closely with the overall structural relaxation monitored through calorimetric methods in the aspartame: sucrose formulation. In general terms, annealing leads to longer NMR relaxation times, indicating a slowing of the local dynamics. By contrast, annealing had only a minimal effect on the NMR relaxation times in aspartame: trehalose. Specificity of solid state NMR in detecting molecular mobility in guest and host molecules showed that sucrose provided a homogenous matrix for the guest drug as compared to the trehalose.

  11. Neuroprotective effects of caffeine in MPTP model of Parkinson's disease: A (13)C NMR study.

    PubMed

    Bagga, Puneet; Chugani, Anup N; Patel, Anant B

    2016-01-01

    Parkinson's disease (PD) is a neurodegenerative disorder characterized by degeneration of nigrostriatal dopaminergic neurons with an accompanying neuroinflammation leading to loss of dopamine in the basal ganglia. Caffeine, a well-known A2A receptor antagonist is reported to slow down the neuroinflammation caused by activated microglia and reduce the extracellular glutamate in the brain. In this study, we have evaluated the neuroprotective effect of caffeine in the MPTP model of PD by monitoring the region specific cerebral energy metabolism. Adult C57BL6 mice were treated with caffeine (30 mg/kg, i.p.) 30 min prior to MPTP (25 mg/kg, i.p.) administration for 8 days. The paw grip strength of mice was assessed in order to evaluate the motor function after various treatments. For metabolic studies, mice were infused with [1,6-(13)C2]glucose, and (13)C labeling of amino acids was monitored using ex vivo(1)H-[(13)C]-NMR spectroscopy. The paw grip strength was found to be reduced following the MPTP treatment. The caffeine pretreatment showed significant protection against the reduction of paw grip strength in MPTP treated mice. The levels of GABA and myo-inositol were found to be elevated in the striatum of MPTP treated mice. The (13)C labeling of GluC4, GABAC2 and GlnC4 from [1,6-(13)C2]glucose was decreased in the cerebral cortex, striatum, olfactory bulb, thalamus and cerebellum suggesting impaired glutamatergic and GABAergic neuronal activity and neurotransmission of the MPTP treated mice. Most interestingly, the pretreatment of caffeine maintained the (13)C labeling of amino acids to the control values in cortical, olfactory bulb and cerebellum regions while it partially retained in striatal and thalamic regions in MPTP treated mice. The pretreatment of caffeine provides a partial neuro-protection against severe striatal degeneration in the MPTP model of PD.

  12. Advances in handheld FT-IR instrumentation

    NASA Astrophysics Data System (ADS)

    Arnó, Josep; Cardillo, Len; Judge, Kevin; Frayer, Maxim; Frunzi, Michael; Hetherington, Paul; Levy, Dustin; Oberndorfer, Kyle; Perec, Walter; Sauer, Terry; Stein, John; Zuidema, Eric

    2012-06-01

    FT-IR spectroscopy is the technology of choice to identify solid and liquid phase unknown samples. The challenges of ConOps (Concepts of Operation) in emergency response and military field applications require a significant redesign of the stationary FT-IR bench-top instruments typically used in laboratories. Specifically, field portable units require high levels of resistance against mechanical shock and chemical attack, ease of use in restrictive gear, quick and easy interpretation of results, and reduced size. In the last 20 years, FT-IR instruments have been re-engineered to fit in small suitcases for field portable use and recently further miniaturized for handheld operation. This article introduces the advances resulting from a project designed to overcome the challenges associated with miniaturizing FT-IR instruments. The project team developed a disturbance-corrected permanently aligned cube corner interferometer for improved robustness and optimized opto-mechanical design to maximize optical throughput and signal-to-noise ratios. Thermal management and heat flow were thoroughly modeled and studied to isolate sensitive components from heat sources and provide the widest temperature operation range. Similarly, extensive research on mechanical designs and compensation techniques to protect against shock and vibration will be discussed. A user interface was carefully created for military and emergency response applications to provide actionable information in a visual, intuitive format. Similar to the HazMatID family of products, state-of-the-art algorithms were used to quickly identify the chemical composition of complex samples based on the spectral information. This article includes an overview of the design considerations, tests results, and performance validation of the mechanical ruggedness, spectral, and thermal performance.

  13. Combined experimental (FT-IR, UV-visible spectra, NMR) and theoretical studies on the molecular structure, vibrational spectra, HOMO, LUMO, MESP surfaces, reactivity descriptor and molecular docking of Phomarin

    NASA Astrophysics Data System (ADS)

    Kumar, Abhishek; Srivastava, Ambrish Kumar; Gangwar, Shashi; Misra, Neeraj; Mondal, Avijit; Brahmachari, Goutam

    2015-09-01

    Phomarin is an important natural product belonging to anthraquinone series of compounds. The equilibrium geometry of phomarin has been determined and analyzed at DFT method employing B3LYP/6-311++G(d,p) level of computation. The reactivity of molecule using various descriptors such as Fukui functions, local softness, electrophilicity, electronegativity, Hardness, HOMO-LUMO gap are calculated and discussed. The infrared and UV-vis spectra of phomarin are calculated and compared with the experimentally observed ones. Moreover, 1H and 13C NMR spectra have been calculated by using the gauge independent atomic orbital method. We also notice that phomarin shows remarkable biological activities against malaria parasite. The study suggests further investigation on phomarin for their pharmacological importance.

  14. Accurate measurements of {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled proteins using multi-dimensional four-oscillating field solid-state NMR spectroscopy

    SciTech Connect

    Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Nielsen, Niels Chr.; Khaneja, Navin

    2014-09-21

    Application of sets of {sup 13}C-{sup 13}C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl ({sup 13}C′) and aliphatic ({sup 13}C{sub aliphatic}) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly {sup 13}C,{sup 15}N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of {sup 13}C′-{sup 13}C{sub aliphatic} distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform {sup 13}C,{sup 15}N-labeling on the FGAIL fragment.

  15. Analysis of Hydroperoxides in Solid Polyethylene by MAS (13)C NMR and EPR

    SciTech Connect

    ASSINK,ROGER A.; CELINA,MATHIAS C.; DUNBAR,TIMOTHY D.; ALAM,TODD M.; CLOUGH,ROGER LEE; GILLEN,KENNETH T.

    1999-11-19

    {sup 13}C-enriched polyethylene was subjected to {gamma}-irradiation in the presence of air at 25 and 80 C for total doses ranging from 71 to 355 kGy. Significant quantities of hydroperoxides were detected in the 25 C irradiated sample by {sup 13}C magic angle spinning NMR spectroscopy. This method of detection was performed on the solid polymer and required no chemical derivatization or addition of solvent. The chemical stability and subsequent products of the hydroperoxide species were studied by annealing the irradiated samples in air at temperatures ranging from 22 to 110 C. A time-temperature superposition analysis provided an activation energy of 108 kJ/mol for the hydroperoxide decomposition process. The primary products of hydroperoxide decomposition were ketones and secondary alcohols with lesser amounts of acids and esters. EPR measurements suggest that the reactive hydroperoxide species reside in the amorphous phase of polyethylene, consistent with degradation occurring in the amorphous phase.

  16. NMR analyses of the cold cataract. III. /sup 13/C acrylamide studies

    SciTech Connect

    Lerman, S.; Megaw, J.M.; Moran, M.N.

    1985-10-01

    /sup 13/C-enriched acrylamide was employed to further delineate the action of this compound in preventing the cold cataract phenomenon when it is incorporated (in vitro) into young human and rabbit lenses. The extent of acrylamide incorporation, in the dark and with concurrent UV exposure, was monitored by /sup 13/C NMR spectroscopy. These studies provide further evidence that UV exposure causes permanent acrylamide photobinding within the lens. In such lenses, the gamma crystallin fraction of the soluble lens proteins is affected to the greatest extent. It appears to become aggregated and/or combined with the alpha and beta fractions resulting in an apparent loss of most of the gamma monomers. There is also an age-related effect with respect to the amount of acrylamide that can be incorporated into the lens. The decrease in acrylamide incorporation with age directly parallels the age-related decline in gamma crystallin levels.

  17. Direct measurement of brain glucose concentrations in humans by sup 13 C NMR spectroscopy

    SciTech Connect

    Gruetter, R.; Novotny, E.J.; Boulware, S.D.; Rothman, D.L.; Mason, G.F.; Shulman, G.I.; Shulan, R.G.; Tamborlane, W.V. )

    1992-02-01

    Glucose is the main fuel for energy metabolism in the normal human brain. It is generally assumed that glucose transport into the brain is not rate-limiting for metabolism. Since brain glucose concentrations cannot be determined directly by radiotracer techniques, the authors used {sup 13}C NMR spectroscopy after infusing enriched D-(1-{sup 13}C)glucose to measure brain glucose concentrations at euglycemia and at hyperglycemia in six healthy children. Brain glucose concentrations averaged 1.0 {plus minus} 0.1 {mu}mol/ml at euglycemia and 1.8-2.7 {mu}mol/ml at hyperglycemia. Michaelis-Menten parameters of transport were calculated from the relationship between plasma and brain glucose concentrations. The brain glucose concentrations and transport constants are consistent with transport not being rate-limiting for resting brain metabolism at plasma levels >3 mM.

  18. 13C NMR spectroscopy of the insoluble carbon of carbonaceous chondrites.

    PubMed

    Cronin, J R; Pizzarello, S; Frye, J S

    1987-01-01

    13C NMR spectra have been obtained of the insoluble carbon residues resulting from HF-digestion of three carbonaceous chondrites, Orgueil (C1), Murchison (CM2), and Allende (CV3). Spectra obtained using the cross polarization magic-angle spinning technique show two major features attributable respectively to carbon in aliphatic/olefinic structures. The spectrum obtained from the Allende sample was weak, presumably as a consequence of its low hydrogen content. Single pulse excitation spectra, which do not depend on 1H-13C polarization transfer for signal enhancement were also obtained. These spectra, which may be more representative of the total carbon in the meteorite samples, indicate a greater content of carbon in aromatic/olefinic structures. These results suggest that extensive polycyclic aromatic sheets are important structural features of the insoluble carbon of all three meteorites. The Orgueil and Murchison materials contain additional hydrogenated aromatic/olefinic and aliphatic groups.

  19. Direct observation of glycogen synthesis in human muscle with sup 13 C NMR

    SciTech Connect

    Jue, T.; Rothman, D.L.; Shulman, G.I.; Tavitian, B.A.; DeFronzo, R.A.; Shulman, R.G. )

    1989-06-01

    On the basis of previous indirect measurements, skeletal muscle has been implicated as the major site of glucose uptake and it has been suggested that muscle glycogen formation is the dominant pathway. However, direct measurements of the rates of glycogen synthesis have not been possible by previous techniques. The authors have developed {sup 13}C NMR methods to measure directly the rate of human muscle glycogen formation from infused, isotopically labeled (1-{sup 13}C)glucose. They show that under conditions of imposed hyperglycemia and hyperinsulinemia, a majority of the infused glucose was converted to muscle glycogen in a normal man. This directly shows that muscle is the major site of glucose disposal under these conditions, and provides quantitation of the glucose flux to muscle glycogen.

  20. 13C NMR spectroscopy of the insoluble carbon of carbonaceous chondrites

    NASA Technical Reports Server (NTRS)

    Cronin, J. R.; Pizzarello, S.; Frye, J. S.

    1987-01-01

    13C NMR spectra have been obtained of the insoluble carbon residues resulting from HF-digestion of three carbonaceous chondrites, Orgueil (C1), Murchison (CM2), and Allende (CV3). Spectra obtained using the cross polarization magic-angle spinning technique show two major features attributable respectively to carbon in aliphatic/olefinic structures. The spectrum obtained from the Allende sample was weak, presumably as a consequence of its low hydrogen content. Single pulse excitation spectra, which do not depend on 1H-13C polarization transfer for signal enhancement were also obtained. These spectra, which may be more representative of the total carbon in the meteorite samples, indicate a greater content of carbon in aromatic/olefinic structures. These results suggest that extensive polycyclic aromatic sheets are important structural features of the insoluble carbon of all three meteorites. The Orgueil and Murchison materials contain additional hydrogenated aromatic/olefinic and aliphatic groups.

  1. Hyperpolarized 13C NMR lifetimes in the liquid-state: relating structures and T1 relaxation times

    NASA Astrophysics Data System (ADS)

    Parish, Christopher; Niedbalski, Peter; Hashami, Zohreh; Fidelino, Leila; Kovacs, Zoltan; Lumata, Lloyd

    Among the various attempts to solve the insensitivity problem in nuclear magnetic resonance (NMR), the physics-based technique dissolution dynamic nuclear polarization (DNP) is probably the most successful method of hyperpolarization or amplifying NMR signals. Using this technique, liquid-state NMR signal enhancements of several thousand-fold are expected for low-gamma nuclei such as carbon-13. The lifetimes of these hyperpolarized 13C NMR signals are directly related to their 13C spin-lattice relaxation times T1. Depending upon the 13C isotopic location, the lifetimes of hyperpolarized 13C compounds can range from a few seconds to minutes. In this study, we have investigated the hyperpolarized 13C NMR lifetimes of several 13C compounds with various chemical structures from glucose, acetate, citric acid, naphthalene to tetramethylallene and their deuterated analogs at 9.4 T and 25 deg C. Our results show that the 13C T1s of these compounds can range from a few seconds to more than 60 s at this field. Correlations between the chemical structures and T1 relaxation times will be discussed and corresponding implications of these results on 13C DNP experiments will be revealed. US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  2. Trans and surface membrane bound zervamicin IIB: 13C-MAOSS-NMR at high spinning speed.

    PubMed

    Raap, J; Hollander, J; Ovchinnikova, T V; Swischeva, N V; Skladnev, D; Kiihne, S

    2006-08-01

    Interactions between (15)N-labelled peptides or proteins and lipids can be investigated using membranes aligned on a thin polymer film, which is rolled into a cylinder and inserted into the MAS-NMR rotor. This can be spun at high speed, which is often useful at high field strengths. Unfortuantely, substrate films like commercially available polycarbonate or PEEK produce severe overlap with peptide and protein signals in (13)C-MAOSS NMR spectra. We show that a simple house hold foil support allows clear observation of the carbonyl, aromatic and C(alpha) signals of peptides and proteins as well as the ester carbonyl and choline signals of phosphocholine lipids. The utility of the new substrate is validated in applications to the membrane active peptide zervamicin IIB. The stability and macroscopic ordering of thin PC10 bilayers was compared with that of thicker POPC bilayers, both supported on the household foil. Sidebands in the (31)P-spectra showed a high degree of alignment of both the supported POPC and PC10 lipid molecules. Compared with POPC, the PC10 lipids are slightly more disordered, most likely due to the increased mobilities of the shorter lipid molecules. This mobility prevents PC10 from forming stable vesicles for MAS studies. The (13)C-peptide peaks were selectively detected in a (13)C-detected (1)H-spin diffusion experiment. Qualitative analysis of build-up curves obtained for different mixing times allowed the transmembrane peptide in PC10 to be distinguished from the surface bound topology in POPC. The (13)C-MAOSS results thus independently confirms previous findings from (15)N spectroscopy [Bechinger, B., Skladnev, D.A., Ogrel, A., Li, X., Rogozhkina, E.V., Ovchinnikova, T.V., O'Neil, J.D.J. and Raap, J. (2001) Biochemistry, 40, 9428-9437]. In summary, application of house hold foil opens the possibility of measuring high resolution (13)C-NMR spectra of peptides and proteins in well ordered membranes, which are required to determine the secondary

  3. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

    PubMed

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles) has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED) test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR. PMID:27022916

  4. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy.

    PubMed

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles) has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED) test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR.

  5. The Influence of Plant Litter on Soil Water Repellency: Insight from 13C NMR Spectroscopy

    PubMed Central

    Cesarano, Gaspare; Incerti, Guido; Bonanomi, Giuliano

    2016-01-01

    Soil water repellency (SWR, i.e. reduced affinity for water owing to the presence of organic hydrophobic coatings on soil particles) has relevant hydrological implications because low rates of infiltration enhance water runoff, and untargeted diffusion of fertilizers and pesticides. Previous studies investigated the occurrence of SWR in ecosystems with different vegetation cover but did not clarify its relationships with litter biochemical quality. Here, we investigated the capability of different plant litter types to induce SWR by using fresh and decomposed leaf materials from 12 species, to amend a model sandy soil over a year-long microcosm experiment. Water repellency, measured by the Molarity of an Ethanol Droplet (MED) test, was tested for the effects of litter species and age, and compared with litter quality assessed by 13C-CPMAS NMR in solid state and elemental chemical parameters. All litter types were highly water repellent, with MED values of 18% or higher. In contrast, when litter was incorporated into the soil, only undecomposed materials induced SWR, but with a large variability of onset and peak dynamics among litter types. Surprisingly, SWR induced by litter addition was unrelated to the aliphatic fraction of litter. In contrast, lignin-poor but labile C-rich litter, as defined by O-alkyl C and N-alkyl and methoxyl C of 13C-CPMAS NMR spectral regions, respectively, induced a stronger SWR. This study suggests that biochemical quality of plant litter is a major controlling factor of SWR and, by defining litter quality with 13C-CPMAS NMR, our results provide a significant novel contribution towards a full understanding of the relationships between plant litter biochemistry and SWR. PMID:27022916

  6. 13C solid-state NMR chemical shift anisotropy analysis of the anomeric carbon in carbohydrates.

    PubMed

    Chen, Ying-Ying; Luo, Shun-Yuan; Hung, Shang-Cheng; Chan, Sunney I; Tzou, Der-Lii M

    2005-03-21

    (13)C NMR solid-state structural analysis of the anomeric center in carbohydrates was performed on six monosaccharides: glucose (Glc), mannose (Man), galactose (Gal), galactosamine hydrochloride (GalN), glucosamine hydrochloride (GlcN), and N-acetyl-glucosamine (GlcNAc). In the 1D (13)C cross-polarization/magic-angle spinning (CP/MAS) spectrum, the anomeric center C-1 of these carbohydrates revealed two well resolved resonances shifted by 3-5ppm, which were readily assigned to the anomeric alpha and beta forms. From this experiment, we also extracted the (13)C chemical shift anisotropy (CSA) tensor elements of the two forms from their spinning sideband intensities, respectively. It was found out that the chemical shift tensor for the alpha anomer was more axially symmetrical than that of the beta form. A strong linear correlation was obtained when the ratio of the axial asymmetry of the (13)C chemical shift tensors of the two anomeric forms was plotted in a semilogarithmic plot against the relative population of the two anomers. Finally, we applied REDOR spectroscopy to discern whether or not there were any differences in the sugar ring conformation between the anomers. Identical two-bond distances of 2.57A (2.48A) were deduced for both the alpha and beta forms in GlcNAc (GlcN), suggesting that the two anomers have essentially identical sugar ring scaffolds in these sugars. In light of these REDOR distance measurements and the strong correlation observed between the ratio of the axial asymmetry parameters of the (13)C chemical shift tensors and the relative population between the two anomeric forms, we concluded that the anomeric effect arises principally from interaction of the electron charge clouds between the C-1-O-5 and the C-1-O-1 bonds in these monosaccharides.

  7. 1H and 13C NMR study on some substituted azolidine derivatives

    NASA Astrophysics Data System (ADS)

    Cerioni, Giovanni; Cristiani, Franco; Devillanova, Francesco A.; Diaz, Angelo; Verani, Gaetano

    The 1H and 13C NMR spectra carried out on R overlineN·CH 2·CH 2·X·C O (where for R = H, X = NH, NMe, NEt, CH 2, S, O; for R = Me, X = NMe, CH 2; for R = Et, X = NEt) are reported. The comparison of these results with those obtained for the thionic and selonic isologues shows that sulphur and selenium have a greater deshielding effect on the ring than oxygen. The resonance of the carbons not involved in the π system have been correlated with the σ charges calculated by the DEL RE method.

  8. 13C NMR spectral characterization of epimeric rotenone and some related tetrahydrobenzopyranofurobenzopyranones

    USGS Publications Warehouse

    Abidi, S.L.; Abidi, M.S.

    1983-01-01

    The 13C nuclear magnetic resonance (nmr) spectra of epimers of rotenone and four 12a-hydroxy-analogues were examined to determine the stereochemical effect of the B/C ring fusion involving the 6a- and 12a-carbon centers. Chemical shift differences between the epimeric carbon resonances of cis- and trans-6a,12a-compounds were notably larger than those of diastereoisomers derived from the same B/C ring junction stereochemistry. Results of the spectral analysis have been useful for the quantification of mixtures of epimers and for the measurement of rates of epimerization and oxygenation.

  9. The binding of metal ions and angiotensin converting enzyme (ACE) inhibitor by 13C NMR

    NASA Astrophysics Data System (ADS)

    Sakamoto, Yohko; Sakamoto, Yuko; Ishii, Tomoko; Ohmoto, Taichi

    1991-06-01

    Enalaprilat (MK-422, 1- [ N- [1 (S)-carboxy-3-phenylpropyl]- L-alanyl]- L-proline (1)) and Lisinopril (MK521, N- N- [ (s)-l-carboxy-3- phenylpropyl]- L-lysyl- L-proline, (2)) exhibit the capacity to act as a chelate, unidentate or bridge towards metal ions in aqueous solution, as determined by 13C NMR. By adding metal ions, in the series of Zn 2+, Ni 2+, Pb 2+, Pd 2+ and Cd 2+, the active site of the ACE inhibitor was well defined. MK-521 was more influenced by nuclei that were distant from the active site than MK-422.

  10. Enantiomeric differentiation of acyclic terpenes by 13C NMR spectroscopy using a chiral lanthanide shift reagent.

    PubMed

    Blanc, Marie-Cécile; Bradesi, Pascale; Casanova, Joseph

    2005-02-01

    The 13C NMR behaviour of ten acyclic terpene alcohols was examined in the presence of a chiral lanthanide shift reagent (CLSR). For each alcohol, we measured the lanthanide-induced shift (LIS) on the signals of the carbons and the splitting of some signals, which allowed the enantiomeric differentiation. As expected, the LIS decreased with the number of bonds between the binding function and the considered carbon. The enantiomeric splitting is observed for several signals in the spectrum of each compound. The influence of the hindrance of the binding function (primary, secondary or tertiary alcohol) and that of the stereochemistry of the double bonds is discussed.

  11. Compartmentalized Cerebral Metabolism of [1,6-13C]Glucose Determined by in vivo 13C NMR Spectroscopy at 14.1 T

    PubMed Central

    Duarte, João M. N.; Lanz, Bernard; Gruetter, Rolf

    2011-01-01

    Cerebral metabolism is compartmentalized between neurons and glia. Although glial glycolysis is thought to largely sustain the energetic requirements of neurotransmission while oxidative metabolism takes place mainly in neurons, this hypothesis is matter of debate. The compartmentalization of cerebral metabolic fluxes can be determined by 13C nuclear magnetic resonance (NMR) spectroscopy upon infusion of 13C-enriched compounds, especially glucose. Rats under light α-chloralose anesthesia were infused with [1,6-13C]glucose and 13C enrichment in the brain metabolites was measured by 13C NMR spectroscopy with high sensitivity and spectral resolution at 14.1 T. This allowed determining 13C enrichment curves of amino acid carbons with high reproducibility and to reliably estimate cerebral metabolic fluxes (mean error of 8%). We further found that TCA cycle intermediates are not required for flux determination in mathematical models of brain metabolism. Neuronal tricarboxylic acid cycle rate (VTCA) and neurotransmission rate (VNT) were 0.45 ± 0.01 and 0.11 ± 0.01 μmol/g/min, respectively. Glial VTCA was found to be 38 ± 3% of total cerebral oxidative metabolism, accounting for more than half of neuronal oxidative metabolism. Furthermore, glial anaplerotic pyruvate carboxylation rate (VPC) was 0.069 ± 0.004 μmol/g/min, i.e., 25 ± 1% of the glial TCA cycle rate. These results support a role of glial cells as active partners of neurons during synaptic transmission beyond glycolytic metabolism. PMID:21713114

  12. Spectroscopic (FT-IR, FT-Raman, NMR and UV-Visible) and quantum chemical studies of molecular geometry, Frontier molecular orbital, NLO, NBO and thermodynamic properties of salicylic acid.

    PubMed

    Suresh, S; Gunasekaran, S; Srinivasan, S

    2014-11-11

    The solid phase FT-IR and FT-Raman spectra of 2-hydroxybenzoic acid (salicylic acid) have been recorded in the region 4000-400 and 4000-100 cm(-1) respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method at 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimentally obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method is employed to predict its absorption energy and oscillator strength. The linear polarizability (α) and the first order hyper polarizability (β) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MEP) are also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

  13. Spectroscopic (FT-IR, FT-Raman, NMR and UV-Visible) and quantum chemical studies of molecular geometry, Frontier molecular orbital, NLO, NBO and thermodynamic properties of salicylic acid

    NASA Astrophysics Data System (ADS)

    Suresh, S.; Gunasekaran, S.; Srinivasan, S.

    2014-11-01

    The solid phase FT-IR and FT-Raman spectra of 2-hydroxybenzoic acid (salicylic acid) have been recorded in the region 4000-400 and 4000-100 cm-1 respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method at 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimentally obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method is employed to predict its absorption energy and oscillator strength. The linear polarizability (α) and the first order hyper polarizability (β) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MEP) are also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

  14. (13) C-TmDOTA as versatile thermometer compound for solid-state NMR of hydrated lipid bilayer membranes.

    PubMed

    Umegawa, Yuichi; Tanaka, Yuya; Nobuaki, Matsumori; Murata, Michio

    2016-03-01

    Recent advances in solid-state nuclear magnetic resonance (NMR) techniques, such as magic angle spinning and high-power decoupling, have dramatically increased the sensitivity and resolution of NMR. However, these NMR techniques generate extra heat, causing a temperature difference between the sample in the rotor and the variable temperature gas. This extra heating is a particularly crucial problem for hydrated lipid membrane samples. Thus, to develop an NMR thermometer that is suitable for hydrated lipid samples, thulium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (TmDOTA) was synthesized and labeled with (13) C (i.e., (13) C-TmDOTA) to increase the NMR sensitivity. The complex was mixed with a hydrated lipid membrane, and the system was subjected to solid-state NMR and differential scanning calorimetric analyses. The physical properties of the lipid bilayer and the quality of the NMR spectra of the membrane were negligibly affected by the presence of (13) C-TmDOTA, and the (13) C chemical shift of the complex exhibited a large-temperature dependence. The results demonstrated that (13) C-TmDOTA could be successfully used as a thermometer to accurately monitor temperature changes induced by (1) H decoupling pulses and/or by magic angle spinning and the temperature distribution of the sample inside the rotor. Thus, (13) C-TmDOTA was shown to be a versatile thermometer for hydrated lipid assemblies. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26460094

  15. (13) C-TmDOTA as versatile thermometer compound for solid-state NMR of hydrated lipid bilayer membranes.

    PubMed

    Umegawa, Yuichi; Tanaka, Yuya; Nobuaki, Matsumori; Murata, Michio

    2016-03-01

    Recent advances in solid-state nuclear magnetic resonance (NMR) techniques, such as magic angle spinning and high-power decoupling, have dramatically increased the sensitivity and resolution of NMR. However, these NMR techniques generate extra heat, causing a temperature difference between the sample in the rotor and the variable temperature gas. This extra heating is a particularly crucial problem for hydrated lipid membrane samples. Thus, to develop an NMR thermometer that is suitable for hydrated lipid samples, thulium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (TmDOTA) was synthesized and labeled with (13) C (i.e., (13) C-TmDOTA) to increase the NMR sensitivity. The complex was mixed with a hydrated lipid membrane, and the system was subjected to solid-state NMR and differential scanning calorimetric analyses. The physical properties of the lipid bilayer and the quality of the NMR spectra of the membrane were negligibly affected by the presence of (13) C-TmDOTA, and the (13) C chemical shift of the complex exhibited a large-temperature dependence. The results demonstrated that (13) C-TmDOTA could be successfully used as a thermometer to accurately monitor temperature changes induced by (1) H decoupling pulses and/or by magic angle spinning and the temperature distribution of the sample inside the rotor. Thus, (13) C-TmDOTA was shown to be a versatile thermometer for hydrated lipid assemblies. Copyright © 2015 John Wiley & Sons, Ltd.

  16. Solid-state /sup 13/C NMR and X-ray diffraction of dermatan sulfate

    SciTech Connect

    Winter, W.T.; Taylor, M.G.; Stevens, E.S.; Morris, E.R.; Rees, D.A.

    1986-05-29

    Dermatan sulfate in the solid state has been studied by /sup 13/C CP/MAS nmr and X-ray diffraction in order to establish the ring conformation of the L-iduronate moiety. The solid state nmr spectrum is similar to the solution spectrum obtained previously, indicating that a ring conformation at least approximating to /sup 1/C/sub 4/ predominates in the solid state. X-ray powder diffraction data from the same sample indicate the presence of the 8-fold helix form previously observed by fiber diffraction, and interpreted in terms of a /sup 4/C/sub 1/ ring form. A likely explanation of the results is that a distorted /sup 1/C/sub 4/ L-iduronate ring conformation, not considered in the initial X-ray analysis, may emerge to provide a satisfactory interpretation of all available physical-chemical data.

  17. /sup 13/C NMR studies of the molecular flexibility of antidepressants

    SciTech Connect

    Munro, S.L.; Andrews, P.R.; Craik, D.J.; Gale, D.J.

    1986-02-01

    The solution dynamics of a series of clinically potent antidepressants have been investigated by measuring /sup 13/C NMR relaxation parameters. Correlation times and internal motional rates were calculated from spin-lattice relaxation times and nuclear Overhauser effects for the protonated carbons in mianserin, imipramine-like antidepressants, and amitriptyline-like antidepressants. These data were interpreted in terms of overall molecular tumbling, internal rotations, and inherent flexibility of these structures. Of particular interest was the conformational variability of the tricyclic nucleus of the tricyclic antidepressants, where the data indicated a fivefold difference in mobility of the dimethylene bridge of imipramine-like antidepressants relative to amitriptyline-like compounds. The implications of such a difference in internal motions is discussed in relation to previous NMR studies and to the reported differences in pharmacological activity of these antidepressants.

  18. Total assignment of 1H and 13C NMR data for the sesquiterpene lactone 15-deoxygoyazensolide.

    PubMed

    Heleno, Vladimir Constantino Gomes; Crotti, Antônio Eduardo Miller; Constantino, Mauricio Gomes; Lopes, Norberto Peporine; Lopes, João Luis Callegari

    2004-03-01

    We describe a complete analysis of the 1H and 13C spectra of the anti-inflamatory, schistossomicidal and trypanosomicidal sesquiterpene lactone 15-deoxygoyazensolide. This lactone, with a structure similar to other important ones, was studied by NMR techniques such as COSY, HMQC, HMBC, Jres and NOE experiments. The comparison of the data with some computational results led to an unequivocal assignment of all hydrogen and carbon chemical shifts, even eliminating some previous ambiguities. We were able to determine all hydrogen coupling constants (J) and signal multiplicities and to confirm the stereochemistry. A new method for the determination of the relative position of the lactonization and the position of the ester group on a medium-sized ring by NMR was developed.

  19. 1H, 13C and 15N NMR assignments of phenazopyridine derivatives.

    PubMed

    Burgueño-Tapia, Eleuterio; Mora-Pérez, Yolanda; Morales-Ríos, Martha S; Joseph-Nathan, Pedro

    2005-03-01

    Phenazopyridine hydrochloride (1), a drug in clinical use for many decades, and some derivatives were studied by one- and two-dimensional (1)H, (13)C and (15)N NMR methodology. The assignments, combined with DFT calculations, reveal that the preferred protonation site of the drug is the pyridine ring nitrogen atom. The chemoselective acetylation of phenazopyridine (2) and its influence on the polarization of the azo nitrogen atoms were evidenced by the (15)N NMR spectra. Molecular calculations of the phenazopyridines 2-4 show that the pyridine and phenyl groups are oriented in an antiperiplanar conformation with intramolecular hydrogen bonding between the N-b atom and the C-2 amino group preserving the E-azo stereochemistry.

  20. Experimental and calculated 1H, 13C, 15N NMR spectra of famotidine

    NASA Astrophysics Data System (ADS)

    Barańska, M.; Czarniecki, K.; Proniewicz, L. M.

    2001-05-01

    Famotidine, 3-[[[2-[(aminoiminomethyl)amino]-4-thiazolyl]methyl]thio]- N-(aminosulfonyl), is a histamine H 2-receptor blocker that has been used mainly for the treatment of peptic ulcers and the Zollinger-Ellison syndrome. Its NMR spectra in different solvents were reported earlier; however, detailed interpretation has not been done thus far. In this work, experimental 1H, 13C and 15N NMR spectra of famotidine dissolved in DMSO-d 6 are shown. The assignment of observed chemical shifts is based on quantum chemical calculation at the Hartree-Fock/6-31G ∗ level. The geometry optimization of the famotidine molecule with two internal hydrogen bonds, i.e. [N(3)-H(23)⋯N(9) and N(3)⋯H(34)-N(20)], is done by using the B3LYP method with the 6-31G ∗ basis set.

  1. High resolution 13C-detected solid-state NMR spectroscopy of a deuterated protein

    PubMed Central

    Tang, Ming; Comellas, Gemma; Mueller, Leonard J.

    2011-01-01

    High resolution 13C-detected solid-state NMR spectra of the deuterated beta-1 immunoglobulin binding domain of the protein G (GB1) have been collected to show that all 15N, 13C′, 13Cα and 13Cβ sites are resolved in 13C–13C and 15N–13C spectra, with significant improvement in T2 relaxation times and resolution at high magnetic field (750 MHz). The comparison of echo T2 values between deuterated and protonated GB1 at various spinning rates and under different decoupling schemes indicates that 13Cα T2′ times increase by almost a factor of two upon deuteration at all spinning rates and under moderate decoupling strength, and thus the deuteration enables application of scalar-based correlation experiments that are challenging from the standpoint of transverse relaxation, with moderate proton decoupling. Additionally, deuteration in large proteins is a useful strategy to selectively detect polar residues that are often important for protein function and protein–protein interactions. PMID:20803233

  2. Electronic Properties and 13C NMR Structural Study of Y3N@C88

    PubMed Central

    Fu, Wujun; Zhang, Jianyuan; Champion, Hunter; Fuhrer, Tim; Azuremendi, Hugo; Zuo, Tianming; Zhang, Jianfei; Harich, Kim; Dorn, Harry C.

    2011-01-01

    In this paper we report the synthesis, purification, 13C NMR and other characterization studies of Y3N@C88. The 13C NMR, UV-vis and chromatographic data suggest an Y3N@C88 having IPR allowed cage with D2(35)-C88 symmetry. In earlier density functional theory (DFT) computational and X-ray crystallographic studies, it was reported that lanthanide (A3N)6+ clusters are stabilized in D2(35)-C88 symmetry cages and have reduced HOMO-LUMO gaps relative to other trimetallic nitride endohedral metallofullerene cage systems, for example, A3N@C80. In this paper, we report that the non-lanthanide (Y3N)6+ cluster in the D2(35)-C88 cage exhibits a HOMO-LUMO gap consistent with other lanthanide A3N@C88 molecules based on electrochemical measurements and DFT computational study. These results suggests that the reduced HOMO-LUMO gap of A3N@C88 systems is a property dominated by the D2(35)-C88 carbon cage and not f-orbital lanthanide electronic metal cluster (A3N)6+ orbital participation. PMID:21506556

  3. 1H and 13C resonance designation of antimycin A1 by two-dimensional NMR spectroscopy

    USGS Publications Warehouse

    Abidi, S.L.; Adams, B.R.

    1987-01-01

    Complete 1H and 13C resonance assignments of antimycin A1 were accomplished by two-dimensional NMR techniques, viz. 1H homonuclear COSY correlation, heteronuclear 13C-1H chemical shift correlation and long-range heteronuclear 13C-1H COLOC correlation. Antimycin A1 was found to consist of two isomeric components in a 2:1 ratio based on NMR spectroscopic evidence. The structure of the major component was newly assigned as the 8-isopentanoic acid ester. The spectra of the minor component were consistent with the known structure of antimycin A1.

  4. (13)C NMR-based metabolomics for the classification of green coffee beans according to variety and origin.

    PubMed

    Wei, Feifei; Furihata, Kazuo; Koda, Masanori; Hu, Fangyu; Kato, Rieko; Miyakawa, Takuya; Tanokura, Masaru

    2012-10-10

    (13)C NMR-based metabolomics was demonstrated as a useful tool for distinguishing the species and origins of green coffee bean samples of arabica and robusta from six different geographic regions. By the application of information on (13)C signal assignment, significantly different levels of 14 metabolites of green coffee beans were identified in the classifications, including sucrose, caffeine, chlorogenic acids, choline, amino acids, organic acids, and trigonelline, as captured by multivariate analytical models. These studies demonstrate that the species and geographical origin can be quickly discriminated by evaluating the major metabolites of green coffee beans quantitatively using (13)C NMR-based metabolite profiling.

  5. Experimental (FT-IR, FT-Raman, UV and NMR) and quantum chemical studies on molecular structure, spectroscopic analysis, NLO, NBO and reactivity descriptors of 3,5-Difluoroaniline.

    PubMed

    Pathak, S K; Srivastava, R; Sachan, A K; Prasad, O; Sinha, L; Asiri, A M; Karabacak, M

    2015-01-25

    Comprehensive investigation of geometrical and electronic structure in ground as well as the first excited state of 3,5-Difluoroaniline (C6H5NF2) was carried out. The experimentally observed spectral data (FT-TR and FT-Raman) of the title compound was compared with the spectral data obtained by DFT/B3LYP method using 6-311++G(d,p) basis set. The molecular properties like dipole moment, polarizability, first static hyperpolarizability, molecular electrostatic potential surface (MEPs), and contour map were calculated to get a better insight of the properties of the title molecule. Natural bond orbital (NBO) analysis was applied to study stability of the molecule arising from charge delocalization. UV-Vis spectrum of the title compound was also recorded and the electronic properties, such as Frontier orbitals and band gap energies were measured by TD-DFT approach. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. Global and local reactivity descriptors were computed to predict reactivity and reactive sites on the molecule. (1)H and (13)C NMR spectra by using gauge including atomic orbital (GIAO) method of studied compound were compared with experimental data obtained. Moreover, the thermodynamic properties were evaluated. PMID:25078461

  6. Spectroscopic characterization of the 1-substituted 3,3-diphenyl-4-(2'-hydroxyphenyl)azetidin-2-ones: Application of 13C NMR, 1H- 13C COSY NMR and mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Singh, Girija S.; Pheko, Tshepo

    2008-08-01

    The article deals with spectroscopic characterization of azetidin-2-ones. The presence of substituents like hydroxyl, fluoro, methoxy and benzhydryl, etc., on the azetidin-2-one ring significantly affects the IR absorption and 13C NMR frequencies of the carbonyl group present in these compounds. The presence of an ester carbonyl group or too many methine protons in the molecule has been observed to limit the scope of IR and 1H NMR spectroscopy in unambiguous assignment of the structure. The application of 13C NMR, 2D NMR ( 1H- 13C COSY) and mass spectroscopy in characterization of complex azetidin-2-ones is discussed. An application of the latter two techniques is described in deciding unequivocally between an azetidin-2-one ring and chroman-2-one ring structure for the product obtained by treatment of the 1-substituted 3,3-diphenyl-4-[2'-( O-diphenylacyl)hydroxyphenyl]-2-azetidinones with ethanolic sodium hydroxide at room temperature.

  7. The Ratio of Acetate-to-Glucose Oxidation in Astrocytes from a Single 13C NMR Spectrum of Cerebral Cortex

    PubMed Central

    Marin-Valencia, Isaac; Hooshyar, M. Ali; Pichumani, Kumar; Sherry, A. Dean; Malloy, Craig R.

    2014-01-01

    The 13C labeling patterns in glutamate and glutamine from brain tissue are quite different after infusion of a mixture of 13C-enriched glucose and acetate. Two processes contribute to this observation, oxidation of acetate by astrocytes but not neurons, and preferential incorporation of α-ketoglutarate into glutamate in neurons, and incorporation of α-ketoglutarate into glutamine in astrocytes. The acetate:glucose ratio, introduced previously for analysis of a single 13C NMR spectrum, provides a useful index of acetate and glucose oxidation in the brain tissue. However, quantitation of relative substrate oxidation at the cell compartment level has not been reported. A simple mathematical method is presented to quantify the ratio of acetate to glucose oxidation in astrocytes, based on the standard assumption that neurons do not oxidize acetate. Mice were infused with [1,2-13C]acetate and [1,6-13C]glucose, and proton decoupled 13C NMR spectra of cortex extracts were acquired. A fit of those spectra to the model indicated that 13C-labeled acetate and glucose contributed approximately equally to acetyl-CoA (0.96) in astrocytes. Since this method relies on a single 13C NMR spectrum, it can be readily applied to multiple physiologic and pathologic conditions. PMID:25231025

  8. Topotecan dynamics, tautomerism and reactivity--1H/13C NMR and ESI MS study.

    PubMed

    Hyz, Karolina; Kawecki, Robert; Bednarek, Elzbieta; Bocian, Wojciech; Sitkowski, Jerzy; Kozerski, Lech

    2010-08-01

    Topotecan (TPT) is in clinical use as an antitumor agent, hycamtin. Because of this, it requires both biologically and chemically useful information to be available. TPT acts by binding to the covalent complex formed by nicked DNA and topoisomerase I. This has a poisonous effect since inserted into the single-strand nick and TPT inhibits its religation. We used NMR to trace TPT dynamics, tautomerism and solvolysis products in various solvents and conditions. Chemical stability was assessed in methanol and DMSO as compared to water, and the regioselectivity of the N- and O-methylation was studied using various alkylating agents. The reaction products of quaternization of the nitrogen atom and methylation of the oxygen atom were characterized by means of ESI MS, (1)H/(13)C-HMBC and -HSQCAD NMR. We have focused on the NMR characterization of TPT with an anticipation that its aggregation, tumbling properties and the intramolecular dipolar interactions will be a common feature for other compounds described in this article. These features can also be useful in tracing the interactions of this class of topoisomerase I (TopoI) poisons with DNA. Moreover, the results explained shed light on the recently disclosed problem of lack of stability of TPT in the heart tissue homogenate samples using the analytical assays developed for this class of compounds carried out in the presence of methanol. PMID:20623719

  9. 1H-detected 13C Photo-CIDNP as a Sensitivity Enhancement Tool in Solution NMR

    PubMed Central

    Lee, Jung Ho; Sekhar, Ashok; Cavagnero, Silvia

    2011-01-01

    NMR is a powerful yet intrinsically insensitive technique. The applicability of NMR to chemical and biological systems would be substantially extended by new approaches going beyond current signal-to-noise capabilities. Here, we exploit the large enhancements arising from 13C photo-chemically induced dynamic nuclear polarization (13C photo-CIDNP) in solution to improve biomolecular NMR sensitivity in the context of heteronuclear correlation spectroscopy. The 13C-PRINT pulse sequence presented here involves an initial 13C nuclear spin polarization via photo-CIDNP followed by conversion to antiphase coherence and transfer to 1H for detection. We observe substantial enhancements, up to ≫200-fold, relative to the dark (laser off) experiment. Resonances of both side-chain and backbone CH pairs are enhanced for the three aromatic residues Trp, His and Tyr and the Trp-containing σ32 peptide. The sensitivity of this experiment, defined as signal-to-noise per unit time (S/N)t, is unprecedented in the NMR polarization enhancement literature dealing with polypeptides in solution. Up to a 16-fold larger (S/N)t than the 1H-13C SE-HSQC reference sequence is achieved, for the σ32 peptide. This gain leads to a reduction in data collection time up to 256-fold, highlighting the advantages of 1H-detected 13C photo-CIDNP in solution NMR. PMID:21548581

  10. Simultaneous steady-state and dynamic 13C NMR can differentiate alternative routes of pyruvate metabolism in living cancer cells.

    PubMed

    Yang, Chendong; Harrison, Crystal; Jin, Eunsook S; Chuang, David T; Sherry, A Dean; Malloy, Craig R; Merritt, Matthew E; DeBerardinis, Ralph J

    2014-02-28

    Metabolic reprogramming facilitates cancer cell growth, so quantitative metabolic flux measurements could produce useful biomarkers. However, current methods to analyze flux in vivo provide either a steady-state overview of relative activities (infusion of (13)C and analysis of extracted metabolites) or a dynamic view of a few reactions (hyperpolarized (13)C spectroscopy). Moreover, although hyperpolarization has successfully quantified pyruvate-lactate exchanges, its ability to assess mitochondrial pyruvate metabolism is unproven in cancer. Here, we combined (13)C hyperpolarization and isotopomer analysis to quantify multiple fates of pyruvate simultaneously. Two cancer cell lines with divergent pyruvate metabolism were incubated with thermally polarized [3-(13)C]pyruvate for several hours, then briefly exposed to hyperpolarized [1-(13)C]pyruvate during acquisition of NMR spectra using selective excitation to maximize detection of H[(13)C]O3(-) and [1-(13)C]lactate. Metabolites were then extracted and subjected to isotopomer analysis to determine relative rates of pathways involving [3-(13)C]pyruvate. Quantitation of hyperpolarized H[(13)C]O3(-) provided a single definitive metabolic rate, which was then used to convert relative rates derived from isotopomer analysis into quantitative fluxes. This revealed that H[(13)C]O3(-) appearance reflects activity of pyruvate dehydrogenase rather than pyruvate carboxylation followed by subsequent decarboxylation reactions. Glucose substantially altered [1-(13)C]pyruvate metabolism, enhancing exchanges with [1-(13)C]lactate and suppressing H[(13)C]O3(-) formation. Furthermore, inhibiting Akt, an oncogenic kinase that stimulates glycolysis, reversed these effects, indicating that metabolism of pyruvate by both LDH and pyruvate dehydrogenase is subject to the acute effects of oncogenic signaling on glycolysis. The data suggest that combining (13)C isotopomer analyses and dynamic hyperpolarized (13)C spectroscopy may enable

  11. Simultaneous Steady-state and Dynamic 13C NMR Can Differentiate Alternative Routes of Pyruvate Metabolism in Living Cancer Cells*

    PubMed Central

    Yang, Chendong; Harrison, Crystal; Jin, Eunsook S.; Chuang, David T.; Sherry, A. Dean; Malloy, Craig R.; Merritt, Matthew E.; DeBerardinis, Ralph J.

    2014-01-01

    Metabolic reprogramming facilitates cancer cell growth, so quantitative metabolic flux measurements could produce useful biomarkers. However, current methods to analyze flux in vivo provide either a steady-state overview of relative activities (infusion of 13C and analysis of extracted metabolites) or a dynamic view of a few reactions (hyperpolarized 13C spectroscopy). Moreover, although hyperpolarization has successfully quantified pyruvate-lactate exchanges, its ability to assess mitochondrial pyruvate metabolism is unproven in cancer. Here, we combined 13C hyperpolarization and isotopomer analysis to quantify multiple fates of pyruvate simultaneously. Two cancer cell lines with divergent pyruvate metabolism were incubated with thermally polarized [3-13C]pyruvate for several hours, then briefly exposed to hyperpolarized [1-13C]pyruvate during acquisition of NMR spectra using selective excitation to maximize detection of H[13C]O3− and [1-13C]lactate. Metabolites were then extracted and subjected to isotopomer analysis to determine relative rates of pathways involving [3-13C]pyruvate. Quantitation of hyperpolarized H[13C]O3− provided a single definitive metabolic rate, which was then used to convert relative rates derived from isotopomer analysis into quantitative fluxes. This revealed that H[13C]O3− appearance reflects activity of pyruvate dehydrogenase rather than pyruvate carboxylation followed by subsequent decarboxylation reactions. Glucose substantially altered [1-13C]pyruvate metabolism, enhancing exchanges with [1-13C]lactate and suppressing H[13C]O3− formation. Furthermore, inhibiting Akt, an oncogenic kinase that stimulates glycolysis, reversed these effects, indicating that metabolism of pyruvate by both LDH and pyruvate dehydrogenase is subject to the acute effects of oncogenic signaling on glycolysis. The data suggest that combining 13C isotopomer analyses and dynamic hyperpolarized 13C spectroscopy may enable quantitative flux measurements in

  12. Precision FT-IR laboratory measurements of atmospheric molecule

    NASA Astrophysics Data System (ADS)

    Sung, K.; Brown, L. R.; Crawford, T. J.

    2014-12-01

    Spectroscopic information is crucial a priori input to interpret atmospheric spectroscopic observations through radiative transfer modeling. The spectroscopic observations lead us to determine the physical and chemical conditions (e.g., atmospheric pressure, temperatures, composition, abundances …). In order to avoid false interpretations of the observed spectra, the molecular spectroscopic information (either line parameters or cross sections) must be sufficiently accurate and complete. To achieve this goal, we employ a broad-band Fourier transform spectrometer, Bruker IFS-125HR equipped with multiple detectors (He-cooled bolometers, N2-cooled MCT and InSb, warm InGaAs, Boron-doped silicates, photodiode) and beamsplitters (Mylars, KBr, CaF2, Quartz) sufficient to cover entire infrared spectra region from 20 to 15000 cm-1. We vacuum-couple up to 15 different absorption cells to the FT-IR, including five coolable cells with optical path lengths ranging from 0.02 m to 52 m; three of them are capable of reaching temperatures down to 50 K. We also have one heatable cell reaching 400 K. Finally, an extra vacuum chamber newly implemented to the Bruker 125HR enables both emission and absorption spectroscopy utilizing the emission port of the FT-IR. Recently, several studies of atmospheric molecules have been completed using the FT-IR at JPL in support of the Earth, terrestrial and planetary atmospheric remote sensing. These include analyses of C3H8 (propane) and 16O12C17O mid- and near-infrared regions, 13C12CH6 and 12C2H6 at longer wavelengths. In addition, we are studying the O2(A) line mixing and collision-induced absorption in the O2 A-band at 0.76 μm, as well as temperature-dependent cross sections of C6H6 (benzene) and C3H6 (propene) in the mid-infrared region. We will present an overview of results and work in progress. [Research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, Connecticut College, and

  13. Determination of glucan phosphorylation using heteronuclear 1H, 13C double and 1H, 13C, 31P triple-resonance NMR spectra.

    PubMed

    Schmieder, Peter; Nitschke, Felix; Steup, Martin; Mallow, Keven; Specker, Edgar

    2013-10-01

    Phosphorylation and dephosphorylation of starch and glycogen are important for their physicochemical properties and also their physiological functions. It is therefore desirable to reliably determine the phosphorylation sites. Heteronuclear multidimensional NMR-spectroscopy is in principle a straightforward analytical approach even for complex carbohydrate molecules. With heterogeneous samples from natural sources, however, the task becomes more difficult because a full assignment of the resonances of the carbohydrates is impossible to obtain. Here, we show that the combination of heteronuclear (1) H,(13) C and (1) H,(13) C,(31) P techniques and information derived from spectra of a set of reference compounds can lead to an unambiguous determination of the phosphorylation sites even in heterogeneous samples. PMID:23913630

  14. Determination of glucan phosphorylation using heteronuclear 1H, 13C double and 1H, 13C, 31P triple-resonance NMR spectra.

    PubMed

    Schmieder, Peter; Nitschke, Felix; Steup, Martin; Mallow, Keven; Specker, Edgar

    2013-10-01

    Phosphorylation and dephosphorylation of starch and glycogen are important for their physicochemical properties and also their physiological functions. It is therefore desirable to reliably determine the phosphorylation sites. Heteronuclear multidimensional NMR-spectroscopy is in principle a straightforward analytical approach even for complex carbohydrate molecules. With heterogeneous samples from natural sources, however, the task becomes more difficult because a full assignment of the resonances of the carbohydrates is impossible to obtain. Here, we show that the combination of heteronuclear (1) H,(13) C and (1) H,(13) C,(31) P techniques and information derived from spectra of a set of reference compounds can lead to an unambiguous determination of the phosphorylation sites even in heterogeneous samples.

  15. A 13C NMR study of the structure of four cinnamic acids and their methyl esters

    NASA Astrophysics Data System (ADS)

    Silva, A. M. S.; Alkorta, I.; Elguero, J.; Silva, V. L. M.

    2001-09-01

    The 13C NMR spectra, both in DMSO solution and in the solid state of four cinnamic acids ( p-methoxy, p-hydroxy, p-methyl, p-chloro) and their corresponding methyl esters have been recorded. The two main results in the solid state are: (i) the only significant difference between acids and esters chemical shifts concerns the CO group which, on average, appears at 173 ppm in the acids and 168 ppm in the esters; (ii) the signals of the ortho and meta carbons both in the acids and the esters are splitted. The two 'anomalies' disappear in DMSO solution. These observations can be rationalized using simple GIAO/B3LYP/6-31G ∗ calculations.

  16. The effect of sample hydration on 13C CPMAS NMR spectra of fulvic acids

    USGS Publications Warehouse

    Hatcher, P.G.; Wilson, M.A.

