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Sample records for aromatic schiff base

  1. Charge-transfer complexes of pyrimidine Schiff bases with aromatic nitro compounds

    NASA Astrophysics Data System (ADS)

    Issa, Yousry M.; El Ansary, A. L.; Sherif, O. E.; Hassib, H. B.

    2011-08-01

    Charge-transfer (CT) complexes of pyrimidine Schiff bases, derived from condensation of 2-aminopyrimidine and substituted benzaldehydes, with some aromatic polynitro compounds were prepared and investigated using IR, UV, visible and 1H NMR spectroscopy. For all solid complexes, the main interaction between the donor and acceptor molecules takes place through the ?-?* interaction. Strong and some weak acidic acceptors, in addition interact through proton transfer from the acceptor molecule to the basic centre of the electron donor. Also, an n-?* transition was detected in some complexes.

  2. Charge-transfer complexes of pyrimidine Schiff bases with aromatic nitro compounds.

    PubMed

    Issa, Yousry M; el-Ansary, A L; Sherif, O E; Hassib, H B

    2011-08-01

    Charge-transfer (CT) complexes of pyrimidine Schiff bases, derived from condensation of 2-aminopyrimidine and substituted benzaldehydes, with some aromatic polynitro compounds were prepared and investigated using IR, UV, visible and (1)H NMR spectroscopy. For all solid complexes, the main interaction between the donor and acceptor molecules takes place through the ?-?* interaction. Strong and some weak acidic acceptors, in addition interact through proton transfer from the acceptor molecule to the basic centre of the electron donor. Also, an n-?* transition was detected in some complexes. PMID:21531169

  3. Synthesis, Spectral, and Biological Properties of Copper(II) Complexes of Thiosemicarbazones of Schiff Bases Derived from 4-Aminoantipyrine and Aromatic Aldehydes

    PubMed Central

    Agarwal, Ram K.; Singh, Lakshman; Sharma, Deepak Kumar

    2006-01-01

    We have synthesized a novel series of Schiff bases by condensation of 4-aminoantipyrine and various aromatic aldehydes followed by reaction with thiosemicarbazide. These thiosemicarbazones are potential ligands toward transition metal ions. The reaction of copper(II) salts with 4[N-(benzalidene)amino]antipyrinethiosemicarbazone (BAAPTS), 4[N-(4?-methoxybenzalidene) amino] antipyrinethiosemicarbozone (MBAAPTS), 4[N-(4?-dimethylamino benzalidene) amino] antipyrinethiosemicarbazone (DABAAPTS), and 4[N-(cinnamalidene) amino] antipyrinethiosemicarbazone (CAAPTS) resulted in the formation of solid complexes with the general composition CuX2 (H2O)(L)(X = Cl, Br,NO3,NCS, or CH3COO; L = BAAPTS, MBAAPTS, DABAAPTS, or CAAPTS). These complexes were characterized through elemental analysis, molecular weight, electrical conductance, infrared, electronic spectra, and magnetic susceptibilities at room temperature. Copper(II) complexes with BAAPTS and MBAAPTS were screened for antibacterial and antifungal properties and have exhibited potential activity. Thermal stabilities of two representative complexes were also investigated. PMID:17497009

  4. Anomeric and tautomeric equilibria in D-2-glucosamine Schiff bases

    NASA Astrophysics Data System (ADS)

    Ko?odziej, B.; Grech, E.; Schilf, W.; Kamie?ski, B.; Makowski, M.; Rozwadowski, Z.; Dziembowska, T.

    2007-11-01

    The structure of some glucosamine Schiff bases has been studied by means of ab initio RHF and DFT calculation and CP/MAS 13C and 15N NMR measurements. The anomeric and tautomeric equilibria in a DMSO solution have been studied by 1H, 13C and 15N NMR spectroscopy. The anomeric composition of D-2-glucosamine Schiff bases in the solid state and in DMSO solution has been shown to depends on the tautomeric form of Schiff bases and electronic properties of substituents on the aromatic ring.

  5. Asymmetric Schiff bases derived from diaminomaleonitrile and their metal complexes

    NASA Astrophysics Data System (ADS)

    Yang, Jianjie; Shi, Rufei; Zhou, Pei; Qiu, Qiming; Li, Hui

    2016-02-01

    Asymmetric Schiff bases, due to its asymmetric structure, can be used as asymmetric catalyst, antibacterial, and mimic molecules during simulate biological processes, etc. In recent years, research on synthesis and properties of asymmetric Schiff bases have become an increase interest of chemists. This review summarizes asymmetric Schiff bases derived from diaminomaleonitrile (DAMN) and DAMN-based asymmetric Schiff bases metal complexes. Applications of DAMN-based asymmetric Schiff bases are also discussed in this review.

  6. Chemistry and applications of organotin(IV) complexes of Schiff bases.

    PubMed

    Nath, Mala; Saini, Pramendra K

    2011-07-21

    Schiff bases are the most widely used versatile ligands, able to coordinate many elements and to stabilize them in various oxidation states. Recently, this class of compounds has been employed as models for biological systems, and in control of stereochemistry in six-coordinate transition metal complexes. Recently, the chemistry of organotin(IV) complexes of Schiff bases has also stemmed from their antitumour, antimicrobial, antinematicidal, anti-insecticidal and anti-inflammatory activities. Furthermore, organotin(IV) complexes of Schiff bases present a wide variety of interesting structural possibilities. Both aliphatic and aromatic Schiff bases in their neutral and deprotonated forms have been used to yield adducts and chelates with variable stoichiometry and different modes of coordination. This critical review (>155 references) focuses upon the chemistry and biological applications of organotin(IV) complexes of Schiff bases reported in the past 15 years. Thermal behavior of these complexes is also discussed. PMID:21494719

  7. Syntheses, Spectral Characterization, and Antimicrobial Studies on the Coordination Compounds of Metal Ions with Schiff Base Containing Both Aliphatic and Aromatic Hydrazide Moieties

    PubMed Central

    Kumar, Dinesh; Chadda, Silky; Sharma, Jyoti; Surain, Parveen

    2013-01-01

    An EtOH solution of 3-ketobutanehydrazide and salicylhydrazide on refluxing in equimolar ratio forms the corresponding Schiff base, LH3 (1). The latter reacts with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Zr(OH)2(IV), MoO2(VI), and UO2(VI) ions in equimolar ratio and forms the corresponding coordination compounds, [M(LH)(MeOH)3] (2, M = Mn, Co, Ni), [Cu(LH)]2 (3), [M?(LH)(MeOH)] (4, M? = Zn, Cd), [Zr(OH)2(LH)(MeOH)2] (5), [MoO2(LH)(MeOH)] (6), and [UO2(LH)(MeOH)] (7). The coordination compounds have been characterized on the basis of elemental analyses, molar conductance, spectral (IR, reflectance, 1H NMR, ESR) studies, and magnetic susceptibility measurements. They are nonelectrolytes in DMSO. The coordination compounds, except 3, are monomers in diphenyl. They are active against gram-positive bacteria (S. aureus, B. subtilis), gram-negative bacteria (E. coli, P. aeruginosa), and yeast (S. cerevisiae, C. albicans). 1 acts as a dibasic tridentate ONO donor ligand in 27 coordinating through its both enolic O and azomethine N atoms. The coordination compounds 2 and 3 are paramagnetic, while rest of the compounds are diamagnetic. A square-planar structure to 3, a tetrahedral structure to 4, an octahedral structure to 2, 6, and 7, and a pentagonal bipyramidal structure to 5 are proposed. PMID:24198736

  8. Mono-Schiff-base or di-Schiff-base? Synthesis, spectroscopic, X-ray structural and DFT study of a series of Schiff-bases derived from benzil dihydrazone

    NASA Astrophysics Data System (ADS)

    Tan, Xue-Jie; Hao, Xiu-Qi; Zhao, Qing-Zhe; Cheng, Shuang-Shuang; Xie, Wen-Long; Xing, Dian-Xiang; Liu, Yun; Song, Lai-Zhou

    2015-11-01

    A series of mono- and di-Schiff-bases based on Benzil Dihydrazone (BDH) were designed and synthesized to be set as the model compounds to explain which one should be the advanced product and which parameters will determine the end-product. As the first step of a series of investigations, this article presents the syntheses and characterization of five new Schiff-bases plus one preliminary reported Schiff-base, all derived from BDH. The compounds were characterized by single crystal (or conventional powder) X-ray diffractometry, elemental analysis, m.p., 1H NMR, 13C NMR, IR and UV-Vis. Structural features of the five new Schiff-bases are similar. For instance, all molecules are nonsymmetrical/symmetrical double helix with the torsion angle of two "half-parts" about 72-97. The Ph-Cdbnd N-Ndbnd C-Ph moiety all exists in planar and anti form, indicating significant conjugation. The crystal structures appear to be stabilized by ?-stacking between the aromatic rings, as well as by intermolecular hydrogen bonds and C-H ? stacking interactions. DFT calculations have been performed to explain the trend of the experimentally measured reaction yields. In the case of the studied systems by us, the type of Schiff-bases exhibits a clear dependence on the molar ratio of reactants if the products have similar stabilities. Otherwise the importance of reaction conditions will be weakened and the most stable product will be favored.

  9. Synthesis, crystal structure and complexing properties of calix[4]pyrrole 10?,20?-disubstituted Schiff bases and urea derivatives

    NASA Astrophysics Data System (ADS)

    Han, Ying; Sun, Juan-Juan; Wang, Gen-Liang; Yan, Chao-Guo

    2015-03-01

    10?,20?-di(4-aminophenyl)calix[4]pyrroles were synthesized from the acid catalyzed cyclization of dialkyldipyrromethanes with p-nitroacetophenone and sequential hydrogenation of nitro group, which in turn reacted with several aromatic aldehydes and pyridinecarboxaldehydes as well as isocyanates to give a series of calix[4]pyrrole 10?,20?-disubstituted Schiff base and urea derivatives. The crystal structures of the newly-formed calix[4]pyrrole Schiff bases were successfully determined by X-ray diffraction. The complexing property of calix[4]pyrrole Schiff bases for transition metal ions was also investigated with UV-Vis spectroscopy.

  10. Schiff bases: a short survey on an evergreen chemistry tool.

    PubMed

    Qin, Wenling; Long, Sha; Panunzio, Mauro; Biondi, Stefano

    2013-01-01

    The review reports a short biography of the Italian naturalized chemist Hugo Schiff and an outline on the synthesis and use of his most popular discovery: the imines, very well known and popular as Schiff Bases. Recent developments on their "metallo-imines" variants have been described. The applications of Schiff bases in organic synthesis as partner in Staudinger and hetero Diels-Alder reactions, as "privileged" ligands in the organometallic complexes and as biological active Schiff intermediates/targets have been reported as well. PMID:24108395

  11. Ruthenium(II) hydrazone Schiff base complexes: Synthesis, spectral study and catalytic applications

    NASA Astrophysics Data System (ADS)

    Manikandan, R.; Viswanathamurthi, P.; Muthukumar, M.

    2011-12-01

    Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B = PPh 3, AsPh 3 or Py; L = hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh 3) 2(B)] (where E = P or As; B = PPh 3, AsPh 3 or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, 1H, 13C and 31P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol.

  12. Anion recognition by simple chromogenic and chromo-fluorogenic salicylidene Schiff base or reduced-Schiff base receptors

    NASA Astrophysics Data System (ADS)

    Dalapati, Sasanka; Jana, Sankar; Guchhait, Nikhil

    2014-08-01

    This review contains extensive application of anion sensing ability of salicylidene type Schiff bases and their reduced forms having various substituents with respect to phenolic sbnd OH group. Some of these molecular systems behave as receptor for recognition or sensing of various anions in organic or aqueous-organic binary solvent mixture as well as in the solid supported test kits. Development of Schiff base or reduced Schiff base receptors for anion recognition event is commonly based on the theory of hydrogen bonding interaction or deprotonation of phenolic -OH group. The process of charge transfer (CT) or inhibition of excited proton transfer (ESIPT) or followed by photo-induced electron transfer (PET) lead to naked-eye color change, UV-vis spectral change, chemical shift in the NMR spectra and fluorescence spectral modifications. In this review we have tried to discuss about the anion sensing properties of Schiff base or reduced Schiff base receptors.

  13. Monodentate Schiff base ligands: their structural characterization, photoluminescence, anticancer, electrochemical and sensor properties.

    PubMed

    Kse, Muhammet; Ceyhan, Gkhan; Tmer, Mehmet; Demirta?, Ibrahim; Gnl, ?lyas; McKee, Vickie

    2015-02-25

    Two Schiff base compounds, N,N'-bis(2-methoxy phenylidene)-1,5-diamino naphthalene (L(1)) and N,N'-bis(3,4,5-trimethoxy phenylidene)-1,5-diamino naphthalene (L(2)) were synthesized and characterized by the analytical and spectroscopic methods. The electrochemical and photoluminescence properties of the Schiff bases were investigated in the different conditions. The compounds L(1) and L(2) show the reversible redox processes at some potentials. The sensor properties of the Schiff bases were examined and color changes were observed upon addition of the metal cations, such as Hg(II), Cu(II), Co(II) and Al(III). The Schiff base compounds show the bathochromic shift from 545 to 585 nm. The single crystals of the compounds (L(1)) and (L(2)) were obtained from the methanol solution and characterized structurally by the X-ray crystallography technique. The molecule L(2) is centrosymmetric whereas the L(1) has no crystallographically imposed molecular symmetry. However, the molecular structures for these compounds are quite similar, differing principally in the conformation about methoxy groups and the dihedral angle between the two aromatic rings and diamine naphthalene. PMID:25238187

  14. Monodentate Schiff base ligands: Their structural characterization, photoluminescence, anticancer, electrochemical and sensor properties

    NASA Astrophysics Data System (ADS)

    Köse, Muhammet; Ceyhan, Gökhan; Tümer, Mehmet; Demirtaş, İbrahim; Gönül, İlyas; McKee, Vickie

    2015-02-01

    Two Schiff base compounds, N,N‧-bis(2-methoxy phenylidene)-1,5-diamino naphthalene (L1) and N,N‧-bis(3,4,5-trimethoxy phenylidene)-1,5-diamino naphthalene (L2) were synthesized and characterized by the analytical and spectroscopic methods. The electrochemical and photoluminescence properties of the Schiff bases were investigated in the different conditions. The compounds L1 and L2 show the reversible redox processes at some potentials. The sensor properties of the Schiff bases were examined and color changes were observed upon addition of the metal cations, such as Hg(II), Cu(II), Co(II) and Al(III). The Schiff base compounds show the bathochromic shift from 545 to 585 nm. The single crystals of the compounds (L1) and (L2) were obtained from the methanol solution and characterized structurally by the X-ray crystallography technique. The molecule L2 is centrosymmetric whereas the L1 has no crystallographically imposed molecular symmetry. However, the molecular structures for these compounds are quite similar, differing principally in the conformation about methoxy groups and the dihedral angle between the two aromatic rings and diamine naphthalene.

  15. Mechanism of base-catalyzed Schiff base deprotonation in halorhodopsin

    SciTech Connect

    Lanyi, J.K.

    1986-10-21

    It has been shown earlier that the deprotonation of the Schiff base of illuminated halorhodopsin proceeds with a much lower pK/sub a/ than that of the unilluminated pigment and the reversible protonation change is catalyzed by azide and cyanate. The authors have studied the kinetics of the proton-transfer events with flash spectroscopy and compared a variety of anionic bases with different pK/sub a/ with regard to the apparent binding constants and the catalytic activities. The results suggest a general base catalysis mechanism in which the anionic bases bind with apparently low affinity to halorhodopsin, although with some degree of size- and/or shape-dependent specificity. The locus of the catalysis is accessible from the cytoplasmic side of the membrane and is not at site I, where various anions bind and shift the pK/sub a/ of the deprotonation. Neither is it at site II, where a few specific anions (like chloride) bind to the all-trans pigment. It may be concluded that while the all-trans pigment loses its Schiff base proton very rapidly at its pK/sub a/, there is a kinetic barrier to this deprotonation in the 13-cis photointermediate that can be partially overcome by the reversible protonation of an extrinsic anionic base, which shuttles protons between the interior of the protein and the aqueous medium. The need for an extrinsic proton acceptor for efficient deprotonation of the Schiff base of halorhodopsin is one of the main differences between this pigment and the analogous retinal protein, bacteriorhodopsin.

  16. Synthesis and Antimicrobial activity of some new Schiff bases

    NASA Astrophysics Data System (ADS)

    G, Karamunge K.; B, Vibhute Y.

    2013-04-01

    New Schiff bases derived from 4iodoaniline, 4-chloroniline, p- toluidine and halogenohydroxy substituted acetophenone have been synthesized. All the compounds have been characterized by IR, H1NMR and mass spectral, halogen, nitrogen analysis. The synthesized compounds have been screened for antimicrobial activity.

  17. Synthesis of novel bisindolylmethane Schiff bases and their antibacterial activity.

    PubMed

    Imran, Syahrul; Taha, Muhammad; Ismail, Nor Hadiani; Khan, Khalid Mohammed; Naz, Farzana; Hussain, Memona; Tauseef, Saima

    2014-01-01

    In an effort to develop new antibacterial drugs, some novel bisindolylmethane derivatives containing Schiff base moieties were prepared and screened for their antibacterial activity. The synthesis of the bisindolylmethane Schiff base derivatives 3-26 was carried out in three steps. First, the nitro group of 3,3'-((4-nitrophenyl)-methylene)bis(1H-indole) (1) was reduced to give the amino substituted bisindolylmethane 2 without affecting the unsaturation of the bisindolylmethane moiety using nickel boride in situ generated. Reduction of compound 1 using various catalysts showed that combination of sodium borohydride and nickel acetate provides the highest yield for compound 2. Bisindolylmethane Schiff base derivatives were synthesized by coupling various benzaldehydes with amino substituted bisindolylmethane 2. All synthesized compounds were characterized by various spectroscopic methods. The bisindolylmethane Schiff base derivatives were evaluated against selected Gram-positive and Gram-negative bacterial strains. Derivatives having halogen and nitro substituent display weak to moderate antibacterial activity against Salmonella typhi, S. paratyphi A and S. paratyphi B. PMID:25102118

  18. Synthesis and spectroscopic properties of novel asymmetric Schiff bases

    NASA Astrophysics Data System (ADS)

    Gngr, zlem; Grkan, Perihan

    2010-09-01

    Three novel diimine Schiff bases including two asymmetric imines (2-OH)R-CH dbnd N-C 6H 4-CH dbnd N-R'(2-OH) type [where R = R' = phenyl for H 2L 1; R = naphthyl, R' = phenyl for H 2L 2 and R = R' = naphthyl for H 2L 3] have been synthesized with a new two step method. For this purpose, the starting Schiff bases 4-nitrobenzylidene-2-hydroxyaniline (SB 1-NO 2) and 4-nitrobenzylidene-2-hydroxy-3-naphthylamine (SB 2-NO 2) have been synthesized, previously. Nitro groups of them have been reduced into their amino derivatives (SB 1-NH 2 and SB 2-NH 2) with sodium dithionite as selective reductant and the other imino groups have been formed by adding salicylaldehyde or 2-hydroxy-1-naphthaldehyde to the same solutions. The structures of the diimine Schiff bases were confirmed by elemental analyses, ESI-MS, FT-IR, 1H NMR and 13C NMR spectroscopy. The phenol-imine and keto-amine tautomerism of the Schiff bases were investigated by FT-IR, 1H NMR, 13C NMR techniques and UV-vis spectra in different solvents (DMSO, methanol, chloroform, toluene and cyclohexane). The effects of acidic and basic media on the tautomeric equilibria were discussed.

  19. Synthesis and spectroscopic properties of novel asymmetric Schiff bases.

    PubMed

    Gngr, Ozlem; Grkan, Perihan

    2010-09-15

    Three novel diimine Schiff bases including two asymmetric imines (2-OH)R-CHN-C(6)H(4)-CHN-R'(2-OH) type [where R=R'=phenyl for H(2)L(1); R=naphthyl, R'=phenyl for H(2)L(2) and R=R'=naphthyl for H(2)L(3)] have been synthesized with a new two step method. For this purpose, the starting Schiff bases 4-nitrobenzylidene-2-hydroxyaniline (SB(1)-NO(2)) and 4-nitrobenzylidene-2-hydroxy-3-naphthylamine (SB(2)-NO(2)) have been synthesized, previously. Nitro groups of them have been reduced into their amino derivatives (SB(1)-NH(2) and SB(2)-NH(2)) with sodium dithionite as selective reductant and the other imino groups have been formed by adding salicylaldehyde or 2-hydroxy-1-naphthaldehyde to the same solutions. The structures of the diimine Schiff bases were confirmed by elemental analyses, ESI-MS, FT-IR, (1)H NMR and (13)C NMR spectroscopy. The phenol-imine and keto-amine tautomerism of the Schiff bases were investigated by FT-IR, (1)H NMR, (13)C NMR techniques and UV-vis spectra in different solvents (DMSO, methanol, chloroform, toluene and cyclohexane). The effects of acidic and basic media on the tautomeric equilibria were discussed. PMID:20541456

  20. Synthesis and Characterization of Metal Complexes with Schiff Base Ligands

    ERIC Educational Resources Information Center

    Wilkinson, Shane M.; Sheedy, Timothy M.; New, Elizabeth J.

    2016-01-01

    In order for undergraduate laboratory experiments to reflect modern research practice, it is essential that they include a range of elements, and that synthetic tasks are accompanied by characterization and analysis. This intermediate general chemistry laboratory exercise runs over 2 weeks, and involves the preparation of a Schiff base ligand and…

  1. Synthesis and Characterization of Metal Complexes with Schiff Base Ligands

    ERIC Educational Resources Information Center

    Wilkinson, Shane M.; Sheedy, Timothy M.; New, Elizabeth J.

    2016-01-01

    In order for undergraduate laboratory experiments to reflect modern research practice, it is essential that they include a range of elements, and that synthetic tasks are accompanied by characterization and analysis. This intermediate general chemistry laboratory exercise runs over 2 weeks, and involves the preparation of a Schiff base ligand and

  2. Construction of Novel Zn-Ni Trinuclear Schiff Base and a Ni2+ Chemosensor

    SciTech Connect

    Li, Guo-Bi; Fang, Hua-Cai; Cai, Yue-Peng; Zhou, Zheng-Yuan; Thallapally, Praveen K.; Tian, Jian

    2010-07-14

    The novel Schiff base Zn-Ni trinuclear complex (Zn[Ni(sy- L2)]2(SCN)2, where sy-H2L2 = H2acacen = bis(acetylacetone)ethylenediamine), which is the first trinuclear compound based on symmetric acacen-base Schiff base ligand, was constructed through Ni2+-selective assembly of chemosensor Schiff base zinc compound Zn[(sy-H2L2)(SCN)]2?(CH3CN)2.

  3. Synthesis and Degradation of Schiff Bases Containing Heterocyclic Pharmacophore

    PubMed Central

    Lede?i, Ionu?; Alexa, Anda; Bercean, Vasile; Vlase, Gabriela; Vlase, Titus; ?uta, Lenu?a-Maria; Fulia?, Adriana

    2015-01-01

    This paper reports on the synthesis and characterization of two Schiff bases bearing 1,2,4-triazolic moieties, namely 4H-4-(2-hydroxy-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole and 4H-4-(4-nitro-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole using thin layer chromatography, melting interval, elemental analysis, spectroscopy and thermal stability studies. PMID:25590299

  4. Oxidative peptide /and amide/ formation from Schiff base complexes

    NASA Technical Reports Server (NTRS)

    Strehler, B. L.; Li, M. P.; Martin, K.; Fliss, H.; Schmid, P.

    1982-01-01

    One hypothesis of the origin of pre-modern forms of life is that the original replicating molecules were specific polypeptides which acted as templates for the assembly of poly-Schiff bases complementary to the template, and that these polymers were then oxidized to peptide linkages, probably by photo-produced oxidants. A double cycle of such anti-parallel complementary replication would yield the original peptide polymer. If this model were valid, the Schiff base between an N-acyl alpha mino aldehyde and an amino acid should yield a dipeptide in aqueous solution in the presence of an appropriate oxidant. In the present study it is shown that the substituted dipeptide, N-acetyl-tyrosyl-tyrosine, is produced in high yield in aqueous solution at pH 9 through the action of H2O2 on the Schiff-base complex between N-acetyl-tyrosinal and tyrosine and that a great variety of N-acyl amino acids are formed from amino acids and aliphatic aldehydes under similar conditions.

  5. Mononuclear and tetranuclear Fe(III) complexes with two different types of N, O donor Schiff base ligands

    NASA Astrophysics Data System (ADS)

    Sutradhar, Manas; Roy Barman, Tannistha; Drew, Michael G. B.; Rentschler, Eva

    2013-06-01

    A mononuclear Fe(III) complex of a tetradentate N2O2 donor Schiff base ligand derived from 3-ethoxysalicaldehyde and ethylenediamine has been reported. In addition two tetranuclear Fe(III) complexes with discrete Fe4III(μ4-O) cores have been synthesized and characterized using two Schiff base ligands (H2L1-2) derived from two different aromatic acid hydrazides and diacetyl monoxime. The mononuclear Fe(III) and one of the tetranuclear Fe(III) complexes have been structurally characterized by single-crystal X-ray crystallography. The mononuclear complex has a highly distorted octahedral geometry. The tetranuclear Fe(III) complexes are found to be rare examples with discrete neutral alkoxido-oxido clusters with Fe4III(μ4-O) cores.

  6. Synthesis of cytotoxic and antioxidant Schiff's base analogs of aloin.

    PubMed

    Kumar, S; Matharasi, D Priya; Gopi, Sreeraj; Sivakumar, S; Narasimhan, S

    2010-05-01

    Aloin (10-glucopyranosyl-1,8-dihydroxy-3-hydroxymethyl-9(10H)-anthracenone), a bioactive compound in Aloe vera, although known to have an anticancer effect, has not been used in current drug research. Optimization of the lead structure could enhance the utility of this compound. Hence, aloin was modified using natural amino acids to produce Schiff's base, a potential pharmacophore, and its corresponding aglycones. The synthetic derivatives exhibited significant enhancement in their efficacy toward antioxidant (DPPH radical scavenging) and cytotoxic activities than those of the parent compound, aloin showing promise for application in cancer treatment. PMID:20496193

  7. Gas phase tautomerism of tautomeric azo naphthols and related Schiff bases studied by mass spectrometry

    NASA Astrophysics Data System (ADS)

    Nedeltcheva, Daniela; Damyanova, Boryana; Popov, Simeon

    2005-07-01

    Mass spectra of several azonaphthols and related Schiff bases containing intramolecular hydrogen bonding (IHB) are interpreted in respect of their keto-enol tautomerism. It is shown that in gas phase the enol-like tautomer strongly predominates. In the azodyes the existing IHB is very weak, while in the corresponding Schiff bases it is strong enough and determines the fragmentation pathway.

  8. The pKa of the protonated Schiff bases of gecko cone and octopus visual pigments.

    PubMed Central

    Liang, J; Steinberg, G; Livnah, N; Sheves, M; Ebrey, T G; Tsuda, M

    1994-01-01

    A visual pigment is composed of retinal bound to its apoprotein by a protonated Schiff base linkage. Light isomerizes the chromophore and eventually causes the deprotonation of this Schiff base linkage at the meta II stage of the bleaching cycle. The meta II intermediate of the visual pigment is the active form of the pigment that binds to and activates the G protein transducin, starting the visual cascade. The deprotonation of the Schiff base is mandatory for the formation of meta II intermediate. We studied the proton binding affinity, pKa, of the Schiff base of both octopus rhodopsin and the gecko cone pigment P521 by spectral titration. Several fluorinated retinal analogs have strong electron withdrawing character around the Schiff base region and lower the Schiff base pKa in model compounds. We regenerated octopus and gecko visual pigments with these fluorinated and other retinal analogs. Experiments on these artificial pigments showed that the spectral changes seen upon raising the pH indeed reflected the pKa of the Schiff base and not the denaturation of the pigment or the deprotonation of some other group in the pigment. The Schiff base pKa is 10.4 for octopus rhodopsin and 9.9 for the gecko cone pigment. We also showed that although the removal of Cl- ions causes considerable blue-shift in the gecko cone pigment P521, it affects the Schiff base pKa very little, indicating that the lambda max of visual pigment and its Schiff base pKa are not tightly coupled. PMID:7948697

  9. Chelating ability and biological activity of hesperetin Schiff base.

    PubMed

    Lodyga-Chruscinska, Elzbieta; Symonowicz, Marzena; Sykula, Anna; Bujacz, Anna; Garribba, Eugenio; Rowinska-Zyrek, Magdalena; Oldziej, Stanislaw; Klewicka, Elzbieta; Janicka, Magdalena; Krolewska, Karolina; Cieslak, Marcin; Brodowska, Katarzyna; Chruscinski, Longin

    2015-02-01

    Hydrazone hesperetin Schiff base (HHSB) - N-[()-[5,7-dihydroxy-2-(3-hydroxy-4-methoxy-phenyl)chroman-4-ylidene]amino]benzamide has been synthesized and its crystal structure was determined. This compound was used for the formation of Cu(II) complexes in solid state and in solution which were characterized using different spectroscopic methods. The analyses of potentiometric titration curves revealed that monomeric and dimeric complexes of Cu(II) are formed above pH7. The ESI-MS (electrospray ionization-mass spectrometry) spectra confirmed their formation. The EPR and UV-visible spectra evidenced the involvement of oxygen and nitrogen atoms in Cu(II) coordination. Hydrazone hesperetin Schiff base can show keto-enol tautomerism and coordinate Cu(II) in the keto (O(-), N, Oket) and in the enolate form (O(-), N, O(-)enol). The semi-empirical molecular orbital method PM6 and DFT (density functional theory) calculations have revealed that the more stable form of the dimeric complex is that one in which the ligand is present in the enol form. The CuHHSB complex has shown high efficiency in the cleavage of plasmid DNA in aqueous solution, indicating its potential as chemical nuclease. Studies on DNA interactions, antimicrobial and cytotoxic activities have been undertaken to gain more information on the biological significance of HHSB and copper(II)-HHSB chelate species. PMID:25486205

  10. Novel dipodal Schiff base compounds: Synthesis, characterization and spectroscopic studies

    NASA Astrophysics Data System (ADS)

    Obali, Aslihan Yilmaz; Ucan, Halil Ismet

    2015-02-01

    Two novel dipodal Schiff base compounds 1,2-benzyloxy-bis-[2-(benzylideneamino)phenol, L1 and 1,2-benzyloxy-bis[3-(benzylideneamino)pyridine], L2 were synthesized. Their sensing actions were confirmed by UV-Vis absorbance and emission spectroscopic studies in presence of Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II) in methanol medium (1 × 10-4 M). It was found that the dipodal compounds can selectively bind to Cu(II) and Pb(II) metal ions with a significant change in its emission and absorption spectra, while the addition of other metal ions (Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Sn(II), Cd(II) and Pb(II)) produces insignificant or minor changes. The host-guest complexes formed were determined by Job's plot method. As a chemosensor, L1 and L2 dipodal Schiff base compounds shows a specific selectivity towards Cu(II) and Pb(II) ions in according to all spectroscopic data.

  11. Interaction of Schiff base ligand with tin dioxide nanoparticles: optical studies.

    PubMed

    Rani, J Suvetha; Ramakrishnan, V

    2013-10-01

    Interaction between 1,4 Bis ((2-Methyl) thio) Phenylamino methyl benzene (BMTPMB) Schiff base with tin dioxide nanoparticles (SnO2 NPs) of various concentrations in methanol have been studied using UV-Visible and Fluorescence spectroscopic techniques. The low value of Stern-Volmer quenching constant and non-linear plot of Benesi-Hildebrand equation suggests the less affinity of SnO2 NPs towards the adsorption of BMTPMB Schiff base. The Scott equation has been employed to determine molar absorptivity of the Schiff base-NPs system. PMID:23770505

  12. Interaction of Schiff base ligand with tin dioxide nanoparticles: Optical studies

    NASA Astrophysics Data System (ADS)

    Suvetha Rani, J.; Ramakrishnan, V.

    2013-10-01

    Interaction between 1,4 Bis ((2-Methyl) thio) Phenylamino methyl benzene (BMTPMB) Schiff base with tin dioxide nanoparticles (SnO2 NPs) of various concentrations in methanol have been studied using UV-Visible and Fluorescence spectroscopic techniques. The low value of Stern-Volmer quenching constant and non-linear plot of Benesi-Hildebrand equation suggests the less affinity of SnO2 NPs towards the adsorption of BMTPMB Schiff base. The Scott equation has been employed to determine molar absorptivity of the Schiff base-NPs system.

  13. Synthesis, characterization and antibacterial activity of biodegradable films prepared from Schiff bases of zein.

    PubMed

    Soliman, E A; Khalil, A A; Deraz, S F; El-Fawal, G; Elrahman, S Abd

    2014-10-01

    Pure zein is known to be very hydrophobic, but is still inappropriate for coating and film applications because of their brittle nature. In an attempt to improve the flexibility and the antimicrobial activity of these coatings and films, Chemical modification of zein through forming Schiff bases with different phenolic aldhydes was tried. Influence of this modifications on mechanical, topographical, wetting properties and antimicrobial activity of zein films were evaluated. The chemical structure of the Schiff bases films were characterized by ATR-FTIR spectroscopy. The results indicate an improvement in mechanical properties with chemically modification of zein to form Schiff bases leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with slight influence on tensile strength. Plasticized zein films have similar initial contact angle (∼40°). An increase in reaction temperature and time increases film's affinity towards water. As shown by contact angle measurements, a noticeable relation was found between film composition and the hydrophilicity. Surface topography also varied by forming Schiff bases, becoming rougher than zein-based films. The antibacterial activities of zein and Schiff bases of zein-based films were investigated against gram-positive bacteria (Listeria innocua, Listeria monocytogenes, Bacillus cereus and Clostridium sporogenes) and gram-negative bacteria (Escherichia coli, Yersinia enterocolitica and Salmonella enterica). It was found that the antibacterial activity of the Schiff bases-based films was more effective than that of zein-based films. PMID:25328181

  14. Reversible Formation and Transmetalation of Schiff-Base Complexes in Subcomponent Self-Assembly Reactions.

    PubMed

    Lewing, Dennis; Koppetz, Hannah; Hahn, F Ekkehardt

    2015-08-01

    Dinuclear complexes [Zn2(NS,NS)2] 3 and [Ni2(NS,NS)2] 6 bearing Schiff-base ligands featuring two NS donor groups were obtained in subcomponent self-assembly reactions using nickel or zinc as template metals. Several transmetalation reactions starting from 3 or 6 yielded the complexes [Pd2(NS,NS)2] 4 and [Co2(NS,NS)2] 5, and their molecular structures were determined by X-ray diffraction. Starting from the mononuclear complex [Ni(NS/NOH)2] 9 featuring a coordinated NS Schiff base and a free NOH Schiff base, completely reversible thermodynamically controlled imine bond formation was observed leading to complex [Ni2(NS,NS)2] 6 and the free Schiff -base ligand NOH,NOH 10. PMID:26161894

  15. The effect of some Schiff bases on the corrosion of aluminum in hydrochloric acid solution

    NASA Astrophysics Data System (ADS)

    Ashassi-Sorkhabi, H.; Shabani, B.; Aligholipour, B.; Seifzadeh, D.

    2006-04-01

    The inhibition effect of Schiff bases benzylidene-(2-methoxy-phenyl)-amine (A), (2-methoxy-phenyl)-(4-methyl-benzylidene)-amine (B), (4-chloro-benzylidene)-(2-methoxy-phenyl)-amine (C) and (4-nitro-bezylidene)-(2-methoxy-phenyl)-amine (D) on the corrosion of aluminum in 1 M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. It has been found that all the studied Schiff bases are excellent inhibitors. Maximum inhibition was obtained for 0.01 M Schiff base A. Results show that the inhibition efficiency increases with decreasing in temperature and increasing in concentration of Schiff base. Polarization curves reveal that the used inhibitors are mixed type inhibitors. The surface adsorption of the Schiff bases leads to a decrease of double layer capacitance as well as an increase of polarization resistance. The inhibitor performance depends strongly on the type of function groups substituted on benzene ring. The adsorption of used compounds on the aluminum surface obeys a Langmuir isotherm and has a physical mechanism. Thermodynamic parameters for both dissolution and adsorption processes were determined. The quantum chemical study of the corrosion inhibition efficiency of the Schiff bases on Al in molar HCl was carried out.

  16. Synthesis, characterization and antimicrobial studies of Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Zafar, Hina; Ahmad, Anis; Khan, Asad U.; Khan, Tahir Ali

    2015-10-01

    The Schiff base complexes, MLCl2 [M = Fe(II), Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by the template reaction of respective metal ions with 2-acetylpyrrole and 1,3-diaminopropane in 1:2:1 M ratio. The complexes have been characterized by elemental analyses, ESI - mass, NMR (1H and 13C), IR, XRD, electronic and EPR spectral studies, magnetic susceptibility and molar conductance measurements. These studies show that all the complexes have octahedral arrangement around the metal ions. The molar conductance measurements of all the complexes in DMSO indicate their non-electrolytic nature. The complexes were screened for their antibacterial activity in vitro against Gram-positive (Streptococcus pyogenes) and Gram-negative (Klebsiella pneumoniae) bacteria. Among the metal complexes studied the copper complex [CuLCl2], showed highest antibacterial activity nearly equal to standard drug ciprofloxacin. Other complexes also showed considerable antibacterial activity. The relative order of activity against S. Pyogenes is as Cu(II) > Zn(II) > Co(II) = Fe(II) > Ni(II) and with K. Pneumonia is as Cu(II) > Co(II) > Zn(II) > Fe(II) > Ni(II).

  17. A new copper(II) Schiff base complex containing asymmetrical tetradentate N2O2 Schiff base ligand: Synthesis, characterization, crystal structure and DFT study

    NASA Astrophysics Data System (ADS)

    Grivani, Gholamhossein; Baghan, Sara Husseinzadeh; Vakili, Mohammad; Khalaji, Aliakbar Dehno; Tahmasebi, Vida; Eigner, Vclav; Duek, Michal

    2015-02-01

    A new copper (II) Schiff base complex, CuL1, was prepared from the reaction of asymmetrical Schiff base ligand of L1 and Cu(OAC)2 (L1 = salicylidene imino-ethylimino-pentan-2-one). The Schiff base ligand, L1, and its copper (II) complex, CuL1, have been characterized by elemental analysis (CHN) and FT-IR and UV-vis spectroscopy. In addition, 1H NMR was employed for characterization of the ligand. Thermogrametric analysis of the CuL1 reveals its thermal stability and its decomposition pattern shows that it is finally decomposed to the copper oxide (CuO). The crystal structure of CuL1 was determined by the single crystal X-ray analysis. The CuL1 complex crystallizes in the monoclinic system, with space group P21/n and distorted square planar coordination around the metal ion. The Schiff base ligand of L1 acts as a chelating ligand and coordinates via two nitrogen and two oxygen atoms to the copper (II) ion with C1 symmetry. The structure of the CuL1 complex was also studied theoretically at different levels of DFT and basis sets. According to calculated results the Csbnd O bond length of the salicylate fragment is slightly higher than that in the acetylacetonate fragment of ligand, which could be interpreted by resonance increasing between phenyl and chelated rings in ligand in relative to the acetylacetonate fragment.

  18. Synthesis, potentiometric and antimicrobial studies on metal complexes of isoxazole Schiff bases

    NASA Astrophysics Data System (ADS)

    Prashanthi, Y.; Kiranmai, K.; Subhashini, N. J. P.; Shivaraj

    2008-06-01

    The metal complexes of Cu(II), Ni(II) and Co(II) with Schiff bases of 3-(2-hydroxy-3-ethoxybenzylideneamino)-5-methyl isoxazole [HEBMI] and 3-(2-hydroxy-5-nitrobenzylidene amino)-5-methyl isoxazole [HNBMI] which were obtained by the condensation of 3-amino-5-methyl isoxazole with substituted salicylaldehydes have been synthesized. Schiff bases and their complexes have been characterized on the basis of elemental analysis, magnetic moments, molar conductivity, thermal analysis and spectral (IR, UV, NMR and Mass) studies. The spectral data show that these ligands act in a monovalent bidentate fashion, co-ordinating through phenolic oxygen and azomethine nitrogen atoms. Chelates of Co(II), Ni(II) appear to be octahedral and Cu(II) appears to be distorted octahedral. To investigate the relationship between formation constants of binary complexes and antimicrobial activity, the dissociation constants of Schiff bases and stability constants of their binary metal complexes have been determined potentiometrically in aqueous solution at 30 1 C and at 0.1 M KNO 3 ionic strength and discussed. Antimicrobial activities of the Schiff bases and their complexes were screened. The structure-activity correlation in Schiff bases and their metal(II) complexes are discussed, based on the effect of their stability constants. It is observed that the activity enhances upon complexation and the order of activity is in accordance with stability order of metal ions.

  19. Synthesis of Some Novel Heterocyclic and Schiff Base Derivatives as Antimicrobial Agents.

    PubMed

    Azab, Mohamed E; Rizk, Sameh A; Amr, Abd El-Galil E

    2015-01-01

    Treatment of 2,3-diaryloxirane-2,3-dicarbonitriles 1a-c with different nitrogen nucleophiles, e.g., hydrazine, methyl hydrazine, phenyl hydrazine, hydroxylamine, thiosemicarbazide, and/or 2-amino-5-phenyl-1,3,4-thiadiazole, afforded pyrazole, isoxazole, pyrrolotriazine, imidazolothiadiazole derivatives 2-5, respectively. Reacting pyrazoles 2a-c with aromatic aldehydes and/or methyl glycinate produced Schiff's bases 7a-d and pyrazolo[3,4-b]-pyrazinone derivative 8, respectively. Treating 7 with ammonium acetate and/or hydrazine hydrate, furnished the imidazolopyrazole and pyrazolotriazine derivatives 9 and 10, respectively. Reaction of 8 with chloroacetic acid and/or diethyl malonate gave tricyclic compound 11 and triketone 12, respectively. On the other hand, compound 1 was reacted with active methylene precursors, e.g., acetylacetone and/or cyclopentanone producing adducts 14a,b which upon fusion with ammonium acetate furnished the 3-pyridone derivatives 15a,b, respectively. Some of newly synthesized compounds were screened for activity against bacterial and fungal strains and most of the newly synthesized compounds showed high antimicrobial activities. The structures of the new compounds were elucidated using IR, H-NMR, (13)C-NMR and mass spectroscopy. PMID:26457697

  20. Large and negative magnetic anisotropy in pentacoordinate mononuclear Ni(ii) Schiff base complexes.

    PubMed

    Nemec, Ivan; Herchel, Radovan; Svoboda, Ingrid; Bo?a, Roman; Trvn?ek, Zden?k

    2015-05-28

    A series of pentacoordinate Ni(ii) complexes of the general formula [Ni(L5)] () with various pentadentate Schiff base ligands H2L5 (originating in a condensation of aromatic ortho-hydroxy-aldehydes and aliphatic triamines) was synthesized and characterized by X-ray structure analysis and magnetometry. The alternations of substituents on the H2L parent ligand resulted in the complexes with the geometry varying between the square-pyramid and trigonal-bipyramid. In the compounds whose chromophore geometry is closer to a trigonal-bipyramid, a large and negative uniaxial anisotropy (D = -64 cm(-1)) was identified. Moreover, the simple linear expression for the axial zero-field splitting (ZFS) parameter, D/cm(-1) = 32.7(4.8) - 151(10)?, was proposed, where ? (in degrees) stands for the Addison parameter. The results of magnetic analysis were also supported by ab initio CASSCF/NEVPT2 calculations of the ZFS splitting parameters D and E, and g tensors. Despite large and negative D-values of the reported compounds, slow relaxation of magnetization was not observed either in zero or non-zero static magnetic field, thus no single-molecule magnetic behaviour was detected. PMID:25919125

  1. An extending evidence of molecular conformation on spectroscopic properties of symmetrical bis-Schiff bases

    NASA Astrophysics Data System (ADS)

    Fang, Zhengjun; Cao, Chenzhong; Chen, Jianfang; Deng, Xingchen

    2014-04-01

    The relationship between the molecular conformation and spectroscopic properties of symmetrical bis-Schiff bases, was explored experimentally. The synthesis, crystal structures, and spectroscopic behaviors of symmetrical bis-Schiff bases derived from 1,4-Phthalaldehyde, p-Ysbnd C6H4Ndbnd CHC6H4CHdbnd NC6H4sbnd p-Y (Y = OMe, Me, H, Cl, or F) were reported. The results show when the effect of distance between X or Y and the imine carbon was considered, a good correlation between the ?max or ?C(Cdbnd N) of symmetrical bis-Schiff bases and the substituent parameters was obtained. The correlation results indicate that for both symmetrical bis-Schiff bases derived from 1,4-Phenylenediamine and 1,4-Phthalaldehyde, the UV absorption spectrum is dependent on the substituent at the aniline ring and the dihedral angle ?, and the term sin(?) is suitable to modify the substituent effects on the ?max. However, experimental investigations indicate that the dihedral angle ? has a limited effect on the values of ?C(Cdbnd N). This study provides an extending evidence of molecular conformation effects on spectroscopic properties of symmetrical bis-Schiff bases.

  2. Internal Proton Transfer in the External Pyridoxal 5?-Phosphate Schiff Base in Dopa Decarboxylase

    PubMed Central

    Lin, Yen-lin; Gao, Jiali

    2010-01-01

    Combined quantum mechanical and molecular mechanical (QM/MM) simulations of dopa decarboxylase have been carried out to elucidate the factors that contribute to the tautomeric equilibrium of the intramolecular proton transfer in the external PLPL-dopa Schiff base. The presence of a carboxylate anion on the ?-carbon of the Schiff base stabilizes the zwitterions and shifts the equilibrium in favor of the oxoenamine tautomer (protonated Schiff base). Moreover, protonation of the PLP pyridine nitrogen further drives the equilibrium toward the oxoenamine direction. On the other hand, solvent effects favor the hydroxyimine configuration, although the equilibrium favors the oxoenamine isomer with a methyl group as the substituent on the imino nitrogen. In dopa decarboxylase, the hydroxyimine form of the PLP(H+)L-dopa Schiff base is predicted to be the major isomer with a relative free energy of ?1.3 kcal/mol over that of the oxoenamine isomer. Both Asp271 and Lys303 stabilize the hydroxyimine configuration through hydrogen-bonding interactions with the pyridine nitrogen of the PLP and the imino nitrogen of the Schiff base, respectively. Interestingly, Thr246 plays a double role in the intramolecular proton transfer process, in which it initially donates a hydrogen bond to the phenolate oxygen in the oxoenamine configuration and then switches to a hydrogen bond acceptor from the phenolic hydroxyl group in the hydroxyimine tautomer. PMID:19938875

  3. Mononuclear Ru(III) Schiff base complexes: Synthesis, spectral, redox, catalytic and biological activity studies

    NASA Astrophysics Data System (ADS)

    Priya, N. Padma; Arunachalam, S.; Manimaran, A.; Muthupriya, D.; Jayabalakrishnan, C.

    2009-04-01

    An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh 3)(L)] (where, X = Cl/Br; E = As/P; L = dianion of the Schiff bases derived from acetoacetanilide with o-phenylenediamine and salicylaldehyde/ o-hydroxyacetophenone/ o-vanillin/2-hydroxy-1-naphthaldehyde) have been synthesized from the reactions of equimolar reactions of [RuX 3(EPh 3) 3] and Schiff bases in benzene. The new Ru(III) Schiff base complexes have been characterized by elemental analyses, FT-IR, electronic, 1H NMR and 13C NMR spectra, EPR spectral studies, powder X-ray diffraction (XRD) and electrochemical studies. The new complexes were found to be effective catalysts for aryl-aryl coupling and the oxidation of alcohols into their corresponding carbonyl compounds, respectively, using molecular oxygen atmosphere at ambient temperature. Further, the new Ru(III) Schiff base complexes were screened for their antibacterial activity against Pseudomonas aeruginosa, Vibrio cholera, Salomonella typhi and Staphylococcus aureaus.

  4. Ferrocene-Based Tetradentate Schiff Bases as Supporting Ligands in Uranium Chemistry.

    PubMed

    Camp, Clment; Chatelain, Lucile; Mougel, Victor; Pcaut, Jacques; Mazzanti, Marinella

    2015-06-15

    Uranyl(VI), uranyl(V), and uranium(IV) complexes supported by ferrocene-based tetradentate Schiff-base ligands were synthesized, and their solid-state and solution structures were determined. The redox properties of all complexes were investigated by cyclic voltammetry. The bulky salfen-(t)Bu2 allows the preparation of a stable uranyl(V) complex, while a stable U(IV) bis-ligand complex is obtained from the salt metathesis reaction between [UI4(OEt2)2] and K2salfen. The reduction of the [U(salfen)2] complex leads to an unprecedented intramolecular reductive coupling of the Schiff-base ligand resulting in a C-C bond between the two ferrocene-bound imino groups. PMID:26010406

  5. Synthesis and characterization of higher amino acid Schiff bases, as monosodium salts and neutral forms. Investigation of the intramolecular hydrogen bonding in all Schiff bases, antibacterial and antifungal activities of neutral forms

    NASA Astrophysics Data System (ADS)

    Güngör, Özlem; Gürkan, Perihan

    2014-09-01

    Schiff bases derived from 5-nitro-salicylaldehyde and 4-aminobutyric acid, 5-aminopentanoic acid and 6-aminohexanoic acid were synthesized both as monosodium salts (1a-3a) and neutral forms (1b-3b). The monosodium-Schiff bases were characterized by elemental analysis, 1H/13C NMR, IR, powder XRD, UV-vis spectra and conductivity measurements. The neutral-Schiff bases were characterized by elemental analysis, 1H/13C NMR, 2D NMR (HMQC), mass, IR, powder XRD, UV-vis spectra and conductivity measurements. The intramolecular hydrogen bonding and related tautomeric equilibria in all the Schiff bases were studied by UV-vis and 1H NMR spectra in solution. Additionally, the neutral-Schiff bases were screened against Staphylococcus aureus-EB18, S. aureus-ATCC 25923, Escherichia coli-ATCC 11230, Candida albicans-M3 and C. albicans-ATCC 16231.

  6. The exceptionally rich coordination chemistry generated by Schiff-base ligands derived from o-vanillin.

    PubMed

    Andruh, Marius

    2015-10-14

    Ortho-vanillin became very popular in coordination chemistry because of its Schiff bases, which generate a rich variety of complexes, ranging from oligonuclear species to coordination polymers. Some of these organic molecules are particularly useful in metallosupramolecular chemistry for assembling homo- and heterometallic helicates. The Schiff bases obtained using aminoalcohols open the door to the synthesis of homo- and heterometallic clusters with various nuclearities and surprising topologies of the metal centers. Several relevant structural types are reviewed. The heterobinuclear 3d-3d' and 3d-4f complexes are valuable building-blocks for the synthesis of heterotrimetallic systems. Beyond the richness of this chemistry, the complexes obtained from o-vanillin-based Schiff ligands show interesting properties: magnetism, luminescence, chirality, catalysis, cytotoxicity, and ferroelectricity. This paper reviews recent data that illustrate a very fertile and dynamic research field in coordination chemistry and materials science. PMID:26282536

  7. Ni(II) complexes with Schiff bases derived from amino sugars.

    PubMed

    Costamagna, Juan; Lillo, Luis E; Matsuhiro, Betty; Noseda, Miguel D; Villagrn, Manuel

    2003-07-22

    It was found by 1H and 13C NMR spectroscopy that the Schiff base, 2-deoxy-2-(2-hydroxybenzaldimino)-D-glucopyranose exhibits enol-imine-keto-amine and anomeric equilibria in methanolic, and in dimethyl sulfoxide solutions. The reaction of the Schiff base with nickel acetate gave the bidentate, mononuclear Ni(II) complex that was characterized by spectroscopic methods and by cyclic voltammetry. The coordination of the Schiff base to the metal is through the enol-imine tautomeric form, and the anomeric equilibrium remains in dimethyl sulfoxide solutions. This complex was also obtained by reaction of D-glucosamine with Ni(II) salicylaldehydate. The same reaction was employed for the synthesis of bis-N-[2-deoxy-D-galactopyranosyl-2-(2-hydroxybenzaldiminate)]Ni(II). The small paramagnetic shifts of the 1H NMR resonances of the complexes suggest that paramagnetic species are present in low proportions. PMID:12860424

  8. Crossing the Traditional Boundaries: Salen-Based Schiff Bases for Thermal Protective Applications.

    PubMed

    Naik, Anil D; Fontaine, Gaëlle; Bellayer, Séverine; Bourbigot, Serge

    2015-09-30

    A broad spectrum of applications of "Salen"-based Schiff bases tagged them as versatile multifunctional materials. However, their applicability is often bounded by a temperature threshold and, thus, they have rarely been used for high temperature applications. Our investigation of a classical Schiff base, N,N'-bis(4-hydroxysalicylidene)ethylenediamine (L2), reveals that it displays an intriguingly combative response to an elevated temperature/fire scenario. L2 resists and regulates thermal degradation by forming an ablative surface, and acts as a thermal shield. A polycondensation via covalent cross-linking, which forms a hyperbranched cross-linked resin is found to constitute the origin of the ablative surface. This is a unique example of a resin formation produced with a Schiff base, that mimicks the operational strategy of a high-heat resistant phenolic resin. Further applicability of L2, as a flame retardant, was tested in an engineering polymer, polyamide-6. It was found that it reinforces the polymer against fire risks by the formation of an intumescent coating. This paves the way for a new strategic avenue in safeguarding polymeric materials toward fire risks. Further, this material represents a promising start for thermal protective applications. PMID:26348914

  9. Fluorescence and excited state dynamics of the deprotonated Schiff base retinal in proteorhodopsin.

    PubMed

    Bhl, Elena; Braun, Markus; Lakatos, Andrea; Glaubitz, Clemens; Wachtveitl, Josef

    2015-09-01

    The UV light absorbing species of proteorhodopsin with deprotonated Schiff base retinal was investigated using steady-state fluorescence and femtosecond pump-probe spectroscopy. Compared to the all-trans retinal with protonated Schiff base, the deprotonated chromophore absorbs at 365 nm and exhibits a blue-shifted fluorescence spectrum. The unusually long-lived excited state decays bi-exponentially with time constants of 8 ps and 130 ps to form a deprotonated 13-cis retinal as the primary photo-product. PMID:26083266

  10. Ground and Excited States of Retinal Schiff Base Chromophores by Multiconfigurational Perturbation Theory

    PubMed Central

    Sekharan, Sivakumar; Weingart, Oliver; Buss, Volker

    2006-01-01

    We have studied the wavelength dependence of retinal Schiff base absorbencies on the protonation state of the chromophore at the multiconfigurational level of theory using second order perturbation theory (CASPT2) within an atomic natural orbital basis set on MP2 optimized geometries. Quantitative agreement between calculated and experimental absorption maxima was obtained for protonated and deprotonated Schiff bases of all-trans- and 11-cis-retinal and intermediate states covering a wavelength range from 610 to 353 nm. These data will be useful as reference points for the calibration of more approximate schemes. PMID:16648170

  11. Triorganotin(IV) complexes with biologically potent schiff bases: infrared, ?Sn spectral characteristics and antimicrobial applications.