    1991-01-01

    Three fulvic acids, two of which have been well studied by a number of other groups (Armadale and Suwannee river fulvic acids) have been examined by high resolution solid-state 13C-NMR techniques to delineate the effect of absorbed water. Two main effects of absorbed water were observed: (1) changes in spin lattice relaxation times in the rotating frame and cross polarization times and (2) total loss of signal so that some fulvic acid is effectively in solution. These results suggest that discrepancies in the literature concerning observed relative signal intensities from different structural groups are due to absorbed water and emphasize the necessity for proper precautionary drying before spectroscopic analysis. ?? 1991.

  17. Acetate and Bicarbonate Assimilation and Metabolite Formation in Chlamydomonas reinhardtii: A 13C-NMR Study

    PubMed Central

    Singh, Himanshu; Shukla, Manish R.; Chary, Kandala V. R.; Rao, Basuthkar J.

    2014-01-01

    Cellular metabolite analyses by 13C-NMR showed that C. reinhardtii cells assimilate acetate at a faster rate in heterotrophy than in mixotrophy. While heterotrophic cells produced bicarbonate and CO2aq, mixotrophy cells produced bicarbonate alone as predominant metabolite. Experiments with singly 13C-labelled acetate (13CH3-COOH or CH3-13COOH) supported that both the 13C nuclei give rise to bicarbonate and CO2aq. The observed metabolite(s) upon further incubation led to the production of starch and triacylglycerol (TAG) in mixotrophy, whereas in heterotrophy the TAG production was minimal with substantial accumulation of glycerol and starch. Prolonged incubation up to eight days, without the addition of fresh acetate, led to an increased TAG production at the expense of bicarbonate, akin to that of nitrogen-starvation. However, such TAG production was substantially high in mixotrophy as compared to that in heterotrophy. Addition of mitochondrial un-coupler blocked the formation of bicarbonate and CO2aq in heterotrophic cells, even though acetate uptake ensued. Addition of PSII-inhibitor to mixotrophic cells resulted in partial conversion of bicarbonate into CO2aq, which were found to be in equilibrium. In an independent experiment, we have monitored assimilation of bicarbonate via photoautotrophy and found that the cells indeed produce starch and TAG at a much faster rate as compared to that in mixotrophy and heterotrophy. Further, we noticed that the accumulation of starch is relatively more as compared to TAG. Based on these observations, we suggest that acetate assimilation in C. reinhardtii does not directly lead to TAG formation but via bicarbonate/CO2aq pathways. Photoautotrophic mode is found to be the best growth condition for the production of starch and TAG and starch in C. reinhardtii. PMID:25207648

  18. 13C solid-state NMR analysis of heterogeneous structure of beeswax in native state

    NASA Astrophysics Data System (ADS)

    Kameda, Tsunenori

    2005-12-01

    I investigated the molecular structure of natural wax from Japanese bees (Apis cerana japonica) in its native state (neither purified nor recrystallized) by 13C and 1H solid-state NMR. Two strong 13C peaks at 32.9 and 34.0 ppm were attributed to signals from internal-chain methylene carbons [int-(CH2)] in two types of crystal form. The peak at 32.9 ppm was assigned to an orthorhombic crystal form, and that at 34.0 ppm was assigned to a triclinic or monoclinic form. In both crystalline regions, bi-exponential decay of 13C spin-lattice relaxation [T1(C)] for the crystalline peaks due to chain diffusion was observed. 1H spin-lattice relaxation [T1(H)] values for protons of the CH3 group and for int-(CH2) in the crystalline and amorphous regions were identical; this was interpreted as being due to averaging of the T1(H) relaxation rates via spin diffusion. In contrast, although the T_{{1}_{\\rho}}(H) decay curves for protons of the CH3 group and for int-(CH2) in the amorphous and orthorhombic forms were almost identical, those of the triclinic or monoclinic forms were different. This unhomogeneous character of T_{{1}_{\\rho}}(H) was interpreted as resulting from differences in the molecular composition of each crystal form. Moreover, two components with long and short 1H spin-spin relaxation [T2(H)] values, arising from the mobile and rigid phases, respectively, were observed at above about -30 °C.

  19. Solid-state (13)C NMR reveals effects of temperature and hydration on elastin.

    PubMed Central

    Perry, Ashlee; Stypa, Michael P; Tenn, Brandon K; Kumashiro, Kristin K

    2002-01-01

    Elastin is the principal protein component of the elastic fiber in vertebrate tissue. The waters of hydration in the elastic fiber are believed to play a critical role in the structure and function of this largely hydrophobic, amorphous protein. (13)C CPMAS NMR spectra are acquired for elastin samples with different hydration levels. The spectral intensities in the aliphatic region undergo significant changes as 70% of the water in hydrated elastin is removed. In addition, dramatic differences in the CPMAS spectra of hydrated, lyophilized, and partially dehydrated elastin samples over a relatively small temperature range (-20 degrees C to 37 degrees C) are observed. Results from other experiments, including (13)C T(1) and (1)H T(1 rho) measurements, direct polarization with magic-angle spinning, and static CP of the hydrated and lyophilized elastin preparations, also support the model that there is significant mobility in fully hydrated elastin. Our results support models in which water plays an integral role in the structure and proper function of elastin in vertebrate tissue. PMID:11806948

  20. Partial 13C isotopic enrichment of nucleoside monophosphates: useful reporters for NMR structural studies

    PubMed Central

    Kishore, Anita I.; Mayer, Michael R.; Prestegard, James H.

    2005-01-01

    Analysis of the 13C isotopic labeling patterns of nucleoside monophosphates (NMPs) extracted from Escherichia coli grown in a mixture of C-1 and C-2 glucose is presented. By comparing our results to previous observations on amino acids grown in similar media, we have been able to rationalize the labeling pattern based on the well-known biochemistry of nucleotide biosynthesis. Except for a few notable absences of label (C4 in purines and C3′ in ribose) and one highly enriched site (C1′ in ribose), most carbons are randomly enriched at a low level (an average of 13%). These sparsely labeled NMPs give less complex NMR spectra than their fully isotopically labeled analogs due to the elimination of most 13C–13C scalar couplings. The spectral simplicity is particularly advantageous when working in ordered systems, as illustrated with guanosine diphosphate (GDP) bound to ADP ribosylation factor 1 (ARF1) aligned in a liquid crystalline medium. In this system, the absence of scalar couplings and additional long-range dipolar couplings significantly enhances signal to noise and resolution. PMID:16254075

  1. Mapping cerebral glutamate 13C turnover and oxygen consumption by in vivo NMR.

    PubMed

    Hyder, Fahmeed; Brown, Peter; Nixon, Terennce W; Behar, Kevin L

    2003-01-01

    Regional rates of 13C incorporation from glucose to glutamate were detected in anesthetized rat brain in vivo at 7T with high temporal and spatial resolution using NMR method ICED PEPSI (in vivo carbon edited detection with proton echo planar spectroscopic imaging). Time courses of regional glutamate 13C turnover were fitted by a metabolic model to obtain regional tri-carboxylic acid (TCA) cycle flux and cerebral metabolic rate of oxygen consumption (CMRO2) in each voxel (8 microL) of rat cortex. CMRO2 maps obtained for rats under either alpha-chloralose or morphine anesthesia revealed average cortical values of 1.5 +/- 0.2 (n = 3) and 3.2 +/- 0.3 (n = 4) mumol/g/min, respectively. These values of CMRO2 are in good agreement with previous cortical measurements with coarser spatial resolution. The heterogeneity within each map, which depicted predominantly gray and white matter differences, was significantly greater under morphine (higher cortical activity) than under-alpha-chloralose (lower cortical activity) anesthesia. The regional variations in the basal awake state, which are expected to be even greater, should be considered to avoid partial-volume artifacts in functional activation studies of awake subjects. PMID:14562702

  2. Cigarette butt decomposition and associated chemical changes assessed by 13C CPMAS NMR.

    PubMed

    Bonanomi, Giuliano; Incerti, Guido; Cesarano, Gaspare; Gaglione, Salvatore A; Lanzotti, Virginia

    2015-01-01

    Cigarette butts (CBs) are the most common type of litter on earth, with an estimated 4.5 trillion discarded annually. Apart from being unsightly, CBs pose a serious threat to living organisms and ecosystem health when discarded in the environment because they are toxic to microbes, insects, fish and mammals. In spite of the CB toxic hazard, no studies have addressed the effects of environmental conditions on CB decomposition rate. In this study we investigate the interactive effects of substrate fertility and N transfer dynamics on CB decomposition rate and carbon quality changes. We carried out an experiment using smoked CBs and wood sticks, used as a slow decomposing standard organic substrate, incubated in both laboratory and field conditions for two years. CB carbon quality changes during decomposition was assessed by 13C CPMAS NMR. Our experiment confirmed the low degradation rate of CBs which, on average, lost only 37.8% of their initial mass after two years of decomposition. Although a net N transfer occurred from soil to CBs, contrary to our hypothesis, mass loss in the medium-term (two years) was unaffected by N availability in the surrounding substrate. The opposite held for wood sticks, in agreement with the model that N-rich substrates promote the decomposition of other N-poor natural organic materials with a high C/N ratio. As regards CB chemical quality, after two years of decomposition 13C NMR spectroscopy highlighted very small changes in C quality that are likely to reflect a limited microbial attack.

  3. Cigarette Butt Decomposition and Associated Chemical Changes Assessed by 13C CPMAS NMR

    PubMed Central

    Bonanomi, Giuliano; Incerti, Guido; Cesarano, Gaspare; Gaglione, Salvatore A.; Lanzotti, Virginia

    2015-01-01

    Cigarette butts (CBs) are the most common type of litter on earth, with an estimated 4.5 trillion discarded annually. Apart from being unsightly, CBs pose a serious threat to living organisms and ecosystem health when discarded in the environment because they are toxic to microbes, insects, fish and mammals. In spite of the CB toxic hazard, no studies have addressed the effects of environmental conditions on CB decomposition rate. In this study we investigate the interactive effects of substrate fertility and N transfer dynamics on CB decomposition rate and carbon quality changes. We carried out an experiment using smoked CBs and wood sticks, used as a slow decomposing standard organic substrate, incubated in both laboratory and field conditions for two years. CB carbon quality changes during decomposition was assessed by 13C CPMAS NMR. Our experiment confirmed the low degradation rate of CBs which, on average, lost only 37.8% of their initial mass after two years of decomposition. Although a net N transfer occurred from soil to CBs, contrary to our hypothesis, mass loss in the medium-term (two years) was unaffected by N availability in the surrounding substrate. The opposite held for wood sticks, in agreement with the model that N-rich substrates promote the decomposition of other N-poor natural organic materials with a high C/N ratio. As regards CB chemical quality, after two years of decomposition 13C NMR spectroscopy highlighted very small changes in C quality that are likely to reflect a limited microbial attack. PMID:25625643

  4. FT-IR, FT-Raman spectra and DFT calculations of melaminium perchlorate monohydrate

    NASA Astrophysics Data System (ADS)

    Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Renganathan, N. G.; Gunasekaran, S.; Anbalagan, G.

    2013-08-01

    Melaminium perchlorate monohydrate (MPM), an organic material has been synthesized by slow solvent evaporation method at room temperature. Powder X-ray diffraction analysis confirms that MPM crystal belongs to triclinic system with space group P-1. FTIR and FT Raman spectra are recorded at room temperature. Functional group assignment has been made for the melaminium cations and perchlorate anions. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory (DFT) calculations using Firefly (PC GAMESS) version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with experimental values. The assignment of the bands has been made on the basis of the calculated PED. The Mulliken charges, HOMO-LUMO orbital energies are analyzed directly from Firefly program log files and graphically illustrated. HOMO-LUMO energy gap and other related molecular properties are also calculated. The theoretically constructed FT-IR and FT-Raman spectra of MPM coincide with the experimental one. The chemical structure of the compound has been established by 1H and 13C NMR spectra. No detectable signal was observed during powder test for second harmonic generation.

  5. Synthesis, NMR, FT-IR, X-ray structural characterization, DFT analysis and isomerism aspects of 5-(2,6-dichlorobenzylidene)pyrimidine-2,4,6(1H,3H,5H)-trione

    NASA Astrophysics Data System (ADS)

    Barakat, Assem; Al-Najjar, Hany J.; Al-Majid, Abdullah Mohammed; Soliman, Saied M.; Mabkhot, Yahia Nasser; Shaik, Mohammed Rafi; Ghabbour, Hazem A.; Fun, Hoong-Kun

    2015-08-01

    The synthesis and spectral characterization of the 5-(2,6-dichlorobenzylidene)pyrimidine-2,4,6(1H,3H,5H)-trione;3 was reported. The solid state molecular structure of 3 was studied using X-ray crystallography. The relative stabilities of the seven possible isomers of 3 were calculated by DFT/B3LYP method using 6-311G(d,p) basis set. The calculated total energies and thermodynamic parameters were used to predict the relative stabilities of these isomers. The effect of solvent polarity on the relative stability of these isomers was studied at the same level of theory using PCM. It was found that the keto form, (T0), is the most stable isomer both in the gaseous state and solution. In solution, the calculated total energies of all isomers are decreased indicating that all isomers are stabilized by the solvent effect. The vibrational spectra of the most stable isomer, 3(T0) are calculated using the same level of theory and the results are compared with the experimentally measured FTIR spectra. Good correlation was obtained between the experimental and calculated vibrational frequencies (R2 = 0.9992). The electronic spectra of 3(T0) in gas phase as well as in solutions were calculated using the TD-DFT method. All the predicted electronic transitions showed very little spectral shifts and increase in the intensity of absorption due to solvent effect. Also the 1H- and 13C-NMR chemical shifts of the stable isomer were calculated and the results were correlated with the experimental data. Good correlations between the experimental and calculated chemical shifts were obtained.

  6. Synthesis, NMR, FT-IR, X-ray structural characterization, DFT analysis and isomerism aspects of 5-(2,6-dichlorobenzylidene)pyrimidine-2,4,6(1H,3H,5H)-trione.

    PubMed

    Barakat, Assem; Al-Najjar, Hany J; Al-Majid, Abdullah Mohammed; Soliman, Saied M; Mabkhot, Yahia Nasser; Shaik, Mohammed Rafi; Ghabbour, Hazem A; Fun, Hoong-Kun

    2015-08-01

    The synthesis and spectral characterization of the 5-(2,6-dichlorobenzylidene)pyrimidine-2,4,6(1H,3H,5H)-trione;3 was reported. The solid state molecular structure of 3 was studied using X-ray crystallography. The relative stabilities of the seven possible isomers of 3 were calculated by DFT/B3LYP method using 6-311 G(d,p) basis set. The calculated total energies and thermodynamic parameters were used to predict the relative stabilities of these isomers. The effect of solvent polarity on the relative stability of these isomers was studied at the same level of theory using PCM. It was found that the keto form, (T0), is the most stable isomer both in the gaseous state and solution. In solution, the calculated total energies of all isomers are decreased indicating that all isomers are stabilized by the solvent effect. The vibrational spectra of the most stable isomer, 3(T0) are calculated using the same level of theory and the results are compared with the experimentally measured FTIR spectra. Good correlation was obtained between the experimental and calculated vibrational frequencies (R(2)=0.9992). The electronic spectra of 3(T0) in gas phase as well as in solutions were calculated using the TD-DFT method. All the predicted electronic transitions showed very little spectral shifts and increase in the intensity of absorption due to solvent effect. Also the (1)H- and (13)C-NMR chemical shifts of the stable isomer were calculated and the results were correlated with the experimental data. Good correlations between the experimental and calculated chemical shifts were obtained.

  7. NBO, NMR, UV, FT-IR, FT-Raman spectra and molecular structure (monomeric and dimeric structures) investigation of 4-Chloro-3,5-Xylenol: a combined experimental and theoretical study.

    PubMed

    Arivazhagan, M; Gayathri, R

    2013-12-01

    In this work, a joint experimental (FTIR and FT-Raman) and theoretical (DFT and ab initio) study on the structure and the vibrations of 4-Chloro-3,5-Xylenol (CXL) are compared and analyzed. CXL is a chlorinated phenolic antiseptic which is a bactericide against most gram-positive bacteria. The first hyperpolarizability (β0) of this novel molecular system and related non-linear properties of CXL are calculated using HF/6-311++G(d,p) method on the finite-field approach. The energy and oscillator strength calculated using absorption spectra (UV-Vis spectrum), this spectral analysis confirms the charge transfer of the molecule. The theoretical (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge Including Atomic Orbital (GIAO) method, to analyze the molecular environment as well as the delocalization activities of electron clouds. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (χ), chemical hardness (η), first electron excitation energy (τ) and electrophilicity index (ω) as well as local reactivity (S) analyzed using HOMO and LUMO energies; the energy band gap are also determined. NBO analysis shows that charge in electron density(ED) in the σ(*) and π(*) antibonding orbitals and E((2)) energies confirms the occurrence of ICT (Intramolecular Charge Transfer) within the molecule. Inter molecular hydrogen bonds exist between -OH group, give the evidence for the formation of dimer entities in the title molecule. The influences of chlorine atom, hydroxyl group and methyl group on the geometry of benzene and its normal modes of vibrations (monomer and dimer of CXL) have also been discussed. Finally the calculated results were applied to simulate Infrared and Raman spectra of the title molecule which show good agreement with observed spectra.

  8. NBO, NMR, UV, FT-IR, FT-Raman spectra and molecular structure (monomeric and dimeric structures) investigation of 4-Chloro-3,5-Xylenol: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Arivazhagan, M.; Gayathri, R.

    2013-12-01

    In this work, a joint experimental (FTIR and FT-Raman) and theoretical (DFT and ab initio) study on the structure and the vibrations of 4-Chloro-3,5-Xylenol (CXL) are compared and analyzed. CXL is a chlorinated phenolic antiseptic which is a bactericide against most gram-positive bacteria. The first hyperpolarizability (β0) of this novel molecular system and related non-linear properties of CXL are calculated using HF/6-311++G(d,p) method on the finite-field approach. The energy and oscillator strength calculated using absorption spectra (UV-Vis spectrum), this spectral analysis confirms the charge transfer of the molecule. The theoretical 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge Including Atomic Orbital (GIAO) method, to analyze the molecular environment as well as the delocalization activities of electron clouds. The directly calculated ionization potential (IP), electron affinity (EA), electronegativity (χ), chemical hardness (η), first electron excitation energy (τ) and electrophilicity index (ω) as well as local reactivity (S) analyzed using HOMO and LUMO energies; the energy band gap are also determined. NBO analysis shows that charge in electron density(ED) in the σ* and π* antibonding orbitals and E(2) energies confirms the occurrence of ICT (Intramolecular Charge Transfer) within the molecule. Inter molecular hydrogen bonds exist between -OH group, give the evidence for the formation of dimer entities in the title molecule. The influences of chlorine atom, hydroxyl group and methyl group on the geometry of benzene and its normal modes of vibrations (monomer and dimer of CXL) have also been discussed. Finally the calculated results were applied to simulate Infrared and Raman spectra of the title molecule which show good agreement with observed spectra.

  9. Quantitative 13C NMR of whole and fractionated Iowa Mollisols for assessment of organic matter composition

    NASA Astrophysics Data System (ADS)

    Fang, Xiaowen; Chua, Teresita; Schmidt-Rohr, Klaus; Thompson, Michael L.

    2010-01-01

    Both the concentrations and the stocks of soil organic carbon vary across the landscape. Do the amounts of recalcitrant components of soil organic matter (SOM) vary with landscape position? To address this question, we studied four Mollisols in central Iowa, two developed in till and two developed in loess. Two of the soils were well drained and two were poorly drained. We collected surface-horizon samples and studied organic matter in the particulate organic matter (POM) fraction, the clay fractions, and the whole, unfractionated samples. We treated the soil samples with 5 M HF at ambient temperature or at 60 °C for 30 min to concentrate the SOM. To assess the composition of the SOM, we used solid-state nuclear magnetic resonance (NMR) spectroscopy, in particular, quantitative 13C DP/MAS (direct-polarization/magic-angle spinning), with and without recoupled dipolar dephasing. Spin counting by correlation of the integral NMR intensity with the C concentration by elemental analysis showed that NMR was ⩾85% quantitative for the majority of the samples studied. For untreated whole-soil samples with <2.5 wt.% C, which is considerably less than in most previous quantitative NMR analyses of SOM, useful spectra that reflected ⩾65% of all C were obtained. The NMR analyses allowed us to conclude (1) that the HF treatment (with or without heat) had low impact on the organic C composition in the samples, except for protonating carboxylate anions to carboxylic acids, (2) that most organic C was observable by NMR even in untreated soil materials, (3) that esters were likely to compose only a minor fraction of SOM in these Mollisols, and (4) that the aromatic components of SOM were enriched to ˜53% in the poorly drained soils, compared with ˜48% in the well drained soils; in plant tissue and particulate organic matter (POM) the aromaticities were ˜18% and ˜32%, respectively. Nonpolar, nonprotonated aromatic C, interpreted as a proxy for charcoal C, dominated the

  10. Dynamic nuclear polarization-enhanced 1H-13C double resonance NMR in static samples below 20 K

    NASA Astrophysics Data System (ADS)

    Potapov, Alexey; Thurber, Kent R.; Yau, Wai-Ming; Tycko, Robert

    2012-08-01

    We demonstrate the feasibility of one-dimensional and two-dimensional 1H-13C double resonance NMR experiments with dynamic nuclear polarization (DNP) at 9.4 T and temperatures below 20 K, including both 1H-13C cross-polarization and 1H decoupling, and discuss the effects of polarizing agent type, polarizing agent concentration, temperature, and solvent deuteration. We describe a two-channel low-temperature DNP/NMR probe, capable of carrying the radio-frequency power load required for 1H-13C cross-polarization and high-power proton decoupling. Experiments at 8 K and 16 K reveal a significant T2 relaxation of 13C, induced by electron spin flips. Carr-Purcell experiments and numerical simulations of Carr-Purcell dephasing curves allow us to determine the effective correlation time of electron flips under our experimental conditions. The dependence of the DNP signal enhancement on electron spin concentration shows a maximum near 80 mM. Although no significant difference in the absolute DNP enhancements for triradical (DOTOPA-TEMPO) and biradical (TOTAPOL) dopants was found, the triradical produced greater DNP build-up rates, which are advantageous for DNP experiments. Additionally the feasibility of structural measurements on 13C-labeled biomolecules was demonstrated with a two-dimensional 13C-13C exchange spectrum of selectively 13C-labeled β-amyloid fibrils.

  11. 13C CPMAS NMR studies and DFT calculations of triterpene xylosides isolated from Actaea racemosa

    NASA Astrophysics Data System (ADS)

    Jamróz, Marta K.; Paradowska, Katarzyna; Gliński, Jan A.; Wawer, Iwona

    2011-05-01

    13C CPMAS NMR spectra of four triterpene glycosides: cimigenol xyloside ( 1), 26-deoxyactein ( 2), cimicifugoside H-1 ( 3) and 24-acethylhydroshengmanol xyloside ( 4) were recorded and analyzed to characterize their solid-state structure. Experimental data were supported by theoretical calculations of NMR shielding constants with the GIAO/6-31G**-su1 approach. A number of methods for the conformational search and a number of functionals for the DFT calculations were applied to ( 1). The best method was proven to be MMFF or MMFFAQ for the conformational search and the PBE1PBE functional for the DFT calculations. Extra calculations simulating C16 dbnd O⋯HOH hydrogen bond yield the isotropic shielding closer to the experimental solid-state value. For all the compounds CP kinetics parameters were calculated using either the I-S or the I-I*-S model. The analysis of CP kinetics data for methyl groups revealed differences in the T2 time constant for two methyl groups (C29 and C30) linked at C4.

  12. Identification and quantitative determination of lignans in Cedrus atlantica resins using 13C NMR spectroscopy.

    PubMed

    Nam, Anne-Marie; Paoli, Mathieu; Castola, Vincent; Casanova, Joseph; Bighelli, Ange

    2011-03-01

    Identification and quantitative determination of individual components of resin collected on the trunk of 28 Cedrus atlantica trees, grown in Corsica, has been carried out using 13C NMR spectroscopy. Eight resin acids bearing either the pimarane or abietane skeleton, two monoterpene hydrocarbons and four oxygenated neutral diterpenes have been identified, as well as three lignans, scarcely found in resins. Three groups could be distinguished within the 28 resin samples. The nine samples of Group I had their composition dominated by diterpene acids (33.7-45.8%), with abietic acid (6.2-18.7%) and isopimaric acid (5.1-12.6%) being the major components. The four samples of Group II contained resin acids (main components) and lignans in moderate amounts (up to 10.3%). Conversely, lignans (38.8-63.8%) were by far the major components of the 15 samples of Group III. Depending on the sample, the major component was pinoresinol (18.1-38.9%), lariciresinol (17.2-33.7%) or lariciresinol 9'-acetate (16.9-29.1%). Finally, due to the high biological interest in lignans, a rapid procedure, based on 1H NMR spectroscopy, was developed for quantification of lignans in resins of C. atlantica.

  13. Triple resonance experiments for aligned sample solid-state NMR of 13C and 15N labeled proteins

    PubMed Central

    Sinha, Neeraj; Grant, Christopher V.; Park, Sang Ho; Brown, Jonathan Miles; Opella, Stanley J.

    2013-01-01

    Initial steps in the development of a suite of triple-resonance 1H/13C/15N solid-state NMR experiments applicable to aligned samples of 13C and 15N labeled proteins are described. The experiments take advantage of the opportunities for 13C detection without the need for homonuclear 13C/13C decoupling presented by samples with two different patterns of isotopic labeling. In one type of sample, the proteins are ~20% randomly labeled with 13C in all backbone and side chain carbon sites and ~100% uniformly 15N labeled in all nitrogen sites; in the second type of sample, the peptides and proteins are 13C labeled at only the α-carbon and 15N labeled at the amide nitrogen of a few residues. The requirement for homonuclear 13C/13C decoupling while detecting 13C signals is avoided in the first case because of the low probability of any two 13C nuclei being bonded to each other; in the second case, the labeled 13Cα sites are separated by at least three bonds in the polypeptide chain. The experiments enable the measurement of the 13C chemical shift and 1H–13C and 15N–13C heteronuclear dipolar coupling frequencies associated with the 13Cα and 13C′ backbone sites, which provide orientation constraints complementary to those derived from the 15N labeled amide backbone sites. 13C/13C spin-exchange experiments identify proximate carbon sites. The ability to measure 13C–15N dipolar coupling frequencies and correlate 13C and 15N resonances provides a mechanism for making backbone resonance assignments. Three-dimensional combinations of these experiments ensure that the resolution, assignment, and measurement of orientationally dependent frequencies can be extended to larger proteins. Moreover, measurements of the 13C chemical shift and 1H–13C heteronuclear dipolar coupling frequencies for nearly all side chain sites enable the complete three-dimensional structures of proteins to be determined with this approach. PMID:17293139

  14. Chain-Folding Structures of a Semi-crystalline Polymer in Bulk and Single Crystals Elucidated by 13C-13C Double Quantum NMR

    NASA Astrophysics Data System (ADS)

    Hong, You-Lee; Miyoshi, Toshikazu

    2014-03-01

    Semi-crystalline polymers are crystallized as folded chains in thin lamellae of ca. 5-20 nm from random coils in the melt and solution states. However, understanding of detailed chain-folding structure and crystallization mechanism are still challenging issue due to various experimental limitations. We recently developed a new strategy using 13C-13C double-quantum (DQ) NMR with selectively 13C isotope labeled isotactic poly(1-butene) form I to investigate chain-trajectory in solution and melt grown crystals at various Tcs. This new method can determine the re-entrance sites, the successive folding number (n) , and the fractions (F) of chain-folding in a wide Tc range. In melt grown crystals at Tc = 95 °C, a comparison of experimental and simulated DQ efficiency determined that the polymer chains alternatively change chain-folding directions and the stems tightly pack via intramolecular interactions, and the fraction (F) of adjacent re-entry structure ranges from 70% at n = 4 to 100% at mixed structures of n = 1 and 2. Furthermore, DQ efficiency is independent of Tc in bulk crystals. This means chain-folding do not change in a wide Tcs. DMR-1105829.

  15. Structural Characterization of Humic Materials Using ^13C NMR Techniques: A Comparison of Solution- and Solid-State Methods

    NASA Astrophysics Data System (ADS)

    Clewett, Catherine; Alam, Todd; Osantowski, Eric; Pullin, Michael

    2011-10-01

    The analysis of the carbon type distribution and chemical structure of natural organic matter (NOM) by ^13C NMR spectroscopy is an important technique for understanding its origins and reactivity. While prior work has used solution-state NMR techniques, solid-state NMR has the potential to provide this information using less instrument time and sample manipulation, while providing an array of advanced filtering techniques. Analyses of four isolated humic materials with ^13C solid-state magic angle spinning (MAS) NMR techniques are described, including three commercially available samples and one fulvic acid sample isolated from the Rio Grande in New Mexico. This study demonstrates the utility of solid-state ^13C NMR for aquatic NOM structural characterization, comparing these results to the existing solution-state determinations. The solid-state ^13C MAS NMR results are used to determine % carbon distribution, estimates of elemental composition (%C, %H, %(O+N)), aromatic fraction (fa), nonprotonated aromatic fraction (faN), an estimate of aromatic cluster size, and ratio of sp^2 to sp^3 carbons. A Gaussian deconvolution method is introduced that allows for a detailed analysis of carbon type.

  16. DFT calculations of 1H and 13C NMR chemical shifts in transition metal hydrides.

    PubMed

    del Rosal, I; Maron, L; Poteau, R; Jolibois, F

    2008-08-14

    Transition metal hydrides are of great interest in chemistry because of their reactivity and their potential use as catalysts for hydrogenation. Among other available techniques, structural properties in transition metal (TM) complexes are often probed by NMR spectroscopy. In this paper we will show that it is possible to establish a viable methodological strategy in the context of density functional theory, that allows the determination of 1H NMR chemical shifts of hydride ligands attached to transition metal atoms in mononuclear systems and clusters with good accuracy with respect to experiment. 13C chemical shifts have also been considered in some cases. We have studied mononuclear ruthenium complexes such as Ru(L)(H)(dppm)2 with L = H or Cl, cationic complex [Ru(H)(H2O)(dppm)2]+ and Ru(H)2(dppm)(PPh3)2, in which hydride ligands are characterized by a negative 1H NMR chemical shift. For these complexes all calculations are in relatively good agreement compared to experimental data with errors not exceeding 20% except for the hydrogen atom in Ru(H)2(dppm)(PPh3)2. For this last complex, the relative error increases to 30%, probably owing to the necessity to take into account dynamical effects of phenyl groups. Carbonyl ligands are often encountered in coordination chemistry. Specific issues arise when calculating 1H or 13C NMR chemical shifts in TM carbonyl complexes. Indeed, while errors of 10 to 20% with respect to experiment are often considered good in the framework of density functional theory, this difference in the case of mononuclear carbonyl complexes culminates to 80%: results obtained with all-electron calculations are overall in very satisfactory agreement with experiment, the error in this case does not exceed 11% contrary to effective core potentials (ECPs) calculations which yield errors always larger than 20%. We conclude that for carbonyl groups the use of ECPs is not recommended, although their use could save time for very large systems, for

  17. DFT calculations of 1H and 13C NMR chemical shifts in transition metal hydrides.

    PubMed

    del Rosal, I; Maron, L; Poteau, R; Jolibois, F

    2008-08-14

    Transition metal hydrides are of great interest in chemistry because of their reactivity and their potential use as catalysts for hydrogenation. Among other available techniques, structural properties in transition metal (TM) complexes are often probed by NMR spectroscopy. In this paper we will show that it is possible to establish a viable methodological strategy in the context of density functional theory, that allows the determination of 1H NMR chemical shifts of hydride ligands attached to transition metal atoms in mononuclear systems and clusters with good accuracy with respect to experiment. 13C chemical shifts have also been considered in some cases. We have studied mononuclear ruthenium complexes such as Ru(L)(H)(dppm)2 with L = H or Cl, cationic complex [Ru(H)(H2O)(dppm)2]+ and Ru(H)2(dppm)(PPh3)2, in which hydride ligands are characterized by a negative 1H NMR chemical shift. For these complexes all calculations are in relatively good agreement compared to experimental data with errors not exceeding 20% except for the hydrogen atom in Ru(H)2(dppm)(PPh3)2. For this last complex, the relative error increases to 30%, probably owing to the necessity to take into account dynamical effects of phenyl groups. Carbonyl ligands are often encountered in coordination chemistry. Specific issues arise when calculating 1H or 13C NMR chemical shifts in TM carbonyl complexes. Indeed, while errors of 10 to 20% with respect to experiment are often considered good in the framework of density functional theory, this difference in the case of mononuclear carbonyl complexes culminates to 80%: results obtained with all-electron calculations are overall in very satisfactory agreement with experiment, the error in this case does not exceed 11% contrary to effective core potentials (ECPs) calculations which yield errors always larger than 20%. We conclude that for carbonyl groups the use of ECPs is not recommended, although their use could save time for very large systems, for

  18. Characterization of a Mixture of CO2 Adsorption Products in Hyperbranched Aminosilica Adsorbents by (13)C Solid-State NMR.

    PubMed

    Moore, Jeremy K; Sakwa-Novak, Miles A; Chaikittisilp, Watcharop; Mehta, Anil K; Conradi, Mark S; Jones, Christopher W; Hayes, Sophia E

    2015-11-17

    Hyperbranched amine polymers (HAS) grown from the mesoporous silica SBA-15 (hereafter "SBA-15-HAS") exhibit large capacities for CO2 adsorption. We have used static in situ and magic-angle spinning (MAS) ex situ (13)C nuclear magnetic resonance (NMR) to examine the adsorption of CO2 by SBA-15-HAS. (13)C NMR distinguishes the signal of gas-phase (13)CO2 from that of the chemisorbed species. HAS polymers possess primary, secondary, and tertiary amines, leading to multiple chemisorption reaction outcomes, including carbamate (RnNCOO(-)), carbamic acid (RnNCOOH), and bicarbonate (HCO3(-)) moieties. Carbamates and bicarbonate fall within a small (13)C chemical shift range (162-166 ppm), and a mixture was observed including carbamic acid and carbamate, the former disappearing upon evacuation of the sample. By examining the (13)C-(14)N dipolar coupling through low-field (B0 = 3 T) (13)C{(1)H} cross-polarization MAS NMR, carbamate is confirmed through splitting of the (13)C resonance. A third species that is either bicarbonate or a second carbamate is evident from bimodal T2 decay times of the ∼163 ppm peak, indicating the presence of two species comprising that single resonance. The mixture of products suggests that (1) the presence of amines and water leads to bicarbonate being present and/or (2) the multiple types of amine sites in HAS permit formation of chemically distinct carbamates.

  19. Conditions for (13)C NMR detection of 2-hydroxyglutarate in tissue extracts from isocitrate dehydrogenase-mutated gliomas.

    PubMed

    Pichumani, Kumar; Mashimo, Tomoyuki; Baek, Hyeon-Man; Ratnakar, James; Mickey, Bruce; DeBerardinis, Ralph J; Maher, Elizabeth A; Bachoo, Robert M; Malloy, Craig R; Kovacs, Zoltan

    2015-07-15

    (13)C NMR (nuclear magnetic resonance) spectroscopy of extracts from patient tumor samples provides rich information about metabolism. However, in isocitrate dehydrogenase (IDH)-mutant gliomas, (13)C labeling is obscured in oncometabolite 2-hydroxyglutaric acid (2 HG) by glutamate and glutamine, prompting development of a simple method to resolve the metabolites. J-coupled multiplets in 2 HG were similar to glutamate and glutamine and could be clearly resolved at pH 6. A cryogenically cooled (13)C probe, but not J-resolved heteronuclear single quantum coherence spectroscopy, significantly improved detection of 2 HG. These methods enable the monitoring of (13)C-(13)C spin-spin couplings in 2 HG expressing IDH-mutant gliomas.

  20. Metabolic characterization of Lactococcus lactis deficient in lactate dehydrogenase using in vivo 13C-NMR.

    PubMed

    Neves, A R; Ramos, A; Shearman, C; Gasson, M J; Almeida, J S; Santos, H

    2000-06-01

    The metabolism of glucose by nongrowing cells of Lactococcus lactis strain FI7851, constructed from the wild-type L. lactis strain MG1363 by disruption of the lactate dehydrogenase (ldh) gene [Gasson, M.J., Benson, K., Swindel, S. & Griffin, H. (1996) Lait 76, 33-40] was studied in a noninvasive manner by 13C-NMR. The kinetics of the build-up and consumption of the pools of intracellular intermediates mannitol 1-phosphate, fructose 1,6-bisphosphate, 3-phosphoglycerate, and phosphoenolpyruvate as well as the utilization of [1-13C]glucose and formation of products (lactate, acetate, mannitol, ethanol, acetoin, 2,3-butanediol) were monitored in vivo with a time resolution of 30 s. The metabolism of glucose by the parental wild-type strain was also examined for comparison. A clear shift from typical homolactic fermentation (parental strain) to a mixed acid fermentation (lactate dehdydrogenase deficient; LDHd strain) was observed. Furthermore, high levels of mannitol were transiently produced and metabolized once glucose was depleted. Mannitol 1-phosphate accumulated intracellularly up to 76 mM concentration. Mannitol was formed from fructose 6-phosphate by the combined action of mannitol-1-phosphate dehydrogenase and phosphatase. The results show that the formation of mannitol 1-phosphate by the LDHd strain during glucose catabolism is a consequence of impairment in NADH oxidation caused by a highly reduced LDH activity, the transient production of mannitol 1-phosphate serving as a regeneration pathway for NAD+ regeneration. Oxygen availability caused a drastic change in the pattern of intermediates and end-products, reinforcing the key-role of the fulfilment of the redox balance. The flux control coefficients for the step catalysed by mannitol-1-phosphate dehydrogenase were calculated and the implications in the design of metabolic engineering strategies are discussed.

  1. Characterization of Acetate and Pyruvate Metabolism in Suspension Cultures of Zea mays by 13C NMR Spectroscopy

    PubMed Central

    Ashworth, Dennis J.; Lee, Rino Y.; Adams, Douglas O.

    1987-01-01

    Carbon-13 nuclear magnetic resonance (NMR) spectroscopy has been applied to the direct observation of acetate and pyruvate metabolism in suspension cultures of Zea mays (var Black Mexican Sweet). Growth of the corn cells in the presence of 2 millimolar [2-13C]acetate resulted in a rapid uptake of the substrate from the medium and initial labeling (0-4 hours) of primarily the intracellular glutamate and malate pools. Further metabolism of these intermediates resulted in labeling of glutamine, aspartate, and alanine. With [1-13C]acetate as the substrate very little incorporation into intermediary metabolites was observed in the 13C NMR spectra due to loss of the label as 13CO2. Uptake of [3-13C]pyruvate by the cells was considerably slower than with [2-13C]acetate; however, the labelling patterns were similar with the exception of increased [3-13C] alanine generation with pyruvate as the substrate. Growth of the cells for up to 96 hours with 2 millimolar [3-13C]pyruvate ultimately resulted in labeling of valine, leucine, isoleucine, threonine, and the polyamine putrescine. PMID:16665721

  2. Dynamic nuclear polarization-enhanced 1H–13C double resonance NMR in static samples below 20 K

    PubMed Central

    Potapov, Alexey; Thurber, Kent R.; Yau, Wai-Ming; Tycko, Robert

    2012-01-01

    We demonstrate the feasibility of one-dimensional and two-dimensional 1H–13C double resonance NMR experiments with dynamic nuclear polarization (DNP) at 9.4 T and temperatures below 20 K, including both 1H–13C cross-polarization and 1H decoupling, and discuss the effects of polarizing agent type, polarizing agent concentration, temperature, and solvent deuteration. We describe a two-channel low-temperature DNP/NMR probe, capable of carrying the radio-frequency power load required for 1H–13C cross-polarization and high-power proton decoupling. Experiments at 8 K and 16 K reveal a significant T2 relaxation of 13C, induced by electron spin flips. Carr–Purcell experiments and numerical simulations of Carr–Purcell dephasing curves allow us to determine the effective correlation time of electron flips under our experimental conditions. The dependence of the DNP signal enhancement on electron spin concentration shows a maximum near 80 mM. Although no significant difference in the absolute DNP enhancements for triradical (DOTOPA-TEMPO) and biradical (TOTAPOL) dopants was found, the triradical produced greater DNP build-up rates, which are advantageous for DNP experiments. Additionally the feasibility of structural measurements on 13C-labeled biomolecules was demonstrated with a two-dimensional 13C–13C exchange spectrum of selectively 13C-labeled β-amyloid fibrils. PMID:22743540

  3. Sparse (13)C labelling for solid-state NMR studies of P. pastoris expressed eukaryotic seven-transmembrane proteins.

    PubMed

    Liu, Jing; Liu, Chang; Fan, Ying; Munro, Rachel A; Ladizhansky, Vladimir; Brown, Leonid S; Wang, Shenlin

    2016-05-01

    We demonstrate a novel sparse (13)C labelling approach for methylotrophic yeast P. pastoris expression system, towards solid-state NMR studies of eukaryotic membrane proteins. The labelling scheme was achieved by co-utilizing natural abundance methanol and specifically (13)C labelled glycerol as carbon sources in the expression medium. This strategy improves the spectral resolution by 1.5 fold, displays site-specific labelling patterns, and has advantages for collecting long-range distance restraints for structure determination of large eukaryotic membrane proteins by solid-state NMR.

  4. Thermal maturity of type II kerogen from the New Albany Shale assessed by 13C CP/MAS NMR.

    PubMed

    Werner-Zwanziger, Ulrike; Lis, Grzegorz; Mastalerz, Maria; Schimmelmann, Arndt

    2005-01-01

    Thermal maturity of oil and gas source rocks is typically quantified in terms of vitrinite reflectance, which is based on optical properties of terrestrial woody remains. This study evaluates 13C CP/MAS NMR parameters in kerogen (i.e., the insoluble fraction of organic matter in sediments and sedimentary rocks) as proxies for thermal maturity in marine-derived source rocks where terrestrially derived vitrinite is often absent or sparse. In a suite of samples from the New Albany Shale (Middle Devonian to the Early Mississippian, Illinois Basin) the abundance of aromatic carbon in kerogen determined by 13C CP/MAS NMR correlates linearly well with vitrinite reflectance.

  5. Solid-state 13C NMR study of na-cellulose complexes.

    PubMed

    Porro, Fabrizio; Bédué, Olivier; Chanzy, Henri; Heux, Laurent

    2007-08-01

    The interaction of microcrystalline cellulose from cotton and aqueous sodium hydroxide was investigated by 13C NMR solid-state spectroscopy as a function of temperature and sodium hydroxide concentration. When the concentration of NaOH was increased, the initial cellulose spectrum was replaced successively by that of Na-cellulose I followed by that of Na-cellulose II. In Na-cellulose I, each carbon atom occurred as a singlet, thus implying that one glucosyl moiety was the independent magnetic residue in the structure of this allomorph. In addition, the occurrence of the C6 near 62 ppm is an indication of a gt conformation for the hydroxymethyl group of Na-cellulose I. In Na-cellulose II, the analysis of the resonances of C1 and C6 points toward a structure based on a cellotriosyl moiety as the independent magnetic residue, in agreement with the established X-ray analysis that has shown that for this allomorph, the fiber repeat was also that of a cellotriosyl residue. For Na-cellulose II, the occurrence of the C6 in the 60 ppm region indicates an overall gg conformation for the hydroxymethyl groups. A comparison of the spectra recorded at 268 K and at room temperature confirms the stronger interaction of NaOH with cellulose when the temperature is lowered. In the Q region, corresponding to NaOH concentrations of around 9% and temperatures below 277 K, most of the sample was dissolved and no specific solid-state 13C NMR spectrum could be recorded, except for that of a small fraction of undissolved cellulose I. The same experiment run on a wood pulp sample leads to a new spectrum, with spectral characteristics different from those of Na-cellulose I and Na-cellulose II. This new spectrum is assigned to the Q phase, which appears to result from topological constraints that are present in whole wood pulp fibers but not in microcrystalline cellulose. A spectrum recorded for samples in the Na-cellulose III conditions resembled that of Na-cellulose II but of lower

  6. 13C and 113Cd NMR studies of the chelation of metal ions by the calcium binding protein parvalbumin.

    PubMed

    Bjornson, M E; Corson, D C; Sykes, B D

    1985-10-01

    13C NMR spectra are presented for the calcium binding protein parvalbumin (pI 4.25) from carp muscle in several different metal bound forms: with Ca2+ in both the CD and EF calcium binding sites, with Cd2+ in both sites, with 113Cd2+ in both sites, and with 113Cd2+ in the CD site and Lu3+ in the EF site. The different metals differentially shift the 13C NMR resonances of the protein ligands involved in chelation of the metal ion. In addition, direct 13C-113Cd spin-spin coupling is observed which allows the assignment of protein carbonyl and carboxyl 13C NMR resonances to ligands directly interacting with the metal ions in the CD and EF binding sites. The displacement of 113Cd2+ from the EF site by Lu3+ further allows these resonances to be assigned to the CD or EF site. The occupancy of the two sites in the two cadmium species and in the mixed Cd2+/Lu3+ species is verified by 113Cd NMR. The resolution in these 113Cd NMR spectra is sufficient to demonstrate direct interaction between the two metal binding sites.

  7. Discovering [superscript 13]C NMR, [superscript 1]H NMR, and IR Spectroscopy in the General Chemistry Laboratory through a Sequence of Guided-Inquiry Exercises

    ERIC Educational Resources Information Center

    Iler, H. Darrell; Justice, David; Brauer, Shari; Landis, Amanda

    2012-01-01

    This sequence of three guided-inquiry labs is designed for a second-semester general chemistry course and challenges students to discover basic theoretical principles associated with [superscript 13]C NMR, [superscript 1]H NMR, and IR spectroscopy. Students learn to identify and explain basic concepts of magnetic resonance and vibrational…

  8. Spectrally edited 2D 13Csbnd 13C NMR spectra without diagonal ridge for characterizing 13C-enriched low-temperature carbon materials

    NASA Astrophysics Data System (ADS)

    Johnson, Robert L.; Anderson, Jason M.; Shanks, Brent H.; Fang, Xiaowen; Hong, Mei; Schmidt-Rohr, Klaus

    2013-09-01

    Two robust combinations of spectral editing techniques with 2D 13Csbnd 13C NMR have been developed for characterizing the aromatic components of 13C-enriched low-temperature carbon materials. One method (exchange with protonated and nonprotonated spectral editing, EXPANSE) selects cross peaks of protonated and nearby nonprotonated carbons, while the other technique, dipolar-dephased double-quantum/single-quantum (DQ/SQ) NMR, selects signals of bonded nonprotonated carbons. Both spectra are free of a diagonal ridge, which has many advantages: Cross peaks on the diagonal or of small intensity can be detected, and residual spinning sidebands or truncation artifacts associated with the diagonal ridge are avoided. In the DQ/SQ experiment, dipolar dephasing of the double-quantum coherence removes protonated-carbon signals; this approach also eliminates the need for high-power proton decoupling. The initial magnetization is generated with minimal fluctuation by combining direct polarization, cross polarization, and equilibration by 13C spin diffusion. The dipolar dephased DQ/SQ spectrum shows signals from all linkages between aromatic rings, including a distinctive peak from polycondensed aromatics. In EXPANSE NMR, signals of protonated carbons are selected in the first spectral dimension by short cross polarization combined with dipolar dephasing difference. This removes ambiguities of peak assignment to overlapping signals of nonprotonated and protonated aromatic carbons, e.g. near 125 ppm. Spin diffusion is enhanced by dipolar-assisted rotational resonance. Before detection, Csbnd H dipolar dephasing by gated decoupling is applied, which selects signals of nonprotonated carbons. Thus, only cross peaks due to magnetization originating from protonated C and ending on nearby nonprotonated C are retained. Combined with the chemical shifts deduced from the cross-peak position, this double spectral editing defines the bonding environment of aromatic, COO, and Cdbnd O carbons

  9. 500-fold enhancement of in situ (13)C liquid state NMR using gyrotron-driven temperature-jump DNP.

    PubMed

    Yoon, Dongyoung; Soundararajan, Murari; Caspers, Christian; Braunmueller, Falk; Genoud, Jérémy; Alberti, Stefano; Ansermet, Jean-Philippe

    2016-09-01

    A 550-fold increase in the liquid state (13)C NMR signal of a 50μL sample was obtained by first hyperpolarizing the sample at 20K using a gyrotron (260GHz), then, switching its frequency in order to apply 100W for 1.5s so as to melt the sample, finally, turning off the gyrotron to acquire the (13)C NMR signal. The sample stays in its NMR resonator, so the sequence can be repeated with rapid cooling as the entire cryostat stays cold. DNP and thawing of the sample are performed only by the switchable and tunable gyrotron without external devices. Rapid transition from DNP to thawing in one second time scale was necessary especially in order to enhance liquid (1)H NMR signal. PMID:27490302

  10. 500-fold enhancement of in situ 13C liquid state NMR using gyrotron-driven temperature-jump DNP

    NASA Astrophysics Data System (ADS)

    Yoon, Dongyoung; Soundararajan, Murari; Caspers, Christian; Braunmueller, Falk; Genoud, Jérémy; Alberti, Stefano; Ansermet, Jean-Philippe

    2016-09-01

    A 550-fold increase in the liquid state 13C NMR signal of a 50 μL sample was obtained by first hyperpolarizing the sample at 20 K using a gyrotron (260 GHz), then, switching its frequency in order to apply 100 W for 1.5 s so as to melt the sample, finally, turning off the gyrotron to acquire the 13C NMR signal. The sample stays in its NMR resonator, so the sequence can be repeated with rapid cooling as the entire cryostat stays cold. DNP and thawing of the sample are performed only by the switchable and tunable gyrotron without external devices. Rapid transition from DNP to thawing in one second time scale was necessary especially in order to enhance liquid 1H NMR signal.

  11. 1H and 13C NMR assignments of new methoxylated furanoflavonoids from Lonchocarpus araripensis.

    PubMed

    Lima, Almi F; Mileo, Paulo Graziane M; Andrade-Neto, Manoel; Braz-Filho, Raimundo; Silveira, Edilberto R; Pessoa, Otília Deusdênia L

    2009-02-01

    Two new polymethoxylated flavonoids, 2',5',6'-trimethoxy-[2'',3'' : 3',4']furano dihydrochalcone and 2,4',4,5-tetramethoxy-[2'',3'' : 6,7]-furanodihydroaurone, were isolated from the root barks of Lonchocarpus araripensis, along with the known compounds 3,4,5,6-tetramethoxy-[2'',3'' : 7,8]-furanoflavan, 3,6-dimethoxy-1'',1''-dimethylcromene-[2'',3'' : 7,8]-flavone, 3',4'-methylenodioxy-5,6-dimethoxy-[2'',3'' : 7,8]-furanoflavone, 3,5,6-trimethoxy-[2'',3'' : 7,8]-furanoflavanone, 3,5,6-trimethoxy-[2'',3'' : 7,8]-furanoflavone, and 6alpha-hydroxy-medicarpin. The complete (1)H and (13)C NMR assignments of the new furan flavonoids were performed using 1D and 2D pulse sequences, including COSY, HSQC, and HMBC experiments, and comparison with spectral data for analog compounds from the literature, particularly for the new furanodihydroaurone because of several inconsistencies on the carbonyl chemical shifts from the literature. PMID:18932264

  12. (13)C-NMR-Based Metabolomic Profiling of Typical Asian Soy Sauces.

    PubMed

    Kamal, Ghulam Mustafa; Yuan, Bin; Hussain, Abdullah Ijaz; Wang, Jie; Jiang, Bin; Zhang, Xu; Liu, Maili

    2016-01-01

    It has been a strong consumer interest to choose high quality food products with clear information about their origin and composition. In the present study, a total of 22 Asian soy sauce samples have been analyzed in terms of (13)C-NMR spectroscopy. Spectral data were analyzed by multivariate statistical methods in order to find out the important metabolites causing the discrimination among typical soy sauces from different Asian regions. It was found that significantly higher concentrations of glutamate in Chinese red cooking (CR) soy sauce may be the result of the manual addition of monosodium glutamate (MSG) in the final soy sauce product. Whereas lower concentrations of amino acids, like leucine, isoleucine and valine, observed in CR indicate the different fermentation period used in production of CR soy sauce, on the other hand, the concentration of some fermentation cycle metabolites, such as acetate and sucrose, can be divided into two groups. The concentrations of these fermentation cycle metabolites were lower in CR and Singapore Kikkoman (SK), whereas much higher in Japanese shoyu (JS) and Taiwan (China) light (TL), which depict the influence of climatic conditions. Therefore, the results of our study directly indicate the influences of traditional ways of fermentation, climatic conditions and the selection of raw materials and can be helpful for consumers to choose their desired soy sauce products, as well as for researchers in further authentication studies about soy sauce. PMID:27598115

  13. 13C-NMR analysis of Aspergillus mutants disturbed in pyruvate metabolism.