    PubMed

    Rehman, W; Khan, J; Muhammad, B; Shah, S W H; Rashid, R

    2012-05-01

    This review paper has attempted information specific to the title compound. This survey of the literature data provides useful information about the design and stabilities of the triorganotin with biologically active ligands. Up to now, considerable efforts have been made to synthesize and characterize triorganotin(IV) schiff base complexes with the general formulae R3ML [R = organic group, M: Sn and L: schiff base] and many studies have been focused in order to understand bioassay results. Users with an interest in this substance are strongly encouraged for future research that this is still a very open field. PMID:22303951

  12. Syntheses, crystal structure and biological evaluation of Schiff bases and copper complexes derived from 4-formylpyrazolone

    NASA Astrophysics Data System (ADS)

    Joseph, V. A.; Pandya, J. H.; Jadeja, R. N.

    2015-02-01

    Two new pyrazolone based Schiff base ligands 4-((2,4-dimethylphenylimino)methyl)-4,5-dihydro-3-methyl-1-p-tolyl-1H-pyrazol-5-ol [PTPMP-ME] and 4-((3,4-difluorophenylimino)methyl)-4,5-dihydro-3-methyl-1-p-tolyl-1H-pyrazol-5-ol [PTPMP-F] were synthesized. Using these Schiff base ligands two new Copper(II) complexes, [Cu(PTPMP-ME)2] (1) and [Cu(PTPMP-F)2] (2) were synthesized. The ligands and their copper complexes were characterized by IR, 1H NMR, mass, UV-Visible spectroscopy, molar conductivity and magnetic measurement. The molecular geometry of Schiff base ligand PTPMP-ME and copper complexes were determined by single-crystal X-ray analysis. On the basis of single crystal X-ray analysis and spectroscopic techniques, square planar geometry of the complexes was proposed. The Schiff base ligands and their metal complexes were tested for antimicrobial activity against Gram-positive bacteria; Staphylococcus aureus and Bacillus subtilis and Gram-negative bacteria; Escherichia coli and Pseudomonas aeruginosa.

  13. Olefin Metathesis Mediated By: - Schiff Base Ru-Alkylidenes -Ru-Alkylidenes Bearing Unsymmetrical NH Ligands

    NASA Astrophysics Data System (ADS)

    Monsaert, Stijn; Voort, Pascal Van Der; Ledoux, Nele; Allaert, Bart; Drozdzak, Renata; Verpoort, Francis

    The classic Grubbs second-generation complex 2 was modified through 1. The introduction of a bidentate Schiff base ligand 2. Changes in the amino side groups of the NHC ligand Representative olefin metathesis test reactions show the effects induced by the ligand modifications and demonstrate some interesting new properties of the described catalysts. catalysts.

  14. Rapid photodynamics of vitamin B6 coenzyme pyridoxal 5'-phosphate and its Schiff bases in solution.

    PubMed

    Hill, Melissa P; Carroll, Elizabeth C; Toney, Michael D; Larsen, Delmar S

    2008-05-01

    The active form of vitamin B6, pyridoxal 5'-phosphate (PLP), is an important cofactor for numerous enzymes in amine and amino acid metabolism. Presented here is the first femtosecond transient absorption study of free PLP and two Schiff bases, PLP-valine and PLP-alpha-aminoisobutyric acid (AIB), in solution. Photoexcitation of free PLP leads to efficient triplet formation with an internal conversion rate that increases with increasing pH. The measured excited-state kinetics of the PLP-valine Schiff base exhibits a dramatic deuterium dependence as a result of excited-state proton transfer (ESPT) of the Calpha hydrogen in the amino acid substrate. This is consistent with formation of the key reaction carbanionic intermediate (quinonoid), which is resonance stabilized by the electron-deficient, conjugated pi system of the Schiff base/pyridine ring. The transient absorption signals of the PLP-Schiff base with alpha-methylalanine (2-aminoisobutyric acid), which does not have a Calpha proton, lack an observable deuterium effect, verifying ESPT formation of the quinonoid intermediate. In contrast to previous studies, no dependence on the excitation wavelength of the femtosecond kinetics is observed with PLP or PLP-valine, which suggests that a rapid (<250 fs) tautomerization occurs between the enolimine (absorbing at 330 nm) and ketoenamine (absorbing at 410 nm) tautomers in solution. PMID:18416573

  15. Towards dipyrrins: oxidation and metalation of acyclic and macrocyclic Schiff-base dipyrromethanes.

    PubMed

    Pankhurst, James R; Cadenbach, Thomas; Betz, Daniel; Finn, Colin; Love, Jason B

    2015-02-01

    Oxidation of acyclic Schiff-base dipyrromethanes cleanly results in dipyrrins, whereas the macrocyclic 'Pacman' analogues either decompose or form new dinuclear copper(ii) complexes that are inert to ligand oxidation; the unhindered hydrogen substituent at the meso-carbon allows new structural motifs to form. PMID:25563854

  16. Amido-Schiff base derivatives as colorimetric fluoride sensor: Effect of nitro substitution on the sensitivity and color change.

    PubMed

    Ghosh, Soumen; Alam, Md Akhtarul; Ganguly, Aniruddha; Guchhait, Nikhil

    2015-10-01

    A series of Schiff bases synthesized by the condensation of benzohydrazide and -NO2 substituted benzaldehyde have been used as selective fluoride ion sensor. Test paper coated with these synthetic Schiff bases (test kits) can detect fluoride ion selectively with a drastic color change and detection can be achieved by just using the naked-eye without the help of any optical instrument. Interestingly, the position of -NO2 group in the amido Schiff bases has an effect on the sensitivity as well as on the change of color of species. PMID:26002437

  17. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, Robert E.; Dolbeare, Frank A.

    1979-01-01

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 5-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

  18. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, Robert E. [557 Escondido Cir., Livermore, CA 94550; Dolbeare, Frank A. [5178 Diane La., Livermore, CA 94550

    1980-10-21

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes.

  19. Fluorescence method for enzyme analysis which couples aromatic amines with aromatic aldehydes

    DOEpatents

    Smith, R.E.; Dolbeare, F.A.

    1980-10-21

    Analysis of proteinases is accomplished using conventional amino acid containing aromatic amine substrates. Aromatic amines such as 4-methoxy-2-naphthylamine (4M2NA), 2-naphthylamine, aminoisophthalic acid dimethyl ester, p-nitroaniline, 4-methoxy-1-aminofluorene and coumarin derivatives resulting from enzymatic hydrolysis of the substrate couples with aromatic aldehydes such as 5-nitrosalicylaldehyde (5-NSA), benzaldehyde and p-nitrobenzaldehyde to produce Schiff-base complexes which are water insoluble. Certain Schiff-base complexes produce a shift from blue to orange-red (visible) fluorescence. Such complexes are useful in the assay of enzymes. No Drawings

  20. Synthesis and spectral studies of metal complexes of a Schiff base derived from (2-amino-5-chlorophenyl)phenyl methanone.

    PubMed

    Mini, S; Sadasivan, V; Meena, S S; Bhatt, Pramod

    2015-12-01

    Some new complexes of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Fe(III) with the Schiff base 5-chloro-2-(furan-2-yl methylamino)phenyl)phenyl methanone has been synthesized and characterized by elemental analysis, spectroscopic data including FT-IR, (1)H NMR, Electronic, ESI mass, Mssbauer & ESR. It has been found that the Schiff base behaves as a neutral bidentate N, O donor which chelates with the metal ions in 1:2 stoichiometry. Magnetic moment and electrolytic conductance data confirms this. The Schiff base and selected complexes were screened for antimicrobial activity. The complexes and the Schiff base were subjected to antioxidant study. The antitumor activity of Co(II) complex was tested by MTT assay. The result indicates the viability of the complex against tested cell lines. PMID:26163782

  1. Investigation of the antioxidant and radical scavenging activities of some phenolic Schiff bases with different free radicals.

    PubMed

    Markovi?, Zoran; ?orovi?, Jelena; Petrovi?, Zorica D; Petrovi?, Vladimir P; Simijonovi?, Duica

    2015-11-01

    The antioxidant properties of some phenolic Schiff bases in the presence of different reactive particles such as ()OH, ()OOH, (CH2=CH-O-O()), and (-)O2 were investigated. The thermodynamic values, ?H BDE, ?H IP, and ?H PA, were used for this purpose. Three possible mechanisms for transfer of hydrogen atom, concerted proton-electron transfer (CPET), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were considered. These mechanisms were tested in solvents of different polarity. On the basis of the obtained results it was shown that SET-PT antioxidant mechanism can be the dominant mechanism when Schiff bases react with radical cation, while SPLET and CPET are competitive mechanisms for radical scavenging of hydroxy radical in all solvents under investigation. Examined Schiff bases react with the peroxy radicals via SPLET mechanism in polar and nonpolar solvents. The superoxide radical anion reacts with these Schiff bases very slowly. PMID:26508294

  2. Preparation, spectral studies, theoretical, electrochemical and antibacterial investigation of a new Schiff base and its some metal complexes

    NASA Astrophysics Data System (ADS)

    Ilhan, S.; Baykara, H.; Seyitoglu, M. S.; Levent, A.; zdemir, S.; Dndar, A.; ztomsuk, A.; Cornejo, M. H.

    2014-10-01

    A new Schiff base ligand, 1,6-Bis(2-(5-bromo-2-hydroxybenzylideneamino)-4-chlorophenoxy)hexane was synthesized. Some Schiff metal complexes of the new Schiff base were prepared by the reaction of some metal salts and the Schiff base. The complexes are non-electrolytes as shown by their molar conductivities (?M). The structures of metal complexes are proposed from elemental analysis, FT-IR, UV-vis, magnetic susceptibility measurements, molar conductivity measurements, mass spectra and thermal gravimetric analysis. In addition theoretical 1H NMR, HOMO-LUMO studies of the ligand; antimicrobial and cyclic voltammetric studies of the compounds were also carried out. In this study antioxidant and antibacterial activities of the compounds were examined via in vitro methods.

  3. Schiff's Bases and Crown Ethers as Supramolecular Sensing Materials in the Construction of Potentiometric Membrane Sensors

    PubMed Central

    Faridbod, Farnoush; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Norouzi, Parviz; Riahi, Siavash

    2008-01-01

    Ionophore incorporated PVC membrane sensors are well-established analytical tools routinely used for the selective and direct measurement of a wide variety of different ions in complex biological and environmental samples. Potentiometric sensors have some outstanding advantages including simple design and operation, wide linear dynamic range, relatively fast response and rational selectivity. The vital component of such plasticized PVC members is the ionophore involved, defining the selectivity of the electrodes' complex formation. Molecular recognition causes the formation of many different supramolecules. Different types of supramolecules, like calixarenes, cyclodextrins and podands, have been used as a sensing material in the construction of ion selective sensors. Schiff's bases and crown ethers, which feature prominently in supramolecular chemistry, can be used as sensing materials in the construction of potentiometric ion selective electrodes. Up to now, more than 200 potentiometric membrane sensors for cations and anions based on Schiff's bases and crown ethers have been reported. In this review cation binding and anion complexes will be described. Liquid membrane sensors based on Schiff's bases and crown ethers will then be discussed.

  4. Effect of hydroxyl group position on adsorption behavior and corrosion inhibition of hydroxybenzaldehyde Schiff bases: Electrochemical and quantum calculations

    NASA Astrophysics Data System (ADS)

    Danaee, I.; Ghasemi, O.; Rashed, G. R.; Rashvand Avei, M.; Maddahy, M. H.

    2013-03-01

    The corrosion inhibition and adsorption of N,N'-bis(n-hydroxybenzaldehyde)-1,3-propandiimine (n-HBP) Schiff bases has been investigated on steel electrode in 1 M HCl by using electrochemical techniques. The experimental results suggest that the highest inhibition efficiency was obtained for 3-HBP. Polarization curves reveal that all studied inhibitors are mixed type. Density functional theory (DFT) at the B3LYP/6-31G(d,p) and B3LYP/3-21G basis set levels and ab initio calculations using HF/6-31G(d,p) and HF/3-21G methods were performed on three Schiff bases. By studying the effects of hydroxyl groups in ortho-, meta-, para- positions, the best one as inhibitor was found to be meta-position of OH in Schiff base (i.e., 3-HBP). The order of inhibition efficiency obtained was corresponded with the order of most of the calculated quantum chemical parameters. Quantitative structure activity relationship (QSAR) approach has been used and a correlation of the composite index of some of the quantum chemical parameters was performed to characterize the inhibition performance of the Schiff bases studied. The results showed that %IE of the Schiff bases was closely related to some of the quantum chemical parameters but with varying degrees/order. The calculated %IE of the Schiff base studied was found to be close to their experimental corrosion inhibition efficiencies.

  5. Preparation, regulation and biological application of a Schiff base fluorescence probe.

    PubMed

    Yin, Ninghua; Diao, Haipeng; Liu, Wen; Wang, Jingru; Feng, Liheng

    2016-01-15

    A facile fluorescence switch with Schiff base units was designed and achieved by nucleophilic addition and dehydration reaction. The fluorescence of the probe can be regulated by metal ions (Al(3+) and Cu(2+)). The whole process shows that the weak fluorescence of the probe enhances with the addition of Al(3+), and then the strong fluorescence of the probe/Al(3+) ensemble reduces by introducing Cu(2+). Meanwhile, the solution color changes of the probe with metal ions can be observed under 365nm UV-vis light from weak light, pale green, green, pale green to weak light. Noticeably, the photo regulation processes of the probe by metal ions can be realized in the biological system and applied in cells imaging. The work provides a new strategy for designing facile regulation probe and develops a new application for Schiff base derivatives. PMID:26282317

  6. A dinuclear cadmium(II) Schiff base thiocyanato complex: crystal structure and fluorescence.

    PubMed

    Shit, Shyamapada; Sankolli, Ravish; Guru Row, Tayur N

    2014-01-01

    A new dinuclear cadmium(II) complex, [Cd(L)(NCS)]2 (1) has been synthesized using a potentially tetradentate Schiff base ligand HL, 2-((E)-(2-(diethylamino)ethylimino)methyl)-6-methoxyphenol, obtained by the condensation of 2-diethylaminoethylamine and o-vanillin, and characterized by different physicochemical techniques. Crystal structure of the title complex was unambiguously established by single crystal X-ray diffraction which reveals that metal centers are connected by bridging phenolato and chelating methoxy oxygen atoms of the coordinating Schiff bases and embedded in severely distorted octahedral geometries. Fluorescence properties of the ligand and its complex, studied at room temperature indicate that later may serve as strong fluorescent emitter. PMID:24664327

  7. Docking of ethanamine Schiff base imines & metal (II) complexes, cytotoxicity & DNA interaction studies

    NASA Astrophysics Data System (ADS)

    Sujarani, S.; Ramu, A.

    2015-01-01

    The present study deals with a series of biologically and stereo chemically important novel transition metal (II) Schiff base chelates. The Cu (II), Co (II), Mn (II) and Ni (II) ions containing complexes were synthesized by using diphenylethanamine and 2-hydroxy/2, 4-dihydroxy/2-hydroxy-4-methoxybenzaldehydes. The synthesized complexes were characterized using micro analytical, IR, NMR, ESI-Mass, UV-Visible, cyclic voltammetry and the EPR spectroscopic techniques. The spectral data evidenced the action of ligands as a neutral bidentate Schiff bases, coordinating through azomethine nitrogen and oxygen atom of hydroxyl group. The interaction studies revealed the groove binding nature of complexes with CT-DNA. The ligand and synthesized metal complexes showed cytotoxicity against cancerous cells. The strong binding affinity of the imine and metal complexes was also confirmed by molecular docking studies.

  8. Synthesis and Fluorescence Properties of Eu(3+), Tb(3+) Complexes with Schiff Base Derivatives.

    PubMed

    Liu, Yanhong; Kong, Weihua; Yang, Zehui; Dai, Ming; Shi, Ling; Guo, Dongcai

    2016-03-01

    Novel Schiff base ligands derived from N'-benzylidene-benzohydrazide (substituted by -H, -CH3, -OCH3, -Cl) and 2-chloro-N-phenylacetamide were synthesized. The solid complexes of rare earth (Eu, Tb) nitrate with these Schiff base ligands were synthesized and characterized by elemental analysis, EDTA titrimetric analysis, thermal analysis, infrared spectra and UV-Vis spectra analysis. The fluorescence properties of rare earth (Eu, Tb) complexes in solid were studied. Under the excitation of ultraviolet light, these complexes exhibited characteristic emission of europium and terbium ions. The results showed that the ligand favored energy transfer to the emitting energy of Eu and Tb ions. Effects of different ligands on the fluorescence intensity of rare earth (Eu, Tb) complexes had been discussed. The electrochemical properties of rare earth (Eu, Tb) complexes were also investigated. PMID:26658796

  9. Coordination chemistry, thermodynamics and DFT calculations of copper(II) NNOS Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Esmaielzadeh, Sheida; Azimian, Leila; Shekoohi, Khadijeh; Mohammadi, Khosro

    2014-12-01

    Synthesis, magnetic and spectroscopy techniques are described for five copper(II) containing tetradentate Schiff bases are synthesized from methyl-2-(N-2";-aminoethane), (1-methyl-2";-aminoethane), (3-aminopropylamino)cyclopentenedithiocarboxylate. Molar conductance and infrared spectral evidences indicate that the complexes are four-coordinate in which the Schiff bases are coordinated as NNOS ligands. Room temperature ?eff values for the complexes are 1.71-1.80 B.M. corresponding to one unpaired electron respectively. The formation constants and free energies were measured spectrophotometrically, at constant ionic strength 0.1 M (NaClO4), at 25?C in DMF solvent. Also, the DFT calculations were carried out to determine the structural and the geometrical properties of the complexes. The DFT results are further supported by the experimental formation constants of these complexes.

  10. Preparation, regulation and biological application of a Schiff base fluorescence probe

    NASA Astrophysics Data System (ADS)

    Yin, Ninghua; Diao, Haipeng; Liu, Wen; Wang, Jingru; Feng, Liheng

    2016-01-01

    A facile fluorescence switch with Schiff base units was designed and achieved by nucleophilic addition and dehydration reaction. The fluorescence of the probe can be regulated by metal ions (Al3 + and Cu2 +). The whole process shows that the weak fluorescence of the probe enhances with the addition of Al3 +, and then the strong fluorescence of the probe/Al3 + ensemble reduces by introducing Cu2 +. Meanwhile, the solution color changes of the probe with metal ions can be observed under 365 nm UV-vis light from weak light, pale green, green, pale green to weak light. Noticeably, the photo regulation processes of the probe by metal ions can be realized in the biological system and applied in cells imaging. The work provides a new strategy for designing facile regulation probe and develops a new application for Schiff base derivatives.

  11. Synthesis, antimicrobial activity of Schiff base compounds of cinnamaldehyde and amino acids.

    PubMed

    Wang, Hui; Yuan, Haijian; Li, Shujun; Li, Zhuo; Jiang, Mingyue

    2016-02-01

    The purpose of this study was to synthesize hydrophilic cinnamaldehyde Schiff base compounds and investigate those bioactivity. A total of 24 Schiff base compounds were synthesized using a simple approach with 3 cinnamaldehyde derivates and 8 amino acids as raw materials. The structures of synthesized compounds were confirmed using FTIR, (1)HNMR, HRMS purity and melting point. The antimicrobial activities of new compounds were evaluated with fluconazole and ciprofloxacin as the control against Aspergillus niger, Penicillium citrinum, Escherichia coli and Staphylococcus aureus. Findings show that major compounds exhibited significant bioactivity. Results from the structure-activity relationship suggest that both -p-Cl on benzene ring of cinnamaldehyde and the number of -COOK of amino acid salts significantly contributed to antimicrobial activity. PMID:26774583

  12. Cationic schiff base amphiphiles and their metal complexes: Surface and biocidal activities against bacteria and fungi.

    PubMed

    Negm, N A; Zaki, M F; Salem, M A I

    2010-05-01

    A series of cationic surfactants containing schiff base groups was synthesized by condensation of four fatty amines namely: dodecyl, tetradecyl, hexadecyl and octadecyl amine and 4-diethyl aminobenzaldehyde (1-4), as well as their metal complexes with divalent transition metal ions including Co, Cu and Mn (5-16). The surface activities of the synthesized surfactants were influenced by their chemical structures and the type of the transition metals. The biological activity measurements of the parent cationic schiff bases showed high efficacy against Gram positive and Gram negative bacterial strains and fungi. While on complexation, the biocidal activity was increased remarkably. The biocidal activity of the tested compounds against sulfur reducing bacteria showed promising results in the field of biocide applications. PMID:20167455

  13. Synthesis, fluorescence study and biological evaluation of three Zn(II) complexes with Paeonol Schiff base

    NASA Astrophysics Data System (ADS)

    Qin, Dong-dong; Yang, Zheng-yin; Qi, Gao-fei

    2009-10-01

    The synthesis of three Paeonol Schiff base ligand and their Zn(II) complexes are reported. The complexes were fully characterized by IR, 1H NMR, elemental analysis and molar conductivity. The experiment results show the three Zn(II) complexes can emit bright fluorescence at room temperature in DMF solution and solid state. The fluorescence quantum yields ( ?) of three Schiff base ligands and their Zn(II) complexes were calculated using quinine sulfate as the reference with a known ?R of 0.546 in 1.0N sulfuric acid. Furthermore, in order to develop these Zn(II) complexes' biological value, the antioxidant activities against hydroxyl radicals (OH rad ) were evaluated. The results show the three complexes possess excellent ability to scavenge hydroxyl radicals.

  14. Novel polymer anchored Cr(III) Schiff base complexes: synthesis, characterization and antimicrobial properties.

    PubMed

    Selvi, Canan; Nartop, Dilek

    2012-09-01

    New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV-Vis, TG-DTA and (1)H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH). PMID:22622060

  15. Studies on synthesis, characterization, DNA interaction and cytotoxicity of ruthenium(II) Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Raja, Gunasekaran; Butcher, Ray. J.; Jayabalakrishnan, Chinnasamy

    The synthesis and characterization of three hexa-coordinated ruthenium(II) Schiff base complexes of the type [RuCl(CO)(B)L] (B = PPh3/AsPh3/py and L = monobasic tridentate Schiff base ligand derived by the condensation of salicylaldehyde with 4-aminoantipyrine) are reported. IR, electronic, NMR and mass spectral data of the complexes are discussed. An octahedral geometry has been tentatively proposed for all the complexes. DNA binding properties of the ligand and its ruthenium(II) complexes have been investigated by electronic absorption spectroscopy. Two of the complexes were tested for DNA cleavage property. Finally, in vitro study of the cytotoxicity of the ligand and the complex [RuCl(CO)(PPh3)L] on HeLa were tested. The IC50 value for the ligand and the complex were 52.3 and 31.6 ?m respectively.

  16. Non-linear optical analyses of nitro aniline derived Schiff bases of 9-anthraldehyde

    NASA Astrophysics Data System (ADS)

    Vijayalakshmi, S.; Kalyanaraman, S.

    2013-01-01

    The synthesis and non-linear optical properties of nitro aniline derived Schiff bases of 9-anthraldehyde were carried out. The compounds were characterized using FT-IR, Raman and UV-Vis spectroscopies. The FT-IR and Raman spectral data revealed the confirmation of Schiff bases with the absorption band assignable to the stretching of Cdbnd N band. The charge transfer (CT) interaction between the donor and acceptor molecules were confirmed through ?max of the UV-Vis spectra. The UV-Vis analysis indicated, bathochromic shift in the compounds, implying a non-zero first order molecular hyperpolarizability (?) which are translated into macroscopic non-linearity ?2. To investigate the solid state macroscopic non-zero non-linear optical response, ?2, (second harmonic generation) the Kurtz and Perry method was used. This happens to be the first report on the non-linear optical analysis of these compounds.

  17. Novel polymer anchored Cr(III) Schiff base complexes: Synthesis, characterization and antimicrobial properties

    NASA Astrophysics Data System (ADS)

    Selvi, Canan; Nartop, Dilek

    2012-09-01

    New polymer-bound Schiff bases and Cr(III) complexes have been synthesized by the reaction of 4-benzyloxybenzaldehyde, polymer-bound with 2-aminophenol, 2-amino-4-chlorophenol and 2-amino-4-methylphenol. The structure of polymeric-Schiff bases and their Cr(III) complexes have been characterized by elemental analyses, magnetic measurements, IR, UV-Vis, TG-DTA and 1H-NMR. All these compounds have also been investigated for antibacterial activity by the well-diffusion method against Staphylococcus aureus (RSKK-07035), Shigella dysenteria type 10 (RSKK 1036), Listeria monocytogenes 4b(ATCC 19115, Escherichia coli (ATCC 1230), Salmonella typhi H (NCTC 901.8394), Staphylococcus epidermis (ATCC 12228), Brucella abortus (RSKK-03026), Micrococcs luteus (ATCC 93419, Bacillus cereus sp., Pseudomonas putida sp. and for antifungal activity against Candida albicans (Y-1200-NIH).

  18. Synthesis and characterization of modified Schiff base silatranes (MSBS) via 'Click Silylation'

    NASA Astrophysics Data System (ADS)

    Singh, Gurjaspreet; Arora, Aanchal; Mangat, Satinderpal Singh; Singh, Jandeep; Chaudhary, Sunita; Kaur, Navneet; Choquesillo-Lazarte, Duane

    2015-01-01

    Schiff bases (1a-1d) were modified into terminal alkynes (2a-2d) which on Click Silylation with 3-azidopropyltriethoxysilane (AzPTES) yielded 1,2,3-triazole capped triethoxysilanes (3a-3d). These triethoxysilanes on transesterification with triethanolamine afforded corresponding modified Schiff base silatranes (MSBS) (4a-4d) in high yield and purity. All the synthesized compounds were well characterized by IR, NMR (1H, 13C), mass spectroscopy, elemental analysis and complete structure elucidation by X-ray diffraction studies for 2b and 4b. Starting alkynes and final silatranes are further compared by their absorption spectra and TGA analysis. Synthesized MSBS are the first compounds of their kind which being hydrolytically stable can be put to further use in the field of medical and material research.

  19. Photostabilizing Efficiency of PVC in the Presence of Schiff Bases as Photostabilizers.

    PubMed

    Yousif, Emad; Al-Amiery, Ahmed A; Kadihum, Abdulhadi; Kadhum, Abdul Amir H; Mohamad, Abu Bakar

    2015-01-01

    The photostabilization of polyvinyl chloride (PVC) films by Schiff bases was investigated. Polyvinyl chloride films containing 0.5 wt % Schiff bases were produced using the same casting method as that used for additive-free PVC films from tetrahydrofuran (THF) solvent. The photostabilization activities of these compounds were determined by monitoring the carbonyl, polyene and hydroxyl indices with irradiation time. The changes in viscosity average molecular weight of PVC with irradiation time were also monitored using THF as a solvent. The quantum yield of chain scission (Φcs) for the studied complexes in PVC was estimated to range between 4.72 and 8.99 × 10(-8). According to the experimental results, several mechanisms were suggested, depending on the structure of the additive. Ultra violet (UV) absorption, peroxide decomposition and radical scavenging were suggested as the photostabilizing mechanisms. PMID:26556323

  20. Synthesis, Characterization and Biocidal Activities of Some Schiff Base Metal Complexes

    PubMed Central

    Neelakantan, M. A.; Esakkiammal, M.; Mariappan, S. S.; Dharmaraja, J.; Jeyakumar, T.

    2010-01-01

    Some new mixed ligand complexes (1-5) of type ML'B (M(II)=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); HL'= o-vanillidene-2-aminobenzothiazole; B= 1,10-phenanthroline) and Schiff base metal complexes of types (ML2") (6-10) and (M2L") (11-15) (HL"= o-vanillidene-2-amino-N-(2-pyridyl)-benzene sulfonamide) were synthesized and characterized by elemental analysis and spectral (IR, 1H NMR and 13C NMR) studies. The free ligands and their metal complexes have been screened for their in vitro biological activities against bacteria, fungi and yeast. The metal complexes show more potent activities compared with Schiff base ligands. PMID:20838526

  1. Synthesis, characterization and biocidal activities of some schiff base metal complexes.

    PubMed

    Neelakantan, M A; Esakkiammal, M; Mariappan, S S; Dharmaraja, J; Jeyakumar, T

    2010-03-01

    Some new mixed ligand complexes (1-5) of type ML'B (M(II)=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); HL'= o-vanillidene-2-aminobenzothiazole; B= 1,10-phenanthroline) and Schiff base metal complexes of types (ML(2)") (6-10) and (M(2)L") (11-15) (HL"= o-vanillidene-2-amino-N-(2-pyridyl)-benzene sulfonamide) were synthesized and characterized by elemental analysis and spectral (IR, (1)H NMR and (13)C NMR) studies. The free ligands and their metal complexes have been screened for their in vitro biological activities against bacteria, fungi and yeast. The metal complexes show more potent activities compared with Schiff base ligands. PMID:20838526

  2. One-dimensional organic photoconductive nanoribbons built on Zn-Schiff base complex

    SciTech Connect

    Liu Li; Shao Mingwang; Wang Xiuhua

    2010-03-15

    One-dimensional organic nanoribbons built on N-p-nitrophenylsalicylaldimine zinc complex were synthesized via a facile solvothermal route. The scanning electron microscope images revealed that the as-synthesized products were ribbon-like with width mainly of 300-600 nm, thickness of about 50 nm, and length of up to tens of micrometers. Fourier transform infrared spectrum was employed to characterize the structure. Ultraviolet-visible absorption and photoluminescence spectra showed that the products had good photoluminescent property and exhibited blue emission. The conductivity of a bundle of nanoribbons was also measured, which showed that the Schiff base zinc nanoribbons had good photoconductive property. This work might enrich the organic photoconductive materials and be applicable in light-controlled micro-devices or nano-devices in the future. - Graphical abstract: The Schiff base zinc nanoribbons nanowires exhibited good photoresponse under an incandescent lamp, which indicated their potential application as organic semiconductive or photoconductive nanodevices in the future.

  3. A novel Schiff-base as a Cu(II) ion fluorescent sensor in aqueous solution

    NASA Astrophysics Data System (ADS)

    Gndz, Z. Yurtman; Gndz, C.; zp?nar, C.; Urucu, O. Ayd?n

    2015-02-01

    A new fluorescent Cu(II) sensor (L) obtained from the Schiff base of 5,5?-methylene-bis-salicylaldehyde with amidol (2,4-diaminophenol) was synthesized and characterized by FT-IR, MS, 1H NMR, 13C NMR techniques. In the presence of pH 6.5 (KHPO4-Na2HPO4) buffer solutions, copper reacted with L to form a stable 2:1 complex. Fluorescence spectroscopic study showed that Schiff base is highly sensitive towards Cu(II) over other metal ions (K+, Na+, Al3+, Ni2+, Co2+, Fe3+, Zn2+, Pb2+) in DMSO/H2O (30%, v/v). The sensor L was successfully applied to the determination of copper in standard reference material. The structural properties and molecular orbitals of the complex formed between L and Cu2+ ions were also investigated using quantum chemical computations.

  4. Transition Metal(II) Complexes with Cefotaxime-Derived Schiff Base: Synthesis, Characterization, and Antimicrobial Studies

    PubMed Central

    Amzoiu, Emilia; Spnu, Cezar Ionu?

    2014-01-01

    New [ML2(H2O)2] complexes, where M?=?Co(II), Ni(II), Cu(II), and Zn(II) while L corresponds to the Schiff base ligand, were synthesized by condensation of cefotaxime with salicylaldehyde in situ in the presence of divalent metal salts in ethanolic medium. The complexes were characterized by elemental analyses, conductance, and magnetic measurements, as well as by IR and UV-Vis spectroscopy. The low values of the molar conductance indicate nonelectrolyte type of complexes. Based on spectral data and magnetic moments, an octahedral geometry may be proposed for Co(II), Ni(II), and Zn(II) complexes while a tetragonal geometry for Cu(II) complex. Molecular structure of the Schiff base ligand and its complexes were studied using programs dedicated to chemical modeling and quantomolecular calculation of chemical properties. All the synthesized complexes were tested for in vitro antibacterial activity against some pathogenic bacterial strains, namely Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus. The MIC values shown by the complexes against these bacterial strains revealed that the metal complexes possess superior antibacterial activity than the Schiff base. PMID:24688454

  5. In vitro anticancer activities of Schiff base and its lanthanum complex.

    PubMed

    Neelima; Poonia, Kavita; Siddiqui, Sahabjada; Arshad, Md; Kumar, Dinesh

    2016-02-15

    Schiff base metal complexes are well-known to intercalate DNA. The La(III) complexes have been synthesized such that they hinder with the role of the topoisomerases, which control the topology of DNA during the cell-division cycle. Although several promising chemotherapeutics have been developed, on the basis of Schiff base metal complex DNA intercalating system they did not proceed past clinical trials due to their dose-limiting toxicity. Herein, we discuss an alternative compound, the La(III) complex, [La(L(1))2Cl3]·7H2O based on a Schiff base ligand 2,3-dihydro-1H-indolo-[2,3-b]-phenazin-4(5H)-ylidene)benzothiazole-2-amine (L(1)), and report in vitro cell studies. Results of antitumor activity using cell viability assay, reactive oxygen species (ROS) generation and nuclear condensation in PC-3 (Human, prostate carcinoma) cells show that the metal complex is more potent than ligand. La(III) complexes have been synthesized by reaction of lanthanum(III) salt in 1:2M ratio with ligands L(1) and 3-(ethoxymethylene)-2,3-dihydro-1H-indolo[2,3-b]-phenazin-4(5H)-ylidene)benzathiazole-2-amine (L(2)) in methanol. The ligands and their La(III) complexes were characterized by molar conductance, magnetic susceptibility, elemental analyses, FT-IR, UV-Vis, (1)H/(13)C NMR, thermogravimetric, XRD, and SEM analysis. PMID:26619196

  6. In vitro anticancer activities of Schiff base and its lanthanum complex

    NASA Astrophysics Data System (ADS)

    Neelima; Poonia, Kavita; Siddiqui, Sahabjada; Arshad, Md; Kumar, Dinesh

    2016-02-01

    Schiff base metal complexes are well-known to intercalate DNA. The La(III) complexes have been synthesized such that they hinder with the role of the topoisomerases, which control the topology of DNA during the cell-division cycle. Although several promising chemotherapeutics have been developed, on the basis of Schiff base metal complex DNA intercalating system they did not proceed past clinical trials due to their dose-limiting toxicity. Herein, we discuss an alternative compound, the La(III) complex, [La(L1)2Cl3]·7H2O based on a Schiff base ligand 2,3-dihydro-1H-indolo-[2,3-b]-phenazin-4(5H)-ylidene)benzothiazole-2-amine (L1), and report in vitro cell studies. Results of antitumor activity using cell viability assay, reactive oxygen species (ROS) generation and nuclear condensation in PC-3 (Human, prostate carcinoma) cells show that the metal complex is more potent than ligand. La(III) complexes have been synthesized by reaction of lanthanum(III) salt in 1:2 M ratio with ligands L1 and 3-(ethoxymethylene)-2,3-dihydro-1H-indolo[2,3-b]-phenazin-4(5H)-ylidene)benzathiazole-2-amine (L2) in methanol. The ligands and their La(III) complexes were characterized by molar conductance, magnetic susceptibility, elemental analyses, FT-IR, UV-Vis, 1H/13C NMR, thermogravimetric, XRD, and SEM analysis.

  7. Hydrogen evolution catalyzed by a cobalt complex containing an asymmetric Schiff-base ligand.

    PubMed

    Armstrong, Jessica E; Crossland, Patrick M; Frank, Mariah A; Van Dongen, Matthew J; McNamara, William R

    2016-04-01

    A cobalt(iii) complex containing an asymmetric Schiff-base ligand has been found to be active for proton reduction. Catalysis occurs at -1.2 V vs. Fc(+)/Fc (0.56 V vs. NHE), resulting in an overpotential of 350 mV. Additionally, the complex is active with a turnover frequency of 420 s(-1). An enhancement in activity is observed upon addition of water. PMID:26948148

  8. A novel Schiff base: Synthesis, structural characterisation and comparative sensor studies for metal ion detections

    NASA Astrophysics Data System (ADS)

    Köse, Muhammet; Purtas, Savas; Güngör, Seyit Ali; Ceyhan, Gökhan; Akgün, Eyup; McKee, Vickie

    2015-02-01

    A novel Schiff base ligand was synthesized by the condensation reaction of 2,6-diformylpyridine and 4-aminoantipyrine in MeOH and characterised by its melting point, elemental analysis, FT-IR, 1H, 13C NMR and mass spectroscopic studies. Molecular structure of the ligand was determined by single crystal X-ray diffraction technique. The electrochemical properties of the Schiff base ligand were studied in different solvents at various scan rates. Sensor ability of the Schiff base ligand was investigated by colorimetric and fluorometric methods. Visual colour change of the ligand was investigated in MeOH solvent in presence of various metal ions Na+, Mg2+, Al3+, K+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+. Upon addition of Al3+ ion into a MeOH solution of the ligand, an orange colour developed which is detectable by naked eye. Fluorescence emission studies showed that the ligand showed single emission band at 630-665 nm upon excitation at 560 nm. Addition of metal ions Na+, Mg2+, K+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ (1:1 M ratio) cause fluorescence quenching, however addition of Al+3 resulted in an increase in fluorescence intensity. No significant variation was observed in the fluorescence intensity caused by Al3+ in presence of other metal ions. Therefore, the Schiff base ligand can be used for selective detection of Al3+ ions in the presence of the other metal ions studied.

  9. A hyperbranched conjugated Schiff base polymer network: a potential negative electrode for flexible thin film batteries.

    PubMed

    Sun, Yubao; Sun, Yahui; Pan, Qiyun; Li, Gai; Han, Bo; Zeng, Danli; Zhang, Yunfeng; Cheng, Hansong

    2016-02-01

    A hyperbranched conjugated Schiff base polymer network was synthesized by condensation between 4,4',4''-nitrilotribenzaldehyde and p-phenylenediamine. The material exhibits excellent rate capability and long cycle life for lithium storage. Coupled with lower electrode potential (0.7 V vs. Li(+)/Li), it may be well suited for fully flexible thin film polymeric batteries as the negative electrode. PMID:26785361

  10. Two Schiff-base fluorescent sensors for selective sensing of aluminum (III): Experimental and computational studies

    NASA Astrophysics Data System (ADS)

    Qin, Jing-Can; Cheng, Xiao-ying; Fang, Ran; Wang, Ming-fang; Yang, Zheng-yin; Li, Tian-rong; Li, Yong

    2016-01-01

    Two Schiff-base fluorescent sensors have been synthesized, which both can act as fluorescent probes for Al3+, upon addition of Al3+, they exhibit a large fluorescence enhancement which might be attributed to the formation of 1:1 ligand-Al complexes which inhibit photoinduced electron transfer (PET) progress, and that the proposed binding modes of the sensors and Al3+ are identified by theoretical calculations.

  11. Two Schiff-base fluorescent sensors for selective sensing of aluminum (III): Experimental and computational studies.

    PubMed

    Qin, Jing-Can; Cheng, Xiao-Ying; Fang, Ran; Wang, Ming-Fang; Yang, Zheng-Yin; Li, Tian-Rong; Li, Yong

    2016-01-01

    Two Schiff-base fluorescent sensors have been synthesized, which both can act as fluorescent probes for Al(3+), upon addition of Al(3+), they exhibit a large fluorescence enhancement which might be attributed to the formation of 1:1 ligand-Al complexes which inhibit photoinduced electron transfer (PET) progress, and that the proposed binding modes of the sensors and Al(3+) are identified by theoretical calculations. PMID:26232579

  12. Synthesis, characterization, and biological evaluation of Schiff base-platinum(II) complexes

    NASA Astrophysics Data System (ADS)

    Shiju, C.; Arish, D.; Bhuvanesh, N.; Kumaresan, S.

    2015-06-01

    The platinum complexes of Schiff base ligands derived from 4-aminoantipyrine and a few substituted aldehydes were synthesized and characterized by elemental analysis, mass, 1H NMR, IR, electronic spectra, molar conductance, and powder XRD. The structure of one of the ligands L5 was confirmed by a single crystal XRD analysis. The Schiff base ligand crystallized in the triclinic, space group P-1 with a = 7.032(2) Ǻ, b = 9.479(3) Ǻ, c = 12.425(4) Ǻ, α = 101.636(3)°, β = 99.633(3)°, γ = 94.040(3)°, V = 795.0(4) Ǻ3, Z = 2, F(0 0 0) = 352, Dc = 1.405 mg/m3, μ = 0.099 mm-1, R = 0.0378, and wR = 0.0967. The spectral results show that the Schiff base ligand acts as a bidentate donor coordinating through the azomethine nitrogen and the carbonyl oxygen atoms. The geometrical structures of these complexes are found to be square planar. Antimicrobial studies indicate that these complexes exhibit better activity than the ligand. The anticancer activities of the complexes have also been studied towards human cervical cancer cell line (HeLa), Colon Cancer Cells (HCT116) and Epidermoid Carcinoma Cells (A431) and it was found that the [Pt(L3)Cl2] complex is more active.

  13. Synthesis, characterization, and biological evaluation of Schiff base-platinum(II) complexes.

    PubMed

    Shiju, C; Arish, D; Bhuvanesh, N; Kumaresan, S

    2015-06-15

    The platinum complexes of Schiff base ligands derived from 4-aminoantipyrine and a few substituted aldehydes were synthesized and characterized by elemental analysis, mass, (1)H NMR, IR, electronic spectra, molar conductance, and powder XRD. The structure of one of the ligands L5 was confirmed by a single crystal XRD analysis. The Schiff base ligand crystallized in the triclinic, space group P-1 with a=7.032(2)?, b=9.479(3)?, c=12.425(4)?, ?=101.636(3), ?=99.633(3), ?=94.040(3), V=795.0(4)?(3), Z=2, F(000)=352, Dc=1.405 mg/m(3), ?=0.099 mm(-1), R=0.0378, and wR=0.0967. The spectral results show that the Schiff base ligand acts as a bidentate donor coordinating through the azomethine nitrogen and the carbonyl oxygen atoms. The geometrical structures of these complexes are found to be square planar. Antimicrobial studies indicate that these complexes exhibit better activity than the ligand. The anticancer activities of the complexes have also been studied towards human cervical cancer cell line (HeLa), Colon Cancer Cells (HCT116) and Epidermoid Carcinoma Cells (A431) and it was found that the [Pt(L3)Cl2] complex is more active. PMID:25782179

  14. Keto-enol tautomerism in asymmetric Schiff bases derived from p-phenylenediamine

    NASA Astrophysics Data System (ADS)

    Uarevi?, Krunoslav; Rub?i?, Mirta; Stilinovi?, Vladimir; Kaitner, Branko; Cindri?, Marina

    2010-12-01

    Reaction of dehydroacetic acid and p-phenylenediamine afforded a monosubstituted Schiff base, I, with the other amino group free. In further reactions with various salicylaldehyde derivatives, I served as a precursor for synthesis of asymmetric bis-Schiff bases. The synthesized compounds are thus comprised of two subunits, dehydroacetic ( dha) and salicylidene ( sal), which are bridged by the phenylene linker. All products were investigated by means of elemental analysis, FT-IR and NMR spectroscopy, thermal methods, powder X-ray diffraction and, when possible, by single crystal X-ray crystallography. Structural and spectroscopic studies revealed that in the bis-products, the dha subunit adopts the keto-amino tautomeric form, while the sal subunit adopts the enol-imino form. Tautomeric forms were not affected if a methoxo group was introduced on the salicylidene ring. Both tautomeric subunits are stabilized by strong resonance-assisted hydrogen bonds, RAHB. The two subunits of the prepared bis-Schiff bases predominantly retain in solution the same tautomeric forms as found in the solid state.

  15. Spectroscopic studies and biological activity of some transition metal complexes of unusual Schiff base

    NASA Astrophysics Data System (ADS)

    Abu Al-Nasr, Ahmad K.; Ramadan, Ramadan M.

    2013-03-01

    Unusual Schiff base ligand, 4-ethanimidoyl-6-[(1E)-N-(2-hydroxy-4-methylphenyl)ethanimidoyl]benzene-1,3-diol, L, was synthesized via catalytic process involving the interaction of some metal ions with a macrocyclic Schiff base (MSB). The transition metal derivatives [ML(H2O)4](NO3)3, M = Cr(III) and Fe(III), [NiL(H2O)4](NO3)2, [ML(H2O)2](NO3)2, M = Zn(II) and Cd(II), [Cl2Pd(?-Cl)2PdL], [PtL(Cl)2] and [PtL(Cl)4] were also synthesized from the corresponding metal species with L. The Schiff bases and complexes were characterized by elemental analysis, mass spectrometry, IR and 1H NMR spectroscopy. The crystal structure of L was determined by X-ray analysis. The spectroscopic studies revealed a variety of structure arrangements for the complexes. The biological activities of L and metal complexes against the Escherchia coli as Gram-negative bacteria and Staphylococcus aureus as Gram-positive bacteria, and the two fungus Aspergillus flavus and Candida albicans were screened. The cytotoxicity of [PtL(Cl)2] complex, a cis-platin analogous, was checked as an antitumor agent on two breast cancer cell lines (MCF7 and T47D) and human liver carcinoma cell line (HepG2).

  16. Electrochemical and structural analysis of a novel symmetrical bis-Schiff base with herringbone packing motif

    NASA Astrophysics Data System (ADS)

    Bali?, Tomislav; Markovi?, Berislav; Medvidovi?-Kosanovi?, Martina

    2015-03-01

    A novel symmetrical bis-Schiff base was synthesized and characterized by means of single crystal X-ray diffraction, FT-IR and NMR spectroscopy, elemental, TG/DSC and electrochemical analysis. The synthesized molecule represents a rare example of symmetrical bis-Schiff base with uncondensed primary amino group as the final reaction product. The molecule is planar, with largest deviation of aminophenyl benzene ring from the plane calculated through the aliphatic chain in the amount of 4.93(1). In the crystal, the molecules are primarily linked by hydrogen bonds involving primary amino groups and weak Csbnd H⋯? interactions. Consequently, these interactions are arranging molecules into herringbone packing motif. The FT-IR and NMR spectra indicated presence of both imino and amino groups in dissolved and solid state, therefore confirming consistency of the studied material and also molecular structure determined by X-ray diffraction. Electrochemical study has shown that the oxidation of the investigated Schiff base is irreversible, diffusion controlled process and that the oxidation products are adsorbed on the glassy carbon electrode surface.

  17. Synthesis and spectral characterization of ternary mixed-vanadyl ?-diketonate complexes with Schiff bases

    NASA Astrophysics Data System (ADS)

    Baranwal, Balram Prasad; Tripathi, Kiran; Singh, Alok Kumar; Tripathi, Saurabh

    2012-06-01

    A new method to synthesize some mononuclear ternary oxovanadium(IV) complexes of the general formula [VO(?-dike)(SB)] (where H?-dike = acetylacetone; benzoylacetone or dibenzoylmethane, HSB = Schiff bases) has been explored by stepwise substitutions of acetylacetonate ion of VO(acac)2 with Schiff bases. The substituted acetylacetone could be fractionated out with p-xylene as an azeotrope. The complexes were characterized by elemental analyses, molecular weight determinations, spectral (electronic, infrared, 1H NMR, EPR and powder XRD) studies, magnetic susceptibility measurements and cyclic voltammetry. Molar conductance measurements indicated the complexes to be non-electrolytes in nitrobenzene. Bidentate chelating nature of ?-diketones and Schiff base anions in the complexes was established by infrared and NMR spectra. Molecular weight determinations confirmed mononuclear nature of the complexes. The EPR spectra illustrated coupling of the unpaired electron with 51V nucleus (I = 7/2). Cyclic voltammograms of all the complexes displayed two-step oxidation processes. The oxidation peak potential corresponded to the quasireversible one-electron oxidation process of the metal center, yielding V(V) species. Transmission electron microscopy (TEM) indicated spherical particles of 200 nm diameter. The synthesized complexes are mixed-ligand complexes showing a considerable hydrolytic stability in which vanadium is having coordination number 5. A square pyramidal geometry around vanadium has been assigned in all the complexes.

  18. Synthesis, X-ray Structure, Spectroscopic Properties and DFT Studies of a Novel Schiff Base

    PubMed Central

    Chen, Kew-Yu; Tsai, Hsing-Yang

    2014-01-01

    A series of Schiff bases, salicylideneaniline derivatives 1–4, was synthesized under mild conditions and characterized by 1H NMR, HRMS, UV-Vis and fluorescence spectra, and single-crystal X-ray diffraction. In solid and aprotic solvents 1–4 exist mainly as E conformers that possess an intramolecular six-membered-ring hydrogen bond. A weak intramolecular C–H···F hydrogen bond is also observed in fluoro-functionalized Schiff base 4, which generates another S(6) ring motif. The C–H···F hydrogen bond further stabilizes its structure and leads it to form a planar configuration. Compounds 1–3 exhibit solely a long-wavelength proton-transfer tautomer emission, while dipole-functionalized Schiff base 4 shows remarkable dual emission originated from the excited-state intramolecular charge transfer (ESICT) and excited-state intramolecular proton transfer (ESIPT) states. Furthermore, the geometric structures, frontier molecular orbitals (MOs) and the potential energy curves for 1–4 in the ground and the first singlet excited state were fully rationalized by density functional theory (DFT) and time-dependent DFT calculations. PMID:25329613

  19. Tuning cobalt(III) Schiff base complexes as activated protein inhibitors.

    PubMed

    Heffern, Marie C; Reichova, Viktorie; Coomes, Joseph L; Harney, Allison S; Bajema, Elizabeth A; Meade, Thomas J

    2015-09-21

    Cobalt(III) Schiff base complexes ([Co(acacen)(L)2](+), where L = NH3) inhibit histidine-containing proteins through dissociative exchange of the labile axial ligands (L). This work investigates axial ligand exchange dynamics of [Co(acacen)(L)2](+) complexes toward the development of protein inhibitors that are activated by external triggers such as light irradiation. We sought to investigate ligand exchange dynamics to design a Co(III) complex that is substitutionally inert under normal physiological conditions for selective activation. Fluorescent imidazoles (C3Im) were prepared as axial ligands in [Co(acacen)(L)2](+) to produce complexes (CoC3Im) that could report on ligand exchange and, thus, complex stability. These fluorescent imidazole reporters guided the design of a new dinuclear Co(III) Schiff base complex containing bridging diimidazole ligands, which exhibits enhanced stability to ligand exchange with competing imidazoles and to hydrolysis within a biologically relevant pH range. These studies inform the design of biocompatible Co(III) Schiff base complexes that can be selectively activated for protein inhibition with spatial and temporal specificity. PMID:26331337

  20. Oxo-molybdenum and oxo-tungsten complexes of Schiff bases relevant to molybdoenzymes.

    PubMed

    Lyashenko, Ganna; Saischek, Gerald; Judmaier, Martina E; Volpe, Manuel; Baumgartner, Judith; Belaj, Ferdinand; Jancik, Vojtech; Herbst-Irmer, Regine; Msch-Zanetti, Nadia C

    2009-08-01

    A series of octahedral dioxomolybdenum(VI) complexes of the type [MoO(2)L(2)] {L = 4-Ar-pent-2-en-ol; L(i-Pr2Ph) with Ar = 2,6-diisopropylphenyl (1); L(Me2Ph) with Ar = 2,6-dimethylphenyl (2), L(MePh) with Ar = 2-methylphenyl (3) and with Ar = phenyl (4)} and dioxotungsten(VI) compounds [WO(2)L(2)] {L(i-Pr2Ph) (5); L(Me2Ph) (6) and L(MePh) (7)} with Schiff bases have been synthesized as models for oxotransferases. Spectroscopic characterization in solution shows with the sterically encumbered ligands L(i-Pr2)Ph and L(Me2)Ph isomerically pure products whereas the ligand with only one substituent in ortho position at the aromatic ring L(MePh) revealed a dynamic mixture of three isomers as confirmed by variable temperature NMR spectroscopy. Single crystal X-ray diffraction analyses of compounds 1, 2, and 4 and showed them to be in the N,N-trans conformation consistent with the larger steric demand at nitrogen. Oxygen atom transfer (OAT) properties towards trimethylphosphine were investigated leading to the isolation of two mononuclear molybdenum(IV) compounds [MoO(PMe(3))(L(Me2Ph))(2)] (8) and [MoO(PMe(3))(L(MePh))(2)] (9) as confirmed by spectroscopic and crystallographic means. The kinetics of OAT between complex [MoO(2)(L(Me2Ph))(2)] (2) and PMe(3) was investigated by UV/Vis spectroscopy under pseudo-first-order conditions revealing single-step reactions with Eyring values of DeltaH(double dagger) = +60.79 kJ mol(-1) and DeltaS(double dagger) = -112 J mol(-1) K(-1) and a first-order dependence of phosphine consistent with a slow nucleophilic attack of the phosphine showing the octahedral geometries of this system to be unfavorable for OAT. Compound 1 showed no OAT reactivity towards PMe(3) emphasizing the influence of sterical properties. Furthermore, the reactivity of the reduced compounds [MoO(PMe(3))(L(Me2Ph))(2)] (8) and [MoO(PMe(3))(L(MePh))(2)] (9) towards molecular oxygen was investigated leading, in the case of 8, to the substitution of PMe(3) by O(2) under formation of the peroxo compound [MoO(O(2))(L(Me2Ph))(2)] (10). In contrast, the analogous reaction employing 9 led to oxidation forming the dioxo compound [MoO(2)(L(MePh))(2)] (3). PMID:20449078

  1. Colorimetric chemosensor for multi-signaling detection of metal ions using pyrrole based Schiff bases

    NASA Astrophysics Data System (ADS)

    Udhayakumari, Duraisamy; Velmathi, Sivan

    2014-03-01

    Pyrrole based Schiff bases act as a highly sensitive probe for metal ions in aqueous medium. Both receptors R1 and R2 are sensitive towards Fe3+, Cu2+, Hg2+ and Cr3+ among the other metal ions. The sensing ability of the receptors are investigated via colorimetric, optical and emission spectroscopic studies. The binding stoichiometries of R1 and R2 with metal ions have been determined as 2:1 by using Job's plot. The colorimetric receptors exhibited high sensitivity with a low detection limit of ?M levels. In the presence of metal ions both receptors shows fluorescence quenching. This might be due to the photo induced electron transfer mechanism. The quenching constant was further determined using Stern-Volmer plot.