    PubMed

    Dijkema, C; Visser, J

    1987-12-10

    The metabolic consequences of two defects in pyruvate metabolism of the hyphal fungus Aspergillus nidulans have been investigated by natural abundance 13C-NMR spectroscopy. A pyruvate dehydrogenase complex (pdh) mutant, grown on acetate, accumulates alanine upon starvation which is derived from mannitol reserves. The L-alanine level increases further upon incubation with the non-permissive substrate D-glucose. L-Glutamate is absent from these spectra as it is required both for the transamination of pyruvate and as a reaction on an impaired energy metabolism in such a pdh-deficient strain. A pyruvate carboxylase (pyc) mutant, grown upon acetate, only starts to accumulate alanine after a long incubation period with D-glucose, due to the long-lasting presence of phosphoenolpyruvate carboxykinase and malic enzyme, which are both induced by growth on acetate. When this strain is grown on D-fructose and L-glutamate, alanine also accumulates within 3 h upon transfer to D-glucose.

  14. Complete 1H and 13C NMR assignments of four new steroidal glycosides from a gorgonian coral Junceella juncea.

    PubMed

    Qi, Shuhua; Zhang, Si; Huang, Jianshe; Xiao, Zhihui; Wu, Jun; Li, Qingxin

    2005-03-01

    Four new cholest-type steroidal glycosides, junceellosides A-D, isolated from the EtOH/CH(2)Cl(2) extracts of the South China Sea gorgonian coral Junceella juncea, were identified. Complete assignments of the (1)H and (13)C NMR chemical shifts for these compounds were achieved by means of one- and two-dimensional NMR techniques, including (1)H-(1)H COSY, HSQC, HMBC and NOESY spectra.

  15. NMR studies of bent DNA using {sup 13}C-enriched samples

    SciTech Connect

    Zimmer, D.P.; Crothers, D.M.

    1994-12-01

    Bending of the DNA double helix can be brought about by introducing runs of adenines (A-tracts) in phase with the helical repeat of the DNA. The requirements for bending of DNA by A-tracts are that the length of the A-tract be greater than 3 base pairs and that the A-tracts must be in phase with the helical repeat (every 10 or 11 bp). Other factors, such as the number of adenines in the run, flanking sequences, and whether the A-tracts are phased with respect to the 5{prime}A or the 3{prime}A, have effects upon the degree of bending as assayed by electrophoretic mobility on native polyacrylamide gels. There are a number of models for bending A-tract DNA. The junction-bending model postulates that the structure of A-tracts is similar to the fiber diffraction structure of poly A, in which there is a significant degree of base pair tilt with respect to the helix axis. In this model, bending occurs at the junction between the A-tract and the B-form helix to allow favorable stacking interactions to occur. The bend of the helix could arise as a result of some other perturbation of B-form DNA by A-tracts, such as propeller twist; bending also could be due to a combination of factors. Our goal is to find the structural features of A-tracts responsible for bending of the helix by performing NMR on oligonucleotides containing A-tracts to obtain higher resolution structural data. One of the problems encountered in NMR structure determination of nucleic acids and other macromolecules is the assignment of resonances to nuclei. This procedure can be greatly facilitated through the use of {sup 13}C-enriched nucleic acid samples. We are developing a technique for the enzymatic synthesis of labeled DNA for NMR. The technique we are developing is similar to RNA labeling techniques already in use. The technique involves growth of methylotrophic bacteria on {sup 13}CH{sub 3}OH.

  16. Simple method for identification of skeletons of aporphine alkaloids from 13C NMR data using artificial neural networks.

    PubMed

    Rufino, Alessandra R; Brant, Antônio J C; Santos, João B O; Ferreira, Marcelo J P; Emerenciano, Vicente P

    2005-01-01

    This paper describes the use of artificial neural networks as a theoretical tool in the structural determination of alkaloids from (13)C NMR chemical shift data, aiming to identify skeletal types of those compounds. For that, 162 aporphine alkaloids belonging to 12 different skeletons were codified with their respective (13)C NMR chemical shifts. Each skeleton pertaining to aporphine alkaloid type was used as output, and the (13)C NMR chemical shifts were used as input data of the net. Analyzing the obtained results, one can then affirm the skeleton to which each one of these compounds belongs with high degree of confidence (over 97%). The relation between the correlation coefficient and the number of epochs and the architecture of net (3-layer MLP or 4-layer MLP) were analyzed, too. The analysis showed that the results predicted by the 3-layer MLP networks trained with a number of the epochs higher than 900 epochs are the best ones. The artificial neural nets were shown to be a simple and efficient tool to solve structural elucidation problems making use of (13)C NMR chemical shift data, even when a similarity between the searched skeletons occurs, offering fast and accurate results to identification of skeletons of organic compounds.

  17. 1H and 13C NMR characterization and secondary structure of the K2 polysaccharide of Klebsiella pneumoniae strain 52145.

    PubMed

    Corsaro, Maria Michela; De Castro, Cristina; Naldi, Teresa; Parrilli, Michelangelo; Tomás, Juan M; Regué, Miguel

    2005-09-26

    The complete (1)H and (13)C NMR characterization of the tetrasaccharide repeating unit from the K2 polysaccharide of Klebsiella pneumoniae strain 52145 is reported. [chemical structure] In addition a model for its secondary structure was suggested on the basis of dynamic and molecular calculations.

  18. Complete assignment of (1)H and (13)C NMR spectra of standard neo-iota-carrabiose oligosaccharides.

    PubMed

    Jouanneau, Diane; Boulenguer, Patrick; Mazoyer, Jacques; Helbert, William

    2010-02-26

    Standard Eucheuma denticulatum iota-carrageenan was degraded with the Alteromonas fortis iota-carrageenase. The most abundant products, the neo-iota-carratetraose and neo-iota-carrahexaose were purified by permeation gel chromatography, and their corresponding (1)H and (13)C NMR spectra were fully assigned. PMID:20038459

  19. Solid-state 13C NMR and molecular modeling studies of acetyl aleuritolic acid obtained from Croton cajucara Benth

    NASA Astrophysics Data System (ADS)

    da Silva San Gil, Rosane Aguiar; Albuquerque, Magaly Girão; de Alencastro, Ricardo Bicca; da Cunha Pinto, Angelo; do Espírito Santo Gomes, Fabiano; de Castro Dantas, Tereza Neuma; Maciel, Maria Aparecida Medeiros

    2008-08-01

    Solid-state 13C nuclear magnetic resonance ( 13C NMR) with magic-angle spinning (MAS) and with cross-polarization and magic-angle spinning (CP/MAS) spectra, and differential scanning calorimetry (DSC) techniques were used to obtain structural data from a sample of acetyl aleuritolic acid (AAA) extracted from the stem bark of Croton cajucara Benth. (Euphorbiaceae) and recrystallized from acetone. Since solid-state 13C NMR results suggested the presence of more than one molecule in the unitary cell for the AAA, DSC analysis and molecular modeling calculations were used to access this possibility. The absence of phase transition peaks in the DSC spectra and the dimeric models of AAA simulated using the semi-empirical PM3 method are in agreement with that proposal.

  20. Enzymatic 13C Labeling and Multidimensional NMR Analysis of Miltiradiene Synthesized by Bifunctional Diterpene Cyclase in Selaginella moellendorffii*

    PubMed Central

    Sugai, Yoshinori; Ueno, Yohei; Hayashi, Ken-ichiro; Oogami, Shingo; Toyomasu, Tomonobu; Matsumoto, Sadamu; Natsume, Masahiro; Nozaki, Hiroshi; Kawaide, Hiroshi

    2011-01-01

    Diterpenes show diverse chemical structures and various physiological roles. The diversity of diterpene is primarily established by diterpene cyclases that catalyze a cyclization reaction to form the carbon skeleton of cyclic diterpene. Diterpene cyclases are divided into two types, monofunctional and bifunctional cyclases. Bifunctional diterpene cyclases (BDTCs) are involved in hormone and defense compound biosyntheses in bryophytes and gymnosperms, respectively. The BDTCs catalyze the successive two-step type-B (protonation-initiated cyclization) and type-A (ionization-initiated cyclization) reactions of geranylgeranyl diphosphate (GGDP). We found that the genome of a lycophyte, Selaginella moellendorffii, contains six BDTC genes with the majority being uncharacterized. The cDNA from S. moellendorffii encoding a BDTC-like enzyme, miltiradiene synthase (SmMDS), was cloned. The recombinant SmMDS converted GGDP to a diterpene hydrocarbon product with a molecular mass of 272 Da. Mutation in the type-B active motif of SmMDS abolished the cyclase activity, whereas (+)-copalyl diphosphate, the reaction intermediate from the conversion of GGDP to the hydrocarbon product, rescued the cyclase activity of the mutant to form a diterpene hydrocarbon. Another mutant lacking type-A activity accumulated copalyl diphosphate as the reaction intermediate. When the diterpene hydrocarbon was enzymatically synthesized from [U-13C6]mevalonate, all carbons were labeled with 13C stable isotope (>99%). The fully 13C-labeled product was subjected to 13C-13C COSY NMR spectroscopic analyses. The direct carbon-carbon connectivities observed in the multidimensional NMR spectra demonstrated that the hydrocarbon product by SmMDS is miltiradiene, a putative biosynthetic precursor of tanshinone identified from the Chinese medicinal herb Salvia miltiorrhiza. Hence, SmMDS functions as a bifunctional miltiradiene synthase in S. moellendorffii. In this study, we demonstrate that one-dimensional and

  1. 13C NMR and isotopic (δ13C) investigations on modern vegetation samples: a tool to understand the soil organic matter degradation dynamics and preferences

    NASA Astrophysics Data System (ADS)

    Rakshit, Subhadeep; Sanyal, Prasanta; Vardhan Gaur, Harsh

    2015-04-01

    Soil organic carbon, one of the largest reservoirs of carbon, is a heterogeneous mixture of organic compounds with dominant contribution derived from decomposition of plants in various stages. Although general ideas about the processes and mechanisms of soil organic matter (SOM) degradation have been developed, a very few study has linked the SOM with its parent material. In this study we aim to generate reference data set of functional groups from modern vegetation samples (C3 and C4plants) to better understand the degradation dynamics and preferences. The carbon functional groups from modern vegetation samples (eight C3 and nine C4 plants collected from Mohanpur, Nadia, West Bengal, India) were examined by solid state 13C CPMAS NMR spectroscopy. Additionally, isotopic investigations (δ13C) has also been carried out on the modern vegetation samples to understand the relationship of bulk isotopic values to the concentration of functional groups. The major functional groups (alkyl C, O-alkyl C, aromatic C, carbonyl C and aldehyde/ketone) of modern vegetation samples form 16%, 65%, 5%, 14% and 1% respectively in C3 plants. Considerable differences has been observed for C4 plants with average values of alkyl C, O-alkyl C, aromatic C, carbonyl C and aldehyde/ketone are 8%, 83%, 3%, 5% and 1% respectively. The concentration of functional groups from the modern vegetational samples can be considered as reference scale to compare with the 13C NMR data derived from the different soil horizons to understand the SOM degradation dynamics. The δ13CV PDB values of modern vegetation samples plotted against the individual concentration of functional groups shows significant correlation in C4 plants, whereas a lack in correlation has been observed for C3 plants. We assume this difference in relationship of δ13CV PDB values with functional groups of C3 and C4plants can be due to the differences in photosynthesis pathways, the fractionation of CO2 and accumulation of the products

  2. Spectroscopic (FT-IR, (1)H, (13)C NMR and UV-vis) characterization and DFT studies of novel 8-((4-(methylthio)-2,5-diphenylfuran-3-yl)methoxy)quinoline.

    PubMed

    Diwaker; Chidan Kumar, C S; Kumar, Ashwani; Chandraju, Siddegowda

    2015-11-01

    In this study, computational calculations of a new quinoline derivative: 8-((4-(methylthio)-2,5-diphenylfuran-3-yl)methoxy)quinoline is carried out using ab initio methods. The geometry optimization as well as fundamental frequencies of the most stable configuration of the title compound is reported. A detailed study of Infrared spectrum, chemical shifts and electronic spectrum of the title compound is also presented. The Gauge-Invariant Atomic Orbital approach is used to calculate the proton and carbon chemical shifts of the title compound. The natural bond orbital analysis of the title compound is also reported in order to understand the stability of the molecule which arises from hyper conjugative interactions and charge delocalization. The theoretical electronic absorption spectrum is also reported using the time dependent density functional approach. The molecular structure along with vibrational frequencies as simulated for binding of iron with the title compound is also reported using ab initio methods. PMID:26079516

  3. Effects of low-temperature catalytic pretreatments on coal structure and reactivity in liquefaction. Final technical report, Volume 2 - hydrogenative and hydrothermal pretreatments and spectroscopic characterization using pyrolysis-GC-MS, CPMAS {sup 13}C NMR and FT-IR

    SciTech Connect

    Chunshan Song; Hatcher, P.G.; Saini, A.K.; Wenzel, K.A.

    1998-01-01

    It has been indicated by DOE COLIRN panel that low-temperature catalytic pretreatment is a promising approach to the development of an improved liquefaction process. This work is a fundamental study on effects of pretreatments on coal structure and reactivity in liquefaction. The main objectives of this project are to study the coal structural changes induced by low-temperature catalytic and thermal pretreatments by using spectroscopic techniques; and to clarify the pretreatment-induced changes in reactivity or convertibility of coals. As the second volume of the final report, here we summarize our work on spectroscopic characterization of four raw coals including two subbituminous coals and two bituminous coals, tetrahydrofuran (THF)-extracted but unreacted coals, the coals (THF-insoluble parts) that have been thermally pretreated. in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent, and the coals (THF-insoluble parts) that have been catalytically pretreated in the presence of a dispersed Mo sulfide catalyst in the absence of any solvents and in the presence of either a hydrogen-donor solvent or a non-donor solvent.

  4. Characterization of cerebral glutamine uptake from blood in the mouse brain: implications for metabolic modeling of 13C NMR data

    PubMed Central

    Bagga, Puneet; Behar, Kevin L; Mason, Graeme F; De Feyter, Henk M; Rothman, Douglas L; Patel, Anant B

    2014-01-01

    13C Nuclear Magnetic Resonance (NMR) studies of rodent and human brain using [1-13C]/[1,6-13C2]glucose as labeled substrate have consistently found a lower enrichment (∼25% to 30%) of glutamine-C4 compared with glutamate-C4 at isotopic steady state. The source of this isotope dilution has not been established experimentally but may potentially arise either from blood/brain exchange of glutamine or from metabolism of unlabeled substrates in astrocytes, where glutamine synthesis occurs. In this study, the contribution of the former was evaluated ex vivo using 1H-[13C]-NMR spectroscopy together with intravenous infusion of [U-13C5]glutamine for 3, 15, 30, and 60 minutes in mice. 13C labeling of brain glutamine was found to be saturated at plasma glutamine levels >1.0 mmol/L. Fitting a blood–astrocyte–neuron metabolic model to the 13C enrichment time courses of glutamate and glutamine yielded the value of glutamine influx, VGln(in), 0.036±0.002 μmol/g per minute for plasma glutamine of 1.8 mmol/L. For physiologic plasma glutamine level (∼0.6 mmol/L), VGln(in) would be ∼0.010 μmol/g per minute, which corresponds to ∼6% of the glutamine synthesis rate and rises to ∼11% for saturating blood glutamine concentrations. Thus, glutamine influx from blood contributes at most ∼20% to the dilution of astroglial glutamine-C4 consistently seen in metabolic studies using [1-13C]glucose. PMID:25074745

  5. Variable-temperature 13C solid-state NMR study of the molecular structure of honeybee wax and silk.

    PubMed

    Kameda, Tsunenori; Tamada, Yasushi

    2009-01-01

    To elucidate the native-state crystal structure of beeswax from the Japanese bee, Apis cerana japonica, we determined the relationship between temperature and the 13C solid-state nuclear magnetic resonance (NMR) chemical shift of methylene carbon of beeswax, with comparison to n-alkanes and polyethylene in the orthorhombic, monoclinic, or triclinic crystal form. Variable-temperature 13C solid-state NMR observations of n-alkanes and polyethylene revealed that the chemical shifts of methylene carbon in the orthorhombic crystal form increased linearly with increasing temperature, that of the triclinic form decreased, and that of the monoclinic form was unaltered. These relations were compared with results of variable-temperature 13C solid-state NMR observation of beeswax. Results clarified that the two crystal forms comprising the beeswax in the native state are orthorhombic and monoclinic. The variable-temperature 13C solid-state NMR observations were also applied to interpret the differential scanning calorimetry (DSC) curve of beeswax. They were used to clarify the structural changes of beeswax for widely various temperatures. For beeswax secreted by the Japanese bee, the transition from the orthorhombic form to the rotator phase occurred at 36 degrees C, that is from the crystalline to the intermediate state at 45 degrees C. Moreover, the variable-temperature 13C solid-state NMR spectrum of honeybee silk in the native state was observed. Results demonstrated that the secondary structures of honeybee silk proteins in the native state comprised coexisting alpha-helix and beta-sheet conformations and that the amount of alpha-helices was greater. The alpha-helix content of honeybee silk was compared with that of hornet silk produced by Vespa larvae.

  6. {sup 13}C-NMR study on the structure of isolated Sc{sub 2}@C{sub 84} metallofullerene

    SciTech Connect

    Yamamoto, Etsuji; Tansho, Masataka; Tomiyama, Tetsuo; Shinohara, Hisanori; Kawahara, Hironori; Kobayashi, Yuji

    1996-03-06

    Here we report the first {sup 13}C-NMR results on the metallofullerene, Sc{sub 2}@C{sub 84}, which determines an isomer cage structure for the metallofullerene. The Sc{sub 2}@C{sub 84} fullerene was separated and isolated from the various hollow fullerenes (C{sub 60}-C{sub 110}) and other scandium metallofullerenes by the multistage high-performance liquid chromatography (HPLC) method by using two complementary types of HPLC columns. The purity of Sc{sub 2}@C{sub 84} relative to other fullerenes was more than 99.9%. {sup 13}C-NMR measurements were made using a 600 MHz NMR (JEOL JNM-A600) at room temperature in CS{sub 2} solvent. 30 refs., 3 figs.

  7. Method for determining molar concentrations of metabolites in complex solutions from two-dimensional 1H-13C NMR spectra.

    PubMed

    Lewis, Ian A; Schommer, Seth C; Hodis, Brendan; Robb, Kate A; Tonelli, Marco; Westler, William M; Sussman, Michael R; Markley, John L

    2007-12-15

    One-dimensional (1D) (1)H nuclear magnetic resonance (NMR) spectroscopy is used extensively for high-throughput analysis of metabolites in biological fluids and tissue extracts. Typically, such spectra are treated as multivariate statistical objects rather than as collections of quantifiable metabolites. We report here a two-dimensional (2D) (1)H-(13)C NMR strategy (fast metabolite quantification, FMQ, by NMR) for identifying and quantifying the approximately 40 most abundant metabolites in biological samples. To validate this technique, we prepared mixtures of synthetic compounds and extracts from Arabidopsis thaliana, Saccharomyces cerevisiae, and Medicago sativa. We show that accurate (technical error 2.7%) molar concentrations can be determined in 12 min using our quantitative 2D (1)H-(13)C NMR strategy. In contrast, traditional 1D (1)H NMR analysis resulted in 16.2% technical error under nearly ideal conditions. We propose FMQ by NMR as a practical alternative to 1D (1)H NMR for metabolomics studies in which 50-mg (extract dry weight) samples can be obtained. PMID:17985927

  8. Method for determining molar concentrations of metabolites in complex solutions from two-dimensional 1H-13C NMR spectra.

    PubMed

    Lewis, Ian A; Schommer, Seth C; Hodis, Brendan; Robb, Kate A; Tonelli, Marco; Westler, William M; Sussman, Michael R; Markley, John L

    2007-12-15

    One-dimensional (1D) (1)H nuclear magnetic resonance (NMR) spectroscopy is used extensively for high-throughput analysis of metabolites in biological fluids and tissue extracts. Typically, such spectra are treated as multivariate statistical objects rather than as collections of quantifiable metabolites. We report here a two-dimensional (2D) (1)H-(13)C NMR strategy (fast metabolite quantification, FMQ, by NMR) for identifying and quantifying the approximately 40 most abundant metabolites in biological samples. To validate this technique, we prepared mixtures of synthetic compounds and extracts from Arabidopsis thaliana, Saccharomyces cerevisiae, and Medicago sativa. We show that accurate (technical error 2.7%) molar concentrations can be determined in 12 min using our quantitative 2D (1)H-(13)C NMR strategy. In contrast, traditional 1D (1)H NMR analysis resulted in 16.2% technical error under nearly ideal conditions. We propose FMQ by NMR as a practical alternative to 1D (1)H NMR for metabolomics studies in which 50-mg (extract dry weight) samples can be obtained.

  9. /sup 31/P NMR saturation-transfer and /sup 13/C NMR kinetic studies of glycolytic regulation during anaerobic and aerobic glycolysis

    SciTech Connect

    Campbell-Burk, S.L.; den Hollander, J.A.; Alger, J.R.; Shulman, R.G.

    1987-11-17

    /sup 31/P NMR saturation-transfer techniques have been employed in glucose-gown derepressed yeast to determine unidirectional fluxes in the upper part of the Embden-Meyerhof-Parnas pathway. The experiments were performed during anaerobic and aerobic glycolysis by saturating the ATP/sub ..gamma../ resonances and monitoring changes in the phosphomonoester signals from glucose 6-phosphate and fructose 1,6-bisphosphate. These experiments were supplemented with /sup 13/C NMR measurements of glucose utilization rates and /sup 13/C NMR label distribution studies. Combined with data obtained previously from radioisotope measurement, these /sup 31/P and /sup 13/C NMR kinetic studies allowed estimation of the net glycolytic flow in addition to relative flows through phosphofructokinase (PFK) and Fru-1,6-P/sub 2/ase during anaerobic and aerobic glycolysis. The /sup 31/P NMR saturation-transfer results are consistent with previous results obtained from measurements of metabolite levels, radioisotope data, and /sup 13/C NMR studies, providing additional support for in vivo measurement of the flows during glycolysis.

  10. Origin of the conformational modulation of the 13C NMR chemical shift of methoxy groups in aromatic natural compounds.

    PubMed

    Toušek, Jaromír; Straka, Michal; Sklenář, Vladimír; Marek, Radek

    2013-01-24

    The interpretation of nuclear magnetic resonance (NMR) parameters is essential to understanding experimental observations at the molecular and supramolecular levels and to designing new and more efficient molecular probes. In many aromatic natural compounds, unusual (13)C NMR chemical shifts have been reported for out-of-plane methoxy groups bonded to the aromatic ring (~62 ppm as compared to the typical value of ~56 ppm for an aromatic methoxy group). Here, we analyzed this phenomenon for a series of aromatic natural compounds using Density Functional Theory (DFT) calculations. First, we checked the methodology used to optimize the structure and calculate the NMR chemical shifts in aromatic compounds. The conformational effects of the methoxy group on the (13)C NMR chemical shift then were interpreted by the Natural Bond Orbital (NBO) and Natural Chemical Shift (NCS) approaches, and by excitation analysis of the chemical shifts, breaking down the total nuclear shielding tensor into the contributions from the different occupied orbitals and their magnetic interactions with virtual orbitals. We discovered that the atypical (13)C NMR chemical shifts observed are not directly related to a different conjugation of the lone pair of electrons of the methoxy oxygen with the aromatic ring, as has been suggested. Our analysis indicates that rotation of the methoxy group induces changes in the virtual molecular orbital space, which, in turn, correlate with the predominant part of the contribution of the paramagnetic deshielding connected with the magnetic interactions of the BD(CMet-H)→BD*(CMet-OMet) orbitals, resulting in the experimentally observed deshielding of the (13)C NMR resonance of the out-of-plane methoxy group.

  11. /sup 13/C NMR studies of porphobilinogen synthase: observation of intermediates bound to a 280,000-dalton protein

    SciTech Connect

    Jaffe, E.K.; Markham, G.D.

    1987-07-14

    /sup 13/C NMR has been used to observe the equilibrium complex of (4-/sup 13/C)-5-aminolevulinate ((4-/sup 13/C)ALA) bound to porphobilinogen (PBG) synthase (5-aminolevulinate dehydratase), a 280,000-dalton protein. (4-/sup 13/C)ALA (chemical shift = 205.9 ppm) forms (3,5-/sup 13/C)PBG (chemical shifts = 121.0 and 123.0 ppm). PBG prepared from a mixture of (4-/sup 13/C)ALA and (/sup 15/N)ALA was used to assign the 121.0 and 123.0 ppm resonances to C/sub 5/ and C/sub 3/, respectively. For the enzyme-bound equilibrium complex formed from holoenzyme and (4-/sup 13/C)ALA, two peaks of equal area with chemical shifts of 121.5 and 127.2 ppm are observed (line widths approx. 50 Hz), indicating that the predominant species is probably a distorted form of PBG. When excess free PBG is present, it is in slow exchange with bound PBG, indicating an exchange rate of < 10 s/sup -1/, which is consistent with the turnover rate of the enzyme. For the complex formed from (4-/sup 13/C)ALA and methyl methanethiosulfonate (MMTS) modified PBG synthase, which does not catalyze PBG formation, the predominant species is a Schiff base adduct (chemical shift = 166.5 ppm, line width approx. 50 Hz). Free ALA is in slow exchange with the Schiff base. Activation of the MMTS-modified enzyme-Schiff base complex with /sup 113/Cd and 2-mercaptoethanol results in the loss of the Schiff base signal and the appearance of bound PBG with the same chemical shifts as for the bound equilibrium complex with Zn(II) enzyme. Neither splitting nor broadening from /sup 113/Cd-/sup 13/C coupling was observed.

  12. DFT study of molecular structures and 13C NMR parameters of two fluorinated biphenyls and their η6-tricarbonylchromium complexes

    NASA Astrophysics Data System (ADS)

    Gryff-Keller, Adam; Szczeciński, Przemysław

    2015-07-01

    The molecular structures of 2,2‧-difluoro-6,6‧-dimethylbiphenyl, 4,5-difluoro-9,10-dihydrophenanthrene and of their η6-tricarbonylchromium complexes have been discussed in the light of the results of molecular energy calculations. Also the isotropic magnetic shielding constants and carbon-fluorine spin-spin coupling constants for these objects have been calculated and compared with the experimental values of 13C NMR chemical shifts and J constants. The calculational methods used were: DFT/BHandH/6-311++G(2d,p) and/or DFT/B3LYP/6-311++G(2d,p). It has been confirmed that experimental 13C NMR chemical shifts for η6-arene tricarbonylchromium complexes can be satisfactorily predicted using both methods, although the method exploiting BHandH functional is not able to reproduce the 13C NMR chemical shifts of Cr(CO)3 carbon atoms. On the other hand, this method provides the J(13C, 19F) values which are close to the experimental ones.

  13. {sup 13}C chemical shift anisotropies for carbonate ions in cement minerals and the use of {sup 13}C, {sup 27}Al and {sup 29}Si MAS NMR in studies of Portland cement including limestone additions

    SciTech Connect

    Sevelsted, Tine F.; Herfort, Duncan

    2013-10-15

    {sup 13}C isotropic chemical shifts and chemical shift anisotropy parameters have been determined for a number of inorganic carbonates relevant in cement chemistry from slow-speed {sup 13}C MAS or {sup 13}C({sup 1}H) CP/MAS NMR spectra (9.4 T or 14.1 T) for {sup 13}C in natural abundance. The variation in the {sup 13}C chemical shift parameters is relatively small, raising some doubts that different carbonate species in Portland cement-based materials may not be sufficiently resolved in {sup 13}C MAS NMR spectra. However, it is shown that by combining {sup 13}C MAS and {sup 13}C({sup 1}H) CP/MAS NMR carbonate anions in anhydrous and hydrated phases can be distinguished, thereby providing valuable information about the reactivity of limestone in cement blends. This is illustrated for three cement pastes prepared from an ordinary Portland cement, including 0, 16, and 25 wt.% limestone, and following the hydration for up to one year. For these blends {sup 29}Si MAS NMR reveals that the limestone filler accelerates the hydration for alite and also results in a smaller fraction of tetrahedrally coordinated Al incorporated in the C-S-H phase. The latter result is more clearly observed in {sup 27}Al MAS NMR spectra of the cement–limestone blends and suggests that dissolved aluminate species in the cement–limestone blends readily react with carbonate ions from the limestone filler, forming calcium monocarboaluminate hydrate. -- Highlights: •{sup 13}C chemical shift anisotropies for inorganic carbonates from {sup 13}C MAS NMR. •Narrow {sup 13}C NMR chemical shift range (163–171 ppm) for inorganic carbonates. •Anhydrous and hydrated carbonate species by {sup 13}C MAS and {sup 13}C({sup 1}H) CP/MAS NMR. •Limestone accelerates the hydration for alite in Portland – limestone cements. •Limestone reduces the amount of aluminium incorporated in the C-S-H phase.

  14. Near-silence of isothiocyanate carbon in (13)C NMR spectra: a case study of allyl isothiocyanate.

    PubMed

    Glaser, Rainer; Hillebrand, Roman; Wycoff, Wei; Camasta, Cory; Gates, Kent S

    2015-05-01

    (1)H and (13)C NMR spectra of allyl isothiocyanate (AITC) were measured, and the exchange dynamics were studied to explain the near-silence of the ITC carbon in (13)C NMR spectra. The dihedral angles α = ∠(C1-C2-C3-N4) and β = ∠(C2-C3-N4-C5) describe the conformational dynamics (conformation change), and the bond angles γ = ∠(C3-N4-C5) and ε = ∠(N4-C5-S6) dominate the molecular dynamics (conformer flexibility). The conformation space of AITC contains three minima, Cs-M1 and enantiomers M2 and M2'; the exchange between conformers is very fast, and conformational effects on (13)C chemical shifts are small (νM1 - νM2 < 3 ppm). Isotropic chemical shifts, ICS(γ), were determined for sp, sp(x), and sp(2) N-hybridization, and the γ dependencies of δ(N4) and δ(C5) are very large (10-33 ppm). Atom-centered density matrix propagation trajectories show that every conformer can access a large region of the potential energy surface AITC(γ,ε,...) with 120° < γ < 180° and 155° < ε < 180°. Because the extreme broadening of the (13)C NMR signal of the ITC carbon is caused by the structural flexibility of every conformer of AITC, the analysis provides a general explanation for the near-silence of the ITC carbon in (13)C NMR spectra of organic isothiocyanates.

  15. Variable angle spinning (VAS) NMR study of solvent effects in liquid crystalline solutions of 13C-iodomethane

    NASA Astrophysics Data System (ADS)

    Park, Gregory H. J.; Martin, Rachel W.; Sakellariou, Dimitris; Pines, Alexander; Shahkhatuni, Aleksan G.; Shahkhatuni, Astghik A.; Panosyan, Henry A.

    2004-11-01

    NMR spectra of 13C-iodomethane oriented in three different liquid crystalline solvents have been collected and analyzed under spinning at various angles with respect to the static magnetic field. For each sample the ratio of homonuclear ( 1H- 1H) to heteronuclear ( 13C- 1H) dipolar couplings, which is a function of the geometry of the solute molecule, does not change significantly with the scaling of the dipolar couplings due to spinning at different angles. This result implies that the 'apparent bond angle deviations' (Δ θa), previously calculated from thermotropic liquid crystals, arise from a solvent effect and are not an artifact from scaling the anisotropic interactions.

  16. 13C NMR spectra of 1,3-dipyridyl- and pyridylphenylthioureas. Chemical shift assignments and conformational implications

    NASA Astrophysics Data System (ADS)

    Sudha, L. V.; Sathyanarayana, D. N.; Manogaran, S.

    The 13C NMR spectra of a series of 1,3-dipyridyl- and pyridylphenylthioureas have been obtained. Complete analyses of the experimental spectra have provided the chemical shifts and coupling constants. The spectra of dipyridylthioureas over a temperature range showed important changes which could be attributed to an intramolecular conversion between the two equivalent E,Z and Z,E conformations. The coalescence temperature of the 13C signals leads to a Δ G* of ˜ 58.0 kJ mol -1 for the dynamic process involved. The results show that pyridylphenyl thioureas exist in a single conformation at ambient temperature.

  17. Complexation of oxygen ligands with dimeric rhodium(II) tetrakistrifluoroacetate in chloroform: 1H, 13C NMR and DFT studies

    NASA Astrophysics Data System (ADS)

    Głaszczka, Rafał; Jaźwiński, Jarosław

    2013-03-01

    The complexation of dimeric rhodium(II) tetrakistrifluoroacetylate with 25 ligands containing oxygen atoms: alcohols, ethers, ketones, aldehydes, carboxylic acids and esters in chloroform solution have been investigated by 1H and 13C NMR spectroscopy and Density Functional Theory (DFT) methods. Investigated ligands form 1:1 adducts in our experimental conditions, with stability constants in the order of several hundred mol-1. The exchange of ligands in solution is fast on the NMR spectroscopic timescale. The decrease of longitudinal relaxation times T1 in ligands in the presence of rhodium salt has been tested as the means of determination of the complexation site in ligands. The influence of complexation on chemical shifts in ligands was evaluated by a parameter complexation shift Δδ (Δδ = δadd - δlig). These parameters were positive (>0 ppm) and did not exceed 1 ppm for 1H NMR; and varied from ca. -5 to +15 ppm in the case of 13C NMR. The calculation by DFT methods using the B3LYP functional (structure optimization, electronic energy) and B3PW91 functional (shielding), and combinations of the (6-31G(2d), 6-311G++(2d,p), and LANL2DZ basis sets, followed by scaling procedures reproduced satisfactorily 1H and 13C chemical shifts and, with some limitations, allowed to estimate Δδ parameters.

  18. Development of a rapid method for the quantification of cellulose in tobacco by (13)C CP/MAS NMR.

    PubMed

    Jiang, Jinhui; Hu, Yonghua; Tian, Zhenfeng; Chen, Kaibo; Ge, Shaolin; Xu, Yingbo; Tian, Dong; Yang, Jun

    2016-01-01

    A method was developed for rapid quantitative determination of cellulose in tobacco by utilizing (13)C cross polarization magic angle spinning NMR spectroscopy ((13)C CP/MAS NMR). Sample powder was loaded into NMR rotor, which was customized rotor containing a matched silicon tube as an intensity reference. (13)C CP/MAS NMR spectra of tobacco samples were processed with spectral deconvolution to obtain the area of the C-1 resonance at 105.5ppm and the internal standard at 0ppm. The ratio between the area of 105.5ppm and 0ppm of a set of standard cellulose samples was used to construct a calibration curve. The cellulose content of a tobacco sample was determined by comparison of the ratio between the area of 105.5ppm and 0ppm to the calibration curve. Results of this developed method showed good agreement with those obtained from chemical analysis. The proposed method has such advantages of accuracy, quickness and efficiency, and could be an alternative to chemical analyses of cellulose.

  19. Effect of organic matter application on CP-MAS-13C-NMR spectra of humic acids from a brown soil

    NASA Astrophysics Data System (ADS)

    Dou, S.

    2009-04-01

    The humified SOM or humic substances (HS) composed of humic acid (HA), fulvic acid (FA) and humin (HM) represent the most microbially recalcitrant and stable reservoir of organic carbon in soil (Piccolo et al., 2004). OM applications can influence the amount and structural characteristics of HS(Dou et al., 2008). During the past few decades, there has been much research on HS, but their chemical structure is still not fully understood (Dong, 2006).CP-MAS-13C-NMR spectroscopy was considered as an effective method to study structures of HS without dissolving problem compared with liquid 13C-NMR (Conte et al., 1997; Dou et al., 2008). It can directly measure the carbon framework and reflect the nature of HS transformation after OM application (Spaccini et al., 2000). For that reason, this method was applied in this study. The objective of this paper was to clarify the effect of long term OM application on the changes of structural characteristics in HAs, which provided new information for improving soil fertility by OM application. The experiment was carried out on a brown soil (Paleudalf in USDA Soil Taxonomy) at Shenyang Agricultural University, Liaoning province, China (N41°48'-E123°25'). The experiment included 3 treatments: zero-treatment (CKbr), and two pig manure (PM) treatments (O1 and O2) at the rates of 0.9 t ha-1 and 1.8 t ha-1 of organic carbon, respectively. The samples of the HA fraction were extracted, separated and purified according to the method described by Dou et al. (1991). Elemental composition, Differential thermal analysis (DTA), -lgK value, FT-IR and CP-MAS- 13C-NMR of HAs were performed. Effects on the contents of orgaic carbon and its composition. The contents of TOC were from 8.77 g kg-1 to 12.25 g kg-1. The relative contents in TOC for WSS, HA, and FA were 6.87%, 14.2% and 19.8%. Comparing the CKbr, the contents of WSS, HA and FA for O1 and O2 increased, but relative contents of WSS and FA decreased. The content of the HA increased after

  20. Thermal maturity of type II kerogen from the New Albany Shale assessed by13C CP/MAS NMR

    USGS Publications Warehouse

    Werner-Zwanziger, U.; Lis, G.; Mastalerz, Maria; Schimmelmann, A.

    2005-01-01

    Thermal maturity of oil and gas source rocks is typically quantified in terms of vitrinite reflectance, which is based on optical properties of terrestrial woody remains. This study evaluates 13C CP/MAS NMR parameters in kerogen (i.e., the insoluble fraction of organic matter in sediments and sedimentary rocks) as proxies for thermal maturity in marine-derived source rocks where terrestrially derived vitrinite is often absent or sparse. In a suite of samples from the New Albany Shale (Middle Devonian to the Early Mississippian, Illinois Basin) the abundance of aromatic carbon in kerogen determined by 13C CP/MAS NMR correlates linearly well with vitrinite reflectance. ?? 2004 Elsevier Inc. All rights reserved.

  1. Large structure rearrangement of colicin ia channel domain after membrane binding from 2D 13C spin diffusion NMR.

    PubMed

    Luo, Wenbin; Yao, Xiaolan; Hong, Mei

    2005-05-01

    One of the main mechanisms of membrane protein folding is by spontaneous insertion into the lipid bilayer from the aqueous environment. The bacterial toxin, colicin Ia, is one such protein. To shed light on the conformational changes involved in this dramatic transfer from the polar to the hydrophobic milieu, we carried out 2D magic-angle spinning (13)C NMR experiments on the water-soluble and membrane-bound states of the channel-forming domain of colicin Ia. Proton-driven (13)C spin diffusion spectra of selectively (13)C-labeled protein show unequivocal attenuation of cross-peaks after membrane binding. This attenuation can be assigned to distance increases but not reduction of the diffusion coefficient. Analysis of the statistics of the interhelical and intrahelical (13)C-(13)C distances in the soluble protein structure indicates that the observed cross-peak reduction is well correlated with a high percentage of short interhelical contacts in the soluble protein. This suggests that colicin Ia channel domain becomes open and extended upon membrane binding, thus lengthening interhelical distances. In comparison, cross-peaks with similar intensities between the two states are dominated by intrahelical contacts in the soluble state. This suggests that the membrane-bound structure of colicin Ia channel domain may be described as a "molten globule", in which the helical secondary structure is retained while the tertiary structure is unfolded. This study demonstrates that (13)C spin diffusion NMR is a valuable tool for obtaining qualitative long-range distance constraints on membrane protein folding. PMID:15853348

  2. Triterpenes in the hexane extract of leaves of Olea europaea L.: analysis using 13C-NMR spectroscopy.

    PubMed

    Duquesnoy, Emilie; Castola, Vincent; Casanova, Joseph

    2007-01-01

    Two neutral triterpenes and a triterpene acid were identified and quantified directly, in the absence of any purification steps, in a precipitate obtained during the industrial extraction of the leaves of Olea europaea L. using 13C-NMR spectroscopy (spectrometer operating at 4.7 T equipped with a 10 mm probe). The method was optimised in order to reduce the duration of analysis with a routine NMR spectrometer. Together with long-chain linear compounds, erythrodiol, uvaol and oleanolic acid accounted for 27.3, 18.3 and 12.5% of the precipitate, respectively.

  3. High-field 13C NMR spectroscopy of tissue in Vivo. A double-resonance surface-coil probe

    NASA Astrophysics Data System (ADS)

    Reo, Nicholas V.; Ewy, Coleen S.; Siegfried, Barry A.; Ackerman, Joseph J. H.

    A double-resonance surface-coil NMR probe is described for performance of high-field (8.5 T) proton decoupled carbon-13 experiments with tissue in vivo. The probe may be accommodated in standard, 89 mm i.d. clear bore, commercial spectrometers and is suitable for studies utilizing small laboratory animals such as mice, hamsters, and rats. A coaxial coil design is employed (10 mm diameter 13C coil, 20 mm diameter 1H coil) which provides ca. 40 dB attenuation between the 13C observe and 1H decouple channels. The inherent efficiency of the surface-coil configuration provides a sensitivity comparable to a commercial probe of the same nominal dimension (10 mm Helmholtz coil) and assures adequate decoupling in conductive samples with ca. 3-5 W power. In the absence of 13C isotopic enrichment, NMR spectra of rat leg, liver, and brain in vivo provide signalto-noise sufficient for 10 min time resolution. Administration of 100 mg of 90% 13C-labeled glucose into a peripheral vein of a ca. 300 g rat resulted in a liver glucose resonance which could be monitored with good signal-to-noise and 3 min time resolution.

  4. Solubilization and localization of weakly polar lipids in unsonicated egg phosphatidylcholine: A sup 13 C MAS NMR study

    SciTech Connect

    Hamilton, J.A. ); Fujito, D.T.; Hammer, C.F. )

    1991-03-19

    The weakly polar lipids cholesteryl ester, triacylglycerol, and diacylglycerol incorporate to a limited extent into the lamellar structure of small unilamellar vesicles. The localization of the carbonyl group(s) at the aqueous interface was detected by ({sup 13}C)carbonyl chemical shift changes relative to the neat unhydrated lipid. This study uses {sup 13}C NMR to investigate the interactions of thes lipids with unsonicated (multilamellar) phosphatidylcholine, a model system for cellular membranes and surfaces of emulsion particles with low curvature. Magic angle spinning reduced the broad lines of the unsonicated dispersions to narrow lines comparable to those from sonicated dispersions. ({sup 13}C)Carbonyl chemical shifts revealed incorporation of the three lipids into the lamellar structure of the unsonicated phospholipids and a partial hydration of the carbonyl groups similar to that observed in small vesicles. Other properties of interfacial weakly polar lipids in multilayers were similar to those in small unilamellar bilayers. There is thus a general tendency of weakly polar lipids to incorparate at least to a small extent into the lamellar structure of phospholipids and take on interfacial properties that are distinct from their bulk-phase properties. This pool of surface-located lipid is likely to be directly involved in enzymatyic transformations and protein-mediated transport. The {sup 13}C magic angle spinning NMR method may be generally useful for determining the orientation of molecules in model membranes.

  5. NMR study of Met-1 human Angiogenin: (1)H, (13)C, (15)N backbone and side-chain resonance assignment.

    PubMed

    Tsika, Aikaterini C; Chatzileontiadou, Demetra S M; Leonidas, Demetres D; Spyroulias, Georgios A

    2016-10-01

    Here, we report the high yield expression and preliminary structural analysis via solution hetero-nuclear NMR spectroscopy of the recombinant Met-1 human Angiogenin. The analysis reveals a well folded as well as, a monomeric polypeptide. Τhe sequence-specific assignment of its (1)H, (15)N and (13)C resonances at high percentage was obtained. Also, using TALOS+ its secondary structure elements were determined.

  6. Effect of organic matter application on CP-MAS-13C-NMR spectra of humic acids from a brown soil

    NASA Astrophysics Data System (ADS)

    Dou, S.

    2009-04-01

    The humified SOM or humic substances (HS) composed of humic acid (HA), fulvic acid (FA) and humin (HM) represent the most microbially recalcitrant and stable reservoir of organic carbon in soil (Piccolo et al., 2004). OM applications can influence the amount and structural characteristics of HS(Dou et al., 2008). During the past few decades, there has been much research on HS, but their chemical structure is still not fully understood (Dong, 2006).CP-MAS-13C-NMR spectroscopy was considered as an effective method to study structures of HS without dissolving problem compared with liquid 13C-NMR (Conte et al., 1997; Dou et al., 2008). It can directly measure the carbon framework and reflect the nature of HS transformation after OM application (Spaccini et al., 2000). For that reason, this method was applied in this study. The objective of this paper was to clarify the effect of long term OM application on the changes of structural characteristics in HAs, which provided new information for improving soil fertility by OM application. The experiment was carried out on a brown soil (Paleudalf in USDA Soil Taxonomy) at Shenyang Agricultural University, Liaoning province, China (N41°48'-E123°25'). The experiment included 3 treatments: zero-treatment (CKbr), and two pig manure (PM) treatments (O1 and O2) at the rates of 0.9 t ha-1 and 1.8 t ha-1 of organic carbon, respectively. The samples of the HA fraction were extracted, separated and purified according to the method described by Dou et al. (1991). Elemental composition, Differential thermal analysis (DTA), -lgK value, FT-IR and CP-MAS- 13C-NMR of HAs were performed. Effects on the contents of orgaic carbon and its composition. The contents of TOC were from 8.77 g kg-1 to 12.25 g kg-1. The relative contents in TOC for WSS, HA, and FA were 6.87%, 14.2% and 19.8%. Comparing the CKbr, the contents of WSS, HA and FA for O1 and O2 increased, but relative contents of WSS and FA decreased. The content of the HA increased after

  7. Unraveling the 13C NMR Chemical Shifts in Single-Walled Carbon Nanotubes: Dependence on Diameter and Electronic Structure

    SciTech Connect

    Engtrakul, C.; Irurzun, V. M.; Gjersing, E. L.; Holt, J. M.; Larsen, B. A.; Resasco, D. E.; Blackburn, J. L.

    2012-03-14

    The atomic specificity afforded by nuclear magnetic resonance (NMR) spectroscopy could enable detailed mechanistic information about single-walled carbon nanotube (SWCNT) functionalization as well as the noncovalent molecular interactions that dictate ground-state charge transfer and separation by electronic structure and diameter. However, to date, the polydispersity present in as-synthesized SWCNT populations has obscured the dependence of the SWCNT {sup 13}C chemical shift on intrinsic parameters such as diameter and electronic structure, meaning that no information is gleaned for specific SWCNTs with unique chiral indices. In this article, we utilize a combination of {sup 13}C labeling and density gradient ultracentrifugation (DGU) to produce an array of {sup 13}C-labeled SWCNT populations with varying diameter, electronic structure, and chiral angle. We find that the SWCNT isotropic {sup 13}C chemical shift decreases systematically with increasing diameter for semiconducting SWCNTs, in agreement with recent theoretical predictions that have heretofore gone unaddressed. Furthermore, we find that the {sup 13}C chemical shifts for small diameter metallic and semiconducting SWCNTs differ significantly, and that the full-width of the isotropic peak for metallic SWCNTs is much larger than that of semiconducting nanotubes, irrespective of diameter.

  8. Experimental 25Mg and 13C NMR and Computational Modeling Studies of Amorphous Mg-Ca Carbonates

    NASA Astrophysics Data System (ADS)

    Singer, J. W.; Yazaydin, A. O.; Kirkpatrick, R. J.; Saharay, M.; Bowers, G. M.

    2012-12-01

    Nuclear magnetic resonance (NMR) spectroscopy of synthetic Mg-Ca amorphous carbonates (AMC-ACC) provides direct, element specific structural information about these complicated phases. The 13C, 25Mg, and 43Ca resonances are typically broad and span the chemical shift ranges of all the crystalline polymorphs in the Ca-Mg-CO3-H2O system. In a fashion similar to our previous analysis of 43Ca NMR results for ACC,1 here we integrate new experimental 13C and 25Mg spectra obtained at 20T for samples with Mg/(Ca+Mg) ratios from x=0 to x=1 with quantum chemical calculations of the NMR parameters of the crystalline phases using CASTEP calculations, simulations of the spectra using the SIMPSON software, and classical molecular dynamics calculations. XRD and 13C NMR results are in general agreement with the one-phase/two-phase model of ACC-AMC derived from thermochemical work by others.2 13C-NMR spectra of amorphous materials having intermediate compositions can not be completely fit by mechanical mixing of ACC and AMC end members—requiring a degree of Ca/Mg solid solution. Amorphous samples in two-phase region crystallize to assemblages of dolomite-like (x~0.5) and hydromagnesite-like (x~1) defective structures, but we also observe aragonite co-nucleation in the presence of excess water, indicative of a more complex evolution. While 43Ca NMR of X-ray amorphous materials shows featureless, symmetric, Gaussian line shapes, the large quadrupole moment of 25Mg gives rise to superposition of several quadrupolar line shapes representing different local structural environments. Singularities of static Mg spectra are best explained by local environments similar to nequehonite, hydromagnesite, and landsfordite. The spectra can not exclude minor contributions from anhydrous phases dolomite, huntite, and magnesite. Additional sites having very large quadrupolar coupling and/or site asymmetry are not explained by any known reference phases. CITATIONS (1) Singer, J. W.; Yazaydin, A. O

  9. Compositional differences among Chinese soy sauce types studied by (13)C NMR spectroscopy coupled with multivariate statistical analysis.

    PubMed

    Kamal, Ghulam Mustafa; Wang, Xiaohua; Bin Yuan; Wang, Jie; Sun, Peng; Zhang, Xu; Liu, Maili

    2016-09-01

    Soy sauce a well known seasoning all over the world, especially in Asia, is available in global market in a wide range of types based on its purpose and the processing methods. Its composition varies with respect to the fermentation processes and addition of additives, preservatives and flavor enhancers. A comprehensive (1)H NMR based study regarding the metabonomic variations of soy sauce to differentiate among different types of soy sauce available on the global market has been limited due to the complexity of the mixture. In present study, (13)C NMR spectroscopy coupled with multivariate statistical data analysis like principle component analysis (PCA), and orthogonal partial least square-discriminant analysis (OPLS-DA) was applied to investigate metabonomic variations among different types of soy sauce, namely super light, super dark, red cooking and mushroom soy sauce. The main additives in soy sauce like glutamate, sucrose and glucose were easily distinguished and quantified using (13)C NMR spectroscopy which were otherwise difficult to be assigned and quantified due to serious signal overlaps in (1)H NMR spectra. The significantly higher concentration of sucrose in dark, red cooking and mushroom flavored soy sauce can directly be linked to the addition of caramel in soy sauce. Similarly, significantly higher level of glutamate in super light as compared to super dark and mushroom flavored soy sauce may come from the addition of monosodium glutamate. The study highlights the potentiality of (13)C NMR based metabonomics coupled with multivariate statistical data analysis in differentiating between the types of soy sauce on the basis of level of additives, raw materials and fermentation procedures. PMID:27343582

  10. Spectroscopic analysis (FT-IR, FT-Raman and NMR) and molecular docking study of ethyl 2-(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)-acetate

    NASA Astrophysics Data System (ADS)

    El-Azab, Adel S.; Jalaja, K.; Abdel-Aziz, Alaa A.-M.; Al-Obaid, Abdulrahman M.; Sheena Mary, Y.; Yohannan Panicker, C.; Van Alsenoy, C.

    2016-09-01

    The vibrational wavenumbers, molecular structure, MEP, NLO, NBO and HOMO, LUMO analysis of Ethyl 2-(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)-acetate (EPDA) were reported. The change in electron density in the antibonding orbitals and stabilization energies have been calculated by NBO analysis to give clear evidence of stabilization in the hyperconjugation of hydrogen bonded interaction. The difference in HOMO and LUMO energy support the charge transfer interaction within the molecule. NMR studies and Fukui functions are also reported. From molecular electrostatic potential plot it is evident that the negative charge covers the carbonyl groups, phenyl rings and the positive region is over the CH2 groups with the acetate group. Molecular docking studies shows that the title compound forms a stable complex with pyrrole inhibitor and gives a binding affinity value of -8.3 kcal/mol and the results suggest that the compound might exhibit inhibitory activity against pyrrole inhibitor.

  11. Local structure and molecular motions in imidazolium hydrogen malonate crystal as studied by 2H and 13C NMR

    NASA Astrophysics Data System (ADS)

    Mizuno, M.; Chizuwa, M.; Umiyama, T.; Kumagai, Y.; Miyatou, T.; Ohashi, R.; Ida, T.; Tansho, M.; Shimizu, T.

    2015-04-01

    The local structure and molecular motion of the imidazolium hydrogen malonate crystal were investigated using solid-state 2H and 13C NMR. The imidazolium ion undergoes isotropic rotation, which is correlated with a defect in the crystal, as observed by 2H NMR broadline spectra above 263 K. A 180∘ flip of the imidazolium ion in the regular site was observed from 2H NMR quadrupole Carr-Purcell-Meiboom-Gill (QCPMG) spectra. The Grotthuss mechanism was accompanied by a 180∘ flip of the imidazolium ion in regular sites. Moreover, the proton transfer associated with the imidazolium ion of the defective crystal is important for proton conductivity of the imidazolium hydrogen malonate crystal.

  12. 1H and 13C NMR assignments of three nitrogen containing compounds from the mangrove endophytic fungus (ZZF08).

    PubMed

    Tao, Yiwen; Zeng, Xianjian; Mou, Chengbo; Li, Jun; Cai, Xiaoling; She, Zhigang; Zhou, Shining; Lin, Yongcheng

    2008-05-01

    A new natural product, named phomopsin A, 1-(meta-hydroxyphenyl)-4-hydroxy-3-isoquinolone (1), together with two known compounds cytochalasin H (2) and glucosylceramide (3), was isolated from the mangrove endophytic fungus Phomopsis sp. (ZZF08) obtained from the South China Sea coast. The structures were elucidated by 1D and 2D NMR experiments including COSY, HMQC, and HMBC. According to NMR and single-crystal X-ray diffraction, it was found that some assignments about (1)H and (13)C NMR data for cytochalasin H (2) were probably uncorrected in the previous reports. In our cytotoxicity assays, compound 1 showed moderate cytotoxicity toward KB cells with IC(50) at 28.0 microg ml(-1) and KBv200 cells with IC(50) at 16.8 microg ml(-1), and compound 2 exhibited strong cytotoxicity toward KB cells and KBv200 cells with IC(50) less than 1.25 microg ml(-1).

  13. 1H and 13C NMR assignments for two anthraquinones and two xanthones from the mangrove fungus (ZSUH-36).

    PubMed

    Shao, Changlun; She, Zhigang; Guo, Zhiyong; Peng, Hong; Cai, Xiaoling; Zhou, Shining; Gu, Yucheng; Lin, Yongcheng

    2007-05-01

    We report the unambiguous assignments of the (1)H and (13)C NMR spectra of one new natural product, namely, 6,8-di-O-methyl versiconol (1) together with one known anthraquinone aversin (2) and two xanthones 5-methoxysterigmatocystin (3) and sterigmatocystin (4). These compounds were all isolated from the mangrove endophytic fungus ZSUH-36 from the South China Sea. 1D and 2D NMR experiments including COSY, HMQC and HMBC were used to elucidate the structures. Variations in the (1)H NMR spectrum of 6,8-di-O-methyl versiconol (1) were also observed in the temperature range 25-75 degrees C. In addition, the plausible biogenetic path from 1 to 2 is discussed.

  14. Characterizing crystal disorder of trospium chloride: a comprehensive,(13) C CP/MAS NMR, DSC, FTIR, and XRPD study.

    PubMed

    Urbanova, Martina; Sturcova, Adriana; Brus, Jiri; Benes, Hynek; Skorepova, Eliska; Kratochvil, Bohumil; Cejka, Jan; Sedenkova, Ivana; Kobera, Libor; Policianova, Olivia; Sturc, Antonin

    2013-04-01

    Analysis of C cross-polarization magic angle spinning (CP/MAS) nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and X-ray powder diffraction data of trospium chloride (TCl) products crystallized from different mixtures of water-ethanol [φ(EtOH) = 0.5-1.0] at various temperatures (0°C, 20°C) and initial concentrations (saturated solution, 30%-50% excess of solvent) revealed extensive structural variability of TCl. Although (13) C CP/MAS NMR spectra indicated broad variety of structural phases arising from molecular disorder, temperature-modulated DSC identified presence of two distinct components in the products. FTIR spectra revealed alterations in the hydrogen bonding network (ionic hydrogen bond formation), whereas the X-ray diffraction reflected unchanged unit cell parameters. These results were explained by a two-component character of TCl products in which a dominant polymorphic form is accompanied by partly separated nanocrystalline domains of a secondary phase that does not provide clear Bragg reflections. These phases slightly differ in the degree of molecular disorder, in the quality of crystal lattice and hydrogen bonding network. It is also demonstrated that, for the quality control of such complex products, (13) C CP/MAS NMR spectroscopy combined with factor analysis (FA) can satisfactorily be used for categorizing the individual samples: FA of (13) C CP/MAS NMR spectra found clear relationships between the extent of molecular disorder and crystallization conditions. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1235-1248, 2013.

  15. Metabolic engineering applications of in vivo sup 31 P and sup 13 C NMR studies of Saccharomyces cerevisiae

    SciTech Connect

    Shanks, J.V.

    1989-01-01

    With intent to quantify NMR measurements as much as possible, analysis techniques of the in vivo {sup 31}P NMR spectrum are developed. A systematic procedure is formulated for estimating the relative intracellular concentrations of the sugar phosphates in S. cerevisiae from the {sup 31}P NMR spectrum. In addition, in vivo correlation of inorganic phosphate chemical shift with the chemical shifts of 3-phosphoglycerate, {beta}-fructose 1,6-diphosphate, fructose 6-phosphate, and glucose 6-phosphate are determined. Also, a method was developed for elucidation of the cytoplasmic and vacuolar components of inorganic phosphate in the {sup 31}P NMR spectrum of S. cerevisiae. An in vivo correlation relating the inorganic phosphate chemical shift of the vacuole with the chemical shift of the resonance for pyrophosphate and the terminal phosphate of polyphosphate (PP{sub 1}) is established. Transient measurements provided by {sup 31}P NMR are applied to reg1 mutant and standard strains. {sup 31}P and {sup 13}C NMR measurements are used to analyze the performance of recombinant strains in which the glucose phosphorylation step had been altered.

  16. Experimental (FT-IR and FT-Raman) and theoretical (HF and DFT) investigation, NMR, NBO, electronic properties and frequency estimation analyses on 2,4,5-trichlorobenzene sulfonyl chloride

    NASA Astrophysics Data System (ADS)

    Gayathri, R.; Arivazhagan, M.

    2012-11-01

    The present work deals with the structural, electronic, and vibrational analyses of the biomolecule 2,4,5-trichlorobenzene sulfonyl chloride (TCBSC). TCBSC is a novel pharmaceutical compound used in dyes, pesticides, pigments, fluorescence brighteners and intermediate for agricultural chemicals in the manufacture of insecticides. Quantum chemical calculation of geometrical structure and energies of TCBSC was carried out by density functional theory (B3LYP) and ab initio (HF) methods at 6-311+G(d,p) and 6-311++G(d,p) standard basis set. The stability of the molecule arising from hyperconjugative interaction and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. NMR analysis shows that the isotropic chemical shifts of carbon and hydrogen atom of TCBSC are giving the reasonable shielding to the molecule. Another interesting property shows nonlinear optical (NLO) behavior. Moreover, we have not only simulated highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) but also determined the transition state and energy band gap.

  17. Spectroscopic (FT-IR, FT-Raman and UV-Visible) investigations, NMR chemical shielding anisotropy (CSA) parameters of 2,6-Diamino-4-chloropyrimidine for dye sensitized solar cells using density functional theory.

    PubMed

    Gladis Anitha, E; Joseph Vedhagiri, S; Parimala, K

    2015-02-01

    The molecular structure, geometry optimization, vibrational frequencies of organic dye sensitizer 2,6-Diamino-4-chloropyrimidine (DACP) were studied based on Hartree-Fock (HF) and density functional theory (DFT) using B3LYP methods with 6-311++G(d,p) basis set. Ultraviolet-Visible (UV-Vis) spectrum was investigated by time dependent DFT (TD-DFT). Features of the electronic absorption spectrum in the UV-Visible regions were assigned based on TD-DFT calculation. The absorption bands are assigned to transitions. The interfacial electron transfer between semiconductor TiO2 electrode and dye sensitizer DACP is due to an electron injection process from excited dye to the semiconductor's conduction band. The observed and the calculated frequencies are found to be in good agreement. The energies of the frontier molecular orbitals (FMOS) have also been determined. The chemical shielding anisotropic (CSA) parameters are calculated from the NMR analysis, Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

  18. Vibrational analysis using FT-IR, FT-Raman spectra and HF-DFT methods and NBO, NLO, NMR, HOMO-LUMO, UV and electronic transitions studies on 2,2,4-trimethyl pentane.

    PubMed

    Suvitha, A; Periandy, S; Govindarajan, M; Gayathri, P

    2015-03-01

    In this work, the vibrational spectral analysis was carried out by using Raman and infrared spectroscopy in the range 100-4000cm(-1)and 50-4000cm(-1), respectively, for 2,2,4-Trimethyl Pentane, TMP (C8H18) molecule. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and geometrical parameter calculations based on Hartree Fock (HF) and density functional theory (DFT) method with 6-311++G(d,p) basis set. The scaled B3LYP/6-311++G(d,p) results shows the best agreement with the experimental values over the other method. The calculated HOMO and LUMO energies shows that charge transfer within the molecule. The physical reactions of single bond hydrocarbon TMP were investigated. The results of the calculations were applied to simulate spectra of the title compound, which shows the excellent agreement with observed spectra. Besides, Mulliken atomic charges, UV, frontier molecular orbital (FMO), MEP, NLO activity, Natural Bond-Orbital (NBO) analysis, NMR and thermodynamic properties of title molecule were also performed.

  19. Uranyl nitrate inhibits lactate gluconeogenesis in isolated human and mouse renal proximal tubules: A {sup 13}C-NMR study

    SciTech Connect

    Renault, Sophie; Faiz, Hassan; Gadet, Rudy; Ferrier, Bernard; Martin, Guy; Baverel, Gabriel; Conjard-Duplany, Agnes

    2010-01-01

    As part of a study on uranium nephrotoxicity, we investigated the effect of uranyl nitrate in isolated human and mouse kidney cortex tubules metabolizing the physiological substrate lactate. In the millimolar range, uranyl nitrate reduced lactate removal and gluconeogenesis and the cellular ATP level in a dose-dependent fashion. After incubation in phosphate-free Krebs-Henseleit medium with 5 mM L-[1-{sup 13}C]-, or L-[2-{sup 13}C]-, or L-[3-{sup 13}C]lactate, substrate utilization and product formation were measured by enzymatic and NMR spectroscopic methods. In the presence of 3 mM uranyl nitrate, glucose production and the intracellular ATP content were significantly reduced in both human and mouse tubules. Combination of enzymatic and NMR measurements with a mathematical model of lactate metabolism revealed an inhibition of fluxes through lactate dehydrogenase and the gluconeogenic enzymes in the presence of 3 mM uranyl nitrate; in human and mouse tubules, fluxes were lowered by 20% and 14% (lactate dehydrogenase), 27% and 32% (pyruvate carboxylase), 35% and 36% (phosphoenolpyruvate carboxykinase), and 39% and 45% (glucose-6-phosphatase), respectively. These results indicate that natural uranium is an inhibitor of renal lactate gluconeogenesis in both humans and mice.

  20. Solid-State Selective 13C Excitation and Spin Diffusion NMR to Resolve Spatial Dimensions in Plant Cell Walls

    SciTech Connect

    Foston, M.; Katahira, R.; Gjersing, E.; Davis, M. F.; Ragauskas, A. J.

    2012-02-15

    The average spatial dimensions between major biopolymers within the plant cell wall can be resolved using a solid-state NMR technique referred to as a {sup 13}C cross-polarization (CP) SELDOM (selectively by destruction of magnetization) with a mixing time delay for spin diffusion. Selective excitation of specific aromatic lignin carbons indicates that lignin is in close proximity to hemicellulose followed by amorphous and finally crystalline cellulose. {sup 13}C spin diffusion time constants (T{sub SD}) were extracted using a two-site spin diffusion theory developed for {sup 13}C nuclei under magic angle spinning (MAS) conditions. These time constants were then used to calculate an average lower-limit spin diffusion length between chemical groups within the plant cell wall. The results on untreated {sup 13}C enriched corn stover stem reveal that the lignin carbons are, on average, located at distances {approx}0.7-2.0 nm from the carbons in hemicellulose and cellulose, whereas the pretreated material had larger separations.

  1. Differentiation of histidine tautomeric states using 15N selectively filtered 13C solid-state NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Miao, Yimin; Cross, Timothy A.; Fu, Riqiang

    2014-08-01

    The histidine imidazole ring in proteins usually contains a mixture of three possible tautomeric states (two neutral - τ and π states and a charged state) at physiological pHs. Differentiating the tautomeric states is critical for understanding how the histidine residue participates in many structurally and functionally important proteins. In this work, one dimensional 15N selectively filtered 13C solid-state NMR spectroscopy is proposed to differentiate histidine tautomeric states and to identify all 13C resonances of the individual imidazole rings in a mixture of tautomeric states. When 15N selective 180° pulses are applied to the protonated or non-protonated nitrogen region, the 13C sites that are bonded to the non-protonated or protonated nitrogen sites can be identified, respectively. A sample of 13C, 15N labeled histidine powder lyophilized from a solution at pH 6.3 has been used to illustrate the usefulness of this scheme by uniquely assigning resonances of the neutral τ and charged states from the mixture.

  2. Comparative study for separation of atmospheric humic-like substance (HULIS) by ENVI-18, HLB, XAD-8 and DEAE sorbents: elemental composition, FT-IR, 1H NMR and off-line thermochemolysis with tetramethylammonium hydroxide (TMAH).

    PubMed

    Fan, Xingjun; Song, Jianzhong; Peng, Ping'an

    2013-11-01

    Humic-like substances (HULIS) are significant constituents of aerosols, and the isolation and characterization of HULIS by solid-phase extraction methods are dependent on the sorbents used. In this study, we used the following five methods: ENVI-18, HLB-M, HLB-N, XAD-8 and DEAE, to isolate atmospheric HULIS at an urban site. Then we conducted a comparative investigation of the HULIS chemical characteristics by means of elemental analysis, Fourier transform infrared spectroscopy, (1)H nuclear magnetic resonance spectroscopy and off-line thermochemolysis with tetramethylammonium hydroxide. The results indicate that HULIS isolated using different methods show many similarities in chemical composition and structure. Some differences were however also observed between the five isolated HULIS: HULISHLB-M contains a relatively high content of OCH group, compared to HULISENVI-18 and HULISXAD-8; HULISXAD-8 contains a relatively high content of hydrophobic and aromatic components, compared to HULISENVI-18 and HULISHLB-M; HULISDEAE contains the highest content of aromatic functional groups, as inferred by (1)H NMR spectra, but a great amount of salts generally present in the HULISDEAE and thereby limited the choices for characterizing the materials (i.e., elemental analysis and TMAH thermochemolysis); HULISHLB-N has relatively high levels of H and N, a high N/C atomic ratio, and includes N-containing functional groups, which suggests that it has been altered by 2% ammonia introduced in the eluents. In summary, we found that ENVI-18, HLB-M, and XAD-8 are preferable methods for isolation and characterization of HULIS in atmospheric aerosols. These results also suggest that caution is required when applying DEAE and HLB-N isolating methods for characterizing atmospheric HULIS.

  3. Selective {sup 2}H and {sup 13}C labeling in NMR analysis of solution protein structure and dynamics

    SciTech Connect

    LeMaster, D.M.

    1994-12-01

    Preparation of samples bearing combined isotope enrichment patterns has played a central role in the recent advances in NMR analysis of proteins in solution. In particular, uniform {sup 13}C, {sup 15}N enrichment has made it possible to apply heteronuclear multidimensional correlation experiments for the mainchain assignments of proteins larger than 30 KDa. In contrast, selective labeling approaches can offer advantages in terms of the directedness of the information provided, such as chirality and residue type assignments, as well as through enhancements in resolution and sensitivity that result from editing the spectral complexity, the relaxation pathways and the scalar coupling networks. In addition, the combination of selective {sup 13}C and {sup 2}H enrichment can greatly facilitate the determination of heteronuclear relaxation behavior.

  4. (13)C, (15)N CPMAS NMR and GIAO DFT calculations of stereoisomeric oxindole alkaloids from Cat's Claw (Uncaria tomentosa).

    PubMed

    Paradowska, Katarzyna; Wolniak, Michał; Pisklak, Maciej; Gliński, Jan A; Davey, Matthew H; Wawer, Iwona

    2008-11-01

    Oxindole alkaloids, isolated from the bark of Uncaria tomentosa [Willd. ex Schult.] Rubiaceae, are considered to be responsible for the biological activity of this herb. Five pentacyclic and two tetracyclic alkaloids were studied by solid-state NMR and theoretical GIAO DFT methods. The (13)C and (15)N CPMAS NMR spectra were recorded for mitraphylline, isomitraphylline, pteropodine (uncarine C), isopteropodine (uncarine E), speciophylline (uncarine D), rhynchophylline and isorhynchophylline. Theoretical GIAO DFT calculations of shielding constants provide arguments for identification of asymmetric centers and proper assignment of NMR spectra. These alkaloids are 7R/7S and 20R/20S stereoisomeric pairs. Based on the (13)C CP MAS chemical shifts the 7S alkaloids (delta C3 70-71ppm) can be easily and conveniently distinguished from 7R (deltaC3 74.5-74.9ppm), also 20R (deltaC20 41.3-41.7ppm) from the 20S (deltaC20 36.3-38.3ppm). The epiallo-type isomer (3R, 20S) of speciophylline is characterized by a larger (15)N MAS chemical shift of N4 (64.6ppm) than the allo-type (3S, 20S) of isopteropodine (deltaN4 53.3ppm). (15)N MAS chemical shifts of N1-H in pentacyclic alkaloids are within 131.9-140.4ppm.

  5. A solution NMR study of the selectively 13C, 15N-labeled peptaibol chrysospermin C in methanol.

    PubMed

    Anders, R; Wenschuh, H; Soskic, V; Fischer-Frühholz, S; Ohlenschläger, O; Dornberger, K; Brown, L R

    1998-07-01

    The conformation of the 19-residue peptaibol chrysospermin C in methanol has been investigated by NMR spectroscopy using selective 15N and 13C labeling of the alpha-aminoisobutyric acid (Aib) residues. Complete 1H and 13C sequential assignments, including stereospecific assignments for the heavily overlapped resonances from the two Cbeta methyl groups of the eight Aib residues, are reported for a peptaibol for the first time. An Aib residue followed by a Pro is an exception to previous suggestions regarding stereospecific assignment of the two Cbeta methyl groups of Aib residues. Local nuclear Overhauser effects and 3J(HNC') and 3J(HNCbeta) scalar couplings indicate that the phi angles of the Aib residues are restricted sterically to local conformations consistent with right-handed helices. Despite these constraints on the eight Aib residues, the NMR data for chrysospermin C in methanol are generally most consistent with an ensemble of transient conformations, including backbone conformations inconsistent with helical structures. Initial NMR measurements for chrysospermin C bound to micelles suggest structural and dynamic differences relative to alamethicin bound to micelles which may be related to differences in gating voltages for formation of ion channels.

  6. Humic acids as proxies for assessing different Mediterranean forest soils signatures using solid-state CPMAS 13C NMR spectroscopy.

    PubMed

    Duarte, Regina M B O; Fernández-Getino, Ana P; Duarte, Armando C

    2013-06-01

    Humic acids (HAs) of four representative forest soils profiles from Central Spain (two with different vegetation - pine and oak - but same parent material - granitie, and two with same vegetation - holm oak - but different parent material - granite and limestone) were investigated by solid-state cross polarization with magic angle spinning (13)C nuclear magnetic resonance (NMR) spectroscopy. The objectives included the investigation of the impact of different forest properties on HA composition, assessing how the structural characteristics of the HA vary with soil depth, and evaluating the role of HA as surrogates for mapping the different forest soils signatures using structural data derived from (13)C NMR spectroscopy. On average, alkyl C is the dominant C constituent (38-48% of the total NMR peak area) in all HA samples, followed by aromatic (12-22%) and O-alkyl C (12-19%), and finally carboxyl C (7.0-10%). The NMR data also indicated that HA composition is likely to be differently affected by the soil physico-chemical properties and type of forest vegetation. The structural characteristics of the HA from soil under oak did not differ broadly downward in the profile, whereas soil HA under pine forest exhibits a somewhat higher recalcitrant nature as a consequence of a higher degree of decomposition. The soil HA from holm oak forests differed from the other two forest soils, exhibiting a progressive decomposition of the alkyl C structures with increasing depth, while the carbohydrate-like indicator (O-alkyl C) is apparently being protected from mineralization in the horizons below the ground level. Overall, these differences in soil HA NMR signatures are an important diagnostic tool for understanding the role of different soil environmental factors on the structural composition of HA from Mediterranean forest soils. PMID:23332874

  7. Humic acids as proxies for assessing different Mediterranean forest soils signatures using solid-state CPMAS 13C NMR spectroscopy.

    PubMed

    Duarte, Regina M B O; Fernández-Getino, Ana P; Duarte, Armando C

    2013-06-01

    Humic acids (HAs) of four representative forest soils profiles from Central Spain (two with different vegetation - pine and oak - but same parent material - granitie, and two with same vegetation - holm oak - but different parent material - granite and limestone) were investigated by solid-state cross polarization with magic angle spinning (13)C nuclear magnetic resonance (NMR) spectroscopy. The objectives included the investigation of the impact of different forest properties on HA composition, assessing how the structural characteristics of the HA vary with soil depth, and evaluating the role of HA as surrogates for mapping the different forest soils signatures using structural data derived from (13)C NMR spectroscopy. On average, alkyl C is the dominant C constituent (38-48% of the total NMR peak area) in all HA samples, followed by aromatic (12-22%) and O-alkyl C (12-19%), and finally carboxyl C (7.0-10%). The NMR data also indicated that HA composition is likely to be differently affected by the soil physico-chemical properties and type of forest vegetation. The structural characteristics of the HA from soil under oak did not differ broadly downward in the profile, whereas soil HA under pine forest exhibits a somewhat higher recalcitrant nature as a consequence of a higher degree of decomposition. The soil HA from holm oak forests differed from the other two forest soils, exhibiting a progressive decomposition of the alkyl C structures with increasing depth, while the carbohydrate-like indicator (O-alkyl C) is apparently being protected from mineralization in the horizons below the ground level. Overall, these differences in soil HA NMR signatures are an important diagnostic tool for understanding the role of different soil environmental factors on the structural composition of HA from Mediterranean forest soils.

  8. Unraveling the complexity of protein backbone dynamics with combined (13)C and (15)N solid-state NMR relaxation measurements.

    PubMed

    Lamley, Jonathan M; Lougher, Matthew J; Sass, Hans Juergen; Rogowski, Marco; Grzesiek, Stephan; Lewandowski, Józef R

    2015-09-14

    Typically, protein dynamics involve a complex hierarchy of motions occurring on different time scales between conformations separated by a range of different energy barriers. NMR relaxation can in principle provide a site-specific picture of both the time scales and amplitudes of these motions, but independent relaxation rates sensitive to fluctuations in different time scale ranges are required to obtain a faithful representation of the underlying dynamic complexity. This is especially pertinent for relaxation measurements in the solid state, which report on dynamics in a broader window of time scales by more than 3 orders of magnitudes compared to solution NMR relaxation. To aid in unraveling the intricacies of biomolecular dynamics we introduce (13)C spin-lattice relaxation in the rotating frame (R1ρ) as a probe of backbone nanosecond-microsecond motions in proteins in the solid state. We present measurements of (13)C'R1ρ rates in fully protonated crystalline protein GB1 at 600 and 850 MHz (1)H Larmor frequencies and compare them to (13)C'R1, (15)N R1 and R1ρ measured under the same conditions. The addition of carbon relaxation data to the model free analysis of nitrogen relaxation data leads to greatly improved characterization of time scales of protein backbone motions, minimizing the occurrence of fitting artifacts that may be present when (15)N data is used alone. We also discuss how internal motions characterized by different time scales contribute to (15)N and (13)C relaxation rates in the solid state and solution state, leading to fundamental differences between them, as well as phenomena such as underestimation of picosecond-range motions in the solid state and nanosecond-range motions in solution.

  9. Hydrothermal carbon from biomass: structural differences between hydrothermal and pyrolyzed carbons via 13C solid state NMR.

    PubMed

    Falco, Camillo; Perez Caballero, Fernando; Babonneau, Florence; Gervais, Christel; Laurent, Guillaume; Titirici, Maria-Magdalena; Baccile, Niki

    2011-12-01

    The objective of this paper is to better describe the structure of the hydrothermal carbon (HTC) process and put it in relationship with the more classical pyrolytic carbons. Indeed, despite the low energetic impact and the number of applications described so far for HTC, very little is known about the structure, reaction mechanism, and the way these materials relate to coals. Are HTC and calcination processes equivalent? Are the structures of the processed materials related to each other in any way? Which is the extent of polyaromatic hydrocarbons (PAH) inside HTC? In this work, the effect of hydrothermal treatment and pyrolysis are compared on glucose, a good model carbohydrate; a detailed single-quantum double-quantum (SQ-DQ) solid state (13)C NMR study of the HTC and calcined HTC is used to interpret the spectral region corresponding to the signal of furanic and arene groups. These data are compared to the spectroscopic signatures of calcined glucose, starch, and xylose. A semiquantitative analysis of the (13)C NMR spectra provides an estimation of the furanic-to-arene ratio which varies from 1:1 to 4:1 according to the processing conditions and carbohydrate employed. In addition, we formulate some hypothesis, validated by DFT (density functional theory) modeling associated with (13)C NMR chemical shifts calculations, about the possible furan-rich structural intermediates that occur in the coalification process leading to condensed polyaromatic structures. In combination with a broad parallel study on the HTC processing conditions effect on glucose, cellulose, and raw biomass (Falco, C.; Baccile, N.; Titirici, M.-M. Green Chem., 2011, DOI: 10.1039/C1GC15742F), we propose a broad reaction scheme and in which we show that, through HTC, it is possible to tune the furan-to-arene ratio composing the aromatic core of the produced HTC carbons, which is not possible if calcination is used alone, in the temperature range below 350 °C. PMID:22050004

  10. Phase behavior and 13C NMR spectroscopic analysis of the mixed methane + ethane + propane hydrates in mesoporous silica gels.

    PubMed

    Lee, Seungmin; Cha, Inuk; Seo, Yongwon

    2010-11-25

    In this study, the phase behavior and quantitative determination of hydrate composition and cage occupancy for the mixed CH(4) + C(2)H(6) + C(3)H(8) hydrates were closely investigated through the experimental measurement of three-phase hydrate (H)-water-rich liquid (L(W))-vapor (V) equilibria and (13)C NMR spectra. To examine the effect of pore size and salinity, we measured hydrate phase equilibria for the quaternary CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) + water mixtures in silica gel pores of nominal diameters of 6.0, 15.0, and 30.0 nm and for the quinary CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) + NaCl + water mixtures of two different NaCl concentrations (3 and 10 wt %) in silica gel pores of a nominal 30.0 nm diameter. The value of hydrate-water interfacial tension for the CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) hydrate was found to be 47 ± 4 mJ/m(2) from the relation of the dissociation temperature depression with the pore size of silica gels at a given pressure. At a specified temperature, three-phase H-L(W)-V equilibrium curves of pore hydrates were shifted to higher pressure regions depending on pore sizes and NaCl concentrations. From the cage-dependent (13)C NMR chemical shifts of enclathrated guest molecules, the mixed CH(4) (90%) + C(2)H(6) (7%) + C(3)H(8) (3%) gas hydrate was confirmed to be structure II. The cage occupancies of each guest molecule and the hydration number of the mixed gas hydrates were also estimated from the (13)C NMR spectra.

  11. 13C, 2h NMR studies of structural and dynamical modifications of glucose-exposed porcine aortic elastin.

    PubMed

    Silverstein, Moshe C; Bilici, Kübra; Morgan, Steven W; Wang, Yunjie; Zhang, Yanhang; Boutis, Gregory S

    2015-04-01

    Elastin, the principal component of the elastic fiber of the extracellular matrix, imparts to vertebrate tissues remarkable resilience and longevity. This work focuses on elucidating dynamical and structural modifications of porcine aortic elastin exposed to glucose by solid-state NMR spectroscopic and relaxation methodologies. Results from macroscopic stress-strain tests are also presented and indicate that glucose-treated elastin is mechanically stiffer than the same tissue without glucose treatment. These measurements show a large hysteresis in the stress-strain behavior of glucose-treated elastin-a well-known signature of viscoelasticity. Two-dimensional relaxation NMR methods were used to investigate the correlation time, distribution, and population of water in these samples. Differences are observed between the relative populations of water, whereas the measured correlation times of tumbling motion of water across the samples were similar. (13)C magic-angle-spinning NMR methods were applied to investigate structural and dynamical modifications after glucose treatment. Although some overall structure is preserved, the process of glucose exposure results in more heterogeneous structures and slower mobility. The correlation times of tumbling motion of the (13)C-(1)H internuclear vectors in the glucose-treated sample are larger than in untreated samples, pointing to their more rigid structure. The (13)C cross-polarization spectra reveal a notably increased α-helical character in the alanine motifs after glucose exposure. Results from molecular dynamics simulations are provided that add further insight into dynamical and structural changes of a short repeat, [VPGVG]5, an alanine pentamer, desmosine, and isodesmosine sites with and without glucose. The simulations point to changes in the entropic and energetic contributions in the retractive forces of VPGVG and AAAAA motifs. The most notable change is the increase of the energetic contribution in the retractive

  12. 13C, 2H NMR Studies of Structural and Dynamical Modifications of Glucose-Exposed Porcine Aortic Elastin

    PubMed Central

    Silverstein, Moshe C.; Bilici, Kübra; Morgan, Steven W.; Wang, Yunjie; Zhang, Yanhang; Boutis, Gregory S.

    2015-01-01

    Elastin, the principal component of the elastic fiber of the extracellular matrix, imparts to vertebrate tissues remarkable resilience and longevity. This work focuses on elucidating dynamical and structural modifications of porcine aortic elastin exposed to glucose by solid-state NMR spectroscopic and relaxation methodologies. Results from macroscopic stress-strain tests are also presented and indicate that glucose-treated elastin is mechanically stiffer than the same tissue without glucose treatment. These measurements show a large hysteresis in the stress-strain behavior of glucose-treated elastin—a well-known signature of viscoelasticity. Two-dimensional relaxation NMR methods were used to investigate the correlation time, distribution, and population of water in these samples. Differences are observed between the relative populations of water, whereas the measured correlation times of tumbling motion of water across the samples were similar. 13C magic-angle-spinning NMR methods were applied to investigate structural and dynamical modifications after glucose treatment. Although some overall structure is preserved, the process of glucose exposure results in more heterogeneous structures and slower mobility. The correlation times of tumbling motion of the 13C-1H internuclear vectors in the glucose-treated sample are larger than in untreated samples, pointing to their more rigid structure. The 13C cross-polarization spectra reveal a notably increased α-helical character in the alanine motifs after glucose exposure. Results from molecular dynamics simulations are provided that add further insight into dynamical and structural changes of a short repeat, [VPGVG]5, an alanine pentamer, desmosine, and isodesmosine sites with and without glucose. The simulations point to changes in the entropic and energetic contributions in the retractive forces of VPGVG and AAAAA motifs. The most notable change is the increase of the energetic contribution in the retractive force

  13. Biosynthesis of pyrroloquinoline quinone. 1. Identification of biosynthetic precursors using /sup 13/C labeling and NMR spectroscopy

    SciTech Connect

    Houck, D.R.; Hanners, J.L.; Unkefer, C.J.

    1988-09-28

    The biosynthesis of pyrroloquinoline quinone (PQQ) in the methylotropic bacterium methylobacterium AM1 has been investigated using /sup 13/C-labelling of the products and NMR spectroscopy. The data indicated that the quinoline portion of PQQ is formed by a novel condensation of N-1, C-2, -3, and -4 of glutamate with a symmetrical six-carbon ring derived from the shikimate pathway. It is postulated that tyrosine is the shikimate-derived percursor, since pyrrole could be formed by the internal cyclization of the amino acid backbone. 18 references, 2 figures, 2 tables.

  14. Characterization of aging in organic materials on atomic-, meso- and macro-length scales by {sup 13}C NMR spectroscopy

    SciTech Connect

    Assink, R.A.; Jamison, G.M.; Alam, T.M.; Gillen, K.T.

    1997-10-01

    A fundamental understanding of aging in an organic material requires that one understand how aging affects the chemical structure of a material, and how these chemical changes are related to the material`s macroscopic properties. This level of understanding is usually achieved by examining the material on a variety of length scales ranging from atomic to meso-scale to macroscopic. The authors are developing and applying several {sup 13}C nuclear magnetic resonance (NMR) spectroscopy experiments to characterize the aging process of organic materials over a broad range of length scales. Examples of studies which range from atomic to macroscopic will be presented.

  15. /sup 13/C NMR spectroscopy in the analysis of conjugate metabolites in the bile of fish exposed to petroleum

    SciTech Connect

    Hellou, J.; Banoub, J.H.; Payne, J.F.

    1986-01-01

    The first natural abundance /sup 13/C NMR investigation of a complex mixture of conjugate metabolites obtained from the gall bladder bile of fish exposed to hydrocarbons is presented. Cunners were exposed to water accommodated No. 2 fuel oil containing about 68% saturates and 22% aromatics. Spectral analysis indicated that the hydrocarbon derivatives were present predominantly as ..beta..-glucuronides, with the oxygen at carbon-1 of glucuronic acid preferentially attached to an aliphatic carbon. The conjugate metabolites were enriched in aromatic-type carbons when compared to the fuel oil or the aromatic fraction of oil.

  16. Use of solid-state 13C NMR in structural studies of humic acids and humin from Holocene sediments

    USGS Publications Warehouse

    Hatcher, P.G.; VanderHart, D.L.; Earl, W.L.

    1980-01-01

    13C NMR spectra of solid humic substances in Holocene sediments have been obtained using cross polarization with magic-angle sample spinning techniques. The results demonstrate that this technique holds great promise for structural characterizations of complex macromolecular substances such as humin and humic acids. Quantifiable distinctions can be made between structural features of aquatic and terrestrial humic substances. The aliphatic carbons of the humic substances are dominant components suggestive of input from lipid-like materials. An interesting resemblance is also noted between terrestrial humic acid and humin spectra. ?? 1980.

  17. Identification and quantitative determination of carbohydrates in ethanolic extracts of two conifers using 13C NMR spectroscopy.

    PubMed

    Duquesnoy, Emilie; Castola, Vincent; Casanova, Joseph

    2008-04-01

    We developed a method for the direct identification and quantification of carbohydrates in raw vegetable extracts using (13)C NMR spectroscopy without any preliminary step of precipitation or reduction of the components. This method has been validated (accuracy, precision and response linearity) using pure compounds and artificial mixtures before being applied to authentic ethanolic extracts of pine needles, pine wood and pine cones and fir twigs. We determined that carbohydrates represented from 15% to 35% of the crude extracts in which pinitol was the principal constituent accompanied by arabinitol, mannitol, glucose and fructose.

  18. Spectral density mapping at multiple magnetic fields suitable for 13C NMR relaxation studies

    NASA Astrophysics Data System (ADS)

    Kadeřávek, Pavel; Zapletal, Vojtěch; Fiala, Radovan; Srb, Pavel; Padrta, Petr; Přecechtělová, Jana Pavlíková; Šoltésová, Mária; Kowalewski, Jozef; Widmalm, Göran; Chmelík, Josef; Sklenář, Vladimír; Žídek, Lukáš

    2016-05-01

    Standard spectral density mapping protocols, well suited for the analysis of 15N relaxation rates, introduce significant systematic errors when applied to 13C relaxation data, especially if the dynamics is dominated by motions with short correlation times (small molecules, dynamic residues of macromolecules). A possibility to improve the accuracy by employing cross-correlated relaxation rates and on measurements taken at several magnetic fields has been examined. A suite of protocols for analyzing such data has been developed and their performance tested. Applicability of the proposed protocols is documented in two case studies, spectral density mapping of a uniformly labeled RNA hairpin and of a selectively labeled disaccharide exhibiting highly anisotropic tumbling. Combination of auto- and cross-correlated relaxation data acquired at three magnetic fields was applied in the former case in order to separate effects of fast motions and conformational or chemical exchange. An approach using auto-correlated relaxation rates acquired at five magnetic fields, applicable to anisotropically moving molecules, was used in the latter case. The results were compared with a more advanced analysis of data obtained by interpolation of auto-correlated relaxation rates measured at seven magnetic fields, and with the spectral density mapping of cross-correlated relaxation rates. The results showed that sufficiently accurate values of auto- and cross-correlated spectral density functions at zero and 13C frequencies can be obtained from data acquired at three magnetic fields for uniformly 13C -labeled molecules with a moderate anisotropy of the rotational diffusion tensor. Analysis of auto-correlated relaxation rates at five magnetic fields represents an alternative for molecules undergoing highly anisotropic motions.

  19. Noninvasive measurements of glycogen in perfused mouse livers using chemical exchange saturation transfer NMR and comparison to (13)C NMR spectroscopy.

    PubMed

    Miller, Corin O; Cao, Jin; Chekmenev, Eduard Y; Damon, Bruce M; Cherrington, Alan D; Gore, John C

    2015-06-01

    Liver glycogen represents an important physiological form of energy storage. It plays a key role in the regulation of blood glucose concentrations, and dysregulations in hepatic glycogen metabolism are linked to many diseases including diabetes and insulin resistance. In this work, we develop, optimize, and validate a noninvasive protocol to measure glycogen levels in isolated perfused mouse livers using chemical exchange saturation transfer (CEST) NMR spectroscopy. Model glycogen solutions were used to determine optimal saturation pulse parameters which were then applied to intact perfused mouse livers of varying glycogen content. Glycogen measurements from serially acquired CEST Z-spectra of livers were compared with measurements from interleaved natural abundance (13)C NMR spectra. Experimental data revealed that CEST-based glycogen measurements were highly correlated with (13)C NMR glycogen spectra. Monte Carlo simulations were then used to investigate the inherent (i.e., signal-to-noise-based) errors in the quantification of glycogen with each technique. This revealed that CEST was intrinsically more precise than (13)C NMR, although in practice may be prone to other errors induced by variations in experimental conditions. We also observed that the CEST signal from glycogen in liver was significantly less than that observed from identical amounts in solution. Our results demonstrate that CEST provides an accurate, precise, and readily accessible method to noninvasively measure liver glycogen levels and their changes. Furthermore, this technique can be used to map glycogen distributions via conventional proton magnetic resonance imaging, a capability universally available on clinical and preclinical magnetic resonance imaging (MRI) scanners vs (13)C detection, which is limited to a small fraction of clinical-scale MRI scanners. PMID:25946616

  20. Noninvasive measurements of glycogen in perfused mouse livers using chemical exchange saturation transfer NMR and comparison to (13)C NMR spectroscopy.

    PubMed

    Miller, Corin O; Cao, Jin; Chekmenev, Eduard Y; Damon, Bruce M; Cherrington, Alan D; Gore, John C

    2015-06-01

    Liver glycogen represents an important physiological form of energy storage. It plays a key role in the regulation of blood glucose concentrations, and dysregulations in hepatic glycogen metabolism are linked to many diseases including diabetes and insulin resistance. In this work, we develop, optimize, and validate a noninvasive protocol to measure glycogen levels in isolated perfused mouse livers using chemical exchange saturation transfer (CEST) NMR spectroscopy. Model glycogen solutions were used to determine optimal saturation pulse parameters which were then applied to intact perfused mouse livers of varying glycogen content. Glycogen measurements from serially acquired CEST Z-spectra of livers were compared with measurements from interleaved natural abundance (13)C NMR spectra. Experimental data revealed that CEST-based glycogen measurements were highly correlated with (13)C NMR glycogen spectra. Monte Carlo simulations were then used to investigate the inherent (i.e., signal-to-noise-based) errors in the quantification of glycogen with each technique. This revealed that CEST was intrinsically more precise than (13)C NMR, although in practice may be prone to other errors induced by variations in experimental conditions. We also observed that the CEST signal from glycogen in liver was significantly less than that observed from identical amounts in solution. Our results demonstrate that CEST provides an accurate, precise, and readily accessible method to noninvasively measure liver glycogen levels and their changes. Furthermore, this technique can be used to map glycogen distributions via conventional proton magnetic resonance imaging, a capability universally available on clinical and preclinical magnetic resonance imaging (MRI) scanners vs (13)C detection, which is limited to a small fraction of clinical-scale MRI scanners.

  1. (1)H and (13)C NMR assignments for two new steroids from the coral Chromonephthea sp.

    PubMed

    Geng, Hua-Wei; Liao, Xiao-Jian; Xu, Shi-Hai

    2009-04-01

    Two new steroids isolated from EtOH extracts of the South China Sea soft coral Chromonephthea sp. were identified. One-dimensional (1D) and two-dimensional (2D) NMR experiments including COSY, HSQC, HMBC and NOESY were used for the determination of their structure.

  2. 13C NMR Metabolomic Evaluation of Immediate and Delayed Mild Hypothermia in Cerebrocortical Slices After Oxygen-Glucose Deprivation

    PubMed Central

    Liu, Jia; Segal, Mark; Kelly, Mark J.S.; Pelton, Jeffrey G.; Kim, Myungwon; James, Thomas L.; Litt, Lawrence

    2013-01-01

    Background Mild brain hypothermia (32°C–34°C) after human neonatal asphyxia improves neurodevelopmental outcomes. Astrocytes but not neurons have pyruvate carboxylase (PC) and an acetate uptake transporter. 13C NMR spectroscopy of rodent brain extracts after administering [1-13C]glucose and [1,2-13C]acetate can distinguish metabolic differences between glia and neurons, and tricarboxylic acid cycle (TCA cycle) entry via pyruvate dehydrogenase (PDH) and PC. Methods Neonatal rat cerebrocortical slices receiving a 13C-acetate/glucose mixture underwent a 45-min asphyxia simulation via oxygen-glucose-deprivation (OGD) followed by 6 h of recovery. Protocols in three groups of N = 3 experiments were identical except for temperature management. The three temperature groups were: normothermia (37°C), hypothermia (32°C for 3.75 h beginning at OGD start), and delayed hypothermia (32°C for 3.75 h, beginning 15 min after OGD start). Multivariate analysis of nuclear magnetic resonance metabolite quantifications included principal component analyses and the L1-Penalized Regularized Regression algorithm known as the Least Absolute Shrinkage and Selection Operator (LASSO). Results The most significant metabolite difference (p < 0.0056) was [2-13C]glutamine’s higher final/control ratio for the Hypothermia group (1.75 ± 0.12) compared to ratios for the Delayed (1.12 ± 0.12) and Normothermia group (0.94 ± 0.06), implying a higher PC/PDH ratio for glutamine formation. LASSO found the most important metabolites associated with adenosine triphosphate preservation: [3,4-13C]glutamate—produced via PDH entry, [2-13C]taurine--an important osmolyte, and phosphocreatine. Final principal component analyses scores plots suggested separate cluster formation for the hypothermia group, but with insufficient data for statistical significance. Conclusions Starting mild hypothermia simultaneously with OGD, compared with delayed starting or no hypothermia, has higher PC throughput

  3. Ab Initio Calculations of Possible γ-Gauche Effects in the 13C-NMR for Methine and Carbonyl Carbons in Precise Polyethylene Acrylic Acid Copolymers

    SciTech Connect

    Alam, Todd

    2013-07-29

    The impacts of local polymer chain conformations on the methine and carbonyl 13C-NMR chemical shifts for polyethylene acrylic acid p(E-AA) copolymers were predicted using ab initio methods. Using small molecular cluster models, the magnitude and sign of the γ-gauche torsional angle effect, along with the impact of local tetrahedral structure distortions near the carbonyl group, on the 13C-NMR chemical shifts were determined. These 13C-NMR chemical shift variations were compared to the experimental trends observed for precise p(E-AA) copolymers as a function acid group spacing and degree of zinc-neutralization in the corresponding p(E-AA) ionomers. These ab initio calculations address the future ability of 13C-NMR chemical shift variations to provide information about the local chain conformations in p(E-AA) copolymer materials.

  4. 13C and 1H NMR (Nuclear Magnetic Resonance) studies of solid polyolefines

    NASA Technical Reports Server (NTRS)

    Cudby, M. E. A.; Harris, R. K.; Metcalfe, K.; Packer, K. J.; Smith, P. W. R.

    1983-01-01

    The basis of H-1 and C-13 high-resolution NMR investigations of solid polymers is outlined. The C-13 NMR spectra of solid syndiotactic and isotactic polypropene are discussed and their interpretation in terms of conformation and chain-packing effects are reviewed. The effects of decreasing temperature on the C-13 high-resolution spectrum of an annealed sample of isotactic polypropene is described and interpreted in terms of the crystal structure. The question of the proportion of the sample giving rise to C-13 signals is addressed and some results reported. The main cause for observing only part of the total sample is shown to be the H-1 rotating frame spin-lattice relaxation behavior. The H-1 spin-lattice relaxation and spectral characteristics of a number of polyolefin samples are summarized and the role of spin-diffusion discussed.

  5. Experimental and theoretical (FT-IR, FT-Raman, UV-vis, NMR) spectroscopic analysis and first order hyperpolarizability studies of non-linear optical material: (2E)-3-[4-(methylsulfanyl) phenyl]-1-(4-nitrophenyl) prop-2-en-1-one using density functional theory

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Deval, Vipin; Tandon, Poonam; Gupta, Archana; Deepak D'silva, E.

    2014-09-01

    A combined experimental and theoretical investigation on FT-IR, FT-Raman, NMR, UV-vis spectra of a chalcone derivative (2E)-3-[4-(methylsulfanyl) phenyl]-1-(4-nitrophenyl) prop-2-en-1-one (4N4MSP) has been reported. 4N4MSP has two planar rings connected through conjugated double bond and it provides a necessary configuration to show non-linear optical (NLO) response. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set combination. The analysis of the fundamental modes was made with the help of potential energy distribution (PED). Molecular electrostatic potential (MEP) surface was plotted over the geometry primarily for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The delocalization of electron density of various constituents of the molecule has been discussed with the aid of NBO analysis. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were calculated by time-dependent density functional theory (TD-DFT) and the results complement the experimental findings. The recorded and calculated 1H chemical shifts in gas phase and MeOD solution are gathered for reliable calculations of magnetic properties. Thermodynamic properties like heat capacity (C°p,m), entropy (S°m), enthalpy (H°m) have been calculated for the molecule at the different temperatures. Based on the finite-field approach, the non-linear optical (NLO) parameters such as dipole moment, mean polarizability, anisotropy of polarizability and first order hyperpolarizability of 4N4MSP molecule are calculated. The predicted first hyperpolarizability shows that the molecule has a reasonably good nonlinear optical (NLO) behavior.

  6. Experimental and theoretical (FT-IR, FT-Raman, UV-vis, NMR) spectroscopic analysis and first order hyperpolarizability studies of non-linear optical material: (2E)-3-[4-(methylsulfanyl) phenyl]-1-(4-nitrophenyl) prop-2-en-1-one using density functional theory.

    PubMed

    Kumar, Amit; Deval, Vipin; Tandon, Poonam; Gupta, Archana; Deepak D'silva, E

    2014-09-15

    A combined experimental and theoretical investigation on FT-IR, FT-Raman, NMR, UV-vis spectra of a chalcone derivative (2E)-3-[4-(methylsulfanyl) phenyl]-1-(4-nitrophenyl) prop-2-en-1-one (4N4MSP) has been reported. 4N4MSP has two planar rings connected through conjugated double bond and it provides a necessary configuration to show non-linear optical (NLO) response. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) with B3LYP functional and 6-311++G(d,p) basis set combination. The analysis of the fundamental modes was made with the help of potential energy distribution (PED). Molecular electrostatic potential (MEP) surface was plotted over the geometry primarily for predicting sites and relative reactivities towards electrophilic and nucleophilic attack. The delocalization of electron density of various constituents of the molecule has been discussed with the aid of NBO analysis. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were calculated by time-dependent density functional theory (TD-DFT) and the results complement the experimental findings. The recorded and calculated 1H chemical shifts in gas phase and MeOD solution are gathered for reliable calculations of magnetic properties. Thermodynamic properties like heat capacity (C°p,m), entropy (S°m), enthalpy (H°m) have been calculated for the molecule at the different temperatures. Based on the finite-field approach, the non-linear optical (NLO) parameters such as dipole moment, mean polarizability, anisotropy of polarizability and first order hyperpolarizability of 4N4MSP molecule are calculated. The predicted first hyperpolarizability shows that the molecule has a reasonably good nonlinear optical (NLO) behavior.

  7. Recognition of Membrane Sterols by Polyene Antifungals Amphotericin B and Natamycin, A 13C MAS NMR Study

    PubMed Central

    Ciesielski, Filip; Griffin, David C.; Loraine, Jessica; Rittig, Michael; Delves-Broughton, Joss; Bonev, Boyan B.

    2016-01-01

    The molecular action of polyene macrolides with antifungal activity, amphotericin B and natamycin, involves recognition of sterols in membranes. Physicochemical and functional studies have contributed details to understanding the interactions between amphotericin B and ergosterol and, to a lesser extent, with cholesterol. Fewer molecular details are available on interactions between natamycin with sterols. We use solid state 13C MAS NMR to characterize the impact of amphotericin B and natamycin on mixed lipid membranes of DOPC/cholesterol or DOPC/ergosterol. In cholesterol-containing membranes, amphotericin B addition resulted in marked increase in both DOPC and cholesterol 13C MAS NMR linewidth, reflecting membrane insertion and cooperative perturbation of the bilayer. By contrast, natamycin affects little either DOPC or cholesterol linewidth but attenuates cholesterol resonance intensity preferentially for sterol core with lesser impact on the chain. Ergosterol resonances, attenuated by amphotericin B, reveal specific interactions in the sterol core and chain base. Natamycin addition selectively augmented ergosterol resonances from sterol core ring one and, at the same time, from the end of the chain. This puts forward an interaction model similar to the head-to-tail model for amphotericin B/ergosterol pairing but with docking on opposite sterol faces. Low toxicity of natamycin is attributed to selective, non-cooperative sterol engagement compared to cooperative membrane perturbation by amphotericin B. PMID:27379235

  8. Evolution of organic matter during composting of different organic wastes assessed by CPMAS {sup 13}C NMR spectroscopy

    SciTech Connect

    Caricasole, P.; Provenzano, M.R.; Senesi, N.

    2011-03-15

    In this paper, the evolution of organic matter (OM) during composting of different mixtures of various organic wastes was assessed by means of chemical analyses and CPMAS {sup 13}C NMR spectroscopy measured during composting. The trends of temperatures and C/N ratios supported the correct evolution of the processes. The CPMAS {sup 13}C NMR spectra of all composting substrates indicated a reduction in carbohydrates and an increase in aromatic, phenolic, carboxylic and carbonylic C which suggested a preference by microorganisms for easily degradable C molecules. The presence of hardly degradable pine needles in one of the substrates accounted for the lowest increase in alkyl C and the lowest reduction in carbohydrates and carboxyl C as opposite to another substrate characterized by the presence of a highly degradable material such as spent yeast from beer production, which showed the highest increase of the alkyl C/O-alkyl C ratio. The highest increase of COOH deriving by the oxidative degradation of cellulose was shown by a substrate composed by about 50% of plant residues. The smallest increases in alkyl C/O-alkyl C ratio and in polysaccharides were associated to the degradation of proteins and lipids which are major components of sewage sludge. Results obtained were related to the different composition of fresh organic substrates and provided evidence of different OM evolution patterns as a function of the initial substrate composition.

  9. (13)C NMR characterization of triacylglycerols of Moringa oleifera seed oil: an "oleic-vaccenic acid" oil.

    PubMed

    Vlahov, Giovanna; Chepkwony, Paul Kiprono; Ndalut, Paul K

    2002-02-27

    The composition of acyl chains and their positions in the triacylglycerols of the oil extracted from seeds of Moringa oleifera were studied by (13)C NMR spectroscopy. The unsaturated chains of M. oleifera seed oil were found to comprise only mono-unsaturated fatty acids and, in particular, two omega-9 mono-unsaturated acids, (cis-9-octadecenoic (oleic acid) and cis-11-eicosenoic acids) and one omega-7 mono-unsaturated acid (cis-11-octadecenoic acid (vaccenic acid)). The mono-unsaturated fatty acids were detected as separated resonances in the spectral regions where the carbonyl and olefinic carbons resonate according to the 1,3- and 2-positions on the glycerol backbone. The unambiguous detection of vaccenic acid was also achieved through the resonance of the omega-3 carbon. The (13)C NMR methodology enabled the simultaneous detection of oleate, vaccenate, and eicosenoate chains according to their positions on the glycerol backbone (1,3- and 2-positions) through the carboxyl, olefinic, and methylene envelope carbons of the triacylglycerol acyl chains. PMID:11853466

  10. FT-IR spectroscopy characterization of schwannoma: a case study

    NASA Astrophysics Data System (ADS)

    Ferreira, Isabelle; Neto, Lazaro P. M.; das Chagas, Maurilio José; Carvalho, Luís. Felipe C. S.; dos Santos, Laurita; Ribas, Marcelo; Loddi, Vinicius; Martin, Airton A.