  2. Oxidation of benzoin catalyzed by oxovanadium(IV) schiff base complexes

    PubMed Central

    2013-01-01

    Background The oxidative transformation of benzoin to benzil has been accomplished by the use of a wide variety of reagents or catalysts and different reaction procedures. The conventional oxidizing agents yielded mainly benzaldehyde or/and benzoic acid and only a trace amount of benzil. The limits of practical utilization of these reagents involves the use of stoichiometric amounts of corrosive acids or toxic metallic reagents, which in turn produce undesirable waste materials and required high reaction temperatures. In recent years, vanadium complexes have attracted much attention for their potential utility as catalysts for various types of reactions. Results Active and selective catalytic systems of new unsymmetrical oxovanadium(IV) Schiff base complexes for the oxidation of benzoin is reported. The Schiff base ligands are derived between 2-aminoethanol and 2-hydroxy-1-naphthaldehyde (H2L1) or 3-ethoxy salicylaldehyde (H2L3); and 2-aminophenol and 3-ethoxysalicylaldehyde (H2L2) or 2-hydroxy-1-naphthaldehyde (H2L4). The unsymmetrical Schiff bases behave as tridentate dibasic ONO donor ligands. Reaction of these Schiff base ligands with oxovanadyl sulphate afforded the mononuclear oxovanadium(IV) complexes (VIVOLx.H2O), which are characterized by various physico-chemical techniques. The catalytic oxidation activities of these complexes for benzoin were evaluated using H2O2 as an oxidant. The best reaction conditions are obtained by considering the effect of solvent, reaction time and temperature. Under the optimized reaction conditions, VOL4 catalyst showed high conversion (>99%) with excellent selectivity to benzil (~100%) in a shorter reaction time compared to the other catalysts considered. Conclusion Four tridentate ONO type Schiff base ligands were synthesized. Complexation of these ligands with vanadyl(IV) sulphate leads to the formation of new oxovanadium(IV) complexes of type VIVOL.H2O. Elemental analyses and spectral data of the free ligands and their oxovanadium(IV) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. Oxovanadium complexes were screened for the oxidation of benzoin to benzil using H2O2 as oxidant. The effect of time, solvent and temperature were optimized to obtain maximum yield. The catalytic activity results demonstrate that these catalytic systems are both highly active and selective for the oxidation of benzoin under mild reaction conditions. PMID:23294561

  3. Synthesis and antioxidant activity of thymol and carvacrol based Schiff bases.

    PubMed

    Beena; Kumar, Deepak; Rawat, Diwan S

    2013-02-01

    Thymol and carvacrol are well known antioxidants found in the extract of the plants of thyme species. The Schiff bases of 2-iso-propyl-5-methyl-phenol (thymol/1a), 2-tert-butyl-5-methyl-phenol (1b) and 5-iso-propyl-2-methyl-phenol (carvacrol/1c) exhibited much better antioxidant activity than thymol and carvacrol in DPPH assay. Ten compounds (4k, 4l, 4r, 5k, 5l, 5q, 5r, 6k, 6l and 6r) showed better or similar activity as compared to the reference compound ascorbic acid. Twenty-four most active compounds were also screened by ABTS method and showed 60-90% inhibition at 5 ?g/mL concentration. PMID:23273412

  4. Synthesis, characterization and crystal structures of the bidentate Schiff base N,N'-bis(2-nitrocinnamaldehyde)ethylenediamine and its complex with CuNCS and triphenylphosphane.

    PubMed

    Clegg, William; Harrington, Ross W; Barati, Kazem; Habibi, Mohammad Hossein; Montazerozohori, Morteza; Lalegani, Arash

    2015-07-01

    Reaction of copper(I) thiocyanate and triphenylphosphane with the bidentate Schiff base N,N'-bis(trans-2-nitrocinnamaldehyde)ethylenediamine {Nca2en, (1); systematic name (1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]}, C20H18N4O4, in a 1:1:1 molar ratio in acetonitrile resulted in the formation of the complex {(1E,1'E,2E,2'E)-N,N'-(ethane-1,2-diyl)bis[3-(2-nitrophenyl)prop-2-en-1-imine]-?(2)N,N'}(thiocyanato-?N)(triphenylphosphane-?P)copper(I)], [Cu(NCS)(C20H18N4O4)(C18H15P)] or [Cu(NCS)(Nca2en)(PPh3)], (2). The Schiff base and copper(I) complex have been characterized by elemental analyses, IR, electronic and (1)H NMR spectroscopy, and X-ray crystallography [from synchrotron data for (1)]. The molecule of (1) lies on a crystallographic inversion centre, with a trans conformation for the ethylenediamine unit, and displays significant twists from coplanarity of its nitro group, aromatic ring, conjugated chain and especially ethylenediamine segments. It acts as a bidentate ligand coordinating via the imine N atoms to the Cu(I) atom in complex (2), in which the ethylenediamine unit necessarily adopts a somewhat flattened gauche conformation, resulting in a rather bowed shape overall for the ligand. The NCS(-) ligand is coordinated through its N atom. The geometry around the Cu(I) atom is distorted tetrahedral, with a small N-Cu-N bite angle of 81.56?(12) and an enlarged opposite angle of 117.29?(9) for SCN-Cu-P. Comparisons are made with the analogous Schiff base having no nitro substituents and with metal complexes of both ligands. PMID:26146396

  5. Crystal structure characterization as well as theoretical study of spectroscopic properties of novel Schiff bases containing pyrazole group

    NASA Astrophysics Data System (ADS)

    Guo, Jia; Ren, Tiegang; Zhang, Jinglai; Li, Guihui; Li, Weijie; Yang, Lirong

    2012-09-01

    A series of novel Schiff bases containing pyrazole group were synthesized using 1-aryl-3-methyl-4-benzoyl-5-pyrazolone and phenylenediamine as the starting materials. All as-synthesized Schiff bases were characterized by means of NMR, FT-IR, and MS; and the molecular geometries of two Schiff bases as typical examples were determined by means of single crystal X-ray diffraction. In the meantime, the ultraviolet-visible light absorption spectra and fluorescent spectra of various as-synthesized products were also measured. Moreover, the B3LYP/6-1G(d,p) method was used for the optimization of the ground state geometry of the Schiff bases; and the spectroscopic properties of the products were computed and compared with corresponding experimental data based on cc-pVTZ basis set of TD-B3LYP method. It has been found that all as-synthesized Schiff bases show a remarkable absorption peak in a wavelength range of 270-370 nm; and their maximum emission peaks are around 344 nm and 332 nm, respectively.

  6. Design, synthesis, and antibacterial activity of novel Schiff base derivatives of quinazolin-4(3H)-one.

    PubMed

    Wang, Xiang; Yin, Juan; Shi, Li; Zhang, Guoping; Song, Baoan

    2014-04-22

    Novel imine derivatives of quinazolin-4(3H)-one were designed and synthesized by using aminoethyl moieties to increase the amine bridge of quinazolin-4(3H)-one amine and then introducing various aromatic aldehydes. The target compounds were characterized by proton nuclear magnetic resonance spectroscopy ((1)H NMR), carbon nuclear magnetic resonance spectroscopy ((13)C NMR), mass spectrometry (MS), infrared spectroscopy (IR), elemental analysis, and X-ray diffraction crystallography. Bioassay results indicated that some of the compounds showed good to excellent antibacterial activities against tobacco bacterial wilt and tomato bacterial wilt. The 50% effective concentrations (EC50) of the compounds against tobacco and tomato bacterial wilts ranged from 63.73?g/mL to 201.52?g/mL and 38.64?g/mL to 81.39?g/mL, respectively, which are lower than that the positive control thiodiazole copper (216.70 and 99.80?g/mL). These results indicated that novel Schiff base derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco and tomato bacterial wilts. PMID:24607590

  7. Synthesis, spectral, antimicrobial and antitumor assessment of Schiff base derived from 2-aminobenzothiazole and its transition metal complexes

    NASA Astrophysics Data System (ADS)

    Etaiw, Safaa Eldin H.; Abd El-Aziz, Dina M.; Abd El-Zaher, Eman H.; Ali, Elham A.

    2011-09-01

    N-(thiophen-2-ylmethylene)benzo[ d]thiazol-2-amine Schiff base (L) derived from 2-aminobenzothiazole and 2-thiophenecarboxaldehyde was synthesized and characterized using elemental analysis, IR, mass spectra, 1H NMR and UV-vis spectra. Its complexes with Cu(II), Fe(III), Ni(II) and Zn(II) were prepared and isolated as solid products and characterized by elemental and thermal analyses, spectral techniques as well as magnetic susceptibility. The IR spectra showed that the Schiff base under investigation behaves as bidentate ligand. The UV-vis spectra and magnetic moment data suggested octahedral geometry around Cu(II) and Fe(III) and tetrahedral geometry around Ni(II) and Zn(II). In view of the biological activity of the Schiff base and its complexes, it has been observed that the antimicrobial activity of the Schiff base increased on complexation with the metal ion. In vitro antitumor activity assayed against five human tumor cell lines furnished the significant toxicities of the Schiff base and its complexes.

  8. Fluorescence of the Schiff bases of pyridoxal and pyridoxal 5'-phosphate withL-isoleucine in aqueous solutions.

    PubMed

    Cambrn, G; Sevilla, J M; Pineda, T; Blzquez, M

    1996-03-01

    The present study reports on the absorption and emission properties of the Schiff bases formed by pyridoxal and pyridoxal 5'-phosphate withL-isoleucine in aqueous solutions. Species protonated at the imine and ring nitrogen are the most fluorescent in both Schiff bases with a quantum yield of 0.02, i.e., 20-fold the value found for species in alkaline solutions. In agreement with other studies, species protonated at the imine nitrogen shows an emission around 500 nm upon excitation at 415 nm. In contrast to previous observations on other PLP Schiff bases, emissions at 560 nm (PL-Ile) and 540 nm (PLP-Ile) are observed upon excitation at 365 and 415 nm, respectively. The emission at 470 nm found in PLP-Ile Schiff base upon excitation at 355 nm is ascribed to a multipolar monoprotonated species. An estimation for the pK a of the imine in the excited state ( ? 8.5) for both Schiff bases is also reached. Our results suggest that fast protonation reactions on the excited state are responsible for the observed fluorescence. These effects, in which the hydrogen bond and the phosphate group seem to play a role, could be extended to understanding coenzyme environments in proteins. PMID:24226991

  9. Biological and Spectral Studies of Newly Synthesized Triazole Schiff Bases and Their Si(IV), Sn(IV) Complexes

    PubMed Central

    Singh, Kiran; Puri, Parvesh; Kumar, Yogender; Sharma, Chetan; Aneja, Kamal Rai

    2011-01-01

    The Schiff bases HL1-3 have been prepared by the reaction of 5-bromothiophene-2-carboxaldehyde with 4-amino-5-mercapto-3-methyl/propyl/isopropyl-s-triazole, respectively. Organosilicon(IV) and organotin(IV) complexes of formulae (CH3)2MCl(L1-3), (CH3)2M(L1-3)2 were synthesized from the reaction of (CH3)2MCl2 and the Schiff bases in 1?:?1 and 1?:?2 molar ratio, where M = Si and Sn. The synthesized Schiff bases and their metal complexes have been characterized with the aid of various physicochemical techniques like elemental analyses, molar conductance, UV, IR, 1H, 13C, 29Si, and 119Sn NMR spectroscopy. Based on these studies, the trigonal bipyramidal and octahedral geometries have been proposed for these complexes. The ligands and their metal complexes have been screened in vitro against some bacteria and fungi. PMID:21826133

  10. Synthesis and characterization of chromium(III) Schiff base complexes: Antimicrobial activity and its electrocatalytic sensing ability of catechol

    NASA Astrophysics Data System (ADS)

    Praveen Kumar, S.; Suresh, R.; Giribabu, K.; Manigandan, R.; Munusamy, S.; Muthamizh, S.; Narayanan, V.

    2015-03-01

    A series of acyclic Schiff base chromium(III) complexes were synthesized with the aid of microwave irradiation method. The complexes were characterized on the basis of elemental analysis, spectral analysis such as UV-Visible, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) spectroscopies and electrospray ionization (ESI) mass spectrometry. Electrochemical analysis of the complexes indicates the presence of chromium ion in +3 oxidation state. Cr (III) ion is stabilized by the tetradentate Schiff base ligand through its nitrogen and phenolic oxygen. From the spectral studies it is understood that the synthesized chromium(III) complexes exhibits octahedral geometry. Antimicrobial activity of chromium complexes was investigated towards the Gram positive and Gram negative bacteria. In the present work, an attempt was made to fabricate a new kind of modified electrode based on chromium Schiff base complexes for the detection of catechol at nanomolar level.

  11. Biological and Spectral Studies of Newly Synthesized Triazole Schiff Bases and Their Si(IV), Sn(IV) Complexes.

    PubMed

    Singh, Kiran; Puri, Parvesh; Kumar, Yogender; Sharma, Chetan; Aneja, Kamal Rai

    2011-01-01

    The Schiff bases HL(1-3) have been prepared by the reaction of 5-bromothiophene-2-carboxaldehyde with 4-amino-5-mercapto-3-methyl/propyl/isopropyl-s-triazole, respectively. Organosilicon(IV) and organotin(IV) complexes of formulae (CH(3))(2)MCl(L(1-3)), (CH(3))(2)M(L(1-3))(2) were synthesized from the reaction of (CH(3))(2)MCl(2) and the Schiff bases in 1?:?1 and 1?:?2 molar ratio, where M = Si and Sn. The synthesized Schiff bases and their metal complexes have been characterized with the aid of various physicochemical techniques like elemental analyses, molar conductance, UV, IR, (1)H, (13)C, (29)Si, and (119)Sn NMR spectroscopy. Based on these studies, the trigonal bipyramidal and octahedral geometries have been proposed for these complexes. The ligands and their metal complexes have been screened in vitro against some bacteria and fungi. PMID:21826133

  12. Schiff bases of indoline-2,3-dione (isatin) with potential antiproliferative activity

    PubMed Central

    2012-01-01

    Background Cancer is one of the most dreaded diseases and it is a leading cause of mankind death worldwide. Recent reports documented a remarkable antiproliferative activity of isatin nucleus against various cancer cell lines. The current work describes the antiproliferative activity of Schiff bases of combinatorial mixtures of the isatin derivatives M1-M22 as well as the individual compounds 1-11(A-K) of these combinatorial mixtures. Results The designed combinatorial library composed from eleven hydrazides A-K and eleven isatin derivatives 1-11 has been synthesized to formally generate 22 mixtures, M1-M22 of 121 Schiff bases, and their antiproliferative activity against K562 chronic myelogenous leukemia cells was evaluated. The indexed method of analysis of the prepared library was applied to elucidate the active components in the tested mixtures M1-M22. The predictions from the crossing procedure was validated through evaluation of the antiproliferative activity of individual compounds 1-11(A-K) of the library. Individual compounds 1-11(A-K) were also evaluated against the non-tumorigenic MCF-12A cell line to investigate their selectivity. A pharmacophore model was developed to further optimize the antiproliferative activity among this series of compounds. Conclusions Variable antiproliferative activity was revealed with the investigated mixtures M1-M22 and the individual compounds 1-11(A-K). Most of the tested mixtures and several individual Schiff bases displayed high potency with IC50 values in the low micromolar range. A considerable selectivity of some individual compounds to the tumorigenic K562 cell line compared with the non-tumorigenic MCF-12A cell line was observed as indicated by their selectivity index (SI). PMID:22647272

  13. A novel coumarin Schiff-base as a Ni(II) ion colorimetric sensor

    NASA Astrophysics Data System (ADS)

    Wang, Lingyun; Ye, Decheng; Cao, Derong

    2012-05-01

    A novel coumarin Schiff base compound (L) prepared from 7-diethylaminocoumarin-3-aldehyde and 3-amino-7-hydroxycoumarin was synthesized and evaluated as a chemoselective Ni2+ sensor. Addition of Ni2+ to CH3CN solution of L resulted in a rapid color change from yellow to red together with a large red shift from 465 to 516 nm. Moreover, other common alkali-, alkaline earth-, transition- and rare earth metal ions induced no or minimal spectral changes. Experimental results indicated that L could be used as a potential Ni2+ colorimetric and naked-eye chemosensor in CH3CN solution.

  14. A new thio-Schiff base fluorophore with copper ion sensing, DNA binding and nuclease activity.

    PubMed

    Vikneswaran, R; Syafiq, Muhamad Syamir; Eltayeb, Naser Eltaher; Kamaruddin, Mohd Naqiuddin; Ramesh, S; Yahya, R

    2015-11-01

    Copper ion recognition and DNA interaction of a newly synthesized fluorescent Schiff base (HPyETSC) were investigated using UV-vis and fluorescent spectroscopy. Examination using these two techniques revealed that the detection of copper by HPyETSC is highly sensitive and selective, with a detection limit of 0.39 ?m and the mode of interaction between HPyETSC and DNA is electrostatic, with a binding constant of 8.9710(4) M(-1). Furthermore, gel electrophoresis studies showed that HPyETSC exhibited nuclease activity through oxidative pathway. PMID:26046495

  15. Copper(II) complexes of coumarin-derived Schiff bases and their anti-Candida activity.

    PubMed

    Creaven, Bernadette S; Devereux, Michael; Karcz, Dariusz; Kellett, Andrew; McCann, Malachy; Noble, Andy; Walsh, Maureen

    2009-09-01

    The condensation of 7-amino-4-methyl-coumarin (1) with a number of substituted salicylaldehydes yielded a series of Schiff bases (2a-2k) in good yields. Subsequent reaction of these ligands with copper(II) acetate yielded Cu(II) complexes (3a-3k) and some were characterised using X-ray crystallography. All of the free ligands and their metal complexes were tested for their anti-Candida activity. A number of the ligands and complexes exhibited anti-Candida activity comparable to that of the commercially available antifungal drugs, ketoconazole and Amphotericin B. PMID:19631386

  16. Synthesis and electrochromic, acidochromic properties of Schiff bases containing triphenylamine and thiophene units

    NASA Astrophysics Data System (ADS)

    Wu, Xiaotong; Wang, Wen; Li, Bin; Hou, Yanjun; Niu, Haijun; Zhang, Yanhong; Wang, Shuhong; Bai, Xuduo

    2015-04-01

    A series of Schiff bases (SBs) were designed and prepared from 2-thiophenecarboxaldehyde and different triphenylamine (TPA) derivatives. The structures of the compounds were characterized by Fourier transform infrared (FT-IR), hydrogen nuclear magnetic resonance (1H NMR). The optical and electrochemical properties were tested by ultraviolet-visible (UV-vis) spectroscopy and cyclic voltammetry (CV) techniques. The SBs exhibited stable and reversible electrochromic properties. Furthermore, multiple reversible colors states were also observed with the change of pH. Consequently, the SBs can be used as electrochromic and acidochromic materials.

  17. Encapsulation of chromen-4-one Schiff's bases by C-Hexylpyrogallol[4]arene and its structure

    NASA Astrophysics Data System (ADS)

    Chandrasekaran, Sowrirajan; Enoch, Israel V. M. V.

    2015-12-01

    In this paper, we report the encapsulation of Chromen-4-one Schiff's base derivatives with the host molecule C-Hexylpyrogallol[4]arene. The stoichiometry, binding constant, and the mode of association of the guest molecules with C-Hexylpyrogallol[4]arene are investigated by ultraviolet-visible absorption, steady-state and time-resolved fluorescence, and two dimensional Rotating-frame nuclear Overhauser spectroscopic techniques. The stoichiometry of the host-guest complexes is 1:2. The binding constants of the complexes are of the order of 104. The structures of the host-guest complexes are proposed.

  18. XAFS study of metal chelates of phenylazo derivatives of Schiff bases

    NASA Astrophysics Data System (ADS)

    Burlov, Anatolii S.; Mashchenko, Sergey A.; Vlasenko, Valery G.; Zubavichus, Yan V.; Uraev, Ali I.; Lyssenko, Konstantin A.; Levchenkov, Sergei I.; Vasilchenko, Igor S.; Garnovskii, Dmitrii A.; Borodkin, Gennadii S.

    2014-03-01

    The Schiff base derived from o-tosylaminobenzaldehyde and p-aminoazobenzene and its metal chelates (Co2+, Ni2+, Cu2+, and Zn2+) have been synthesized and investigated (IR, 1H NMR, XANES, EXAFS spectroscopy, X-ray diffraction, magnetic measurements). It was found that the azomethine exists in the amino-imine tautomeric form both in solutions and solid state. XAFS investigations reveal that the complexes adopt either distorted tetrahedral or octahedral (due to additional coordination of oxygen atoms of the tosylamino group) ligand environment.

  19. Synthesis and electrochromic, acidochromic properties of Schiff bases containing triphenylamine and thiophene units.

    PubMed

    Wu, Xiaotong; Wang, Wen; Li, Bin; Hou, Yanjun; Niu, Haijun; Zhang, Yanhong; Wang, Shuhong; Bai, Xuduo

    2015-04-01

    A series of Schiff bases (SBs) were designed and prepared from 2-thiophenecarboxaldehyde and different triphenylamine (TPA) derivatives. The structures of the compounds were characterized by Fourier transform infrared (FT-IR), hydrogen nuclear magnetic resonance (1H NMR). The optical and electrochemical properties were tested by ultraviolet-visible (UV-vis) spectroscopy and cyclic voltammetry (CV) techniques. The SBs exhibited stable and reversible electrochromic properties. Furthermore, multiple reversible colors states were also observed with the change of pH. Consequently, the SBs can be used as electrochromic and acidochromic materials. PMID:25617980

  20. Synthesis and characterization of copper complexes of Schiff base derived from isatin and salicylic hydrazide

    SciTech Connect

    Lekshmy, R. K. E-mail: tharapradeepkumar@yahoo.com; Thara, G. S. E-mail: tharapradeepkumar@yahoo.com

    2014-10-15

    A series of novel metal complexes of Schiff base have been prepared by the interaction of Cu(II) with isatin salicylic hydrazide. All the new compounds were characterized by elemental analysis, conductance measurement, magnetic moment determination, IR, UV, NMR, Mass and EPR spectral studies, thermal studies and microbial activities. The results indicate that the ligand acts as a tridentate chelating ligand coordinating through nitrogen and oxygen atoms. The ligand and complexes show inactive against Escherichia coli and active against Staphylococcus aureus and B.substilis. By analyzing the results of spectral, thermal and elemental analysis square planar geometry is proposed for all the complexes.

  1. Synthesis, characterization and antibacterial activity of a tridentate Schiff base derived from cephalothin and sulfadiazine, and its transition metal complexes.

    PubMed

    Anacona, J R; Noriega, Natiana; Camus, Juan

    2015-02-25

    Metal(II) coordination compounds of a cephalothin Schiff base (H2L) derived from the condensation of cephalothin antibiotic with sulfadiazine were synthesized. The Schiff base ligand, mononuclear [ML(H2O)3] (M(II)=Mn,Co,Ni,Zn) complexes and magnetically diluted dinuclear copper(II) complex [CuL(H2O)3]2 were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The cephalothin Schiff base ligand H2L behaves as a dianionic tridentate NOO chelating agent. The biological applications of complexes have been studied on two bacteria strains (Escherichia coli and Staphylococcus aureus) by agar diffusion disc method. PMID:25194315

  2. An electrochemical procedure coupled with a Schiff base method; application to electroorganic synthesis of new nitrogen-containing heterocycles

    SciTech Connect

    Dowlati, Bahram; Othman, Mohamed Rozali

    2013-11-27

    The synthesis of Nitrogen-containing heterocycles has been achieved using chemical and electrochemical methods, respectively. The direct chemical synthesis of nucleophiles proceeds through the Schiff base chemical reaction. This procedure offers an alternate reaction between dicarbonyl compounds and diamines leads to the formation of products. The results indicate that the Schiff base chemical method for synthesis of the product has successfully performed in excellent overall yield. In the electrochemical step, a series of Nitrogen-containing compounds were electrosynthesized. Various parameters such as the applied potential, pH of the electrolytic solution, cell configuration and also purification techniques, were carried out to optimize the yields of corresponding products. New Nitrogen-containing heterocycle derivatives were synthesized using an electrochemical procedure coupled with a Schiff base as a facile, efficient and practical method. The products have been characterized after purification by IR, {sup 1}H NMR, {sup 13}C NMR and ESI-MS{sup 2}.

  3. Synthesis, characterization and antibacterial activity of a tridentate Schiff base derived from cephalothin and sulfadiazine, and its transition metal complexes

    NASA Astrophysics Data System (ADS)

    Anacona, J. R.; Noriega, Natiana; Camus, Juan

    2015-02-01

    Metal(II) coordination compounds of a cephalothin Schiff base (H2L) derived from the condensation of cephalothin antibiotic with sulfadiazine were synthesized. The Schiff base ligand, mononuclear [ML(H2O)3] (M(II) = Mn, Co, Ni, Zn) complexes and magnetically diluted dinuclear copper(II) complex [CuL(H2O)3]2 were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and 1H NMR spectral studies. The cephalothin Schiff base ligand H2L behaves as a dianionic tridentate NOO chelating agent. The biological applications of complexes have been studied on two bacteria strains (Escherichia coli and Staphylococcus aureus) by agar diffusion disc method.

  4. An electrochemical procedure coupled with a Schiff base method; application to electroorganic synthesis of new nitrogen-containing heterocycles

    NASA Astrophysics Data System (ADS)

    Dowlati, Bahram; Othman, Mohamed Rozali

    2013-11-01

    The synthesis of Nitrogen-containing heterocycles has been achieved using chemical and electrochemical methods, respectively. The direct chemical synthesis of nucleophiles proceeds through the Schiff base chemical reaction. This procedure offers an alternate reaction between dicarbonyl compounds and diamines leads to the formation of products. The results indicate that the Schiff base chemical method for synthesis of the product has successfully performed in excellent overall yield. In the electrochemical step, a series of Nitrogen-containing compounds were electrosynthesized. Various parameters such as the applied potential, pH of the electrolytic solution, cell configuration and also purification techniques, were carried out to optimize the yields of corresponding products. New Nitrogen-containing heterocycle derivatives were synthesized using an electrochemical procedure coupled with a Schiff base as a facile, efficient and practical method. The products have been characterized after purification by IR, 1H NMR, 13C NMR and ESI-MS2.

  5. Synthetic, Structural, and Biochemical Studies of Organotin(IV) With Schiff Bases Having Nitrogen and Sulphur Donor Ligands

    PubMed Central

    Singh, Har Lal; Varshney, A. K.

    2006-01-01

    Three bidentate Schiff bases having nitrogen and sulphur donor sequences were prepared by condensing S-benzyldithiocarbazate (NH2NHCS2CH2C6H5) with heterocyclic aldehydes. The reaction of diphenyltin dichloride with Schiff bases leads to the formation of a new series of organotin(IV) complexes. An attempt has been made to prove their structures on the basis of elemental analyses, conductance measurements, molecular weights determinations, UV, infrared, and multinuclear magnetic resonance (1H, 13C, and 119Sn) spectral studies. Organotin(IV) complexes were five- and six-coordinate. Schiff bases and their corresponding organotin complexes have also been screened for their antibacterial and antifungal activities and found to be quite active in this respect. PMID:17497003

  6. Synthesis, characterization and antibacterial activity of a Schiff base derived from cephalexin and sulphathiazole and its transition metal complexes

    NASA Astrophysics Data System (ADS)

    Anacona, J. R.; Rodriguez, Juan Luis; Camus, Juan

    2014-08-01

    Metal(II) coordination compounds of a cephalexin Schiff base (HL) derived from the condensation of cephalexin antibiotic with sulphathiazole were synthesized. The Schiff base ligand, mononuclear [ML(OAc)(H2O)2] (M(II) = Mn, Co, Ni, Zn) complexes and magnetically diluted trinuclear copper(II) complex [Cu3L(OH)5] were characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and 1H NMR spectral studies. The analytical and molar conductance values indicated that the acetate ions coordinate to the metal ions. The Schiff base ligand HL behaves as a monoanionic tridentate NNO and tetradentate NNOO chelating agent in the mono and trinuclear complexes respectively.

  7. Convergence of Schiff base costimulatory signaling and TCR signaling at the level of mitogen-activated protein kinase ERK2.

    PubMed

    Chen, H; Hall, S; Heffernan, B; Thompson, N T; Rogers, M V; Rhodes, J

    1997-09-01

    Schiff base formation on specialized T cell surface amines provides a costimulatory signal to T cells through a mechanism that activates Na+ and K+ transport, substantially enhancing TCR-dependent IL-2 production. Schiff base-forming molecules that mimic the natural carbonyl donor potently enhance immune responses and provide the first mechanism-based, orally active immunopotentiatory agents. In the present study, costimulation by the Schiff base-forming molecule tucaresol was investigated at the level of mitogen-activated protein kinase (MAPK) in T cell lines. Both TCR-directed stimulation by anti-CD3 and Schiff base stimulation by tucaresol produced a distinct mobility shift in MAPK, characterized by direct immunoblotting of cell lysate proteins subjected to SDS-PAGE, that corresponded with increased phosphorylation. Combined TCR-CD3 and tucaresol stimulation substantially enhanced and prolonged the MAPK response, providing a biochemical basis for the costimulatory nature of the pathway utilized by Schiff base signaling. The MAPK affected was identified by immunoprecipitation as ERK2. Both the direct effects and the TCR signal-enhancing effects of tucaresol on MAPK activation were also demonstrated in a functional MAPK assay measuring substrate phosphorylation. Borohydride reduction of tucaresol's Schiff base-forming carbonyl group abolished both enhancement of MAPK phosphorylation and IL-2 production, as did a selective inhibitor of the MAPKK, MEK1. Tucaresol had no effect on TCR-mediated rises in intracellular free Ca2+ or inositol 1,4,5-triphosphate generation, while tucaresol signaling occurred normally in the lck-deficient J.CaM1.6 T cell line, consistent with convergence of tucaresol- and TCR-induced signals downstream of early TCR-mediated events. PMID:9278316

  8. Synthesis, interaction with DNA and antiproliferative activities of two novel Cu(II) complexes with Schiff base of benzimidazole.

    PubMed

    Song, Wen-Ji; Cheng, Jian-Ping; Jiang, Dong-Hua; Guo, Li; Cai, Meng-Fei; Yang, Hu-Bin; Lin, Qiu-Yue

    2014-01-01

    Two novel copper(II) complexes with Schiff base of benzimidazole [Cu(L)Cl]2CH3OH have been synthesized. HL(1) (N-(benzimidazol-2-ymethyl)-5-chlorosalicylideneimine, C15H11ClN3O) and HL(2) (N-(benzimidazol-2-ymethyl)-salicylideneimine, C15H12N3O) are ligands of complex (1) and complex (2), respectively. The complexes were characterized by elemental analysis, IR, UV-Vis, TGA and X-ray diffraction. Within the complexes, Cu(II) ions were four coordinated by two nitrogen atom of azomethine and imine, one phenolic oxygen atom from HL and one chloride atom. A distorted quadrilateral structure was formed. Complex (1) crystallized in the triclinic crystal system. Results showed that ?-? stacking effect occurred due to the existence of aromatic ring from Schiff base and hydrogen bonding between methanol and adjacent atoms. The DNA binding properties of the complexes were investigated by electronic absorption spectra, fluorescence spectra and viscosity measurements. Results indicated that complexes bound to DNA via partial intercalation mode. The DNA binding constants Kb/(L mol(-1)) were 1.8110(4) (1), 1.3710(4) (2), 6.2710(3) (HL(1)) and 3.1410(3) (HL(2)) at 298 K. The title complexes could quench the emission intensities of EB-DNA system significantly. The results of agarose gel electrophoresis indicated complex (1) could cleave supercoiled DNA through the oxidative mechanism. The inhibition ratios revealed that complex (1) and HL(1) had strong antiproliferative activities against human breast cancer cells (MCF-7) lines and human colorectal cancer cells (COLO205) lines in vitro. The antiproliferative activities of complex (1) against MCF-7 lines (IC50=16.91.5 ?mol L(-1)) and against COLO205 lines (IC50=16.53.4 ?mol L(-1)) is much stronger than that of HL(1), which had the potential to develop anti-cancer drug. PMID:24220672

  9. Suppression of the back proton-transfer from Asp85 to the retinal Schiff base in bacteriorhodopsin: A theoretical analysis of structural elements.

    SciTech Connect

    Bondar, A.N.; Suhai, Sandor; Fischer, S.; Smith, Jeremy C; Elstner, Marcus

    2007-03-01

    The transfer of a proton from the retinal Schiff base to the nearby Asp85 protein group is an essential step in the directional proton-pumping by bacteriorhodopsin. To avoid the wasteful back reprotonation of the Schiff base from Asp85, the protein must ensure that, following Schiff base deprotonation, the energy barrier for back proton-transfer from Asp85 to the Schiff base is larger than that for proton-transfer from the Schiff base to Asp85. Here, three structural elements that may contribute to suppressing the back proton-transfer from Asp85 to the Schiff base are investigated: (1) retinal twisting; (2) hydrogen-bonding distances in the active site; and (3) the number and location of internal water molecules. The impact of the pattern of bond twisting on the retinal deprotonation energy is dissected by performing an extensive set of quantum-mechanical calculations. Structural rearrangements in the active site, such as changes of the Thr89:Asp85 distance and relocation of water molecules hydrogen-bonding to the Asp85 acceptor group, may participate in the mechanism which ensures that following the transfer of the Schiff base proton to Asp85 the protein proceeds with the subsequent photocycle steps, and not with back proton transfer from Asp85 to the Schiff base.

  10. Suppression of the back proton-transfer from Asp85 to the retinal Schiff base in bacteriorhodopsin: A theoretical analysis of structural elements

    SciTech Connect

    Bondar, A.N.; Suhai, Sandor; Fischer, S.; Smith, Jeremy C; Elstner, Marcus

    2007-03-01

    The transfer of a proton from the retinal Schiff base to the nearby Asp85 protein group is an essential step in the directional proton-pumping by bacteriorhodopsin. To avoid the wasteful back reprotonation of the Schiff base from Asp85, the protein must ensure that, following Schiff base deprotonation, the energy barrier for back proton-transfer from Asp85 to the Schiff base is larger than that for proton-transfer from the Schiff base to Asp85. Here, three structural elements that may contribute to suppressing the back proton-transfer from Asp85 to the Schiff base are investigated: (i) retinal twisting; (ii) hydrogen-bonding distances in the active site; and (iii) the number and location of internal water molecules. The impact of the pattern of bond twisting on the retinal deprotonation energy is dissected by performing an extensive set of quantum-mechanical calculations. Structural rearrangements in the active site, such as changes of the Thr89:Asp85 distance and relocation of water molecules hydrogen-bonding to the Asp85 acceptor group, may participate in the mechanism which ensures that following the transfer of the Schiff base proton to Asp85 the protein proceeds with the subsequent photocycle steps, and not with back proton transfer from Asp85 to the Schiff base.

  11. Suppression of the back proton-transfer from Asp85 to the retinal Schiff base in bacteriorhodopsin: A theoretical analysis of structural elements

    SciTech Connect

    Bondar, A.N.; Suhai, Sandor; Fischer, S.; Smith, Jeremy C; Elstner, Marcus

    2006-10-01

    The transfer of a proton from the retinal Schiff base to the nearby Asp85 protein group is an essential step in the directional proton-pumping by bacteriorhodopsin. To avoid the wasteful back reprotonation of the Schiff base from Asp85, the protein must ensure that, following Schiff base deprotonation, the energy barrier for back proton-transfer from Asp85 to the Schiff base is larger than that for proton-transfer from the Schiff base to Asp85. Here, three structural elements that may contribute to suppressing the back proton-transfer from Asp85 to the Schiff base are investigated: (1) retinal twisting; (2) hydrogen-bonding distances in the active site; and (3) the number and location of internal water molecules. The impact of the pattern of bond twisting on the retinal deprotonation energy is dissected by performing an extensive set of quantum-mechanical calculations. Structural rearrangements in the active site, such as changes of the Thr89:Asp85 distance and relocation of water molecules hydrogen-bonding to the Asp85 acceptor group, may participate in the mechanism which ensures that following the transfer of the Schiff base proton to Asp85 the protein proceeds with the subsequent photocycle steps, and not with back proton transfer from Asp85 to the Schiff base.

  12. Estimated acid dissociation constants of the Schiff base, Asp-85, and Arg-82 during the bacteriorhodopsin photocycle.

    PubMed Central

    Brown, L S; Bonet, L; Needleman, R; Lanyi, J K

    1993-01-01

    The pK(a) values of D85 in the wild-type and R82Q, as well as R82A recombinant bacteriorhodopsins, and the Schiff base in the D85N, D85T, and D85N/R82Q proteins, have been determined by spectroscopic titrations in the dark. They are used to estimate the coulombic interaction energies and the pK(a) values of the Schiff base, D85, and R82 during proton transfer from the Schiff base to D85, and the subsequent proton release to the bulk in the initial part of the photocycle. The pK(a) of the Schiff base before photoexcitation is calculated to be in effect only 5.3-5.7 pH units higher than that of D85; overcoming this to allow proton transfer to D85 requires about two thirds of the estimated excess free energy retained after absorption of a photon. The proton release on the extracellular surface is from an unidentified residue whose pK(a) is lowered to about 6 after deprotonation of the Schiff base (Zimanyi, L., G. Varo, M. Chang, B. Ni, R. Needleman, and J.K. Lanyi, 1992. Biochemistry. 31:8535-8543). We calculate that the pK(a) of the R82 is 13.8 before photoexcitation, and it is lowered after proton exchange between the Schiff base and D85 only by 1.5-2.3 pH units. Therefore, coulombic interactions alone do not appear to change the pK(a) of R82 as much and D85 only by 1.5-2.3 pH units. Therefore, coulombic interactions alone do not appear to change the pK(a) of R82 as much as required if it were the proton release group. PMID:8369421

  13. Fluorescent "turn-on" detecting CN- by nucleophilic addition induced Schiff-base hydrolysis

    NASA Astrophysics Data System (ADS)

    Lin, Qi; Cai, Yi; Li, Qiao; Shi, Bing-Bing; Yao, Hong; Zhang, You-Ming; Wei, Tai-Bao

    2015-04-01

    A new chemosensor Sz based on Schiff-base group as recognition site and naphthalene as the fluorescence signal group was designed and synthesised. It could fluorescent "turn-on" detect cyanide (CN-) via a novel mechanism of nucleophilic addition induced Schiff-base hydrolysis. Adding the CN- into the solution of Sz could induce Sz to emit blue fluorescence at 435 nm instantly. Moreover, Sz could also colorimetric detect CN-. Upon the addition of CN-, the Sz showed dramatic color change from yellow to colorless. These sensing procedures could not be interfered by other coexistent competitive anions such as F-, AcO-, H2PO4- and SCN-. In addition, Sz showed high sensitivity for CN-, the detection limits is 3.42 × 10-8 M of CN-, which is far lower than the WHO guideline of CN- in drinking water (less than 1.9 × 10-6 M). The CN- test strips based on Sz could act as a convenient CN- test kits.

  14. Fluorescent "turn-on" detecting CN(-) by nucleophilic addition induced Schiff-base hydrolysis.

    PubMed

    Lin, Qi; Cai, Yi; Li, Qiao; Shi, Bing-Bing; Yao, Hong; Zhang, You-Ming; Wei, Tai-Bao

    2015-04-15

    A new chemosensor Sz based on Schiff-base group as recognition site and naphthalene as the fluorescence signal group was designed and synthesised. It could fluorescent "turn-on" detect cyanide (CN(-)) via a novel mechanism of nucleophilic addition induced Schiff-base hydrolysis. Adding the CN(-) into the solution of Sz could induce Sz to emit blue fluorescence at 435 nm instantly. Moreover, Sz could also colorimetric detect CN(-). Upon the addition of CN(-), the Sz showed dramatic color change from yellow to colorless. These sensing procedures could not be interfered by other coexistent competitive anions such as F(-), AcO(-), H2PO4(-) and SCN(-). In addition, Sz showed high sensitivity for CN(-), the detection limits is 3.42×10(-8) M of CN(-), which is far lower than the WHO guideline of CN(-) in drinking water (less than 1.9×10(-6) M). The CN(-) test strips based on Sz could act as a convenient CN(-) test kits. PMID:25668691

  15. PM3 semi-empirical IR spectra simulations for metal complexes of schiff bases of sulfa drugs

    NASA Astrophysics Data System (ADS)

    Topacli, C.; Topacli, A.

    2003-06-01

    The molecular structures and infrared spectra of Co, Ni, Cu and Zn complexes of two schiff base ligands, viz N-( o-vanillinidene)sulfanilamide ( oVSaH) and N-( o-vanillinidene)sulfamerazine ( oVSmrzH) are studied in detail by PM3 method. It has been shown that the proposed structures for the compounds derived from microanalytical, magnetic and various spectral data were consistent with the IR spectra simulated by PM3 method. Coordination effects on ν(CN) and ν(C-O) modes in the schiff base ligands are in close agreement with the observed results.

  16. Structural and biological behaviors of some nonionic Schiff-base amphiphiles and their Cu(II) and Fe(III) metal complexes.

    PubMed

    Negm, Nabel A; Zaki, Mohamed F

    2008-07-15

    Novel series of nonionic Schiff bases was synthesized and characterized using microelemental analysis, FTIR and (1)H NMR spectra. These Schiff bases and their complexes with Cu and Fe have been evaluated for their antibacterial activity against bacterial species such as Staphylococcus aureus, Pseudomonas aureus, Candida albi, Bacillus subtilis and Escherichia coli and their fungicidal activity against Aspcrgillus niger and Aspcrgillus flavus. The results of the biocidal activities showed high potent action of the synthesized Schiff bases towards both bacteria and fungi. Furthermore, complexation of these Schiff bases by Cu(II) and Fe(III) show the metal complexes to be more antibacterial and antifungal than the Schiff bases. The results were correlated to the surface activity and the transition metal type. The mode of action of these complexes was discussed. PMID:18325743

  17. Synthesis, Characterization, and BSA Binding Studies of Some New Benzamides Related to Schiff Base

    PubMed Central

    Prashanth, M. K.; Madaiah, M.; Revanasiddappa, H. D.; Amruthesh, K. N.

    2013-01-01

    Condensation of amine 1 with aldehyde 2 gives Schiff base, N-(4-((benzofuran-2-ylmethylene) amino)phenyl)acetamide 3. Schiff base on N-acylation with different substituted acid chlorides in the presence of triethylamine gives the corresponding benzamides, N-acetyl-N-(4-((benzofuran-2-ylmethylene)amino)phenyl)substitutedbenzamide (NABP) 5a–j. The structures of newly synthesized compounds were characterized by elemental analysis, 1H NMR, 13C NMR FT-IR, and mass spectral studies. Compounds 3 and 5a–j have been screened for their antimicrobial activity using the disc diffusion and minimum inhibitory concentration (MIC) method against the selected bacterial and fungal strain. Compounds 5a, 5e, 5g, and 5h were found to be more active against all tested strains. The antioxidant properties were evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radical scavenging methods. Compounds 5i and 5j showed predominant antioxidant activities among the synthesized analogues. The interaction between NABP and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopic techniques at 298 K under imitated physiological conditions. The results revealed that NABP caused the fluorescence quenching of BSA through a static quenching procedure. The binding constants and the number of binding sites were calculated. The binding distance between the donor (BSA) and acceptor (NABP) was determined based on Forster's theory. PMID:24052869

  18. Synthesis and characterization of three novel Schiff base compounds: Experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Taslı, P. T.; Bayrakdar, A.; Karakus, O. O.; Kart, H. H.; Koc, Y.

    2015-09-01

    In this study, three novel Schiff base compounds such as N-(4-nitrobenzyl)-4-methyl bromo aniline ( 1a), N-(2,4-dimethoxybenzyl)-4-methyl bromoaniline ( 2a), SN-((1H-indol-3-yl) methylene)-4- methyl bromoaniline ( 3a) are synthesized and characterized by using the spectroscopic methods of UV, IR and 1H-NMR. Molecular geometry and spectroscopic properties of synthesized compounds are also analyzed by using ab initio calculation methods based on the density functional theory (DFT) in the ground state. The extensive theoretical and experimental FT-IR and UV-vis spectrometry studies of synthesized compounds are performed. The optimized molecular structure and harmonic vibrational frequencies are studied by using B3LYP/6-311++G(d,p) method. Moreover, electronic structures are investigated by using the time dependent density functional theory (TD-DFT) while the energy changes of the parent compounds are examined in a solvent medium by using the polarizable continuum model (PCM). Additionally, the frontier molecular orbital analysis is performed for the Schiff base compounds. The electronic properties of each compound such as; chemical hardness, chemical softness, ionization potential, electron affinity, electronegativity and chemical potential are investigated by utilizing the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies.

  19. New 3,4-diaminobenzoic acid Schiff base compounds and their complexes: Synthesis, characterization and thermodynamics

    NASA Astrophysics Data System (ADS)

    Mohammadi, Khosro; Niad, Mahmood; Jafari, Tahereh

    2014-03-01

    Some new tetradentate Schiff base ligands (H3L) were prepared via condensation of 3,4-diaminobenzoic acid with 2-hydroxybenzaldehyde derivatives, such as 3,4-bis((E)-2,4-dihydroxybenzylideneamino)benzoic acid (H3L1), 3,4-bis((E)-2-hydroxy-3-methoxybenzylideneamino)benzoic acid (H3L2) and 3,4-bis((E)-5-bromo-2-hydroxybenzylideneamino)benzoic acid (H3L4). Additionally, a tetradentate Schiff base ligand 3,4-bis((E)-2-hydroxybenzylideneamino)benzoic acid (H3L3) and its complexes were synthesized. Their metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) were prepared in good yields from the reaction of the ligands with the corresponding metal acetate. They were characterized based on IR, 1H NMR, Mass spectroscopy and UV-Vis spectroscopy. Also, the formation constants of the complexes were measured by UV-Vis spectroscopic titration at constant ionic strength 0.1 M (NaClO4), at 25 C in dimethylformamide (DMF) as a solvent.

  20. Metal-Based Biologically Active Compounds: Synthesis, Spectral, and Antimicrobial Studies of Cobalt, Nickel, Copper, and Zinc Complexes of Triazole-Derived Schiff Bases

    PubMed Central

    Singh, Kiran; Kumar, Yogender; Puri, Parvesh; Sharma, Chetan; Aneja, Kamal Rai

    2011-01-01

    A series of cobalt, nickel, copper, and zinc complexes of bidentate Schiff bases derived from the condensation reaction of 4-amino-5-mercapto-3-methyl/ethyl-1,2,4-triazole with 2,4-dichlorobenzaldehyde were synthesized and tested as antimicrobial agents. The synthesized Schiff bases and their metal complexes were characterized with the aid of elemental analyses, magnetic moment measurements, spectroscopic and thermogravimetric techniques. The presence of coordinated water in metal complexes was supported by infrared and thermal gravimetric studies. A square planar geometry was suggested for Cu(II) and octahedral geometry proposed for Co(II), Ni(II), and Zn(II) complexes. The Schiff bases and their metal complexes have been screened for antibacterial (Pseudomonas aeruginosa, Bacillus subtilis) and antifungal activities (Aspergillus niger, A. flavus). The metal complexes exhibited significantly enhanced antibacterial and antifungal activity as compared to their simple Schiff bases. PMID:22216017

  1. Syntheses, structures, and magnetic properties of homodinuclear lanthanide complexes based on dinucleating Schiff base ligands.

    PubMed

    Gao, Feng; Yang, Feng-Lei; Zhu, Guang-Zhou; Zhao, Yue

    2015-11-18

    The first two families of homodinuclear lanthanide(iii) complexes, formulated as [(LOEt)2Ln2(L1)] and [(LOEt)2Ln2(L2)] (Ln(3+) = Dy(3+), Tb(3+), Ho(3+), Gd(3+), and Y(3+); L1(4-) = 2,2',2'',2'''-[1,2,4,5-benzenetetrayltetrakis(nitrilomethylidyne)]tetrakisphenolate; L2(4-) = 2,2',2'',2'''-[[1,1'-biphenyl]-3,3',4,4'-tetrayltetrakis(nitrilomethylidyne)]tetrakis(4-chlorophenolate); LOEt(-) = (?(5)-cyclopentadienyl)tris(diethylphosphito-p)cobaltate(iii)), were successfully synthesized based on Klui's tripodal building block NaLOEt and two dinucleating Schiff base ligands, and , respectively. Single-crystal X-ray analyses show that these lanthanide complexes have two seven-coordinated metal binding sites, linked to each other with a phenyl or biphenyl bridge. Variable temperature dc magnetic measurements reveal the weakly antiferromagnetic coupling between paramagnetic lanthanide ions, while ac magnetic data exhibit the field-induced relaxation of magnetization for the corresponding Dy2 complexes and . A further magnetic dilution study for suggests that the slow magnetic relaxation originates from the single-ion magnetic behaviour of Dy(3+) ions. PMID:26537229

  2. Exploring DNA binding and nucleolytic activity of few 4-aminoantipyrine based amino acid Schiff base complexes: a comparative approach.

    PubMed

    Raman, N; Sakthivel, A; Pravin, N

    2014-05-01

    A series of novel Co(II), Cu(II), Ni(II) and Zn(II) complexes were synthesized from Schiff base(s), obtained by the condensation of 4-aminoantipyrine with furfural and amino acid (glycine(L1)/alanine(L2)/valine(L3)) and respective metal(II) chloride. Their structural features and other properties were explored from the analytical and spectral methods. The binding behaviors of the complexes to calf thymus DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The intrinsic binding constants for the above synthesized complexes are found to be in the order of 10(2) to 10(5) indicating that most of the synthesized complexes are good intercalators. The binding constant values (Kb) clearly indicate that valine Schiff-base complexes have more intercalating ability than alanine and glycine Schiff-base complexes. The results indicate that the complexes bind to DNA through intercalation and act as efficient cleaving agents. The in vitro antibacterial and antifungal assay indicates that these complexes are good antimicrobial agents against various pathogens. The IC50 values of [Ni(L1)2] and [Zn(L1)2] complexes imply that these complexes have preferable ability to scavenge hydroxyl radical. PMID:24566120

  3. Exploring DNA binding and nucleolytic activity of few 4-aminoantipyrine based amino acid Schiff base complexes: A comparative approach

    NASA Astrophysics Data System (ADS)

    Raman, N.; Sakthivel, A.; Pravin, N.

    A series of novel Co(II), Cu(II), Ni(II) and Zn(II) complexes were synthesized from Schiff base(s), obtained by the condensation of 4-aminoantipyrine with furfural and amino acid (glycine(L1)/alanine(L2)/valine(L3)) and respective metal(II) chloride. Their structural features and other properties were explored from the analytical and spectral methods. The binding behaviors of the complexes to calf thymus DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. The intrinsic binding constants for the above synthesized complexes are found to be in the order of 102 to 105 indicating that most of the synthesized complexes are good intercalators. The binding constant values (Kb) clearly indicate that valine Schiff-base complexes have more intercalating ability than alanine and glycine Schiff-base complexes. The results indicate that the complexes bind to DNA through intercalation and act as efficient cleaving agents. The in vitro antibacterial and antifungal assay indicates that these complexes are good antimicrobial agents against various pathogens. The IC50 values of [Ni(L1)2] and [Zn(L1)2] complexes imply that these complexes have preferable ability to scavenge hydroxyl radical.

  4. The aromatic fluctuation index (FLU): A new aromaticity index based on electron delocalization

    NASA Astrophysics Data System (ADS)

    Matito, Eduard; Duran, Miquel; Sol, Miquel

    2005-01-01

    In this work, the aromatic fluctuation index (FLU) that describes the fluctuation of electronic charge between adjacent atoms in a given ring is introduced as a new aromaticity measure. This new electronic criterion of aromaticity is based on the fact that aromaticity is related to the cyclic delocalized circulation of ? electrons. It is defined not only considering the amount of electron sharing between contiguous atoms, which should be substantial in aromatic molecules, but also taking into account the similarity of electron sharing between adjacent atoms. For a series of rings in 15 planar polycyclic aromatic hydrocarbons, we have found that, in general, FLU is strongly correlated with other widely used indicators of local aromaticity, such as the harmonic-oscillator model of aromaticity, the nucleus independent chemical shift, and the para-delocalization index (PDI). In contrast to PDI, the FLU index can be applied to study the aromaticity of rings with any number of members and it can be used to analyze both the local and global aromatic character of rings and molecules.

  5. Ligational behavior of Schiff bases towards transition metal ion and metalation effect on their antibacterial activity

    NASA Astrophysics Data System (ADS)

    Devi, Jai; Batra, Nisha; Malhotra, Rajesh

    2012-11-01

    New Schiff bases pyrazine-2-carboxylicacid (phenyl-pyridin-2-yl-methylene)-hydrazide (Hpch-bp) HL1 and pyrazine-2-carboxylicacid (pyridin-2-ylmethylene)-hydrazide (Hpch-pc) HL2 derived from condensation of pyrazine carboxylic hydrazide (Hpch) with 2-benzoyl pyridine (bp) or pyridine 2-carbaldehyde (pc) and their transition metal complexes of type ML(1-2)2 have been synthesized, where M = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II). Characterization of ligands and their metal complexes was carried out by elemental analysis, conductimetric studies, magnetic susceptibility, spectroscopic techniques (IR, UV-VIS, NMR, ESR, Mass) and thermogravimetric analysis. The physico-chemical studies revealed octahedral geometry or distorted octahedral geometry around metal ion. These azomethine Schiff base ligands acted as tridentate ? coordinating through carbonyl, azomethine and pyridine nitrogen present in the ligand. The thermodynamic and thermal properties of the complexes have been investigated and it was observed on the basis of these studies that thermal stability of complexes follows the order Mn < Zn < Cu < Co < Ni. The ligands and their complexes were tested for in vitro antibacterial activity at different concentrations against bacteria viz. Gram positive Bacillus subtilis, Micrococcus luteus and Gram negative Pseudomonas aeruginosa, Pseudomonas mendocina. A marked enhancement in biocidal activity of the ligands under similar experimental conditions was observed as a consequence of coordination with metal ions. The trend of growth inhibition in the complexes was found to be in the order: Cu > Mn > Ni > Co > Zn.

  6. Antibacterial and Antifungal Studies on Some Schiff Base Complexes of Zinc(II)

    PubMed Central

    Joseyphus, R. Selwin

    2008-01-01

    Two Schiff base ligands L1 and L2 were obtained by the condensation of glycylglycine respectively with imidazole-2-carboxaldehyde and indole-3-carboxaldehyde and their complexes with Zn(II) were prepared and characterized by microanalytical, conductivity measurement, IR, UV-Vis., XRD and SEM. The molar conductance measurement indicates that the Zn(II) complexes are 1 : 1 electrolytes. The IR data demonstrate the tetradentate binding of L1 and tridentate binding of L2. The XRD data show that Zn(II) complexes with L1 and L2 have the crystallite sizes of 53 and 61 nm respectively. The surface morphology of the complexes was studied using SEM. The in vitro biological screening effects of the investigated compounds were tested against the bacterial species Staphylococcus aureus, Escherichia coli, Klebsiella pneumaniae, Proteus vulgaris and Pseudomonas aeruginosa and fungal species Aspergillus niger, Rhizopus stolonifer, Aspergillus flavus, Rhizoctonia bataicola and Candida albicans by the disc diffusion method. A comparative study of inhibition values of the Schiff base ligands and their complexes indicates that the complexes exhibit higher antimicrobial activity than the free ligands. Zinc ions are proven to be essential for the growth-inhibitor effect. The extent of inhibition appeared to be strongly dependent on the initial cell density and on the growth medium. PMID:23990740

  7. Synthesis and Spectral Characterization of Antifungal Sensitive Schiff Base Transition Metal Complexes

    PubMed Central

    Sakthivel, A.; Rajasekaran, K.

    2007-01-01

    New N2O2 donor type Schiff base has been designed and synthesized by condensing acetoacetanilido-4-aminoantipyrine with 2-aminobenzoic acid in ethanol. Solid metal complexes of the Schiff base with Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) metal ions were synthesized and characterized by elemental analyses, magnetic susceptibility, molar conduction, fast atom bombardment (FAB) mass, IR, UV-Vis, and 1H NMR spectral studies. The data show that the complexes have the composition of ML type. The UV-Vis. and magnetic susceptibility data of the complexes suggest a square-planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The in vitro antifungal activities of the compounds were tested against fungi such as Aspergillus niger, Aspergillus flavus, Rhizopus stolonifer, Candida albicans, Rhizoctonia bataicola and Trichoderma harizanum. All the metal complexes showed stronger antifungal activities than the free ligand. The minimum inhibitory concentrations (MIC) of the metal complexes were found in the range of 10~31 g/ml. PMID:24015086

  8. Gelatin Nanofiber Matrices Derived from Schiff Base Derivative for Tissue Engineering Applications.

    PubMed

    Jaiswal, Devina; James, Roshan; Shelke, Namdev B; Harmon, Matthew D; Brown, Justin L; Hussain, Fazle; Kumbar, Sangamesh G

    2015-11-01

    Electrospinning of water-soluble polymers and retaining their mechanical strength and bioactivity remain challenging. Volatile organic solvent soluble polymers and their derivatives are preferred for fabricating electrospun nanofibers. We report the synthesis and characterization of 2-nitrobenzyl-gelatin (N-Gelatin)--a novel gelatin Schiff base derivative--and the resulting electrospun nanofiber matrices. The 2-nitrobenzyl group is a photoactivatable-caged compound and can be cleaved from the gelatin nanofiber matrices following UV exposure. Such hydrophobic modification allowed the fabrication of gelatin and blend nanofibers with poly(caprolactone) (PCL) having significantly improved tensile properties. Neat gelatin and their PCL blend nanofiber matrices showed a modulus of 9.08 1.5 MPa and 27.61 4.3 MPa, respectively while the modified gelatin and their blends showed 15.63 2.8 MPa and 24.47 8.7 MPa, respectively. The characteristic infrared spectroscopy band for gelatin Schiff base derivative at 1560 cm(-1) disappeared following exposure to UV light indicating the regeneration of free NH2 group and gelatin. These nanofiber matrices supported cell attachment and proliferation with a well spread morphology as evidenced through cell proliferation assay and microscopic techniques. Modified gelatin fiber matrices showed a 73% enhanced cell attachment and proliferation rate compared to pure gelatin. This polymer modification methodology may offer a promising way to fabricate electrospun nanofiber matrices using a variety of proteins and peptides without loss of bioactivity and mechanical strength. PMID:26554164

  9. Schiff-base deprotonation is mandatory for light-dependent rhodopsin phosphorylation.

    PubMed Central

    Seckler, B; Rando, R R

    1989-01-01

    The absorption of light by rhodopsin leads to the formation of an activated intermediate (R*) capable of catalysing the exchange of GTP for GDP in a retinal guanine-nucleotide-binding regulatory protein (transducin). The ability of R* to function as a catalyst is terminated by the rhodopsin kinase. The 10 nonactive-site lysine residues of rhodopsin can be reductively dimethylated to form permethylated rhodopsin (PMRh). This derivative is phosphorylated to the same extent as rhodopsin after photolysis. The monomethylation of the active-site lysine residue of PMRh yields active-site-methylated rhodopsin (AMRh). It had previously been shown, by using AMRh, that the formation of R* and its spectroscopic signature metarhodopsin II requires the photochemically induced deprotonation of the active-site Schiff base [Longstaff, Calhoon & Rando (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 4209-4213]. Here it is demonstrated that active-site Schiff-base deprotonation is also mandatory in the formation of the form of photolyzed rhodopsin that is susceptible to phosphorylation by rhodopsin kinase. In terms of the spectroscopically defined rhodopsin intermediates, this means that only metarhodopsin II and possibly metarhodopsin III are the actual substrates for rhodopsin kinase. PMID:2604728

  10. Ultrafast Excited State Dynamics of the Protonated Schiff Base of All-trans Retinal in Solvents

    PubMed Central

    Zgrabli?, Goran; Votchovsky, Kislon; Kindermann, Maik; Haacke, Stefan; Chergui, Majed

    2005-01-01

    We present a comparative study of the ultrafast photophysics of all-trans retinal in the protonated Schiff base form in solvents with different polarities and viscosities. Steady-state spectra of retinal in the protonated Schiff base form show large absorption-emission Stokes shifts (65008100 cm?1) for both polar and nonpolar solvents. Using a broadband fluorescence up-conversion experiment, the relaxation kinetics of fluorescence is investigated with 120 fs time resolution. The time-zero spectra already exhibit a Stokes-shift of ?6000 cm?1, indicating depopulation of the Franck-Condon region in ?100 fs. We attribute it to relaxation along skeletal stretching. A dramatic spectral narrowing is observed on a 150 fs timescale, which we assign to relaxation from the S2 to the S1 state. Along with the direct excitation of S1, this relaxation populates different quasistationary states in S1, as suggested from the existence of three distinct fluorescence decay times with different decay associated spectra. A 0.50.65 ps decay component is observed, which may reflect the direct repopulation of the ground state, in line with the small isomerization yield in solvents. Two longer decay components are observed and are attributed to torsional motion leading to photo-isomerization. The various decay channels show little or no dependence with respect to the viscosity or dielectric constant of the solvents. This suggests that in the protein, the bond selectivity of isomerization is mainly governed by steric effects. PMID:15792984

  11. Design, spectral characterization and biological studies of transition metal(II) complexes with triazole Schiff bases

    NASA Astrophysics Data System (ADS)

    Hanif, Muhammad; Chohan, Zahid H.

    2013-03-01

    A new series of three biologically active triazole derived Schiff base ligands L1-L3 have been synthesized in equimolar reaction of 3-amino-1H-1,2,4-triazole with pyrrol-2-carboxaldehyde, 4-bromo-thiophene-2-carboxaldehyde, and 5-iodo-2-hydroxy benzaldehyde. The prepared Schiff bases were used for further complex formation reaction with different metal elements like Co(II), Ni(II), Cu(II) and Zn(II) as chlorides by using a molar ratio of ligand:metal as 2:1. The structure and bonding nature of all the compounds were identified by their physical, spectral and analytical data. All the metal(II) complexes possessed an octahedral geometry except the Cu(II) complexes which showed a distorted octahedral geometry. All the synthesized compounds, were studied for their in vitro antibacterial, and antifungal activities, against four Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Bacillus subtilis and Staphylococcus aureus) bacterial strains and against six fungal strains (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata) by using agar-well diffusion method. It has been shown that all the synthesized compounds showed moderate to significant antibacterial activity against one or more bacterial strains. In vitro Brine Shrimp bioassay was also carried out to investigate the cytotoxic properties of these compounds. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination.

  12. Spectrophotometric investigation of interaction between iodine and pentadentate Schiff base ligands.

    PubMed

    Khouba, Z; Benabdallah, T; Maschke, U

    2014-05-01

    The interaction between iodine as an electron acceptor (A), and three pentadentate Schiff bases, 1,3-bis(salicylideneamino)-2-propanol (SB1), 1,3-bis(2-hydroxy-1-naphthylideneamino)-2-propanol (SB2), and 1,3-bis[1-(pyridine-2-yl)methylideneamino]-2-propanol (SB3), as electron donor systems (D), was studied spectrophotometrically in methanol at 28 C. Equilibrium constants K(AD) and molar extinction coefficients ?(AD) of the donor-acceptor complexes (AD) were determined using the modified Benesi-Hildebrand equation in conjunction with the non linear fit analysis. The method shows the formation of 1:1 type complexes as major species in solution. The free energy changes ?G and the energy of the charge transfer band E(CT) were also calculated for all complexes. The iodine complex derived from SB2 seems to be more stable than those derived from SB3 and SB1. On the other hand, the ionization potential I(D) of each Schiff base was estimated from the corresponding complex band energy, using an empirical equation. An inverse relationship between I(D) and K(AD) values was found. Blue and red shift observed for the 445 nm band of iodine were also discussed on the basis of theoretical considerations. PMID:24530710

  13. Spectrophotometric investigation of interaction between iodine and pentadentate Schiff base ligands

    NASA Astrophysics Data System (ADS)

    Khouba, Z.; Benabdallah, T.; Maschke, U.

    The interaction between iodine as an electron acceptor (A), and three pentadentate Schiff bases, 1,3-bis(salicylideneamino)-2-propanol (SB1), 1,3-bis(2-hydroxy-1-naphthylideneamino)-2-propanol (SB2), and 1,3-bis[1-(pyridine-2-yl)methylideneamino]-2-propanol (SB3), as electron donor systems (D), was studied spectrophotometrically in methanol at 28 °C. Equilibrium constants KAD and molar extinction coefficients ɛAD of the donor-acceptor complexes (AD) were determined using the modified Benesi-Hildebrand equation in conjunction with the non linear fit analysis. The method shows the formation of 1:1 type complexes as major species in solution. The free energy changes ΔG° and the energy of the charge transfer band ECT were also calculated for all complexes. The iodine complex derived from SB2 seems to be more stable than those derived from SB3 and SB1. On the other hand, the ionization potential ID of each Schiff base was estimated from the corresponding complex band energy, using an empirical equation. An inverse relationship between ID and KAD values was found. Blue and red shift observed for the 445 nm band of iodine were also discussed on the basis of theoretical considerations.

  14. Synthetic, structural and biological properties of binuclear complexes with some Schiff bases.

    PubMed

    Patil, Raju M

    2007-01-01

    The complexes of Co(II), Ni(II) and Cu(II) with N,N'-bis-[5-X-salicylidene]-4,4'-diaminodibenzyl, abbreviated as H2-XSalPDADB (X = -H, -CH3, -Br) have been synthesized and investigated by elemental analysis, electrical conductance, magnetic, spectral and thermal studies. The molar conductivity data indicate that the complexes are non-electrolytes. Analytical data support 1:1 (M:L) stoichiometry. The reflectance spectra along with the magnetic data suggest pseudo-tetrahedral geometry for the complexes. The Schiff bases function as tetradentate ligands coordinating through ON-NO donor system. Substitution in the phenyl ring of the complexes produces shift in the azomethine v(C=N) stretching vibrational frequency, which is related to the Hammett's substituent perameter (sigma). The 1H-NMR data reveal that all Schiff bases exist in enol-iminic form. Various ESR parameters for copper complexes have been calculated. The compounds have been screened for their biological activities. PMID:18536160

  15. A study of in vitro antibacterial activity of lanthanides complexes with a tetradentate Schiff base ligand

    PubMed Central

    Al Momani, Waleed Mahmoud; Taha, Ziyad Ahmed; Ajlouni, Abdulaziz Mahmoud; Shaqra, Qasem Mohammad Abu; Al Zouby, Muaz

    2013-01-01

    Objective To establish the antibacterial activity of lanthanides complexes with a tetradentate Schiff base ligand L. Methods (N, N?-bis (1-naphthaldimine)-o-phenylenediamine) was prepared from the condensation of 2-hydroxy-1-naphthaldehyde with o-phenylenediamine in a molar ratio of 2:1. The antimicrobial activity of the resultant Ln (III) complexes was investigated using agar well diffusion and micro-broth dilution techniques; the latter was used to establish the minimum inhibitory concentrations for each compound investigated. Results Most of Ln (III) complexes were found to exhibit antibacterial activities against a number of pathogenic bacteria with MICs ranging between 1.95-250.00 g/mL. Staphylococcus aureus was the most susceptible bacterial species to [LaL(NO3)2(H2O)](NO3) complex while Shigella dysenteriae and Escherichia coli required a relatively higher MIC (250 g/mL). The complexes La (III) and Pr (III) were effective inhibitors against Staphylococcus aureus, whereas Sm (III) complex was effective against Serratia marcescens. On the other hand, Gd (III), La (III) and Nd (III) were found to be more potent inhibitors against Pseudomonas aeruginosa than two of commonly used antibiotics. The remaining Ln (III) complexes showed no remarkable activity as compared to the two standard drugs used. Conclusions Tetradentate Schiff base ligand L and its complexes could be a potential antibacterial compounds after further investigation. PMID:23646299

  16. Two different forms of metarhodopsin II: Schiff base deprotonation precedes proton uptake and signaling state.

    PubMed Central

    Arnis, S; Hofmann, K P

    1993-01-01

    Rhodopsin is a retinal protein and a G-protein-coupled receptor; it shares with both of these families the seven helix structure. To generate the G-interacting helix-loop conformation, generally identified with the 380-nm absorbing metarhodopsin II (MII) photoproduct, the retinal Schiff base bond to the apoprotein must be deprotonated. This occurs as a key event also in the related retinal proteins, sensory rhodopsins, and the proton pump bacteriorhodopsin. In MII, proton uptake from the aqueous phase must be involved as well, since its formation increases the pH of the aqueous medium and is accelerated under acidic conditions. In the native membrane, the pH effect matches MII formation kinetically, suggesting that intramolecular and aqueous protonation changes contribute in concert to the protein transformation. We show here, however, that proton uptake, as indicated by bromocresol purple, and Schiff base deprotonation (380-nm absorption change) show different kinetics when the protein is solubilized in suitable detergents. Our data are consistent with a two-step reaction: Images Fig. 6 PMID:8356093

  17. Fast O2 Binding at Dicopper Complexes Containing Schiff-Base Dinucleating Ligands

    PubMed Central

    Company, Anna; Gmez, Laura; Mas-Ballest, Rubn; Korendovych, Ivan V.; Ribas, Xavi; Poater, Albert; Parella, Teodor; Fontrodona, Xavier; Benet-Buchholz, Jordi; Sol, Miquel; Que, Lawrence; Rybak-Akimova, Elena; Costas, Miquel

    2008-01-01

    A new family of dicopper(I) complexes [CuI2RL](X)2, (R = H, 1X, R = tBu, 2X and R = NO2, 3X, X = CF3SO3, ClO4, SbF6 or BArF, BArF = [B{3,5-(CF3)2-C6H3}4]?), where RL is a Schiff-base ligand containing two tridentate binding sites linked by a xylyl spacer have been prepared, characterized, and their reaction with O2 studied. The complexes were designed with the aim of reproducing structural aspects of the active site of type 3 dicopper proteins; they contain two three-coordinate copper sites and a rather flexible podand ligand backbone. The solid state structures of 1ClO4, 2CF3SO3, 2ClO4 and 3BArFCH3CN have been established by single crystal X-ray diffraction analysis. 1ClO4 adopts a polymeric structure in solution while 2CF3SO3, 2ClO4 and 3BArFCH3CN are monomeric. The complexes have been studied in solution by means of 1H and 19F NMR spectroscopy, which put forward the presence of dynamic processes in solution. 1-3BArF and 1-3CF3SO3 in acetone react rapidly with O2 to generate metaestable [CuIII2(?-O)2(RL)]2+ 1-3(O2) and [CuIII2(?-O)2(CF3SO3)(RL)]+ 1-3(O2)(CF3SO3) species, respectively that have been characterized by UV-vis spectroscopy and resonance Raman analysis. Instead, reaction of 1-3BArF with O2 in CH2Cl2 results in intermolecular O2 binding. DFT methods have been used to study the chemical identities and structural parameters of the O2 adducts, and the relative stability of the CuIII2(?-O)2 form with respect to the CuII2(?-?2: ?2-peroxo) isomer. The reaction of 1X, X = CF3SO3 and BArF with O2 in acetone has been studied by stopped-flow exhibiting an unexpected very fast reaction rate (k = 3.82(4) 103 M?1s?1, ?H = 4.9 0.5 kJmol?1, ?S = ?148 5 JK?1mol?1), nearly three orders of magnitude faster than in the parent [CuI2(m-XYLMeAN)]2+. Thermal decomposition of 1-3(O2) does not result in aromatic hydroxylation. The mechanism and kinetics of O2 binding to 1X (X = CF3SO3 and BArF) is discussed and compared with those associated to selected examples of reported models of O2-processing copper proteins. A synergistic role of the copper ions in O2 binding and activation is clearly established from this analysis. PMID:17500512

  18. Syntheses, crystal structures, anticancer activities of three reduce Schiff base ligand based transition metal complexes

    NASA Astrophysics Data System (ADS)

    Chang, Hui-Qin; Jia, Lei; Xu, Jun; Zhu, Tao-Feng; Xu, Zhou-Qing; Chen, Ru-Hua; Ma, Tie-Liang; Wang, Yuan; Wu, Wei-Na

    2016-02-01

    Three nickel(II) complexes, [Ni2(L1)2(tren)2(H2O)](ClO4)3 (1), [NiL2(tren)2](ClO4)·2.5H2O (2), [NiL2(tren)2]I·1.5H2O·CH3OH (3) based on amino acid reduced Schiff ligands are synthesized and characterized by physico-chemical and spectroscopic methods. The results show that in all complexes, the amino acid ligand is deprotonated and acts as an anionic ligand. In the dinuclear complex 1, each Ni(II) atom has a distorted octahedron geometry while with different coordination environment. However, the complexes 2 and 3 are mononuclear, almost with the same coordination environment. Furthermore, in vitro experiments are carried out, including MTT assay, Annexin V/PI flow cytometry and western blotting, to assess whether the complexes have antitumor effect. And the results show that all the three complexes have moderate anticancer activity towards human hepatic cancer (HepG2), human cervical cancer (HeLa) and human prostate (PC3) cell lines, in a concentration dependent way. The complex 1 exhibit higher cytotoxicity than the other two complexes and can induce human hepatic cancer cell (HepG2) to cell apoptosis by activating caspase 3.

  19. Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands

    PubMed Central

    Abou-Hussein, Azza A.; Linert, Wolfgang

    2014-01-01

    Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultravioletvisible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms. PMID:24070648

  20. Synthesis, spectroscopic, coordination and biological activities of some organometallic complexes derived from thio-Schiff base ligands

    NASA Astrophysics Data System (ADS)

    Abou-Hussein, Azza A.; Linert, Wolfgang

    2014-01-01

    Two series of mono- and binuclear complexes cyclic or acyclic thio-ferocine Schiff base ligands, derived from the condensation of 2-aminobenzenthiol (L) with monoacetyl ferrocene in the molar ratio 1:1 or in the molar ratio 1:2 for diacetyl ferocine have been prepared. The condensation reactions yield the corresponding Schiff Base ligands, HLa-Maf and H2Lb-Daf. The chelation of the ligands to metal ions occurs through the sulfur of the thiol group as well as the nitrogen atoms of the azomethine group of the ligands. HLa-Maf acts as monobasic bidentate or dibasic tetradentate, while H2Lb-Daf behaves as twice negatively cargend tetradentate ligand. The structures of these ligands were elucidated by elemental analysis, infrared, ultraviolet-visible spectra, as well as 1H NMR spectra. Reactions of the Schiff bases ligands with ruthenium(III), oxovanadium(IV) and dioxouranium(VI) afforded the corresponding transition metal complexes. The properties of the newly prepared complexes were analyse by elemental analyses, infrared, electronic spectra, 1H NMR as well as the magnetic susceptibility and conductivity measurement. The metal complexes exhibits different geometrical arrangements such as octahedral and square pyramidal coordination. Schiff base ligands and their metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi to study their biological activity. All the complexes exhibit antibacterial and antifungal activities against these organisms.

  1. A new multifunctional Schiff-based chemosensor for mask-free fluorimetric and colorimetric sensing of F(-) and CN(.).

    PubMed

    Wan, Li; Shu, Qinghai; Zhu, Jiaping; Jin, Shaohua; Li, Na; Chen, Xin; Chen, Shusen

    2016-05-15

    A Schiff-based chemosensor DSS was designed for selective and simultaneous detection and/or determination of F(-) and CN(-) by distinguishable changes in both solution color and spectroscopic responses within same sample due to the strong emission enhancement at distinct emission bands without any mask. In addition, the sensing mechanism was evaluated by NMR titration and DFT calculations. PMID:26992493

  2. Metal complexes of ONO donor Schiff base ligand as a new class of bioactive compounds; Synthesis, characterization and biological evolution

    NASA Astrophysics Data System (ADS)

    Kumar Naik, K. H.; Selvaraj, S.; Naik, Nagaraja

    2014-10-01

    Present work reviews that, the synthesis of (E)-N";-((7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide [L] ligand and their metal complexes. The colored complexes were prepared of type [M2+L]X2, where M2+ = Mn, Co, Ni, Cu, Sr and Cd, L = (7-hydroxy-4-methyl-2-oxo-2H-chromen-8-yl)methylene)benzohydrazide, X = Cl-. Ligand derived from the condensation of 8-formyl-7-hydroxy-4-methylcoumarin and benzohydrazide in the molar ratio 1:1 and in the molar ratio 1:2 for metal complexes have been prepared. The chelation of the ligand to metal ions occurs through the both oxygen groups, as well as the nitrogen atoms of the azomethine group of the ligand. Reactions of the Schiff base ligand with Manganese(II), Cobalt(II), Nickel(II), Copper(II), Strontium(II), and Cadmium(II) afforded the corresponding metal complexes. The structures of the obtained ligand and their respective metal complexes were elucidated by infra-red, elemental analysis, Double beam UV-visible spectra, conductometric measurements, magnetic susceptibility measurements and also thermochemical studies. The metal complex exhibits octahedral coordination geometrical arrangement. Schiff base ligand and their metal complexes were tested against antioxidants, antidiabetic and antimicrobial activities have been studied. The Schiff base metal complexes emerges effective ?-glucosidase inhibitory activity than free Schiff base ligand.

  3. Sn(IV) Schiff base complexes: triplet photosensitizers for photoredox reactions.

    PubMed

    Grusenmeyer, Tod A; King, Albert W; Mague, Joel T; Rack, Jeffrey J; Schmehl, Russell H

    2014-12-21

    We present the synthesis and characterization of a series of four fluorescent Sn(iv) Schiff base complexes, which also possess long-lived triplet excited states. The complexes absorb visible light (λmax = 420 to 462 nm) and the optical properties are easily tunable without laborious synthetic elaboration. The triplet excited states are not luminescent, but can be observed and followed using nanosecond transient absorption spectroscopy. The lifetimes of the triplet excited states are on the order of 500 μs-10 ms in PMMA matrices. The triplet state energies were estimated via energy transfer reactions with a series of organic triplet acceptors. In addition, the photoexcited complexes react with electron donors and acceptors in solution. These results demonstrate the potential for the development of photosensitizers based on main group elements with high spin orbit coupling constants. PMID:25043697

  4. Coordination properties of hydralazine Schiff base. Synthesis and equilibrium studies of some metal ion complexes

    NASA Astrophysics Data System (ADS)

    Shoukry, Azza A.; Shoukry, Mohamed M.

    2008-08-01

    In the present study, a new ligand is prepared by condensation of hydralazine (1-Hydralazinophthalazine) with 2-butanon-3-oxime. The acid-base equilibria of the schiff-base and the complex formation equilibria with the metal ions as Cu(II), Ni(II), Co(II), Cd(II), Mn(II) and Zn(II) are investigated potentiometrically. The stability constants of the complexes are determined and the concentration distribution diagrams of the complexes are evaluated. The effect of metal ion properties as atomic number, ionic radius, electronegativity and ionization potential are investigated. The isolated solid complexes are characterized by conventional chemical and physical methods. The potential coordination sites are assigned using the i.r. and 1H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies.

  5. ``Test kit'' for detection of biologically important anions: A salicylidene-hydrazine based Schiff base

    NASA Astrophysics Data System (ADS)

    Dalapati, Sasanka; Alam, Md Akhtarul; Jana, Sankar; Karmakar, Saswati; Guchhait, Nikhil

    2013-02-01

    Test paper coated with Schiff base [(N,N/-bis(5-nitro-salicylidene)hydrazine] receptor 1 (host) can selectively detect fluoride and acetate ions (guest) by developing yellow color which can be detected by naked-eye both in aqueous-acetonitrile solution and in solid supported test kit. UV-vis spectral analysis shows that the absorption peaks at 288 and 345 nm of receptor 1 gradually decrease its initial intensity and new red shifted absorption bands at 397 nm and 455 nm gradually appear upon addition of increasing amount of F- and AcO- ions over several tested anions such as HPO4-, Cl, Br, I, NO3-, NO2-, HSO4-, HSO3-, and ClO4- in aqueous-acetonitrile solvent. The colorimetric test results and UV-vis spectral analysis are in well agreement with 1H NMR titration results in d6-DMSO solvent. The receptor 1 forms 1:2 stable complexes with F- and AcO- ions. However, similar kind of observation obtained from UV-vis titrations in presence of AcOH corresponds to 1:1 complexation ratio indicating the formation of H-bonding interaction between the receptor and anions (F- and AcO- ions). So, the observed 1:2 complexation ratio can only be explained on the basis of deprotonation (˜1 eqv.) and H-bonding (˜1 eqv.) interactions [1]. The ratiometric analysis of host-guest complexes corroborates well with the proposed theoretical model optimization at Density Functional Theory (DFT) level.

  6. Synthesis, Structural, and Biological Studies of Some Schiff Bases and Their Metal Complexes

    PubMed Central

    Mishra, A. P.; Soni, Monika

    2008-01-01

    New bidentate or tridentate Schiff bases and their VO(II) and Co(II) complexes formed by the condensation of methyl isobutyl ketone with nicotinamide (mna)/2-amino-4-chlorophenol (map) and 2-hydroxy acetophenone with nicotinamide (han)/isoniazide (hai). Physicochemical characterization has been carried out to determine the structure of the complexes. The FAB mass and thermal data show degradation pattern of the complexes. XRD analysis reveals that all the studied complexes crystallize as tetragonal crystal system. Some of the complexes have been screened for their antimicrobial activity by the well diffusion technique using DMSO as solvent on different species of pathogenic bacteria/fungi, that is, E. coli, S. aureus, S. fecalis, A. niger, T. polysporum, and their antimicrobial potency have been discussed. It has been found that all the complexes are antimicrobially active and show higher activity than the free ligand. Metal chelation affects significantly the antimicrobial/bioactive behavior of the organic ligands. PMID:18670613

  7. First X-ray structural characterization of isatin Schiff base derivative. NMR and theoretical conformational studies

    NASA Astrophysics Data System (ADS)

    Davidovich, Pavel; Novikova, Daria; Tribulovich, Vyacheslav; Smirnov, Sergey; Gurzhiy, Vlad; Melino, Gerry; Garabadzhiu, Alexander

    2014-10-01

    Isatin (1H-indole-2,3-dione) is an endogenous natural compound under intense development in medicinal chemistry. Here, we characterize isatin Schiff base derivative by X-ray crystallography. We describe a derivative that crystallizes E-isomer form in the triclinic space group P 1bar;a = 5.9580 (4) , b = 8.4184 (7) , c = 14.1801 (14) , ? = 73.962 (8), ? = 83.184 (7), ? = 81.143 (6). NMR data show that E-conformer interconverts to the Z-conformer when dissolved, this equilibrium weakly depends on the solvent type. The Z-isomer geometry and the energetics of ?EE-Z interconversion barriers were determined by quantum chemical calculations. The isomers are further characterized by means of FT-IR and UV-Vis spectroscopy.

  8. Synthesis of triazole Schiff bases: novel inhibitors of nucleotide pyrophosphatase/phosphodiesterase-1.

    PubMed

    Khan, Khalid Mohammed; Siddiqui, Salman; Saleem, Muhammad; Taha, Muhammad; Saad, Syed Muhammad; Perveen, Shahnaz; Choudhary, M Iqbal

    2014-11-15

    A series of Schiff base triazoles 1–25 was synthesized and evaluated for their nucleotide pyrophosphatase/phosphodiesterase-1 inhibitory activities. Among twenty-five compounds, three compounds 10 (IC50 = 132.20 ± 2.89 lM), 13 (IC50 = 152.83 ± 2.39 lM), and 22 (IC50 = 251.0 ± 6.64 lM) were identified as potent inhibitors with superior activities than the standard EDTA (IC50 = 277.69 ± 2.52 lM). The newly identified inhibitors may open a new avenue for the development of treatment of phosphodiesterase-I related disorders. These compounds were also evaluated for carbonic anhydrase, acetylcholinesterase and butyrylcholinesterase inhibitory potential and were found to be inactive. The compounds showed non-toxic effect towards PC3 cell lines. PMID:25440732

  9. Synthesis, characterization and biocidal activities of Schiff base polychelates containing polyurethane links in the main chain

    NASA Astrophysics Data System (ADS)

    Hasnain, Sumaiya; Nishat, Nahid

    The concept of combining metallo-polymers with urethanes offers a versatile approach for the synthesis of new polymeric materials. Polyurethane containing transition metals was synthesized by the reaction of Schiff base metal complex with toluene 2,4 diisocyanate. The proposed structures were confirmed by elemental analysis, 1H NMR, 13C NMR and FT-IR. The geometry is determined by UV-Visible spectra and magnetic moment measurements, which reveals that the Mn(II), Co(II) and Ni(II) complexes have octahedral geometry while square planer geometry is reported for Cu(II) and tetrahedral for Zn(II) complex. The antimicrobial activities are determined using the agar well diffusion method with Staphylococcus aureus, Escherichia coli, Bacillus subtilis (bacteria), Aspergillus niger, Candida albicans and Aspergillus flavus (yeast). All the polymeric metal complexes show comparatively good biocidal activity, which is further enhanced after polymerization.

  10. Phenol-quinone tautomerism in (arylazo)naphthols and the analogous Schiff bases: benchmark calculations.

    PubMed

    Ali, S Tahir; Antonov, Liudmil; Fabian, Walter M F

    2014-01-30

    Tautomerization energies of a series of isomeric [(4-R-phenyl)azo]naphthols and the analogous Schiff bases (R = N(CH3)2, OCH3, H, CN, NO2) are calculated by LPNO-CEPA/1-CBS using the def2-TZVPP and def2-QZVPP basis sets for extrapolation. The performance of various density functionals (B3LYP, M06-2X, PW6B95, B2PLYP, mPW2PLYP, PWPB95) as well as MP2 and SCS-MP2 is evaluated against these results. M06-2X and SCS-MP2 yield results close to the LPNO-CEPA/1-CBS values. Solvent effects (CCl4, CHCl3, CH3CN, and CH3OH) are treated by a variety of bulk solvation models (SM8, IEFPCM, COSMO, PBF, and SMD) as well as explicit solvation (Monte Carlo free energy perturbation using the OPLSAA force field). PMID:24417622

  11. Covalent Grafting of the RGD-Peptide onto Polyetheretherketone Surfaces via Schiff Base Formation

    PubMed Central

    Becker, Marc; Lorenz, Steffen; Strand, Dennis; Vahl, Christian-Friedrich; Gabriel, Matthias

    2013-01-01

    In recent years, the synthetic polymer polyetheretherketone (PEEK) has increasingly been used in a number of orthopedic implementations, due to its excellent mechanical properties, bioinertness, and chemical resistance. For in vivo applications, the surface of PEEK, which does not naturally support cell adhesion, has to be modified to improve tissue integration. In the present work we demonstrate a novel wet-chemical modification of PEEK to modify the surface, enabling the covalent grafting of the cell-adhesive RGD-peptide. Modification of the polymer surface was achieved via Schiff base formation using an aliphatic diamine and subsequent crosslinker-mediated immobilization of the peptide. In cell culture experiments with primary osteoblasts it was shown that the RGD-modified PEEK not only significantly promoted cellular adhesion but also strongly enhanced the proliferation of osteoblasts on the modified polymer surface. PMID:24228010

  12. Crystal structures of transition metal complexes with an asymmetrical tridentate Schiff-base ligand

    NASA Astrophysics Data System (ADS)

    Tang, Bei-bei; Sun, Xiao-ping; Liu, Gui-lei; Li, Hui

    2010-12-01

    The asymmetrical tridentate Schiff base ( H 2L = (E)-N'-(2-hydroxybenzylidene)-4-hydroxybenzohydrazide) has been designed and synthesized. The four transition metal complexes with this ligand [Cu(HL)(NO 3)](H 2O) ( 1), [Zn 2(HL) 2(bipy)(H 2O) 2](NO 3) 2 ( 2), [Cu(HL)(H 2O)] 2(NO 3) 2 ( 3) and [Cu(HL)(Me 2NCO)] 2 ( 4) have been studied. The unsaturated coordination site of metal ion in complexes 1 and 2 is occupied by secondary ligand of nitrate and 4,4'-bipyridine. The crystal structure of complex 1 exhibits supramolecular framework with homochirality. Complexes 3 and 4 are dinuclear complexes bridged by the phenol oxygen atoms and the fifth coordination is occupied by H 2O molecular and DMF anion respectively. Hydrogen bonding and ?-? stacking exist in all four complexes to construct supramolecular architecture.

  13. Structure-directed functional properties of symmetrical and unsymmetrical Br-substituted Schiff-bases

    NASA Astrophysics Data System (ADS)

    Marin, Luminita; Harabagiu, Valeria; van der Lee, Arie; Arvinte, Adina; Barboiu, Mihail

    2013-10-01

    This study deals with the investigation of two low molecular weight Schiff base compounds with bromine end groups, differing only by the presence or absence of one methyl group, with the aim of better understanding the solution and the solid state optical, electrochemical and thermic properties generated by the small structural features. The compounds were structurally characterized by 1H NMR, 13C NMR and FTIR spectroscopies, single-crystal X-ray diffraction and gas chromatography analysis. Their thermal behavior was evidenced by polarized light microscopy and differential scanning calorimetry. The single crystal structure of the compounds reveals the versatility of bromine substituents which can adopt an attractive or repulsive electron effect, driven by the structural environment. A comparison of the structures shows that the introduction of a methyl unit as a bulky group hinders completely the π-π stacking interaction within the structural rows, inducing larger intermolecular distances resulting in quite different functional physical and chemical properties.

  14. Derivatives of phosphate Schiff base transition metal complexes: synthesis, studies and biological activity

    NASA Astrophysics Data System (ADS)

    El-Wahab, Z. H. Abd; El-Sarrag, M. R.

    2004-01-01

    We report the synthesis and structural characterization of series of tetra- and hexacoordinate metal chelate complexes of phosphate Schiff base ligands having the general composition LMX nH 2O and L 2MX n (L=phosphate Schiff base ligand; M=Ag +, Mn 2+, Cu 2+, Zn 2+, Cd 2+, Hg 2+, or Fe 3+ and X=NO 3-, Br - or Cl -). The structure of the prepared compounds was investigated using elemental analysis, IR, 1H and 31P NMR, UV-vis, mass spectra, solid reflectance, magnetic susceptibility and conductance measurements as well as conductometric titration. In all the complexes studied, the ligands act as a chelate ligand with coordination involving the phosphate?O-atom and the azomethine?N-atom. IR, solid reflectance spectra and magnetic moment measurement are used to infer the structure and to illustrate the coordination capacity of ligand. IR spectra show the presence of coordinated nitrate and water molecule, the magnetic moments of all complexes show normal magnetic behavior and the electronic spectra of the metal complexes indicate a tetra- and octahedral structure for Mn 2+, octahedral structure of Fe 3+ and both square-planar and distorted octahedral structure for Cu 2+ complexes. Antimicrobial activity of the ligands and their complexes were tested using the disc diffusion method and the chosen strains include Staphylococcus aureus, Pseudomonas aereuguinosa, Klebsiella penumoniae, Escherichia coli, Microsporum canis, Trichophyton mentagrophyte and Trichophyton rubrum. Some known antibiotics are included for the sake of comparison and the chosen antibiotic are Amikacin, Doxycllin, Augmantin, Sulperazon, Unasyn, Septrin, Cefobid, Ampicillin, Nitrofurantion, Traivid and Erythromycin.

  15. Spectroscopic and density functional theory investigation of novel Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Hassan, Walid M. I.; Zayed, Ehab M.; Elkholy, Asmaa K.; Moustafa, H.; Mohamed, Gehad G.

    2013-02-01

    Novel Schiff base (H2L, 1,2-bis[(2-(2-mercaptophenylimino)methyl)phenoxy] ethane) derived from condensation of bisaldehyde and 2-aminothiophenol was prepared in a molar ratio 1:2. The ligand and its metal complexes are fully characterized with analytical and spectroscopic techniques. The metal complexes with Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Th(IV) have been prepared and characterized by elemental analyses, IR and 1H-NMR spectroscopy, thermal and magnetic measurements. The results suggested that the Schiff base is a bivalent anion with hexadentate OONNSS donors derived from the etheric oxygen (O, O'), azomethine nitrogen (N, N') and thiophenolic sulphur (S, S'). The formulae of the complexes were found to be [ML]xH2O (M = Mn(II) (x = 0), Co(II) (x = 1), Ni(II), (x = 1), Cu(II) (x = 2) and Zn(II) (x = 0)) and [ML]nCl (M = Cr(III) (n = 1), Fe(III) (n = 1) and Th(IV) (n = 2)). The thermogravimetric analysis of the complexes shows metal oxide remaining as the final product at 700-1000 C. Density functional theory at the B3LYP/6-31G* level of theory was used to investigate molecular geometry, Mulliken atomic charges and energetics. The synclinal-conformer was found to be responsible for complex formation. The calculation showed that ligand has weak field. Structural deformation and the dihedral angles rotation during complexation were investigated. The binding energy of each complex was calculated. The calculated results are in good agreement with experimental data.

  16. Ultrafast excited state dynamics of the protonated Schiff base of all-trans retinal in solvents.

    PubMed

    Zgrabli?, Goran; Votchovsky, Kislon; Kindermann, Maik; Haacke, Stefan; Chergui, Majed

    2005-04-01

    We present a comparative study of the ultrafast photophysics of all-trans retinal in the protonated Schiff base form in solvents with different polarities and viscosities. Steady-state spectra of retinal in the protonated Schiff base form show large absorption-emission Stokes shifts (6500-8100 cm(-1)) for both polar and nonpolar solvents. Using a broadband fluorescence up-conversion experiment, the relaxation kinetics of fluorescence is investigated with 120 fs time resolution. The time-zero spectra already exhibit a Stokes-shift of approximately 6000 cm(-1), indicating depopulation of the Franck-Condon region in < or =100 fs. We attribute it to relaxation along skeletal stretching. A dramatic spectral narrowing is observed on a 150 fs timescale, which we assign to relaxation from the S(2) to the S(1) state. Along with the direct excitation of S(1), this relaxation populates different quasistationary states in S(1), as suggested from the existence of three distinct fluorescence decay times with different decay associated spectra. A 0.5-0.65 ps decay component is observed, which may reflect the direct repopulation of the ground state, in line with the small isomerization yield in solvents. Two longer decay components are observed and are attributed to torsional motion leading to photo-isomerization. The various decay channels show little or no dependence with respect to the viscosity or dielectric constant of the solvents. This suggests that in the protein, the bond selectivity of isomerization is mainly governed by steric effects. PMID:15792984

  17. Heterogeneity and relaxation dynamics of the photoexcited retinal Schiff base cation in solution.

    PubMed

    Zgrabli?, Goran; Haacke, Stefan; Chergui, Majed

    2009-04-01

    We present steady-state and broadband femtosecond fluorescence spectra of the protonated Schiff base of retinal in various protic and aprotic solvents, as a function of the excitation wavelength. A detailed spectral decomposition of the time-resolved fluorescence spectra allows us to isolate three spectral components: (i) the vibrationally relaxed S(1) fluorescence, (ii) a vibrationally hot S(1) fluorescence, and (iii) a higher-lying emission that undergoes spectral evolution on a time scale of 300-400 fs, which we assign to S(2) fluorescence. The vibrationally "cold" S(1) fluorescence exhibits three decay components upon 400 nm excitation (except in acetonitrile, which has two), but only two of them upon 570 nm excitation. These components clearly demonstrate the heterogeneity of the S(1) state in the sense that emission stems from several shallow potential surface minima. We discuss a connection between these decay channels and reactive and nonreactive excited-state paths on the basis of their solvent-dependent population and of previous high-performance liquid chromatography studies. There is no clear trend of the fluorescence decay times with solvent properties. Rather, a solvent effect manifests itself in acetonitrile, in that the number of fluorescence decay channels is smaller and that the quenching of the hot fluorescence seems more efficient. This effect has to do with the population pathways leading to the fluorescent states. These observations stress the heterogeneity of excited retinal Schiff base, influencing the decay but also the population channels. They also reinforce the claim that steric effects play an important role in the dynamics of the protein. PMID:19249846

  18. Spectral investigation of the intramolecular charge-transfer in some aminotriazole Schiff bases.

    PubMed

    Issa, Y M; Hassib, H B; Abdelaal, H E; Kenawi, I M

    2011-09-01

    3-Amino-1,2,4-triazole Schiff bases were reported to contain intramolecular charge-transfer. The enhancing and depressing effects were remarkable as the substituent was changed from electron-donating to electron-withdrawing groups. The path of the resonating delocalization was reversed in the case of the p-NO2 group. To validate these results we effectively used Weinhold et al's natural bond orbital analysis to assess the UV and FT-IR spectrophotometric monitoring of the change reflected in this phenomenon when the substituent in the benzene ring is altered. The NBO analysis was simulated by ab inito computations at the HF/6-31G(d) level of theory, in order to properly detect any possible presence of a hydrogen bond association. The changes occurring in electron occupancies of double-centered bonds, antibonding orbitals and in lone-pair orbitals appraised the results, as did the s and p character listings of the two-centered bonds and the simultaneous changes occurring in the geometric parameters of the molecules in question. Contrary to its normal preference, in these molecules the nitrogen used sp2 hybrid orbitals for its interaction, housing its electron lone-pair in the third p hybrid orbital. Furthermore, NBO analysis reflected the presence of a very soft intramolecular hydrogen association (C-H??), labelled by UV and FT-IR assignments, between the benzene and triazole rings in all Schiff bases but p-N(Me)2. The n-?* stabilization energy decreased in the order: p-OH>p-OCH3>p-Cl>p-CH3>H>p-NO2>o-OH. The relation between the band position and Hammett substitution constant is interpreted in relation to the molecular structure. PMID:21640640

  19. Spectroscopic studies on two mono nuclear iron (III) complexes derived from a schiff base and an azodye

    SciTech Connect

    Mini, S. Sadasivan, V.; Meena, S. S. Bhatt, Pramod

    2014-10-15

    Two new mono nuclear Fe(III) complexes of an azodye (ANSN) and a Schiff base (FAHP) are reported. The azodye is prepared by coupling diazotized 1-amino-2-naphthol-4-sulphonicacid with 2-naphthol and the Schiff base is prepared by condensing 2-amino-3-hydroxy pyridine with furfural. The complexes were synthesized by the reaction of FeCl{sub 3}Ðœ‡2H{sub 2}O with respective ligands. They were characterized on the basis of elemental analysis and spectral studies like IR, NMR, Electronic and M.ssbauer. Magnetic susceptibility and Molar conductance of complexes at room temperature were studied. Based on the spectroscopic evidences and other analytical data the complexes are formulated as[Fe(ANSN)Cl(H{sub 2}O){sub 2}] and [Fe(FAHP)Cl{sub 2}(H{sub 2}O){sub 2}].

  20. Synthesis, Spectral, and In Vitro Antibacterial Studies of Organosilicon(IV) Complexes with Schiff Bases Derived from Amino Acids

    PubMed Central

    Singh, Har Lal; Singh, Jangbhadur; Mukherjee, A.

    2013-01-01

    The present work stems from our interest in the synthesis, characterization, and antibacterial evaluation of organosilicon(IV) complexes of a class of amino-acid-based Schiff base which have been prepared by the interaction of ethoxytrimethylsilane with the Schiff bases (N OH) in 1?:?1 molar ratio. These complexes have been characterized by elemental analysis, molar conductance, and spectroscopic studies including electronic IR and NMR (1H, 13C, and 29Si) spectroscopy. The analytical and spectral data suggest trigonal bipyramidal geometry around the silicon atom in the resulting complexes. The ligands and their organosilicon complexes have also been evaluated for in vitro antimicrobial activity against bacteria (Bacillus cereus, Nocardia spp., E. aerogenes, Escherichia coli, Klebsiella spp., and Staphylococcus spp.). The complexes were found to be more potent as compared to the ligands. PMID:23983671

  1. Protein changes associated with reprotonation of the Schiff base in the photocycle of Asp96-->Asn bacteriorhodopsin. The MN intermediate with unprotonated Schiff base but N-like protein structure

    NASA Technical Reports Server (NTRS)

    Sasaki, J.; Shichida, Y.; Lanyi, J. K.; Maeda, A.

    1992-01-01

    The difference Fourier transform infrared spectrum for the N intermediate in the photoreaction of the light-adapted form of bacteriorhodopsin can be recorded at pH 10 at 274 K (Pfefferle, J.-M., Maeda, A., Sasaki, J., and Yoshizawa, T. (1991) Biochemistry 30, 6548-6556). Under these conditions, Asp96-->Asn bacteriorhodopsin gives a photoproduct which shows changes in protein structure similar to those observed in N of wild-type bacteriorhodopsin. However, decreased intensity of the chromophore bands and the single absorbance maximum at about 400 nm indicate that the Schiff base is unprotonated, as in the M intermediate. This photoproduct was named MN. At pH 7, where the supply of proton is not as restricted as at pH 10, Asp96-->Asn bacteriorhodopsin yields N with a protonated Schiff base. The Asn96 residue, which cannot deprotonate as Asp96 in wild-type bacteriorhodopsin, is perturbed upon formation of both MN at pH 10 and N at pH 7. We suggest that the reprotonation of the Schiff base is preceded by a large change in the protein structure including perturbation of the residue at position 96.

  2. Comparative Study of Aluminum Complexes Bearing N,O- and N,S-Schiff Base in Ring-Opening Polymerization of ?-Caprolactone and l-Lactide.

    PubMed

    Chang, Meng-Chih; Lu, Wei-Yi; Chang, Heng-Yi; Lai, Yi-Chun; Chiang, Michael Y; Chen, Hsing-Yin; Chen, Hsuan-Ying

    2015-12-01

    A series of Al complexes bearing Schiff base and thio-Schiff base ligands were synthesized, and their application for the ring-opening polymerization of ?-caprolactone (CL) and l-lactide (LA) was studied. It was found that steric effects of the ligands caused higher polymerization rate and most importantly the Al complexes with N,S-Schiff base showed significantly higher polymerization rate than Al complexes with N,O-Schiff base (5-12-fold for CL polymerization and 2-7-fold for LA polymerization). The reaction mechanism of CL polymerization was investigated by density functional theory (DFT). The calculations predicted a lower activation energy for a process involved with an Al complex bearing an N,S-Schiff base ligand (17.6 kcal/mol) than for that of an Al complex bearing an N,O-Schiff base ligand (19.0 kcal/mol), and this magnitude of activation energy reduction is comparable to the magnitude of rate enhancement observed in the experiment. The reduction of activation energy was attributed to the catalyst-substrate destabilization effect. Using a sulfur-containing ligand to decrease the activation energy in the ring-opening polymerization process may be a new strategy to design a new Al complex with high catalytic activity. PMID:26593231

  3. Reactivity of damaged pyrimidines: formation of a Schiff base intermediate at the glycosidic bond of saturated dihydrouridine.

    PubMed

    Jian, Yajun; Lin, Gengjie; Chomicz, Lidia; Li, Lei

    2015-03-11

    DNA glycosylases catalyze the first step of the base excision repair (BER) pathway. The chemistry used by these enzymes for deglycosylation has been largely considered as the chemistry of the oxocarbenium ion, e.g., direct rupture of the C1'-N1 bond resulting in an oxocarbenium ion intermediate. Here we present mechanistic studies revealing the 2'-deoxyribose isomerization and subsequent deglycosylation processes in two pyrimidine lesions: 5,6-dihydro-2'-deoxyuridine (dHdU) and 5,6-dihydrothymidine (dHT), formed via ionizing radiation damage to 2'-deoxycytidine and thymidine, respectively, under anoxic conditions. Acid or heat treatment of these two lesions leads to the production of two pairs of C1' epimers containing a pyranose and a furanose, respectively, indicating that both lesions favor the rupture of the C1'-O4' bond, resulting in a Schiff base intermediate at the N-glycosidic bond. Such a Schiff base intermediate was trapped and characterized by either Pd-catalyzed hydrogenation or thiol-mediated addition reaction. In contrast, in undamaged 2'-deoxyuridine and thymidine, reactions at elevated temperatures lead to the release of nucleobases most likely via the traditional oxocarbenium ion pathway. DFT calculations further support the experimental findings, suggesting that the oxocarbenium ion intermediate is responsible for the deglycosylation process if the integrity of the pyrimidine ring is maintained, while the Schiff base intermediate is preferred if the C5═C6 bond is saturated. Currently, the oxocarbenium ion pathway is indicated to be solely responsible for the deglycosylation in BER enzymes, however our results suggest an alternative Schiff base mechanism which may be responsible for the repair of saturated pyrimidine damages. PMID:25671389

  4. Synthesis and antimicrobial activities of new higher amino acid Schiff base derivatives of 6-aminopenicillanic acid and 7-aminocephalosporanic acid

    NASA Astrophysics Data System (ADS)

    Özdemir (nee Güngör), Özlem; Gürkan, Perihan; Özçelik, Berrin; Oyardı, Özlem

    2016-02-01

    Novel β-lactam derivatives (1c-3c) (1d-3d) were produced by using 6-aminopenicillanic acid (6-APA), 7-aminocephalosporanic acid (7-ACA) and the higher amino acid Schiff bases. The synthesized compounds were characterized by elemental analysis, IR, 1H/13C NMR and UV-vis spectra. Antibacterial activities of all the higher amino acid Schiff bases (1a-3a) (1b-3b) and β-lactam derivatives were screened against three gram negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Acinetobacter baumannii RSKK 02026), three gram positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 07005, Bacillus subtilis ATCC 6633) and their drug-resistant isolates by using broth microdilution method. Two fungi (Candida albicans and Candida krusei) were used for antifungal activity.

  5. Nitrogen and carbon CPMAS NMR investigations of keto-enol tautomerism in asymmetric o-hydroxy Schiff bases

    NASA Astrophysics Data System (ADS)

    Schilf, Wojciech; Kamie?ski, Bohdan; Uarevi?, Krunoslav

    2013-01-01

    The five Schiff bases obtained by condensation of dehydroacetic acid, p-phenylenediamine and derivatives of salicylaldehyde were investigated by 13C and 15N CPMAS NMR methods to find the structure of intramolecular hydrogen bridges. Additionally the 15N NMR spectra in CDCl3 were done. The results obtained in the solid state and in solution were compared with the X-ray previously published for some of investigated compounds. The relatively small influence of substituent in salicylaldehyde unit on proton position was found as well as only small difference in the hydrogen bridges structure in both phases, solution and solid state, which is in contrast with results acquired for Schiff bases obtained from simple aliphatic amines.

  6. Antioxidant, electrochemical, thermal, antimicrobial and alkane oxidation properties of tridentate Schiff base ligands and their metal complexes.

    PubMed

    Ceyhan, Gkhan; elik, Cumali; Uru?, Serhan; Demirta?, ?brahim; Elmasta?, Mahfuz; Tmer, Mehmet

    2011-10-15

    In this study, two Schiff base ligands (HL(1) and HL(2)) and their Cu(II), Co(II), Ni(II), Pd(II) and Ru(III) metal complexes were synthesized and characterized by the analytical and spectroscopic methods. Alkane oxidation activities of the metal complexes were studied on cyclohexane as substrate. The ligands and their metal complexes were evaluated for their antimicrobial activity against Corynebacterium xerosis, Bacillus brevis, Bacillus megaterium, Bacillus cereus, Mycobacterium smegmatis, Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis (as gram-positive bacteria) and Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Yersinia enterocolitica, Klebsiella fragilis, Saccharomyces cerevisiae, and Candida albicans (as gram-negative bacteria). The antioxidant properties of the Schiff base ligands were evaluated in a series of in vitro tests: 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and reducing power activity of superoxide anion radical generated non-enzymatic systems. Electrochemical and thermal properties of the compounds were investigated. PMID:21752697

  7. Antioxidant, electrochemical, thermal, antimicrobial and alkane oxidation properties of tridentate Schiff base ligands and their metal complexes

    NASA Astrophysics Data System (ADS)

    Ceyhan, Gökhan; Çelik, Cumali; Uruş, Serhan; Demirtaş, İbrahim; Elmastaş, Mahfuz; Tümer, Mehmet

    2011-10-01

    In this study, two Schiff base ligands (HL 1 and HL 2) and their Cu(II), Co(II), Ni(II), Pd(II) and Ru(III) metal complexes were synthesized and characterized by the analytical and spectroscopic methods. Alkane oxidation activities of the metal complexes were studied on cyclohexane as substrate. The ligands and their metal complexes were evaluated for their antimicrobial activity against Corynebacterium xerosis, Bacillus brevis, Bacillus megaterium, Bacillus cereus, Mycobacterium smegmatis, Staphylococcus aureus, Micrococcus luteus and Enterococcus faecalis (as Gram-positive bacteria) and Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, Yersinia enterocolitica, Klebsiella fragilis, Saccharomyces cerevisiae, and Candida albicans (as Gram-negative bacteria). The antioxidant properties of the Schiff base ligands were evaluated in a series of in vitro tests: 1,1-diphenyl-2-picrylhydrazyl (DPPH rad ) free radical scavenging and reducing power activity of superoxide anion radical generated non-enzymatic systems. Electrochemical and thermal properties of the compounds were investigated.