    2016-03-01

    Schwannoma are rare benign neural neoplasia. The clinical diagnosis could be improved if novel optical techniques are performed. Among these techniques, FT-IR is one of the currently techniques which has been applied for samples discrimination using biochemical information with minimum sample preparation. In this work, we report a case of a schwannoma in the cervical region. A histological examination described a benign process. An immunohistochemically examination demonstrated positivity to anti-S100 protein antibody, indicating a diagnosis of schwannoma. The aim of this analysis was to characterize FT-IR spectrum of the neoplastic and normal tissue in the fingerprint (1000-1800 cm-1) and high wavenumber region (2800-3600 cm-1). The IR spectra were collect from tumor tissue and normal nerve samples by a FT-IR spectrophotometer (Spotlight Perkin Elmer 400, USA) with 64 scans, and resolution of 4 cm-1. A total of twenty spectra were recorded (10 from schwannoma and 10 from nerve). Multivariate Analysis was used to classify the data. Through average and standard deviation analysis we observed that the main spectral change occurs at ≍1600 cm-1 (amide I) and ≍1400 cm-1 (amide III) in the fingerprint region, and in CH2/CH3 protein-lipids and OH-water vibrations for the high wavenumber region. In conclusion, FT-IR could be used as a technique for schwannoma analysis helping to establish specific diagnostic.

  11. Completely automated open-path FT-IR spectrometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Atmospheric analysis by open-path Fourier transform infrared (OP/FT-IR) spectrometry has been possible for over two decades but has not been widely used because of the limitations of the software of commercial instruments. In this paper, we describe the current state-of-the-art of the hardware and s...

  12. Bonded Cumomer Analysis of Human Melanoma Metabolism Monitored by 13C NMR Spectroscopy of Perfused Tumor Cells.

    PubMed

    Shestov, Alexander A; Mancuso, Anthony; Lee, Seung-Cheol; Guo, Lili; Nelson, David S; Roman, Jeffrey C; Henry, Pierre-Gilles; Leeper, Dennis B; Blair, Ian A; Glickson, Jerry D

    2016-03-01

    A network model for the determination of tumor metabolic fluxes from (13)C NMR kinetic isotopomer data has been developed and validated with perfused human DB-1 melanoma cells carrying the BRAF V600E mutation, which promotes oxidative metabolism. The model generated in the bonded cumomer formalism describes key pathways of tumor intermediary metabolism and yields dynamic curves for positional isotopic enrichment and spin-spin multiplets. Cells attached to microcarrier beads were perfused with 26 mm [1,6-(13)C2]glucose under normoxic conditions at 37 °C and monitored by (13)C NMR spectroscopy. Excellent agreement between model-predicted and experimentally measured values of the rates of oxygen and glucose consumption, lactate production, and glutamate pool size validated the model. ATP production by glycolytic and oxidative metabolism were compared under hyperglycemic normoxic conditions; 51% of the energy came from oxidative phosphorylation and 49% came from glycolysis. Even though the rate of glutamine uptake was ∼ 50% of the tricarboxylic acid cycle flux, the rate of ATP production from glutamine was essentially zero (no glutaminolysis). De novo fatty acid production was ∼ 6% of the tricarboxylic acid cycle flux. The oxidative pentose phosphate pathway flux was 3.6% of glycolysis, and three non-oxidative pentose phosphate pathway exchange fluxes were calculated. Mass spectrometry was then used to compare fluxes through various pathways under hyperglycemic (26 mm) and euglycemic (5 mm) conditions. Under euglycemic conditions glutamine uptake doubled, but ATP production from glutamine did not significantly change. A new parameter measuring the Warburg effect (the ratio of lactate production flux to pyruvate influx through the mitochondrial pyruvate carrier) was calculated to be 21, close to upper limit of oxidative metabolism. PMID:26703469

  13. Intermolecular Interactions in Crystalline Theobromine as Reflected in Electron Deformation Density and (13)C NMR Chemical Shift Tensors.

    PubMed

    Bouzková, Kateřina; Babinský, Martin; Novosadová, Lucie; Marek, Radek

    2013-06-11

    An understanding of the role of intermolecular interactions in crystal formation is essential to control the generation of diverse crystalline forms which is an important concern for pharmaceutical industry. Very recently, we reported a new approach to interpret the relationships between intermolecular hydrogen bonding, redistribution of electron density in the system, and NMR chemical shifts (Babinský et al. J. Phys. Chem. A, 2013, 117, 497). Here, we employ this approach to characterize a full set of crystal interactions in a sample of anhydrous theobromine as reflected in (13)C NMR chemical shift tensors (CSTs). The important intermolecular contacts are identified by comparing the DFT-calculated NMR CSTs for an isolated theobromine molecule and for clusters composed of several molecules as selected from the available X-ray diffraction data. Furthermore, electron deformation density (EDD) and shielding deformation density (SDD) in the proximity of the nuclei involved in the proposed interactions are calculated and visualized. In addition to the recently reported observations for hydrogen bonding, we focus here particularly on the stacking interactions. Although the principal relations between the EDD and CST for hydrogen bonding (HB) and stacking interactions are similar, the real-space consequences are rather different. Whereas the C-H···X hydrogen bonding influences predominantly and significantly the in-plane principal component of the (13)C CST perpendicular to the HB path and the C═O···H hydrogen bonding modulates both in-plane components of the carbonyl (13)C CST, the stacking modulates the out-of-plane electron density resulting in weak deshielding (2-8 ppm) of both in-plane principal components of the CST and weak shielding (∼ 5 ppm) of the out-of-plane component. The hydrogen-bonding and stacking interactions may add to or subtract from one another to produce total values observed experimentally. On the example of theobromine, we demonstrate

  14. Identification of aquatically available carbon from algae through solution-state NMR of whole (13)C-labelled cells.

    PubMed

    Akhter, Mohammad; Dutta Majumdar, Rudraksha; Fortier-McGill, Blythe; Soong, Ronald; Liaghati-Mobarhan, Yalda; Simpson, Myrna; Arhonditsis, George; Schmidt, Sebastian; Heumann, Hermann; Simpson, André J

    2016-06-01

    Green algae and cyanobacteria are primary producers with profound impact on food web functioning. Both represent key carbon sources and sinks in the aquatic environment, helping modulate the dissolved organic matter balance and representing a potential biofuel source. Underlying the impact of algae and cyanobacteria on an ecosystem level is their molecular composition. Herein, intact (13)C-labelled whole cell suspensions of Chlamydomonas reinhardtii, Chlorella vulgaris and Synechocystis were studied using a variety of 1D and 2D (1)H/(13)C solution-state nuclear magnetic resonance (NMR) spectroscopic experiments. Solution-state NMR spectroscopy of whole cell suspensions is particularly relevant as it identifies species that are mobile (dissolved or dynamic gels), 'aquatically available' and directly contribute to the aquatic carbon pool upon lysis, death or become a readily available food source on consumption. In this study, a wide range of metabolites and structural components were identified within the whole cell suspensions. In addition, significant differences in the lipid/triacylglyceride (TAG) content of green algae and cyanobacteria were confirmed. Mobile species in algae are quite different from those in abundance in 'classic' dissolved organic matter (DOM) indicating that if algae are major contributors to DOM, considerable selective preservation of minor components (e.g. sterols) or biotransformation would have to occur. Identifying the metabolites and dissolved components within algal cells by NMR permits future studies of carbon transfer between species and through the food chain, whilst providing a foundation to better understand the role of algae in the formation of DOM and the sequestration/transformation of carbon in aquatic environments. PMID:27074782

  15. Identification of aquatically available carbon from algae through solution-state NMR of whole (13)C-labelled cells.

    PubMed

    Akhter, Mohammad; Dutta Majumdar, Rudraksha; Fortier-McGill, Blythe; Soong, Ronald; Liaghati-Mobarhan, Yalda; Simpson, Myrna; Arhonditsis, George; Schmidt, Sebastian; Heumann, Hermann; Simpson, André J

    2016-06-01

    Green algae and cyanobacteria are primary producers with profound impact on food web functioning. Both represent key carbon sources and sinks in the aquatic environment, helping modulate the dissolved organic matter balance and representing a potential biofuel source. Underlying the impact of algae and cyanobacteria on an ecosystem level is their molecular composition. Herein, intact (13)C-labelled whole cell suspensions of Chlamydomonas reinhardtii, Chlorella vulgaris and Synechocystis were studied using a variety of 1D and 2D (1)H/(13)C solution-state nuclear magnetic resonance (NMR) spectroscopic experiments. Solution-state NMR spectroscopy of whole cell suspensions is particularly relevant as it identifies species that are mobile (dissolved or dynamic gels), 'aquatically available' and directly contribute to the aquatic carbon pool upon lysis, death or become a readily available food source on consumption. In this study, a wide range of metabolites and structural components were identified within the whole cell suspensions. In addition, significant differences in the lipid/triacylglyceride (TAG) content of green algae and cyanobacteria were confirmed. Mobile species in algae are quite different from those in abundance in 'classic' dissolved organic matter (DOM) indicating that if algae are major contributors to DOM, considerable selective preservation of minor components (e.g. sterols) or biotransformation would have to occur. Identifying the metabolites and dissolved components within algal cells by NMR permits future studies of carbon transfer between species and through the food chain, whilst providing a foundation to better understand the role of algae in the formation of DOM and the sequestration/transformation of carbon in aquatic environments.

  16. Characterization of alkyl carbon in forest soils by CPMAS 13C NMR spectroscopy and dipolar dephasing

    USGS Publications Warehouse

    Kogel-Knabner, I.; Hatcher, P.G.

    1989-01-01

    Samples obtained from forest soils at different stages of decomposition were treated sequentially with chloroform/methanol (extraction of lipids), sulfuric acid (hydrolysis), and sodium chlorite (delignification) to enrich them in refractory alkyl carbon. As revealed by NMR spectroscopy, this treatment yielded residues with high contents of alkyl carbon. In the NMR spectra of residues obtained from litter samples, resonances for carbohydrates are also present, indicating that these carbohydrates are tightly bound to the alkyl carbon structures. During decomposition in the soils this resistant carbohydrate fraction is lost almost completely. In the litter samples the alkyl carbon shows a dipolar dephasing behavior indicative of two structural components, a rigid and a more mobile component. As depth and decomposition increase, only the rigid component is observed. This fact could be due to selective degradation of the mobile component or to changes in molecular mobility during decomposition, e.g., because of an increase in cross linking or contact with the mineral matter of the soil.

  17. 13C MAS NMR studies of crystalline cholesterol and lipid mixtures modeling atherosclerotic plaques.

    PubMed Central

    Guo, W; Hamilton, J A

    1996-01-01

    Cholesterol and cholesteryl esters are the predominant lipids of atherosclerotic plaques. To provide fundamental data for the quantitative study of plaque lipids in situ, crystalline cholesterol (CHOL) and CHOL/cholesteryl ester (CE) mixtures with other lipids were studied by solid-state nuclear magnetic resonance with magic-angle-sample spinning. Highly distinctive spectra for three different crystalline structures of CHOL were obtained. When CHOL crystals were mixed with isotropic CE oil, solubilized CHOL (approximately 13 mol % CHOL) was detected by characteristic resonances such as C5, C6, and C3; the excess crystalline CHOL (either anhydrous or monohydrate) remained in its original crystalline structure, without being affected by the coexisting CE. By use of 13C-enriched CHOL, the solubility of CHOL in the CE liquid-crystalline phase (approximately 8 mol %) was measured. When phosphatidylcholine was hydrated in presence of CHOL and CE, magic-angle-sampling nuclear magnetic resonance revealed liquid-crystalline CHOL/phosphatidylcholine multilayers with approximately an equal molar ratio of CHOL/phosphatidylcholine. Excess CHOL existed in the monohydrate crystalline form, and CE in separate oil or crystalline phases, depending on the temperature. The magic-angle-sampling nuclear magnetic resonance protocol for identifying different lipid phases was applied to intact (ex vivo) atherosclerotic plaques of cholesterol-fed rabbits. Liquid, liquid-crystalline, and solid phases of CE were characterized. Images FIGURE 2 PMID:8913623

  18. Substituent effects in the 13C NMR chemical shifts of alpha-mono-substituted acetonitriles.

    PubMed

    Reis, Adriana K C A; Rittner, Roberto

    2007-03-01

    13C chemical shifts empirical calculations, through a very simple additivity relationship, for the alpha-methylene carbon of some alpha-mono-substituted acetonitriles, Y-CH(2)-CN (Y=H, F, Cl, Br, I, OMe, OEt, SMe, SEt, NMe(2), NEt(2), Me and Et), lead to similar, or even better, results in comparison to the reported values obtained through Quantum Mechanics methods. The observed deviations, for some substituents, are very similar for both approaches. This divergence between experimental and calculated, either empirically or theoretically, values are smaller than for the corresponding acetones, amides, acetic acids and methyl esters, which had been named non-additivity effects (or intramolecular interaction chemical shifts, ICS) and attributed to some orbital interactions. Here, these orbital interactions do not seem to be the main reason for the non-additivity effects in the empirical calculations, which must be due solely to the magnetic anisotropy of the heavy atom present in the substituent. These deviations, which were also observed in the theoretical calculations, were attributed in that case to the non-inclusion of relativistic effects and spin-orbit coupling in the Hamiltonian. Some divergence is also observed for the cyano carbon chemical shifts, probably due to the same reasons.

  19. Plant Resources, (13)C-NMR Spectral Characteristic and Pharmacological Activities of Dammarane-Type Triterpenoids.

    PubMed

    Ruan, Jingya; Zheng, Chang; Qu, Lu; Liu, Yanxia; Han, Lifeng; Yu, Haiyang; Zhang, Yi; Wang, Tao

    2016-01-01

    Dammarane-type triterpenoids (DTT) widely distribute in various medicinal plants. They have generated a great amount of interest in the field of new drug research and development. Generally, DTT are the main bioactive ingredients abundant in Araliaceae plants, such as Panax ginseng, P. japonicas, P. notoginseng, and P. quinquefolium. Aside from Araliaceae, DTT also distribute in other families, including Betulaceae, Cucurbitaceae, Meliaceae, Rhamnaceae, and Scrophulariaceae. Until now, about 136 species belonging to 46 families have been reported to contain DTT. In this article, the genus classifications of plant sources of the botanicals that contain DTT are reviewed, with particular focus on the NMR spectral features and pharmacological activities based on literature reports, which may be benefit for the development of new drugs or food additives. PMID:27529202

  20. Recent applications of /sup 13/C NMR spectroscopy to biological systems

    SciTech Connect

    Matwiyoff, N.A.

    1981-01-01

    Carbon-13 nuclear magnetic resonance (NMR) spectroscopy, in conjunction with carbon-13 labelling, is a powerful new analytical technique for the study of metabolic pathways and structural components in intact organelles, cells, and tissues. The technique can provide, rapidly and non-destructively, unique information about: the architecture and dynamics of structural components; the nature of the intracellular environment; and metabolic pathways and relative fluxes of individual carbon atoms. With the aid of results recently obtained by us and those reported by a number of other laboratories, the problems and potentialities of the technique will be reviewed with emphasis on: the viscosities of intracellular fluids; the structure and dynamics of the components of membranes; and the primary and secondary metabolic pathways of carbon in microorganisms, plants, and mammalian cells in culture.

  1. Molecular composition of recycled organic wastes, as determined by solid-state {sup 13}C NMR and elemental analyses

    SciTech Connect

    Eldridge, S.M.; Chen, C.R.; Xu, Z.H.; Nelson, P.N.; Boyd, S.E.; Meszaros, I.; Chan, K.Y.

    2013-11-15

    Highlights: • Model estimated the molecular C components well for most RO wastes. • Molecular nature of organic matter in RO wastes varied widely. • Molecular composition by NMR modelling preferable to extraction techniques. • Some model shortcomings in estimating molecular composition of biochars. • Waste molecular composition important for carbon/nutrient outcomes in soil. - Abstract: Using solid state {sup 13}C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes.

  2. Hydration properties of regioselectively etherified celluloses monitored by 2H and 13C solid-state MAS NMR spectroscopy.

    PubMed

    Larsen, Flemming H; Schöbitz, Michael; Schaller, Jens

    2012-06-20

    The hydration properties of 2,3-O-hydroxypropylcellulose (HPC) and 2,3-O-hydroxyethylcellulose (HEC) were analyzed by multi-nuclear solid-state MAS NMR spectroscopy. By 13C single-pulse (SP) MAS and cross-polarization (CP) MAS NMR, differences between the immobile regions and all parts of the polysaccharides were detected as a function of hydration. Complementary information about the water environments was observed by 2H MAS NMR. By this approach it was demonstrated that side chains in 2,3-O-HPC and 2,3-O-HEC were easier to hydrate than the cellulose backbone. Furthermore the motion of water was more restricted (slower) in 2,3-O-HPC than in 2,3-O-HEC. For both polysaccharides the hydration could be explained by a two-step process: in step one increased ordering of the immobile regions occurs after which the entire polymer is hydrated in step two.

  3. Quantitative (13)C Solid-State NMR Spectra by Multiple-Contact Cross-polarization for Drug Delivery: From Active Principles to Excipients and Drug Carriers.

    PubMed

    Saïdi, Fadila; Taulelle, Francis; Martineau, Charlotte

    2016-08-01

    In this contribution, we present an analysis of the main parameters influencing the efficiency of the (1)H → (13)C multiple-contact cross-polarization nuclear magnetic resonance (NMR) experiment in the context of solid pharmaceutical materials. Using the optimum experimental conditions, quantitative (13)C NMR spectra are then obtained for porous metal-organic frameworks (potential drug carriers) and for components present in drug formulations (active principle ingredient and excipients, amorphous or crystalline). Finally, we show that mixtures of components can also be quantified with this method and, hence, that it represents an ideal tool for quantification of pharmaceutical formulations by (13)C cross-polarization under magic-angle spinning NMR in the industry as it is robust and easy to set up, much faster than direct (13)C polarization and is efficient for samples at natural abundance. PMID:27372550

  4. 1H and 13C NMR signal assignment of cucurbitacin derivatives from Citrullus colocynthis (L.) Schrader and Ecballium elaterium L. (Cucurbitaceae).

    PubMed

    Seger, Christoph; Sturm, Sonja; Mair, Maria-Elisabeth; Ellmerer, Ernst P; Stuppner, Hermann

    2005-06-01

    2D NMR-derived 1H and 13C NMR signal assignments of six structurally closely related cucurbitacin derivatives are presented. The investigated 2-O-beta-D-glucopyranosylcucurbitacins I, J, K, and L were obtained from Citrullus colocynthis (L.) Schrader whereas the aglyca cucurbitacin E and I were isolated from Ecballium elaterium L.

  5. FT-IR Microspectroscopy of Rat Ear Cartilage

    PubMed Central

    Vidal, Benedicto de Campos; Mello, Maria Luiza S.

    2016-01-01

    Rat ear cartilage was studied using Fourier transform-infrared (FT-IR) microspectroscopy to expand the current knowledge which has been established for relatively more complex cartilage types. Comparison of the FT-IR spectra of the ear cartilage extracellular matrix (ECM) with published data on articular cartilage, collagen II and 4-chondroitin-sulfate standards, as well as of collagen type I-containing dermal collagen bundles (CBs) with collagen type II, was performed. Ear cartilage ECM glycosaminoglycans (GAGs) were revealed histochemically and as a reduction in ECM FT-IR spectral band heights (1140–820 cm-1) after testicular hyaluronidase digestion. Although ear cartilage is less complex than articular cartilage, it contains ECM components with a macromolecular orientation as revealed using polarization microscopy. Collagen type II and GAGs, which play a structural role in the stereo-arrangement of the ear cartilage, contribute to its FT-IR spectrum. Similar to articular cartilage, ear cartilage showed that proteoglycans add a contribution to the collagen amide I spectral region, a finding that does not recommend this region for collagen type II quantification purposes. In contrast to articular cartilage, the symmetric stretching vibration of –SO3- groups at 1064 cm-1 appeared under-represented in the FT-IR spectral profile of ear cartilage. Because the band corresponding to the asymmetric stretching vibration of –SO3- groups (1236–1225 cm-1) overlapped with that of amide III bands, it is not recommended for evaluation of the –SO3- contribution to the FT-IR spectrum of the ear cartilage ECM. Instead, a peak (or shoulder) at 1027–1016 cm-1 could be better considered for this intent. Amide I/amide II ratios as calculated here and data from the literature suggest that protein complexes of the ear cartilage ECM are arranged with a lower helical conformation compared to pure collagen II. The present results could motivate further studies on this tissue

  6. FT-IR Microspectroscopy of Rat Ear Cartilage.

    PubMed

    Vidal, Benedicto de Campos; Mello, Maria Luiza S

    2016-01-01

    Rat ear cartilage was studied using Fourier transform-infrared (FT-IR) microspectroscopy to expand the current knowledge which has been established for relatively more complex cartilage types. Comparison of the FT-IR spectra of the ear cartilage extracellular matrix (ECM) with published data on articular cartilage, collagen II and 4-chondroitin-sulfate standards, as well as of collagen type I-containing dermal collagen bundles (CBs) with collagen type II, was performed. Ear cartilage ECM glycosaminoglycans (GAGs) were revealed histochemically and as a reduction in ECM FT-IR spectral band heights (1140-820 cm-1) after testicular hyaluronidase digestion. Although ear cartilage is less complex than articular cartilage, it contains ECM components with a macromolecular orientation as revealed using polarization microscopy. Collagen type II and GAGs, which play a structural role in the stereo-arrangement of the ear cartilage, contribute to its FT-IR spectrum. Similar to articular cartilage, ear cartilage showed that proteoglycans add a contribution to the collagen amide I spectral region, a finding that does not recommend this region for collagen type II quantification purposes. In contrast to articular cartilage, the symmetric stretching vibration of -SO3- groups at 1064 cm-1 appeared under-represented in the FT-IR spectral profile of ear cartilage. Because the band corresponding to the asymmetric stretching vibration of -SO3- groups (1236-1225 cm-1) overlapped with that of amide III bands, it is not recommended for evaluation of the -SO3- contribution to the FT-IR spectrum of the ear cartilage ECM. Instead, a peak (or shoulder) at 1027-1016 cm-1 could be better considered for this intent. Amide I/amide II ratios as calculated here and data from the literature suggest that protein complexes of the ear cartilage ECM are arranged with a lower helical conformation compared to pure collagen II. The present results could motivate further studies on this tissue under

  7. Electronic states and molecular dynamics of single-component molecular conductors [M (tmdt) 2] (M =Ni , Pt) studied by 13C and 1H NMR

    NASA Astrophysics Data System (ADS)

    Takagi, Rina; Miyagawa, Kazuya; Yoshimura, Masahide; Gangi, Hiro; Kanoda, Kazushi; Zhou, Biao; Idobata, Yuki; Kobayashi, Akiko

    2016-01-01

    The molecular conductors [M(tmdt) 2] (M =Ni , Pt) consisting of single molecular species are investigated with 13C NMR and 1H NMR. The temperature dependences of the 13C NMR shift and relaxation rate provide microscopic evidence for the metallic nature with appreciable electron correlations. Both compounds exhibit an anomalous frequency-dependent enhancement in the 1H nuclear spin-lattice relaxation rate in a wide temperature range. These observations signify the presence of extraordinary molecular motions with low energy excitations.

  8. Complete assignments of (1)H and (13)C NMR data for two 3beta,8beta-epoxymexicanolides from the fruit of a Chinese mangrove Xylocarpus granatum.

    PubMed

    Wu, Jun; Xiao, Zhihui; Song, Yang; Zhang, Si; Xiao, Qiang; Ma, Cha; Ding, Haixin; Li, Qingxin

    2006-01-01

    Three 3beta,8beta-epoxymexicanolides, including xyloccensin K, 6-acetoxycedrodorin and a new one named xyloccensin W, were isolated from the fruit of a Chinese mangrove Xylocarpus granatum. Their structures were determined by spectroscopic analyses. The first complete assignment of (1)H and (13)C NMR data for xyloccensin W was achieved by means of 2D NMR techniques, including (1)H-(1)H COSY, HSQC, HMBC and NOESY spectra. In addition, the confusion of (1)H and (13)C NMR data previously reported for xyloccensin K was clarified.

  9. 13C and 1H chemical shift assignments and conformation confirmation of trimedlure-Y via 2-D NMR

    NASA Astrophysics Data System (ADS)

    Warthen, J. D.; Waters, R. M.; McGovern, T. P.

    The conformation of 1,1-dimethylethyl 5-chloro- cis-2-methylcyclohexane-1-carboxylate (trimedlure-Y) was confirmed as 1,2,5 equatorial, axial, equatorial via 13C, 1H, APT, CSCM and COSY NMR analyses. The carbon and proton nuclei in trimedlure-Y and the previously unassigned eight cyclohexyl protons (1.50-2.60 ppm) in 1,1-dimethylethyl 5-chloro- trans-2-methylcyclohexane-1-carboxylate (trimedlure-B 1; 1,2,5 equatorial, equatorial, equatorial) were also characterized by these methods. The effects of the 2-CH 3 in the axial or equatorial conformation upon the chemical shifts of the other nuclei in the molecule are discussed.

  10. 13C direct detected COCO-TOCSY: A tool for sequence specific assignment and structure determination in protonless NMR experiments

    NASA Astrophysics Data System (ADS)

    Balayssac, Stéphane; Jiménez, Beatriz; Piccioli, Mario

    2006-10-01

    A novel experiment is proposed to provide inter-residue sequential correlations among carbonyl spins in 13C detected, protonless NMR experiments. The COCO-TOCSY experiment connects, in proteins, two carbonyls separated from each other by three, four or even five bonds. The quantitative analysis provides structural information on backbone dihedral angles ϕ as well as on the side chain dihedral angles of Asx and Glx residues. This is the first dihedral angle constraint that can be obtained via a protonless approach. About 75% of backbone carbonyls in Calbindin D 9K, a 75 aminoacid dicalcium protein, could be sequentially connected via a COCO-TOCSY spectrum. 49 3J values were measured and related to backbone ϕ angles. Structural information can be extended to the side chain orientation of aminoacids containing carbonyl groups. Additionally, long range homonuclear coupling constants, 4JCC and 5JCC, could be measured. This constitutes an unprecedented case for proteins of medium and small size.

  11. Brominated Compounds from Marine Sponges of the Genus Aplysina and a Compilation of Their 13C NMR Spectral Data

    PubMed Central

    Lira, Narlize Silva; Montes, Ricardo Carneiro; Tavares, Josean Fechine; da Silva, Marcelo Sobral; da Cunha, Emidio V. L.; de Athayde-Filho, Petronio Filgueiras; Rodrigues, Luis Cezar; da Silva Dias, Celidarque; Barbosa-Filho, Jose Maria

    2011-01-01

    Aplysina is the best representative genus of the family Aplysinidae. Halogenated substances are its main class of metabolites. These substances contribute greatly to the chemotaxonomy and characterization of the sponges belonging to this genus. Due to their pharmacological activities, these alkaloids are of special interest. The chemistry of halogenated substances and of the alkaloids has long been extensively studied in terrestrial organisms, while the number of marine organisms studied has just started to increase in the last decades. This review describes 101 halogenated substances from 14 species of Aplysina from different parts of the world. These substances can be divided into the following classes: bromotyramines (A), cavernicolins (B), hydroverongiaquinols (C), bromotyrosineketals (D), bromotyrosine lactone derivatives (E), oxazolidones (F), spiroisoxazolines (G), verongiabenzenoids (H), verongiaquinols (I), and dibromocyclohexadienes (J). A compilation of their 13C NMR data is also part of the review. For this purpose 138 references were consulted. PMID:22163189

  12. Investigation of gamma-irradiated vegetable seeds with high-resolution solid-state 13C NMR.

    PubMed

    Bardet, Michel; Maron, Sébastien; Foray, Marie Françoise; Berger, Maurice; Guillermo, Armel

    2004-04-01

    13C solid-state NMR was used to investigate the effects of gamma radiation on vegetable seeds, Pisum sativum and Latuca sativa, at absorbed doses that inhibit their germination. By combining single-pulse excitation and cross-polarization experiments under magic angle spinning, both liquid and solid domains of seeds can be characterized. We showed that the liquid domains, mostly made of triacylglycerols (TAG), of vegetable seeds are not sensitive to radiation. The main structural changes have been observed in the embryonic axes of seeds when the seeds are water-imbibed before irradiation. These results rule out a starting hypothesis concerning the potential role of TAG contained in oil bodies as a potential source of aldehydes that could further react with DNA moiety.

  13. Quantification of taxanes in a leaf and twig extract from Taxus baccata L. using 13C NMR spectroscopy.

    PubMed

    Paoli, Mathieu; Bighelli, Ange; Castola, Vincent; Tomi, Félix; Casanova, Joseph

    2013-11-01

    In the course of our ongoing work on the chemical characterization of Taxus baccata L. growing wild in Corsica, we have developed and validated a method for direct quantification of taxane derivatives by (13)C NMR using 10-deacetylbaccatin III as reference compound and 1,6-hexanediol as internal standard. We have observed good accuracy (relative errors between 0.3% and 3.5%), linearity (R(2) = 0.999) and precision (reproducibility 8.5 mg ± 1.1%) of the measurements. The experimental procedure was applied to the quantification of six identified taxanes in a fraction of chromatography of a methanol extract of T. baccata leaves. This method can be applied to other compounds bearing the taxane skeleton.

  14. Enantiomeric differentiation of oxygenated p-menthane derivatives by 13C NMR using Yb(hfc)3.

    PubMed

    Lanfranchi, Don Antoine; Blanc, Marie-Cécile; Vellutini, Muriel; Bradesi, Pascale; Casanova, Joseph; Tomi, Félix

    2008-12-01

    The (13)C NMR behaviour of 21 p-menthanic terpene bearing an oxygenated function (alcohol, ketone, acetate) was examined in the presence of a chiral lanthanide shift reagent (Yb(hfc)(3)). For each monocyclic compound, we measured the lanthanide-induced shift (LIS) on the signals of the carbons and the splitting of signals allowing the enantiomeric differentiation. Some general features were found about their LIS behaviour: experimental data establishing distinct patterns for carvomenthone-like compounds and menthone-like compounds. The enantiomeric splitting was observed for the majority of signals in the spectrum of each compound. In the case of alcohols and acetates, the influence of the relative stereochemistry (cis vs trans) of isopropyl(ene) and the binding function was discussed.

  15. Identification of Li-Ion Battery SEI Compounds through (7)Li and (13)C Solid-State MAS NMR Spectroscopy and MALDI-TOF Mass Spectrometry.

    PubMed

    Huff, Laura A; Tavassol, Hadi; Esbenshade, Jennifer L; Xing, Wenting; Chiang, Yet-Ming; Gewirth, Andrew A

    2016-01-13

    Solid-state (7)Li and (13)C MAS NMR spectra of cycled graphitic Li-ion anodes demonstrate SEI compound formation upon lithiation that is followed by changes in the SEI upon delithiation. Solid-state (13)C DPMAS NMR shows changes in peaks associated with organic solvent compounds (ethylene carbonate and dimethyl carbonate, EC/DMC) upon electrochemical cycling due to the formation of and subsequent changes in the SEI compounds. Solid-state (13)C NMR spin-lattice (T1) relaxation time measurements of lithiated Li-ion anodes and reference poly(ethylene oxide) (PEO) powders, along with MALDI-TOF mass spectrometry results, indicate that large-molecular-weight polymers are formed in the SEI layers of the discharged anodes. MALDI-TOF MS and NMR spectroscopy results additionally indicate that delithiated anodes exhibit a larger number of SEI products than is found in lithiated anodes. PMID:26653886

  16. Temperature dependence of the folding and unfolding kinetics of the GCN4 leucine zipper via 13C(alpha)-NMR.

    PubMed Central

    Holtzer, M E; Bretthorst, G L; d'Avignon, D A; Angeletti, R H; Mints, L; Holtzer, A

    2001-01-01

    Studies by one-dimensional NMR are reported on the interconversion of folded and unfolded forms of the GCN4 leucine zipper in neutral saline buffer. The peptide bears 99% 13C(alpha) labels at three sites: V9, L12, and G31. Time-domain 13C(alpha)-NMR spectra are interpreted by global Bayesian lineshape analysis to extract the rate constants for both unfolding and folding as functions of temperature in the range 47-71 degrees C. The data are well fit by the assumption that the same rate constants apply at each labeled site, confirming that only two conformational states need be considered. Results show that 1) both processes require a free energy of activation; 2) unfolding is kinetically enthalpy-opposed and entropy-driven, while folding is the opposite; and 3) the transition state dimer ensemble averages approximately 40% helical. The activation parameters for unfolding, derived from NMR data at the elevated temperatures where both conformations are populated, lead to estimates of the rate constant at low temperatures (5-15 degrees C) that agree with extant values determined by stopped-flow CD via dilution from denaturing media. However, the corresponding estimated values for the folding rate constant are larger by two to three orders of magnitude than those obtained by stopped flow. We propose that this apparent disagreement is caused by the necessity, in the stopped-flow experiment, for initiation of new helices as the highly denaturant-unfolded molecule adjusts to the newly created benign solvent conditions. This must reduce the success rate of collisions in producing the folded molecule. In the NMR determinations, however, the unfolded chains always have a small, but essential, helix content that makes such initiation unnecessary. Support for this hypothesis is adduced from recent extant experiments on the helix-coil transition in single-chain helical peptides and from demonstration that the folding rate constants for coiled coils, as obtained by stopped flow

  17. Effects of osmotic stress on Methanococcus thermolithotrophicus: 13C-edited 1H-NMR studies of osmolyte turnover.

    PubMed

    Ciulla, R A; Roberts, M F

    1999-04-19

    In vivo NMR studies of the thermophilic archaeon Methanococcus thermolithotrophicus, with sodium formate as the substrate for methanogenesis, were used to monitor formate utilization, methane production, and osmolyte pool synthesis and turnover under different conditions. The rate of formate conversion to CO2 and H2 decreased for cells adapted to higher external NaCl, consistent with the slower doubling times for cells adapted to high external NaCl. However, when cells grown at one NaCl concentration were resuspended at a different NaCl, formate utilization rates increased. Production of methane from 13C pools varied little with external NaCl in nonstressed culture, but showed larger changes when cells were osmotically shocked. In the absence of osmotic stress, all three solutes used for osmotic balance in these cells, l-alpha-glutamate, beta-glutamate, and Nepsilon-acetyl-beta-lysine, had 13C turnover rates that increased with external NaCl concentration. Upon hyperosmotic stress, there was a net synthesis of alpha-glutamate (over a 30-min time-scale) with smaller amounts of beta-glutamate and little if any of the zwitterion Nepsilon-acetyl-beta-lysine. This is a marked contrast to adapted growth in high NaCl where Nepsilon-acetyl-beta-lysine is the dominant osmolyte. Hypoosmotic shock selectively enhanced beta-glutamate and Nepsilon-acetyl-beta-lysine turnover. These results are discussed in terms of the osmoadaptation strategies of M. thermolithotrophicus.

  18. FT-IR spectroscopy of lipoproteins—A comparative study

    NASA Astrophysics Data System (ADS)

    Krilov, Dubravka; Balarin, Maja; Kosović, Marin; Gamulin, Ozren; Brnjas-Kraljević, Jasminka

    2009-08-01

    FT-IR spectra, in the frequency region 4000-600 cm -1, of four major lipoprotein classes: very low density lipoprotein (VLDL), low density lipoprotein (LDL) and two subclasses of high density lipoproteins (HDL 2 and HDL 3) were analyzed to obtain their detailed spectral characterization. Information about the protein domain of particle was obtained from the analysis of amide I band. The procedure of decomposition and curve fitting of this band confirms the data already known about the secondary structure of two different apolipoproteins: apo A-I in HDL 2 and HDL 3 and apo B-100 in LDL and VLDL. For information about the lipid composition and packing of the particular lipoprotein the well expressed lipid bands in the spectra were analyzed. Characterization of spectral details in the FT-IR spectrum of natural lipoprotein is necessary to study the influence of external compounds on its structure.

  19. Applications of FT-IR spectrophotometry in cancer diagnostics.

    PubMed

    Bunaciu, Andrei A; Hoang, Vu Dang; Aboul-Enein, Hassan Y

    2015-01-01

    This review provides a brief background to the application of infrared spectroscopy, including Fourier transform-infrared spectroscopy, in biological fluids. It is not meant to be complete or exhaustive but to provide the reader with sufficient background for selected applications in cancer diagnostics. Fourier transform-infrared spectroscopy (FT-IR) is a fast and nondestructive analytical method. The infrared spectrum of a mixture serves as the basis to quantitate its constituents, and a number of common clinical chemistry tests have proven to be feasible using this approach. This review focuses on biomedical FT-IR applications, published in the period 2009-2013, used for early detection of cancer through qualitative and quantitative analysis.

  20. FT-IR microscopy imaging on oral cavity tumours, II

    NASA Astrophysics Data System (ADS)

    Conti, C.; Giorgini, E.; Pieramici, T.; Rubini, C.; Tosi, G.

    2005-06-01

    Changes in the biochemistry of oral cavity tissues have been studied by FT-IR microscopy. Various aspects of squamous cell carcinomas of cheek mucosa, of tongue, of gingiva, and of the floor of the mouth have been analyzed through FT-IR imaging with the aim to relate spectral patterns with histopathological results. In particular, changes in frequency and intensity of proteins, connective and nucleic acids vibrational modes as well as the visualization of biochemical single wavenumber or band ratio images allowed a quali- and quantitative evaluation of the changes in the proliferating activity from displastic to neoplastic states. 'Supervised' and 'unsupervised' procedures of data handling afforded a satisfactory degree of accordance between spectroscopic and histological findings.

  1. Fourier Transform Infrared Spectroscopy: Part II. Advantages of FT-IR.

    ERIC Educational Resources Information Center

    Perkins, W. D.

    1987-01-01

    This is Part II in a series on Fourier transform infrared spectroscopy (FT-IR). Described are various advantages of FT-IR spectroscopy including energy advantages, wavenumber accuracy, constant resolution, polarization effects, and stepping at grating changes. (RH)

  2. Probing lipid-cholesterol interactions in DOPC/eSM/Chol and DOPC/DPPC/Chol model lipid rafts with DSC and (13)C solid-state NMR.

    PubMed

    Fritzsching, Keith J; Kim, Jihyun; Holland, Gregory P

    2013-08-01

    The interaction between cholesterol (Chol) and phospholipids in bilayers was investigated for the ternary model lipid rafts, DOPC/eSM/Chol and DOPC/DPPC/Chol, with differential scanning calorimetry (DSC) and (13)C cross polarization magic angle spinning (CP-MAS) solid-state NMR. The enthalpy and transition temperature (Tm) of the Lα liquid crystalline phase transition from DSC was used to probe the thermodynamics of the different lipids in the two systems as a function of Chol content. The main chain (13)C (CH2)n resonance is resolved in the (13)C CP-MAS NMR spectra for the unsaturated (DOPC) and saturated (eSM or DPPC) chain lipid in the ternary lipid raft mixtures. The (13)C chemical shift of this resonance can be used to detect differences in chain ordering and overall interactions with Chol for the different lipid constituents in the ternary systems. The combination of DSC and (13)C CP-MAS NMR results indicate that there is a preferential interaction between SM and Chol below Tm for the DOPC/eSM/Chol system when the Chol content is ≤20mol%. In contrast, no preferential interaction between Chol and DPPC is observed in the DOPC/DPPC/Chol system above or below Tm. Finally, (13)C CP-MAS NMR resolves two Chol environments in the DOPC/eSM/Chol system below Tm at Chol contents >20mol% while, a single Chol environment is observed for DOPC/DPPC/Chol at all compositions.

  3. Phenotypic Expression in Wheat Revealed Using FT-IR Microspectroscopy

    SciTech Connect

    Brewer, L.; Wetzel, D

    2009-01-01

    Wheat selected for cultivation through the centuries has a glume that is 'soft' instead of 'tough' as naturally occurring. In production, this is desirable because it enables mechanical threshing with efficient separation of kernel from the head of each stalk without damaging the kernel. FT-IR microspectroscopy provides chemically based, objective assessment of genetic expression by measuring the extent of genetic expression. In the Microbeam Molecular Spectroscopy Laboratory, Manhattan, KS, an imaging FT-IR microspectrometer with a detector array focused on the image plane was used to obtain spectral data from dissected glume specimens of nine tough and eleven soft wheat cultivars in a rectangular mapping pattern. With cellulose as the substrate, the extent of lignification is measurable from the ratio of the lignin (1508 cm{sup -1}) baseline adjusted band area to the representative cellulosic (1370 cm{sup -1}) band area. A distinction between soft and tough glumes is obtained in numerical terms. Using a band ratio minimizes variation due to thickness differences. While analyzing mapped sections of glume, care is taken to avoid tabulation of spectral data from vascular bundles. Inclusion of these data would to avoid tabulation of spectral data from vascular bundles. Inclusion of these data would bias the analysis toward the composition of highly lignified vascular bundles. Spatially resolved focal plane array FT-IR microspectroscopy reveals the extent of glume lignification that is coincident with the toughness trait. This enables breeders to rank the degree of lignin expression and discriminate between soft and tough breeding results.

  4. Characterization and identification of microorganisms by FT-IR microspectrometry

    NASA Astrophysics Data System (ADS)

    Ngo-Thi, N. A.; Kirschner, C.; Naumann, D.

    2003-12-01

    We report on a novel FT-IR approach for microbial characterization/identification based on a light microscope coupled to an infrared spectrometer which offers the possibility to acquire IR-spectra of microcolonies containing only few hundred cells. Microcolony samples suitable for FT-IR microspectroscopic measurements were obtained by a replica technique with a stamping device that transfers spatially accurate cells of microcolonies growing on solid culture plates to a special, IR-transparent or reflecting stamping plate. High quality spectra could be recorded either by applying the transmission/absorbance or the reflectance/absorbance mode of the infrared microscope. Signal to noise ratios higher than 1000 were obtained for microcolonies as small as 40 μm in diameter. Reproducibility levels were established that allowed species and strain identification. The differentiation and classification capacity of the FT-IR microscopic technique was tested for different selected microorganisms. Cluster and factor analysis methods were used to evaluate the complex spectral data. Excellent discrimination between bacteria and yeasts, and at the same time Gram-negative and Gram-positive bacterial strains was obtained. Twenty-two selected strains of different species within the genus Staphylococcus were repetitively measured and could be grouped into correct species cluster. Moreover, the results indicated that the method allows also identifications at the subspecies level. Additionally, the new approach allowed spectral mapping analysis of single colonies which provided spatially resolved characterization of growth heterogeneity within complex microbial populations such as colonies.

  5. A novel approach to the rapid assignment of (13)C NMR spectra of major components of vegetable oils such as avocado, mango kernel and macadamia nut oils.

    PubMed

    Retief, Liezel; McKenzie, Jean M; Koch, Klaus R

    2009-09-01

    Assignment of (13)C nuclear magnetic resonance (NMR) spectra of major fatty acid components of South African produced vegetable oils was attempted using a method in which the vegetable oil was spiked with a standard triacylglycerol. This proved to be inadequate and therefore a new rapid and potentially generic graphical linear correlation method is proposed for assignment of the (13)C NMR spectra of major fatty acid components of apricot kernel, avocado pear, grapeseed, macadamia nut, mango kernel and marula vegetable oils. In this graphical correlation method, chemical shifts of fatty acids present in a known standard triacylglycerol is plotted against the corresponding chemical shifts of fatty acids present in the vegetable oils. This new approach (under carefully defined conditions and concentrations) was found especially useful for spectrally crowded regions where significant peak overlap occurs and was validated with the well-known (13)C NMR spectrum of olive oil which has been extensively reported in the literature. In this way, a full assignment of the (13)C{1H} NMR spectra of the vegetable oils, as well as tripalmitolein was readily achieved and the resonances belonging to the palmitoleic acid component of the triacylglycerols in the case of macadamia nut and avocado pear oil resonances were also assigned for the first time in the (13)C NMR spectra of these oils.

  6. A novel approach to the rapid assignment of (13)C NMR spectra of major components of vegetable oils such as avocado, mango kernel and macadamia nut oils.

    PubMed

    Retief, Liezel; McKenzie, Jean M; Koch, Klaus R

    2009-09-01

    Assignment of (13)C nuclear magnetic resonance (NMR) spectra of major fatty acid components of South African produced vegetable oils was attempted using a method in which the vegetable oil was spiked with a standard triacylglycerol. This proved to be inadequate and therefore a new rapid and potentially generic graphical linear correlation method is proposed for assignment of the (13)C NMR spectra of major fatty acid components of apricot kernel, avocado pear, grapeseed, macadamia nut, mango kernel and marula vegetable oils. In this graphical correlation method, chemical shifts of fatty acids present in a known standard triacylglycerol is plotted against the corresponding chemical shifts of fatty acids present in the vegetable oils. This new approach (under carefully defined conditions and concentrations) was found especially useful for spectrally crowded regions where significant peak overlap occurs and was validated with the well-known (13)C NMR spectrum of olive oil which has been extensively reported in the literature. In this way, a full assignment of the (13)C{1H} NMR spectra of the vegetable oils, as well as tripalmitolein was readily achieved and the resonances belonging to the palmitoleic acid component of the triacylglycerols in the case of macadamia nut and avocado pear oil resonances were also assigned for the first time in the (13)C NMR spectra of these oils. PMID:19544589

  7. Molecular composition of recycled organic wastes, as determined by solid-state 13C NMR and elemental analyses.

    PubMed

    Eldridge, S M; Chen, C R; Xu, Z H; Nelson, P N; Boyd, S E; Meszaros, I; Chan, K Y

    2013-11-01

    Using solid state (13)C NMR data and elemental composition in a molecular mixing model, we estimated the molecular components of the organic matter in 16 recycled organic (RO) wastes representative of the major materials generated in the Sydney basin area. Close correspondence was found between the measured NMR signal intensities and those predicted by the model for all RO wastes except for poultry manure char. Molecular nature of the organic matter differed widely between the RO wastes. As a proportion of organic C, carbohydrate C ranged from 0.07 to 0.63, protein C from <0.01 to 0.66, lignin C from <0.01 to 0.31, aliphatic C from 0.09 to 0.73, carbonyl C from 0.02 to 0.23, and char C from 0 to 0.45. This method is considered preferable to techniques involving imprecise extraction methods for RO wastes. Molecular composition data has great potential as a predictor of RO waste soil carbon and nutrient outcomes.

  8. In situ measurement of magnesium carbonate formation from CO2 using static high-pressure and -temperature 13C NMR.

    PubMed

    Surface, J Andrew; Skemer, Philip; Hayes, Sophia E; Conradi, Mark S

    2013-01-01

    We explore a new in situ NMR spectroscopy method that possesses the ability to monitor the chemical evolution of supercritical CO(2) in relevant conditions for geological CO(2) sequestration. As a model, we use the fast reaction of the mineral brucite, Mg(OH)(2), with supercritical CO(2) (88 bar) in aqueous conditions at 80 °C. The in situ conversion of CO(2) into metastable and stable carbonates is observed throughout the reaction. After more than 58 h of reaction, the sample was depressurized and analyzed using in situ Raman spectroscopy, where the laser was focused on the undisturbed products through the glass reaction tube. Postreaction, ex situ analysis was performed on the extracted and dried products using Raman spectroscopy, powder X-ray diffraction, and magic-angle spinning (1)H-decoupled (13)C NMR. These separate methods of analysis confirmed a spatial dependence of products, possibly caused by a gradient of reactant availability, pH, and/or a reaction mechanism that involves first forming hydroxy-hydrated (basic, hydrated) carbonates that convert to the end-product, anhydrous magnesite. This carbonation reaction illustrates the importance of static (unmixed) reaction systems at sequestration-like conditions. PMID:22676479

  9. (13)C-detected NMR experiments for automatic resonance assignment of IDPs and multiple-fixing SMFT processing.

    PubMed

    Dziekański, Paweł; Grudziąż, Katarzyna; Jarvoll, Patrik; Koźmiński, Wiktor; Zawadzka-Kazimierczuk, Anna

    2015-06-01

    Intrinsically disordered proteins (IDPs) have recently attracted much interest, due to their role in many biological processes, including signaling and regulation mechanisms. High-dimensional (13)C direct-detected NMR experiments have proven exceptionally useful in case of IDPs, providing spectra with superior peak dispersion. Here, two such novel experiments recorded with non-uniform sampling are introduced, these are 5D HabCabCO(CA)NCO and 5D HNCO(CA)NCO. Together with the 4D (HACA)CON(CA)NCO, an extension of the previously published 3D experiments (Pantoja-Uceda and Santoro in J Biomol NMR 59:43-50, 2014. doi: 10.1007/s10858-014-9827-1), they form a set allowing for complete and reliable resonance assignment of difficult IDPs. The processing is performed with sparse multidimensional Fourier transform based on the concept of restricting (fixing) some of spectral dimensions to a priori known resonance frequencies. In our study, a multiple-fixing method was developed, that allows easy access to spectral data. The experiments were tested on a resolution-demanding alpha-synuclein sample. Due to superior peak dispersion in high-dimensional spectrum and availability of the sequential connectivities between four consecutive residues, the overwhelming majority of resonances could be assigned automatically using the TSAR program. PMID:25902761

  10. (1)H and (13)C NMR assignments for five anthraquinones from the mangrove endophytic fungus Halorosellinia sp. (No. 1403).

    PubMed

    Xia, Xue-Kui; Huang, Hua-Rong; She, Zhi-Gang; Shao, Chang-Lun; Liu, Fan; Cai, Xiao-Ling; Vrijmoed, L L P; Lin, Yong-Cheng

    2007-11-01

    We report the unambiguous assignments of the (1)H and (13)C NMR spectra of two new natural products, namely, 1,4,5,6,7,9-hexahydroxy-2-methoxy-7-methyl-5beta,9beta,8abeta, 6alpha,10aalpha-hexahydroanthracen-10 (10aH)-one (1) and 1,4,6-trihydroxy-2-methoxy-7-methylanthracene-9, 10-dione (2), together with three known anthraquinones. These compounds were all isolated from the marine endophytic fungus No. 1403 collected from the South China Sea. Compounds 3 and 4 were isolated from the marine fungus for the first time. The structures were elucidated by the spectroscopic methods 1D and 2D NMR including COSY, HMQC, HMBC and NOE, and HREIMS. In our cytotoxicity assays, compound 5 showed cytotoxicity toward KB and KBv-200 cells with IC(50) of 1.40 and 2.58 microg/ml, respectively. In addition, the plausible biogenic relationship of compounds 1, 2, 3 and 4 is discussed.

  11. 13C MAS NMR evidence for a homogeneously ordered environment of tyrosine M210 in reaction centres of Rhodobacter sphaeroides

    NASA Astrophysics Data System (ADS)

    Shochat, S.; Gast, P.; Hoff, A. J.; Boender, G. J.; van Leeuwen, S.; van Liemt, W. B. S.; Vijgenboom, E.; Raap, J.; Lugtenburg, J.; de Groot, H. J. M.

    1995-01-01

    The initial electron transfer time in the photosynthetic reaction centre of Rhodobacter sphaeroides is highly sensitive to the replacement of tyrosine M210 by a tryptophan residue. Low-temperature magic angle spinning 13C NMR is used to study Rhodobacter sphaeroides 2.4.1 (M)Y210W mutant reaction centres that are labelled with [4'- 13C]tyrosine. The response of (M)Y210 in R26 is assigned unambiguously to the most upfield narrow signal (linewidth 34 Hz) at σi = 152.2 ppm, in the region where non-hydrogen bonded tyrosine signals are expected. From the comparison with the signal of labelled R26 it follows that the chemical environment of the (M)Y210 label is unique. The Y(M)210 is in a structurally and electrostatically homogeneous region on the sensitivity scale of the MAS NMR technique. The environment of M210 is structurally stable and the observation of a narrow line shows that the (M)Y210 side chain can be considered static with respect to rotational diffusion on time scales as long as 10 -2s. The narrow signals from the remaining labels in the protein interior for the 2.4.1 (M)Y210W mutant are remarkably similar to those observed for R26. Using a commonly accepted ratio of 150 ppm shift per positive charge equivalent for aromatic carbons, the chemical shift differences between mutant and R26 translate into small variations of the order of 10 -3 electronic equivalents of charge polarization. Also the linewidths are similar, except for a narrow response at σi = 156.4 ppm that sharpens slightly in the (M)Y210W mutant. Thus, the influence of the (M)Y210W mutation on the global electrostatic properties and structure of the protein, as probed by the tyrosine labels, is minimal. This strongly argues against an explanation of slow and non-exponential electron transfer kinetics in the (M)Y210W RC in terms of loss of structural integrity upon mutation. In contrast, the NMR results strongly support current opinions that (M)Y210 contributes to the fine-tuning of the

  12. A simple mathematical model and practical approach for evaluating citric acid cycle fluxes in perfused rat hearts by 13C-NMR and 1H-NMR spectroscopy.

    PubMed

    Tran-Dinh, S; Hoerter, J A; Mateo, P; Bouet, F; Herve, M

    1997-04-15

    We propose a simple mathematical model and a practical approach for evaluating the flux constant and the absolute value of flux in the citric acid cycle in perfused organs by 13C-NMR and 1H-NMR spectroscopy. We demonstrate that 13C-NMR glutamate spectra are independent of the relative sizes of the mitochondrial and cytosolic compartments and the exchange rates of glutamates, unless there is a difference in 13C chemical shifts of glutamate carbons between the two compartments. Wistar rat hearts (five beating and four KCl-arrested hearts) were aerobically perfused with 100% enriched [2-(13)C]acetate and the kinetics of glutamate carbon labeling from perchloric acid extracts were studied at various perfusion times. Under our experimental conditions, the citric acid cycle flux constant, which represents the fraction of glutamate in exchange with the citric acid cycle per unit time, is about 0.350 +/- 0.003 min(-1) for beating hearts and 0.0741 +/- 0.004 min(-1) for KCl-arrested hearts. The absolute values of the citric acid flux for beating hearts and for KCl-arrested hearts are 1.06 +/- 0.06 micromol x min(-1) x mg(-1) and 0.21 +/- 0.02 micromol x min(-1) x g(-1), respectively. The fraction of unlabeled acetate determined from the proton signal of the methyl group is small and essentially the same in beating and arrested hearts (7.4 +/- 1.7% and 8.8 +/- 2.1%, respectively). Thus, the large difference in the Glu C2/C4 between beating and arrested hearts is not due to the important contribution from anaplerotic sources in arrested hearts but simply to a substantial difference in citric acid cycle fluxes. Our model fits the experimental data well, indicating a fast exchange between 2-oxoglutarate and glutamate in the mitochondria of rat hearts. Analysis of the flux constant, calculated from the half-time of glutamate C4 labeling given in the literature, allows for a comparison of the citric acid flux for various working conditions in different animal species.

  13. The mobility of chondroitin sulfate in articular and artificial cartilage characterized by 13C magic-angle spinning NMR spectroscopy.

    PubMed

    Scheidt, Holger A; Schibur, Stephanie; Magalhães, Alvicler; de Azevedo, Eduardo R; Bonagamba, Tito J; Pascui, Ovidiu; Schulz, Ronny; Reichert, Detlef; Huster, Daniel

    2010-06-01

    We have studied the molecular dynamics of one of the major macromolecules in articular cartilage, chondroitin sulfate. Applying (13)C high-resolution magic-angle spinning NMR techniques, the NMR signals of all rigid macromolecules in cartilage can be suppressed, allowing the exclusive detection of the highly mobile chondroitin sulfate. The technique is also used to detect the chondroitin sulfate in artificial tissue-engineered cartilage. The tissue-engineered material that is based on matrix producing chondrocytes cultured in a collagen gel should provide properties as close as possible to those of the natural cartilage. Nuclear relaxation times of the chondroitin sulfate were determined for both tissues. Although T(1) relaxation times are rather similar, the T(2) relaxation in tissue-engineered cartilage is significantly shorter. This suggests that the motions of chondroitin sulfate in natural and artificial cartilage are different. The nuclear relaxation times of chondroitin sulfate in natural and tissue-engineered cartilage were modeled using a broad distribution function for the motional correlation times. Although the description of the microscopic molecular dynamics of the chondroitin sulfate in natural and artificial cartilage required the identical broad distribution functions for the correlation times of motion, significant differences in the correlation times of motion that are extracted from the model indicate that the artificial tissue does not fully meet the standards of the natural ideal. This could also be confirmed by macroscopic biomechanical elasticity measurements. Nevertheless, these results suggest that NMR is a useful tool for the investigation of the quality of artificially engineered tissue. PMID:20091673

  14. Photo-CIDNP 13C magic angle spinning NMR on bacterial reaction centres: exploring the electronic structure of the special pair and its surroundings.

    PubMed

    Matysik, J; Schulten, E; Alia; Gast, P; Raap, J; Lugtenburg, J; Hoff, A J; de Groot, H J

    2001-08-01

    Photochemically induced dynamic nuclear polarisation (photo-CIDNP) in intact bacterial reaction centres has been observed by 13C-solid state NMR under continuous illumination with white light. Strong intensity enhancement of 13C NMR signals of the aromatic rings allows probing the electronic ground state of the two BChl cofactors of the special pair at the molecular scale with atomic selectivity. Differences between the two BChl cofactors are discussed. Several aliphatic 13C atoms of cofactors, as well as 13C atoms of the imidazole ring of histidine residue(s), show nuclear-spin polarisation to the same extent as the aromatic nuclei of the cofactors. Mechanisms and applications of polarisation transfer are discussed. PMID:11592409

  15. Multidimensional High-Resolution Magic Angle Spinning and Solution-State NMR Characterization of (13)C-labeled Plant Metabolites and Lignocellulose.

    PubMed

    Mori, Tetsuya; Tsuboi, Yuuri; Ishida, Nobuhiro; Nishikubo, Nobuyuki; Demura, Taku; Kikuchi, Jun

    2015-01-01

    Lignocellulose, which includes mainly cellulose, hemicellulose, and lignin, is a potential resource for the production of chemicals and for other applications. For effective production of materials derived from biomass, it is important to characterize the metabolites and polymeric components of the biomass. Nuclear magnetic resonance (NMR) spectroscopy has been used to identify biomass components; however, the NMR spectra of metabolites and lignocellulose components are ambiguously assigned in many cases due to overlapping chemical shift peaks. Using our (13)C-labeling technique in higher plants such as poplar samples, we demonstrated that overlapping peaks could be resolved by three-dimensional NMR experiments to more accurately assign chemical shifts compared with two-dimensional NMR measurements. Metabolites of the (13)C-poplar were measured by high-resolution magic angle spinning NMR spectroscopy, which allows sample analysis without solvent extraction, while lignocellulose components of the (13)C-poplar dissolved in dimethylsulfoxide/pyridine solvent were analyzed by solution-state NMR techniques. Using these methods, we were able to unambiguously assign chemical shifts of small and macromolecular components in (13)C-poplar samples. Furthermore, using samples of less than 5 mg, we could differentiate between two kinds of genes that were overexpressed in poplar samples, which produced clearly modified plant cell wall components. PMID:26143886

  16. Multidimensional High-Resolution Magic Angle Spinning and Solution-State NMR Characterization of 13C-labeled Plant Metabolites and Lignocellulose

    PubMed Central

    Mori, Tetsuya; Tsuboi, Yuuri; Ishida, Nobuhiro; Nishikubo, Nobuyuki; Demura, Taku; Kikuchi, Jun

    2015-01-01

    Lignocellulose, which includes mainly cellulose, hemicellulose, and lignin, is a potential resource for the production of chemicals and for other applications. For effective production of materials derived from biomass, it is important to characterize the metabolites and polymeric components of the biomass. Nuclear magnetic resonance (NMR) spectroscopy has been used to identify biomass components; however, the NMR spectra of metabolites and lignocellulose components are ambiguously assigned in many cases due to overlapping chemical shift peaks. Using our 13C-labeling technique in higher plants such as poplar samples, we demonstrated that overlapping peaks could be resolved by three-dimensional NMR experiments to more accurately assign chemical shifts compared with two-dimensional NMR measurements. Metabolites of the 13C-poplar were measured by high-resolution magic angle spinning NMR spectroscopy, which allows sample analysis without solvent extraction, while lignocellulose components of the 13C-poplar dissolved in dimethylsulfoxide/pyridine solvent were analyzed by solution-state NMR techniques. Using these methods, we were able to unambiguously assign chemical shifts of small and macromolecular components in 13C-poplar samples. Furthermore, using samples of less than 5 mg, we could differentiate between two kinds of genes that were overexpressed in poplar samples, which produced clearly modified plant cell wall components. PMID:26143886

  17. Synthesis of D-[U-{sup 13}C]Glucal, D-[U-{sup 13}C] Galactal, and L-[U-{sup 13}C]Fucose for NMR structure studies of oligosaccharides

    SciTech Connect

    Wu, R.; Unkefer, C.J.; Silks, L.A. III

    1996-12-31

    The role of carbohydrates is well recognized in a variety of important biological phenomena such as cell surface recognition. Recent advances in carbohydrate chemistry, including the development of solid phase synthesis methods, have helped to provide significant quantities of material by offering general protocols for synthesis of well-defined, pure material. However, the study of the solution structure of oligosaccharides by nuclear magnetic resonance techniques have been hampered by the lack of enriched {sup 13}C material. In an effort to help alleviate this situation, we have been interested in the construction of the title compounds from a single economical carbon source, D-[U-{sup 13}C]glucose. Details of the syntheses will be provided.

  18. Comprehensive determination of protein tyrosine pKa values for photoactive yellow protein using indirect 13C NMR spectroscopy.

    PubMed

    Oktaviani, Nur Alia; Pool, Trijntje J; Kamikubo, Hironari; Slager, Jelle; Scheek, Ruud M; Kataoka, Mikio; Mulder, Frans A A

    2012-02-01

    Upon blue-light irradiation, the bacterium Halorhodospira halophila is able to modulate the activity of its flagellar motor and thereby evade potentially harmful UV radiation. The 14 kDa soluble cytosolic photoactive yellow protein (PYP) is believed to be the primary mediator of this photophobic response, and yields a UV/Vis absorption spectrum that closely matches the bacterium's motility spectrum. In the electronic ground state, the para-coumaric acid (pCA) chromophore of PYP is negatively charged and forms two short hydrogen bonds to the side chains of Glu-46 and Tyr-42. The resulting acid triad is central to the marked pH dependence of the optical-absorption relaxation kinetics of PYP. Here, we describe an NMR approach to sequence-specifically follow all tyrosine side-chain protonation states in PYP from pH 3.41 to 11.24. The indirect observation of the nonprotonated (13)C(γ) resonances in sensitive and well-resolved two-dimensional (13)C-(1)H spectra proved to be pivotal in this effort, as observation of other ring-system resonances was hampered by spectral congestion and line-broadening due to ring flips. We observe three classes of tyrosine residues in PYP that exhibit very different pK(a) values depending on whether the phenolic side chain is solvent-exposed, buried, or hydrogen-bonded. In particular, our data show that Tyr-42 remains fully protonated in the pH range of 3.41-11.24, and that pH-induced changes observed in the photocycle kinetics of PYP cannot be caused by changes in the charge state of Tyr-42. It is therefore very unlikely that the pCA chromophore undergoes changes in its electrostatic interactions in the electronic ground state. PMID:22325281

  19. Thermal unfolding in a GCN4-like leucine zipper: 13C alpha NMR chemical shifts and local unfolding curves.

    PubMed Central

    Holtzer, M E; Lovett, E G; d'Avignon, D A; Holtzer, A

    1997-01-01

    13C alpha chemical shifts and site-specific unfolding curves are reported for 12 sites on a 33-residue, GCN4-like leucine zipper peptide (GCN4-lzK), ranging over most of the chain and sampling most heptad positions. Data were derived from NMR spectra of nine synthetic, isosequential peptides bearing 99% 13C alpha at sites selected to avoid spectral overlap in each peptide. At each site, separate resonances appear for unfolded and folded forms, and most sites show resonances for two folded forms near room temperature. The observed chemical shifts suggest that 1) urea-unfolded GCN4-lzK chains are randomly coiled; 2) thermally unfolded chains include significant transient structure, except at the ends; 3) the coiled-coli structure in the folded chains is atypical near the C-terminus; 4) only those interior sites surrounded by canonical interchain salt bridges fail to show two folded forms. Local unfolding curves, obtained from integrated resonance intensities, show that 1) sites differ in structure content and in melting temperature, so the equilibrium population must comprise more than two molecular conformations; 2) there is significant end-fraying, even at the lowest temperatures, but thermal unfolding is not a progressive unwinding from the ends; 3) residues 9-16 are in the lowest melting region; 4) heptad position does not dictate stability; 5) significant unfolding occurs below room temperature, so the shallow, linear decline in backbone CD seen there has conformational significance. It seems that only a relatively complex array of conformational states could underlie these findings. PMID:9251820

  20. Synthetic, Infrared And Nmr (1H And 13C) Spectral Studies Of N-(Substituted Phenyl)-Methanesulphonamides

    NASA Astrophysics Data System (ADS)

    Jayalakshmi, K. L.; Gowda, B. Thimme

    2004-08-01

    Twenty two N-(substituted phenyl)-methanesulphonamides of the general formula, CH3SO2NHR, where R = 4-XC6H4(X = H, CH3, F, Cl, Br or NO2), i-XC6H4(X=CH3, Cl orNO2 and i=2 or 3) and i, j-X2C6H3(i, j-X2 = 2,3-(CH3)2, 2,4-(CH3)2, 2,5-(CH3)2, 2,6-(CH3)2, 3,5-(CH3)2, 2,3-Cl2, 2,4- Cl2, 2,5-Cl2, 2,6-Cl2 or 3,4-Cl2) were prepared, characterized and their infrared spectra in the solid state and the NMR (1H and 13C) spectra in solution studied. The N-H stretching vibrations absorb in the range, 3298 - 3232 cm-1. Asymmetric and symmetric SO2 stretching vibrations appear as strong absorptions in the ranges, 1331 - 1317 cm-1 and 1157 - 1139 cm-1, respectively. The sulphonamides exhibit S-N stretching vibrations in the range, 926 - 833 cm-1. The effect of substitution in the phenyl ring in terms of electron withdrawing and electron donating groups is non-systematic. The 1H and 13C chemical shifts of N-(substituted phenyl)-methanesulphonamides are assigned to various protons and carbons of the compounds. Further, incremental shifts of the ring protons and carbons due to CH3SO2- and CH3SO2NH- groups in the N-(phenyl)-methanesulphonamide are computed and used to calculate the 1H and 13C chemical shifts of various protons and carbons of N-(substituted phenyl)-methanesulphonamides, by adding substituent contributions to the corresponding aromatic proton or carbon chemical shifts of either aniline, substituted anilines, benzene or substituted benzenes, in different ways, as per the principle of substituent addition. The computed values by different procedures agree well with each other and with the experimental chemical shifts. The correlation of these incremental shifts with the Hammett substituent parameters is poor.

  1. Methyl [13C]glucopyranosiduronic acids: effect of COOH ionization and exocyclic structure on NMR spin-couplings.

    PubMed

    Zhang, Wenhui; Hu, Xiaosong; Carmichael, Ian; Serianni, Anthony S

    2012-11-01

    Methyl α- and β-D-glucopyranuronides singly labeled with (13)C at C1-C6 were prepared from the corresponding (13)C-labeled methyl D-glucopyranosides, and multiple NMR J-couplings (J(HH), J(CH), and J(CC)) were measured in their protonated and ionized forms in aqueous ((2)H(2)O) solution. Solvated density functional theory (DFT) calculations of J-couplings in structurally related model compounds were performed to determine how well the calculated J-couplings matched the experimental values in saccharides bearing an ionizable substituent. Intraring J(HH) values in both uronide anomers, including (3)J(H4,H5), are unaffected by solution pD, and COOH ionization exerts little effect on J(CH) and J(CC) except for (1)J(C1,H1), (1)J(C4,H4), (1)J(C5,H5), (1)J(C5,C6), and (2)J(C3,C5), where changes of up to 5 Hz were observed. Some of these changes are associated with changes in bond lengths upon ionization; in general, better agreement between theory and experiment was observed for couplings less sensitive to exocyclic C-O bond conformation. Titration of (1)H and (13)C chemical shifts, and some J-couplings, yielded a COOH pK(a) of 3.0 ± 0.1 in both anomers. DFT calculations suggest that substituents proximal to the exocyclic COOH group (i.e., the C4-O4 bond) influence the activation barrier to C5-C6 bond rotation due to transient intramolecular H-bonding. A comparison of J-couplings in the glucopyranuronides to corresponding J-couplings in the glucopyranosides showed that more pervasive changes occur upon conversion from a COOH to a CH(2)OH substituent at C6 than from COOH ionization within the uronides. Twelve J-couplings are affected, with the largest being (1)J(C5,C6) (∼18 Hz larger in the uronides), followed by (2)J(C6,H5) (∼2.5 Hz more negative in the uronides).

  2. Characterization of pyrogenic organic matter by 2-dimenstional HETeronucleus CORelation solid-state 13C NMR (HETCOR) spectroscopy

    NASA Astrophysics Data System (ADS)

    Knicker, Heike

    2016-04-01

    technique was used for monitoring the chemical changes occurring during charring of biomass derived from model compounds, fire-affected and unaffected NOM. The 2D 13C HETCOR NMR spectrum of the fire- unaffected soils revealed that most of the carboxyl C occurs as ester or amide. Aside from cross peaks typically seen in spectra of NOM, the spectrum of the respective fire-affected counterpart shows additional signals assignable to PyOM.

  3. Glycerin-Induced Conformational Changes in Bombyx mori Silk Fibroin Film Monitored by 13C CP/MAS NMR and 1H DQMAS NMR

    PubMed Central

    Asakura, Tetsuo; Endo, Masanori; Hirayama, Misaki; Arai, Hiroki; Aoki, Akihiro; Tasei, Yugo

    2016-01-01

    In order to improve the stiff and brittle characteristics of pure Bombyx mori (B. mori) silk fibroin (SF) film in the dry state, glycerin (Glyc) has been used as a plasticizer. However, there have been very limited studies on the structural characterization of the Glyc-blended SF film. In this study, 13C Cross Polarization/Magic Angle Spinning nuclear magnetic resonance (CP/MAS NMR) was used to monitor the conformational changes in the films by changing the Glyc concentration. The presence of only 5 wt % Glyc in the film induced a significant conformational change in SF where Silk I* (repeated type II β-turn and no α-helix) newly appeared. Upon further increase in Glyc concentration, the percentage of Silk I* increased linearly up to 9 wt % Glyc and then tended to be almost constant (30%). This value (30%) was the same as the fraction of Ala residue within the Silk I* form out of all Ala residues of SF present in B. mori mature silkworm. The 1H DQMAS NMR spectra of Glyc-blended SF films confirmed the appearance of Silk I* in the Glyc-blended SF film. A structural model of Glyc-SF complex including the Silk I* form was proposed with the guidance of the Molecular Dynamics (MD) simulation using 1H–1H distance constraints obtained from the 1H Double-Quantum Magic Angle Spinning (DQMAS) NMR spectra. PMID:27618034

  4. Unilateral NMR, 13C CPMAS NMR spectroscopy and micro-analytical techniques for studying the materials and state of conservation of an ancient Egyptian wooden sarcophagus.

    PubMed

    Proietti, Noemi; Presciutti, Federica; Di Tullio, Valeria; Doherty, Brenda; Marinelli, Anna Maria; Provinciali, Barbara; Macchioni, Nicola; Capitani, Donatella; Miliani, Costanza

    2011-03-01

    A multi-technique approach was employed to study a decorated Egyptian wooden sarcophagus (XXV-XXVI dynasty, Third Intermediate Period), belonging to the Museo del Vicino Oriente of the Sapienza University of Rome. Portable non-invasive unilateral NMR was applied to evaluate the conservation state of the sarcophagus. Moreover, using unilateral NMR, a non-invasive analytical protocol was established to detect the presence of organic substances on the surface and/or embedded in the wooden matrix. This protocol allowed for an educated sampling campaign aimed at further investigating the state of degradation of the wood and the presence of organic substances by (13)C cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The composition of the painted layer was analysed by optical microscopy (OM), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), Raman and surface enhanced (resonance) Raman spectroscopy (SERS/SERRS), infrared and GC-MS techniques, evidencing original components such as clay minerals, Egyptian green, indigo, natural gums, and also highlighting restoration pigments and alteration compounds. The identification of the wood, of great value for the reconstruction of the history of the artwork, was achieved by means of optical microscopy.

  5. Glycerin-Induced Conformational Changes in Bombyx mori Silk Fibroin Film Monitored by (13)C CP/MAS NMR and ¹H DQMAS NMR.

    PubMed

    Asakura, Tetsuo; Endo, Masanori; Hirayama, Misaki; Arai, Hiroki; Aoki, Akihiro; Tasei, Yugo

    2016-01-01

    In order to improve the stiff and brittle characteristics of pure Bombyx mori (B. mori) silk fibroin (SF) film in the dry state, glycerin (Glyc) has been used as a plasticizer. However, there have been very limited studies on the structural characterization of the Glyc-blended SF film. In this study, (13)C Cross Polarization/Magic Angle Spinning nuclear magnetic resonance (CP/MAS NMR) was used to monitor the conformational changes in the films by changing the Glyc concentration. The presence of only 5 wt % Glyc in the film induced a significant conformational change in SF where Silk I* (repeated type II β-turn and no α-helix) newly appeared. Upon further increase in Glyc concentration, the percentage of Silk I* increased linearly up to 9 wt % Glyc and then tended to be almost constant (30%). This value (30%) was the same as the fraction of Ala residue within the Silk I* form out of all Ala residues of SF present in B. mori mature silkworm. The ¹H DQMAS NMR spectra of Glyc-blended SF films confirmed the appearance of Silk I* in the Glyc-blended SF film. A structural model of Glyc-SF complex including the Silk I* form was proposed with the guidance of the Molecular Dynamics (MD) simulation using ¹H-¹H distance constraints obtained from the ¹H Double-Quantum Magic Angle Spinning (DQMAS) NMR spectra. PMID:27618034

  6. Improving the accuracy of computed 13C NMR shift predictions by specific environment error correction: fragment referencing.

    PubMed

    Andrews, Keith G; Spivey, Alan C

    2013-11-15

    The accuracy of both Gauge-including atomic orbital (GIAO) and continuous set of gauge transformations (CSGT) (13)C NMR spectra prediction by Density Functional Theory (DFT) at the B3LYP/6-31G** level is shown to be usefully enhanced by employing a 'fragment referencing' method for predicting chemical shifts without recourse to empirical scaling. Fragment referencing refers to a process of reducing the error in calculating a particular NMR shift by consulting a similar molecule for which the error in the calculation is easily deduced. The absolute accuracy of the chemical shifts predicted when employing fragment referencing relative to conventional techniques (e.g., using TMS or MeOH/benzene dual referencing) is demonstrated to be improved significantly for a range of substrates, which illustrates the superiority of the technique particularly for systems with similar chemical shifts arising from different chemical environments. The technique is particularly suited to molecules of relatively low molecular weight containing 'non-standard' magnetic environments, e.g., α to halogen atoms, which are poorly predicted by other methods. The simplicity and speed of the technique mean that it can be employed to resolve routine structural assignment problems that require a degree of accuracy not provided by standard incremental or hierarchically ordered spherical description of environment (HOSE) algorithms. The approach is also demonstrated to be applicable when employing the MP2 method at 6-31G**, cc-pVDZ, aug-cc-pVDZ, and cc-pVTZ levels, although none of these offer advantage in terms of accuracy of prediction over the B3LYP/6-31G** DFT method.

  7. Differentiation of Leishmania species by FT-IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Aguiar, Josafá C.; Mittmann, Josane; Ferreira, Isabelle; Ferreira-Strixino, Juliana; Raniero, Leandro

    2015-05-01

    Leishmaniasis is a parasitic infectious disease caused by protozoa that belong to the genus Leishmania. It is transmitted by the bite of an infected female Sand fly. The disease is endemic in 88 countries Desjeux (2001) [1] (16 developed countries and 72 developing countries) on four continents. In Brazil, epidemiological data show the disease is present in all Brazilian regions, with the highest incidences in the North and Northeast. There are several methods used to diagnose leishmaniasis, but these procedures have many limitations, are time consuming, have low sensitivity, and are expensive. In this context, Fourier Transform Infrared Spectroscopy (FT-IR) analysis has the potential to provide rapid results and may be adapted for a clinical test with high sensitivity and specificity. In this work, FT-IR was used as a tool to investigate the promastigotes of Leishmaniaamazonensis, Leishmaniachagasi, and Leishmaniamajor species. The spectra were analyzed by cluster analysis and deconvolution procedure base on spectra second derivatives. Results: cluster analysis found four specific regions that are able to identify the Leishmania species. The dendrogram representation clearly indicates the heterogeneity among Leishmania species. The band deconvolution done by the curve fitting in these regions quantitatively differentiated the polysaccharides, amide III, phospholipids, proteins, and nucleic acids. L. chagasi and L. major showed a greater biochemistry similarity and have three bands that were not registered in L. amazonensis. The L. amazonensis presented three specific bands that were not recorded in the other two species. It is evident that the FT-IR method is an indispensable tool to discriminate these parasites. The high sensitivity and specificity of this technique opens up the possibilities for further studies about characterization of other microorganisms.

  8. Structure and equilibria of Ca 2+-complexes of glucose and sorbitol from multinuclear ( 1H, 13C and 43Ca) NMR measurements supplemented with molecular modelling calculations

    NASA Astrophysics Data System (ADS)

    Pallagi, A.; Dudás, Cs.; Csendes, Z.; Forgó, P.; Pálinkó, I.; Sipos, P.

    2011-05-01

    Ca 2+-complexation of D-glucose and D-sorbitol have been investigated with the aid of multinuclear ( 1H, 13C and 43Ca) NMR spectroscopy and ab initio quantum chemical calculations. Formation constants of the forming 1:1 complexes have been estimated from one-dimensional 13C NMR spectra obtained at constant ionic strength (1 M NaCl). Binding sites were identified from 2D 1H- 43Ca NMR spectra. 2D NMR measurements and ab initio calculations indicated that Ca 2+ ions were bound in a tridentate manner via the glycosidic OH, the ethereal oxygen in the ring and the OH on the terminal carbon for the α- and β-anomers of glucose and for sorbitol simultaneous binding of four hydroxide moieties (C1, C2, C4 and C6) was suggested.

  9. Effects of insulin on perfused liver from streptozotocin-diabetic and untreated rats: /sup 13/C NMR assay of pyruvate kinase flux

    SciTech Connect

    Cohen, S.M.

    1987-01-27

    The effects of insulin in vitro on perfused liver from streptozotocin-diabetic rats and their untreated littermates during gluconeogenesis from either (3-/sup 13/C)alanine + ethanol or (2-/sup 13/C)pyruvate + NH/sub 4/Cl + ethanol were studied by /sup 13/C NMR. A /sup 13/C NMR determination of the rate of pyruvate kinase flux under steady-state conditions of active gluconeogenesis was developed; this assay includes a check on the reuse of recycled pyruvate. The preparations studied provided gradations of pyruvate kinase flux within the confines of the assay's requirement of active gluconeogenesis. By this determination, the rate of pyruvate kinase flux was 0.74 +/- 0.04 of the gluconeogenic rate in liver from 24-h-fasted controls; in liver from 12-h fasted controls, relative pyruvate kinase flux increased to 1.0 +/- 0.2. In diabetic liver, this flux was undetectable by the authors NMR method. Insulin's hepatic influence in vitro was greatest in the streptozotocin model of type 1 diabetes: upon treatment of diabetic liver with 7 nM insulin in vitro, a partial reversal of many of the differences noted between diabetic and control liver was demonstrated by /sup 13/C NMR. A major effect of insulin in vitro upon diabetic liver was the induction of a large increase in the rate of pyruvate kinase flux, bringing relative and absolute fluxes up to the levels measured in 24-h-fasted controls. By way of comparison, the effects of ischemia on diabetic liver were studied by /sup 13/C NMR to test whether changes in allosteric effectors under these conditions could also increase pyruvate kinase flux. A large increase in this activity was demonstrated in ischemic diabetic liver.

  10. Solid-state NMR studies of theophylline co-crystals with dicarboxylic acids.

    PubMed

    Pindelska, Edyta; Sokal, Agnieszka; Szeleszczuk, Lukasz; Pisklak, Dariusz Maciej; Kolodziejski, Waclaw

    2014-11-01

    In this work, three polycrystalline materials containing co-crystals of theophylline with malonic, maleic, and glutaric acids were studied using (13)C, (15)N and (1)H solid-state NMR and FT-IR spectroscopy. The NMR assignments were supported by gauge including projector augmented waves (GIPAW) calculations of chemical shielding, performed using X-ray determined geometry. The experimental (13)C cross polarization/magic angle spinning (CP/MAS) NMR results and the calculated isotropic chemical shifts were in excellent agreement. A rapid and convenient method for theophylline co-crystals crystal structure analysis has been proposed for co-crystals, which are potentially new APIs.

  11. 13C NMR detects conformational change in the 100-kD membrane transporter ClC-ec1

    PubMed Central

    Abraham, Sherwin J.; Cheng, Ricky C.; Chew, Thomas A.; Khantwal, Chandra M.; Liu, Corey W.; Gong, Shimei; Nakamoto, Robert K.; Maduke, Merritt

    2015-01-01

    CLC transporters catalyze the exchange of Cl- for H+ across cellular membranes. To do so, they must couple Cl- and H+ binding and unbinding to protein conformational change. However, the sole conformational changes distinguished crystallographically are small movements of a glutamate side chain that locally gates the ion-transport pathways. Therefore, our understanding of whether and how global protein dynamics contribute to the exchange mechanism has been severely limited. To overcome the limitations of crystallography, we used solution-state 13C-methyl NMR with labels on methionine, lysine, and engineered cysteine residues to investigate substrate (H+) dependent conformational change outside the restraints of crystallization. We show that methyl labels in several regions report H+-dependent spectral changes. We identify one of these regions as Helix R, a helix that extends from the center of the protein, where it forms the part of the inner gate to the Cl--permeation pathway, to the extracellular solution. The H+-dependent spectral change does not occur when a label is positioned just beyond Helix R, on the unstructured C-terminus of the protein. Together, the results suggest that H+ binding is mechanistically coupled to closing of the intracellular access-pathway for Cl-. PMID:25631353

  12. Determination of the structural changes by Raman and {sup 13}C CP/MAS NMR spectroscopy on native corn starch with plasticizers

    SciTech Connect

    Cozar, O.; Filip, C.; Tripon, C.; Cioica, N.; Coţa, C.; Nagy, E. M.

    2013-11-13

    The plasticizing - antiplasticizing effect of water and glycerol contents on native corn starch samples is investigated by FT-Raman and {sup 13}C CP/MAS NMR spectroscopy. The presence of both amorphous and crystalline structural phases was evidenced in pure native corn starch and also in the samples containing plasticizers. Among the crystalline starch structures, the A- and V- types were suggested by CP/MAS NMR spectra.

  13. Aromatic spectral editing techniques for magic-angle-spinning solid-state NMR spectroscopy of uniformly (13)C-labeled proteins.

    PubMed

    Williams, Jonathan K; Schmidt-Rohr, Klaus; Hong, Mei

    2015-11-01

    The four aromatic amino acids in proteins, namely histidine, phenylalanine, tyrosine, and tryptophan, have strongly overlapping (13)C chemical shift ranges between 100 and 160ppm, and have so far been largely neglected in solid-state NMR determination of protein structures. Yet aromatic residues play important roles in biology through π-π and cation-π interactions. To better resolve and assign aromatic residues' (13)C signals in magic-angle-spinning (MAS) solid-state NMR spectra, we introduce two spectral editing techniques. The first method uses gated (1)H decoupling in a proton-driven spin-diffusion (PDSD) experiment to remove all protonated (13)C signals and retain only non-protonated carbon signals in the aromatic region of the (13)C spectra. The second technique uses chemical shift filters and (1)H-(13)C dipolar dephasing to selectively detect the Cα, Cβ and CO cross peaks of aromatic residues while suppressing the signals of all aliphatic residues. We demonstrate these two techniques on amino acids, a model peptide, and the microcrystalline protein GB1, and show that they significantly simplify the 2D NMR spectra and both reveal and permit the ready assignment of the aromatic residues' signals.

  14. Ab initio study of {sup 13}C NMR chemical shifts for the chromophores of rhodopsin and bacteriorhodopsin. 2. Comprehensive analysis of the {sup 13}C chemical shifts of protonated all-trans-retinylidene Schiff base

    SciTech Connect

    Sakurai, Minoru; Wada, Mitsuhito; Inoue, Yoshio; Tamura, Yusuke; Watanabe, Yoichi

    1996-02-01

    Theoretical analysis was performed for the {sup 13}C chemical shifts of the retinal chromophore in bacteriorhodopsin (bR) by means of ab initio NMR shielding calculation, based on the localized orbital/ local origin method. In order to comprehensively investigate the correlation between the {sup 13}C chemical shieldings of the unsaturated carbons and physicochemical perturbations relating to the spectral tuning of bacteriorhodopsin, the following three factors are taken into account in the present calculation: (1) change in strength of the hydrogen bonding between protonated retinylidene Schiff base and its counterion, (2) conformational changes about single bonds of the conjugated chain, and (3) electrostatic interactions between the Schiff base and electric dipoles. On the basis of these calculations, we successfully find a molecular model for which the shielding calculation almost completely reproduces the observed chemical shift data for the chromophore of bR. 47 refs., 13 figs.

  15. Complete (1)H and (13)C NMR chemical shift assignments of mono-, di-, and trisaccharides as basis for NMR chemical shift predictions of polysaccharides using the computer program casper.

    PubMed

    Roslund, Mattias U; Säwén, Elin; Landström, Jens; Rönnols, Jerk; Jonsson, K Hanna M; Lundborg, Magnus; Svensson, Mona V; Widmalm, Göran

    2011-08-16

    The computer program casper uses (1)H and (13)C NMR chemical shift data of mono- to trisaccharides for the prediction of chemical shifts of oligo- and polysaccharides. In order to improve the quality of these predictions the (1)H and (13)C, as well as (31)P when applicable, NMR chemical shifts of 30 mono-, di-, and trisaccharides were assigned. The reducing sugars gave two distinct sets of NMR resonances due to the α- and β-anomeric forms. In total 35 (1)H and (13)C NMR chemical shift data sets were obtained from the oligosaccharides. One- and two-dimensional NMR experiments were used for the chemical shift assignments and special techniques were employed in some cases such as 2D (1)H,(13)C-HSQC Hadamard Transform methodology which was acquired approximately 45 times faster than a regular t(1) incremented (1)H,(13)C-HSQC experiment and a 1D (1)H,(1)H-CSSF-TOCSY experiment which was able to distinguish spin-systems in which the target protons were only 3.3Hz apart. The (1)H NMR chemical shifts were subsequently refined using total line-shape analysis with the PERCH NMR software. The acquired NMR data were then utilized in the casper program (http://www.casper.organ.su.se/casper/) for NMR chemical shift predictions of the O-antigen polysaccharides from Klebsiella O5, Shigella flexneri serotype X, and Salmonella arizonae O62. The data were compared to experimental data of the polysaccharides from the two former strains and the lipopolysaccharide of the latter strain showing excellent agreement between predicted and experimental (1)H and (13)C NMR chemical shifts.

  16. 1H-13C HSQC NMR spectroscopy for estimating procyanidin/prodelphinidin and cis/trans flavan-3-ol ratios of condensed tannin samples: correlation with thiolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Studies with a diverse array of 22 condensed tannin (CT) fractions from 9 plant species demonstrated that procyanidin/prodelphinidin (PC/PD) and cis/trans flavan-3-ol ratios can be appraised by 1H-13C HSQC NMR. The method was developed from fractions containing 44 to ~100% CT, PC/PD ratios ranging f...

  17. Estimation of procyanidin/prodelphinidin and cis/trans flavanol ratios of condensed tannin fractions by 1H-13C HSQC NMR spectroscopy: Correlation with thiolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Integration of cross-peak contours of H/C-2’,6’ signals from prodelphinidin (PD) and of H/C-6’ signals from procyanidin (PC) units in 1H-13C HSQC nuclear magnetic resonance (NMR) spectra of condensed tannins yielded nuclei-adjusted PC/PD estimates that were highly correlated with PC/PD ratios obtain...

  18. A Discovery-Based Hydrochlorination of Carvone Utilizing a Guided-Inquiry Approach to Determine the Product Structure from [superscript 13]C NMR Spectra

    ERIC Educational Resources Information Center

    Pelter, Michael W.; Walker, Natalie M.

    2012-01-01

    This experiment describes a discovery-based method for the regio- and stereoselective hydrochlorination of carvone, appropriate for a 3-h second-semester organic chemistry laboratory. The product is identified through interpretation of the [superscript 13]C NMR and DEPT spectra are obtained on an Anasazi EFT-60 at 15 MHz as neat samples. A…

  19. Solid state 13C NMR studies of methane dehydroaromatization reaction on Mo/HZSM-5 and W/HZSM-5 catalysts.

    PubMed

    Yang, Jun; Ma, Ding; Deng, Feng; Luo, Qing; Zhang, Mingjin; Bao, Xinhe; Ye, Chaohui

    2002-12-21

    Methane dehydroaromatization on Mo/HZSM-5 and W/HZSM-5 catalysts was studied by solid state 13C NMR spectroscopy, both variation of the state of transition metal component and products such as ethane, benzene, ethene adsorbed on or in zeolite were observed after high temperature (900-1000 K) reaction.

  20. Molecular structure, vibrational and 13C NMR spectra of two ent-kaurenes spirolactone type diterpenoids rabdosinate and rabdosin B: A combined experimental and density functional methods

    NASA Astrophysics Data System (ADS)

    Wang, Tao; Wang, Xueliang

    2015-01-01

    The title compounds, rabdosinate and rabdosin B, were isolated from the leaves of Isodon japonica, and characterized by IR-NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO-13C) chemical shift values of the title compounds have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set. In addition, obtained results were related to the linear regression of experimental 13C NMR chemical shifts values. The integral equation formalism polarized continuum model (IEFPCM) was used in treating chloroform solvation effects on optimized structural parameters and 13C chemical shifts. Besides, molecular electrostatic potential (MEP), HOMO-LUMO analysis were performed by the B3LYP method.

  1. A study of the molecular conformations and the vibrational, 1H and 13C NMR spectra of the anticancer drug tamoxifen and triphenylethylene

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.; Khan, Ibrahim

    2016-08-01

    The structural stability and the vibrational spectra of the anticancer drug tamoxifen and triphenylethylene were investigated by the DFT B3LYP/6-311G (d,p) calculations. Tamoxifen and triphenylethylene were predicted to exist predominantly as non-planar structures. The vibrational frequencies and the 1H and 13C NMR chemical shifts of the low energy structures of tamoxifen and triphenylethylene were computed at the DFT B3LYP level of theory. Complete vibrational assignments were provided by combined theoretical and experimental data of tamoxifen and triphenylethylene. The 1H and 13C NMR spectra of both molecules were interpreted by experimental and DFT calculated chemical shifts of the two molecules. The RMSD between experimental and theoretical 1H and 13C chemical shifts for tamoxifen is 0.29 and 4.72 ppm, whereas for triphenylethylene, it is 0.16 and 2.70 ppm, respectively.

  2. Molecular structure, vibrational and 13C NMR spectra of two ent-kaurenes spirolactone type diterpenoids rabdosinate and rabdosin B: a combined experimental and density functional methods.

    PubMed

    Wang, Tao; Wang, Xueliang

    2015-01-25

    The title compounds, rabdosinate and rabdosin B, were isolated from the leaves of Isodon japonica, and characterized by IR-NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO-13C) chemical shift values of the title compounds have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set. In addition, obtained results were related to the linear regression of experimental 13C NMR chemical shifts values. The integral equation formalism polarized continuum model (IEFPCM) was used in treating chloroform solvation effects on optimized structural parameters and 13C chemical shifts. Besides, molecular electrostatic potential (MEP), HOMO-LUMO analysis were performed by the B3LYP method. PMID:25123947

  3. Molecular structure, vibrational and 13C NMR spectra of two ent-kaurenes spirolactone type diterpenoids rabdosinate and rabdosin B: a combined experimental and density functional methods.

    PubMed

    Wang, Tao; Wang, Xueliang

    2015-01-25

    The title compounds, rabdosinate and rabdosin B, were isolated from the leaves of Isodon japonica, and characterized by IR-NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge including atomic orbital (GIAO-13C) chemical shift values of the title compounds have been calculated by using DFT/B3LYP method with 6-311++G(d,p) basis set. In addition, obtained results were related to the linear regression of experimental 13C NMR chemical shifts values. The integral equation formalism polarized continuum model (IEFPCM) was used in treating chloroform solvation effects on optimized structural parameters and 13C chemical shifts. Besides, molecular electrostatic potential (MEP), HOMO-LUMO analysis were performed by the B3LYP method.

  4. [FTIR and 13C NMR Analysis of Dissolved Organic Matter (DOM) in the Treatment Process of Tannery Wastewater].

    PubMed

    Fan, Chun-hui; Zhang, Ying-chao; Tang, Ze-heng; Wang, Jia-hong

    2015-05-01

    Nowadays, the wastewater quantity discharged yearly from tannery industry is around 0. 2 billion t in China. The contaminants of tannery wastewater include macromolecular organic matters, such as grease, fur scraps and collagen, and the alkaline wastewater appears to be of high content of salt and COD. The quality of tannery wastewater is monitored strictly among all kinds of industry wastewater. In the treatment process of tannery wastewater, the quality of inlet and outlet water is generally analyzed. In fact, the transformation behavior of contaminants should be additionally checked to optimize the treatment conditions. Dissolved organic matter (DOM) is commonly existed in water-bodies and helpful to understand the physicochemical characteristics, while the related work should be further studied on tannery wastewater. The approaches of elemental analysis, thermal gravimetric analysis (TG), Fourier infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (13C NMR) were used to reveal the characteristics of DOM in the treatment process of tannery wastewater. The results showed the carbon content of DOM samples increased gradually, atomic ratios of H/C increased firstly and then decreased, indicating the organic matters were decomposed into chain structures firstly, finally forming the component hard to degraded. The pyrolysis process of DOM mainly proceeded in the regions of 110~530 °C (aliphatic compound, protein, etc. ) and 530~800 °C (aromatic ring, single bond of C-C, etc. ). The functional groups of DOM included -OH, -NH2, C=O and so on, and the aromatic substances were detected, shown from FTIR figures, in the later period of the reaction, caused by the metabolism effect of micro-organism. The content of alkoxy-C increased to the maximum in the second biochemical pond, and the minimum content of aromatic-C appeared in the second biochemical pond, suggesting the transformation behavior of carbon functional groups. The investigation on DOM in tannery

  5. Soil organic degradation: bridging the gap between Rock-Eval pyrolysis and chemical characterization (CPMAS 13C NMR)

    NASA Astrophysics Data System (ADS)

    Albrecht, Remy; Sebag, David; Verrecchia, Eric

    2013-04-01

    Being a source of mineral nutrients, organic matter contributes to soil chemical fertility and acts on soil physical fertility through its role in soil structure. Soil organic matter (SOM) is a key component of soils. Despite the paramount importance of SOM, information on its chemistry and behaviour in soils is incomplete. Numerous methods are used to characterize and monitor OM dynamics in soils using different approaches (Kogel-Knabner, 2000). Two of the main approaches are evaluated and compared in this study. Rock-Eval pyrolysis (RE pyrolysis) provides a description of a SOM's general evolution using its thermal resistance. The second tool (13C CPMAS NMR) aims to give precise and accurate chemical information on OM characterization. The RE pyrolysis technique was designed for petroleum exploration (Lafargue et al., 1998) and because of its simplicity, it has been applied to a variety of other materials such as soils or Recent sediments (Disnar et al., 2000; Sebag, 2006). Recently, RE pyrolysis became a conventional tool to study OM dynamics in soils. In RE pyrolysis, a peak deconvolution is applied to the pyrolysis signal in order to get four main components related to major classes of organic constituents. These components differ in origin and resistance to pyrolysis: labile biological constituents (F1), resistant biological constituents (F2), immature non-biotic constituents (F3) and a mature refractory fraction (F4) (Sebag, 2006; Coppard, 2006). Main advantages of the technique are its repeatability, and rapidity to provide an overview of OM properties and stocks. However, do the four major classes used in the literature reflect a pertinent chemical counterpart? To answer this question, we used 13C Nuclear Magnetic Resonance Spectroscopy in the solid state (13C CPMAS NMR) to collect direct information on structural and conformational characteristics of OM. NMR resonances were assigned to chemical structures according to five dominant forms: alkyl C, O

  6. 1H and 13C NMR assignments for two oxaphenalenones bacillosporin C and D from the mangrove endophytic fungus SBE-14.

    PubMed

    Guo, Zhiyong; Shao, Changlun; She, Zhigang; Cai, Xiaoling; Liu, Fan; Vrijimoed, L L P; Lin, Yongcheng

    2007-05-01

    The complete (1)H and (13)C NMR assignments are reported for the novel natural product Bacillosporin D together with the known compound Bacillosporin C. These compounds containing seven rings were isolated from the mangrove endophytic fungus SBE-14 from the South China Sea. 1D and 2D NMR experiments, including COSY, HMQC and HMBC were used to the determination of the structures and NMR assignments. It is proposed that 1 was biogenetically produced by transforming 2. Transforming a lactone to an anhydride is unusual in nature.

  7. The economical synthesis of [2'-(13)C, 1,3-(15)N2]uridine; preliminary conformational studies by solid state NMR.

    PubMed

    Patching, Simon G; Middleton, David A; Henderson, Peter J F; Herbert, Richard B

    2003-06-21

    The synthesis of [2'-(13)C, 1,3-(15)N2]uridine 11 was achieved as follows. An epimeric mixture of D-[1-(13)C]ribose 3 and D-[1-(13)C]arabinose 4 was obtained in excellent yield by condensation of K13CN with D-erythrose 2 using a modification of the Kiliani-Fischer synthesis. Efficient separation of the two aldose epimers was pivotally achieved by a novel ion-exchange (Sm3+) chromatography method. D-[2-(13)C]Ribose 5 was obtained from D-[1-(13)C]arabinose 4 using a Ni(II) diamine complex (nickel chloride plus TEMED). Combination of these procedures in a general cycling manner can lead to the very efficient preparation of specifically labelled 13C-monosaccharides of particular chirality. 15N-labelling was introduced in the preparation of [2'-(13)C, 1,3-(15)N2]uridine 11 via [15N2]urea. Cross polarisation magic angle spinning (CP-MAS) solid-state NMR experiments using rotational echo double resonance (REDOR) were carried out on crystals of the labelled uridine to show that the inter-atomic distance between C-2' and N-1 is closely similar to that calculated from X-ray crystallographic data. The REDOR method will be used now to determine the conformation of bound substrates in the bacterial nucleoside transporters NupC and NupG.

  8. Interaction between a recombinant prion protein and organo-mineral complexes as evidenced by CPMAS 13C-NMR

    NASA Astrophysics Data System (ADS)

    Russo, F.; Scotti, R.; Gianfreda, L.; Conte, P.; Rao, M. A.

    2009-04-01

    Prion proteins (PrP) are the main responsible for Transmissible Spongiform Encephalopathies (TSE). The TSE etiological agent is a misfolded form of the normal cellular prion protein. The amyloidal aggregates accumulated in the brain of infected animals and mainly composed of PrPSc exhibit resistance to protease attack and many conventional inactivating procedures. The prion protein diseases cause an environmental issue because the environment and in particular the soil compartment can be contaminated and then become a potential reservoir and diffuser of TSEs infectivity as a consequence of (i) accidental dispersion from storage plants of meat and bone meal, (ii) incorporation of contaminated material in fertilizers, (iii) possible natural contamination of pasture soils by grazing herds, and (v) burial of carcasses. The environmental problem can be even more relevant because very low amounts of PrPSc are able to propagate the disease. Several studies evidenced that infectious prion protein remains active in soils for years. Contaminated soils result, thus, a possible critical route of TSE transmission in wild animals. Soil can also protect prion protein toward degradation processes due to the presence of humic substances and inorganic components such as clays. Mineral and organic colloids and the more common association between clay minerals and humic substances can contribute to the adsorption/entrapment of molecules and macromolecules. The polymerization of organic monomeric humic precursors occurring in soil in the presence of oxidative enzymes or manganese and iron oxides, is considered one of the most important processes contributing to the formation of humic substances. The process is very fast and produces a population of polymeric products of different molecular structures, sizes, shapes and complexity. Other molecules and possibly biomacromolecules such as proteins may be involved. The aim of the present work was to study by CPMAS 13C-NMR the interactions

  9. Microscopic structure of heterogeneous lipid-based formulations revealed by 13C high-resolution solid-state and 1H PFG NMR methods.

    PubMed

    Guillermo, Armel; Gerbaud, Guillaume; Bardet, Michel

    2010-03-01

    Lipid-based formulations such as lip glosses that are very alike on the base of their components may have significant differences in their expected macroscopic properties as cosmetics. To differentiate such formulations, high-resolution (13)C NMR was performed under magic angle spinning to investigate the properties at both molecular and microscopic levels. Temperature studies were carried out and no polymorphism in the solid domains could be evidenced after the thermal treatment performed for obtaining the commercial lip glosses. (13)C NMR spectra also showed that some waxes remain partially solubilized in the oils of formulations. The microscopic structure of the wax-oil liquid domains was worked out on the basis of restricted diffusion properties obtained with proton pulsed-field gradient NMR. Changing a single wax component, in two identical formulations, yields significant morphological differences. In the first one the liquid phase appears as a continuum whereas in the second one, the liquid phase is fractionated into micrometric droplets.

  10. Solid state {sup 1}H and {sup 13}C NMR structural investigation of a poly(ethylene oxide) hydrogel

    SciTech Connect

    Badiger, M.V.; Graham, N.B.; Law, R.V.; Snape, C.E.

    1993-12-31

    A cross-linked poly (ethylene oxide)/polyurethane hydrogel cross-linked with 1,2,6 hexane-triol and designated PEG4050/1HT [measured M{sup n} of 4050 for poly (ethylene oxide) glycol (PEG) and a mole ratio of 1:1 for the PEG to the 1,2,6 hexane-triol] has been characterized by high resolution {sup 1}H and {sup 13}C NMR. {sup 1}H thermal (T{sub 1}) and rotating frame (T{sub 1{rho}}) and {sup 13}CT{sub 1} relaxation times were determined for the powdered dry and swollen hydrogel with the standard variants of the cross-polarization pulse sequence which was used in conjunction with magic-angle spinning (MAS). The rotating frame relaxation measurements confirmed that crystalline and amorphous regions were present in the dry hydrogel but showed unabiguously that the crystalline regions are confined to the poly (ethylene oxide) chains, Upon hydration, there is a decrease in the cross polarization efficiency from the enhanced mobility by the poly (ethylene oxide) chains are affected to a much greater extent that the urethane and hexane segments, the characteristic time constant, T{sub CH} increasing by more than order of magnitude compared to no more than a factor of two for the latter. Clearly, the hydration involves hydrogen bonding between the water and principally the oxygens in the poly (ethylene oxide) chains. The {sup 1}H MAS spectra of the dry and hydrated samples confirmed that considerable averaging of the dipolar interactions occurs on hydration to give a well-resolved spectrum.

  11. Polydisperse methyl β-cyclodextrin–epichlorohydrin polymers: variable contact time 13C CP-MAS solid-state NMR characterization

    PubMed Central

    Mallard, Isabelle; Baudelet, Davy; Castiglione, Franca; Ferro, Monica; Panzeri, Walter; Ragg, Enzio

    2015-01-01

    Summary The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were obtained and characterized by solid-state 13C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: T CH (the CP time constant) and T 1ρ (the proton spin-lattice relaxation time in the rotating frame). The results and the analysis presented in the paper pointed out that T CH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T 1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of T CH and T 1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices. PMID:26877800

  12. Alkaline Hydrolysis/Polymerization of 2,4,6-Trinitrotoluene: Characterization of Products by 13C and 15N NMR

    USGS Publications Warehouse

    Thorn, K.A.; Thorne, P.G.; Cox, L.G.

    2004-01-01

    Alkaline hydrolysis has been investigated as a nonbiological procedure for the destruction of 2,4,6-trinitrotoluene (TNT) in explosives contaminated soils and munitions scrap. Nucleophilic substitutions of the nitro and methyl groups of TNT by hydroxide ion are the initial steps in the alkaline degradation of TNT. Potential applications of the technique include both in situ surface liming and ex situ alkaline treatment of contaminated soils. A number of laboratory studies have reported the formation of an uncharacterized polymeric material upon prolonged treatment of TNT in base. As part of an overall assessment of alkaline hydrolysis as a remediation technique, and to gain a better understanding of the chemical reactions underlying the hydrolysis/polymerization process, the soluble and precipitate fractions of polymeric material produced from the calcium hydroxide hydrolysis of unlabeled and 15N-labeled TNT were analyzed by elemental analysis and 13C and 15N nuclear magnetic resonance spectroscopy. Spectra indicated that reactions leading to polymerization included nucleophilic displacement of nitro groups by hydroxide ion, formation of ketone, carboxyl, alcohol, ether, and other aliphatic carbons, conversion of methyl groups to diphenyl methylene carbons, and recondensation of aromatic amines and reduced forms of nitrite, including ammonia and possibly hydroxylamine, into the polymer. Compared to the distribution of carbons in TNT as 14% sp 3- and 86% sp2-hybridized, the precipitate fraction from hydrolysis of unlabeled TNT contained 33% sp3- and 67% sp 2-hybridized carbons. The concentration of nitrogen in the precipitate was 64% of that in TNT. The 15N NMR spectra showed that, in addition to residual nitro groups, forms of nitrogen present in the filtrate and precipitate fractions include aminohydroquinone, primary amide, indole, imine, and azoxy, among others. Unreacted nitrite was recovered in the filtrate fraction. The toxicities and susceptibilities to

  13. Polydisperse methyl β-cyclodextrin-epichlorohydrin polymers: variable contact time (13)C CP-MAS solid-state NMR characterization.