  8. Chemical modification of silica gel with synthesized new Schiff base derivatives and sorption studies of cobalt (II) and nickel (II)

    NASA Astrophysics Data System (ADS)

    Kursunlu, Ahmed Nuri; Guler, Ersin; Dumrul, Hakan; Kocyigit, Ozcan; Gubbuk, Ilkay Hilal

    2009-08-01

    In this study, three Schiff base ligands and their complexes were synthesized and characterized by infrared spectroscopy (IR), thermogravimetric analyses (TGA), nuclear magnetic resonance (NMR), elemental analysis and magnetic susceptibility apparatuses. Silica gel was respectively modified with Schiff base derivatives, (E)-2-[(2-chloroethylimino)methyl]phenol, (E)-4-[(2-chloroethylimino)methyl]phenol and N, N'-[1,4-phenilendi(E)methylidene]bis(2-chloroethanamine), after silanization of silica gel by (3-aminopropyl)trimethoxysilane (APTS) by using a suitable method. Characterization of the surface modification was also performed with IR, TGA and elemental analysis. The immobilized surfaces were used for Co(II) and Ni(II) sorption from aqueous solutions and values of sorption were detected by atomic absorption spectrometer (AAS).

  9. Elucidating the exact role of engineered CRABPII residues for the formation of a retinal protonated Schiff base

    SciTech Connect

    Vasileiou, Chrysoula; Wang, Wenjing; Jia, Xiaofei; Lee, Kin Sing Stephen; Watson, Camille T.; Geiger, James H.; Borhan, Babak

    2010-03-04

    Cellular Retinoic Acid Binding Protein II (CRABPII) has been reengineered to specifically bind and react with all-trans-retinal to form a protonated Schiff base. Each step of this process has been dissected and four residues (Lys132, Tyr134, Arg111, and Glu121) within the CRABPII binding site have been identified as crucial for imine formation and/or protonation. The precise role of each residue has been examined through site directed mutagenesis and crystallographic studies. The crystal structure of the R132K:L121E-CRABPII (PDB-3I17) double mutant suggests a direct interaction between engineered Glu121 and the native Arg111, which is critical for both Schiff base formation and protonation.

  10. Synthesis of Schiff base 24-membered trivalent transition metal derivatives with their anti-inflammation and antimicrobial evaluation

    NASA Astrophysics Data System (ADS)

    Kumar, Gajendra; Devi, Shoma; Kumar, Dharmendra

    2016-03-01

    The paper presents the synthesis of macrocyclic complexes [{M(C52H36N12O4)X}X2] of Cr(III), Mn(III) and Fe(III) with Schiff base ligand (C52H36N12O4) obtained through the condensation of 1,4-dicarbonyl phenyl dihydrazide with 1,2-di(1H-indol-1-yl)ethane-1,2-dione. The newly formed Schiff base and its complexes have been characterized with the help of elemental analysis, condensation measurements, magnetic measurements and their structure configuration have been determined by various spectroscopic (electronic, IR, 1H NMR, 13C NMR, GCMS) techniques. The electronic spectra of the complexes indicate a five coordinate square pyramidal geometry of the center metal ion. These metal complexes and ligand were tested for their anti-inflammation and antimicrobial inhibiting potential and compared with standard drugs Phenyl butazone (anti-inflammation), Imipenem (antibacterial) and Miconazole (antifungal).

  11. Spectroscopic characterization of metal complexes of novel Schiff base. Synthesis, thermal and biological activity studies

    NASA Astrophysics Data System (ADS)

    Omar, M. M.; Mohamed, Gehad G.; Ibrahim, Amr A.

    2009-07-01

    Novel Schiff base (HL) ligand is prepared via condensation of 4-aminoantipyrine and 2-aminobenzoic acid. The ligand is characterized based on elemental analysis, mass, IR and 1H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analyses (TGA, DrTGA and DTA). The molar conductance data reveal that all the metal chelates are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a uninegatively tridentate manner with NNO donor sites of the azomethine N, amino N and deprotonated caroxylic-O. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ΔH*, ΔS* and ΔG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia Coli, Pseudomonas aeruginosa, Staphylococcus Pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Shciff base ligand against one or more bacterial species.

  12. The protonation of a retinyl Schiff base: a study by FTIR spectroscopy at low temperature in solution.

    PubMed

    Badilescu, S; de Alencastro, R B; Le-Thanh, H; Richer, G; Sandorfy, C; Vaudreuil, P P; Vocelle, D

    1989-03-01

    The hydrogen bonding-protonation equilibrium for retinyl Schiff base/propionic acid or 3-chloropropionic acid systems was examined by Fourier transform infrared spectroscopy in non polar solutions at temperatures ranging from 25 degrees C to about -150 degrees C. The spectra give evidence for the gradual increase in the degree of protonation as temperature is lowered. The bearing of this on applying low temperature spectroscopic results to physiological conditions in rhodopsin research is discussed. PMID:2734368

  13. Synthesis and Characterization with Antineoplastic, Biochemical, Cytotoxic, and Antimicrobial Studies of Schiff Base Cu(II) Ion Complexes

    PubMed Central

    Haque, M. M.; Kudrat-E-Zahan, Md.; Banu, Laila Arjuman; Islam, Md. Shariful; Islam, M. S.

    2015-01-01

    Copper(II) complexes containing two Schiff base ligands derived from 2-hydroxybenzaldehyde with 2-aminophenol and 3-aminophenol have been synthesized and characterized by means of analytical, magnetic, and spectroscopic methods. Bacteria, fungus, Entamoeba histolytica, and antineoplastic activities of the synthesized complexes have been determined by monitoring the parameters cell growth inhibition, survival time of tumour mice, time-body relation, causing of intraperitoneal cells and macrophages, alkaline phosphatase activity, hematological effect, and biopsy of tumour. PMID:26294901

  14. A semiempirical study of the optimized ground and excited state potential energy surfaces of retinal and its protonated Schiff base

    NASA Technical Reports Server (NTRS)

    Parusel, A. B.; Pohorille, A.

    2001-01-01

    The electronic ground and first excited states of retinal and its Schiff base are optimized for the first time using the semiempirical AM1 Hamiltonian. The barrier for rotation about the C(11)-C(12) double bond is characterized by variation of both the twist angle delta(C(10)-C(11)-C(12)-C(13)) and the bond length d(C(11)-C(12)). The potential energy surface is obtained by varying these two parameters. The calculated ground state rotational barrier is equal to 15.6 kcal/mol for retinal and 20.5 kcal/mol for its Schiff base. The all-trans conformation is more stable by 3.7 kcal/mol than the 11-cis geometry. For the first excited state, S(1,) the 90 degrees twisted geometry represents a saddle point for retinal with the rotational barrier of 14.6 kcal/mol. In contrast, this conformation is an energy minimum for the Schiff base. It can be easily reached at room temperature from the planar minima since it is separated from them by a barrier of only 0.6 kcal/mol. The 90 degrees minimum conformation is more stable than the all-trans by 8.6 kcal/mol. We are thus able to present a reaction path on the S(1) surface of the retinal Schiff base with an almost barrier-less geometrical relaxation into a twisted minimum geometry, as observed experimentally. The character of the ground and first excited singlet states underscores the need for the inclusion of double excitations in the calculations.

  15. Exploring the distribution of copper-Schiff base complex covalently anchored onto the surface of mesoporous MCM 41 silica

    SciTech Connect

    Singh, Udayshankar G. . E-mail: usingh@engr.ucsb.edu; Williams, Ruth T. . E-mail: r.t.williams@open.ac.uk; Hallam, Keith R. . E-mail: k.r.hallam@bristol.ac.uk; Allen, Geoffrey C. . E-mail: g.c.allen@bristol.ac.uk

    2005-11-15

    A series of copper-Schiff base MCM 41 materials, synthesized by post-synthetic grafting, was studied by X-ray photoelectron spectroscopy (XPS) and nitrogen sorption (77 K) to explore distribution of the copper-Schiff base complex immobilized on the porous Si-MCM 41. Additional information on the physico-chemical properties of the functionalized materials was obtained by powder X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), CHN microanalysis, FTIR spectroscopy, {sup 29}Si and {sup 13}C CP MAS NMR spectroscopy. The effect of copper-Schiff base complex loading and reaction times on the surface properties of Si-MCM 41 (surface area and pore parameters) in addition to its distribution within the Si-MCM 41 was explored by nitrogen sorption and XPS coupled with argon etching. Argon etching of a surface to a depth of 45 A confirmed that the copper-Schiff base complex was distributed both on the external surface (pore end) and within the pores of Si-MCM 41. The amount of complex located in the pores at this depth was about one-third of the amount detected on the external surface of MCM 41. Nitrogen sorption isotherms measured at 77 K confirmed the reduction in total pore volume and surface area was the result of pore narrowing of Si-MCM 41 following grafting of complex in the 8 h samples. A significant decrease in surface area and pore volume for the 20 h sample (longer reaction time), with the highest copper loading (0.65 mmol g{sup -1}), confirmed pore blocking in this material. The uneven distribution of the copper complex between the external and internal surface of Si-MCM 41 was attributed to the bulky nature of the complex, which restricted access to the pores.

  16. Synthesis and spectroscopic characterization of cationic mononuclear oxovanadium(IV) complexes with tetradentate Schiff bases as ligands

    NASA Astrophysics Data System (ADS)

    Gangadharmath, Umesh B.; Revankar, Vidyanand K.; Mahale, Vinayak B.

    2002-10-01

    New tetradentate Schiff-base oxovanadium(IV) complexes [VOL']SO 4 (where L'=tetradentate ligands derived from 2,4-dihydroxy 5-acetyl acetophenone and substituted diamines) were prepared and characterized by physico-chemical techniques. All the complexes are monomeric in nature and a square-pyramidal geometry is proposed. Various ligand-field and molecular-orbital parameters have been calculated.

  17. Detection of glycoproteins in polyacrylamide gels using Pro-Q Emerald 300 dye, a fluorescent periodate Schiff-base stain.

    PubMed

    Mehta-D'souza, Padmaja

    2012-01-01

    Pro-Q Emerald 300 glycoprotein stain generates a bright-green fluorescent signal upon reacting with periodic acid-oxidized carbohydrate groups on proteins. With this dye, it is possible to detect proteins directly in the gel without the need to transfer them to a membrane. This dye is more sensitive than the standard periodic acid Schiff's base which uses acidic fuchsin dye. PMID:22585521

  18. Metal Complexes of Macrocyclic Schiff-Base Ligand: Preparation, Characterisation, and Biological Activity

    PubMed Central

    Ahmed, Riyadh M.; Yousif, Enaam I.; Hasan, Hasan A.; Al-Jeboori, Mohamad J.

    2013-01-01

    A new macrocyclic multidentate Schiff-base ligand Na4L consisting of two submacrocyclic units (10,21-bis-iminomethyl-3,6,14,17-tricyclo[17.3.1.18,12]tetracosa-1(23),2,6,8,10,12(24),13,17,19,21,-decaene-23,24-disodium) and its tetranuclear metal complexes with Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) are reported. Na4L was prepared via a template approach, which is based on the condensation reaction of sodium 2,4,6-triformyl phenolate with ethylenediamine in mole ratios of 2?:?3. The tetranuclear macrocyclic-based complexes were prepared from the reaction of the corresponding metal chloride with the ligand. The mode of bonding and overall geometry of the compounds were determined through physicochemical and spectroscopic methods. These studies revealed tetrahedral geometries about Mn, Co, and Zn atoms. However, square planar geometries have been suggested for NiII and CuII complexes. Biological activity of the ligand and its metal complexes against Gram positive bacterial strain Staphylococcus aureus and Gram negative bacteria Escherichia coli revealed that the metal complexes become more potentially resistive to the microbial activities as compared to the free ligand. However, these metal complexes do not exhibit any effects on the activity of Pseudomonas aeruginosa bacteria. There is therefore no inhibition zone. PMID:23935414

  19. A Quantum Chemical and Statistical Study of Phenolic Schiff Bases with Antioxidant Activity against DPPH Free Radical

    PubMed Central

    Anouar, El Hassane

    2014-01-01

    Phenolic Schiff bases are known as powerful antioxidants. To select the electronic, 2D and 3D descriptors responsible for the free radical scavenging ability of a series of 30 phenolic Schiff bases, a set of molecular descriptors were calculated by using B3P86 (Beckes three parameter hybrid functional with Perdew 86 correlation functional) combined with 6-31 + G(d,p) basis set (i.e., at the B3P86/6-31 + G(d,p) level of theory). The chemometric methods, simple and multiple linear regressions (SLR and MLR), principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to reduce the dimensionality and to investigate the relationship between the calculated descriptors and the antioxidant activity. The results showed that the antioxidant activity mainly depends on the first and second bond dissociation enthalpies of phenolic hydroxyl groups, the dipole moment and the hydrophobicity descriptors. The antioxidant activity is inversely proportional to the main descriptors. The selected descriptors discriminate the Schiff bases into active and inactive antioxidants.

  20. DNA Cleavage, Cytotoxic Activities, and Antimicrobial Studies of Ternary Copper(II) Complexes of Isoxazole Schiff Base and Heterocyclic Compounds

    PubMed Central

    Chityala, Vijay Kumar; Sathish Kumar, K.; Macha, Ramesh; Tigulla, Parthasarathy; Shivaraj

    2014-01-01

    Novel mixed ligand bivalent copper complexes [Cu. L. A. ClO4] and [Cu. L. A] where L is Schiff bases, namely 2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-bromophenol (DMIIMBP)/2-((3,4-dimethylisoxazol-5-ylimino)methyl)-4-chlorophenol (DMIIMCP), and A is heterocyclic compound, such as 1,10-phenanthroline (phen)/2,21-bipyridyl (bipy)/8-hydroxyquinoline (oxine)/5-chloro-8-hydroxyquinoline (5-Cl-oxine), have been synthesized. These complexes have been characterized by IR, UV-Vis, ESR, elemental analysis, magnetic moments, TG, and DTA. On the basis of spectral studies and analytical data, five-coordinated square pyramidal/four-coordinated square planar geometry is assigned to all complexes. The ligands and their ternary complexes with Cu(II) have been screened for antimicrobial activity against bacteria and fungi by paper disc method. The antimicrobial studies of Schiff bases and their metal complexes showed significant activity and further it is observed that the metal complexes showed more activity than corresponding Schiff bases. In vitro antitumor activity of Cu(II) complexes was assayed against human cervical carcinoma (HeLa) cancer cells and it was observed that few complexes exhibit good antitumor activity on HeLa cell lines. The DNA cleavage studies have also been carried out on pBR 322 and it is observed that these Cu(II) complexes are capable of cleaving supercoiled plasmid DNA in the presence of H2O2 and UV light. PMID:24895493

  1. Synthesis, characterization and experimental, theoretical, electrochemical, antioxidant and antibacterial study of a new Schiff base and its complexes.

    PubMed

    Baykara, Haci; Ilhan, Salih; Levent, Abdulkadir; Salih Seyitoglu, M; Özdemir, Sadin; Okumuş, Veysi; Öztomsuk, Abdussamet; Cornejo, Mauricio

    2014-09-15

    A new Schiff base ligand was synthesized by reaction of salicylaldehyde with 1,6-bis(4-chloro-2-aminophenoxy)hexane. Then the Schiff base complexes were synthesized by metal salts and the Schiff base. The metal to ligand ratio of metal complexes was found to be 1:1. The Cu(II) complex is proposed to be square planar and the Co(II), Ni(II), Mn(II) and Zn(II) complexes are proposed to be tetrahedral geometry. The Ti(III) and V(III) complexes are proposed to be a capped octahedron in which a seventh ligand has been added to triangular face. The complexes are non-electrolytes as shown by their molar conductivities (ΛM). The structure of metal complexes is proposed from elemental analysis, FT-IR, UV-vis, magnetic susceptibility measurements, molar conductivity measurements, Mass Spectra and thermal gravimetric analysis. In addition antimicrobial and antioxidant studies, cyclic voltammetry of the complexes, theoretical 1H NMR and HOMO-LUMO energy calculations of the new di-functional ligand were done. PMID:24792202

  2. A one-dimensional azido-bridged manganese(III) complex with bidentate Schiff base: Crystal structure and magnetic properties

    SciTech Connect

    Li Wei; Li Zongwei; Li Licun Liao Daizheng; Jiang Zonghui

    2007-10-15

    The synthesis, structural characterization, and magnetic behavior of a novel one-dimensional azido-bridged manganese(III) complex of formula [Mn(L){sub 2}N{sub 3}] (1) is reported, where HL is the bidentate Schiff base obtained from the condensation of salicylaldehyde with 4-methoxy aniline. Complex 1 crystallizes in the monoclinic system, space group P2{sub 1}/n, with a=11.743(4) A, b=24.986(9) A, c=13.081(5) A, {beta}=95.387(7){sup o} and Z=2. The complex is of one-dimensional chain structure with single end-to-end azido bridges and the manganese(III) ion has an elongated octahedral geometry. Magnetic studies show that the weak antiferromagnetic interaction is mediated by the single end-to-end azido bridge with the exchange parameter J=-5.84 cm{sup -1}. - Graphical abstract: A novel azido-bridged manganese(III) complex with bidentate Schiff base ligands has been prepared and characterized structurally and magnetically. The complex is of one-dimensional chain structure with single end-to-end azido bridges in axial positions. Two bidentate Schiff base ligands coordinate in the equatorial mode. The magnetic measurements show that the complex exhibits weak antiferromagnetic interaction.

  3. Synthesis, Spectroscopic, Molecular Structure, and Antibacterial Studies of Dibutyltin(IV) Schiff Base Complexes Derived from Phenylalanine, Isoleucine, and Glycine.

    PubMed

    Singh, Har Lal; Singh, Jangbhadur

    2014-01-01

    New series of organotin(IV) complexes and Schiff bases derived from amino acids have been designed and synthesized from condensation of 1H-indole-2,3-dione, 5-chloro-1H-indole-2,3-dione, and ?-amino acids (phenylalanine, isoleucine, and glycine). All compounds are characterized by elemental analyses, molar conductance measurements, and molecular weight determinations. Bonding of these complexes is discussed in terms of their UV-visible, infrared, and nuclear magnetic resonance ((1)H, (13)C, and (119)Sn NMR) spectral studies. The results suggest that Schiff bases behave as monobasic bidentate ligands and coordinate with dibutyltin(IV) in octahedral geometry according to the general formula [Bu2Sn(L)2]. Elemental analyses and NMR spectral data of the ligands with their dibutyltin(IV) complexes agree with their proposed distorted octahedral structures. Few representative compounds are tested for their in vitro antibacterial activity against Gram-positive (B. cereus, Staphylococcus spp.) and Gram-negative (E. coli, Klebsiella spp.) bacteria. The results show that the dibutyltin complexes are more reactive with respect to their corresponding Schiff base ligands. PMID:25525422

  4. Synthesis, characterization and experimental, theoretical, electrochemical, antioxidant and antibacterial study of a new Schiff base and its complexes

    NASA Astrophysics Data System (ADS)

    Baykara, Haci; Ilhan, Salih; Levent, Abdulkadir; Salih Seyitoglu, M.; zdemir, Sadin; Okumu?, Veysi; ztomsuk, Abdussamet; Cornejo, Mauricio

    2014-09-01

    A new Schiff base ligand was synthesized by reaction of salicylaldehyde with 1,6-bis(4-chloro-2-aminophenoxy)hexane. Then the Schiff base complexes were synthesized by metal salts and the Schiff base. The metal to ligand ratio of metal complexes was found to be 1:1. The Cu(II) complex is proposed to be square planar and the Co(II), Ni(II), Mn(II) and Zn(II) complexes are proposed to be tetrahedral geometry. The Ti(III) and V(III) complexes are proposed to be a capped octahedron in which a seventh ligand has been added to triangular face. The complexes are non-electrolytes as shown by their molar conductivities (?M). The structure of metal complexes is proposed from elemental analysis, FT-IR, UV-vis, magnetic susceptibility measurements, molar conductivity measurements, Mass Spectra and thermal gravimetric analysis. In addition antimicrobial and antioxidant studies, cyclic voltammetry of the complexes, theoretical 1H NMR and HOMO-LUMO energy calculations of the new di-functional ligand were done.

  5. Metal (II) Complexes Derived from Naphthofuran-2-carbohydrazide and Diacetylmonoxime Schiff Base: Synthesis, Spectroscopic, Electrochemical, and Biological Investigation

    PubMed Central

    Sumathi, R. B.; Halli, M. B.

    2014-01-01

    A new Schiff base and a new series of Co(II), Ni(II), Cu(II), Cd(II), and Hg(II) complexes were synthesized by the condensation of naphthofuran-2-carbohydrazide and diacetylmonoxime. Metal complexes of the Schiff base were prepared from their chloride salts of Co(II), Ni(II), Cu(II), Cd(II), and Hg(II) in ethanol. The ligand along with its metal complexes have been characterized on the basis of analytical data, IR, electronic, mass, 1HNMR, ESR spectral data, thermal studies, magnetic susceptibility, and molar conductance measurements. The nonelectrolytic behaviour of the complexes was assessed from the measured low conductance data. The elemental analysis of the complexes confirm the stoichiometry of the type CuL2Cl2 and MLCl2 where M = Ni(II), Co(II), Cd(II), and Hg(II) and L = Schiff base. The redox property of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. In the light of these results, Co(II), Ni(II), and Cu(II) complexes are assigned octahedral geometry, Cd(II), and Hg(II) complexes tetrahedral geometry. In order to evaluate the effect of metal ions upon chelation, both the ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleaving capacity of all the complexes was analysed by agarose gel electrophoresis method. PMID:24592203

  6. Induction of tumor cell apoptosis by taurine Schiff base copper complex is associated the with inhibition of proteasomal activity

    PubMed Central

    ZHANG, XIA; BI, CAIFENG; FAN, YUHUA; CUI, QIUZHI; CHEN, DI; XIAO, YAN; DOU, Q. PING

    2013-01-01

    Schiff bases have been intensively investigated due to their antibacterial and antitumor properties. Copper is a cofactor essential for the tumor angiogenesis processes, whereas other transition metals are not. Consistently, high serum or tissue levels of copper were found in many types of human cancer including breast, prostate, colon, lung, and brain, supporting the idea that copper could be used as a novel selective target for cancer therapies. In the current study we hypothesize that a synthetic taurine Schiff base copper complex (Compound 1) could suppress tumor cell growth via the direct inhibition of proteasome activity. Compound 1 potently inhibits the activity of purified 20S and 26S proteasome in human breast cancer MDA-MB-231 and leukemia Jurkat T cells. Inhibition of tumor cellular proteasomal activity by Compound 1 results in the accumulation of ubiquitinated protein and the proteasome target proteins p27 and Bax, followed by the induction of apoptosis. Our results strongly suggest that taurine Schiff base copper complexes, as potent proteasome inhibitors, have great potential to be developed into novel anticancer drugs. PMID:18949390

  7. Synthesis, Spectroscopic, Molecular Structure, and Antibacterial Studies of Dibutyltin(IV) Schiff Base Complexes Derived from Phenylalanine, Isoleucine, and Glycine

    PubMed Central

    Singh, Har Lal; Singh, Jangbhadur

    2014-01-01

    New series of organotin(IV) complexes and Schiff bases derived from amino acids have been designed and synthesized from condensation of 1H-indole-2,3-dione, 5-chloro-1H-indole-2,3-dione, and α-amino acids (phenylalanine, isoleucine, and glycine). All compounds are characterized by elemental analyses, molar conductance measurements, and molecular weight determinations. Bonding of these complexes is discussed in terms of their UV-visible, infrared, and nuclear magnetic resonance (1H, 13C, and 119Sn NMR) spectral studies. The results suggest that Schiff bases behave as monobasic bidentate ligands and coordinate with dibutyltin(IV) in octahedral geometry according to the general formula [Bu2Sn(L)2]. Elemental analyses and NMR spectral data of the ligands with their dibutyltin(IV) complexes agree with their proposed distorted octahedral structures. Few representative compounds are tested for their in vitro antibacterial activity against Gram-positive (B. cereus, Staphylococcus spp.) and Gram-negative (E. coli, Klebsiella spp.) bacteria. The results show that the dibutyltin complexes are more reactive with respect to their corresponding Schiff base ligands. PMID:25525422

  8. Synthesis, characterization and metal ion-sensing properties of two Schiff base derivatives

    NASA Astrophysics Data System (ADS)

    Xu, Huihua; Tao, Xian; Li, Yueqin; Shen, Yingzhong; Wei, Yanhong

    2012-06-01

    Two new Schiff base derivatives {2,2'-diphenyl-N,N'-bis(2-pyridylmethylene)biphenyl-4,4'-diamine} (1) and {2,2'-diphenyl-N,N'-bis(salicylidene)biphenyl-4,4'-diamine} (2) were synthesized and characterized by means of elemental analysis, 1H NMR, FT-IR, and standard spectroscopy techniques. The molecular structure of 2 has been determined by X-ray single crystal analysis. The analyses of fluorescence properties of the compounds revealed that 1 and 2 are both poorly fluorescent and display sensitive fluorescence responses to a panel of 24 monovalent, divalent, and trivalent metal ions in CH3CN-DMSO (9:1, v/v). Results with imine 1 showed that Fe3+, Cu2+, Zn2+, Cd2+, Mn2+, Zr4+, Hg2+, Cr2+, Pb2+, Sn2+, Bi2+, Al3+, Ce3+, La3+, Sm3+, Gd3+, Nd3+, Eu3+ and Dy3+ yields red shifts in emission and increases in intensity. And the greatest spectral changes for imine 2 include enhancements in emission intensity coupled with red shifts (Zr4+, Sn2+, Al3+ and Zn2+) and strong quenching (Fe3+). The fluorescence enhancement mechanism of 1 and 2 for metal ions is based on: (i) Cdbnd N isomerization; (ii) chelation-enhanced fluorescence (CHEF) effect; and (iii) excited-state intra/intermolecular proton transfer (ESPT).

  9. Synthesis, characterization, biological and catalytic applications of transition metal complexes derived from Schiff base.

    PubMed

    Bushra Begum, A; Rekha, N D; Vasantha Kumar, B C; Lakshmi Ranganatha, V; Khanum, Shaukath Ara

    2014-08-01

    A novel series of Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) complexes have been synthesized from the Schiff base. Structural features were determined by analytical and spectral techniques like IR, (1)H NMR, UV-vis, elemental analysis, molar electric conductibility, magnetic susceptibility and thermal studies. The complexes are found to be soluble in dimethylformamide and dimethylsulfoxide. Molar conductance values in dimethylformamide indicate the non-electrolytic nature of the complexes. Binding of synthesized complexes with calf thymus DNA (CT DNA) was studied. There is significant binding of DNA in lanes 2, 3, and 5. Lanes 4 and 6 are showing more florescence when compared to the control indicating that these molecules are strongly bound to the DNA by inserting themselves between the two stacked base pairs and exhibiting their original property of fluorescence. Angiogenesis study has revealed that the compounds B-2, B-4 and B-5 have potent antitumor efficacy and activation of antiangiogenesis could be one of the possible underlying mechanisms of tumor inhibition. PMID:24915881

  10. Structural, spectroscopic and DFT study of 4-methoxybenzohydrazide Schiff bases. A new series of polyfunctional ligands

    NASA Astrophysics Data System (ADS)

    Ferraresi-Curotto, Vernica; Echeverra, Gustavo A.; Piro, Oscar E.; Pis-Diez, Reinaldo; Gonzlez-Bar, Ana C.

    2015-02-01

    Five Schiff bases obtained from condensation of 4-methoxybenzohydrazide with related aldehydes, namely o-vanillin, vanillin, 5-bromovanillin, 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde were prepared. A detailed structural and spectroscopic study is reported. The crystal structures of four members of the family were determined and compared with one another. The hydrazones obtained from 5-chlorosalicylaldehyde and 5-bromosalicylaldehyde resulted to be isomorphic to each other. The solid-state structures are stabilized by intra-molecular Osbnd H⋯N interactions in salicylaldehyde derivatives between the Osbnd H moiety from the aldehyde and the hydrazone nitrogen atom. All crystals are further stabilized by inter-molecular H-bonds mediated by the crystallization water molecule. A comparative analysis between experimental and theoretical results is presented. The conformational space was searched and geometries were optimized both in gas phase and including solvent effects. The structure is predicted for the compound for which the crystal structure was not determined. Infrared and electronic spectra were measured and assigned with the help of data obtained from computational methods based on the Density Functional Theory.

  11. Theoretical studies of organotin(IV) complexes derived from ONO-donor type schiff base ligands.

    PubMed

    ?irikci, Gkhan; Anc?n, Nilgn Atanal; zta?, Selma Gl

    2015-09-01

    In this work a molecular modeling study was carried out based on a series of organotin(IV) derivatives which were complexed with ONO-Donor type Schiff base ligands to build up a statistical data pool for researchers. For this purpose, various properties of the selected complexes such as energies, band gaps, chemical reactivity descriptors, polarizabilities, geometric parameters, (1)H-NMR, (13)C-NMR chemical shifting values were obtained through density functional theory using B3LYP, CAM-B3LYP, TPSSTPSS, TPSSh, HCTH, wB97XD, and MN12SX functionals. Empirical dispersion corrections were incorporated for some functionals and solvent effects were also taken into account through applying polarizable continuum model (PCM). (1)H-NMR, (13)C-NMR chemical shifts were calculated via linear regression analysis using either gauge invariant atomic orbital (GIAO) or continuous set of gauge transformations (CSGT) methods. While structural properties were being explored, quantitative effects of utilized functionals and empirical dispersion corrections over calculated properties were shown in detail. PMID:26245450

  12. Chemopreventive Evaluation of a Schiff Base Derived Copper (II) Complex against Azoxymethane-Induced Colorectal Cancer in Rats

    PubMed Central

    Hajrezaie, Maryam; Hassandarvish, Pouya; Moghadamtousi, Soheil Zorofchian; Gwaram, Nura Suleiman; Golbabapour, Shahram; NajiHussien, Abdrabuh; Almagrami, Amel Abdullah; Zahedifard, Maryam; Rouhollahi, Elham; Karimian, Hamed; Fani, Somaye; Kamalidehghan, Behnam; Majid, Nazia Abdul; Ali, Hapipah Mohd; Abdulla, Mahmood Ameen

    2014-01-01

    Background Based on the potential of Schiff base compounds to act as sources for the development of cancer chemotherapeutic agents, this in vivo study was performed to investigate the inhibitory properties of the synthetic Schiff base compound Cu(BrHAP)2 on colonic aberrant crypt foci (ACF). Methodology This study involved five groups of male rats. The negative control group was injected with normal saline once a week for 2 weeks and fed 10% Tween 20 for 10 weeks, the cancer control group was subcutaneously injected with 15 mg/kg azoxymethane once per week for two consecutive weeks, the positive control group was injected with 15 mg/kg azoxymethane once per week for two consecutive weeks and 35 mg/kg 5-fluorouracil (injected intra-peritoneally) for 4 weeks, and the experimental groups were first injected with 15 mg/kg azoxymethane once per week for two consecutive weeks and then fed 2.5 or 5 mg/kg of the Schiff base compound once a day for 10 weeks. Application of the Schiff base compound suppressed total colonic ACF formation by up to 72% to 74% (P<0.05) when compared with the cancer control group. Analysis of colorectal specimens revealed that treatments with the Schiff base compound decreased the mean crypt scores in azoxymethane-treated rats. Significant elevations of superoxide dismutase, glutathione peroxidase and catalase activities and a reduction in the level of malondialdehyde were also observed. Histologically, all treatment groups exhibited significant decreases in dysplasia compared to the cancer control group (P<0.05). Immunohistochemical staining demonstrated down-regulation of the PCNA protein. Comparative western blot analysis revealed that COX-2 and Bcl2 were up-regulated and Bax was down-regulated compared with the AOM control group. Conclusion The current study demonstrated that the Cu(BrHAP)2 compound has promising chemoprotective activities that are evidenced by significant decreases in the numbers of ACFs in azoxymethane-induced colon cancer. PMID:24618844

  13. Photoisomerization action spectrum of retinal protonated Schiff base in the gas phase

    SciTech Connect

    Coughlan, N. J. A.; Catani, K. J.; Adamson, B. D.; Wille, U.; Bieske, E. J.

    2014-04-28

    The photophysical behaviour of the isolated retinal protonated n-butylamine Schiff base (RPSB) is investigated in the gas phase using a combination of ion mobility spectrometry and laser spectroscopy. The RPSB cations are introduced by electrospray ionisation into an ion mobility mass spectrometer where they are exposed to tunable laser radiation in the region of the S{sub 1} ← S{sub 0} transition (420–680 nm range). Four peaks are observed in the arrival time distribution of the RPSB ions. On the basis of predicted collision cross sections with nitrogen gas, the dominant peak is assigned to the all-trans isomer, whereas the subsidiary peaks are assigned to various single, double and triple cis geometric isomers. RPSB ions that absorb laser radiation undergo photoisomerization, leading to a detectable change in their drift speed. By monitoring the photoisomer signal as a function of laser wavelength an action spectrum, extending from 480 to 660 nm with a clear peak at 615 ± 5 nm, is obtained. The photoisomerization action spectrum is related to the absorption spectrum of isolated retinal RPSB molecules and should help benchmark future electronic structure calculations.

  14. Synthesis, Characterization, Fluorescence, Photocatalytic and Antibacterial Activity of CdS Nanoparticles Using Schiff Base.

    PubMed

    Ayodhya, Dasari; Venkatesham, M; Kumari, A Santoshi; Reddy, G Bhagavanth; Ramakrishna, D; Veerabhadram, G

    2015-09-01

    Cadmium sulfide nanoparticles (CdS NPs) were successfully prepared using sonochemical method by employing Schiff-base, (2-[(4-methoxy-phenylimino)-methyl]-4-nitro phenol) as a complexing agent. Here, SB is used as a ligand to control the morphology of NPs. XRD patterns and TEM images show that the synthesized CdS NPs have cubic structures with a diameter of about 2-10 nm. The formation of CdS NPs and their optical, structure, thermal and morphologies were studied by means of UV-vis DRS, fluorescence, FTIR, zeta potential, XRD, SEM and TEM. The interactions between CdS NPs and SB were investigated in an aqueous solution using fluorescence spectroscopy. The fluorescence quenching studies suggest that SB quenches the fluorescence of CdS NPs effectively. The degradation kinetics of methyl red (MR) by the photocatalyst was followed by Langmuir-Hinshelwood model. The results revealed that photocatalytic degradation of MR by SB capped CdS NPs could be considered as a practical and reliable technique for the removal of environmental pollutants. The antibacterial activity of samples was evaluated against E. coli, S. aureus and P. aeruginosa and the results were compared. SB and SB capped CdS NPs could be a potential antibacterial compounds after further investigation. PMID:26275559

  15. Syntheses, characterization, biological activities and photophysical properties of lanthanides complexes with a tetradentate Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Taha, Ziyad A.; Ajlouni, Abdulaziz M.; Al Momani, Waleed; Al-Ghzawi, Abeer A.

    2011-10-01

    A tetradentate Schiff base ligand L (N,N'-bis(1-naphthaldimine)-o-phenylenediamine) was prepared from the condensation of 2-hydroxy-1-naphthaldehyde with o-phenylenediamine in a molar ratio of 2:1. New eight lanthanide metal complexes [Ln L(NO 3) 2(H 2O) x](NO 3) {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, x = 0 for Nd, Sm, 1 for La, Gd, Pr, Nd, Dy, and 2 for Tb} were prepared. The characterization and nature of bonding of these complexes were elucidated by elemental analysis, spectral analysis ( 1H NMR, FT-IR, UV-vis), molar conductivity measurements, luminescence spectra and thermogravimetric studies. Analytical and spectral data revealed that the ligand L coordinates to the central Ln(III) ions by its two imine nitrogen atoms and two phenolic oxygen atoms with 1:1 stoichiometry. Under the excitation with 329 nm at room temperature, Tb and Dy complexes exhibited characteristic luminescence of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of Ln(III) complexes found to exhibit antibacterial activities against a number of pathogenic bacteria. We found that the antioxident activity of Ln(III) complexes on DPPH rad is concentration dependent and higher than that of the free ligand L.

  16. Selective Anion Binding by a Cofacial Binuclear Zinc Complex of a Schiff-Base Pyrrole Macrocycle

    PubMed Central

    Devoille, Aline M. J.; Richardson, Patricia; Bill, Nathan; Sessler, Jonathan L.; Love, Jason B.

    2011-01-01

    The synthesis of the new cofacial binuclear zinc complex [Zn2(L)] of a Schiff-base pyrrole macrocycle is reported. It was discovered that the binuclear microenvironment between the two metals of [Zn2(L)] is suited for the encapsulation of anions, leading to the formation of [K(THF)6][Zn2(?-Cl)(L)].2THF and [Bun4N][Zn2(?-OH)(L)] which were characterized by X-ray crystallography. Unusually obtuse Zn-X-Zn angles (X=Cl: 150.54(9) and OH: 157.4(3)) illustrate the weak character of these interactions and the importance of the cleft pre-organization to stabilize the host. In the absence of added anion, aggregation of [Zn2(L)] was inferred and investigated by successive dilutions and by the addition of coordinating solvents to [Zn2(L)] solutions using NMR spectroscopy as well as isothermal microcalorimetry (ITC). On anion addition, evidence for de-aggregation of [Zn2(L)], combined with the formation of the 1:1 host-guest complex, was observed by NMR spectroscopy and ITC titrations. Furthermore, [Zn2(L)] binds to Cl? selectively in THF as deduced from the ITC analyses, while other halides induce only de-aggregation. These conclusions were reinforced by DFT calculations, which indicated that the binding energies of OH? and Cl? were significantly greater than for the other halides. PMID:21391550

  17. Synthesis, molecular structure, and properties of a neutral Schiff base phenolic complex of magnesium

    SciTech Connect

    Polyakov, V.R.; Sharma, V.; Crankshaw, C.L.; Piwnica-Worms, D.

    1998-09-07

    Multidrug resistance (MDR) in cancer mediated by the MDR1 P-glycoprotein (Pgp), a 140--180 kDa plasma membrane protein, renders chemotherapeutic treatment ineffective by pumping a variety of natural product cytotoxic agents and xenobiotic compounds out of cancer cells. Pgp has been a major target for synthesis and development of both therapeutic antagonists that block its transport function and diagnostic radiopharmaceuticals that are transported by the protein for use in functional imaging of Pgp transport activity in tumors in vivo. Most, but not all, compounds that interact with Pgp are hydrophobic and cationic at physiological pH. To further understand the Pgp targeting properties, the authors sought to directly evaluate the effect of charge of the complex on Pgp interactions. This could be done by comparing the cytotoxicity profile of a neutral complex to that of an identical, but positively charged, complex in both drug-sensitive and multidrug-resistant cancer cells. Thus, a neutral analogue of the Ga(III) and Fe(III) complexes was desired. Herein the authors describe the synthesis and structure of a novel neutral Schiff base Mg complex and evaluate its cytotoxic potency in human drug-sensitive KB-3-1 and multi-drug-resistant KB-8-5 tumor cells.

  18. Redox, thermodynamic and spectroscopic of some transition metal complexes containing heterocyclic Schiff base ligands

    NASA Astrophysics Data System (ADS)

    Abu-Hussen, Azza A. A.; Linert, Wolfgang

    2009-09-01

    Complexes of two series of Schiff base ligands, H 2L a and H 2L b derived from the reaction of 2,6-diacetyl pyridine with semicarbazide, H 2L a and thiosemicarbazide, H 2L b, with the metal ions, Co(II), Ni(II), Cu(II), VO(IV) and UO 2(VI) have been prepared. The ligands are characterized by elemental analysis, IR, UV-vis and 1H NMR. The structures of the complexes are investigated with the IR, UV-vis, X-band ESR spectra, 1H NMR and thermal gravimetric analysis as well as conductivity and magnetic moment measurements. The IR-spectra reveal the presence of variable modes of chelation for the investigated ligands. A variety of binuclear or mononuclear complexes were obtained with the two ligands in tri-, tetra or pentadentate forms. The bonding sites are the pyridine nitrogen, two azomethine nitrogen atoms and ketonic oxygen in case of H 2L a or sulphur atoms in case of H 2L b. The Coats-Redfern equation has been used to calculate the kinetic and thermodynamic parameters for the different thermal decomposition steps of some complexes. Cyclic voltammograms of Co(II) and Ni(II) show quasi-reversible peaks. The redox properties and the nature of the electro-active species of the complexes have been characterized.

  19. Synthesis of a novel fluorescent Schiff base as a possible Cu(II) ion selective sensor.

    PubMed

    Yildirim, Mehmet; Kaya, Ismet

    2010-05-01

    In this study a new fluorescent Schiff base; 1,1'-(4,4'-oxybis(4,1-phenylene)bis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)dinaphthalen-2-ol (2-HNA) was synthesized and characterized by FT-IR, UV-vis, and (1)H and (13)C-NMR techniques. Photoluminescent properties of 2-HNA were investigated in different solvents including methanol, THF, DMF, DMSO, acetone, acetonitrile, and dichloromethane. 2-HNA was found to have higher emission intensity and Stoke's shift value (lambda(ST)) in methanol solution. Relative emission intensity changes (I(0)-I/I(0)) of 2-HNA in methanol/water mixtures depending on different Cu(+2) ion concentrations were determined and a linearized plot was obtained. Possible interference of some other transition metal ions was also determined. Sensitivity limit of the new sensor was found to be higher than 5 x 10(-7) mol/L. 2-HNA has quite high selectivity against Cu(+2) ion and, thus, can be used as a new fluorescence Cu(+2) ion sensor in practice. PMID:20213242

  20. Corrosion inhibition of mild steel by some schiff base compounds in hydrochloric acid

    NASA Astrophysics Data System (ADS)

    Ashassi-Sorkhabi, H.; Shaabani, B.; Seifzadeh, D.

    2005-01-01

    The corrosion inhibition of mild steel in 1 M HCl by benzylidene-pyridine-2-yl-amine (A), (4-benzylidene)-pyridine-2-yl-amine (B) and (4-chloro-benzylidene)-pyridine-2-yl-amine (C) has been studied at 25 C using electrochemical and weight loss measurements. Polarization curves reveal that the used compounds are mixed type inhibitors. Results show that inhibition efficiency increases when the inhibitor concentration increases. The inhibition efficiency changes with the type of functional groups substituted on benzene ring. The experimentally obtained adsorption isotherms follow the Langmuir equation. The effect of temperature on the corrosion behavior in the presence of 10 -2 M of inhibitors was studied in the temperature range of 25-43 C. The associated activation energy of corrosion and other thermodynamic parameters have been determined. It has been found that all those schiff base compounds are excellent inhibitors. Obvious correlation was found between corrosion inhibition efficiency and quantum chemical parameters, using the linear and non-linear QSAR models. The obtained theoretical results have been compared with the experimental results.

  1. Experimental and theoretical spectroscopic study and structural determination of nickel(II) tridentate Schiff base complexes.

    PubMed

    Kianfar, Ali Hossein; Farrokhpour, Hossein; Dehghani, Parin; Khavasi, Hamid Reza

    2015-11-01

    Some new complexes of [NiL(PR3)] (where L=(E)-1-[(2-amino-5-nitrophenyl)iminio-methyl]naphthalene-2-olate (L(1)), (E)-1-[(2-hydroxiphenyl)iminio-methyl]naphthalene-2-olate (L(2)), R=Bu and Ph) containing tridentate ONN and ONO Schiff bases were synthesized and characterized by IR, UV-Vis, (1)H-NMR spectroscopy and elemental analysis. The geometry of [NiL(1)(PBu3)] and [NiL(2)(PBu3)] complexes were determined by X-ray crystallography. It was indicated that the complexes have a square planar structure and four coordinates in the solid state. Theoretical calculations were also performed to optimize the structures of the ligands and complexes in the gas phase and ethanol solvent, separately to confirm the structures proposed by X-ray crystallography. In addition, UV-Visible and IR spectra of the complexes were calculated and compared with the corresponding experimental spectra to complete the experimental structural identification. PMID:26051644

  2. Photoisomerization for a model protonated Schiff base in solution: Sloped/peaked conical intersection perspective

    SciTech Connect

    Malhado, Joao Pedro; Hynes, James T.

    2012-12-14

    The topographical character of conical intersections (CIs)-either sloped or peaked-has played a fundamental and important role in the discussion of the efficiency of CIs as photochemical 'funnels.' Here this perspective is employed in connection with a recent study of a model protonated Schiff base (PSB) cis to trans photoisomerization in solution [Malhado et al., J. Phys. Chem. A 115, 3720 (2011)]. In that study, the calculated reduced photochemical quantum yield for the successful production of trans product versus cis reactant in acetonitrile solvent compared to water was interpreted in terms of a dynamical solvent effect related to the dominance, for the acetonitrile case, of S{sub 1} to S{sub 0} nonadiabatic transitions prior to the reaching the seam of CIs. The solvent influence on the quantum yield is here re-examined in the sloped/peaked CI topographical perspective via conversion of the model's two PSB internal coordinates and a nonequilibrium solvent coordinate into an effective branching space description, which is then used to re-analyze the generalized Langevin equation/surface hopping results. The present study supports the original interpretation and enriches it in terms of topographical detail.

  3. His166 Is the Schiff Base Proton Acceptor in Attractant Phototaxis Receptor Sensory Rhodopsin I

    PubMed Central

    2015-01-01

    Photoactivation of attractant phototaxis receptor sensory rhodopsin I (SRI) in Halobacterium salinarum entails transfer of a proton from the retinylidene chromophores Schiff base (SB) to an unidentified acceptor residue on the cytoplasmic half-channel, in sharp contrast to other microbial rhodopsins, including the closely related repellent phototaxis receptor SRII and the outward proton pump bacteriorhodopsin, in which the SB proton acceptor is an aspartate residue salt-bridged to the SB in the extracellular (EC) half-channel. His166 on the cytoplasmic side of the SB in SRI has been implicated in the SB proton transfer reaction by mutation studies, and mutants of His166 result in an inverted SB proton release to the EC as well as inversion of the proteins normally attractant phototaxis signal to repellent. Here we found by difference Fourier transform infrared spectroscopy the appearance of Fermi-resonant XH stretch modes in light-minus-dark difference spectra; their assignment with 15N labeling and site-directed mutagenesis demonstrates that His166 is the SB proton acceptor during the photochemical reaction cycle of the wild-type SRIHtrI complex. PMID:25162914

  4. Crystal structures, spectroscopic and theoretical study of novel Schiff bases of 2-(methylthiomethyl)anilines

    NASA Astrophysics Data System (ADS)

    Olalekan, Temitope E.; Adejoro, Isaiah A.; VanBrecht, Bernardus; Watkins, Gareth M.

    2015-03-01

    New Schiff bases derived from p-methoxysalicylaldehyde and 2-(methylthiomethyl)anilines (substituted with methyl, methoxy, nitro) were synthesized and characterized by elemental analyses, FT-IR, NMR, electronic spectra and quantum chemical calculations. X-ray crystallography of two compounds showed the solid structures are stabilized by intramolecular and intermolecular H-bonds. The effect of OH⋯N interaction between the phenolic hydrogen and imine nitrogen on the proton and carbon NMR shifts, and the role of CH⋯O and CH⋯S contacts are discussed. The bond lengths and angles, 1H and 13C NMR data, ELUMO-HOMO, dipole moments and polarizability of the compounds were predicted by density functional theory, DFT (B3LYP/6-31G??) method. The experimental geometric parameters and the NMR shifts were compared with the calculated values, which gave good correlations. The electronic effects of aryl ring substituents (methyl, methoxy and nitro) on the properties of the resulting compounds, such as the color, NMR shifts, electronic spectra and the calculated energy band gaps, dipole moments and polarizability are discussed. Increase in electron density shifted the phenolic proton resonance to lower fields. The methoxy-substituted compound has a small dipole moment and subsequent large polarizability value. Highest polarity was indicated by the nitro compound which also showed high polarizability due to its larger size. The energy gaps obtained from ELUMO-HOMO calculations suggest these compounds may have applications as organic semiconducting materials.

  5. Colorimetric detection of in situ metal acetates and fluorides by a bipyridyl-linked Schiff base.

    PubMed

    Suganya, Sivalingam; Zo, Hye Jin; Park, Jong S; Velmathi, Sivan

    2014-12-01

    Here, we present a new bipyridyl moiety linked Schiff base (bipy-1) that is well characterized using spectroscopic techniques. Colorimetric and UV-vis titrations were used to study the photophysical properties of bipy-1 in the presence of various tetrabutyl ammonium salt of anions and metal salts containing different counter cations. bipy-1 showed selective recognition of dimethyl sulphoxide solution of tetrabutyl ammonium salt of F(-) ion accompanied with a UV-vis band at 529?nm and interesting binding of aqueous Co, Ni, and Cu acetates/fluorides, as confirmed by distinct color changes from fluorescent green to pink or orange and a strong band around 480-510?nm in the UV-vis spectrum. However, in the presence of Co, Ni, and Cu countercations, any form of metal acetate/fluorides was found to be able to respond to similar color changes from fluorescent green to pink or orange, showing a band around 480-510?nm. This type of output clearly indicates that the in situ formation of Co, Ni, and Cu acetates/fluorides also coordinates with bipyridyl nitrogen atoms. PMID:25319616

  6. Substituent effects on anion sensing of salicylidene Schiff base derivatives: Tuning sensitivity and selectivity.

    PubMed

    Zang, Libin; Jiang, Shimei

    2015-11-01

    A series of colorimetric anion sensors using the salicylidene Schiff bases with different substituents, including electron donating group (tert-butyl, in sensor 2), conjugated group (naphthyl, in sensor 3) and electron withdrawing group (chlorine, in sensor 4), respectively, have been developed. The substituents can not only impact chromogenic signal output, but also tune the sensitivity and selectivity of the anion sensing by their specific electron push-pull features. In particular, both 1 (without substituent) and 2 show high selectivity for F(-) over Cl(-), Br(-), I(-), AcO(-) and H2PO4(-), but the sensitivity of 2 is poorer than 1 due to the effect of electron donating groups. Sensor 3 exhibits higher sensitivity for F(-) than 1, but it is disturbed by the weak response to AcO(-) and H2PO4(-). Sensor 4 has the highest sensitivity for F(-), but shows the significant response to AcO(-) and H2PO4(-), which also decreases the selectivity for F(-). Finally, analytical applications of 1 for the detection of F(-) in aqueous medium and toothpaste have been studied. PMID:26112105

  7. Synthesis, structure and antidiabetic activity of chromium(III) complexes of metformin Schiff-bases

    NASA Astrophysics Data System (ADS)

    Mahmoud, M. A.; Zaitone, S. A.; Ammar, A. M.; Sallam, S. A.

    2016-03-01

    A series of Cr3+ complexes with Schiff-bases of metformin with each of salicylaldehyde (HL1); 2,3-dihydroxybenzaldehyde (H2L2); 2,4-dihydroxybenzaldehyde (H2L3); 2,5-dihydroxybenzaldehyde (H2L4); 3,4-dihydroxybenzaldehyde (H2L5) and 2-hydroxynaphthaldehyde (HL6) were synthesized by template reaction. The new compounds were characterized through elemental analysis, conductivity and magnetic moment measurements, IR, UV-Vis., NMR and mass spectroscopy. The complexes have octahedral structure with μ value of hexacoordinated chromium ion. TGA, DTG and DTA analysis confirm the proposed stereochemistry and a mechanism for thermal decomposition was proposed. Thermodynamic parameters are calculated for the second and third decomposition steps. [CrL4Cl(H2O)2].3H2O and [CrL5Cl(H2O)2].2½H2O were able to produce significant decreases in the blood glucose level.

  8. Synthesis of novel Schiff's bases of highly potential biological activities and their structure investigation

    NASA Astrophysics Data System (ADS)

    Zayed, Ehab M.; Zayed, M. A.

    2015-05-01

    Novel bisaldehyde-hydrazide Schiff's bases AS1 (2,2?-(ethane-1,2-diylbis(oxy))dibenzaldehyde terephthalohydrazide) and AS2 (N?,N??-(((ethane-1,2-diylbis(oxy))bis(2,1-phenylene))bis(methanylylidene))di(benzohydrazide)) were prepared as new macrocyclic compounds via condensation reactions. AS1 had been prepared by condensation between (2,2?-(ethane-1,2-diylbis(oxy))dibenzaldehyde) bisaldehyde and terephthalohydrazide in a ratio1:1. AS2 had been obtained by condensation between (2,2?-(ethane-1,2-diylbis(oxy))dibenzaldehyde) bisaldehyde and benzohydrazide in ratio 1:2. The structures of AS1 and AS2 were characterized by elemental analysis (EA), mass (MS), FT-IR and 1H-NMR spectra, and thermal analyses (TG, DTG). The activation thermodynamic parameters such as ?E?, ?H?, ?S? and ?G? were calculated from the TG curves using Coats-Redfern method. It is important to investigate their molecular structures to know the active groups and weak bonds responsible for their biological activities. Consequently in the present work, the obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculations (MOCS) using PM3 procedure. Their biological activities had been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillus subtilis and Staphylococcus aurous bacteria in order to assess their anti-microbial potential.

  9. Novel Organotin(IV) Schiff Base Complexes with Histidine Derivatives: Synthesis, Characterization, and Biological Activity.