    PubMed

    Mallard, Isabelle; Baudelet, Davy; Castiglione, Franca; Ferro, Monica; Panzeri, Walter; Ragg, Enzio; Mele, Andrea

    2015-01-01

    The polymerization of partially methylated β-cyclodextrin (CRYSMEB) with epichlorohydrin was carried out in the presence of a known amount of toluene as imprinting agent. Three different preparations (D1, D2 and D3) of imprinted polymers were obtained and characterized by solid-state (13)C NMR spectroscopy under cross-polarization magic angle spinning (CP-MAS) conditions. The polymers were prepared by using the same synthetic conditions but with different molar ratios of imprinting agent/monomer, leading to morphologically equivalent materials but with different absorption properties. The main purpose of the work was to find a suitable spectroscopic descriptor accounting for the different imprinting process in three homogeneous polymeric networks. The polymers were characterized by studying the kinetics of the cross-polarization process. This approach is based on variable contact time CP-MAS spectra, referred to as VCP-MAS. The analysis of the VCP-MAS spectra provided two relaxation parameters: T CH (the CP time constant) and T 1ρ (the proton spin-lattice relaxation time in the rotating frame). The results and the analysis presented in the paper pointed out that T CH is sensitive to the imprinting process, showing variations related to the toluene/cyclodextrin molar ratio used for the preparation of the materials. Conversely, the observed values of T 1ρ did not show dramatic variations with the imprinting protocol, but rather confirmed that the three polymers are morphologically similar. Thus the combined use of T CH and T 1ρ can be helpful for the characterization and fine tuning of imprinted polymeric matrices. PMID:26877800

  14. Computational identification of a phospholipidosis toxicophore using (13)C and (15)N NMR-distance based fingerprints.

    PubMed

    Slavov, Svetoslav H; Wilkes, Jon G; Buzatu, Dan A; Kruhlak, Naomi L; Willard, James M; Hanig, Joseph P; Beger, Richard D

    2014-12-01

    Modified 3D-SDAR fingerprints combining (13)C and (15)N NMR chemical shifts augmented with inter-atomic distances were used to model the potential of chemicals to induce phospholipidosis (PLD). A curated dataset of 328 compounds (some of which were cationic amphiphilic drugs) was used to generate 3D-QSDAR models based on tessellations of the 3D-SDAR space with grids of different density. Composite PLS models averaging the aggregated predictions from 100 fully randomized individual models were generated. On each of the 100 runs, the activities of an external blind test set comprised of 294 proprietary chemicals were predicted and averaged to provide composite estimates of their PLD-inducing potentials (PLD+ if PLD is observed, otherwise PLD-). The best performing 3D-QSDAR model utilized a grid with a density of 8ppm×8ppm in the C-C region, 8ppm×20ppm in the C-N region and 20ppm×20ppm in the N-N region. The classification predictive performance parameters of this model evaluated on the basis of the external test set were as follows: accuracy=0.70, sensitivity=0.73 and specificity=0.66. A projection of the most frequently occurring bins on the standard coordinate space suggested a toxicophore composed of an aromatic ring with a centroid 3.5-7.5Å distant from an amino-group. The presence of a second aromatic ring separated by a 4-5Å spacer from the first ring and at a distance of between 5.5Å and 7Å from the amino-group was also associated with a PLD+ effect. These models provide comparable predictive performance to previously reported models for PLD with the added benefit of being based entirely on non-confidential, publicly available training data and with good predictive performance when tested in a rigorous, external validation exercise.

  15. 1H and 13C NMR studies of glycine in anisotropic media: Double-quantum transitions and the effects of chiral interactions

    NASA Astrophysics Data System (ADS)

    Naumann, Christoph; Kuchel, Philip W.

    2011-07-01

    The 1H NMR spectrum of glycine in stretched gelatin gel and in cromolyn liquid crystal displays a well-resolved doublet due to 1H- 1H dipolar interaction. Multiple spectra were obtained within a wide range of offset frequencies of partially saturating radio-frequency (RF) radiation to generate steady-state irradiation envelopes or z-spectra of glycine. Maximal suppression of the doublet occurred when the irradiation was applied exactly at the centre frequency, between the two glycine peaks. This phenomenon is due to double-quantum transitions and is similar to our previous work on quadrupolar nuclei 2H (HDO) and 23Na +. When the 13C isotopomer glycine-2- 13C was used, the same effect was found in twice, split by 1JCH + 2 DCH. Additional signals in 1H and 13C NMR due to prochiral-chiral interactions were found when glycine-2- 13C was dissolved in chiral anisotropic gelatin and κ-carrageenan gels. The NMR spectra were successfully simulated assuming a 2JHH coupling constant of -16.5 Hz and two distinct dipolar coupling constants for the - 13CH 2- group ( DC,HA, and DC,HB).

  16. Major Groove Width Variations in RNA Structures Determined by NMR and Impact of 13C residual chemical shift anisotropy and 1H-13C residual dipolar coupling on refinement

    PubMed Central

    Tolbert, Blanton S; Miyazaki, Yasuyuki; Barton, Shawn; Kinde, Benyam; Starck, Patrice; Singh, Rashmi; Bax, Ad

    2010-01-01

    Ribonucleic acid structure determination by NMR spectroscopy relies primarily on local structural restraints provided by 1H-1H NOEs and J-couplings. When employed loosely, these restraints are broadly compatible with A- and B-like helical geometries and give rise to calculated structures that are highly sensitive to the force fields employed during refinement. A survey of recently reported NMR structures reveals significant variations in helical parameters, particularly the major groove width. Although helical parameters observed in high-resolution X-ray crystal structures of isolated A-form RNA helices are sensitive to crystal packing effects, variations among the published X-ray structures are significantly smaller than those observed in NMR structures. Here we show that restraints derived from aromatic 1H-13C residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) can overcome NMR restraint and force field deficiencies and afford structures with helical properties similar to those observed in high-resolution X-ray structures. PMID:20549304

  17. Solid-state (13)C NMR and synchrotron SAXS/WAXS studies of uniaxially-oriented polyethylene.

    PubMed

    Afeworki, Mobae; Brant, Pat; Lustiger, Arnold; Norman, Alexander

    2015-11-01

    We report solid-state (13)C NMR and synchrotron wide-and small-angle X-ray scattering experiments (WAXS, SAXS) on metallocene linear low density polyethylene films (e.g., Exceed™ 1018 mLLDPE; nominally 1MI, 0.918 density ethylene-hexene metallocene copolymer) as a function of uniaxial draw ratio, λ. Combined, these experiments provide an unambiguous, quantitative molecular view of the orientation of both the crystalline and amorphous phases in the samples as a function of draw. Together with previously reported differential scanning calorimetry (DSC), gas transport measurements, transmission electron microscopy (TEM), optical birefringence, small angle X-ray scattering (SAXS) as well as other characterization techniques, this study of the state of orientation in both phases provides insight concerning the development of unusually high barrier properties of the most oriented samples (λ=10). In this work, static (non-spinning) solid-state NMR measurements indicate that in the drawn Exceed(TM) films both the crystalline and amorphous regions are highly oriented. In particular, chemical shift data show the amorphous phase is comprised increasingly of so-called "taut tie chains" (or tie chains under any state of tautness) in the mLLDPE with increasing draw ratio - the resonance lines associated with the amorphous phase shift to where the crystalline peaks are observed. In the sample with highest total draw (λ=10), virtually all of the chains in the non-crystalline region have responded and aligned in the machine (draw) direction. Both monoclinic and orthorhombic crystalline peaks are observed in high-resolution, solid-state magic-angle spinning (MAS) NMR measurements of the oriented PE films. The orientation is comparable to that obtained for ultra-high molecular weight HDPE fibers described as "ultra-oriented" in the literature. Furthermore, the presence of a monoclinic peak in cold-drawn samples suggests that there is an appreciable internal stress associated

  18. Tamoxifen-model membrane interactions: an FT-IR study

    NASA Astrophysics Data System (ADS)

    Boyar, Handan; Severcan, Feride

    1997-06-01

    The temperature- and concentration-induced effects of tamoxifen (TAM) on dipalmitoyl phosphatidylcholine (DPPC) model membranes were investigated by the Fourier transform-infrared (FT-IR) spectroscopic technique. An investigation of the C-H stretching region and the CO mode reveals that the inclusion of TAM changes the physical properties of the DPPC multibilayers by (i) shifting the main phase transition to lower temperatures; (ii) broadening the transition profile slightly; (iii) disordering the system in the gel and in the liquid crystalline phases; (iv) increasing the dynamics in the gel phase and decreasing the dynamics of the acyl chains in the liquid crystalline phase; (v) increasing the mobility of the terminal methyl group region of the bilayer in the gel phase and decreasing it in the liquid crystalline phase; (vi) increasing the frequency of the CO stretching mode both in the gel and in the liquid crystalline phases, i.e. non-bonding with carbonyl groups.

  19. In Situ 13C NMR at Elevated-Pressures and -Temperatures Investigating the Conversion of CO2 to Magnesium and Calcium Carbonate Minerals

    NASA Astrophysics Data System (ADS)

    Surface, J. A.; Conradi, M. S.; Skemer, P. A.; Hayes, S. E.

    2013-12-01

    We have constructed specialized NMR hardware to conduct in situ elevated-pressure, elevated-temperature 13C NMR studies of unmixed heterogeneous mixtures of solids, liquids, gases, and supercritical fluids. Specifically, our aim is to monitor CO2 uptake in both ultramafic rocks and in more porous geological materials to understand the mechanisms of chemisorption as a function of temperature, pressure and pH. In this in situ NMR probe, we are able to simulate processes at geologically relevant fluid pressures and temperatures, monitoring the kinetics of CO2 conversion to carbonates. The in situ NMR experiments consist of heterogeneous mixtures of rock, salty brine solution, and moderate pressure CO2 gas at elevated temperatures. The purpose of studying these reactions is to determine efficacy of carbonate formation in various geological reservoirs. Via 13C NMR, we have spectroscopically characterized and quantified the conversion of CO2 to magnesium carbonate and calcium carbonate minerals. When CO2 reacts with the calcium or magnesium in a mineral or rock sample, the 13C chemical shift, linewidth, lineshape, and relaxation times change dramatically. This change can be monitored in situ and provide instantaneous and continuous characterization that maps the chemistry that is taking place. For example, on the pathway to MgCO3 formation, there are a number of phases of Mg(OH)x(H2O)y(CO3)z that are apparent via NMR spectroscopy. We will demonstrate that NMR can be used for quantitative characterization of multiple metastable mineral phases in pure forms and in mixtures. Results are confirmed via powder XRD and Raman spectroscopy of aquo- hydro- carbonato- magnesium species and calcium carbonate species. We also have monitored the 13C spectroscopy to analyze the phase of CO2 (liquid, supercritical, or gas) and its conversion into other forms, such as bicarbonate and carbonate species, providing a "window" into the in situ pH of the reacting system. Reference: 'In Situ

  20. 13C-NMR of ribosyl A-A-A, A-A-G, and A-U-G. Synthesis and assignment.

    PubMed

    Stone, M P; Winkle, S A; McFarland, G D; Yoo, M C; Borer, P N

    1985-11-01

    The three RNA trinucleotides; ApApA, ApApG, and ApUpG, have been synthesized in sufficient quantity to obtain natural abundance 13C(1H)-NMR spectra at strand concentrations between 4 and 100 mM. Comparisons between 70 degrees C spectra of the three trimers and their consistuent dimers ApA, ApG, ApU, and UpG allow secure assignments to be made for most of the resonances. This paper describes the syntheses and 13C assignments of the oligomers.

  1. Micro FT-IR Characterization Of Human Lung Tumor Cells

    NASA Astrophysics Data System (ADS)

    Benedetti, Enzo; Teodori, L.; Vergamini, Piergiorgio; Trinca, M. L.; Mauro, F.; Salvati, F.; Spremolla, Giuliano

    1989-12-01

    FT-IR spectroscopy has opened up a new approach to the analytical study of cell transformation. Investigations carried out in normal and leukemic lymphocytes have evidenced an increase in DNA with respect to proteic components in neoplastic cells.(1) The evaluation of the ratio of the integrated areas(A) of the bands at 1080 cm-1 (mainly DNA) and at 1540 cm-1 (proteic components) has allowed us to establish a parameter which indicates, for values above 1.5, the neoplastic nature of cells. Recently, this approach has been applied to the study of human lung tumor cells. Several monocellular suspension procedures of the tissue fragment (mechanical and/or chemical) were tested to obtain reproducible and reliable spectra able to differentiate clearly between normal and patological cells. Chemical treatment (EDTA, Pepsin, Collagenase, etc.) produced additional bands in the spectra of the cells causing distortion of the profiles of some absorptions, and as a result, mechanical treatment was preferred. The normal and neoplastic cells homogeneously distributed by cytospin preparation on BaF2 windows were examined by means of FT-IR microscopy. An examination of several microareas of each sample yielded reproducible spectra, with values of the A 1080 cm-1 / A 1540 cm-1 parameter within a very narrow range for each sample, even if certain differences still remained among the different cases, in good agreement with the results obtained for leukemic cells.(1) The value of this parameter was found to be lower for cells isolated from the normal area of lung, than in the case of those corresponding to the tumoral area, meaning that an increase occurs in DNA with respect to the proteic components. These insights, which provide a basis to obtain indications at the molecular level, can open up new possibilities in clinical practice, in order to obtain diagnosis confirmation, to detect early stages of disease and to offer additional indications in cases of dubious interpretation.

  2. High-resolution solid-state 13C NMR spectroscopy of the paramagnetic metal-organic frameworks, STAM-1 and HKUST-1.

    PubMed

    Dawson, Daniel M; Jamieson, Lauren E; Mohideen, M Infas H; McKinlay, Alistair C; Smellie, Iain A; Cadou, Romain; Keddie, Neil S; Morris, Russell E; Ashbrook, Sharon E

    2013-01-21

    Solid-state (13)C magic-angle spinning (MAS) NMR spectroscopy is used to investigate the structure of the Cu(II)-based metal-organic frameworks (MOFs), HKUST-1 and STAM-1, and the structural changes occurring within these MOFs upon activation (dehydration). NMR spectroscopy is an attractive technique for the investigation of these materials, owing to its high sensitivity to local structure, without any requirement for longer-range order. However, interactions between nuclei and unpaired electrons in paramagnetic systems (e.g., Cu(II)-based MOFs) pose a considerable challenge, not only for spectral acquisition, but also in the assignment and interpretation of the spectral resonances. Here, we exploit the rapid T(1) relaxation of these materials to obtain (13)C NMR spectra using a spin-echo pulse sequence at natural abundance levels, and employ frequency-stepped acquisition to ensure uniform excitation of resonances over a wide frequency range. We then utilise selective (13)C isotopic labelling of the organic linker molecules to enable an unambiguous assignment of NMR spectra of both MOFs for the first time. We show that the monomethylated linker can be recovered from STAM-1 intact, demonstrating not only the interesting use of this MOF as a protecting group, but also the ability (for both STAM-1 and HKUST-1) to recover isotopically-enriched linkers, thereby reducing significantly the overall cost of the approach.

  3. The 'Nuts and Bolts' of 13C NMR Spectroscopy at Elevated-Pressures and -Temperatures for Monitoring In Situ CO2 Conversion to Metal Carbonates

    NASA Astrophysics Data System (ADS)

    Moore, J. K.; Surface, J. A.; Skemer, P. A.; Conradi, M. S.; Hayes, S. E.

    2013-12-01

    We will present details of newly-constructed specialized NMR designed to conduct in situ elevated-pressure, elevated-temperature 13C NMR studies on unmixed slurries of minerals in the presence of CO2 or other gases. This static probe is capable of achieving 300 bar, 300C conditions, and it is designed to spectroscopically examine 13C signals in mixtures of solids, liquids, gases, and supercritical fluids. Ultimately, our aim is to monitor CO2 uptake in both ultramafic rocks and in more porous geological materials to understand the mechanisms of chemisorption as a function of temperature, pressure and pH. We will give details of the hardware setup, and we will show a variety of static in situ NMR, as well as ex situ 'magic-angle spinning' NMR to show the analyses that are possible of minerals in pure form and in mixtures. In addition, specific NMR pulse sequences, techniques, and modeling will be described in detail. In this in situ NMR probe, we are able to simulate processes at geologically relevant fluid pressures and temperatures, monitoring the kinetics of CO2 conversion to carbonates. The in situ NMR experiments consist of heterogeneous mixtures of rock, salty brine solution, and moderate pressure CO2 gas at elevated temperatures. The purpose of studying these reactions is to determine conditions that affect the efficacy of carbonate formation in various targeted geological reservoirs (i.e., peroditite, or others). Via 13C NMR, we have spectroscopically characterized and quantified the conversion of CO2 to magnesium carbonate and calcium carbonate minerals, including metastable intermediates (such as hydromagnesite, or dypingite in the case of magnesium carbonate species, or vaterite in the case of calcium carbonate species). Such species are distinguishable from a combination of the 13C isotropic chemical shift, the static 13C lineshape, and changes in spin-lattice (T1) relaxation times. We will demonstrate that NMR can be used for quantitative

  4. Spectroscopic [FT-IR and FT-Raman] and molecular modeling (MM) study of benzene sulfonamide molecule using quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Vinod, K. S.; Periandy, S.; Govindarajan, M.

    2016-07-01

    The spectroscopic and molecular modeling (MM) study includes, FT-IR, FT-Raman and 13C NMR and 1H NMR spectra of the Benzene sulfonamide were recorded for the analysis. The observed experimental and theoretical frequencies (IR and Raman) were assigned according to their distinctive region. The present study of this title molecule have been carried out by hybrid computational calculations of HF and DFT (B3LYP) methods with 6-311+G(d,p) and 6-311++G(d,p) basis sets and the corresponding results are tabulated. The structural modifications of the compound due to the substitutions of NH2 and SO2 were investigated. The minimum energy conformers of the compound were studied using conformational analysis. The alternations of the vibrational pattern of the base structure related to the substitutions were analyzed. The thermodynamic parameters (such as zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment) of Benzene sulfonamide have been calculated. The donor acceptor interactions of the compound and the corresponding UV transitions are found out using NBO analysis. The NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts related to TMS were compared. A quantum computational study on the electronic and optical properties absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by HF and DFT methods. The energy gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand group. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase and

  5. A [sup 13]C NMR study of ethylene adsorbed on reduced and oxygen-covered Ag surfaces

    SciTech Connect

    Plischke, J.K.; Benesi, A.J.; Vannice, M.A. )

    1992-11-01

    [sup 13]C-enriched ethylene was adsorbed on both clean and oxygen-covered Ag particles dispersed on [eta]-Al[sub 2]O[sub 3]. Irreversibly adsorbed C[sub 2]H[sub 4] on O-covered Ag exhibited an upfield shift of [minus]20 ppm relative to gas-phase C[sub 2]H[sub 4], whereas a narrower line and smaller shift of [minus]5 ppm occurred for C[sub 2]H[sub 4] reversibly adsorbed on reduced Ag. In addition to the resonance at 103 ppm for irreversibly adsorbed C[sub 2]H[sub 4], CP/MAS NMR spectra also gave resonances at 179, 170, 164, 159, and 19 ppm for the O-covered Ag sample. The CP/MAS spectrum for Ag acetate powder clearly identified the 179- and 19-ppm peaks as those associated with the carboxyl and methyl carbons of the acetate anion, and the peaks at 159, 164, and 170 ppm were assigned to oxalate, formate, and carbonate (or possibly acetic anhydride) species, respectively, based on previous studies. When heated to 473 K the adsorbed C[sub 2]H[sub 4] disappeared and only acetate and oxalate groups were observed, and continued heating to 573 K removed almost all resonances. No C[sub 2]H[sub 4]O was unambiguously detected, thus with this unpromoted Ag catalyst utilizing a high-surface-area alumina the observable surface species appeared to be those associated with complete combustion, with acetate and oxalate predominating during reaction. These results directly confirm the presence of an Ag acetate species which has been proposed previously to be an intermediate in complete combustion, and the presence of the other three species support earlier tentative assignments based on IR and TPR spectroscopy. Chemical shifts at 61, 28, and 13 ppm were indicative of alkoxy species formed on Bronsted-acid sites on the Al[sub 2]O[sub 3] surface. 58 refs., 8 figs., 4 tabs.

  6. Characterization and differentiation of high energy cyclic organic peroxides by GC/FT-IR, GC-MS, FT-IR, and Raman microscopy

    NASA Astrophysics Data System (ADS)

    Pena, Alvaro J.; Pacheco-Londono, Leonardo; Figueroa, Javier; Rivera-Montalvo, Luis A.; Roman-Velazquez, Felix R.; Hernandez-Rivera, Samuel P.

    2005-05-01

    The characterization of Tetracetone Tetraperoxide (TRATRP), Triacetone Triperoxide (TATP), Diacetone Diperoxide (DADP), Tricyclohexylidene Triperoxide and Dibenzo Diperoxide using GC-MS, GC-FTIR, FTIR, FT-NMR and Raman Spectroscopy is reported. These compounds were synthesized, purified and characterized in the laboratory in order to develop methodologies for their trace detection. During this study, TATP has been synthesized by different methods obtaining high purity and good yields, even using common household products. DADP synthetic routes reported in the literature were verified. The methods described, including those that produce mixtures with TATP and other peroxides forms were also tested. This study will also focused in the preparation of other cyclic peroxides, including Hexamethelene Triperoxide Diamine (HMTD) and different forms of cyclic peroxides from ketones. This issue of thermodynamic versus kinetic control of secondary products of all syntheses and the effect of temperature in the distribution sub products of the syntheses was also addressed. A vibrational differentiation study of was carried out. Differences were found computationally in the υ(O-O), υ(C-O), δ(CH3-C) and δ(C-O) for Raman and IR bands and retention time and fragment patron for GC-MS and GC-FT-IR.

  7. Geometries and tautomerism of OHN hydrogen bonds in aprotic solution probed by H/D isotope effects on (13)C NMR chemical shifts.

    PubMed

    Tolstoy, Peter M; Guo, Jing; Koeppe, Benjamin; Golubev, Nikolai S; Denisov, Gleb S; Smirnov, Sergei N; Limbach, Hans-Heinrich

    2010-10-14

    The (1)H and (13)C NMR spectra of 17 OHN hydrogen-bonded complexes formed by CH(3)(13)COOH(D) with 14 substituted pyridines, 2 amines, and N-methylimidazole have been measured in the temperature region between 110 and 150 K using CDF(3)/CDF(2)Cl mixture as solvent. The slow proton and hydrogen bond exchange regime was reached, and the H/D isotope effects on the (13)C chemical shifts of the carboxyl group were measured. In combination with the analysis of the corresponding (1)H chemical shifts, it was possible to distinguish between OHN hydrogen bonds exhibiting a single proton position and those exhibiting a fast proton tautomerism between molecular and zwitterionic forms. Using H-bond correlations, we relate the H/D isotope effects on the (13)C chemical shifts of the carboxyl group with the OHN hydrogen bond geometries.

  8. Systematic Comparison of Sets of 13C NMR Spectra That Are Potentially Identical. Confirmation of the Configuration of a Cuticular Hydrocarbon from the Cane Beetle Antitrogus parvulus

    PubMed Central

    2015-01-01

    A systematic process is introduced to compare 13C NMR spectra of two (or more) candidate samples of known structure to a natural product sample of unknown structure. The process is designed for the case where the spectra involved can reasonably be expected to be very similar, perhaps even identical. It is first validated by using published 13C NMR data sets for the natural product 4,6,8,10,16,18-hexamethyldocosane. Then the stereoselective total syntheses of two candidate isomers of the related 4,6,8,10,16-pentamethyldocosane natural product are described, and the process is applied to confidently assign the configuration of the natural product as (4S,6R,8R,10S,16S). This is accomplished even though the chemical shift differences between this isomer and its (16R)-epimer are only ±5–10 ppb (±0.005–0.01 ppm). PMID:25019530

  9. Combined analysis by GC (RI), GC-MS and 13C NMR of the supercritical fluid extract of Abies alba twigs.

    PubMed

    Duquesnoy, Emilie; Marongiu, Bruno; Castola, Vincent; Piras, Alessandra; Porcedda, Silvia; Casanova, Joseph

    2010-12-01

    Two samples (leaves and twigs) of Abies alba Miller from Corsica were extracted using supercritical CO2 and their chemical compositions were compared with those of the essential oils obtained from the same batch of plant material. In total 45 components were identified using combined analysis by GC (RI), GC-MS and 13C NMR. It was observed that the contents of monoterpenes (mainly represented by limonene, alpha-pinene and camphene) were significantly lower in the supercritical fluid extract (SFE) than in the essential oil (EO). Conversely, the proportions of sesquiterpenes were much higher in CO2 extracts than in essential oils (around 30% vs 4%). Cis-abienol, a diterpene alcohol, was identified only in SFE, and the proportions of this constituent (7.5% and 17.3%) were determined using quantitative 13C NMR since it was under estimated using the standard conditions of GC. PMID:21299139

  10. Identification of archaeological triterpenic resins by the non-separative techniques FTIR and 13C NMR: the case of Pistacia resin (mastic) in comparison with frankincense.

    PubMed

    Bruni, Silvia; Guglielmi, Vittoria

    2014-01-01

    The use of spectroscopic techniques such as Fourier-transform infrared (FTIR) spectroscopy and carbon 13 nuclear magnetic resonance ((13)C NMR) using the J-mod experiment is proposed as an effective alternative to gas chromatography-mass spectrometry (GC-MS) for the analysis and identification of natural resin samples found in archaeological environments. The spectral features of the most common diterpenic and triterpenic resins and also two gum-resins are reported and discussed for both techniques. The analytical procedure based on the combined use of FTIR and (13)C NMR is then applied to two archaeological samples from the Milano of the Roman age allowing their identification as Pistacia resin, or mastic, as confirmed by the traditional GC-MS method, and also elucidating some effects of aging on such material.

  11. Combined analysis by GC (RI), GC-MS and 13C NMR of the supercritical fluid extract of Abies alba twigs.

    PubMed

    Duquesnoy, Emilie; Marongiu, Bruno; Castola, Vincent; Piras, Alessandra; Porcedda, Silvia; Casanova, Joseph

    2010-12-01

    Two samples (leaves and twigs) of Abies alba Miller from Corsica were extracted using supercritical CO2 and their chemical compositions were compared with those of the essential oils obtained from the same batch of plant material. In total 45 components were identified using combined analysis by GC (RI), GC-MS and 13C NMR. It was observed that the contents of monoterpenes (mainly represented by limonene, alpha-pinene and camphene) were significantly lower in the supercritical fluid extract (SFE) than in the essential oil (EO). Conversely, the proportions of sesquiterpenes were much higher in CO2 extracts than in essential oils (around 30% vs 4%). Cis-abienol, a diterpene alcohol, was identified only in SFE, and the proportions of this constituent (7.5% and 17.3%) were determined using quantitative 13C NMR since it was under estimated using the standard conditions of GC.

  12. Chemical composition of the essential oil from Corsican Mentha aquatica--combined analysis by GC(RI), GC-MS and 13C NMR spectroscopy.

    PubMed

    Sutour, Sylvain; Tomi, Félix; Bradesi, Pascale; Casanova, Joseph

    2011-10-01

    The essential oil (EO) of M. aquatica L. growing wild in Corsica was isolated by dry vapor distillation and submitted to combined analysis by column chromatography over silica gel, GC(RI), GC-MS and 13C NMR spectroscopy. The composition was dominated byoxygenated monoterpenes and characterized by the occurrence of menthofuran (50.7%) as the major component. In parallel, seven laboratory-distilled oil samples isolated from individual plants collected in Corsica were analyzed by GC(RI) and 13C NMR spectroscopy. Onlyquantitative differences were observed between the samples. Beside the usual terpenes, various p-menthane lactones (mintlactone, isomintlactone, hydroxymintlactone, menthofurolactone and epimenthofurolactone) have been identified in all the oil samples.

  13. Mechanism of formation of humus coatings on mineral surfaces 3. Composition of adsorbed organic acids from compost leachate on alumina by solid-state 13C NMR

    USGS Publications Warehouse

    Wershaw, R. L.; Llaguno, E.C.; Leenheer, J.A.

    1996-01-01

    The adsorption of compost leachate DOC on alumina is used as a model for elucidation of the mechanism of formation of natural organic coatings on hydrous metal oxide surfaces in soils and sediments. Compost leachate DOC is composed mainly of organic acid molecules. The solid-state 13C NMR spectra of these organic acids indicate that they are very similar in composition to aquatic humic substances. Changes in the solid-state 13C NMR spectra of compost leachate DOC fractions adsorbed on alumina indicate that the DOC molecules are most likely adsorbed on metal oxide surfaces through a combination of polar and hydrophobic interaction mechanisms. This combination of polar and hydrophobic mechanism leads to the formation of bilayer coatings of the leachate molecules on the oxide surfaces.

  14. Direct identification and quantitative determination of costunolide and dehydrocostuslactone in the fixed oil of Laurus novocanariensis by 13C-NMR spectroscopy.

    PubMed

    Ferrari, Bernard; Castilho, Paula; Tomi, Félix; Rodrigues, Ana Isabel; do Ceu Costa, Maria; Casanova, Joseph

    2005-01-01

    The fixed oil of Laurus novocanariensis (previously L. azorica) contains mostly glycerides together with minor non-saponifiable compounds. The direct identification and quantitative determination of costunolide and dehydrocostuslactone, two sesquiterpene lactones components of the oil that exhibit biological activities, is described. The analysis was carried out using 13C-NMR spectroscopy (signal acquisition with inverse gated decoupling of protons; diglyme as internal standard) without separation, derivatisation or any sample preparation.

  15. Identification and quantitative determination of eudesmane-type acids from the essential oil of Dittrichia viscosa sp. viscosa using 13C-NMR spectroscopy.

    PubMed

    Blanc, Marie-Cécile; Bradesi, Pascale; Casanova, Joseph

    2005-01-01

    A procedure that allows the identification and quantitative determination of eudesmane-type acids in the acidic part of the essential oil of Dittrichia viscosa sp. viscosa is described. The method involves the computer-aided analysis of the 13C-NMR spectrum of the mixture without the requirement of previous separation or derivatisation. The quantitative procedure was verified with costic acid standard and applied to three other acids which possess the same eudesmane framework.

  16. Variable temperature 1H and 13C NMR study of restricted rotation in N,N-bis(2-hydroxyethyl)acetamide

    NASA Astrophysics Data System (ADS)

    Aitken, R. Alan; Smith, Melanja H.; Wilson, Heather S.

    2016-06-01

    N,N-bis(2-hydroxyethyl)acetamide shows restricted rotation about the amide bond in both 1H and 13C NMR spectra rendering the two hydroxyethyl groups non-equivalent. A variable temperature study in CD3SOCD3 allowed estimation of the free energy barrier to rotation as 75.6 ± 0.2 kJ mol-1. Previously published data in CDCl3 appears to be erroneous.

  17. 1H and 13C NMR assignments for 6-demethylvermistatin and two penicillide derivatives from the mangrove fungus Guignardia sp. (No. 4382) from the South China Sea.

    PubMed

    Xia, Xue-Kui; Liu, Fan; She, Zhi-Gang; Yang, Li-Guo; Li, Meng-Feng; Vrijmoed, L L P; Lin, Yong-Cheng

    2008-07-01

    One new compound 6-demethylvermistatin (1), together with two known compounds, the penicillide derivatives (2) and (3) were isolated from the mangrove fungus Guignardia sp. No. 4382 obtained from the South China Sea. Their structures were assigned using high-resolution electron ionization mass spectrometry(HREIMS), (1)H and (13)C NMR spectra, DEPT, and by 2D COSY, HMQC, and HMBC experiments. The absolute configuration of 1 was established by comparison of its CD with that of vermistatin.

  18. Hydrogen bonding induced distortion of CO3 units and kinetic stabilization of amorphous calcium carbonate: results from 2D (13)C NMR spectroscopy.

    PubMed

    Sen, Sabyasachi; Kaseman, Derrick C; Colas, Bruno; Jacob, Dorrit E; Clark, Simon M

    2016-07-27

    Systematic correlation in alkaline-earth carbonate compounds between the deviation of the CO3 units from the perfect D3h symmetry and their (13)C nuclear magnetic resonance (NMR) chemical shift anisotropy (CSA) parameters is established. The (13)C NMR CSA parameters of amorphous calcium carbonate (ACC) are measured using two-dimensional (13)C phase adjusted spinning sidebands (PASS) NMR spectroscopy and are analyzed on the basis of this correlation. The results indicate a distortion of the CO3 units in ACC in the form of an in-plane displacement of the C atom away from the centroid of the O3 triangle, resulting from hydrogen bonding with the surrounding H2O molecules, without significant out-of-plane displacement. Similar distortion for all C atoms in the structure of ACC suggests a uniform spatial disposition of H2O molecules around the CO3 units forming a hydrogen-bonded amorphous network. This amorphous network is stabilized against crystallization by steric frustration, while additives such as Mg presumably provide further stabilization by increasing the energy of dehydration. PMID:27276013

  19. Effects of stereoelectronic interactions on the relativistic spin-orbit and paramagnetic components of the (13)C NMR shielding tensors of dihaloethenes.

    PubMed

    Viesser, Renan V; Ducati, Lucas C; Autschbach, Jochen; Tormena, Cláudio F

    2015-07-15

    In this study, stereoelectronic interactions were considered to explain the experimental difference in the magnitude of the known heavy-atom effect on the (13)C NMR chemical shifts in cis- and trans-1,2-dihaloethene isomers (halo = F, Cl, Br or I). The experimental values were compared to the calculated values with various DFT functionals using both the nonrelativistic approach (NR) and the relativistic approximations SR-ZORA (SR) and SO-ZORA (SO). NBO and NLMO contributions to the (13)C NMR shielding tensors were determined to assess which stereoelectronic interactions have a more important effect on the shielding tensor in each principal axis system (PAS) coordinate. These analyses associated with the orbital rotation model and the HOMO-LUMO energy gap enable rationalization of trends between cis and trans isomers from fluorine to iodine derivatives. Both paramagnetic and SO shielding terms were responsible for the observed trends. It was possible to conclude that the steric interactions between the two iodine atoms and the hyperconjugative interactions involving the halogen lone pairs (LP(X)) and πC[double bond, length as m-dash]C*, σC[double bond, length as m-dash]C* and σC-X* antibonding orbitals are responsible for the lower (13)C NMR shielding for the cis isomers of the bromine and the iodine compounds than that of the trans isomers.

  20. In vivo, large-scale preparation of uniformly (15)N- and site-specifically (13)C-labeled homogeneous, recombinant RNA for NMR studies.

    PubMed

    Le, My T; Brown, Rachel E; Simon, Anne E; Dayie, T Kwaku

    2015-01-01

    Knowledge of how ribonucleic acid (RNA) structures fold to form intricate, three-dimensional structures has provided fundamental insights into understanding the biological functions of RNA. Nuclear magnetic resonance (NMR) spectroscopy is a particularly useful high-resolution technique to investigate the dynamic structure of RNA. Effective study of RNA by NMR requires enrichment with isotopes of (13)C or (15)N or both. Here, we present a method to produce milligram quantities of uniformly (15)N- and site-specifically (13)C-labeled RNAs using wild-type K12 and mutant tktA Escherichia coli in combination with a tRNA-scaffold approach. The method includes a double selection protocol to obtain an E. coli clone with consistently high expression of the recombinant tRNA-scaffold. We also present protocols for the purification of the tRNA-scaffold from a total cellular RNA extract and the excision of the RNA of interest from the tRNA-scaffold using DNAzymes. Finally, we showcase NMR applications to demonstrate the benefit of using in vivo site-specifically (13)C-labeled RNA. PMID:26577743

  1. Rapid adaptation of rat brain and liver metabolism to a ketogenic diet: an integrated study using 1H- and 13C-NMR spectroscopy

    PubMed Central

    Roy, Maggie; Beauvieux, Marie-Christine; Naulin, Jérôme; El Hamrani, Dounia; Gallis, Jean-Louis; Cunnane, Stephen C; Bouzier-Sore, Anne-Karine

    2015-01-01

    The ketogenic diet (KD) is an effective alternative treatment for refractory epilepsy in children, but the mechanisms by which it reduces seizures are poorly understood. To investigate how the KD modifies brain metabolism, we infused control (CT) and 7-day KD rats with either [1-13C]glucose (Glc) or [2,4-13C2]β-hydroxybutyrate (β-HB). Specific enrichments of amino acids (AAs) measured by 1H- and 13C-NMR in total brain perchloric acid extracts were similar between CT and KD rats after [1-13C]Glc infusion whereas they were higher in KD rats after [2,4-13C2]β-HB infusion. This suggests better metabolic efficiency of ketone body utilization on the KD. The relative rapid metabolic adaptation to the KD included (1) 11%-higher brain γ-amino butyric acid (GABA)/glutamate (Glu) ratio versus CT, (2) liver accumulation of the ketogenic branched-chain AAs (BCAAs) leucine (Leu) and isoleucine (ILeu), which were never detected in CT, and (3) higher brain Leu and ILeu contents. Since Glu and GABA are excitatory and inhibitory neurotransmitters, respectively, higher brain GABA/Glu ratio could contribute to the mechanism by which the KD reduces seizures in epilepsy. Increased BCAA on the KD may also contribute to better seizure control. PMID:25785828

  2. Analysis of dynamics and mechanism of ligand binding to Artocarpus integrifolia agglutinin. A 13C and 19F NMR study.

    PubMed

    Krishna Sastry, M V; Swamy, M J; Surolia, A

    1988-10-15

    Binding of 13C-labeled N-acetylgalactosamine (13C-GalNAc) and N-trifluoroacetylgalactosamine (19F-GalNAc) to Artocarpus integrifolia agglutinin has been studied using 13C and 19F nuclear magnetic resonance spectroscopy, respectively. Binding of these saccharides resulted in broadening of the resonances, and no change in chemical shift was observed, suggesting that the alpha- and beta-anomers of 13C-GalNAc and 19F-GalNAc experience a magnetically equivalent environment in the lectin combining site. The alpha- and beta-anomers of 13C-GalNAc and 19F-GalNAc were found to be in slow exchange between free and protein bound states. Binding of 13C-GalNAc was studied as a function of temperature. From the temperature dependence of the line broadening, the thermodynamic and kinetic parameters were evaluated. The association rate constants obtained for the alpha-anomers of 13C-GalNAc and 19F-GalNAc (k+1 = 1.01 x 10(5) M-1.s-1 and 0.698 x 10(5) M-1.s-1, respectively) are in close agreement with those obtained for the corresponding beta-anomers (k+1 = 0.95 x 10(5) M-1.s-1 and 0.65 x 10(5) M-1.s-1, respectively), suggesting that the two anomers bind to the lectin by a similar mechanism. In addition these values are several orders of magnitude slower than those obtained for diffusion controlled processes. The dissociation rate constants obtained are 49.9, 56.9, 42, and 43 s-1, respectively, for the alpha- and beta-anomers of 13C-GalNAc and 19F-GalNAc. A two-step mechanism has been proposed for the interaction of 13C-GalNAc and 19F-GalNAc with A. integrifolia lectin in view of the slow association rates and high activation entropies. The thermodynamic parameters obtained for the association and dissociation reactions suggest that the binding process is entropically favored and that there is a small enthalpic contribution.

  3. 13C CP/MAS NMR Studies of Hemoprotein Models with and without an Axial Hindered Base: (13)C Shielding Tensors and Comparison with Hemoproteins and X-ray Structural Data.

    PubMed

    Gerothanassis, I. P.; Momenteau, M.; Barrie, P. J.; Kalodimos, C. G.; Hawkes, G. E.

    1996-04-24

    13C cross-polarization magic-angle-spinning (CP/MAS) NMR spectra of several carbonmonoxide (93-99% (13)C enriched) hemoprotein models with 1,2-dimethylimidazole (1,2-diMeIm) and 1-methylimidazole (1-MeIm) as axial ligands are reported. This enables the (13)CO spinning sideband manifold to be measured and hence the principal components of the (13)CO chemical shift tensor to be obtained. Negative polar interactions in the binding pocket of the cap porphyrin model and inhibition of Fe-->CO back-donation result in a reduction in shielding anisotropy; on the contrary, positive distal polar interactions result in an increase in the shielding anisotropy and asymmetry parameter in some models. It appears that the axial hindered base 1,2-dimethylimidazole has little direct effect on the local geometry at the CO site, despite higher rates of CO desorption being observed for such complexes. This suggests that the mechanism by which steric interactions are released for the 1,2-diMeIm complexes compared to 1-MeIm complexes does not involve a significant increase in bending of the Fe-C-O unit. The asymmetry of the shielding tensor of all the heme model compounds studied is smaller than that found for horse myoglobin and rabbit hemoglobin.

  4. FT-IR SOLUTION SPECTRA OF PROPYL SULFIDE, PROPYL SULFOXIDE, AND PROPYL SULFONE

    EPA Science Inventory

    FT-IR spectra were obtained of 0.5% volumetric solutions of propyl sulfide, propyl sulfoxide, and propyl sulfone in hexane, CCl4, CS2, and CHCl3 to assist in the assignment of FT-IR-PAS spectra of propyl sulfoxide sorbed within the structure of several peats and onto cellulose. T...

  5. Chemical and nanometer-scale structure of kerogen and its change during thermal maturation investigated by advanced solid-state 13C NMR spectroscopy

    USGS Publications Warehouse

    Mao, J.; Fang, X.; Lan, Y.; Schimmelmann, A.; Mastalerz, Maria; Xu, L.; Schmidt-Rohr, K.

    2010-01-01

    We have used advanced and quantitative solid-state nuclear magnetic resonance (NMR) techniques to investigate structural changes in a series of type II kerogen samples from the New Albany Shale across a range of maturity (vitrinite reflectance R0 from 0.29% to 1.27%). Specific functional groups such as CH3, CH2, alkyl CH, aromatic CH, aromatic C-O, and other nonprotonated aromatics, as well as "oil prone" and "gas prone" carbons, have been quantified by 13C NMR; atomic H/C and O/C ratios calculated from the NMR data agree with elemental analysis. Relationships between NMR structural parameters and vitrinite reflectance, a proxy for thermal maturity, were evaluated. The aromatic cluster size is probed in terms of the fraction of aromatic carbons that are protonated (???30%) and the average distance of aromatic C from the nearest protons in long-range H-C dephasing, both of which do not increase much with maturation, in spite of a great increase in aromaticity. The aromatic clusters in the most mature sample consist of ???30 carbons, and of ???20 carbons in the least mature samples. Proof of many links between alkyl chains and aromatic rings is provided by short-range and long-range 1H-13C correlation NMR. The alkyl segments provide most H in the samples; even at a carbon aromaticity of 83%, the fraction of aromatic H is only 38%. While aromaticity increases with thermal maturity, most other NMR structural parameters, including the aromatic C-O fractions, decrease. Aromaticity is confirmed as an excellent NMR structural parameter for assessing thermal maturity. In this series of samples, thermal maturation mostly increases aromaticity by reducing the length of the alkyl chains attached to the aromatic cores, not by pronounced growth of the size of the fused aromatic ring clusters. ?? 2010 Elsevier Ltd. All rights reserved.

  6. 3-Iodobenzaldehyde: XRD, FT-IR, Raman and DFT studies.

    PubMed

    Kumar, Chandraju Sadolalu Chidan; Parlak, Cemal; Tursun, Mahir; Fun, Hoong-Kun; Rhyman, Lydia; Ramasami, Ponnadurai; Alswaidan, Ibrahim A; Keşan, Gürkan; Chandraju, Siddegowda; Quah, Ching Kheng

    2015-06-15

    The structure of 3-iodobenzaldehyde (3IB) was characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The conformational isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 3IB were examined using density functional theory (DFT) method, with the Becke-3-Lee-Yang-Parr (B3LYP) functional and the 6-311+G(3df,p) basis set for all atoms except for iodine. The LANL2DZ effective core basis set was used for iodine. Potential energy distribution (PED) analysis of normal modes was performed to identify characteristic frequencies. 3IB crystallizes in monoclinic space group P21/c with the O-trans form. There is a good agreement between the theoretically predicted structural parameters, and vibrational frequencies and those obtained experimentally. In order to understand halogen effect, 3-halogenobenzaldehyde [XC6H4CHO; X=F, Cl and Br] was also studied theoretically. The free energy difference between the isomers is small but the rotational barrier is about 8kcal/mol. An atypical behavior of fluorine affecting conformational preference is observed.

  7. 3-Iodobenzaldehyde: XRD, FT-IR, Raman and DFT studies.

    PubMed

    Kumar, Chandraju Sadolalu Chidan; Parlak, Cemal; Tursun, Mahir; Fun, Hoong-Kun; Rhyman, Lydia; Ramasami, Ponnadurai; Alswaidan, Ibrahim A; Keşan, Gürkan; Chandraju, Siddegowda; Quah, Ching Kheng

    2015-06-15

    The structure of 3-iodobenzaldehyde (3IB) was characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The conformational isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 3IB were examined using density functional theory (DFT) method, with the Becke-3-Lee-Yang-Parr (B3LYP) functional and the 6-311+G(3df,p) basis set for all atoms except for iodine. The LANL2DZ effective core basis set was used for iodine. Potential energy distribution (PED) analysis of normal modes was performed to identify characteristic frequencies. 3IB crystallizes in monoclinic space group P21/c with the O-trans form. There is a good agreement between the theoretically predicted structural parameters, and vibrational frequencies and those obtained experimentally. In order to understand halogen effect, 3-halogenobenzaldehyde [XC6H4CHO; X=F, Cl and Br] was also studied theoretically. The free energy difference between the isomers is small but the rotational barrier is about 8kcal/mol. An atypical behavior of fluorine affecting conformational preference is observed. PMID:25767992

  8. 3-Iodobenzaldehyde: XRD, FT-IR, Raman and DFT studies

    NASA Astrophysics Data System (ADS)

    Kumar, Chandraju Sadolalu Chidan; Parlak, Cemal; Tursun, Mahir; Fun, Hoong-Kun; Rhyman, Lydia; Ramasami, Ponnadurai; Alswaidan, Ibrahim A.; Keşan, Gürkan; Chandraju, Siddegowda; Quah, Ching Kheng

    2015-06-01

    The structure of 3-iodobenzaldehyde (3IB) was characterized by FT-IR, Raman and single-crystal X-ray diffraction techniques. The conformational isomers, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 3IB were examined using density functional theory (DFT) method, with the Becke-3-Lee-Yang-Parr (B3LYP) functional and the 6-311+G(3df,p) basis set for all atoms except for iodine. The LANL2DZ effective core basis set was used for iodine. Potential energy distribution (PED) analysis of normal modes was performed to identify characteristic frequencies. 3IB crystallizes in monoclinic space group P21/c with the O-trans form. There is a good agreement between the theoretically predicted structural parameters, and vibrational frequencies and those obtained experimentally. In order to understand halogen effect, 3-halogenobenzaldehyde [XC6H4CHO; X = F, Cl and Br] was also studied theoretically. The free energy difference between the isomers is small but the rotational barrier is about 8 kcal/mol. An atypical behavior of fluorine affecting conformational preference is observed.

  9. Surface characterization of Kevlar fibers by FT-IR spectroscopy

    SciTech Connect

    Chatzi, E.G.

    1987-01-01

    The Kevlar-49 aramid fiber offers considerable potential for utilization in high-performance composite materials. However, it has poor adhesion to the polymer matrix resin. In order to improve the adhesion the surface of the fiber was characterized by using two nondestructive Fourier transform infrared (FT-IR) techniques. It was shown that the polymer chains in the skin are oriented parallel to the surface, while in the core they are almost radially oriented. This orientation as well as the fact that the functional groups are intermolecularly hydrogen-bonded might limit their availability for reacting with the polymer matrix. The author also characterized the water absorbed in both the skin and the core of the fiber and found the existence of three types of water: (a) weakly hydrogen-bonded between one NH and one carbonyl group, (b) between two carbonyl groups and (c) liquid-like water clustered in microvoids and other sites inside the fibers. It was also found that 30% of the NH groups of the Kevlar-49 fiber are accessible for deuterium exchange. These groups on one hand are available for reactions that would improve the adhesion, but on the other hand can hydrogen-bond with water, which would be detrimental for the mechanical properties of the composite.

  10. Detection of modifications in the glucose metabolism induced by genetic mutations in Saccharomyces cerevisiae by 13C- and H-NMR spectroscopy.

    PubMed

    Herve, M; Buffin-Meyer, B; Bouet, F; Son, T D

    2000-06-01

    NMR spectroscopy may offer a suitable technique to characterize the glucose metabolism in response to genetic mutations in cells. The effects of various genetic modifications in Saccharomyces cerevisiae yeast were investigated using 13C- and 1H-NMR spectroscopy associated with biochemical techniques. Cells were incubated with [1-13C]glucose in order to study glucose consumption and the formation of various end-products (ethanol, trehalose, glycerol, glutamate and amino acids) as a function of time. Two types of genetic modifications were studied in S. cerevisiae. A genetic modification deleted the N-terminal part of the TFC7 protein which is the smallest subunit (tau55) of the TFIIIC transcription factor. One secondary effect of this mutation was a large deletion of mitochondrial DNA giving the rho-phenotype. The other genetic modification corresponded to the disruption of the HUF gene; the mutated cells were rho+ like the reference strain. Both mutations increase the glycolysis rate and glycerol synthesis and decrease trehalose production. The most modified cells, which contain both TFC7 deletion and HUF gene disruption, utilize glucose in the most extreme manner as in these cells the largest production of the two glycolytic products (ethanol and glycerol) and the smallest trehalose formation occur. The HUF gene disruption serves as a positive modulator of glycolysis and respiration. However, the TFC7 deletion, associated with the phenotype rho-, induces the most damage in the cellular function, dramatically altering the behaviour of the Krebs cycle. The cycle becomes blocked at the level of 2-oxoglutarate, detected by a characteristic pattern of the 13C-NMR glutamate spectra. These NMR spectra corroborate the phenotypic data, the rho-phenotype corresponding to deletions of mitochondria DNA which block all mitochondria protein synthesis and render the cells unable to derive energy from respiration. Moreover, as a consequence of the Krebs cycle blocking, alanine

  11. Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC

    PubMed Central

    2016-01-01

    Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil.

  12. Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC

    PubMed Central

    2016-01-01

    Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil. PMID:27668136

  13. The conformational stability, solvation and the assignments of the experimental infrared, Raman, 1H and 13C NMR spectra of the local anesthetic drug lidocaine

    NASA Astrophysics Data System (ADS)

    Badawi, Hassan M.; Förner, Wolfgang; Ali, Shaikh A.

    2015-05-01

    The structure, vibrational and 1H and 13C NMR spectra of the local anesthetic drug lidocaine were investigated by the B3LYP/6-311G∗∗ calculations. The molecule was predicted to have the non-planar cis (NCCN ∼ 0°) structures being about 2-6 kcal/mol lower in energy than the corresponding trans (NCCN ∼ 180°) forms. The calculated NCCN (9.6°) and CNCC (-132.2°) torsional angles were in a good qualitative agreement with the reported X-ray angles (3.1 and 13.0°, -102.67 and -77.9°, respectively, for H-bonded dimers). The Gibbs energy of solution of lidocaine in formamide, water, dimethylsulfoxide, acetonitrile, methanol, ethanol and chloroform solutions was estimated at the B3LYP level. The predicted affinity of lidocaine toward the alcohols, acetonitrile and chloroform solutions was in excellent agreement with the reported experimental solubility of the drug in organic solvents. The analysis of the observed vibrational spectra is consistent with the presence of lidocaine in only one conformation at room temperature. The 1H and 13C NMR spectra of lidocaine were interpreted by experimental and DFT calculated chemical shifts of the drug. The RMSD between experimental and theoretical 1H and 13C chemical shifts for lidocaine is 0.47 and 8.26 ppm, respectively.

  14. Simultaneous cross polarization to 13C and 15N with 1H detection at 60 kHz MAS solid-state NMR

    NASA Astrophysics Data System (ADS)

    Das, Bibhuti B.; Opella, Stanley J.

    2016-01-01

    We describe high resolution MAS solid-state NMR experiments that utilize 1H detection with 60 kHz magic angle spinning; simultaneous cross-polarization from 1H to 15N and 13C nuclei; bidirectional cross-polarization between 13C and 15N nuclei; detection of both amide nitrogen and aliphatic carbon 1H; and measurement of both 13C and 15N chemical shifts through multi-dimensional correlation experiments. Three-dimensional experiments correlate amide 1H and alpha 1H selectively with 13C or 15N nuclei in a polypeptide chain. Two separate three-dimensional spectra correlating 1Hα/13Cα/1HN and 1HN/15N/1Hα are recorded simultaneously in a single experiment, demonstrating that a twofold savings in experimental time is potentially achievable. Spectral editing using bidirectional coherence transfer pathways enables simultaneous magnetization transfers between 15N, 13Cα(i) and 13C‧(i-1), facilitating intra- and inter-residue correlations for sequential resonance assignment. Non-uniform sampling is integrated into the experiments, further reducing the length of experimental time.

  15. Expression, purification, and mass spectrometric analysis of 15N, 13C-labeled RGD-hirudin, expressed in Pichia pastoris, for NMR studies.