    PubMed

    Garza-Ortiz, Ariadna; Camacho-Camacho, Carlos; Sainz-Espues, Teresita; Rojas-Oviedo, Irma; Gutirrez-Lucas, Luis Ral; Gutierrez Carrillo, Atilano; Vera Ramirez, Marco A

    2013-01-01

    Five novel tin Schiff base complexes with histidine analogues (derived from the condensation reaction between L-histidine and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) have been synthesized and characterized. Characterization has been completed by IR and high-resolution mass spectroscopy, 1D and 2D solution NMR ((1)H, (13)C??and (119)Sn), as well as solid state (119)Sn NMR. The spectroscopic evidence shows two types of structures: a trigonal bipyramidal stereochemistry with the tin atom coordinated to five donating atoms (two oxygen atoms, one nitrogen atom, and two carbon atoms belonging to the alkyl moieties), where one molecule of ligand is coordinated in a three dentate fashion. The second structure is spectroscopically described as a tetrahedral tin complex with four donating atoms (one oxygen atom coordinated to the metal and three carbon atoms belonging to the alkyl or aryl substituents), with one molecule of ligand attached. The antimicrobial activity of the tin compounds has been tested against the growth of bacteria in vitro to assess their bactericidal properties. While pentacoordinated compounds 1, 2, and 3 are described as moderate effective to noneffective drugs against both Gram-positive and Gram-negative bacteria, tetracoordinated tin(IV) compounds 4 and 5 are considered as moderate effective and most effective compounds, respectively, against the methicillin-resistant Staphylococcus aureus strains (Gram-positive). PMID:23864839

  10. Novel Organotin(IV) Schiff Base Complexes with Histidine Derivatives: Synthesis, Characterization, and Biological Activity

    PubMed Central

    Garza-Ortiz, Ariadna; Camacho-Camacho, Carlos; Sainz-Espues, Teresita; Rojas-Oviedo, Irma; Gutirrez-Lucas, Luis Ral; Gutierrez Carrillo, Atilano; Vera Ramirez, Marco A.

    2013-01-01

    Five novel tin Schiff base complexes with histidine analogues (derived from the condensation reaction between L-histidine and 3,5-di-tert-butyl-2-hydroxybenzaldehyde) have been synthesized and characterized. Characterization has been completed by IR and high-resolution mass spectroscopy, 1D and 2D solution NMR (1H, 13C??and 119Sn), as well as solid state 119Sn NMR. The spectroscopic evidence shows two types of structures: a trigonal bipyramidal stereochemistry with the tin atom coordinated to five donating atoms (two oxygen atoms, one nitrogen atom, and two carbon atoms belonging to the alkyl moieties), where one molecule of ligand is coordinated in a three dentate fashion. The second structure is spectroscopically described as a tetrahedral tin complex with four donating atoms (one oxygen atom coordinated to the metal and three carbon atoms belonging to the alkyl or aryl substituents), with one molecule of ligand attached. The antimicrobial activity of the tin compounds has been tested against the growth of bacteria in vitro to assess their bactericidal properties. While pentacoordinated compounds 1, 2, and 3 are described as moderate effective to noneffective drugs against both Gram-positive and Gram-negative bacteria, tetracoordinated tin(IV) compounds 4 and 5 are considered as moderate effective and most effective compounds, respectively, against the methicillin-resistant Staphylococcus aureus strains (Gram-positive). PMID:23864839

  11. Cobalt-Schiff base complex catalyzed oxidation of para-substituted phenolics. Preparation of benzoquinones

    SciTech Connect

    Bozell, J.J.; Hames, B.R.; Dimmel, D.R.

    1995-04-21

    Para-substituted phenolics, serving as models for lignin (a renewable source of carbon), are oxidized to the corresponding benzoquinone with oxygen in the presence of catalytic amounts of Co-Schiff base complexes. The reaction products observed depend on the structure of the catalyst. The 5-coordinate catalysts (pyridine)[bis(salicylidene)ethylenediamine]cobalt[(pyr)Co(salen)]and[bis(salicylideneamino)ethylamine]cobalt [Co(n-Me salpr)] convert syringyl alcohol (3,5-dimethoxy-4-hydroxybenzyl alcohol) to 2,6-dimethoxybenzoquinone in high yield. In contrast, syringaldehyde (3,5-dimethoxy-4-hydroxybenzaldehyde) is unreactive toward these catalysts. However, the 4-coordinate Co(salen) converts syringaldehyde to 2,6-dimethoxybenzoiquinone in 72% isolated yield. Phenols bearing a single methoxy group on the ring are unreactive toward any catalyst in MeOH. However, vanillyl alcohol (3-methoxy-4-hydroxybenzyl alcohol) is converted to 2-methoxybenzo-quinone with Co(N-Me salpr) and oxygen in 43% yield in CH{sub 2}Cl{sub 2} and 58% yield in CH{sub 2}Cl{sub 2} in the presence of 1% CuCl{sub 2}. The success of the oxidations appears to be related to the ease of removal of the phenolic hydrogen by the Co/O{sub 2} complex. Competitive deactivation of the catalyst occurs with substrates of lower reactivity. 84 tabs.

  12. Schiff Base Switch II Precedes the Retinal Thermal Isomerization in the Photocycle of Bacteriorhodopsin

    PubMed Central

    Wang, Ting; Facciotti, Marc T.; Duan, Yong

    2013-01-01

    In bacteriorhodopsin, the order of molecular events that control the cytoplasmic or extracellular accessibility of the Schiff bases (SB) are not well understood. We use molecular dynamics simulations to study a process involved in the second accessibility switch of SB that occurs after its reprotonation in the N intermediate of the photocycle. We find that once protonated, the SB C15 = NZ bond switches from a cytoplasmic facing (13-cis, 15-anti) configuration to an extracellular facing (13-cis, 15-syn) configuration on the pico to nanosecond timescale. Significantly, rotation about the retinal’s C13 = C14 double bond is not observed. The dynamics of the isomeric state transitions of the protonated SB are strongly influenced by the surrounding charges and dielectric effects of other buried ions, particularly D96 and D212. Our simulations indicate that the thermal isomerization of retinal from 13-cis back to all-trans likely occurs independently from and after the SB C15 = NZ rotation in the N-to-O transition. PMID:23922839

  13. Coordination geometry around copper in a Schiff-base trinuclear copper complex using EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Gaur, Abhijeet; Shrivastava, B. D.; Gaur, D. C.; Prasad, J.; Srivastava, K.; Jha, S. N.; Bhattacharyya, D.; Poswal, A.

    2012-05-01

    In the present investigation, we have studied extended X-ray absorption fine structure (EXAFS) spectra of a trinuclear Schiff-base copper complex tetraaqua-di-?3-(N-salicylidene-DL-glutamato)-tricopper(II)heptahydrate, [Cu3(C12H10NO5)2 (H2O)4]. 7H2O, in which three metal sites are present. One metal site is square-pyramidal (4+1) and other two similar metal sites are tetragonally distorted octahedral (4+2). EXAFS has been recorded at the K-edge of copper in the complex at the dispersive EXAFS beamline at 2 GeV Indus-2 synchrotron source at RRCAT, Indore, India. The analysis of EXAFS spectra of multinuclear metal complexes pose some problems due to the presence of many absorbing atoms, even when the absorbing atoms may be of the same element. Hence, using the available crystal structure of the complex, theoretical models have been generated for the different copper sites separately, which are then fitted to the experimental EXAFS data. The two coordination geometries around the copper sites have been determined. The contributions of the different copper sites to the experimental spectrum have been estimated. The structural parameters, which include bond-lengths, coordination numbers and thermal disorders, for the two types of copper sites have been reported. Further, copper has been found to be in +2 oxidation state at these metal sites.

  14. The resonance Raman profile of a nickel Schiff base complex at 10 K

    NASA Astrophysics Data System (ADS)

    Datta, M.; Brown, D. H.; Smith, W. E.

    The resonance Raman profile for the Schiff-base complex N,N'-bis(salicyladehyde)- o-diaminobenzene nickel (II) has been measured at 290 and 10 K and the main peaks assigned. A broad fluorescence with a maximum at ca. 672 nm reduced the sensitivity of some measurements at room temperature but at 10 K this band had shifted sufficiently to enable definitive Raman spectra to be recorded over the entire range of exciting lines used. A second sharper fluorescence was observed and in this case, the band position was dependent on the exciting line, occurring about 7.4 nm from it. More bands were observed in the resonance profile at 10 K than at room temperature, and two electronic transitions which were not resolved in the electronic spectra at either temperature were characterized. The lowest-energy electronic transitions are charge-transfer transitions between a ground state, which is largely composed of phenyl ring and oxygen orbitals and an excited state, composed mainly of oxygen and nickel orbitals. The electronic spectrum in the visible region is assigned on the basis of the resonance profile.

  15. Complexes of trivalent metal ions with potentially heptadentate N{sub 4}O{sub 3} Schiff base and amine phenol ligands of varying rigidity

    SciTech Connect

    Yang, L.W.; Liu, S.; Wong, E.; Rettig, S.J.; Orvig, C.

    1995-04-12

    The synthesis and characterization of several potentially heptadentate N{sub 4}O{sub 3} Schiff bases and amine phenols, as well as a series of their mononuclear and dinuclear complexes with indium and the lanthanides are reported. Schiff bases containing imidazolidine rings were the products of the known condensation reaction of triethylenetetramine with 3 equiv of 5-substituted salicylaldehydes to form H{sub 3}api (5-H-substituent), H{sub 3}Clapi (5-Cl-substituent), or H{sub 3}Brapi (5-Br-substituent); KBH{sub 4} reduction of these Schiff bases gave the appropriate isomeric N{sub 4}O{sub 3} amine phenols H{sub 3}(1,2,4-btt) and H{sub 3}(1,1,4-btt), as well as an acetone adduct, H{sub 3}(1,2,4-ahi). The Schiff bases reacted with 1 equiv of a lanthanide (Ln{sup 3+}) nitrate to produce mononuclear nine-coordinated [Ln(H{sub 3}Xapi)-(NO{sub 3}){sub 3}] complex wherein the ligand adopts a tridentate capping coordination mode, whereas the amine phenols formed mononuclear seven-coordinate complexes with the lanthanides and indium; homodinuclear complexes [LnL]{sub 2} were also obtained with the Schiff bases. The X-ray structures of the Schiff bases H{sub 3}api and H{sub 3}Clapi, the mononuclear amine phenol complexes Yb(1,2,4-btt){center_dot}0.5CH{sub 3}OH and In(1,1,4-btt), and the homodinuclear Schiff base complex [La(Brapi)]{sub 2}{center_dot}2CHCl{sub 3} have been determined.

  16. A high performance Schiff-base fluorescent probe for monitoring Au(3+) in zebrafish based on BODIPY.

    PubMed

    Wang, Enze; Pang, Lanfang; Zhou, Yanmei; Zhang, Junli; Yu, Fang; Qiao, Han; Pang, Xiaobin

    2016-03-15

    We designed and synthesized a mono-Schiff-base fluorescent probe (Probe 1) based on a boron-dipyrromethene (BODIPY) dye. By investigating the recognition of Au(3+) through an irreversible C=N bond hydrolysis reaction, Probe 1 exhibited higher properties such as acting as a "naked eye" probe, stability to pH, fast-response of 90s, a lower detection limit of 60 nM, stronger antijamming capability, and better live-cells imaging with low cytotoxicity compared with other probes. Even in relatively high temperatures, Probe 1 maintained its own excellent characteristic. More importantly, this is the first time that one chemosensor could be successfully applied to Au(3+) imaging in zebrafish, which demonstrated the performance that Probe 1 exhibited wonderful organism permeability. PMID:26513288

  17. Improved conditions for periodate/Schiff's base-based fluorescent staining of glycoproteins with dansylhydrazine in SDS-PAGE.

    PubMed

    Zhou, Xuan; Hong, Guo-Ying; Huang, Bin-Bin; Duan, Yuan-Meng; Shen, Jia-Yi; Ni, Mao-Wei; Cong, Wei-Tao; Jin, Li-Tai

    2014-05-01

    An improved periodate/Schiff's base based fluorescent stain with dansylhydrazine (DH) for glycoproteins in 1D and 2D SDS-PAGE was described. Down to 4-8ng of glycoproteins can be selectively detected within 2h, which is approximately 16-fold higher than that of original protocol, but similar to that of Pro-Q Emerald 488 stain (Invitrogen, Carlsbad, USA). Furthermore, subsequent study of deglycosylation, glycoprotein affinity isolation, and LC-MS/MS analysis were performed to confirm the specificity of the improved method. As a result, improved DH stain may provide a new choice for selective, economic, MS compatible, and convenient visualization of gel-separated glycoproteins. PMID:24591039

  18. New platinum and ruthenium Schiff base complexes for water splitting reactions.

    PubMed

    Wang, Chuanjun; Chen, Yong; Fu, Wen-Fu

    2015-08-28

    New platinum(ii) and ruthenium(ii) mononuclear complexes with naphthalene-based Schiff base ligands L1 (H2-selnaph) and L2 (H2-selnaph-COOH) were synthesized: Pt-selnaph (), Pt-selnaph-COOH (), Ru-selnaph(4-picoline)2 (), and Ru-selnaph(isoquinoline)2 (). The complexes were characterized by NMR spectroscopy, matrix-assisted laser desorption/ionization time-of-flight spectrometry, and elemental analysis, and their electrochemical and photophysical properties were investigated. The luminescent complexes and were used as photosensitizers for visible-light driven hydrogen production reactions in the presence of sacrificial electron donor triethylamine and cocatalyst precursor K2PtCl4 aqueous solution. When complex was attached to the surface of TiO2 by a carboxyl group, enhanced hydrogen photogeneration was achieved compared with complex alone, with turnover numbers of about 84 after 12 h irradiation. Calculations based on electrochemical and spectroscopic data also confirmed the feasibility of electron injection through the carboxyl group of complex into the conduction band of TiO2 for hydrogen production reactions. Complexes and were found to be efficient stable water oxidation (NH4)2Ce(NO3)6-driven catalysts with a first-order reaction behavior. A turnover frequency of 5.34 min(-1) was achieved for complex , while complex exhibited an enhanced turnover frequency of 11.9 min(-1) in pH 1.0 aqueous solution. Turnover numbers up to 1400 and 2060 were obtained after 6.5 h of reaction for and , respectively. Unique mechanistic information for water splitting is also presented through electrochemical, spectroscopic and ESI-MS high-valent ruthenium-oxo intermediate investigations. PMID:26205430

  19. A triazole Schiff base-based selective and sensitive fluorescent probe for Zn(2+): A combined experimental and theoretical study.

    PubMed

    Yuan, Caixia; Liu, Xinyu; Wu, Yanbo; Lu, Liping; Zhu, Miaoli

    2016-02-01

    A triazole-Schiff base, 4-(5-Chloro-2-hydroxybenzylideneamino)-1H-1,2,4-triazole-5(4H)-thione (HL), exhibits the high selectivity and sensitivity for Zn(2+) in the fluorescence spectrometry over other common metal ions, especially Cd(2+) in DMSO:H2O (1:9, v/v) solution. A 1:1 binding ratio of Zn(2+)/L for the complex has been obtained by Uv-Vis titration experiments and Job's plot with the detection limit of 51nmol/L. The coordination mode of the complex in solution was further confirmed by density functional theory (DFT) calculations. Time-dependent density functional theory (TD-DFT) calculations indicate that a chelation-enhanced fluorescence (CHEF) effect occurs in the process of detecting Zn ion. PMID:26529638

  20. A triazole Schiff base-based selective and sensitive fluorescent probe for Zn2 +: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Yuan, Caixia; Liu, Xinyu; Wu, Yanbo; Lu, Liping; Zhu, Miaoli

    2016-02-01

    A triazole-Schiff base, 4-(5-Chloro-2-hydroxybenzylideneamino)-1H-1,2,4-triazole-5(4H)-thione (HL), exhibits the high selectivity and sensitivity for Zn2 + in the fluorescence spectrometry over other common metal ions, especially Cd2 + in DMSO:H2O (1:9, v/v) solution. A 1:1 binding ratio of Zn2 +/L for the complex has been obtained by Uv-Vis titration experiments and Job's plot with the detection limit of 51 nmol/L. The coordination mode of the complex in solution was further confirmed by density functional theory (DFT) calculations. Time-dependent density functional theory (TD-DFT) calculations indicate that a chelation-enhanced fluorescence (CHEF) effect occurs in the process of detecting Zn ion.

  1. Co(II), Ni(II) and Cu(II) complexes with coumarin-8-yl Schiff-bases: Spectroscopic, in vitro antimicrobial, DNA cleavage and fluorescence studies

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Unki, Shrishila N.; Kulkarni, Ajaykumar D.; Naik, Vinod H.; Badami, Prema S.

    2011-09-01

    A new series of Co(II), Ni(II) and Cu(II) complexes of the type ML·2H 2O of Schiff-bases derived from m-substituted thiosemicarbazides and 8-acetyl-7-hydroxy-4-methylcoumarin have been synthesized and characterized by spectroscopic studies. Schiff-bases exhibit thiol-thione tautomerism wherein sulphur plays an important role in the coordination. The coordination possibility of the Schiff-bases towards metal ions have been proposed in the light of elemental analyses, spectral (IR, UV-vis, FAB-mass, ESR and fluorescence), magnetic and thermal studies. The low molar conductance values in DMF indicate that, the metal complexes are non-electrolytes. The cyclic voltammetric studies suggested that, the Cu(II) and Ni(II) complexes are of single electron transfer quasi-reversible nature. The Schiff-bases and its metal complexes have been evaluated for their in vitro antibacterial ( Escherichia coli, Staphilococcus aureus, Bascillus subtilis and Salmonella typhi) and antifungal activities ( Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The Schiff-base I and its metal complexes exhibited DNA cleavage activity on isolated DNA of A. niger.

  2. Electronic-structure and quantum dynamical study of the photochromism of the aromatic Schiff base salicylideneaniline

    SciTech Connect

    Ortiz-Sanchez, Juan Manuel; Gelabert, Ricard; Moreno, Miquel; Lluch, Jose M.

    2008-12-07

    The ultrafast proton transfer dynamics of salicylideneaniline has been theoretically analyzed in the ground and first singlet excited electronic states using density functional theory (DFT) and time-dependent DFT calculations, which predict a ({pi},{pi}*) barrierless excited state intramolecular proton transfer (ESIPT). In addition to this, the photochemistry of salicylideneaniline is experimentally known to present fast depopulation processes of the photoexcited species before and after the proton transfer reaction. Such processes are explained by means of conical intersections between the ground and first singlet ({pi},{pi}*) excited electronic states. The electronic energies obtained by the time-dependent density functional theory formalism have been fitted to a monodimensional potential energy surface in order to perform quantum dynamics study of the processes. Our results show that the proton transfer and deactivation of the photoexcited species before the ESIPT processes are completed within 49.6 and 37.7 fs, respectively, which is in remarkable good agreement with experiments.

  3. Orientation of the protonated retinal Schiff base group in bacteriorhodopsin from absorption linear dichroism.

    PubMed Central

    Lin, S W; Mathies, R A

    1989-01-01

    Linear dichroism experiments are performed on light-adapted bacteriorhodopsin (BR568) films containing native retinal (A1) and its 3,4-dehydroretinal (A2) analogue to measure the angle between the chromophore transition dipole moment and the membrane normal. QCFF/pi calculations show that the angle between the transition moment and the long axis of the polyene is changed by 3.4 degrees when the C3-C4 bond is unsaturated. The difference vector between the two transition moments points in the same direction as the Schiff base (N----H) bond for the all-trans BR568 chromophore. Because the plane of the chromophore is perpendicular to the membrane plane, a comparison of the transition moment orientations in the A1- and A2-pigments enables us to determine the orientation of the N----H bond with respect to the absolute chromophore (N----C5 vector) orientation. The angles of the transition moments are 70.3 degrees +/- 0.4 degrees and 67.8 degrees +/- 0.4 degrees for the A1- and A2-pigments, respectively. The fact that the change in the transition moment angle (2.5 degrees) is close to the predicted 3.4 degrees supports the idea that the chromophore plane is nearly perpendicular to the membrane plane. The decreased transition moment angle in the A2-analogue requires that the N----H bond and the N----C5 vector point toward the same membrane surface. Available results indicate that the N----C5 vector points toward the exterior in BR568. With this assignment, we conclude that the N----H bond points toward the exterior surface and its most likely counterion Asp-212. This information makes possible the construction of a computer graphics model for the active site in BR568. PMID:2819231

  4. Syntheses, crystal structure, Hirshfeld surfaces, fluorescence properties, and DFT analysis of benzoic acid hydrazone Schiff bases.

    PubMed

    Alam, Mohammad Sayed; Lee, Dong-Ung

    2015-06-15

    Two hydrazone Schiff base analogues, namely, (E)-N'-(4-hydroxy-3-methoxybenzylidene)benzohydrazide (3a) and (E)-N'-(4-methoxybenzylidene)benzohydrazide (3b), were synthesized using a mild, efficient method and characterized by (1)H NMR, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction. X-ray analysis of a single crystal of 3a revealed a tetragonal, space group I4(1)/a structure, with an E-configuration around the azomethine (C8N2) double bond. In this structure, the NH and OH groups act as proton donors and the >CO and N groups as proton acceptors, and these facilitate hydrogen bond formation in the crystal state. Plausible intermolecular interactions were studied using 3D Hirshfeld surfaces and related 2D fingerprint plots. The optimized geometry, vibrational frequencies, Mulliken charge distribution, molecular electrostatic potential (MEP) maps, frontier molecular orbitals (FMOs), and associated energies of the ground state and the first single excited state were calculated using density functional theory (DFT) and time-dependant DFT calculations using the B3LYP/6-311G method. Vibrational frequencies calculated in the gaseous phase compared with experimental values measured in the solid state and showed good agreement with each other. The chemical reactivities of 3a and 3b were predicted by mapping MEP surface over optimized geometries and comparing these with MEP map generated over crystal structures. Mulliken charge distribution analysis and MEP map of 3a and 3b revealed that N(1), O(1), O(2) and O(3) atoms could act as electron donors and coordinate with metals and that these represented the most suitable sites for electrophilic attack. In fluorescence spectra, the absorption and emission spectra of 3a and 3b were similar in different polar solvents with few exceptions. In addition, both compounds exhibited dual emission spectra in acetone due to keto-enol tautomerism induced by photoexcitation. PMID:25804368

  5. Syntheses, crystal structure, Hirshfeld surfaces, fluorescence properties, and DFT analysis of benzoic acid hydrazone Schiff bases

    NASA Astrophysics Data System (ADS)

    Alam, Mohammad Sayed; Lee, Dong-Ung

    2015-06-01

    Two hydrazone Schiff base analogues, namely, (E)-N?-(4-hydroxy-3-methoxybenzylidene)benzohydrazide (3a) and (E)-N?-(4-methoxybenzylidene)benzohydrazide (3b), were synthesized using a mild, efficient method and characterized by 1H NMR, mass spectrometry, elemental analysis, and single-crystal X-ray diffraction. X-ray analysis of a single crystal of 3a revealed a tetragonal, space group I4(1)/a structure, with an E-configuration around the azomethine (sbnd C8dbnd N2sbnd) double bond. In this structure, the sbnd NHsbnd and sbnd OH groups act as proton donors and the >Cdbnd O and sbnd Ndbnd groups as proton acceptors, and these facilitate hydrogen bond formation in the crystal state. Plausible intermolecular interactions were studied using 3D Hirshfeld surfaces and related 2D fingerprint plots. The optimized geometry, vibrational frequencies, Mulliken charge distribution, molecular electrostatic potential (MEP) maps, frontier molecular orbitals (FMOs), and associated energies of the ground state and the first single excited state were calculated using density functional theory (DFT) and time-dependant DFT calculations using the B3LYP/6-311G method. Vibrational frequencies calculated in the gaseous phase compared with experimental values measured in the solid state and showed good agreement with each other. The chemical reactivities of 3a and 3b were predicted by mapping MEP surface over optimized geometries and comparing these with MEP map generated over crystal structures. Mulliken charge distribution analysis and MEP map of 3a and 3b revealed that N(1), O(1), O(2) and O(3) atoms could act as electron donors and coordinate with metals and that these represented the most suitable sites for electrophilic attack. In fluorescence spectra, the absorption and emission spectra of 3a and 3b were similar in different polar solvents with few exceptions. In addition, both compounds exhibited dual emission spectra in acetone due to keto-enol tautomerism induced by photoexcitation.

  6. Manganese coordination chemistry of bis(imino)phenoxide derived [2 + 2] Schiff-base macrocyclic ligands.

    PubMed

    Yang, Wenxue; Zhao, Ke-Qing; Wang, Bi-Qin; Redshaw, Carl; Elsegood, Mark R J; Zhao, Jiang-Lin; Yamato, Takehiko

    2015-12-14

    The [2 + 2] Schiff-base macrocycles [2,2'-(CH2CH2)(C6H4N[double bond, length as m-dash]CH)2-2,6-(4-RC6H2OH)]2 ((R)H2), upon reaction with MnCl2 (two equivalents) afforded the bimetallic complex [Cl3Mn(?-Cl)Mn((Me)H2)] () or the salt complex [Cl3Mn(NCMe)][MnCl((tBu)H2)] (). Under similar conditions, use of the related [2 + 2] oxy-bridged macrocycle [2,2'-O(C6H4N[double bond, length as m-dash]CH)2-4-RC6H2OH] ((R)H2), afforded the bimetallic complexes [(MnCl)2(R)] (R = Me , tBu ), whilst the macrocycle derived from 1,2-diaminobenzene and 5,5'-di-tert-butyl-2,2'-dihydroxy-3,3'-methylenedibenzaldehyde (H4) afforded the complex [(MnCl)2()]2MeCN (2MeCN). For comparative studies, the salt complexes [2,6-(ArNHCH)2-4-MeC6H2O][MnCl3(NCMe)] (Ar = 2,4-Me2C6H3, ) and {[(2-ArN[double bond, length as m-dash]CH),6-(ArNHCH)-4-Me-C6H2O]MnCl}2[MnCl4]8CH2Cl2 (Ar = 4-MeC6H4, 8CH2Cl2) were prepared. The crystal structures of are reported (synchrotron radiation was necessary for complexes , and ). Complexes (not ) were screened for their potential to act as pre-catalysts for the ring opening polymerization (ROP) of ?-caprolactone; , and , were inactive, whilst and exhibited only poor activity with low conversion (<15%) at temperatures above 60 C. PMID:26596628

  7. A Schiff base derivative for effective treatment of diethylnitrosamine-induced liver cancer in vivo.

    PubMed

    Demirci, Selami; Do?an, Ay?egl; Ba?ak, Ne?e; Telci, Dilek; Dede, Blent; Orhan, Cemal; Tuzcu, Mehmet; ?ahin, Kazm; ?ahin, Nurhan; zercan, ?brahim Hanifi; ?ahin, Fikrettin

    2015-06-01

    Hepatocellular carcinoma is one of the most prevalent cancers, with a high morbidity rate, even in developed countries. In the present study, the curative effect of the Schiff base (SB) heterodinuclear copper(II)Mn(II) complex on diethylnitrosamine (DEN)-induced liver carcinoma was investigated. Hepatocarcinoma was initiated by an injection of DEN and promoted by phenobarbital (0.05%) in the diet. In addition, the potential nephrotoxicity of SB was evaluated in a cisplatin-induced nephrotoxicity model. Rats were administered the SB complex (1 and 2 mg/kg body weight/day) for 24 weeks, and cancer progression was investigated by macroscopic, histopathological, and western blot examinations. The administration of SB decreased the incidence and the number of hepatic nodules in a dose-dependent manner by regulating inflammation response and the apoptotic pathway. Western blot analyses from the livers of rats treated with SB after DEN induction showed significantly enhanced Bax and caspase-3 levels, with a marked decrease in the levels of Bcl-2, NF-?B p65 and cyclooxygenase (COX)-2. Results from the nephrotoxicity study showed that, whereas cisplatin increased serum urea nitrogen and creatinine levels, no increase in serum biochemical parameters was detected in SB-treated animals. Moreover, protein levels of NF-E2-related factor-2 (Nrf2) and heme oxygenase-1 were lower, whereas nuclear factor-?B (NF-?B p65) and activator protein-1 levels were higher in the kidneys of cisplatin-treated animals compared with that of the SB groups. Therefore, the SB complex could be an alternative chemotherapeutic option for liver cancer treatment once its safety in clinical applications has been examined. PMID:25714251

  8. Theoretical spectroscopic study of seven zinc(II) complex with macrocyclic Schiff-base ligand

    NASA Astrophysics Data System (ADS)

    Sayin, Koray; Kariper, Sultan Erkan; Sayin, Tuba Alagz; Karaka?, Duran

    2014-12-01

    Seven zinc complexes, which are [ZnL1]2+, [ZnL2]2+, [ZnL3]2+, [ZnL4]2+, [ZnL5]2+, [ZnL6]2+ and [ZnL7]2+, are studied as theoretically. Structural parameters, vibration frequencies, electronic absorption spectra and 1H and 13C NMR spectra are obtained for Zn(II) complexes of macrocyclic penta and heptaaza Schiff-base ligand. Vibration spectra of Zn(II) complexes are studied by using Density Functional Theory (DFT) calculations at the B3LYP/LANL2DZ. The UV-VIS and NMR spectra of the zinc complexes are obtained by using Time Dependent-Density Functional Theory (TD-DFT) method and Giao method, respectively. The agreements are found between experimental data of [ZnL5]2+, [ZnL6]2+ and [ZnL7]2+ complex ions and their calculated results. The geometries of complexes are found as distorted pentagonal planar for [ZnL1]2+, [ZnL2]2+ and [ZnL3]2+ complex ions, distorted tetrahedral for [ZnL4]2+ complex ion and distorted pentagonal bipyramidal for [ZnL5]2+, [ZnL6]2+ and [ZnL7]2+ complex ions. Ranking of biological activity is determined by using quantum chemical parameters and this ranking is found as: [ZnL7]2+ > [ZnL6]2+ > [ZnL5]2+ > [ZnL3]2+ > [ZnL2]2+ > [ZnL1]2+.

  9. Synthesis, characterization, DNA binding, DNA cleavage and antimicrobial studies of Schiff base ligand and its metal complexes.

    PubMed

    Mendu, Padmaja; Kumari, C Gyana; Ragi, Rajesh

    2015-03-01

    A series of Cu(II), Ni(II), Co(II), Mn(II) and Zn(II) complexes have been synthesized from the Schiff base ligand L. The Schiff base ligand 4-chloro-2-((4-oxo-4H-chromen-3yl) methylene amino) benzoic acid (L) has been synthesized by the reaction between chromone-3-carbaldehyde and 4-chloro-2-amino benzoic acid. The nature of bonding and geometry of the transition metal complexes as well as ligand L have been deduced from elemental analysis, FT-IR, UV-vis, (1)H NMR, (13)C NMR, ESR spectral studies, mass, magnetic susceptibility and molar conductance measurements. The complexes are found to have ML2 composition and are neutral in DMSO. Based on elemental, conductance and spectral studies, six-coordinated geometry was assigned for these complexes. The ligand L acts as tridentate and coordinates through nitrogen atom of azomethine group, hydroxyl of the carboxyl group and oxygen atom of keto group of ?-pyrone ring. The interaction of Cu(II) complex with CT-DNA was carried out by UV-vis, fluorescence titrations and viscosity measurements. The complex binds to DNA through intercalative binding mode. The nuclease activity of the above metal complexes shows that Cu(II) and Co(II) complexes cleave DNA through redox chemistry. The biological activity of the ligand and its complexes have been studied on four bacteria E. coli, B. subtilis, pseudomonas and Edwardella and two fungi penicillium and trichoderma by well disc and fusion method and found that the metal complexes are more active than the free Schiff base ligand. PMID:25663196

  10. A theoretical investigation into the luminescent properties of d8-transition-metal complexes with tetradentate Schiff base ligands.

    PubMed

    Tong, Glenna So Ming; Chow, Pui Keong; To, Wai-Pong; Kwok, Wai-Ming; Che, Chi-Ming

    2014-05-19

    A theoretical investigation on the luminescence efficiency of a series of d(8) transition-metal Schiff base complexes was undertaken. The aim was to understand the different photophysics of [M-salen](n) complexes (salen = N,N'-bis(salicylidene)ethylenediamine; M = Pt, Pd (n = 0); Au (n = +1)) in acetonitrile solutions at room temperature: [Pt-salen] is phosphorescent and [Au-salen](+) is fluorescent, but [Pd-salen] is nonemissive. Based on the calculation results, it was proposed that incorporation of electron-withdrawing groups at the 4-position of the Schiff base ligand should widen the (3)MLCT-(3)MC gap (MLCT = metal-to-ligand charge transfer and MC = metal centered, that is, the dd excited state); thus permitting phosphorescence of the corresponding Pd(II) Schiff base complex. Although it is experimentally proven that [Pd-salph-4E] (salph = N,N'-bis(salicylidene)-1,2-phenylenediamine; 4E means an electron-withdrawing substituent at the 4-position of the salicylidene) displays triplet emission, its quantum yield is low at room temperature. The corresponding Pt(II) Schiff base complex, [Pt-salph-4E], is also much less emissive than the unsubstituted analogue, [Pt-salph]. Thus, a detailed theoretical analysis of how the substituent and central metal affected the photophysics of [M-salph-X] (X is a substituent on the salph ligand, M = Pt or Pd) was performed. Temperature effects were also investigated. The simple energy gap law underestimated the nonradiative decay rates and was insufficient to account for the temperature dependence of the nonradiative decay rates of the complexes studied herein. On the other hand, the present analysis demonstrates that inclusions of low-frequency modes and the associated frequency shifts are decisive in providing better quantitative estimates of the nonradiative decay rates and the experimentally observed temperature effects. Moreover, spin-orbit coupling, which is often considered only in the context of radiative decay rate, has a significant role in determining the nonradiative rate as well. PMID:24715418

  11. The luminescent properties and toxicity controllability investigation of novel ZnO quantum dots with Schiff base complexes modification.

    PubMed

    Yu, Shi Yong; Jing, Hui; Cao, Zhen; Su, Hai Quan

    2014-05-01

    The Schiff base complexes modified ZnO quantum dots (ZnO-SBC QDs) are successfully synthesized via the reflux and chemical co-precipitation route. For control experiments, we also synthesized the ZnO QDs and amino-modified ZnO QDs (ZnO-NH2 QDs). The structures and morphologies of the samples were characterized via X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), FTIR spectroscopy (IR), Fluorescence Spectrometer (FL) and so on. The XRD pattern shows that the three types of QDs possess hexagonal wurtzite structures. The TEM investigation reveals that the as-prepared products have hexagonal morphologies. The plane fringe with 0.26 nm crystalline plane spacing of three types of quantum dots is assigned to the ZnO {002} planes via HR-TEM, which match with the lattice parameter of the hexagonal wurtzite structure of ZnO and also coincide with the data obtained by XRD. By analyzing the fluorescence emission and excitation spectra of ZnO QDs, ZnO-NH2 QDs, ZnO-SBC QDs and Schiff base complexes, we find that the ZnO-SBC QDs still have a perfect fluorescence emission which makes it interesting candidates for luminescence applications such as biochemical sensors and fluorescent labels to mark the cells and DNA. This novel ZnO-SBC QDs under UV irradiation is capable of generating reactive oxygen species by UV irradiation and may be used for the photodynamic therapy. The surface modification with Schiff base complexes makes it difficult to release Zn2+, therefore the toxicity is much more controllable. PMID:24734544

  12. Synthesis, spectroscopic identification, thermal, potentiometric and antibacterial activity studies of 4-amino-5-mercapto-S-triazole Schiff's base complexes

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Zayed, Mohamed E.; Alharbi, Suliman A.; Ammar, Reda A. A.; Chinnathambi, Arunachalam

    2015-05-01

    Complexes of manganese(II), cobalt(II), nickel(II), copper(II) and zinc(II) of general composition [M(L)2] have been synthesized [L = 4-pyridin-2-yl-methylene amino-4H-1,2,4-triazole-3-thiol]. The elemental analyses, molar conductance, spectral (IR, UV-Vis, 1H NMR, mass), magnetic moment and thermal measurements studies of the compounds led to the conclusion that the ligand acts as a tridentate manner (SNN). The molar conductance of the metal complexes in fresh solution of DMSO lies in the range of 8.34-10.46 ?-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of analytical and spectroscopic techniques, octahedral geometry of the complexes was proposed. The Schiff base acts as tridentate ligand coordinated through deprotonated thiolic sulfur, azomethine nitrogen and pyridine nitrogen atoms. The ligand field parameters were calculated for Co(II), Ni(II) and Cu(II) complexes and their values were found in the range reported for a octahedral structure. The data show that the complexes have composition of ML2 type. The activation of thermodynamic parameters are calculated using Coast-Redfern, Horowitz-Metzger (HM), Piloyan-Novikova (PN) and Broido's equations. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 C and ionic strength 0.10 M potassium nitrate. Both the Schiff's base ligand and its complexes have been screened for antibacterial activities.

  13. Design of chiral urea-quaternary ammonium salt hybrid catalysts for asymmetric reactions of glycine Schiff bases

    PubMed Central

    Tiffner, Maximilian; Novacek, Johanna; Busillo, Alfonso; Gratzer, Katharina; Massa, Antonio; Waser, Mario

    2015-01-01

    Bifunctional chiral urea-containing quaternary ammonium salts can be straightforwardly synthesised in good yield and with high structural diversity via a scalable and operationally simple highly telescoped sequence starting from trans-1,2-cyclohexanediamine. These novel hybrid catalysts were systematically investigated for their potential to control glycine Schiff bases in asymmetric addition reactions. It was found that Michael addition reactions and the herein presented aldol-initiated cascade reaction can be carried out to provide enantiomeric ratios up to 95 : 5 and good yields under mild conditions at room temperature. PMID:26504516

  14. Synthesis, characterization, crystal structures, computational studies, and antibacterial activities of two new Schiff bases derived from isophthalaldehyde

    NASA Astrophysics Data System (ADS)

    Salehi, Mehdi; Amoozadeh, Ali; Salamatmanesh, Arefe; Kubicki, Maciej; Dutkiewicz, Grzegorz; Samiee, Sepideh; Khaleghian, Ali

    2015-07-01

    Two new Schiff bases, N,N‧-(1,3-phenylenebis(methanylylidene))bis(4-bromoaniline) (1) and N,N‧-(1,3-phenylenebis(methanylylidene))bis(4-methoxyaniline) (2), have been synthesized by the reaction between isophthalaldehyde and appropriate aniline derivatives, and characterized by physico-chemical and spectroscopic methods. The structures of new compounds 1 and 2 have been characterized crystallographically. Moreover, structural optimization by DFT calculations have been performed and compared with the experimental data. The compounds were also screened for in vitro antibacterial activities against four human pathogenic bacteria and their minimum inhibitory concentrations showed moderate antibacterial activities.

  15. Synthesis, Characterization and Biological Properties of Anions of Bivalent Transition Metal [Co(II) and Ni(II)] Complexes With Acylhydrazine Derived ONO Donor Schiff Bases

    PubMed Central

    Farooq, M. A.; Iqbal, M. S.

    2000-01-01

    Some acylhydrazine derived ONO donor Schiff bases and their Co(II) and Ni(II) complexes have been prepared having the same metal ion (cation) but different anions. These synthesized metal(II) complexes have been characterized on the basis of their elemental analyses, magnetic moment, molar conductance, and IR and electronic spectral data. All of the Schiff base ligands function as tridentates and the deprotonated enolic form is preferred for coordination. In order to evaluate the effect of anions on the bactericidal activity, these synthesized complexes, in comparison to the uncomplexed Schiff bases have been screened against bacterial species., Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and the results are reported. PMID:18475936

  16. Analysis of the factors that influence the C=N stretching frequency of polyene Schiff bases. Implications for bacteriorhodopsin and rhodopsin.

    PubMed Central

    Gilson, H S; Honig, B H; Croteau, A; Zarrilli, G; Nakanishi, K

    1988-01-01

    In this study quantum mechanical calculations of force constants and normal mode analysis are used to elucidate the factors that influence the C=C and C=N stretching frequencies in polyenes and in protonated Schiff bases. The C=N stretching frequency is found to depend on both the C=N stretching force constant and the C=N-H bending force constant. Due to the contributions of these two modes, the C=N stretching frequency is particularly sensitive to the magnitude of the Schiff base counterion interactions and to the hydrogen bonding environment of the Schiff base nitrogen. Models for chromophore-protein interactions in the retinal binding site and for the photochemical transformations of bacteriorhodopsin and rhodopsin are evaluated in light of these results. PMID:3345334

  17. Homo dinuclear lanthanide(III) complexes of a mesogenic Schiff-base, N, N'-di-(4-decyloxysalicylidene)-1',6'-diaminohexane: Synthesis and characterization

    NASA Astrophysics Data System (ADS)

    Shakya, Pawan Raj; Singh, Angad Kumar; Rao, T. R.

    2011-09-01

    A mesogenic Schiff-base, N, N'-di-(4-decyloxysalicylidene)-1',6'-diaminohexane, H 2ddsdh (abbreviated as H 2L 2) that exhibits smectic-B ( SmB) mesophase, was synthesized and its structure studied by elemental analysis, mass spectrometry, NMR & IR spectral techniques. The Schiff-base, H 2L 2, upon condensation with hydrated lanthanide(III) nitrates, yields Ln III complexes of the general composition [Ln 2(L 2H 2) 3(NO 3) 4](NO 3) 2, where Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Ho. IR and NMR spectral data imply a bi-dentate bonding of the Schiff-base in its zwitterionic form (as L 2H 2) to the Ln III ions through two phenolate oxygens. The POM and DSC studies reveal that none of the Ln III complexes exhibits mesomorphism. Fluorescence studies show that the Tb III complex displays characteristic metal-centered fluorescence (solution state).

  18. Design of nanostructures based on aromatic peptide amphiphiles.

    PubMed

    Fleming, Scott; Ulijn, Rein V

    2014-12-01

    Aromatic peptide amphiphiles are gaining popularity as building blocks for the bottom-up fabrication of nanomaterials, including gels. These materials combine the simplicity of small molecules with the versatility of peptides, with a range of applications proposed in biomedicine, nanotechnology, food science, cosmetics, etc. Despite their simplicity, a wide range of self-assembly behaviours have been described. Due to varying conditions and protocols used, care should be taken when attempting to directly compare results from the literature. In this review, we rationalise the structural features which govern the self-assembly of aromatic peptide amphiphiles by focusing on four segments, (i) the N-terminal aromatic component, (ii) linker segment, (iii) peptide sequence, and (iv) C-terminus. It is clear that the molecular structure of these components significantly influences the self-assembly process and resultant supramolecular architectures. A number of modes of assembly have been proposed, including parallel, antiparallel, and interlocked antiparallel stacking conformations. In addition, the co-assembly arrangements of aromatic peptide amphiphiles are reviewed. Overall, this review elucidates the structural trends and design rules that underpin the field of aromatic peptide amphiphile assembly, paving the way to a more rational design of nanomaterials based on aromatic peptide amphiphiles. PMID:25199102

  19. Synthesis, spectral characterization, thermal analysis, molecular modeling and antimicrobial activity of new potentially N2O2 azo-dye Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Ammar, Yousry A.; Bayoumi, Hoda A.; Aldhlmani, Sharah A.

    2014-09-01

    The azo-dye Schiff's base of N2O2 dibasic ligand, H2L [N,N?-bis(5-(4-sulfanilamidophenylazosalicylidene)ethylenediamine] was prepared by the condensation of ethylenediamine with [5-(4-sulfanilamidophenylazo-salicylaldehyde] in ethanol. New complexes of with metal ions Cu(II), Ni(II), Co(II), Mn(II), Zn(II), Cd(II), Pt(IV), Fe(III) and Cr(III) are synthesized. Elemental, spectroscopic and thermal analyses as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. The azo-dye Schiff's base behaves as a di-negative N2O2 tetradentate ligand. The metal complexes exhibited square planar, tetrahedral and octahedral geometrical arrangements, the molar conductivity data indicates that all complexes are neutral. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the Cu(II), Mn(II), Cr(III) and Co(II) complexes were carried out in the range of 30-800 C. The complexes were decomposed in one and two stages of the Cu(II), Mn(II), Cr(III) and Co(II) complexes, respectively. Also, decomposition of the synthesized complexes is related to the Schiff's base characteristics. The thermal decomposition of the studied reactions was first order. The kinetic parameters for the decomposition steps in Cu(II), Mn(II), Cr(III) and Co(II) complexes thermograms have been calculated using Broido's method. In molecular modeling the geometries of azo-dye Schiff base ligand H2L and its metal(II/III/IV) complexes were fully optimized with respect to the energy using the 6-31G basis set. Antimicrobial activities of the azo-dye Schiff's base ligand and its corresponding metal complexes were screened against various organisms. The azo-dye Schiff's base ligand and some of its complexes were found to be biologically inactive.

  20. Synthesis, crystal structures, and spectral characterization of tetranuclear Mn(II) complex with a new Schiff base ligand and molecular dynamics studies on inhibition properties of such Schiff base

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Liu, Zheng; Yuan, Shuai; Liu, Jin

    2013-04-01

    A new Schiff base ligand H2L (3,5-dibromosalicylaldehyde pyridine-2-formyl hydrazone) and a new tetra-nuclear coordination complex [Mn4(L)4(DMF)4] (1) have been synthesized and characterized by spectral method (IR), fluorescence spectra, and elemental analysis. Structural characterization of the complex has been done by single-crystal X-ray diffraction analysis. Structural analysis reveals that the metal centers in complex [Mn4(L)4(DMF)4](1) exhibit distorted tetragonal-bipyramid coordination geometry, and each metal ion is coordinated by two mutually perpendicular Schiff base ligands (H2L) and one solvent DMF. The molecular dynamics (MDs) simulations method was performed to study the adsorption behavior of the H2L molecules on metal surface. The results show that the H2L molecules could adsorb on the metal surface firmly through several reactive sites. The analysis of pair correlation functions indicates that chemical bonds are formed between the oxygen nitrogen atoms of H2L molecules and the Fe atoms of Fe surface. These cause the result that H2L molecules interact with metal surface strongly and therefore have excellent corrosion inhibition performance.

  1. A spectroscopic investigation of the Schiff base reprotonation mechanism of bacteriorhodopsin

    NASA Astrophysics Data System (ADS)

    Russell, Terence Stephen

    This thesis reports time-resolved visible spectroscopy experiments performed on the light-driven proton pumping protein, bacteriorhodopsin (bR), and a number of artificially produced analogs. These analogs comprise a variety of single and double amino acid substitutions produced in several of the residues previously implicated in proton transport in bR. Also addressed are the results of resonance Raman and FTIR difference spectroscopy which provide information about the vibrational modes of the protein. The results from these experiments confirm aspects of both structural and functional models of bR based on previous electron diffraction and spectroscopic data. During a phase of the proton pumping photocycle in bR known as Schiff base reprotonation (also referred to as M intermediate decay), a proton is transferred over a 12 A distance from a proton donor residue (Asp-96) to the light-absorbing active site. The behavior of the M intermediate was monitored by time-resolved visible spectroscopy. In the single substitution known as D96N, the Asp-96 residue was replaced with a less efficient proton donor, asparagine. This mutant exhibited an M intermediate which decayed slowly in comparison to that of wild-type bR. However, this effect was reversed with the double substitution, T46D/D96N. This result indicates that the proton donor group can be moved to another nearby location and still yield a system functionally similar to the native protein. Replacement of the donor group with a histidine, His-96, resulted in a photocycle similar to D96N above pH 7. However, below this pH, the M intermediate is not detected. FTIR difference spectroscopy indicates that the protonation state of the substituted His-96 residue influences the structure of the active site of bR which suggests that a proton that is associated with His-96 may move towards the active site and thereby block M intermediate formation. Finally, the residue Thr-89 was replaced with an asparagine. This substitution altered not only the vibrational modes of the protein but also its visible absorption, which indicates that Thr-89 interacts directly with the active site of bR. These results are used to correct and extend an overall molecular model of the proton transport mechanism in bacteriorhodopsin.

  2. A new MoVI Schiff base complex: methanol[N?-(3-methoxy-2-oxidobenzylidene)benzohydrazidato]dioxidomolybdenum(VI)

    PubMed Central

    Sheikhshoaie, Iran; Langer, Vratislav; Yasrebi, Seyed Ali

    2011-01-01

    In the title benzilidene Schiff base molybdenum(VI) complex, [Mo(C15H12N2O3)O2(CH3OH)], the MoVI ion is coordinated by two oxide O atoms and by two O atoms and one N atom of the tridentate N?-(3-methoxy-2-oxidobenzylidene)benzohydrazidate (L) Schiff base ligand. The methanol O atom completes the distorted octahedral configuration of the MoVI atom. Strong OH?N hydrogen bonds form a C(5) chain around a 21 screw axis. Weak CHO hydrogen bonds are also present. PMID:21836845

  3. Synthesis and spectroscopic studies of some transition metal complexes of a novel Schiff base ligands derived from 5-phenylazo-salicyladehyde and o-amino benzoic acid

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; El-Deen, Ibrahim M.; Ibrahim, Hassan K.; El-Ghool, Samir

    2006-12-01

    Cu(II), Mn(II), Ni(II), and Zn(II) metal complexes with novel heterocyclic Schiff base derived from 5-phenyl azo-salicyladehyde and o-amino benzoic acid have been synthesized and characterized on the basis of elemental analyses, electronic, IR, and 1H NMR spectra, and also by aid of scanning electron microscopy (SEM), X-ray powder diffraction, molar ratio measurements, molar conductivity measurements, and thermogravimetric analyses. It has been found that the Schiff base behaves as neutral tridentate (ONO) ligand forming chelates with 1:1 (metal:ligand) stoichiometry.

  4. Affinity to bovine serum albumin and anticancer activity of some new water-soluble metal Schiff base complexes

    NASA Astrophysics Data System (ADS)

    Asadi, Mozaffar; Asadi, Zahra; Zarei, Leila; Sadi, Somaye Barzegar; Amirghofran, Zahra

    2014-12-01

    Metal Schiff-base complexes show biological activity but they are usually insoluble in water so four new water-soluble metal Schiff base complexes of Na2[M(5-SO3-1,2-salben]; (5-SO3-1,2-salben denoted N,N";-bis(5-sulphosalicyliden)-1,2-diaminobenzylamine and M = Mg, Mn, Cu, Zn) were synthesized and characterized. The formation constants of the metal complexes were determined by UV-Vis absorption spectroscopy. The interaction of these complexes with bovine serum albumin (BSA) was studied by fluorescence spectroscopy. Type of quenching, binding constants, number of binding sites and binding stoichiometries were determined by fluorescence quenching method. The results showed that the mentioned complexes strongly bound to BSA. Thermodynamic parameters indicated that hydrophobic association was the major binding force and that the interaction was entropy driven and enthalpically disfavoured. The displacement experiment showed that these complexes could bind to the subdomain IIA (site I) of albumin. Furthermore the synchronous fluorescence spectra showed that the microenvironment of the tryptophan residues was not apparently changed. Based on the Frster theory of non-radiation energy transfer, the distance between the donor (Trp residues) and the acceptor metal complexes was obtained. The growth inhibitory effect of complexes toward the K562 cancer cell line was measured.

  5. Synthesis, solvatochromaticity and bioactivities of some transition metal complexes with 2-(R-benzylideneamino)-pyridin-3-ol Schiff base derivatives

    NASA Astrophysics Data System (ADS)

    Ahmed, I. S.; Kassem, M. A.

    2010-10-01

    New four Schiff bases are prepared by condensation of 2-amino-pyridin-3-ol with 3, 4-dihydroxy-benzaldehyde (I), 2-hydroxybenzaldehyde (II), 5-bromo-2-hydroxybenzaldehyde (III), and 4-dimethylaminobenzaldehyde (IV). The structures of these compounds are characterized based on elemental analyses (C. H. N), IR and 1H NMR. Also, the electronic absorption spectra are recorded in organic solvents of different polarity. The solvents are selected to be covered a wide range of parameters (refractive index, dielectric constant and hydrogen bonding capacity). The UV-vis absorption spectra of Schiff base compounds are investigated in aqueous buffer solutions of varying pH and utilized for the determination of ionization constant, p Ka and activation free energy, Δ G* of the ionization process. The biological activity against bacterial species and fungi as microorganisms representing different microbial categories such as (two Gram-negative bacteria, Eschericha coli and Agrobacterium sp.),three Gram-positive bacteria ( Staphylococcus aureus, Bacillus subtlus and Bacillus megatherium), yeast ( Candida albicans), and fungi ( Aspergillus niger) were studied.

  6. Synthesis, structural, thermal studies and biological activity of a tridentate Schiff base ligand and their transition metal complexes

    NASA Astrophysics Data System (ADS)

    Abd El-halim, Hanan F.; Omar, M. M.; Mohamed, Gehad G.

    2011-01-01

    Schiff base (L) ligand is prepared via condensation of pyridine-2,6-dicarboxaldehyde with -2-aminopyridine. The ligand and its metal complexes are characterized based on elemental analysis, mass, IR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG and DTA). The molar conductance reveals that all the metal chelates are non-electrolytes. IR spectra shows that L ligand behaves as neutral tridentate ligand and bind to the metal ions via the two azomethine N and pyridine N. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral (Cr(III), Fe(III), Co(II), Ni(II), Cu(II), and Th(IV)) and tetrahedral (Mn(II), Cd(II), Zn(II), and UO 2(II)). The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ? H*, ? S* and ? G* are calculated from the DTG curves using Coats-Redfern method. The synthesized ligand, in comparison to their metal complexes also was screened for its antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi ( Candida). The activity data shows that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.

  7. Magnetostructural studies on ferromagnetically coupled copper(II) cubanes of Schiff-base ligands.

    PubMed

    Mukherjee, Arindam; Raghunathan, Rajamani; Saha, Manas K; Nethaji, Munirathinam; Ramasesha, Suryanarayanasastry; Chakravarty, Akhil R

    2005-05-01

    Three cubane copper(II) clusters, namely [Cu(4)(HL')4] (1), [Cu4L2(OH)2] (2), and [Cu4L2(OMe)2] (3), of two pentadentate Schiff-base ligands N,N'-(2-hydroxypropane-1,3-diyl)bis(acetylacetoneimine) (H3L') and N,N'-(2-hydroxypropane-1,3-diyl)bis(salicylaldimine) (H3L), are prepared, structurally characterized by X-ray crystallography, and their variable-temperature magnetic properties studied. Complex 1 has a metal-to-ligand stoichiometry of 1:1 and it crystallizes in the cubic space group P43n with a structure that consists of a tetranuclear core with metal centers linked by a mu(3)-alkoxo oxygen atom to form a cubic arrangement of the metal and oxygen atoms. Each ligand displays a tridentate binding mode which means that a total of eight pendant binding sites remain per cubane molecule. Complexes [Cu4L2(OH)2] (2) and [Cu4L2(OMe)2] (3) crystallize in the orthorhombic space group Pccn and have a cubane structure that is formed by the self-assembly of two {Cu2L}+ units. The variable-temperature magnetic susceptibility data in the range 300-18 K show ferromagnetic exchange interactions in the complexes. Along with the ferromagnetic exchange pathway, there is also a weak antiferromagnetic exchange between the copper centers. The theoretical fitting of the magnetic data gives the following parameters: J1 = 38.5 and J2 = -18 cm(-1) for 1 with a triplet (S = 1) ground state and quintet (S = 2) lowest excited state; J1 = 14.7 and J2 = -18.4 cm(-1) for 2 with a triplet ground state and singlet (S = 0) lowest excited state; and J1 = 33.3 and J2 = -15.6 cm(-1) for 3 with a triplet ground state and quintet lowest excited state, where J1 and J2 are two different exchange pathways in the cubane {Cu4O4} core. The crystal structures of 2 * 6 H2O and 3 * 2 H2O * THF show the presence of channels containing the lattice solvent molecules. PMID:15770710

  8. Retinal Chromophore Structure and Schiff Base Interactions in Red-Shifted Channelrhodopsin-1 from Chlamydomonas augustae

    PubMed Central

    2015-01-01

    Channelrhodopsins (ChRs), which form a distinct branch of the microbial rhodopsin family, control phototaxis in green algae. Because ChRs can be expressed and function in neuronal membranes as light-gated cation channels, they have rapidly become an important optogenetic tool in neurobiology. While channelrhodopsin-2 from the unicellular alga Chlamydomonas reinhardtii (CrChR2) is the most commonly used and extensively studied optogenetic ChR, little is known about the properties of the diverse group of other ChRs. In this study, near-infrared confocal resonance Raman spectroscopy along with hydrogen–deuterium exchange and site-directed mutagenesis were used to study the structure of red-shifted ChR1 from Chlamydomonas augustae (CaChR1). These measurements reveal that (i) CaChR1 has an all-trans-retinal structure similar to those of the light-driven proton pump bacteriorhodopsin (BR) and sensory rhodopsin II but different from that of the mixed retinal composition of CrChR2, (ii) lowering the pH from 7 to 2 or substituting neutral residues for Glu169 or Asp299 does not significantly shift the ethylenic stretch frequency more than 1–2 cm–1 in contrast to BR in which a downshift of 7–9 cm–1 occurs reflecting neutralization of the Asp85 counterion, and (iii) the CaChR1 protonated Schiff base (SB) has stronger hydrogen bonding than BR. A model is proposed to explain these results whereby at pH 7 the predominant counterion to the SB is Asp299 (the homologue to Asp212 in BR) while Glu169 (the homologue to Asp85 in BR) exists in a neutral state. We observe an unusual constancy of the resonance Raman spectra over the broad range from pH 9 to 2 and discuss its implications. These results are in accord with recent visible absorption and current measurements of CaChR1 [Sineshchekov, O. A., et al. (2013) Intramolecular proton transfer in channelrhodopsins. Biophys. J. 104, 807–817; Li, H., et al. (2014) Role of a helix B lysine residue in the photoactive site in channelrhodopsins. Biophys. J. 106, 1607–1617]. PMID:24869998

  9. Two fluorescent Schiff base sensors for Zn(2+): the Zn(2+)/Cu(2+) ion interference.

    PubMed

    Jiménez-Sánchez, Arturo; Ortíz, Benjamín; Ortiz Navarrete, Vianney; Farfán, Norberto; Santillan, Rosa

    2015-09-01

    Two simple and low cost 2,4-di-tert-butyl-6-[(1-hydroxycyclohexylmethylimino)methyl]phenol (L1) and 2-[{(1-hydroxycyclohexyl)methylimino}methyl]phenol (L2) Schiff base sensors exhibiting selectivity for Zn(2+) in water:methanol (95:5, v/v, 10 mM HEPES) are described. L1 and L2 display an "off-on" fluorescence effect forming the L1·Zn and L2·Zn complexes, respectively. In the case of L1·Zn, the emission response is quenched by the addition of Cu(2+) forming the respective L1·Cu complex; in spite of that, the fluorescence signal can be completely restored only by the addition of tartrate anions (C4H4O6(2-)) forming again L1·Znvia the "off-on" displacement approach. However, in the case of L2·Zn no Cu(2+) interference is observed, which is a typical problem for Zn(2+) sensors. Here we describe that a very subtle structural change in the ligand during transition from the enol-imine tautomer in L1 to the keto-enamine tautomer in L2 is enough to modulate the Zn(2+)/Cu(2+) selectivity. Also, the Zn(2+)vs. Cd(2+) discrimination for L1 and L2 is proved. Moreover, we found that the interaction between both L·Zn complexes and tartrate anions completely restored the free ligands by the ligand substitution mechanism even in a more efficient association than phosphate anions. Further, a second colorimetric response channel upon addition of Fe(2+) was observed for L1 and L2. Then, TD-DFT theoretical calculations were conducted in order to study the efficiency of the sensors to give different responses in the presence of such metal ions. Finally, the L2 sensor successfully detects Zn(2+) in Jurkat cells cultured with and without Zn(2+) enriched medium. PMID:26192046

  10. Spectral characterization, electrochemical and anticancer studies on some metal(II) complexes containing tridentate quinoxaline Schiff base

    NASA Astrophysics Data System (ADS)

    Chellaian, Justin Dhanaraj; Johnson, Jijo

    2014-06-01

    Co(II), Ni(II), Cu(II) and Zn(II) complexes of a tridentate ONO donor Schiff base ligand derived from 3-(2-aminoethylamino)quinoxalin-2(1H)-one were synthesized. The ligand and its metal complexes were characterized using elemental analysis, molar conductance, IR, 1H NMR, mass, magnetic susceptibility, electronic spectra and ESR spectral studies. Electrochemical behavior of the synthesized compounds was studied using cyclic voltammetry. The grain size of the synthesized compounds was determined by powder XRD. The Schiff base and its complexes have been screened for their antimicrobial activities against the bacterial species E. coli, K. pneumoniae, P. aeruginosa and S. aureus; fungal species include, A. niger, and C. albicans by disc diffusion method. The results show that the complexes have higher activity than the free ligand. The interaction of the complexes with calf thymus DNA (CT DNA) has been investigated by electronic absorption method. Furthermore, the DNA cleavage activity of the complexes was studied using agarose gel electrophoresis. In vitro anticancer studies of the ligand and its complexes using MTT assay was also done.

  11. Experimental and theoretical investigation of a novel mononuclear copper(II) azido compound with tridentate (NNO) Schiff base

    NASA Astrophysics Data System (ADS)

    Karahan, Ahmet; Karabulut, Sedat; Dal, Hakan; Kurtaran, Raif; Leszczynski, Jerzy

    2015-08-01

    The tridentate (NNO) Schiff base (HL), has been prepared by the condensation of 2-(aminomethyl)pyridine with 5-chloro-salicylaldehyde. The mononuclear [N-(2-pyridylmethyl)-3-chloro-salicylaldiminato] (azido) copper(II) complex of general formula [Cu(L)(N3)] (1) has been synthesized by the treatment of HL and CuCl2·2H2O with sodium azide. The ligand and complex have been investigated by various methods including IR, TG-DTA and X-ray diffraction techniques. The complex crystallizes in monoclinic space group P21/c, with unit cell dimensions a = 6.7369(4), b = 11.6058(8), c = 17.1379(11) Å, β = 93.823(2)°. The distorted square-planar Cu(II) ion in complex is chelated by one imino N, one phenolic O and one pyridine N atoms of Schiff base ligand and one N atom of azide ion. The electrochemical behavior of the mononuclear copper azido complex was studied with cyclic voltammetry. Tautomer stability of the ligand and the complex has been determined by molecular modeling techniques. It has been concluded that the HL is more stable than its tautomeric form (THL) both as ligand and complex structures.

  12. Efficient red electroluminescent devices with sterically hindered phosphorescent platinum(II) Schiff base complexes and iridium complex codopant.

    PubMed

    Zhou, Liang; Kwong, Chun-Lam; Kwok, Chi-Chung; Cheng, Gang; Zhang, Hongjie; Che, Chi-Ming

    2014-10-01

    Sterically hindered platinum(II) Schiff base complexes were prepared. Complex 4, which displays red emission with a quantum yield of 0.29 in a thin film and a self-quenching rate constant of 110(-7) dm(3) mol(-1) ?s(-1), was used to fabricate organic light-emitting diodes with single or double emissive layers (EMLs). An iridium(III) complex with a wide band gap was codoped into the electron-dominant EML to act as a deep electron trapper, and red-light-emitting devices with the highest current, power, and external quantum efficiencies of 20.43?cd?A(-1) 18.33?Lm?W(-1), and 11.7%, respectively, were fabricated. A high current efficiency and EQE of up to 14.69?cd?A(-1) and 8.3%, respectively, were achieved at a high brightness of 1000?cd?m(-2). The significant delay of efficiency roll-off is attributed to the bulky 3D structure of the norbornene moiety at the periphery of the Schiff base ligand of 4 and to the new device design strategy. The fabricated device had a projected lifetime (LT50) of 18,000?h. PMID:25145872

  13. Synthesis and evaluation of antitumor activities of novel chiral 1,2,4-triazole Schiff bases bearing ?-butenolide moiety

    PubMed Central

    2012-01-01

    Background 1,2,4-Triazole derivatives have received much attention due to their versatile biological properties including antibacterial, antifungal, anticonvulsant, antiinflammatory, anticancer, and antiproliferative properties. 1,2,4-Triazole nucleus has been incorporated into a wide variety of therapeutically interesting molecules to transform them into better drugs. Schiff bases of 1,2,4-triazoles have also been found to possess extensive biological activities. On the other hand, ?-substituted butenolide moiety represents a biological important entity that is present in numerous biologically active natural products. Results We have described herein the synthesis of 12 hybrid 1,2,4-triazole Schiff bases bearing ?-substituted butenolide moiety. These compounds were synthesized by utilizing the tandem asymmetric Michael addition/elimination reaction as the key step. All the new compounds were evaluated for their in vitro anticancer activity. Conclusions Tandem asymmetric Michael addition/elimination approach has offered an easy access to new chiral 1,2,4-triazole compounds 7a-7l. All these chiral 1,2,4-triazole derivatives exhibited good anticancer activities towards Hela. Of all the tested compounds, the chiral compound 7l with an IC50 of 1.8 ?M was found to be the most active. PMID:22759342

  14. Biologically active and thermally stable polymeric Schiff base and its metal polychelates: Their synthesis and spectral aspects

    NASA Astrophysics Data System (ADS)

    Rasool, Raza; Hasnain, Sumaiya

    2015-09-01

    New metal polychelates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) obtained by the interaction of metal acetates with polymeric Schiff base containing formaldehyde and piperazine, have been investigated. Structural and spectroscopic properties have been evaluated by elemental analysis, FT-IR and 1H-NMR. Geometry of the chelated polymers was confirmed by magnetic susceptibility measurements, UV-Visible spectroscopy and Electron Spin Resonance. The molecular weight of the polymer was determined by gel permeation chromatography (GPC). Thermogravimetric analysis indicated that metal polychelates were more thermally stable than their corresponding ligand. All compounds were screened for their antimicrobial activities against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, (bacteria) and Candida albicans, Microsporum canis, Cryptococcus neoformans (fungi) by agar well diffusion method. Interestingly, the polymeric Schiff base was found to be antimicrobial in nature but less effective as compared to the metal polychelates. On the basis of thermal and antimicrobial behavior, these polymers hold potential applications as thermally resistant antimicrobial and antifouling coating materials as well as antimicrobial packaging materials.

  15. Biologically active and thermally stable polymeric Schiff base and its metal polychelates: Their synthesis and spectral aspects.

    PubMed

    Rasool, Raza; Hasnain, Sumaiya

    2015-09-01

    New metal polychelates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) obtained by the interaction of metal acetates with polymeric Schiff base containing formaldehyde and piperazine, have been investigated. Structural and spectroscopic properties have been evaluated by elemental analysis, FT-IR and (1)H-NMR. Geometry of the chelated polymers was confirmed by magnetic susceptibility measurements, UV-Visible spectroscopy and Electron Spin Resonance. The molecular weight of the polymer was determined by gel permeation chromatography (GPC). Thermogravimetric analysis indicated that metal polychelates were more thermally stable than their corresponding ligand. All compounds were screened for their antimicrobial activities against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, (bacteria) and Candida albicans, Microsporum canis, Cryptococcus neoformans (fungi) by agar well diffusion method. Interestingly, the polymeric Schiff base was found to be antimicrobial in nature but less effective as compared to the metal polychelates. On the basis of thermal and antimicrobial behavior, these polymers hold potential applications as thermally resistant antimicrobial and antifouling coating materials as well as antimicrobial packaging materials. PMID:25955762

  16. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: Spectral, thermal, XRD and antimicrobial studies

    NASA Astrophysics Data System (ADS)

    Sundararajan, M. L.; Jeyakumar, T.; Anandakumaran, J.; Karpanai Selvan, B.

    2014-10-01

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, 1H NMR, 13C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, 1H NMR, 13C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base.

  17. Amidino-containing Schiff base copper(II) and iron(III) chelates as a thrombin inhibitor.

    PubMed

    Toyota, Eiko; Sekizaki, Haruo; Takahashi, Yu-u; Itoh, Kunihiko; Tanizawa, Kazutaka

    2005-01-01

    Four series of Schiff base copper(II) and iron(III) chelates were synthesized from 4-formyl-3-hydroxybenzamidine or 3-formyl-4-hydroxybenzamidine and various L- or D-amino acids. Their inhibitory activities for bovine alpha-thrombin (abbreviated as thrombin) were determined. The most potent thrombin inhibitor in this series is copper(II) chelate (1g') derived from 4-formyl-3-hydroxybenzamidine and D-Trp. Its Ki value, 2.7x10(-8) M, is comparable to that of Argatroban (MD-805), which is a clinically used compound. The iron(III) chelates derived from 4-formyl-3-hydroxybenzamidine and hydrophobic L-amino acids (Val, Ile, Leu, Phe, Trp, Met) also exhibited higher inhibitory potency. It appears that coordination geometry composed of metal ion, amidino group, amino acid side chain is well accommodated to the thrombin active site. From the Ki values of Schiff base metal chelates for thrombin, the structure-activity relationships between the chelates and active site of thrombin were discussed. PMID:15635223

  18. Synthesis, crystal structure and theoretical studies of a Schiff base 2-[4-hydroxy benzylidene]-amino naphthalene.

    PubMed

    Arunagiri, C; Subashini, A; Saranya, M; Thomas Muthiah, P; Thanigaimani, K; Abdul Razak, I

    2015-01-25

    The molecular structure of a new Schiff base, 2-[4-hydroxy benzylidene]-amino naphthalene (HBAN) has been examined by HF and B3LYP/6-311++G(d,p) calculations. The X-ray structure was determined in order to establish the conformation of the molecule. The compound, C17H13NO, crystallizes in the orthorhombic, P212121 space group with the cell dimension, a=6.2867(2), b=10.2108(3), c=19.2950(6) , ?=?=?=90 and z=4. The asymmetric unit contains a molecule of a Schiff base. A strong intermolecular O-H?N and a weak C-H?O hydrogen bonds stabilized the crystal structure. The vibrational spectra of HBAN have been calculated using density functional theoretical computation and compared with the experimental. The study is extended to the HOMO-LUMO analysis to calculate the energy gap (?), Ionization potential (I), Electron Affinity (A), Global Hardness (?), Chemical Potential (?) and Global Electrophilicity (w). The calculated HOMO and LUMO energy reveals that the charge transfer occurs within the molecule. PMID:25084236

  19. Modern spectroscopic technique in the characterization of biosensitive macrocyclic Schiff base ligand and its complexes: Inhibitory activity against plantpathogenic fungi

    NASA Astrophysics Data System (ADS)

    Tyagi, Monika; Chandra, Sulekh; Akhtar, Jameel; Chand, Dinesh

    2014-01-01

    Complexes of the type [M(L)Cl2], where M = Co(II), Ni(II) and Cu(II) have been synthesized with a macrocyclic Schiff base ligand (1,4,5,7,10,11,12,15-octaaza,5,11,16,18-tetraphenyl, 3,4,12,13-tetramethyl cyclo-octadecane) derived from Schiff base (obtained by the condensation of 4-aminoantipyrine and dibenzoyl methane) and ethylenediamine. The ligand was characterized on the basis of elemental analysis, IR, 1H NMR, EI Mass and molecular modeling studies while the complexes were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, IR, electronic and EPR spectral studies. All the complexes are non-electrolyte in nature. The covalency factor (?) and coefficient factor (?) suggest the covalent nature of the complexes. The ligand and its metal complexes have shown antifungal activity with their LD50 values determined by probit analysis against two economically important fungal plant pathogens i.e. Macrophomina phaseolina and Fusarium solani.

  20. Preparation and Characterization of Di-, Tri-, and Tetranuclear Schiff Base Complexes Derived from Diamines and 3,4-Dihydroxybenzaldehyde

    PubMed Central

    Abdulghani, Ahlam Jameel; Khaleel, Asmaa Mohammed Noori

    2013-01-01

    A series of new di-, tri-, and tetranuclear Co(II) and Cu(II) complexes of three new diSchiff base ligands were synthesized by two different methods. The first method involved the synthesis of the three ligands from condensation reaction of 3,4-dihydroxybenzaldehyde (L?H2) with ethylenediamine (en), o-phenylenediamine (o-PD), or 4,5-dimethyl-1,2-phenylendiamine (DMPD) in a mole ratio of 2?:?1 followed by the reaction of the resulting Schiff bases ligands with Cu(II) or Co(II) ions in the presence of 2,2?-bipyridyl (L) to form the di- and trinuclear metal complexes. The second method involved the condensation of the copper complex LCu(II)L? (L = 2,2?-bipyridyl, L? = 4-formylbenzene-1,2-bis(olate)) with en, o-PD, or DMPD in a mole ratio of 2?:?1, respectively, followed by reaction with CuCl2 or Cu(ClO4)2 to form di-, tri-, and tetranuclear copper (II) complexes, respectively. The structures of the ligands and metal complexes were characterized by elemental analyses, NMR, and FTIR spectra. The geometries of metal complexes were suggested according to elemental analysis, electronic spectra, thermal analyses, atomic absorption, and magnetic moments and conductivity measurements. PMID:24453995

  1. Synthesis, physicochemical studies, embryos toxicity and DNA interaction of some new Iron(II) Schiff base amino acid complexes

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, Laila H.; El-Khatib, Rafat M.; Nassr, Lobna A. E.; Abu-Dief, Ahmed M.

    2013-05-01

    New Fe(II) Schiff base amino acid complexes derived from the condensation of o-hydroxynaphthaldehyde with L-alanine, L-phenylalanine, L-aspartic acid, L-histidine and L-arginine were synthesized and characterized by elemental analysis, IR, electronic spectra, and conductance measurements. The stoichiometry and the stability constants of the complexes were determined spectrophotometrically. The investigated Schiff bases exhibited tridentate coordination mode with the general formulae [Fe(HL)2]nH2O for all amino acids except L-histidine. But in case of L-histidine, the ligand acts as tetradentate ([FeL(H2O)2]2H2O), where HL = mono anion and L = dianion of the ligand. The structure of the prepared complexes is suggested to be octahedral. The prepared complexes were tested for their toxicity on chick embryos and found to be safe until a concentration of 100 ?g/egg with full embryos formation. The interaction between CT-DNA and the investigated complexes were followed by spectrophotometry and viscosity measurements. It was found that, the prepared complexes bind to DNA via classical intercalative mode and showed a different DNA cleavage activity with the sequence: nhi > nari > nali > nasi > nphali. The thermodynamic Profile of the binding of nphali complex and CT-DNA was constructed by analyzing the experimental data of absorption titration and UV melting studies with the McGhee equation, van't Hoff's equation, and the Gibbs-Helmholtz equation.

  2. Synthesis of metal complexes involving Schiff base ligand with methylenedioxy moiety: spectral, thermal, XRD and antimicrobial studies.

    PubMed

    Sundararajan, M L; Jeyakumar, T; Anandakumaran, J; Karpanai Selvan, B

    2014-10-15

    Metal complexes of Zn(II), Cd(II), Ni(II), Cu(II), Fe(III), Co(II), Mn(II) Hg(II), and Ag(I) have been synthesized from Schiff base ligand, prepared by the condensation of 3,4-(methylenedioxy)aniline and 5-bromo salicylaldehyde. All the compounds have been characterized by using elemental analysis, molar conductance, FT-IR, UV-Vis, (1)H NMR, (13)C NMR, mass spectra, powder XRD and thermal analysis (TG/DTA) technique. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). The FT-IR, (1)H NMR, (13)C NMR and UV-Vis spectral data suggest that the ligand coordinate to the metal atom by imino nitrogen and phenolic oxygen as bidentate manner. Mass spectral data further support the molecular mass of the compounds and their structure. Powder XRD indicates the crystalline state and morphology of the ligand and its metal complexes. The thermal behaviors of the complexes prove the presence of lattice as well as coordinated water molecules in the complexes. Melting point supports the thermal stability of all the compounds. The in vitro antimicrobial effects of the synthesized compounds were tested against five bacterial and three fungal species by well diffusion method. Antioxidant activities have also been performed for all the compounds. Metal complexes show more biological activity than the Schiff base. PMID:24820326

  3. Synthesis, structures and urease inhibition studies of Schiff base metal complexes derived from 3,5-dibromosalicylaldehyde.

    PubMed

    Cui, Yongming; Dong, Xiongwei; Li, Yuguang; Li, Zuowen; Chen, Wu

    2012-12-01

    Eleven mononuclear copper(II), nickel(II), zinc(II) and cobalt(II) complexes of Schiff base ligands derived from 3,5-dibromosalicylaldehyde/3,5-dichlorosalicylaldehyde were synthesized and determined by single crystal X-ray analysis. The crystal structures of complexes 1, 2, 4, 5, 6, 8 and 11 present the square-planar coordination geometry at the metal center and complexes 7, 9 and 10 show the distorted tetrahedral geometry. While one copper center in 3 has a square-planar geometry, the other copper is slightly distorted square-planar. The inhibitory activities of all the obtained complexes were tested in vitro against jack bean urease. It was found that Schiff base copper(II) complexes 1, 3, 5, 8 and 11 showed strong urease inhibitory activities (IC(50) = 1.51-3.52 ?M) compared with acetohydroxamic acid (IC(50) = 62.52 ?M), which was a positive reference. Their structure-activity relationships were further discussed. PMID:23142672

  4. Co(II) and Cd(II) complexes derived from heterocyclic Schiff-Bases: synthesis, structural characterisation, and biological activity.

    PubMed

    Ahmed, Riyadh M; Yousif, Enaam I; Al-Jeboori, Mohamad J

    2013-01-01

    New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N'-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L) and N'-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L) are reported. Schiff-base ligands L and L were derived from condensation of 3-hydroxy-4-methoxybenzaldehyde (iso-vanillin) with furan-2-carboxylic acid hydrazide and thiophene-2-carboxylic acid hydrazide, respectively. Complexes of the general formula [M(L)?]Cl? (where M = Co(II) or Cd(II), L?=?L or L) have been obtained from the reaction of the corresponding metal chloride with the ligands. The ligands and their metal complexes were characterised by spectroscopic methods (FTIR, UV-Vis, H, and C NMR spectra), elemental analysis, metal content, magnetic measurement, and conductance. These studies revealed the formation of four-coordinate complexes in which the geometry about metal ion is tetrahedral. Biological activity of the ligands and their metal complexes against gram positive bacterial strain Bacillus (G+) and gram negative bacteria Pseudomonas (G-) revealed that the metal complexes become less resistive to the microbial activities as compared to the free ligands. PMID:24027449

  5. pH-metric and spectroscopic properties of new 4-hydroxysalicylidene-2-aminopyrimidine Schiff-base transition metal complexes

    NASA Astrophysics Data System (ADS)

    Ouf, Abd El-Fatah; Ali, Mayada S.; Saad, Eman M.; Mostafa, Sahar I.

    2010-06-01

    The new complexes, cis-[WO 2(Hsap) 2], [Ru(PPh 3) 2(Hsap) 2], [Pd(Hsap)Cl(H 2O)], [Pd(PPh 3) 2(Hsap)]Cl, [Ag(Hsap)(H 2O) 2], [Ni(Hsap)(AcO)(H 2O) 2], [Ni(Hsap) 2] and [Cu(Hsap)Cl(H 2O)] are reported, where H 2sap is 4-hydroxysalicylidene-2-amino pyrimidine Schiff-base. The complexes were characterized by elemental analyses, spectroscopic (IR, NMR, UV-vis, ESR and mass) and physical techniques (conductivity, magnetic and thermal measurements). The Schiff-base H 2sap behaves as a bidentate chelate with the deprotonated 2-hydroxy and azomethine nitrogen centers with the pendant pyrimidine cyclic nitrogen functionality playing no role in coordination. The dissociation constants of H 2sap and the stability constants of the metal complexes have been determined pH-metrically at various temperatures, and the thermodynamic activation parameters (? S*, ? G*, ? H*) calculated.

  6. A Chromone-Derived Schiff-Base Ligand as Al(3+) "Turn on" Fluorescent Sensor: Synthesis and Spectroscopic Properties.

    PubMed

    Li, Chao-Rui; Qin, Jing-Can; Wang, Bao-Dui; Fan, Long; Yan, Jun; Yang, Zheng-Yin

    2016-01-01

    In this study, a novel chromone-derived Schiff-base ligand called 6-Hydroxy-3-formylchromone (2'-furan formyl) hydrazone (HCFH) has been designed and synthesized as a "turn on" fluorescent sensor for Al(3+). This sensor HCFH showed high selectivity and sensitivity towards Al(3+) over other metal ions investigated, and most metal ions had nearly no influences on the fluorescence response of HCFH to Al(3+). Additionally, the significant enhancement by about 171-fold in fluorescence emission intensity at 502nm was observed in the presence of Al(3+) in ethanol, and it was due to the chelation-enhanced fluorescence (CHEF) effect upon complexation of HCFH with Al(3+) which inhibited the photoinduced electron transfer (PET) phenomenon from the Schiff-base nitrogen atom to chromone group. Moreover, this sensor formed a 1 : 1 complex with Al(3+) and the fluorescence response of HCFH to Al(3+) was nearly completed within 1min. Thus, this sensor HCFH could be used to detect and recognize Al(3+) for real-time detection. Graphical Abstract Chromone derivate HCFH for selective detection of Al(3+) with fluorescence enhancement. PMID:26545355

  7. Synthesis, spectral characterization, molecular modeling and antimicrobial studies of tridentate azo-dye Schiff base metal complexes

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Zayed, Mohamed E.; Alharbi, Suliman A.

    2015-03-01

    Nine mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pt(IV) complexes of azo-dye Schiff's base ligand were synthesized and determined by different physical techniques. All the nine metal complexes are reported using elemental analysis, molar conductance, magnetic susceptibility, IR, UV-Vis, thermal analysis and 1H NMR, 13C NMR, mass, SEM, TEM, EDX, XRD spectral studies. The molar conductance measurements of all the complexes in DMF solution correspond to non-electrolytic nature. All complexes were of the high-spin type and found to have six-coordinate octahedral geometry except the Cu(II) complex which was four coordinate, square planar. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. In molecular modeling the geometries of azo-dye Schiff base ligand HL and its metal (II/III/IV) complexes were fully optimized with respect to the energy using the 6-31G basis set. These ligand and its metal complexes have also been screened for their in vitro antimicrobial activities.

  8. Modern spectroscopic technique in the characterization of biosensitive macrocyclic Schiff base ligand and its complexes: inhibitory activity against plantpathogenic fungi.

    PubMed

    Tyagi, Monika; Chandra, Sulekh; Akhtar, Jameel; Chand, Dinesh

    2014-01-24

    Complexes of the type [M(L)Cl2], where M = Co(II), Ni(II) and Cu(II) have been synthesized with a macrocyclic Schiff base ligand (1,4,5,7,10,11,12,15-octaaza,5,11,16,18-tetraphenyl, 3,4,12,13-tetramethyl cyclo-octadecane) derived from Schiff base (obtained by the condensation of 4-aminoantipyrine and dibenzoyl methane) and ethylenediamine. The ligand was characterized on the basis of elemental analysis, IR, (1)H NMR, EI Mass and molecular modeling studies while the complexes were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, IR, electronic and EPR spectral studies. All the complexes are non-electrolyte in nature. The covalency factor (?) and coefficient factor (?) suggest the covalent nature of the complexes. The ligand and its metal complexes have shown antifungal activity with their LD50 values determined by probit analysis against two economically important fungal plant pathogens i.e. Macrophomina phaseolina and Fusarium solani. PMID:24161868

  9. A highly sensitive and selective fluorescent chemosensor for detection of Zn2+ based on a Schiff base

    NASA Astrophysics Data System (ADS)

    Roy, Nayan; Pramanik, Harun A. R.; Paul, Pradip C.; Singh, T. Sanjoy

    2015-04-01

    A Schiff-base fluorescent probe - 2-((E)-(quinolin-8-ylimino)methyl)quinolin-8-ol (H7L) was synthesized and evaluated as a chemoselective Zn2+ sensor. Upon treatment with Zn2+, the complexation of H7L with Zn2+ resulted in a red shift with a pronounced enhancement in the fluorescence emission intensity in ethanol solution. Moreover, other common alkali, alkaline earth and transition metal ions failed to induce response or minimal spectral changes. Notably, this chemosensor could distinguish clearly Zn2+ from Cd2+. Fluorescence studies on H7L and H7L-Zn2+ complex reveal that the quantum yield strongly increases upon coordination. The stoichiometric ratio and association constant were evaluated using Benesi-Hildebrand relation giving 1:1 stoichiometry. This further corroborated 1:1 complex formation based on Job's plot analyses. This chemosensor exhibits a very good fluorescence sensing ability to Zn2+ over a wide range of pH.

  10. Coordination behavior of new bis Schiff base ligand derived from 2-furan carboxaldehyde and propane-1,3-diamine. Spectroscopic, thermal, anticancer and antibacterial activity studies

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; Zayed, Ehab M.; Hindy, Ahmed M. M.

    2015-06-01

    Novel bis Schiff base ligand, [N1,N3-bis(furan-2-ylmethylene)propane-1,3-diamine], was prepared by the condensation of furan-2-carboxaldehyde with propane-1,3-diamine. Its conformational changes on complexation with transition metal ions [Co(II), Ni(II), Cu(II), Mn(II), Cd(II), Zn(II) and Fe(III)] have been studied on the basis of elemental analysis, conductivity measurements, spectral (infrared, 1H NMR, electronic), magnetic and thermogravimetric studies. The conductance data of the complexes revealed their electrolytic nature suggesting them as 1:2 (for bivalent metal ions) and 1:3 (for Fe(III) ion) electrolytes. The complexes were found to have octahedral geometry based on magnetic moment and solid reflectance measurements. Thermal analysis data revealed the decomposition of the complexes in successive steps with the removal of anions, coordinated water and bis Schiff base ligand. The thermodynamic parameters were calculated using Coats-Redfern equation. The Anticancer screening studies were performed on human colorectal cancer (HCT), hepatic cancer (HepG2) and breast cancer (MCF-7) cell lines. The antimicrobial activity of all the compounds was studied against Gram negative (Escherichia coli and Proteus vulgaris) and Gram positive (Bacillus vulgaris and Staphylococcus pyogones) bacteria. It was observed that the coordination of metal ion has a pronounced effect on the microbial activities of the bis Schiff base ligand. All the metal complexes have shown higher antimicrobial effect than the free bis Schiff base ligand.

  11. Antimicrobial efficacy of phenanthrenequinone based Schiff base complexes incorporating methionine amino acid: Structural elucidation and in vitro bio assay

    NASA Astrophysics Data System (ADS)

    Arun, Thesingu Rajan; Raman, Natarajan

    2014-06-01

    This work focuses the synthesis and characterization of few novel mixed ligand Schiff base metal complexes and their biological activities. For deriving the structural aspects, spectral techniques such as FT-IR, UV-Vis., 1H NMR, Raman, EPR and the physicochemical characterizations including elemental analysis, molar conductance and magnetic susceptibility method have been involved. All the complexes adopt square planar geometry. DNA binding ability of these complexes has been explored using diverse techniques viz. UV-Vis. absorption, fluorescence spectroscopy, viscometry and cyclic voltammetry. These studies prove that CT-DNA binding of the complexes follows the intercalation mode. Comparative DNA oxidative cleavage ability of the complexes has been done under ultraviolet photo radiation on pUC19 DNA. In addition, the biocidal action of the complexes has been investigated against few pathogenic bacteria and fungi by disc diffusion method. Importantly, the amylase inhibition activity of Cu(II) complex has been explored. The amylase inhibition property has been found to be increased upon increasing the complex concentration.

  12. Nickel analysis in real samples by Ni2+ selective PVC membrane electrode based on a new Schiff base.

    PubMed

    Tomar, Praveen Kumar; Chandra, Sulekh; Malik, Amrita; Kumar, Ankit

    2013-12-01

    A newly synthesized Schiff base 3-aminoacetophenonesemicarbazone (AAS) has been used for the preparation of Ni(2+) selective PVC membrane electrode. The proposed electrode exhibits a Nernstian response over the nickel concentration range of 1.010(-7) to 1.010(-2)mol L(-1) with a slope of 30.00.3 mV/decade of concentration. The limit of detection as determined from the intersection linear segment of the calibration plot is 5.110(-8) mol L(-1). The electrode shows good selectivity towards nickel with respect to several alkali, alkaline earth, transition and heavy metal ions. The response time of the electrode is very fast (?10 s) and can be used for 17 weeks in the pH range of 2.0-9.8. The electrode can also be used in partially non-aqueous media having up to 20% (v/v) methanol, ethanol or acetone content with no significant change in the value of slope or working concentration range. To investigate the analytical applicability of the electrode, it was successfully applied as an indicator electrode in Ni(2+) ion potentiometric titration with EDTA, and in direct determination of nickel(II) in real samples. PMID:24094213

  13. Metal based photosensitizers of tetradentate Schiff base: promising role in anti-tumor activity through singlet oxygen generation mechanism.

    PubMed

    Pradeepa, S M; Bhojya Naik, H S; Vinay Kumar, B; Indira Priyadarsini, K; Barik, Atanu; Ravikumar Naik, T R; Prabhakara, M C

    2013-11-01

    In the present investigation, a Schiff base N'(1),N'(3)-bis[(Z)-(2-hydroxynapthyl)methylidene]benzene-1,3-dicarbodihydrazide (L1) and its Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized as novel photosensitizing agents for photodynamic therapy (PDT). The interaction of these complexes with calf thymus DNA (CT DNA) has been explored using absorption, thermal denaturation and viscometric studies. The experimental results revealed that Co(II) and Ni(II) complexes on binding to CT DNA imply a covalent mode, most possibly involving guanine N7 nitrogen of DNA, with an intrinsic binding constant Kb of 4.510(4)M(-1) and 4.210(4)M(-1), respectively. However, interestingly, the Cu(II) complex is involved in the surface binding to minor groove via phosphate backbone of DNA double helix with an intrinsic binding constant Kb of 5.710(4)M(-1). The Co(II), Ni(II) and Cu(II) complexes are active in cleaving supercoiled (SC) pUC19 DNA on photoexposure to UV-visible light of 365nm, through (1)O2 generation with quantum yields of 0.28, 0.25 and 0.30, respectively. Further, these complexes are cytotoxic in A549 lung cancer cells, showing an enhancement of cytotoxicity upon light irradiation. PMID:23831972

  14. Evidence that MutY is a monofunctional glycosylase capable of forming a covalent Schiff base intermediate with substrate DNA.

    PubMed

    Williams, S D; David, S S

    1998-11-15

    The Escherichia coli adenine glycosylase MutY is involved in the repair of 7,8-dihydro-8-oxo-2'-deoxyguanosine (OG):A and G:A mispairs in DNA. DNA strand cleavage via beta-elimination (beta-lyase) activity coupled with MutY's removal of misincorporated adenine bases was sought using both qualitative and quantitative methods. The qualitative assays demonstrate formation of a Schiff base intermediate which is characteristic of DNA glycosylases catalyzing a concomitant beta-lyase reaction. Borohydride reduction of the Schiff base results in the formation of a covalent DNA-MutY adduct which is easily detected in SDS-PAGE experiments. However, quantitative activity assays which monitor DNA strand scission accompanying base release suggest MutY behaves as a simple monofunctional glycosylase. Treatment with base effects DNA strand cleavage at apurinic/apyrimidinic (AP) sites arising via simple glycosylase activity. The amount of cleaved DNA in MutY reactions treated with base is much greater than that in non-base treated reactions, indicating that AP site generation by MutY is not associated with a concomitant beta-lyase step. As standards, identical assays were performed with a known monofunctional enzyme (uracil DNA glycosylase) and a known bifunctional glycosylase/lyase (FPG), the results of which were used in comparison with those of the MutY experiments. The apparent inconsistency between the data obtained for MutY by the qualitative and quantitative methods underscores the current debate surrounding the catalytic activity of this enzyme, and a detailed explanation of this controversy is proposed. The work presented here lays ground for the identification of specific active site residues responsible for the chemical mechanism of MutY enzyme catalysis. PMID:9801309

  15. Synthesis, spectroscopic, cytotoxic aspects and computational study of N-(pyridine-2-ylmethylene)benzo[d]thiazol-2-amine Schiff base and some of its transition metal complexes

    NASA Astrophysics Data System (ADS)

    Abd El-Aziz, Dina M.; Etaiw, Safaa Eldin H.; Ali, Elham A.

    2013-09-01

    N-(pyridine-2-ylmethylene)benzo[d]thiazol-2-amine Schiff base (L) and its Cu(II), Fe(III), Co(II), Ni(II) and Zn(II) complexes were synthesized and characterized by a set of chemical and spectroscopic measurements using elemental analysis, electrical conductance, mass spectra, magnetic susceptibility and spectral techniques (IR, UV-Vis, 1H NMR). Elemental and mass spectrometric data are consistent with the proposed formula. IR spectra confirm the bidentate nature of the Schiff base ligand. The octahedral geometry around Cu(II), Fe(III), Ni(II) and Zn(II) as well as tetrahedral geometry around Co(II) were suggested by UV-Vis spectra and magnetic moment data. The thermal degradation behavior of the Schiff base and its complexes was investigated by thermogravimetric analysis. The structure of the Schiff base and its transition metal complexes was also theoretically studied using molecular mechanics (MM+). The obtained structures were minimized with a semi-empirical (PM3) method. The in vitro antitumor activity of the synthesized compounds was studied. The Zn-complex exhibits significant decrease in surviving fraction of breast carcinoma (MCF 7), liver carcinoma (HEPG2), colon carcinoma (HCT116) and larynx carcinoma (HEP2) cell lines human cancer.

  16. BaFe12O19-chitosan Schiff-base Ag (I) complexes embedded in carbon nanotube networks for high-performance electromagnetic materials

    PubMed Central

    Zhao, Jie; Xie, Yu; Guan, Dongsheng; Hua, Helin; Zhong, Rong; Qin, Yuancheng; Fang, Jing; Liu, Huilong; Chen, Junhong

    2015-01-01

    The multiwalled carbon nanotubes/BaFe12O19-chitosan (MCNTs/BF-CS) Schiff base Ag (I) complex composites were synthesized successfully by a chemical bonding method. The morphology and structures of the composites were characterized with electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. Their conductive properties were measured using a four-probe conductivity tester at room temperature, and their magnetic properties were tested by a vibrating sample magnetometer. The results show that the BF-CS Schiff base Ag (I) complexes are embedded into MCNT networks. When the mass ratio of MCNTs and BF-CS Schiff base is 0.95:1, the conductivity, Ms (saturation magnetization), Mr (residual magnetization), and Hc (coercivity) of the BF-CS Schiff base composites reach 1.908 S cm−1, 28.20 emu g−1, 16.66 emu g−1 and 3604.79 Oe, respectively. Finally, a possible magnetic mechanism of the composites has also been proposed. PMID:26218269

  17. Synthesis, spectral characterization and biological activity of zinc(II) complexes with 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole Schiff bases

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Pandey, O. P.; Sengupta, S. K.

    New Zn(II) complexes have been synthesized by the reactions of zinc(II) acetate with Schiff bases derived from 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde, 2-hydroxyacetophenone or indoline-2,3-dione. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non-electrolytes. Elemental analyses suggest that the complexes have 1:1 stoichiometry of the type [ZnL(H 2O) 2], [ZnL'(OAc) 2(H 2O) 2] (L = dianionic Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and 2-hydroxyacetophenone or indoline-2,3-dione; L' = neutral Schiff bases derived from 3-(substituted phenyl)-4-amino-5-hydrazino-1, 2, 4-triazole and benzaldehyde) and they were characterized by FT-IR, 1H NMR, 13C NMR and FAB mass. All these Schiff bases and their complexes have also been screened for their antibacterial activities against Bacillus subtilis, Escherichia coli and antifungal activities against Colletotrichum falcatum, Aspergillus niger, Fusarium oxysporium and Carvularia pallescence by petriplates methods.

  18. BaFe12O19-chitosan Schiff-base Ag (I) complexes embedded in carbon nanotube networks for high-performance electromagnetic materials

    NASA Astrophysics Data System (ADS)

    Zhao, Jie; Xie, Yu; Guan, Dongsheng; Hua, Helin; Zhong, Rong; Qin, Yuancheng; Fang, Jing; Liu, Huilong; Chen, Junhong

    2015-07-01

    The multiwalled carbon nanotubes/BaFe12O19-chitosan (MCNTs/BF-CS) Schiff base Ag (I) complex composites were synthesized successfully by a chemical bonding method. The morphology and structures of the composites were characterized with electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. Their conductive properties were measured using a four-probe conductivity tester at room temperature, and their magnetic properties were tested by a vibrating sample magnetometer. The results show that the BF-CS Schiff base Ag (I) complexes are embedded into MCNT networks. When the mass ratio of MCNTs and BF-CS Schiff base is 0.95:1, the conductivity, Ms (saturation magnetization), Mr (residual magnetization), and Hc (coercivity) of the BF-CS Schiff base composites reach 1.908?S?cm-1, 28.20?emu?g-1, 16.66?emu?g-1 and 3604.79?Oe, respectively. Finally, a possible magnetic mechanism of the composites has also been proposed.

  19. Synthesis, crystal structure, fluorescence and electrochemical studies of a new tridentate Schiff base ligand and its nickel(II) and palladium(II) complexes

    NASA Astrophysics Data System (ADS)

    Shafaatian, Bita; Soleymanpour, Ahmad; Kholghi Oskouei, Nasim; Notash, Behrouz; Rezvani, Seyyed Ahmad

    2014-07-01

    A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1 M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1 M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s-1 scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, 1H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction.

  20. BaFe12O19-chitosan Schiff-base Ag (I) complexes embedded in carbon nanotube networks for high-performance electromagnetic materials.

    PubMed

    Zhao, Jie; Xie, Yu; Guan, Dongsheng; Hua, Helin; Zhong, Rong; Qin, Yuancheng; Fang, Jing; Liu, Huilong; Chen, Junhong

    2015-01-01

    The multiwalled carbon nanotubes/BaFe12O19-chitosan (MCNTs/BF-CS) Schiff base Ag (I) complex composites were synthesized successfully by a chemical bonding method. The morphology and structures of the composites were characterized with electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction techniques. Their conductive properties were measured using a four-probe conductivity tester at room temperature, and their magnetic properties were tested by a vibrating sample magnetometer. The results show that the BF-CS Schiff base Ag (I) complexes are embedded into MCNT networks. When the mass ratio of MCNTs and BF-CS Schiff base is 0.95:1, the conductivity, Ms (saturation magnetization), Mr (residual magnetization), and Hc (coercivity) of the BF-CS Schiff base composites reach 1.908 S cm(-1), 28.20 emu g(-1), 16.66 emu g(-1) and 3604.79 Oe, respectively. Finally, a possible magnetic mechanism of the composites has also been proposed. PMID:26218269

  1. Origin of Water-Induced Fluorescence Turn-On from a Schiff Base Compound: AIE or H-Bonding Promoted ESIPT?

    PubMed

    McDonald, Lucas; Wang, Junfeng; Alexander, Nick; Li, Hui; Liu, Tianbo; Pang, Yi

    2016-02-01

    A nonfluorescent Schiff base compound (4) in an aprotic solvent (e.g., CH3CN) is found to give blue fluorescence turn-on (?em ? 475 nm) upon addition of H2O. By using a wide range of spectroscopic methods, including (1)H NMR and dynamic light scattering, the fluorescence response is shown to be not originating from the molecular aggregation-induced emission (AIE). Spectroscopic studies at low temperatures further reveal a dynamic response of 4 to temperature, showing that the excited state intramolecular proton transfer (ESIPT) can be ON or OFF through interaction with protic solvent. In the binary solvent (with composition CH3CN/H2O = 3:1), the Schiff base gives ESIPT emission (?em ? 524 nm) only at extremely low temperature (below -80 C), which is turned off when being warmed to -60 C, attributing to the increasing photoinduced electron transfer (PET) effect. When the temperature is further raised to -20 C, ESIPT emission is reactivated to give blue emission (?em ? 475 nm) that is observed at room temperature. The observed dynamic fluorescence response reveals that ESIPT could be a predominant mechanism in the fluorescence turn-on of Schiff base compounds, although both AIE and ESIPT mechanisms could operate. The assumption is further verified by examining the response of Schiff base to Al(3+) cation. PMID:26761400

  2. Synthesis, spectroscopic studies and inhibitory activity against bactria and fungi of acyclic and macrocyclic transition metal complexes containing a triamine coumarine Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Abou-Hussein, A. A.; Linert, Wolfgang

    2015-04-01

    Two series of new mono and binuclear complexes with a Schiff base ligand derived from the condensation of 3-acetylcoumarine and diethylenetriamine, in the molar ratio 2:1 have been prepared. The ligand was characterized by elemental analysis, IR, UV-visible, 1H-NMR and mass spectra. The reaction of the Schiff base ligand with cobalt(II), nickel(II), copper(II), zinc(II) and oxovanadium(IV) lead to mono or binuclear species of cyclic or macrocyclic complexes, depending on the mole ratio of metal to ligand and as well as on the method of preparation. The Schiff base ligand behaves as a cyclic bidentate, tetradendate or pentaentadentae ligand. The formation of macrocyclic complexes depends significantly on the dimension of the internal cavity, the rigidity of the macrocycles, the nature of its donor atoms and on the complexing properties of the anion involved in the coordination. Electronic spectra and magnetic moments of the complexes indicate that the geometries of the metal centers are either square pyramidal or octahedral for acyclic or macro-cyclic complexes. The structures are consistent with the IR, UV-visible, ESR, 1H-NMR, mass spectra as well as conductivity and magnetic moment measurements. The Schiff base ligand and its metal complexes were tested against two pathogenic bacteria as Gram-positive and Gram-negative bacteria as well as one kind of fungi. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

  3. Synthesis, crystal structure, fluorescence and electrochemical studies of a new tridentate Schiff base ligand and its nickel(II) and palladium(II) complexes.

    PubMed

    Shafaatian, Bita; Soleymanpour, Ahmad; Kholghi Oskouei, Nasim; Notash, Behrouz; Rezvani, Seyyed Ahmad

    2014-07-15

    A new unsymmetrical tridentate Schiff base ligand was derived from the 1:1M condensation of ortho-vanillin with 2-mercaptoethylamine. Nickel and palladium complexes were obtained by the reaction of the tridentate Schiff base ligand with nickel(II) acetate tetrahydrate and palladium(II) acetate in 2:1M ratio. In nickel and palladium complexes the ligand was coordinated to metals via the imine N and enolic O atoms. The S groups of Schiff bases were not coordinated to the metals and S-S coupling was occured. The complexes have been found to possess 1:2 Metal:Ligand stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The complexes exhibited octahedral coordination geometry. The emission spectra of the ligand and its complexes were studied in methanol. Electrochemical properties of the ligand and its metal complexes were investigated in the CH3CN solvent at the 100 mV s(-1) scan rate. The ligand and metal complexes showed both reversible and quasi-reversible processes at this scan rate. The Schiff base and its complexes have been characterized by IR, (1)H NMR, UV/Vis, elemental analyses and conductometry. The crystal structure of nickel complex has been determined by single crystal X-ray diffraction. PMID:24681321

  4. Synthesis, spectral, thermal and magnetic studies of Mn(II), Ni(II) and Cu(II) complexes with some benzopyran-4-one Schiff bases

    NASA Astrophysics Data System (ADS)

    El-Ansary, Aida L.; Abdel-Fattah, Hussein M.; Abdel-Kader, Nora S.

    2011-08-01

    The Schiff bases of N 2O 2 dibasic ligands, H 2La and H 2Lb are prepared by the condensation of ethylenediamine (a) and trimethylenediamine (b) with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzopyran-4-one. Also tetra basic ligands, H 4La and H 4Lb are prepared by the condensation of aliphatic amines (a) and (b) with 6-formyl-5,7-dihydroxy-2-methylbenzopyran-4-one. New complexes of H 4La and H 4Lb with metal ions Mn(II), Ni(II) and Cu(II) are synthesized, in addition Mn(II) complexes with ligands H 2La and H 2Lb are also synthesized. Elemental and thermal analyses, infrared, ultraviolet-visible as well as conductivity and magnetic susceptibility measurements are used to elucidate the structure of the newly prepared metal complexes. The structures of copper(II) complexes are also assigned based upon ESR spectra study. All the complexes separated with the stoichiometric ratio (1:1) (M:L) except Mn-H 4La and Mn-H 4Lb with (2:1) (M:L) molar ratio. In metal chelates of the type 1:1 (M:L), the Schiff bases behave as a dinegative N 2O 2 tetradentate ligands. Moreover in 2:1 (M:L) complexes, the Schiff base molecules act as mono negative bidentate ligand and binuclear complex is then formed. The Schiff bases were assayed by the disc diffusion method for antibacterial activity against Staphylococcus aureus and Escherichia coli. The antifungal activity of the Schiff bases was also evaluated against the fungi Aspergillus flavus and Candida albicans.

  5. An efficient method for solution-phase parallel synthesis of 2-quinoxalinol salen Schiff-base ligands.

    PubMed

    Wu, Xianghong; Gorden, Anne E V

    2007-01-01

    A solution-phase parallel method for the synthesis of 2-quinoxalinol salen ligands was designed and optimized. The synthesis begins with commercially available 1,5-difluoro-2, 4-dinitrobenzene (DFDNB) and employs a sequence of five straightforward and high-yielding reaction steps. Simple laboratory techniques with low sensitivity to water or air for solution-phase parallel reactions were coupled with convenient workup and purification procedures to give high-purity and yield a small ligand library of 20 compounds. The final step, a Schiff-base condensation of an aldehyde with the diaminoquinoxaline results in a new category of ligands for metal coordination or of potential bioactivity, based on the skeleton 2,2'-(1E,1'E)-(quinoxaline-6,7-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-1-ylidene)diphenol. The approach described here is easily adaptable for parallel synthesis of a larger library. PMID:17497932

  6. Probing the Carbonyl Functionality of a Petroleum Resin and Asphaltene through Oximation and Schiff Base Formation in Conjunction with N-15 NMR.

    PubMed

    Thorn, Kevin A; Cox, Larry G

    2015-01-01

    Despite recent advances in spectroscopic techniques, there is uncertainty regarding the nature of the carbonyl groups in the asphaltene and resin fractions of crude oil, information necessary for an understanding of the physical properties and environmental fate of these materials. Carbonyl and hydroxyl group functionalities are not observed in natural abundance 13C nuclear magnetic resonance (NMR) spectra of asphaltenes and resins and therefore require spin labeling techniques for detection. In this study, the carbonyl functionalities of the resin and asphaltene fractions from a light aliphatic crude oil that is the source of groundwater contamination at the long term USGS study site near Bemidji, Minnesota, have been examined through reaction with 15N-labeled hydroxylamine and aniline in conjunction with analysis by solid and liquid state 15N NMR. Ketone groups were revealed through 15N NMR detection of their oxime and Schiff base derivatives, and esters through their hydroxamic acid derivatives. Anilinohydroquinone adducts provided evidence for quinones. Some possible configurations of the ketone groups in the resin and asphaltene fractions can be inferred from a consideration of the likely reactions that lead to heterocyclic condensation products with aniline and to the Beckmann reaction products from the initially formed oximes. These include aromatic ketones and ketones adjacent to quaternary carbon centers, β-hydroxyketones, β-diketones, and β-ketoesters. In a solid state cross polarization/magic angle spinning (CP/MAS) 15N NMR spectrum recorded on the underivatized asphaltene as a control, carbazole and pyrrole-like nitrogens were the major naturally abundant nitrogens detected. PMID:26556054

  7. Probing the carbonyl functionality of a petroleum resin and asphaltene through oximation and schiff base formation in conjunction with N-15 NMR

    USGS Publications Warehouse

    Thorn, Kevin A.; Cox, Larry G.

    2015-01-01

    Despite recent advances in spectroscopic techniques, there is uncertainty regarding the nature of the carbonyl groups in the asphaltene and resin fractions of crude oil, information necessary for an understanding of the physical properties and environmental fate of these materials. Carbonyl and hydroxyl group functionalities are not observed in natural abundance 13C nuclear magnetic resonance (NMR) spectra of asphaltenes and resins and therefore require spin labeling techniques for detection. In this study, the carbonyl functionalities of the resin and asphaltene fractions from a light aliphatic crude oil that is the source of groundwater contamination at the long term USGS study site near Bemidji, Minnesota, have been examined through reaction with 15N-labeled hydroxylamine and aniline in conjunction with analysis by solid and liquid state 15N NMR. Ketone groups were revealed through 15N NMR detection of their oxime and Schiff base derivatives, and esters through their hydroxamic acid derivatives. Anilinohydroquinone adducts provided evidence for quinones. Some possible configurations of the ketone groups in the resin and asphaltene fractions can be inferred from a consideration of the likely reactions that lead to heterocyclic condensation products with aniline and to the Beckmann reaction products from the initially formed oximes. These include aromatic ketones and ketones adjacent to quaternary carbon centers, β-hydroxyketones, β-diketones, and β-ketoesters. In a solid state cross polarization/magic angle spinning (CP/MAS) 15N NMR spectrum recorded on the underivatized asphaltene as a control, carbazole and pyrrole-like nitrogens were the major naturally abundant nitrogens detected.

  8. Charge and Spin States in Schiff Base Metal Complexes with a Disiloxane Unit Exhibiting a Strong Noninnocent Ligand Character: Synthesis, Structure, Spectroelectrochemistry, and Theoretical Calculations.