    PubMed

    Huang, Yinong; Zhang, Yanling; Wu, Yi; Wang, Jue; Liu, Xingang; Dai, Linsen; Wang, Longsheng; Yu, Min; Mo, Wei

    2012-01-01

    A novel recombinant hirudin, RGD-hirudin, inhibits the activity of thrombin and the aggregation of platelets. Here, we successfully expressed (15)N, (13)C-labeled RGD-hirudin in Pichia pastoris in a fermenter. The protein was subsequently purified to yield sufficient quantities for structural and functional studies. The purified protein was characterized by HPLC and MALDI-TOF mass spectroscopy. Analysis revealed that the protein was pure and uniformly labeled with (15)N and (13)C. A bioassay showed that the anti-thrombin activity and the anti-platelet aggregation ability of the labeled protein were the same as those of unlabeled RGD-hirudin. Multidimensional heteronuclear NMR spectroscopy has been used to determine almost complete backbone (15)N, (13)C and (1)H resonance assignments of the r-RGD-Hirudin. The (15)N-(1)H HSQC spectrum of uniformly (15)N, (13)C-labeled RGD-hirudin allowed successful assignment of the signals. Examples of the quality of the data are provided for the (15)N-(l)H correlation spectrum, and by selected planes of the CBCA(CO)NH, CBCANH, and HNCO experiments. These results provide a basis for further studies on the structure-function relationship of RGD-hirudin with thrombin and platelets. PMID:22879918

  16. Vibrational spectra, monomer, dimer, NBO, HOMO, LUMO and NMR analyses of trans-4-hydroxy-L-proline

    NASA Astrophysics Data System (ADS)

    Xavier, R. John; Dinesh, P.

    2014-07-01

    This work presents the characterization of trans-4-hydroxy-L-proline (abbreviated as THLP) by quantum chemical calculations and spectral techniques. The spectroscopic properties were investigated by FT-IR, FT-Raman and 1H and 13C nuclear magnetic resonance (NMR) techniques. The FT-IR (4000-400 cm-1) and FT-Raman (3500-10 cm-1) spectra in the solid phase were recorded for THLP. The 1H and 13C NMR spectra were recorded in DMSO solution. The energies of THLP are obtained for all the eight conformers form density functional theory (DFT) with 6-311++G(d,p) basis set calculations. From the computational results, C1 conformer is identified as the most stable conformer of THLP. The theoretical wavenumbers were scaled and compared with experimental FT-IR and FT-Raman spectra. The complete assignments were performed on the basis of the experimental results and potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method in terms of fundamental modes. The values of the total dipole moment (μ) and the first order hyperpolarizability (β) of the investigated compound were computed using B3LYP/6-311++G(d,p) calculations. The calculated HOMO-LUMO energies reveal charges transfer occurs within the molecule. The isotropic chemical shift computed by 1H and 13C NMR chemical shifts of the THLF, calculated using the gauge invariant atomic orbital (GIAO) method also shows good agreement with experimental observations.

  17. /sup 13/C NMR analysis of the effects of electron radiation on graphite/polyetherimide composites. Final report

    SciTech Connect

    Ferguson, M.W.

    1989-03-01

    Initial investigations have been made into the use of high resolution nuclear magnetic resonance (NMR) for the characterization of radiation effects in graphite and Kevlar fibers, polymers, and the fiber/matrix interface in graphite/polyetherimide composites. Sample preparation techniques were refined. Essential equipment has been procured. A new NMR probe was constructed to increase the proton signal-to-noise ratio. Problem areas have been identified and plans developed to resolve them.

  18. Glutamatergic and GABAergic energy metabolism measured in the rat brain by (13) C NMR spectroscopy at 14.1 T.

    PubMed

    Duarte, João M N; Gruetter, Rolf

    2013-09-01

    Energy metabolism supports both inhibitory and excitatory neurotransmission processes. This study investigated the specific contribution of astrocytic metabolism to γ-aminobutyric acid (GABA) synthesis and inhibitory GABAergic neurotransmission that remained to be ilucidated in vivo. Therefore, we measured (13)C incorporation into brain metabolites by dynamic (13)C nuclear magnetic resonance spectroscopy at 14.1 T in rats under α-chloralose anaesthesia during infusion of [1,6-(13)C]glucose. The enhanced sensitivity at 14.1 T allowed to quantify incorporation of (13) C into the three aliphatic carbons of GABA non-invasively. Metabolic fluxes were determined with a mathematical model of brain metabolism comprising glial, glutamatergic and GABAergic compartments. GABA synthesis rate was 0.11 ± 0.01 μmol/g/min. GABA-glutamine cycle was 0.053 ± 0.003 μmol/g/min and accounted for 22 ± 1% of total neurotransmitter cycling between neurons and glia. Cerebral glucose oxidation was 0.47 ± 0.02 μmol/g/min, of which 35 ± 1% and 7 ± 1% was diverted to the glutamatergic and GABAergic tricarboxylic acid cycles, respectively. The remaining fraction of glucose oxidation was in glia, where 12 ± 1% of the TCA cycle flux was dedicated to oxidation of GABA. 16 ± 2% of glutamine synthesis was provided to GABAergic neurons. We conclude that substantial metabolic activity occurs in GABAergic neurons and that glial metabolism supports both glutamatergic and GABAergic neurons in the living rat brain. PMID:23745684

  19. The spectroscopic (FT-IR, FT-Raman and NMR), NCA, Fukui function analysis first order hyperpolarizability, TGA of 6-chloro-3,4dihydro-2H-1,2,4-benzothiazine-7-sulphonamide1,1-dioxide by ab initio HF and Density Functional method.

    PubMed

    Elamurugu Porchelvi, E; Muthu, S

    2014-04-01

    The Fourier-Transform Infrared and Fourier-Transform Raman spectra of 6-Chloro-3,4dihydro-2H-1,2,4-benzothiazine-7sulphonamide1,1-dioxide(6CDBSD) was recorded in the region 4000-450cm(-1) and 4000-100cm(-1)respectively. Quantum chemical calculations of energies, geometrical structure and vibrational wave numbers of 6CDBSD were carried out by HF and DFT (B3LYP) method with 6-31G (d,p) basis set. The difference between the observed and scaled wavenumber value of most of the fundamentals is very small. The assignments of the vibrational spectra have been carried out with the aid of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology (SQMFF). The linear polariazability (α) and the first order hyperpolarizability (βtot) values of the investigated molecule have been computed using HF and DFT with 6-31G (d,p) basis set. Stability of the molecule arising from hyper conjugative interaction and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The (1)H and (13)C Nuclear Magnetic Resonance (NMR) chemical shifts of the molecules were calculated using the Gauge-Invariant Atomic orbital (GIAO) method, confirms with the experimental values. The calculated HOMO and LUMO energies also confirm that charge transfer occurs within the molecule. Thermal stability of 6CDBSD was studied by thermo gravimetric analysis (TGA). Next Fukui functions was calculated to identify changes in the reactivity of molecule. Finally molecular electrostatic potential (MEP) and other molecular properties were performed.

  20. Structural studies of pyrido[1,2- c]pyrimidine derivatives by 13C CPMAS NMR, X-ray diffraction and GIAO/DFT calculations

    NASA Astrophysics Data System (ADS)

    Pisklak, Maciej; Król, Marek; Herold, Franciszek; Wolska, Irena; Wawer, Iwona

    2008-12-01

    New 1-aryl- or 1-heteroaryl-piperazinylbutyl derivatives with pyrido[1,2- c]pyrimidine imide moiety, with the expected higher selectivity to 5-HT 1A receptors, have been synthesized. Five hydrochlorides and one base were studied by solid-state 13C CPMAS NMR spectroscopy. 13C chemical shifts indicated that the piperazine ring nitrogen N-1 was protonated. The crystal structure of the base (with 4'F, 3″-CF 3 substituents) was determined by X-ray crystallography. The pyridopyrimidine fragment is essentially planar, and aromatic substituent at C4 is twisted by 59.0°. The crystals are stabilized mainly by the C dbnd O…H sbnd C interactions. The analysis was completed by theoretical calculations of the shielding constants at the GIAO/DFT (B3LYP/6-311+G ∗∗) level.

  1. Solid state structure by X-ray and 13C CP/MAS NMR of new 5-[2-(N,N-dimethylamino)ethoxy]-4,7-dimethylcoumarins

    NASA Astrophysics Data System (ADS)

    Ostrowska, Kinga; Maciejewska, Dorota; Dobrzycki, Łukasz; Socha, Pawel

    2016-05-01

    5-[2-(N,N-dimethylamino)ethoxy]-4,7-dimethylcoumarin (1) and 6-acetyl-5-[2-(N,N-dimethylamino)ethoxy]-4,7-dimethylcoumarin (2), structurally related, were synthesized using both conventional and microwave-assisted approach. An impact of acetyl groups on the molecular structure of coumarin derivatives has been examined. Crystals of 2 were investigated using single crystal and powder X-ray diffraction techniques. Compound 2 crystallizes forming two polymorphs (denoted as 2_1 and 2_2), both belonging to P21/c space group. Both polymorphs are comparably stable and can be formed simultaneously during crystallization process. The solid state structure was also analysed using the fully resolved 13C CP/MAS NMR. The double signals with the intensity ratio of about 1:1 which were observed in the 13C CP/MAS NMR spectrum of compound 1 must arise due to the presence of two conformers of 1. In contrast, NMR spectrum recorded for powder mixture of two polymorphs of compound 2 displays no signal splitting. This is related to structural similarities of molecules in both polymorphs.

  2. Multidimensional solid-state NMR studies of the structure and dynamics of pectic polysaccharides in uniformly 13C-labeled Arabidopsis primary cell walls

    SciTech Connect

    Dick-Perez, Marilu; Wang, Tuo; Salazar, Andre; Zabotina, Olga A.; Hong, Mei

    2012-07-08

    Plant cell wall (CW) polysaccharides are responsible for the mechanical strength and growth of plant cells; however, the high-resolution structure and dynamics of the CW polysaccharides are still poorly understood because of the insoluble nature of these molecules. Here, we use 2D and 3D magic-angle-spinning (MAS) solid-state NMR (SSNMR) to investigate the structural role of pectins in the plant CW. Intact and partially depectinated primary CWs of Arabidopsis thaliana were uniformly labeled with 13C and their NMR spectra were compared. Recent 13C resonance assignment of the major polysaccharides in Arabidopsis thaliana CWs allowed us to determine the effects of depectination on the intermolecular packing and dynamics of the remaining wall polysaccharides. 2D and 3D correlation spectra show the suppression of pectin signals, confirming partial pectin removal by chelating agents and sodium carbonate. Importantly, higher cross peaks are observed in 2D and 3D 13C spectra of the depectinated CW, suggesting higher rigidity and denser packing of the remaining wall polysaccharides compared with the intact CW. 13C spin–lattice relaxation times and 1H rotating-frame spin–lattice relaxation times indicate that the polysaccharides are more rigid on both the nanosecond and microsecond timescales in the depectinated CW. Taken together, these results indicate that pectic polysaccharides are highly dynamic and endow the polysaccharide network of the primary CW with mobility and flexibility, which may be important for pectin functions. This study demonstrates the capability of multidimensional SSNMR to determine the intermolecular interactions and dynamic structures of complex plant materials under near-native conditions. Copyright © 2012 John Wiley & Sons, Ltd.

  3. Probing polymorphism and reactivity in the organic solid state using 13C NMR spectroscopy: Studies of p-Formyl- trans-cinnamic acid

    NASA Astrophysics Data System (ADS)

    Harris, Kenneth D. M.; Thomas, John M.

    1991-09-01

    p-Formyl- trans-cinnamic acid (p-FCA) is known to exist in two different crystal phases (denoted β and γ). When crystals of the β phase of p-FCA are exposed to UV radiation, a solid state dimerization reaction occurs to produce 4,4'-diformyl-β-truxinic acid. In contrast, crystals of the γ phase of p-FCA are photostable. It is shown in this paper that high resolution solid state 13C NMR spectroscopy is a sensitive technique for distinguishing the β and γ phases of p-FCA, and can be used to investigate, in detail, the chemical transformation that occurs upon UV irradiation of the β phase. Specifically, the 13C NMR spectra presented here were recorded using the TOSS (total suppression of sidebands) pulse sequence; this is based upon the standard 13C CPMAS (cross polarization/magic angle sample spinning/high power 1H decoupling) method, but has the additional feature that all orders of spinning sidebands are eliminated from the spectrum. The photoproduct obtained from UV irradiation of β-p-FCA contains a significant noncrystalline component (assessed via powder X-ray diffraction), and our NMR studies suggest that this noncrystalline component of the photoproduct contains some amount of the γ phase of the monomer p-FCA. A mechanism is proposed to explain the fact that UV irradiation of β-p-FCA can generate, in addition to the expected photodimer, an impurity amount of the γ phase of p-FCA.

  4. Carbanion substituent effects on 1-disubstituted 4-(4'-pyridyl)pyridinium methylide structures using 13C NMR spectroscopy and DFT method

    NASA Astrophysics Data System (ADS)

    Depature, Ludovic; Surpateanu, Gheorghe

    2003-11-01

    The structure of 1-disubstituted 4-(4'-pyridyl)pyridinium methylides or 4,4'-bipyridinium monoylides ( 2- 5) with a wide range of carbanion substituents, were determined using 13C NMR signals in dimethylsufoxide (DMSO- d6) solution. For the first time, we developed a systematic determination of 13C NMR chemical shifts of the ylidic carbon using a long-range correlated ( 1H- 13C) HMBC experiments. The chemical shift values are discussed in terms of magnetic and/or electronic effects of the ylidic carbon substituents. From the extracted NMR parameters and the results of accompanying quantum chemical DFT calculations for a three-dimensional (3D)-structure representation, we found a long distance electronic effect where the aromatic heterocycle C2C6 and C4 centers are perturbed according to the electron acceptor strengths of ylidic carbon substituents in all monoylides ( 2- 5c) capable to stabilize in a planar conformation. No significant perturbation on C2C6 and C4 centers are found in all other monoylides ( 2- 5a, b) that adopted a non-planar conformation. Good similar linear dependences of the chemical shift variation Δ (calculated by the differences of analogous C2C6 and C4 chemical shifts in non-planar and planar monoylides) with the ylidic carbon chemical shifts modulated by the strength of electron acceptor substituents pointed out the resonance interaction or the delocalization phenomena of the ylidic carbon charge on the heterocycle.

  5. Secondary structure and side-chain sup 1 H and sup 13 C resonance assignments of calmodulin in solution by heteronuclear multidimensional NMR spectroscopy

    SciTech Connect

    Ikura, Mitsuhiko; Spera, S.; Barbato, G.; Kay, L.E.; Bax, A. ); Krinks, M. )

    1991-09-24

    Heteronuclear 2D and 3D NMR experiments were carried out on recombinant Drosophila calmodulin (CaM), a protein of 148 residues and with molecular mass of 16.7 kDa, that is uniformly labeled with {sup 15}N and {sup 13}C to a level of > 95%. Nearly complete {sup 1}H and {sup 13}C side-chain assignments for all amino acid residues are obtained by using the 3D HCCH-COSY and HCCH-TOCSY experiments that rely on large heteronuclear one-bond scalar couplings to transfer magnetization and establish through-bond connectivities. The secondary structure of this protein in solution has been elucidated by a qualitative interpretation of nuclear Overhauser effects, hydrogen exchange data, and {sup 3}J{sub HNH{alpha}} coupling constants. A clear correlation between the {sup 13}C{alpha} chemical shift and secondary structure is found. The secondary structure in the two globular domains of Drosophila CaM in solution is essentially identical with that of the X-ray crystal structure of mammalian CaM which consists of two pairs of a helix-loop-helix motif in each globular domain. The existence of a short antiparallel {beta}-sheet between the two loops in each domain has been confirmed. The eight {alpha}-helix segments identified from the NMR data are located at Glu-6 to Phe-19, thr-29 to Ser-38, Glu-45 to Glu-54, Phe-65 to Lys-77, Glu-82 to Asp-93, Ala-102 to Asn-111, Asp-118 to Glu-127, and Tyr-138 to Thr-146. Although the crystal structure has a long central helix from Phe-65 to Phe-92 that connects the two globular domains, NMR data indicate that residues Asp-78 to Ser-81 of this central helix adopt a nonhelical conformation with considerable flexibility.

  6. Selective 13C labeling of nucleotides for large RNA NMR spectroscopy using an E. coli strain disabled in the TCA cycle

    PubMed Central

    Thakur, Chandar S.; Sama, Jacob N.; Jackson, Melantha E.; Chen, Bin

    2010-01-01

    Escherichia coli (E. coli) is an ideal organism to tailor-make labeled nucleotides for biophysical studies of RNA. Recently, we showed that adding labeled formate enhanced the isotopic enrichment at protonated carbon sites in nucleotides. In this paper, we show that growth of a mutant E. coli strain DL323 (lacking succinate and malate dehydrogenases) on 13C-2-glycerol and 13C-1,3-glycerol enables selective labeling at many useful sites for RNA NMR spectroscopy. For DL323 E. coli grown in 13C-2-glycerol without labeled formate, all the ribose carbon atoms are labeled except the C3′ and C5′ carbon positions. Consequently the C1′, C2′ and C4′ positions remain singlet. In addition, only the pyrimidine base C6 atoms are substantially labeled to ~96% whereas the C2 and C8 atoms of purine are labeled to ~5%. Supplementing the growth media with 13C-formate increases the labeling at C8 to ~88%, but not C2. Not unexpectedly, addition of exogenous formate is unnecessary for attaining the high enrichment levels of ~88% for the C2 and C8 purine positions in a 13C-1,3-glycerol based growth. Furthermore, the ribose ring is labeled in all but the C4′ carbon position, such that the C2′ and C3′ positions suffer from multiplet splitting but the C5′ position remains singlet and the C1′ position shows a small amount of residual C1′–C2′ coupling. As expected, all the protonated base atoms, except C6, are labeled to ~90%. In addition, labeling with 13C-1,3-glycerol affords an isolated methylene ribose with high enrichment at the C5′ position (~90%) that makes it particularly attractive for NMR applications involving CH2-TROSY modules without the need for decoupling the C4′ carbon. To simulate the tumbling of large RNA molecules, perdeuterated glycerol was added to a mixture of the four nucleotides, and the methylene TROSY experiment recorded at various temperatures. Even under conditions of slow tumbling, all the expected carbon correlations were observed

  7. 1H, 13C, and 15N NMR assignments of StnII-Y111N, a highly impaired mutant of the sea anemone actinoporin Sticholysin II.

    PubMed

    Pardo-Cea, Miguel A; Alegre-Cebollada, Jorge; Martínez-del-Pozo, Alvaro; Gavilanes, José G; Bruix, Marta

    2010-04-01

    Sticholysin II is an actinoporin of 175 amino acids produced by the sea anemone Stichodactyla helianthus. Several studies with different mutants have been performed to characterize its molecular properties and activity. As a first step towards a 3D structural characterization and its interaction with membrane models at a residue level, herein we report the nearly complete NMR (15)N, (13)C and (1)H chemical shifts assignments of the Y111N variant at pH 4.0 and 25 degrees C (BMRB No. 16630). The assignment is complete for the biologically relevant residues, specially for those implicated in membrane interactions.

  8. (1) H and (13) C NMR spectral assignment of N,N'-disubstituted thiourea and urea derivatives active against nitric oxide synthase.

    PubMed

    Chayah, Mariem; Camacho, M Encarnación; Carrión, M Dora; Gallo, Miguel A

    2016-10-01

    The (1) H and (13) C NMR resonances of seventeen N-alkyl and aryl-N'-[3-hydroxy-3-(2-nitro-5-substitutedphenyl)propyl]-thioureas and ureas (1-17), and seventeen N-alkyl or aryl-N'-[3-(2-amino-5-substitutedphenyl)-3-hydroxypropyl]-thioureas and ureas (18-34), designed as NOS inhibitors, were assigned completely using the concerted application of one- and two-dimensional experiments (DEPT, HSQC and HMBC). NOESY studies confirm the preferred conformation of these compounds. Copyright © 2016 John Wiley & Sons, Ltd.

  9. 1H and 13C NMR Chemical Shift Assignments and Conformational Analysis for the Two Diastereomers of the Vitamin K Epoxide Reductase Inhibitor Brodifacoum

    SciTech Connect

    Cort, John R.; Cho, Herman M.

    2009-10-01

    Proton and 13C NMR chemical shift assignments and 1H-1H scalar couplings for the two diastereomers of the vitamin K epoxide reductase (VKOR) inhibitor brodifacoum have been determined from acetone solutions containing both diastereomers. Data were obtained from homo- and heteronuclear correlation spectra acquired at 1H frequencies of 750 and 900 MHz over a 268-303 K temperature range. Conformations inferred from scalar coupling and 1-D NOE measurements exhibit large differences between the diastereomers. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

  10. 13C CPMAS NMR study of the structure of p- t-butylcalix[4]arene-alkylbenzene clathrates in the solid state

    NASA Astrophysics Data System (ADS)

    Yamanobe, Takeshi; Nakamura, Ichinari; Hibino, Kazunobu; Komoto, Ta-i.; Kurosu, Hiromichi; Ando, Isao; Nakamoto, Yoshiaki; Ishida, Shin-ichiro

    1995-08-01

    The NMR chemical shifts measured by the 13C CPMAS method for clathrates of p- t-butylcalix[4]arenes including mobile alkylbenzenes in the solid state revealed that the alkyl groups of the guest molecules are located in the cavity of p- t-butylcalix[4]arene, depending on the size of the alkyl group. It was found that n-alkylbenzenes are easily incorporated into p- t-butylcalix[4]arene in the order of toluene > ethylbenzene ⩾ n-propylbenzene. For isopropylbenzene, the bulky isopropyl group prevents incorporation into the cavity of the host molecule.

  11. Composition and chemical variability of the leaf oil from Corsican Juniperus thurifera. Integrated analysis by GC(RI), GC-MS and 13C NMR.

    PubMed

    Ottavioli, Josephine; Casanova, Joseph; Bighelli, Ange

    2010-12-01

    The composition of 16 samples of leaf oil from Corsican Juniperus thurifera was investigated by integrated techniques, GC, GC-MS and 13C NMR. K-means partitioning and PCA analysis of the data allowed the definition of a main group (14 samples) dominated by limonene (mean = 52.2%, SD = 6.4) and alpha-pinene (mean = 7.2%, SD = 3.8). Limonene and beta-elemol (up to 19.7%) were identified as the major components of two atypic samples.

  12. Observation of cytoplasmic and vacuolar malate in maize root tips by sup 13 C-NMR spectroscopy. [Zea mays L

    SciTech Connect

    Chang, K.; Roberts, J.K.M. )

    1989-01-01

    The accumulation of malate by maize (Zea mays L.) root tips perfused with KH{sup 13}CO{sub 3} was followed by {sup 13}C nuclear magnetic resonance spectroscopy. In vivo nuclear magnetic resonance spectra contained distinct signals from two pools of malate in maize root tips, one at a pH {approximately}5.3 (assigned to the vacuole) and one at a pH > 6.5 (assigned to the cytoplasm). The ratio of cytoplasmic to vacuolar malate was lower in 12 millimeter long root tips than in 2 millimeter root tips. The relatively broad width of the signals from C1- and C4-labeled vacuolar malate indicated heterogeneity in vacuolar pH. During the 3 hour KH{sup 13}CO{sub 3} treatment, {sup 13}C-malate accumulated first primarily in the cytoplasm, increasing to a fairly constant level of {approximately}6 millimolar by 1 hour. After a lag, vacuolar malate increased throughout the experiment.

  13. Molecular interactions of a model bile salt and porcine bile with (1,3:1,4)-β-glucans and arabinoxylans probed by (13)C NMR and SAXS.

    PubMed

    Gunness, Purnima; Flanagan, Bernadine M; Mata, Jitendra P; Gilbert, Elliot P; Gidley, Michael J

    2016-04-15

    Two main classes of interaction between soluble dietary fibres (SDFs), such as (1,3:1,4)-β-D-glucan (βG) and arabinoxylan (AX) and bile salt (BS) or diluted porcine bile, were identified by (13)C NMR and small angle X-ray scattering (SAXS). Small chemical shift differences of BS NMR resonances were consistent with effective local concentration or dilution of BS micelles mostly by βG, suggesting dynamic interactions; whilst the reduced line widths/intensities observed were mostly caused by wheat AX and the highest molecular size and concentrations of βG. SAXS showed evidence of changes in βG but not AX in the presence of BS micelles, at >13 nm length scale consistent with molecular level interactions. Thus intermolecular interactions between SDF and BS depend on both SDF source and its molecular weight and may occur alone or in combination. PMID:26617003

  14. Complete 1H and 13C NMR assignments of three new polyhydroxylated sterols from the South China Sea gorgonian Subergorgia suberosa.

    PubMed

    Qi, Shu-Hua; Zhang, Si; Wang, Yi-Fei; Li, Ming-Yi

    2007-12-01

    Three new polyhydroxylated sterols, 3beta,6alpha,11,20beta,24-pentahydroxy- 9,11-seco-5alpha-24-ethylcholest-7,28-diene-9-one (1), 3-(1',2'-ethandiol)-24- methylcholest-8(9),22E-diene-3beta,5alpha,6alpha,7alpha,11alpha-pentaol (2), 24-methylcholest-7,22 E-diene-3beta,5alpha,6beta,25-tetraol (3) together with five known sterols, were isolated from the EtOH/CH2Cl2 extract of the South China Sea gorgonian Subergorgia suberosa. The complete assignments of the 1H and 13C NMR chemical shifts for these new compounds were achieved by means of 1D and 2D NMR techniques, including HSQC, HMBC, 1H--1H COSY, and NOESY spectra.

  15. Solution Structures of the Prototypical 18 kDa Translocator Protein Ligand, PK 11195, Elucidated with 1H/13C NMR Spectroscopy and Quantum Chemistry

    PubMed Central

    2012-01-01

    Eighteen kilodalton translocator protein (TSPO) is an important target for drug discovery and for clinical molecular imaging of brain and peripheral inflammatory processes. PK 11195 [1a; 1-(2-chlorophenyl)-N-methyl-(1-methylpropyl)-3-isoquinoline carboxamide] is the major prototypical high-affinity ligand for TSPO. Elucidation of the solution structure of 1a is of interest for understanding small-molecule ligand interactions with the lipophilic binding site of TSPO. Dynamic 1H/13C NMR spectroscopy of 1a revealed four quite stable but interconverting rotamers, due to amide bond and 2-chlorophenyl group rotation. These rotamers have been neglected in previous descriptions of the structure of 1a and of the binding of 1a to TSPO. Here, we used quantum chemistry at the level of B3LYP/6-311+G(2d,p) to calculate 13C and 1H chemical shifts for the rotamers of 1a and for the very weak TSPO ligand, N-desmethyl-PK 11195 (1b). These data, plus experimental NMR data, were then used to characterize the structures of rotamers of 1a and 1b in organic solution. Energy barriers for both the amide bond and 2′-chlorophenyl group rotation of 1a were determined from dynamic 1H NMR to be similar (ca.17 to 18 kcal/mol), and they compared well with those calculated at the level of B3LYP/6-31G*. Furthermore, the computed barrier for Z to E rotation is considerably lower in 1a(18.7 kcal/mol) than in 1b (25.4 kcal/mol). NMR (NOE) unequivocally demonstrated that the E rotamer of 1a is the more stable in solution by about 0.4 kcal/mol. These detailed structural findings will aid future TSPO ligand design and support the notion that TSPO prefers to bind ligands as amide E-rotamers. PMID:22860199

  16. 13C NMR and fluorescence analysis of tryptophan dynamics in wild-type and two single-Trp variants of Escherichia coli thioredoxin.

    PubMed Central

    Kemple, M D; Yuan, P; Nollet, K E; Fuchs, J A; Silva, N; Prendergast, F G

    1994-01-01

    The rotational motion of tryptophan side chains in oxidized and reduced wild-type (WT) Escherichia coli thioredoxin and in two single-tryptophan variants of E. coli thioredoxin was studied in solution in the temperature range 20-50 degrees C from 13C-NMR relaxation rate measurements at 75.4 and 125.7 MHz and at 20 degrees C from steady-state and time-resolved trp fluorescence anisotropy measurements. Tryptophan enriched with 13C at the delta 1 and epsilon 3 sites of the indole ring was incorporated into WT thioredoxin and into two single-trp mutants, W31F and W28F, in which trp-28 or trp-31 of WT thioredoxin was replaced, respectively, with phenylalanine. The NMR relaxation data were interpreted using the Lipari and Szabo "model-free" approach (G. Lipari and A. Szabo. 1982. J. Amer. Chem. Soc. 104:4546-4559) with trp steady-state anisotropy data included for the variants at 20 degrees C. Values for the correlation time for the overall rotational motion (tau m) from NMR of oxidized and reduced WT thioredoxin at 35 degrees C agree well with those given by Stone et al. (Stone, M. J., K. Chandrasekhar, A. Holmgren, P. E. Wright, and H. J. Dyson. 1993. Biochemistry. 32:426-435) from 15N NMR relaxation rates, and the dependence of tau m on viscosity and temperature was in accord with the Stokes-Einstein relationship. Order parameters (S2) near 1 were obtained for the trp side chains in the WT proteins even at 50 degrees C. A slight increase in the amplitude of motion (decrease in S2) of trp-31, which is near the protein surface, but not of trp-28, which is partially buried in the protein matrix, was observed in reduced relative to oxidized WT thioredoxin. For trp-28 in W31F, order parameters near 1 (S2 > or = 0.8) at 20 degrees C were found, whereas trp-31 in W28F yielded the smallest order parameters (S2 approximately 0.6) of any of the cases. Analysis of time-resolved anisotropy decays in W28F and W31F yielded S2 values in good agreement with NMR, but gave tau m values

  17. Generation of chemical movies: FT-IR spectroscopic imaging of segmented flows.

    PubMed

    Chan, K L Andrew; Niu, X; deMello, A J; Kazarian, S G

    2011-05-01

    We have previously demonstrated that FT-IR spectroscopic imaging can be used as a powerful, label-free detection method for studying laminar flows. However, to date, the speed of image acquisition has been too slow for the efficient detection of moving droplets within segmented flow systems. In this paper, we demonstrate the extraction of fast FT-IR images with acquisition times of 50 ms. This approach allows efficient interrogation of segmented flow systems where aqueous droplets move at a speed of 2.5 mm/s. Consecutive FT-IR images separated by 120 ms intervals allow the generation of chemical movies at eight frames per second. The technique has been applied to the study of microfluidic systems containing moving droplets of water in oil and droplets of protein solution in oil. The presented work demonstrates the feasibility of the use of FT-IR imaging to study dynamic systems with subsecond temporal resolution. PMID:21438630

  18. 13C NMR studies of gluconeogenesis in rat liver cells: Utilization of labeled glycerol by cells from euthyroid and hyperthyroid rats

    PubMed Central

    Cohen, S. M.; Ogawa, S.; Shulman, R. G.

    1979-01-01

    The gluconeogenic pathway from [2-13C]glycerol and [1,3-13C]glycerol has been followed in suspensions of isolated rat hepatocytes at 25°C by 13C NMR at 90.5 MHz. The flow of label through the major pathway from glycerol to L-glycerol 3-phosphate and into glucose was followed in cells from control and triiodothyronine-treated rats. Treatment increased the rates of glucose formation and glycerol consumption 2-fold and decreased the αGP level to 40%. We calculate that ≈60% of the flux is through the mitochondrial glycerol phosphate dehydrogenase in cells from triiodothyronine-treated rats, compared with ≈15% in cells from the controls. Equal distribution of label between the trioses of glucose was obtained and, because the C3-C4 spin-spin coupling gives the distribution of labeled carbons in the same molecule, it was possible to measure the amount of triose from unlabeled fructose incorporated into the glucose labeled at carbons 1, 3, 4, and 6. About 10% of the hexoses had flowed through the pentose cycle and back into the hexose pathway in cells from fasted rats. From the distribution of label at glucose carbons not labeled via the major pathway and from the carbon spin-spin splitting patterns observed, we conclude that transketolase is reversible whereas transaldolase is essentially irreversible in the nonoxidative pentose branch. PMID:287001

  19. Solid-state 13C NMR studies of a large fossil gymnosperm from the Yallourn Open Cut, Latrobe Valley, Australia

    USGS Publications Warehouse

    Bates, A.L.; Hatcher, P.G.

    1989-01-01

    A series of samples taken from the cross section of a 3-m-diameter fossilized gymnospermous log (Araucariaceae) in the Yallourn Seam of the Australian brown coals was examined by solid state 13C nuclear magnetic resonance to delineate chemical changes related to the combined processes of peatification and coalification. The results show that cellulosic materials were degraded and lost on the periphery of the log, however, the degree of such degradation in the central core is substantially less. The lignin is uniformly altered by coalification reactions to a macromolecular substance displaying decreased aryl ether linkages but significantly greater amounts of carbon linkages compared to modern lignin. Changes in the methoxyl carbon contents of lignin in cross section reveal demethylation reactions, but these do not appear to be related to degree of carbon linking. Both the degredation of cellulosic materials and demethylation of lignin appear to be early diagenetic processes occurring during peatification independently of the coalification reactions. ?? 1989.

  20. A comparison of dissolved humic substances from seawater with Amazon River counterparts by sup 13 C-NMR spectrometry

    SciTech Connect

    Hedges, J.I. ); Hatcher, P.G. ); Ertel, J.R. ); Meyers-Schulte, K.J. )

    1992-04-01

    Although dissolved organic matter (DOM) in seawater constitutes one of the major reservoirs of reduced carbon on earth, the biochemical and geographic origins of this material and its hydrophobic humic component remain unclear. Rivers have been suggested as a potentially important source of marine DOM, but this implication has not yet been systematically tested by direct comparisons of the bulk structural characteristics of DOM isolated from representative ocean reservoirs and their major river sources. The authors report here such a comparison and find that dissolved humic substances isolated from surface and deep seawater in the East Equatorial and north Central Pacific are enriched in nitrogen and {sup 13}C and depleted in unsaturated carbon with respect to counterparts from the Amazon River system. Based on these observations, riverine dissolved humic substances appear to comprise a small fraction of seawater humic substances and therefore must be efficiently and rapidly removed from the ocean.

  1. Automated feature extraction for the classification of human in vivo 13C NMR spectra using statistical pattern recognition and wavelets.

    PubMed

    Tate, A R; Watson, D; Eglen, S; Arvanitis, T N; Thomas, E L; Bell, J D

    1996-06-01

    If magnetic resonance spectroscopy (MRS) is to become a useful tool in clinical medicine, it will be necessary to find reliable methods for analyzing and classifying MRS data. Automated methods are desirable because they can remove user bias and can deal with large amounts of data, allowing the use of all the available information. In this study, techniques for automatically extracting features for the classification of MRS in vivo data are investigated. Among the techniques used were wavelets, principal component analysis, and linear discriminant function analysis. These techniques were tested on a set of 75 in vivo 13C spectra of human adipose tissue from subjects from three different dietary groups (vegan, vegetarian, and omnivore). It was found that it was possible to assign automatically 94% of the vegans and omnivores to their correct dietary groups, without the need for explicit identification or measurement of peaks.

  2. Unique Backbone-Water Interaction Detected in Sphingomyelin Bilayers with 1H/31P and 1H/13C HETCOR MAS NMR Spectroscopy

    PubMed Central

    Holland, Gregory P.; Alam, Todd M.

    2008-01-01

    Two-dimensional 1H/31P dipolar heteronuclear correlation (HETCOR) magic-angle spinning nuclear magnetic resonance (NMR) is used to investigate the correlation of the lipid headgroup with various intra- and intermolecular proton environments. Cross-polarization NMR techniques involving 31P have not been previously pursued to a great extent in lipid bilayers due to the long 1H-31P distances and high degree of headgroup mobility that averages the dipolar coupling in the liquid crystalline phase. The results presented herein show that this approach is very promising and yields information not readily available with other experimental methods. Of particular interest is the detection of a unique lipid backbone-water intermolecular interaction in egg sphingomyelin (SM) that is not observed in lipids with glycerol backbones like phosphatidylcholines. This backbone-water interaction in SM is probed when a mixing period allowing magnetization exchange between different 1H environments via the nuclear Overhauser effect (NOE) is included in the NMR pulse sequence. The molecular information provided by these 1H/31P dipolar HETCOR experiments with NOE mixing differ from those previously obtained by conventional NOE spectroscopy and heteronuclear NOE spectroscopy NMR experiments. In addition, two-dimensional 1H/13C INEPT HETCOR experiments with NOE mixing support the 1H/31P dipolar HETCOR results and confirm the presence of a H2O environment that has nonvanishing dipolar interactions with the SM backbone. PMID:18390621

  3. Magnetic resonance spectroscopy and metabolism. Applications of proton and 13C NMR to the study of glutamate metabolism in cultured glial cells and human brain in vivo.

    PubMed

    Portais, J C; Pianet, I; Allard, M; Merle, M; Raffard, G; Kien, P; Biran, M; Labouesse, J; Caille, J M; Canioni, P

    1991-01-01

    Nuclear magnetic resonance (NMR) spectroscopy was used to study the metabolism of cells from the central nervous system both in vitro on perchloric acid extracts obtained either from cultured tumoral cells (C6 rat glioma) or rat astrocytes in primary culture, and in vivo within the human brain. Analysis of carbon 13 NMR spectra of perchloric acid extracts prepared from cultured cells in the presence of NMR [1-13C] glucose as substrate allowed determination of the glutamate and glutamine enrichments in both normal and tumoral cells. Preliminary results indicated large changes in the metabolism of these amino acids (and also of aspartate and alanine) in the C6 cell as compared to its normal counterpart. Localized proton NMR spectra of the human brain in vivo were obtained at 1.5 T, in order to evaluate the content of various metabolites, including glutamate, in peritumoral edema from a selected volume of 2 x 2 x 2 cm3. N-acetyl aspartate, glutamate, phosphocreatine, creatine, choline and inositol derivative resonances were observed in 15 min spectra. N-acetyl-aspartate was found to be at a lower level in contrast to glutamate which was detected at a higher level in the injured area as compared to the contralateral unaffected side. PMID:1674432

  4. Mathematical models for determining metabolic fluxes through the citric acid and the glyoxylate cycles in Saccharomyces cerevisiae by 13C-NMR spectroscopy.

    PubMed

    Tran-Dinh, S; Bouet, F; Huynh, Q T; Herve, M

    1996-12-15

    We propose, first, a practical method for studying the isotopic transformation of glutamate or any other metabolite isotopomers in the citric acid and the glyoxylate cycles; second, two mathematical models, one for evaluating the flux through the citric acid cycle and the other for evaluating the flux through the latter coupled to the glyoxylate cycle in yeast. These models are based on the analysis of 13C-NMR spectra of glutamate obtained from Saccharomyces cerevisiae, NCYC strain, fed with 100% enriched [2-13C]acetate. The population of each glutamate isotopomer, the change in intensity of each multiplet component or the enrichment of any glutamate carbon is expressed by a specific analytical equation from which the flux in the citric acid and the glyoxylate cycles can be deduced. The aerobic metabolism of 100% [2-13C]acetate in acetate-grown S. cerevisiae cells was studied as a function of time using 13C-NMR. 1H-NMR and biochemical techniques. The C1 and C6 doublet and singlet of labeled trehalose increase continuously with time indicating that there is no isotopic transformation between trehalose isotopomers even though the corresponding formation rates are different. By contrast, the glutamate C4 singlet increases then decreases with time. The C4 doublet, which is lower than the singlet for t < 60 min, increases continuously and becomes higher than the singlet for t > 90 min. A similar observation was made for the C2 resonance singlet and doublet. In addition, the glutamate C2 multiplet consists of only seven instead of nine peaks as in random labeling. These results agree well with our models and demonstrate that, in the presence of acetate, anaplerotic carbon sources involved in the synthesis of acetyl-CoA are negligible in yeast. The flux in the citric acid cycle was deduced from a plot of the C4 area versus incubation time, while the flux within the glyoxylate cycle was determined from the relative intensity of the glutamate C4 doublet and singlet. The

  5. Residue specific hydration of primary cell wall potato pectin identified by solid-state 13C single-pulse MAS and CP/MAS NMR spectroscopy.

    PubMed

    Larsen, Flemming H; Byg, Inge; Damager, Iben; Diaz, Jerome; Engelsen, Søren B; Ulvskov, Peter

    2011-05-01

    Hydration of rhamnogalacturonan-I (RG-I) derived from potato cell wall was analyzed by (13)C single-pulse (SP) magic-angle-spinning (MAS) and (13)C cross-polarization (CP) MAS nuclear magnetic resonance (NMR) and supported by (2)H SP/MAS NMR experiments. The study shows that the arabinan side chains hydrate more readily than the galactan side chains and suggests that the overall hydration properties can be controlled by modifying the ratio of these side chains. Enzymatic modification of native (NA) RG-I provided samples with reduced content of arabinan (sample DA), galactan (sample DG), or both side chains (sample DB). Results of these samples suggested that hydration properties were determined by the length and character of the side chains. NA and DA exhibited similar hydration characteristics, whereas DG and DB were difficult to hydrate because of the less hydrophilic properties of the rhamnose-galacturonic acid (Rha-GalA) backbone in RG-I. Potential food ingredient uses of RG-I by tailoring of its structure are discussed.

  6. Construction and 13C NMR signal-amplification efficiency of a dynamic nuclear polarizer at 6.4 T and 1.4 K

    NASA Astrophysics Data System (ADS)

    Kiswandhi, Andhika; Niedbalski, Peter; Parish, Christopher; Ferguson, Sarah; Taylor, David; McDonald, George; Lumata, Lloyd

    Dissolution dynamic nuclear polarization (DNP) is a rapidly emerging technique in biomedical and metabolic imaging since it amplifies the liquid-state nuclear magnetic resonance (NMR) and imaging (MRI) signals by >10,000-fold. Originally used in nuclear scattering experiments, DNP works by creating a non-Boltzmann nuclear spin distribution by transferring the high electron (γ = 28,000 MHz/T) thermal polarization to the nuclear spins via microwave irradiation of the sample at high magnetic field and low temperature. A dissolution device is used to rapidly dissolve the frozen sample and consequently produces an injectable ``hyperpolarized'' liquid at physiologically-tolerable temperature. Here we report the construction and performance evaluation of a dissolution DNP hyperpolarizer at 6.4 T and 1.4 K using a continuous-flow cryostat. The solid and liquid-state 13C NMR signal enhancement levels of 13C acetate samples doped with trityl OX063 and 4-oxo-TEMPO free radicals will be discussed and compared with the results from the 3.35 T commercial hyperpolarizer. This work is supported by US Dept of Defense Award No. W81XWH-14-1-0048 and Robert A. Welch Foundation Grant No. AT-1877.

  7. Mechanism of Au(III) reduction by chitosan: comprehensive study with 13C and 1H NMR analysis of chitosan degradation products.

    PubMed

    Pestov, Alexander; Nazirov, Alexander; Modin, Evgeny; Mironenko, Alexander; Bratskaya, Svetlana

    2015-03-01

    The mechanism of Au(III) reduction by chitosan has been proposed on the basis of comprehensive study of kinetics of Au(III) reduction and chitosan chain degradation using UV-vis spectroscopy and viscosimetry, and identification of reaction products using colloid titration and (13)C, (1)H NMR spectroscopy. We have shown that formation of gold nanoparticles in H[AuCl4]/chitosan solutions starts with hydrolysis of chitosan catalyzed by Au(III). The products of chitosan hydrolysis rather than chitosan itself act as the main reducing species. According to (13)C and (1)H NMR spectroscopy data, chitosan/Au(0) composites contain chitosan with reduced molecular weight and acetylation degree, whereas water-soluble by-products consist of chitosan oligomers with higher acetylation degree, derivatives of glucosamine acids, and formate ion. Chitosan degradation has significantly contributed to the decrease of its efficiency as a gold nanoparticles stabilizer. The gold particle size increased from 6.9 nm to 16.2 nm, when Au(III)/chitosan molar ratio changed from 1:80 to 1:10.

  8. Backbone 1H, 13C, and 15N NMR assignments for the Cyanothece 51142 protein cce_0567: a protein associated with nitrogen fixation in the DUF683 family

    SciTech Connect

    Buchko, Garry W.; Sofia, Heidi J.

    2008-06-01

    The recently sequenced genome of the diurnal cyanobacterium Cyanothece sp. PCC 51142 (contig 83.1_1_243_746) contains the sequence for an hypothetical protein that falls into the DUF683 family. As observed for the other 54 DUF683 proteins currently listed in the GenBank database, this 78-residue (9.0 kDa) protein in Cyanothece is also found in a nitrogen fixation gene cluster suggesting that it is involved in the process. To date no structural information exists for any of the proteins in the DUF683 family. In an effort to elucidate the biochemical role DUF683 may play in nitrogen fixation and to obtain structural information for a member of the DUF683 protein family, a construct containing DUF683 from Cyanothece 51142 was generated, expressed, purified, and the solution properties characterized. A total rotational correlation time (tc) of 17.1 ns was estimated by nuclear magnetic resonance (NMR) spectroscopy suggesting a molecular weight of ~ 40 kDa, an observation dictating that DUF683 is a tetramer in solution. Using triple-labeled (2H, 13C, 15N) and residue-specific 15N-labeled amino acids (L, K, V, and E/Q) samples, most of the backbone and side chain resonances for DUF683 were assigned. The 13C alpha chemical shifts and NOESY NMR data indicate that the protein is helical from K18-E75.

  9. Backbone dynamics of a model membrane protein: 13C NMR spectroscopy of alanine methyl groups in detergent-solubilized M13 coat protein.

    PubMed

    Henry, G D; Weiner, J H; Sykes, B D

    1986-02-11

    The filamentous coliphage M13 possesses multiple copies of a 50-residue coat protein which is inserted into the inner membrane of Escherichia coli during infection. 13C nuclear magnetic resonance (NMR) spectroscopy has been used to probe the structure and dynamics of M13 coat protein solubilized in detergent micelles. A comparison of backbone dynamics within the hydrophobic core region and the hydrophilic terminal domains was obtained by biosynthetic incorporation of [3-13C]alanine. Alanine is distributed throughout the protein and accounts for 10 residues (i.e., 20% of the total). Similar 13C NMR spectra of the protein have been obtained in two anionic detergents, sodium deoxycholate and sodium dodecyl sulfate, although the structures and physical properties of these solubilizing agents are quite different. The N-terminal alanine residues, assigned by pH titration, and the penultimate residue, assigned by carboxypeptidase A digestion, give rise to analogous peaks in both detergent systems. The pKa of Ala-1 (approximately 8.8) and the relaxation parameters of individual carbon atoms (T1, T2, and the nuclear Overhauser enhancement) are also generally similar, suggesting a similarity in the overall protein structure. Relaxation data have been analyzed according to the model-free approach of Lipari and Szabo [Lipari, G., & Szabo, A. (1982) J. Am. Chem. Soc. 104, 4546-4559]. The overall correlation times were obtained by fitting the three experimental relaxation values for a given well-resolved single carbon atom to obtain a unique value for the generalized order parameter, S2, and the effective correlation time, tau e. The former parameter reflects the spatial restriction of motion, and the latter, the rate.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Structural characterization and molecular order of rodlike mesogens with three- and four-ring core by XRD and 13C NMR spectroscopy.

    PubMed

    Reddy, M Kesava; Reddy, K Subramanyam; Yoga, K; Prakash, M; Narasimhaswamy, T; Mandal, A B; Lobo, Nitin P; Ramanathan, K V; Rao, D S Shankar; Prasad, S Krishna

    2013-05-01

    Structural characterizations using XRD and (13)C NMR spectroscopy of two rodlike mesogens consisting of (i) three phenyl ring core with a polar cyano terminal and (ii) four phenyl ring core with flexible dodecyl terminal chain are presented. The three-ring-core mesogen with cyano terminal exhibits enantiotropic smectic A phase while the four-ring mesogen reveals polymesomorphism and shows enantiotropic nematic, smectic C, and tilted hexatic phases. The molecular organization in the three-ring mesogen is found to be partial bilayer smectic Ad type, and the interdigitation of the molecules in the neighboring layers is attributed to the presence of the polar terminal group. For the four-ring mesogen, the XRD results confirm the existence of the smectic C and the tilted hexatic mesophases. A thermal variation of the layer spacing across the smectic C phase followed by a discrete jump at the transition to the tilted hexatic phase is also observed. The tilt angles have been estimated to be about 45° in the smectic C phase and about 40° in tilted hexatic phase. (13)C NMR results indicate that in the mesophase the molecules are aligned parallel to the magnetic field. From the (13)C-(1)H dipolar couplings determined from the 2D experiments, the overall order parameter for the three-ring mesogen in its smectic A phase has been estimated to be 0.72 while values ranging from 0.88 to 0.44 have been obtained for the four-ring mesogen as it passes from the tilted hexatic to the nematic phase. The orientations of the different rings of the core unit with respect to each other and also with respect to the long axis of the molecule have also been obtained. PMID:23627902

  11. Introducing NMR to a General Chemistry Audience: A Structural-Based Instrumental Laboratory Relating Lewis Structures, Molecular Models, and [superscript 13]C NMR Data

    ERIC Educational Resources Information Center

    Pulliam, Curtis R.; Pfeiffer, William F.; Thomas, Alyssa C.

    2015-01-01

    This paper describes a first-year general chemistry laboratory that uses NMR spectroscopy and model building to emphasize molecular shape and structure. It is appropriate for either a traditional or an atoms-first curriculum. Students learn the basis of structure and the use of NMR data through a cooperative learning hands-on laboratory…

  12. Trace level detection of compounds related to the chemical weapons convention by 1H-detected 13C NMR spectroscopy executed with a sensitivity-enhanced, cryogenic probehead.

    PubMed

    Cullinan, David B; Hondrogiannis, George; Henderson, Terry J

    2008-04-15

    Two-dimensional 1H-13C HSQC (heteronuclear single quantum correlation) and fast-HMQC (heteronuclear multiple quantum correlation) pulse sequences were implemented using a sensitivity-enhanced, cryogenic probehead for detecting compounds relevant to the Chemical Weapons Convention present in complex mixtures. The resulting methods demonstrated exceptional sensitivity for detecting the analytes at trace level concentrations. 1H-13C correlations of target analytes at < or = 25 microg/mL were easily detected in a sample where the 1H solvent signal was approximately 58,000-fold more intense than the analyte 1H signals. The problem of overlapping signals typically observed in conventional 1H spectroscopy was essentially eliminated, while 1H and 13C chemical shift information could be derived quickly and simultaneously from the resulting spectra. The fast-HMQC pulse sequences generated magnitude mode spectra suitable for detailed analysis in approximately 4.5 h and can be used in experiments to efficiently screen a large number of samples. The HSQC pulse sequences, on the other hand, required roughly twice the data acquisition time to produce suitable spectra. These spectra, however, were phase-sensitive, contained considerably more resolution in both dimensions, and proved to be superior for detecting analyte 1H-13C correlations. Furthermore, a HSQC spectrum collected with a multiplicity-edited pulse sequence provided additional structural information valuable for identifying target analytes. The HSQC pulse sequences are ideal for collecting high-quality data sets with overnight acquisitions and logically follow the use of fast-HMQC pulse sequences to rapidly screen samples for potential target analytes. Use of the pulse sequences considerably improves the performance of NMR spectroscopy as a complimentary technique for the screening, identification, and validation of chemical warfare agents and other small-molecule analytes present in complex mixtures and environmental

  13. HCN, A Triple-Resonance NMR Technique for Selective Observation of Histidine and Tryptophan Side Chains in 13C/ 15N-Labeled Proteins

    NASA Astrophysics Data System (ADS)

    Sudmeier, James L.; Ash, Elissa L.; Günther, Ulrich L.; Luo, Xuelian; Bullock, Peter A.; Bachovchin, William W.

    1996-12-01

    HCN, a new 3D NMR technique for stepwise coherence transfer from1H to13C to15N and reverse through direct spin couplings1JCHand1JCN, is presented as a method for detection and assignment of histidine and tryptophan side-chain1H,13C, and15N resonances in uniformly13C/15N-labeled proteins. Product-operator calculations of cross-peak volumes vs adjustable delay τ3were employed for determination of optimal τ3. For the phosphatidylinositol 3-kinase (PI3K SH3 domain, MW = 9.6 kD) at pH 6, H(C)N, the1H/15N projection, produced observable cross peaks within 20 min. and was completely selective for the single tryptophan and single histidine. The 3D HCN experiment yielded well-defined cross peaks in 20 h for the13C/15N-labeled origin-specific DNA binding domain from simian virus 40 T-antigen (T-ag-OBD131-259, MW = 15.4 kD) at pH 5.5. Resonances from all six histidines in T-ag-OBD were observed, and 11 of the 121H and13C chemical shifts and 10 of the 1215N chemical shifts were determined. The13C dimension proved essential in assignment of the multiply overlapping1H and15N resonances. From the spectra recorded at a single pH, three of the imidazoles were essentially neutral and the other three were partially protonated (22-37%). HCN yielded strong cross pea