    PubMed

    Cazacu, Maria; Shova, Sergiu; Soroceanu, Alina; Machata, Peter; Bucinsky, Lukas; Breza, Martin; Rapta, Peter; Telser, Joshua; Krzystek, J; Arion, Vladimir B

    2015-06-15

    Mononuclear nickel(II), copper(II), and manganese(III) complexes with a noninnocent tetradentate Schiff base ligand containing a disiloxane unit were prepared in situ by reaction of 3,5-di-tert-butyl-2-hydroxybenzaldehyde with 1,3-bis(3-aminopropyl)tetramethyldisiloxane followed by addition of the appropriate metal(II) salt. The ligand H2L resulting from these reactions is a 2:1 condensation product of 3,5-di-tert-butyl-2-hydroxybenzaldehyde with 1,3-bis(3-aminopropyl)tetramethyldisiloxane. The resulting metal complexes, NiL·0.5CH2Cl2, CuL·1.5H2O, and MnL(OAc)·0.15H2O, were characterized by elemental analysis, spectroscopic methods (IR, UV-vis, X-band EPR, HFEPR, (1)H NMR), ESI mass spectrometry, and single crystal X-ray diffraction. Taking into account the well-known strong stabilizing effects of tert-butyl groups in positions 3 and 5 of the aromatic ring on phenoxyl radicals, we studied the one-electron and two-electron oxidation of the compounds using both experimental (chiefly spectroelectrochemistry) and computational (DFT) techniques. The calculated spin-density distribution and localized orbitals analysis revealed the oxidation locus and the effect of the electrochemical electron transfer on the molecular structure of the complexes, while time-dependent DFT calculations helped to explain the absorption spectra of the electrochemically generated species. Hyperfine coupling constants, g-tensors, and zero-field splitting parameters have been calculated at the DFT level of theory. Finally, the CASSCF approach has been employed to theoretically explore the zero-field splitting of the S = 2 MnL(OAc) complex for comparison purposes with the DFT and experimental HFEPR results. It is found that the D parameter sign strongly depends on the metal coordination geometry. PMID:26030801

  9. Probing the Carbonyl Functionality of a Petroleum Resin and Asphaltene through Oximation and Schiff Base Formation in Conjunction with N-15 NMR

    PubMed Central

    Thorn, Kevin A.; Cox, Larry G.

    2015-01-01

    Despite recent advances in spectroscopic techniques, there is uncertainty regarding the nature of the carbonyl groups in the asphaltene and resin fractions of crude oil, information necessary for an understanding of the physical properties and environmental fate of these materials. Carbonyl and hydroxyl group functionalities are not observed in natural abundance 13C nuclear magnetic resonance (NMR) spectra of asphaltenes and resins and therefore require spin labeling techniques for detection. In this study, the carbonyl functionalities of the resin and asphaltene fractions from a light aliphatic crude oil that is the source of groundwater contamination at the long term USGS study site near Bemidji, Minnesota, have been examined through reaction with 15N-labeled hydroxylamine and aniline in conjunction with analysis by solid and liquid state 15N NMR. Ketone groups were revealed through 15N NMR detection of their oxime and Schiff base derivatives, and esters through their hydroxamic acid derivatives. Anilinohydroquinone adducts provided evidence for quinones. Some possible configurations of the ketone groups in the resin and asphaltene fractions can be inferred from a consideration of the likely reactions that lead to heterocyclic condensation products with aniline and to the Beckmann reaction products from the initially formed oximes. These include aromatic ketones and ketones adjacent to quaternary carbon centers, β-hydroxyketones, β-diketones, and β-ketoesters. In a solid state cross polarization/magic angle spinning (CP/MAS) 15N NMR spectrum recorded on the underivatized asphaltene as a control, carbazole and pyrrole-like nitrogens were the major naturally abundant nitrogens detected. PMID:26556054

  10. Synthesis, characterization and thermodynamics of complex formation of some new Schiff base ligands with some transition metal ions and the adduct formation of zinc Schiff base complexes with some organotin chlorides.

    PubMed

    Asadi, Mozaffar; Asadi, Zahra; Torabi, Susan; Lotfi, Najmeh

    2012-08-01

    Four new complexes, [M(Salpyr)] where Salpyr=N,N'-bis(Salicylidene)-2,3- and 3,4-diiminopyridine and M=Co, Cu, Mn, Ni and Zn were synthesized and characterized by (1)H NMR, IR spectroscopy, elemental analysis and UV-vis spectrophotometry. UV-vis spectrophotometric study of the adduct formation of the zinc(II) complexes, [Zn(2,3-Salpyr)] and [Zn(3,4-Salpyr)], as donor with R(2)SnCl(2) (R=methyl, phenyl, n-butyl), PhSnCl(3) and Bu(3)SnCl as acceptors has been investigated in methanol, as solvent. The formation constants and the thermodynamic free energies were measured using UV-vis spectrophotometry. Titration of the organotin chlorides with Zn(II) complexes at various temperatures (T=283-313K) leads to 1:1 adduct formation. The results show that the formation constants were decreased by increasing the temperature. The trend of the reaction of R(n)SnCl(4-n) as acceptors toward given zinc complexes was as follows: PhSnCl3 > Me2SnCl2 > Ph2SnCl2 > Bu2SnCl2 > Bu3SnCl. By considering the formation constants and the ?G of the complex formation for the Schiff base as donor and the M(II) as acceptor, the following conclusion was drawn: the formation constant for a given Schiff base changes according to the following trend: Ni > Cu > Co > Zn > Mn. PMID:22626922

  11. Synthesis, characterization and thermodynamics of complex formation of some new Schiff base ligands with some transition metal ions and the adduct formation of zinc Schiff base complexes with some organotin chlorides

    NASA Astrophysics Data System (ADS)

    Asadi, Mozaffar; Asadi, Zahra; Torabi, Susan; Lotfi, Najmeh

    Four new complexes, [M(Salpyr)] where Salpyr = N,N'-bis(Salicylidene)-2,3- and 3,4-diiminopyridine and M = Co, Cu, Mn, Ni and Zn were synthesized and characterized by 1H NMR, IR spectroscopy, elemental analysis and UV-vis spectrophotometry. UV-vis spectrophotometric study of the adduct formation of the zinc(II) complexes, [Zn(2,3-Salpyr)] and [Zn(3,4-Salpyr)], as donor with R2SnCl2 (R = methyl, phenyl, n-butyl), PhSnCl3 and Bu3SnCl as acceptors has been investigated in methanol, as solvent. The formation constants and the thermodynamic free energies were measured using UV-vis spectrophotometry. Titration of the organotin chlorides with Zn(II) complexes at various temperatures (T = 283-313 K) leads to 1:1 adduct formation. The results show that the formation constants were decreased by increasing the temperature. The trend of the reaction of RnSnCl4-n as acceptors toward given zinc complexes was as follows: PhSnCl3 > Me2SnCl2 > Ph2SnCl2 > Bu2SnCl2 > Bu3SnCl By considering the formation constants and the ?G of the complex formation for the Schiff base as donor and the M(II) as acceptor, the following conclusion was drawn: the formation constant for a given Schiff base changes according to the following trend: Ni > Cu > Co > Zn > Mn

  12. Schiff base formation and recognition of amino sugars, aminoglycosides and biological polyamines by 2-formyl phenylboronic acid in aqueous solution.

    PubMed

    Gutirrez-Moreno, Nini J; Medrano, Felipe; Yatsimirsky, Anatoly K

    2012-09-14

    Interactions of 2-, 3- and 4-formyl phenylboronic acids (FPBAs) with sugars, amino sugars, aminoglycosides and various poly- and monoamines have been studied by UV-vis, (1)H and (11)B NMR titrations in water at variable pH. Behavior of 2-FPBA was anomalous in several aspects. Transformation of the acid into its conjugate base was slow in NMR time scale and was accompanied by intramolecular cyclization affording the respective benzoboroxole. The equilibrium constants for imine formation (K(imine)) between 2-FPBA and simple monoamines including amino sugars were ca. 2 orders of magnitude larger than those with other isomers. Still one order of magnitude larger K(imine) values were observed for 2-FPBA with aminoglycosides (kanamycin, amikacin, gentamicin, neomycin) and polyamines (spermine, spermidine). The examination of UV-vis and (11)B NMR spectra of imines formed with 2-FPBA showed that formally neutral Schiff bases in fact were zwitterionic species containing a protonated imine group and an anionic B(OH)(3)(-) group. The enhanced stability of imines with monoamines can therefore be attributed to the electrostatic stabilization provided by the zwitterionic structure and further increased stability of imines with antibiotics and polyamines is explicable by additional stabilization of the borate anionic group by ion paring with ammonium groups not involved in Schiff base formation. Thanks to high molar absorptivity of protonated imines interaction of 2-FPBA with aminoglycosides allows detecting them spectrophotometrically in a ?M concentration range in neutral aqueous solutions in the presence of sugars, amino sugars and amino acids. PMID:22842531

  13. Metal complexes of a novel Schiff base derived from sulphametrole and varelaldehyde. Synthesis, spectral, thermal characterization and biological activity

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; Zayed, M. A.; Abdallah, S. M.

    2010-08-01

    Metal complexes of a novel Schiff base (HL = 3-(4'-ethylazomethinobenzene sulphonamide)-4-methoxy-1,2,5-thiadiazole) derived from condensation of sulphametrole and varelaldehyde are reported and characterized based on elemental analyses, IR, solid reflectance, magnetic moment, molar conductance, and thermal analysis (TG). From the elemental analyses data, 1:1 metal complexes are formed having the general formulae [MCl 3(HL)(H 2O)]3H 2O (M = Cr(III), Fe(III)) and [MCl 2(HL)(H 2O) 2] yH 2O (where M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II), y = 0-3). The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied. IR spectra show that HL is coordinated to the metal ions in a neutral bidentate manner with ON donor sites of the enolic sulphonamide- OH and thiodiaza- N. The solid complexes have been synthesized and studied by thermogravimetric analysis. The thermal dehydration and decomposition of these complexes were studied kinetically using the integral method applying the Coats-Redfern equation. All the metal chelates are found to be non-electrolytes. From the magnetic and solid reflectance spectra, the complexes have octahedral structures. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species ( Escherichia coli and Staphylococcus aureus) and fungi ( Candida and Aspergillus flavus). The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species.

  14. Spectral characterization, cyclic voltammetry, morphology, biological activities and DNA cleaving studies of amino acid Schiff base metal(II) complexes.

    PubMed

    Neelakantan, M A; Rusalraj, F; Dharmaraja, J; Johnsonraja, S; Jeyakumar, T; Sankaranarayana Pillai, M

    2008-12-15

    Metal complexes are synthesized with Schiff bases derived from o-phthalaldehyde (opa) and amino acids viz., glycine (gly) l-alanine (ala), l-phenylalanine (pal). Metal ions coordinate in a tetradentate or hexadentate manner with these N(2)O(2) donor ligands, which are characterized by elemental analysis, molar conductance, magnetic moments, IR, electronic, (1)H NMR and EPR spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Based on EPR studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values calculated for copper complexes at 300K and in frozen DMSO (77K) indicate the presence of the unpaired electron in the dx2-y2 orbital. The evaluated metal-ligand bonding parameters showed strong in-plane sigma- and pi-bonding. X-ray diffraction (XRD) and scanning electron micrography (SEM) analysis provide the crystalline nature and the morphology of the metal complexes. The cyclic voltammograms of the Cu(II)/Mn(II)/VO(II) complexes investigated in DMSO solution exhibit metal centered electroactivity in the potential range -1.5 to +1.5V. The electrochemical data obtained for Cu(II) complexes explains the change of structural arrangement of the ligand around Cu(II) ions. The biological activity of the complexes has been tested on eight bacteria and three fungi. Cu(II) and Ni(II) complexes show an increased activity in comparison to the controls. The metal complexes of opapal Schiff base were evaluated for their DNA cleaving activities with calf-thymus DNA (CT DNA) under aerobic conditions. Cu(II) and VO(II) complexes show more pronounced activity in presence of the oxidant. PMID:18656419

  15. Spectral characterization, cyclic voltammetry, morphology, biological activities and DNA cleaving studies of amino acid Schiff base metal(II) complexes

    NASA Astrophysics Data System (ADS)

    Neelakantan, M. A.; Rusalraj, F.; Dharmaraja, J.; Johnsonraja, S.; Jeyakumar, T.; Sankaranarayana Pillai, M.

    2008-12-01

    Metal complexes are synthesized with Schiff bases derived from o-phthalaldehyde (opa) and amino acids viz., glycine (gly) L-alanine (ala), L-phenylalanine (pal). Metal ions coordinate in a tetradentate or hexadentate manner with these N 2O 2 donor ligands, which are characterized by elemental analysis, molar conductance, magnetic moments, IR, electronic, 1H NMR and EPR spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Based on EPR studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values calculated for copper complexes at 300 K and in frozen DMSO (77 K) indicate the presence of the unpaired electron in the d orbital. The evaluated metal-ligand bonding parameters showed strong in-plane σ- and π-bonding. X-ray diffraction (XRD) and scanning electron micrography (SEM) analysis provide the crystalline nature and the morphology of the metal complexes. The cyclic voltammograms of the Cu(II)/Mn(II)/VO(II) complexes investigated in DMSO solution exhibit metal centered electroactivity in the potential range -1.5 to +1.5 V. The electrochemical data obtained for Cu(II) complexes explains the change of structural arrangement of the ligand around Cu(II) ions. The biological activity of the complexes has been tested on eight bacteria and three fungi. Cu(II) and Ni(II) complexes show an increased activity in comparison to the controls. The metal complexes of opapal Schiff base were evaluated for their DNA cleaving activities with calf-thymus DNA (CT DNA) under aerobic conditions. Cu(II) and VO(II) complexes show more pronounced activity in presence of the oxidant.

  16. Synthesis, analgesic, anti-inflammatory and anti-ulcerogenic activities of certain novel Schiff's bases as fenamate isosteres.

    PubMed

    Alafeefy, Ahmed M; Bakht, Mohammed A; Ganaie, Majid A; Ansarie, Mohd N; El-Sayed, Nahed N; Awaad, Amani S

    2015-01-15

    A series of certain novel Schiff bases as fenamate isosteres (VI:a-k) were synthesized to locate analgesic, anti-inflammatory agent with minimal ulcerogenic potential. The structures of the newly synthesized compounds were elucidated on the basis of their elemental analysis as well as IR, and NMR and mass spectroscopic data. All the compounds were evaluated for their anti-inflammatory activity by carrageenan induced paw oedema method. The compounds possessing good anti-inflammatory activity were further tested for analgesic, ulcerogenic, lipid peroxidation potentials and liver toxicity. Compounds (VI-c), (VI-f), (VI-h) and (VI-i) showed the best anti-inflammatory and significant analgesic activities at doses comparable to that of the standard drug Indomethacin. However, compounds (VI-c) and (VI-f) could be considered the most potent anti-inflammatory and analgesic molecules with maximum reduction in gastro-intestinal ulceration with no hepatocyte necrosis or liver degeneration. PMID:25522819

  17. Synthesis, characterization and biological activity of transition metal complexes with Schiff bases derived from 2-nitrobenzaldehyde with glycine and methionine

    NASA Astrophysics Data System (ADS)

    Singh, Bibhesh K.; Rajour, Hemant K.; Prakash, Anant

    Schiff bases derived from 2-nitrobenzaldehyde with amino acids (glycine, methionine) and their Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized by various physico-chemical techniques. From spectral studies, it has been concluded that the ligands acts as bidentate molecule, coordinates metal through azomethine nitrogen and carboxylate oxygen. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML2 complexes. X-ray powder diffraction helps to determine the cell parameters of the complexes. Molecular structure of the complexes has been optimized by MM2 calculations and suggests a square planar geometry. The ligands and their metal complexes have been tested in vitro against Streptococcus, Staph, Staphylococcus aureus and Escherchia coli bacteria in order to assess their antibacterial potential. The results indicate that the biological activity increases on complexation.

  18. Synthesis, Spectral Characterization, and Biological Evaluation of Transition Metal Complexes of Bidentate N, O Donor Schiff Bases

    PubMed Central

    Sumrra, Sajjad Hussain; Ambreen, Sabahat; Imran, Muhammad; Danish, Muhammad; Rehmani, Fouzia Sultana

    2014-01-01

    New series of three bidentate N, O donor type Schiff bases (L1)(L3) were prepared by using ethylene-1,2-diamine with 5-methyl furfural, 2-anisaldehyde, and 2-hydroxybenzaldehyde in an equimolar ratio. These ligands were further complexed with Co(II), Cu(II), Ni(II), and Zn(II) metals to produce their new metal complexes having an octahedral geometry. These compounds were characterized on the basis of their physical, spectral, and analytical data. Elemental analysis and spectral data of the uncomplexed ligands and their metal(II) complexes were found to be in good agreement with their structures, indicating high purity of all the compounds. All ligands and their metal complexes were screened for antimicrobial activity. The results of antimicrobial activity indicated that metal complexes have significantly higher activity than corresponding ligands. This higher activity might be due to chelation process which reduces the polarity of metal ion by coordinating with ligands. PMID:25147493

  19. Synthesis, characterization and biological activity of transition metal complexes with Schiff bases derived from 2-nitrobenzaldehyde with glycine and methionine.

    PubMed

    Singh, Bibhesh K; Rajour, Hemant K; Prakash, Anant

    2012-08-01

    Schiff bases derived from 2-nitrobenzaldehyde with amino acids (glycine, methionine) and their Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized by various physico-chemical techniques. From spectral studies, it has been concluded that the ligands acts as bidentate molecule, coordinates metal through azomethine nitrogen and carboxylate oxygen. Mass spectrum explains the successive degradation of the molecular species in solution and justifies ML(2) complexes. X-ray powder diffraction helps to determine the cell parameters of the complexes. Molecular structure of the complexes has been optimized by MM2 calculations and suggests a square planar geometry. The ligands and their metal complexes have been tested in vitro against Streptococcus, Staph, Staphylococcus aureus and Escherchia coli bacteria in order to assess their antibacterial potential. The results indicate that the biological activity increases on complexation. PMID:22522296

  20. Synthesis, spectroscopic characterization and comparative DNA binding studies of Schiff base complexes derived from L-leucine and glyoxal.

    PubMed

    Shakir, Mohammad; Shahid, Nida; Sami, Naushaba; Azam, Mohammad; Khan, Asad U

    2011-11-01

    The mononuclear Schiff base complexes of the type, [ML(CH(3)OH)(2)] [M = Co(II), Ni(II), Cu(II) and Zn(II)] have been synthesized by template condensation of L-leucine and glyoxal. The complexes have been characterized on the basis of the results of the elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz, FT-IR, Mass, (1)H NMR and (13)C NMR spectra. The UV-vis and magnetic moment data revealed an octahedral geometry around Co(II), Ni(II) ion with distortion around Cu(II) ion complex confirmed by EPR data. The conductivity data show a non-electrolytic nature of the complexes. Absorption and fluorescence spectroscopic studies support that all the complexes exhibit a significant binding to calf thymus DNA. PMID:21807556

  1. Control of biofilm formation in marine environment using some N{sub 2}O{sub 2} donor Schiff bases

    SciTech Connect

    Dubey, R.S.; Dubey, R.S.; Upadhyay, S.N.; Namboodhiri, T.K.G.

    1997-08-01

    The adhesion of microorganisms onto materials surface mediated by extracellular polymeric substances (EPS) lead to an important modification of the metal-solution interface. The requirement of modern civilization with the heightened sense of environmental responsibilities and quality of life can be met by using some eco-friendly microbiocides with different spectra of activity. Some N{sub 2}O{sub 2} donor Schiff base compounds were synthesized and characterized by IR, NMR and ESR spectroscopy. These compounds were found effective in controlling the growth of biofilm of E. coli, Pseudomonas fluorescens and Thiobacillus thiooxidans on copper surface. The optimum concentration of these compounds are in the range of 1--10 ppm. Various electrochemical, microbiological and surface-analytical techniques were used to monitor the biofilm in the presence of microbiocides.

  2. Synthesis, antiviral activity and cytotoxicity evaluation of Schiff bases of some 2-phenyl quinazoline-4(3)H-ones.

    PubMed

    Kumar, Krishnan Suresh; Ganguly, Swastika; Veerasamy, Ravichandran; De Clercq, Erik

    2010-11-01

    A new series of 3-(benzylideneamino)-2-phenylquinazoline-4(3H)-ones were prepared through Schiff base formation of 3-amino-2-phenyl quinazoline-4(3)H-one with various substituted carbonyl compounds. Their chemical structures were elucidated by spectral studies. Cytotoxicity and antiviral activity were evaluated against herpes simplex virus-1 (KOS), herpes simplex virus-2 (G), vaccinia virus, vesicular stomatitis virus, herpes simplex virus-1 TK- KOS ACVr, para influenza-3 virus, reovirus-1, Sindbis virus, Coxsackie virus B4, Punta Toro virus, feline corona virus (FIPV), feline herpes virus, respiratory syncytial virus, influenza A H1N1 subtype, influenza A H3N2 subtype, and influenza B virus. Compound 2a showed better antiviral activity against the entire tested virus. PMID:20724039

  3. Adsorption and inhibitive properties of a Schiff base for the corrosion control of carbon steel in saline water.

    PubMed

    Samide, Adriana; Tutunaru, Bogdan

    2011-01-01

    A Schiff base, namely N-(2-hydroxybenzylidene) thiosemicarbazide (HBTC), was investigated as inhibitor for carbon steel in saline water (SW) using electrochemical measurements such as: potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The morphology of the surfaces before and after corrosion was examined by Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM/EDS). The results showed that HBTC acts as corrosion inhibitor in SW by suppressing simultaneously the cathodic and anodic processes via adsorption on the surface which followed the Langmuir adsorption isotherm; the polarization resistance (R(p)) and inhibition efficiency (IE) increased with each HBTC concentration increase. SEM/EDS analysis showed at this stage that the main product of corrosion is a non-stoichiometric amorphous Fe(3+) oxyhydroxide, consisting of a mixture of Fe(3+) oxyhydroxides, ?-FeOOH and/or ?-FeOOH, ?-FeOOH/?-FeOOH and Fe(OH)(3). PMID:22175875

  4. Fluorescence properties of Schiff base - N,N?-bis(salicylidene) - 1,2-Phenylenediamine in presence of bile acid host

    NASA Astrophysics Data System (ADS)

    Roy, Nayan; Paul, Pradip C.; Singh, T. Sanjoy

    2015-05-01

    Fluorescence properties of Schiff base - N,N?-bis(salicylidene) - 1,2-phenylenediamine (LH2) is used to study the micelles formed by aggregation of different important bile acids like cholic acid, deoxycholic acid, chenodeoxycholic acid and glycocholic acid by steady state and picosecond time-resolved fluorescence spectroscopy. The fluorescence band intensity was found out to increase with concomitant red shift with gradual addition of different bile acids. Binding constant of the probe with different bile acids as well as critical micelle concentration was obtained from the variation of fluorescence intensity on increasing concentration of bile acids in the medium. The increase in fluorescence quantum yields, fluorescence decay times and substantial decrease in nonradiative decay rate constants in bile acids micellar environment points to the restricted motion of the fluorophore inside the micellar subdomains.

  5. Synthesis and characterization of metal complexes of Schiff base ligand derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine

    NASA Astrophysics Data System (ADS)

    Selwin Joseyphus, R.; Shiju, C.; Joseph, J.; Justin Dhanaraj, C.; Arish, D.

    2014-12-01

    The Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from imidazole-2-carboxaldehyde and 4-aminoantipyrine were synthesized. These compounds were characterized by elemental analysis, IR, mass, 1H NMR, electronic spectra, magnetic moment, molar conductance, thermal analysis, powder XRD and SEM. The analytical data show that the metal to ligand ratio is 1:1. The IR results show that the ligand acts as a bidentate donor coordinating through the azomethine nitrogen and imidazole nitrogen atoms. From the electronic spectra and magnetic moment value predicts the geometry of the complexes. The surface morphology of the compounds was studied by SEM. The compounds were screened for their antibacterial activity and antifungal activity using Kirby Bayer disc diffusion method. The DNA cleavage and superoxide dismutase activities of the compounds were investigated. The anticancer activities of the complexes have been carried out towards HeLa and HCT116 cancer cells.

  6. 119Sn Mssbauer characterization of self assembled organotin(IV) complexes with Schiff bases containing amino acetate skeletons

    NASA Astrophysics Data System (ADS)

    Basu, Smita; Mizar, Archana; Baul, Tushar S. Basu; Rivarola, Eleonora

    2008-07-01

    Several organotin(IV) compounds, viz., diorganotin(IV) compounds of the types Ph2SnLH (monomer), nBu2SnLHOH2 (monomer), [Me2SnLHOH2]2 (centrosymmetric dimer), [nBu2SnLH]3 (cyclic trinuclear), [Ph2SnLH] n (polymer), {[nBu2Sn(LH)]2O}2 (centrosymmetric tetranuclear), dinuclear di-/tri-mixed organotin(IV) compounds Ph2SnLHPh3SnCl (monomer) and triorganotin(IV) compounds of the types [Bz3SnLH]2 (centrosymmetric dimer) and [Me3SnL1H] n (Polymer) (LH = Schiff base carboxylate) have been studied in the solid state at liquid nitrogen temperature using 119Sn Mssbauer spectroscopy. The tin coordination geometry of the compounds determined from crystallography was correlated with the 119Sn Mssbauer results.

  7. Synthesis, crystal structure, IR, 1H NMR and theoretical calculations of 1,2,4-triazole Schiff base

    NASA Astrophysics Data System (ADS)

    Jin, R. Y.; Sun, X. H.; Liu, Y. F.; Long, W.; Lu, W. T.; Ma, H. X.

    2014-03-01

    5-Propyl-4-amino-1,2,4-triazole Schiff base was characterized by FT-IR, 1H NMR and X-ray single crystal diffraction techniques. The compound crystallizes in the triclinic space group p-1 with z = 2. The molecular geometry was optimized using density functional theory (DFT/B3LYP) and hartree fock (HF) methods with the 6-311G+(d,p) and 6-311G basis set in ground state. From the optimized geometry of the molecule, vibrational frequencies, HOMO-LUMO and natural bond orbital (NBO) were calculated with B3LYP/6-311G+(d,p) level. In addition, gauge independent atomic orbital (GIAO) 1H NMR chemical shift values was calculated at B3LYP/6-311G+(d,p) and HF/6-311G+(d,p) level.

  8. Molecular engineering of Schiff-base linked covalent polymers with diverse topologies by gas-solid interface reaction.

    PubMed

    Liu, Xuan-He; Guan, Cui-Zhong; Zheng, Qing-Na; Wang, Dong; Wan, Li-Jun

    2015-03-14

    The design and construction of molecular nanostructures with tunable topological structures are great challenges in molecular nanotechnology. Herein, we demonstrate the molecular engineering of Schiff-base bond connected molecular nanostructures. Building module construction has been adopted to modulate the symmetry of resulted one dimensional (1D) and two dimensional (2D) polymers. Specifically, we have designed and constructed 1D linear and zigzag polymers, 2D hexagonal and chessboard molecular nanostructures by varying the number of reactive sites and geometry and symmetry of precursors. It is demonstrated that high-quality conjugated polymers can be fabricated by using gas-solid interface reaction. The on-demanding synthesis of polymeric architectures with diverse topologies paves the way to fabricate molecular miniature devices with various desired functionalities. PMID:25770494

  9. Molecular engineering of Schiff-base linked covalent polymers with diverse topologies by gas-solid interface reaction

    NASA Astrophysics Data System (ADS)

    Liu, Xuan-He; Guan, Cui-Zhong; Zheng, Qing-Na; Wang, Dong; Wan, Li-Jun

    2015-03-01

    The design and construction of molecular nanostructures with tunable topological structures are great challenges in molecular nanotechnology. Herein, we demonstrate the molecular engineering of Schiff-base bond connected molecular nanostructures. Building module construction has been adopted to modulate the symmetry of resulted one dimensional (1D) and two dimensional (2D) polymers. Specifically, we have designed and constructed 1D linear and zigzag polymers, 2D hexagonal and chessboard molecular nanostructures by varying the number of reactive sites and geometry and symmetry of precursors. It is demonstrated that high-quality conjugated polymers can be fabricated by using gas-solid interface reaction. The on-demanding synthesis of polymeric architectures with diverse topologies paves the way to fabricate molecular miniature devices with various desired functionalities.

  10. Interaction of three new tetradentates Schiff bases containing N2O2 donor atoms with calf thymus DNA.

    PubMed

    Ajloo, Davood; Shabanpanah, Sajede; Shafaatian, Bita; Ghadamgahi, Maryam; Alipour, Yasin; Lashgarbolouki, Taghi; Saboury, Ali Akbar

    2015-01-01

    Interaction of 1,3-bis(2-hydroxy-benzylidene)-urea (H2L1), 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea (H2L2) and 1,3-bis(2-hydroxy-3-methoxy-benzylidene)-urea nickel(II) (NiL2) with calf-thymus DNA were investigated by UV-vis absorption, fluorescence emission and circular dichroism (CD) spectroscopy as well as cyclic voltammetry, viscosity measurements, molecular docking and molecular dynamics simulation. Binding constants were determined using UV-vis absorption and fluorescence spectra. The results indicated that studied Schiff-bases bind to DNA in the intercalative mode in which the metal derivative is more effective than non metals. Their interaction trend is further determined by molecular dynamics (MD) simulation. MD results showed that Ni derivative reduces oligonucleotide intermolecular hydrogen bond and increases solvent accessible surface area more than other compounds. PMID:25796450

  11. Solution combustion synthesis using Schiff-base aluminum complex without fuel and optical property investigations of alumina nanoparticles

    NASA Astrophysics Data System (ADS)

    Salehi, Mehdi; Arabsarhangi, Ehsan

    2015-05-01

    Synthesis of alumina nanomaterials via a solution combustion technique using Schiff base aluminum (III) complex at 820 and 950 C for 4 h was performed successfully. The synthesis procedure was performed using the complex in the absence and presence of urea and glycine as fuel for comparison. The obtained data showed that the procedure without using fuel resulted in a better phase and morphology. To investigate the phase formation, powder X-ray diffraction technique was used. Also, SEM micrographs were used to investigate the morphology of the obtained materials. The optical properties of the obtained materials were studied by FTIR spectra. According to the PXRD data, it was found that with annealing at 950 C, the phase formation of the obtained materials showed cubic crystal structure with cell parameter a = 3.14 for gamma phase. Also, by annealing at 820 C using fuels for 4 h, the main phase was found to be in gamma.

  12. (E)3-2-(1-(2,4-Dihydroxyphenyl)ethyldeneamino)phenyl)-2-methylquinazoline-4(3H)-one Schiff Base and Its Metal Complexes: A New Drug of Choice against Methicillin-Resistant Staphylococcus aureus

    PubMed Central

    Siddappa, K.; Mane, Sunilkumar B.; Manikprabhu, Deene

    2014-01-01

    The 3-(2-aminophenyl) quinazolin-2-methyl-4(3H)-one and 2,4-dihydroxyacetophenone undergo condensation to afford (E)3-2-(1-(2,4-dihydroxyphenyl)ethyldeneamino)phenyl)-2-methylquinazoline-4(3H)-one Schiff base (DHPEAPMQ). The newly synthesized Schiff base (DHPEAPMQ) and its metal complexes were evaluated for their antimicrobial activity against methicillin-resistant Staphylococcus aureus isolated from the Gulbarga region in India. The Cu(II), Ni(II), and Zn(II) complexes of Schiff base (DHPEAPMQ) showed good antimicrobial activity. So, this could be a new drug of choice. PMID:24733996

  13. Crystal Structure, Cytotoxicity and Interaction with DNA of Zinc (II) Complexes with o-Vanillin Schiff Base Ligands

    PubMed Central

    Niu, Mei-Ju; Li, Zhen; Chang, Guo-Liang; Kong, Xiang-Jin; Hong, Min; Zhang, Qing-fu

    2015-01-01

    Two new zinc complexes, Zn(HL1)2 (1) and [Zn2(H2L2)(OAc)2]2 (2) [H2L1 = Schiff base derived from o-vanillin and (R)-(+)-2-amino-3-phenyl-1-propanol, H3L2 = Schiff base derived from o-vanillin and 2-amino-2-ethyl-1,3-propanediol], have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, TG analyses, solid fluorescence, IR, UV-Vis and circular dichroism spectra. The structural analysis shows that complex 1 has a right-handed double helical chain along the crystallographic b axis. A homochiral 3D supramolecular architecture has been further constructed by intermolecular C-H··· π, O-H···O and C-H···O interactions. Complex 2 includes two crystallographically independent binuclear zinc molecules. The two binuclear zinc molecules are isostructural. The 2-D sheet supramolecular structure was formed by intermolecular hydrogen bonding interaction. The fluorescence of ligands and complexes in DMF at room temperature are studied. The interactions of two complexes with calf thymus DNA (CT-DNA) are investigated using UV-Vis, CD and fluorescence spectroscopy. The results show that complex 1 exhibits higher interaction with CT-DNA than complex 2. In addition, in vitro cytotoxicity of the complexes towards four kinds of cancerous cell lines (A549, HeLa, HL-60 and K562) were assayed by the MTT method. Investigations on the structures indicated that the chirality and nuclearity of zinc complexes play an important role on cytotoxic activity. PMID:26114437

  14. Structural investigation of oxovanadium(IV) Schiff base complexes: X-ray crystallography, electrochemistry and kinetic of thermal decomposition

    NASA Astrophysics Data System (ADS)

    Asadi, Mozaffar; Asadi, Zahra; Savaripoor, Nooshin; Dusek, Michal; Eigner, Vaclav; Shorkaei, Mohammad Ranjkesh; Sedaghat, Moslem

    2015-02-01

    A series of new VO(IV) complexes of tetradentate N2O2 Schiff base ligands (L1-L4), were synthesized and characterized by FT-IR, UV-vis and elemental analysis. The structure of the complex VOL1?DMF was also investigated by X-ray crystallography which revealed a vanadyl center with distorted octahedral coordination where the 2-aza and 2-oxo coordinating sites of the ligand were perpendicular to the "-yl" oxygen. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO < H < Br < Cl. We also studied the thermodynamics of formation of the complexes and kinetic aspects of their thermal decomposition. The formation constants with various substituents on the aldehyde ring follow the trend 5-OMe > 5-H > 5-Br > 5-Cl. Furthermore, the kinetic parameters of thermal decomposition were calculated by using the Coats-Redfern equation. According to the Coats-Redfern plots the kinetics of thermal decomposition of studied complexes is of the first-order in all stages, the free energy of activation for each following stage is larger than the previous one and the complexes have good thermal stability. The preparation of VOL1?DMF yielded also another compound, one kind of vanadium oxide [VO]X, with different habitus of crystals, (platelet instead of prisma) and without L1 ligand, consisting of a V10O28 cage, diaminium moiety and dimethylamonium as a counter ions. Because its crystal structure was also new, we reported it along with the targeted complex.

  15. Structural investigation of oxovanadium(IV) Schiff base complexes: X-ray crystallography, electrochemistry and kinetic of thermal decomposition.

    PubMed

    Asadi, Mozaffar; Asadi, Zahra; Savaripoor, Nooshin; Dusek, Michal; Eigner, Vaclav; Shorkaei, Mohammad Ranjkesh; Sedaghat, Moslem

    2015-02-01

    A series of new VO(IV) complexes of tetradentate N2O2 Schiff base ligands (L(1)-L(4)), were synthesized and characterized by FT-IR, UV-vis and elemental analysis. The structure of the complex VOL(1)?DMF was also investigated by X-ray crystallography which revealed a vanadyl center with distorted octahedral coordination where the 2-aza and 2-oxo coordinating sites of the ligand were perpendicular to the "-yl" oxygen. The electrochemical properties of the vanadyl complexes were investigated by cyclic voltammetry. A good correlation was observed between the oxidation potentials and the electron withdrawing character of the substituents on the Schiff base ligands, showing the following trend: MeO5-H>5-Br>5-Cl. Furthermore, the kinetic parameters of thermal decomposition were calculated by using the Coats-Redfern equation. According to the Coats-Redfern plots the kinetics of thermal decomposition of studied complexes is of the first-order in all stages, the free energy of activation for each following stage is larger than the previous one and the complexes have good thermal stability. The preparation of VOL(1)?DMF yielded also another compound, one kind of vanadium oxide [VO]X, with different habitus of crystals, (platelet instead of prisma) and without L(1) ligand, consisting of a V10O28 cage, diaminium moiety and dimethylamonium as a counter ions. Because its crystal structure was also new, we reported it along with the targeted complex. PMID:25448962

  16. A comparative study of cytotoxicity and interaction with DNA/protein of five transition metal complexes with Schiff base ligands.

    PubMed

    Niu, Meiju; Hong, Min; Chang, Guoliang; Li, Xiao; Li, Zhen

    2015-07-01

    Five transition metal complexes NiL(1)2 (1), CuL(1)2 (2), ZnL(1)2 (3), [MnL(1)2(N3)]nnCH2Cl2 (4), CuL(2)2 (5) {HL(1)=3-{[2-(2-hydroxy-ethoxy)-ethylimino]-methyl}-naphthalen-2-ol, HL(2)=2-{[2-(2-hydroxy-ethoxy)-ethylimino]-methyl}-phenol} have been synthesized and fully characterized. In all of the complexes, the ligands coordinated to the metal ion in a negative fashion via O and N donor atoms. The X-ray structures of nickel complex 1 and copper complexes 2 and 5 are four-coordinated monomers and show slightly distorted square-planar geometry in the vicinity of the central metal atom. Zinc complex 3 exhibits a four-coordinated tetrahedral structure. Differently, manganese complex 4 reveals a six-coordinated octahedral structure, one-dimensional chain is linked by azide in the end-to-end mode. In vitro cytotoxicity of these complexes to various tumor cell lines was assayed by the MTT method. The results showed that most of these metal-Schiff base complexes exhibited enhanced cytotoxicity than Schiff base ligands, which clearly implied a positive synergistic effect. Moreover, these complexes appeared to be selectively active against certain cell lines. The interactions of these metal complexes with CT-DNA were investigated by UV-vis, fluorescence and CD spectroscopy, the results indicated that these complexes are metallointercalators and can interact with CT-DNA. The study of interaction between complexes and BSA indicated that all of the complexes could quench the intrinsic fluorescence of BSA in a static quenching process. PMID:25974907

  17. Connectivity of the retinal Schiff base to Asp85 and Asp96 during the bacteriorhodopsin photocycle: the local-access model.

    PubMed Central

    Brown, L S; Dioumaev, A K; Needleman, R; Lanyi, J K

    1998-01-01

    In the recently proposed local-access model for proton transfers in the bacteriorhodopsin transport cycle (Brown et al. 1998. Biochemistry. 37:3982-3993), connection between the retinal Schiff base and Asp85 (in the extracellular direction) and Asp96 (in the cytoplasmic direction)is maintained as long as the retinal is in its photoisomerized state. The directionality of the proton translocation is determined by influences in the protein that make Asp85 a proton acceptor and, subsequently, Asp96 a proton donor. The idea of concurrent local access of the Schiff base in the two directions is now put to a test in the photocycle of the D115N/D96N mutant. The kinetics had suggested that there is a single sequence of intermediates, L<-->M1<-->M2<-->N, and the M2-->M1 reaction depends on whether a proton is released to the extracellular surface. This is now confirmed. We find that at pH 5, where proton release does not occur, but not at higher pH, the photostationary state created by illumination with yellow light contains not only the M1 and M2 states, but also the L and the N intermediates. Because the L and M1 states decay rapidly, they can be present only if they are in equilibrium with later intermediates of the photocycle. Perturbation of this mixture with a blue flash caused depletion of the M intermediate, followed by its partial recovery at the expense of the L state. The change in the amplitude of the C=O stretch band at 1759 cm-1 demonstrated protonation of Asp85 in this process. Thus, during the reequilibration the Schiff base lost its proton to Asp85. Because the N state, also present in the mixture, arises by protonation of the Schiff base from the cytoplasmic surface, these results fulfill the expectation that under the conditions tested the extracellular access of the Schiff base would not be lost at the time when there is access in the cytoplasmic direction. Instead, the connectivity of the Schiff base flickers rapidly (with the time constant of the M1<-->M2 equilibration) between the two directions during the entire L-to-N segment of the photocycle. PMID:9726947

  18. DNA nanostructures based biosensor for the determination of aromatic compounds.

    PubMed

    Gayathri, S Baby; Kamaraj, P; Arthanareeswari, M; Devikala, S

    2015-10-15

    Graphite electrode was modified using multi-walled carbon nanotubes (MWCNT), chitosan (CS), glutaraldehyde (GTA) and DNA nanostructures (nsDNA). DNA nanostructures of 50 nm in size were produced from single DNA template sequence using a simple two step procedure and were confirmed using TEM and AFM analysis. The modified electrode was applied to the electrochemical detection of aromatic compounds using EIS. The modified electrode was characterized using differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). For comparison, electrochemical results derived from single stranded (50 bp length) and double stranded (50 bp length) DNA based biosensors were used. The results indicate that the modified electrode prior to nsDNA immobilization provides a viable platform that effectively promotes electron transfer between nsDNA and the electrode. The mode of binding between the nsDNA and aromatic compounds was investigated using EIS, indicating that the dominant interaction is non-covalent. nsDNA based biosensor was observed to act as an efficient biosensor in selective and sensitive identification of aromatic compounds. PMID:25982727

  19. Matrix-isolation FT-IR and theoretical investigation of the vibrational properties of the sterically hindered ortho-hydroxy acylaromatic Schiff bases

    NASA Astrophysics Data System (ADS)

    Pajak, J.; Maes, G.; De Borggraeve, W. M.; Boens, N.; Filarowski, A.

    2007-11-01

    FT-IR and FT-Raman spectra of the ortho-hydroxy acylaromatic Schiff bases (2-(α-( N-methylimino)ethyl)-4-chloro-6-nitrophenol - I, 2-(α-( N-methylimino)ethyl)-4,6-dichlorophenol - II), and their isotoposubstitutions have been recorded in the range of 4000-50 cm -1. The spectra were interpreted by a normal coordinate analysis based on B3LYP/6-31++G(d,p) density functional calculations and experimental deuterosubstitution. Proton transfer equilibrium between the enolic and keto tautomers of two sterically hindered Schiff bases has been studied combined experimental (FT-IR matrix-isolation and FT-Raman) and theoretical (DFT/B3LYP/6-31++G(d,p)) methods.

  20. Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole

    NASA Astrophysics Data System (ADS)

    Kalanithi, M.; Rajarajan, M.; Tharmaraj, P.; Sheela, C. D.

    2012-02-01

    Tridentate chelate complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the chalcone based ligands 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-(phenylallyl)]phenol( HL1), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol( HL2), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol( HL3). Microanalytical data, UV-vis spectrophotometric method, magnetic susceptibility measurements, IR, 1H NMR, Mass, and EPR techniques were used to characterize the structure of chelates. The electronic absorption spectra and magnetic susceptibility measurements suggest a distorted square planar geometry for the copper(II) ion. The other metal complexes show distorted tetrahedral geometry. The coordination of the ligands with metal(II) ions was further confirmed by solution fluorescence spectrum. The antimicrobial activity of the ligands and metal(II) complexes against the species Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Candida albigans and Aspergillus niger has been carried out and compared. The electrochemical behavior of copper(II) complex is studied by cyclic voltammetry.

  1. Coordination behavior of new bis Schiff base ligand derived from 2-furan carboxaldehyde and propane-1,3-diamine. Spectroscopic, thermal, anticancer and antibacterial activity studies.

    PubMed

    Mohamed, Gehad G; Zayed, Ehab M; Hindy, Ahmed M M

    2015-06-15

    Novel bis Schiff base ligand, [N1,N3-bis(furan-2-ylmethylene)propane-1,3-diamine], was prepared by the condensation of furan-2-carboxaldehyde with propane-1,3-diamine. Its conformational changes on complexation with transition metal ions [Co(II), Ni(II), Cu(II), Mn(II), Cd(II), Zn(II) and Fe(III)] have been studied on the basis of elemental analysis, conductivity measurements, spectral (infrared, (1)H NMR, electronic), magnetic and thermogravimetric studies. The conductance data of the complexes revealed their electrolytic nature suggesting them as 1:2 (for bivalent metal ions) and 1:3 (for Fe(III) ion) electrolytes. The complexes were found to have octahedral geometry based on magnetic moment and solid reflectance measurements. Thermal analysis data revealed the decomposition of the complexes in successive steps with the removal of anions, coordinated water and bis Schiff base ligand. The thermodynamic parameters were calculated using Coats-Redfern equation. The Anticancer screening studies were performed on human colorectal cancer (HCT), hepatic cancer (HepG2) and breast cancer (MCF-7) cell lines. The antimicrobial activity of all the compounds was studied against Gram negative (Escherichia coli and Proteus vulgaris) and Gram positive (Bacillus vulgaris and Staphylococcus pyogones) bacteria. It was observed that the coordination of metal ion has a pronounced effect on the microbial activities of the bis Schiff base ligand. All the metal complexes have shown higher antimicrobial effect than the free bis Schiff base ligand. PMID:25767990

  2. Chiral discrimination asserted by enantiomers of Ni (II), Cu (II) and Zn (II) Schiff base complexes in DNA binding, antioxidant and antibacterial activities

    NASA Astrophysics Data System (ADS)

    Khan, Noor-ul Hasan; Pandya, Nirali; Prathap, K. Jeya; Kureshy, Rukhsana Ilays; Abdi, Sayed Hasan Razi; Mishra, Sandhya; Bajaj, Hari Chandra

    2011-10-01

    Chiral Schiff base ligands ( S)-H 2L and ( R)-H 2L and their complexes ( S-Ni-L, R-Ni-L, S-Cu-L, R-Cu-L, S-Zn-L and R-Zn-L) were synthesized, characterized and examined for their DNA binding, antioxidant and antibacterial activities. The complexes showed higher binding affinity to calf thymus DNA with binding constant ranging from 2.0 10 5 to 4.5 10 6 M -1. All the complexes also exhibited remarkable superoxide (56-99%) and hydroxyl scavenging (45-89%) activities as well as antibacterial activities against gram (+) and gram (-) bacteria. However, none of the complexes showed antifungal activity. Conclusively, S enantiomers of the complexes were found to be relatively more efficient for DNA interaction, antioxidant and antibacterial activities than their R enantiomers. This study reveals the possible utilization of chiral Schiff base complexes for pharmaceutical applications.

  3. Synthesis, spectroscopic characterization, potentiometric studies, cytotoxic studies and molecular docking studies of DNA binding of transition metal complexes with 1,1-diaminopropane-Schiff base

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; El-Sayed, Badr A.; El-Henawy, Ahmed A.; Ammar, Reda A. A.

    2013-03-01

    A new series of Schiff base transition metal complexes with N,N'-bis(2-hydroxybenzylidene)-1,1-diaminopropane (H2BHBDAP) have been prepared and characterized by elemental analysis, spectroscopic and magnetic measurements. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 C and ionic strength 0.10 M sodium perchlorate. Quantum chemical calculations were performed with semi-empirical method to find the optimum geometry of the ligand and its complexes. Additionally in silico, the Docking studies and the calculated pharmacokinetic parameters show promising futures for application of the ligand and complexes as high potency agents for DNA binding activity.

  4. Synthesis Characterization and Biological Activity Study of New Schiff and Mannich Bases and Some Metal Complexes Derived from Isatin and Dithiooxamide

    PubMed Central

    Abdulghani, Ahlam J.; Abbas, Nada M.

    2011-01-01

    Two new Schiff and Mannich bases, namely, 1-Morpholinomethyl-3(1′ -N-dithiooxamide)iminoisatin (LIH) and 1-diphenylaminomethyl-3-1′-N-dithiooxamide)iminoisatin (LIIH), were prepared from condensation reaction of new Schiff base 3-(1′-N-dithiooxamide)iminoisatin (SBH) with morpholine or diphenylamine respectively in presence of formaldehyde . The structures were characterized by IR, 1HNMR, mass spectrometry, and CHN analyses. Metal complexes of the two ligands were synthesized, and their structures were characterized by elemental analyses, atomic absorption, IR and UV-visible spectra, molar conductivity, and magnetic moment determination. All complexes showed octahedral geometries except palladium complexes which were square planar. The biological activity of the prepared compounds and some selected metal complexes was tested against three types of bacteria and against cell line of human epidermoid larynx carcinoma (Hep-2). PMID:21949661

  5. Syntheses, characterization, biological activity and fluorescence properties of bis-(salicylaldehyde)-1,3-propylenediimine Schiff base ligand and its lanthanide complexes

    NASA Astrophysics Data System (ADS)

    Taha, Ziyad A.; Ajlouni, Abdulaziz M.; Al-Hassan, Khader A.; Hijazi, Ahmed K.; Faiq, Ari B.

    2011-10-01

    Eight new lanthanide metal complexes [Ln L(NO 3) 2]NO 3 {Ln(III) = Nd, Dy, Sm, Pr, Gd, Tb, La and Er, L = bis-(salicyladehyde)-1,3-propylenediimine Schiff base ligand} were prepared. These complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), molar conductivity measurements and spectral studies ( 1H NMR, FT-IR, UV-vis, and luminescence). The Schiff base ligand coordinates to Ln(III) ion in a tetra-dentate manner through the phenolic oxygen and azomethine nitrogen atoms. The coordination number of eight is achieved by involving two bi-dentate nitrate groups in the coordination sphere. Sm, Tb and Dy complexes exhibit the characteristic luminescence emissions of the central metal ions attributed to efficient energy transfer from the ligand to the metal center. Most of the complexes exhibit antibacterial activity against a number of pathogenic bacteria.

  6. Investigation of the active site at the deuterated Schiff-base complex formed between the coenzyme vitamin B 6 and the primary amine

    NASA Astrophysics Data System (ADS)

    Lee, Min-Hee; Kim, Bo-Ra; Kim, Ho-Tae

    2007-07-01

    The Schiff-base complex ion formed between the vitamin B 6 molecule and the primary amine was investigated by electrospray ionization MS/MS in the gas phase. The two observed fragments at the MS/MS spectrum were different from the normal alkene loss (Onium reaction or McLafferty rearrangement) fragments of immonium ions. The R-CH-ND loss fragment from the 3H/D-deuterated Schiff-base complex ion was observed as one of two fragments in the MS/MS spectrum. The R-CH-ND loss fragment is thought to have originated from the simultaneous effect of a 3-OH functional group and a pyridine ring in the immonium ion.

  7. Zn(II), Ni(II), Cu(II) and Pb(II) complexes of tridentate asymmetrical Schiff base ligands: Synthesis, characterization, properties and biological activity

    NASA Astrophysics Data System (ADS)

    Şahin, Mustafa; Koçak, Nuriye; Erdenay, Damla; Arslan, Uğur

    2013-02-01

    New asymmetrical tridentate Schiff base ligands were synthesized using 1,2-phenylenediamine, 4-methyl-1,2-phenylenediamine, 2-hydroxy-1-napthaldehyde, 9-anthracenecarboxaldehyde. Schiff base ligands and their metal complexes were synthesised and characterized by using FT-IR, 1H NMR, 13C NMR, UV-Vis, XRD, ESR, elemental analysis and fluorescence studies. The antimicrobial activity of the ligands and their metal complexes were studied against Staphylococcus aureus ATCC 29213, S. aureus ATCC 25923, Streptococcus mutans RSHM 676, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853. The determination of the antibacterial activity was done using the broth microdilution methods. In general, it has been determined that the studied compounds have MIC values similar to Gram-positive and Gram-negative bacteria. It has been found that Ni, Pb, Zn derivatives of HL1A and ZnL2A has lower MIC values than ampicillin for P. aeruginosa ATCC 27853 strain.

  8. Mn(II) and Cu(II) complexes of a bidentate Schiff's base ligand: Spectral, thermal, molecular modelling and mycological studies

    NASA Astrophysics Data System (ADS)

    Tyagi, Monika; Chandra, Sulekh; Tyagi, Prateek

    2014-01-01

    Complexes of manganese(II) and copper(II) of general composition M(L)2X2 have been synthesized [L = 2-acetyl thiophene thiosemicarbazone and X = Cl- and NO3-]. The elemental analysis, molar conductance measurements, magnetic susceptibility measurements, mass, IR, UV, NMR and EPR spectral studies of the compounds led to the conclusion that the ligand acts as a bidentate manner. The Schiff's base ligand forms hexacoordinated complexes having octahedral geometry for Mn(II) and tetragonal geometry for Cu(II) complexes. The thermal studies suggested that the complexes are more stable as compared to ligand. In molecular modelling the geometries of Schiff's base and metal complexes were fully optimized with respect to the energy using the 6-31g(d,p) basis set. The mycological studies of the compounds were examined against the plant pathogenic fungi i.e. Rhizoctonia bataticola, Macrophomina phaseolina, Fusarium odum.

  9. Synthesis, characterization, in vitro antimicrobial and DNA cleavage studies of Co(II), Ni(II) and Cu(II) complexes with ONOO donor coumarin Schiff bases

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Unki, Shrishila N.; Kulkarni, Ajaykumar D.; Naik, Vinod H.; Badami, Prema S.

    2011-01-01

    A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized with Schiff bases derived from 2-hydroxy-1-naphthaldehyde and 2-oxo-2H-chromene-3-carbohydrazide/6-bromo-2-oxo-2H-chromene-3-carbohydrazide. The chelation of the complexes has been proposed in the light of analytical, spectral (IR, UV-Vis, 1H NMR, ESR, FAB-mass and fluorescence), magnetic and thermal studies. The measured molar conductance values indicate that, the complexes are non-electrolytic in nature. The redox behavior of the complexes was investigated with electrochemical method by using cyclic voltammetry. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial ( Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal activities ( Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The DNA cleavage is studied by agarose gel electrophoresis method.

  10. Diorganotin(IV) complexes of biologically potent 4(3H)-quinazolinone derived Schiff bases: synthesis, spectroscopic characterization, DNA interaction studies and antimicrobial activity.

    PubMed

    Prasad, Kollur Shiva; Kumar, Linganna Shiva; Chandan, Shivamallu; Jayalakshmi, Basvegowda; Revanasiddappa, Hosakere D

    2011-10-15

    Four Schiff base ligands and their corresponding organotin(IV) complexes have been synthesized and characterized by elemental analyses, IR, (1)H NMR, MS and thermal studies. The Schiff bases are obtained by the condensation of 3-amino-2-methyl-4(3H)-quinazolinone with different substituted aldehydes. The elemental analysis data suggest the stoichiometry to be 1:1 ratio formation. Infrared spectral data agreed with the coordination to the central metal ion through imine nitrogen, lactam oxygen and deprotonated phenolic oxygen atoms. All the synthesized compounds have been evaluated for antimicrobial activity against selected species of microorganisms. In addition, DNA binding/cleavage capacity of the compounds was analyzed by absorption spectroscopy, viscosity measurements and gel electrophoresis methods. PMID:21741298

  11. Diorganotin(IV) complexes of biologically potent 4( 3H)-quinazolinone derived Schiff bases: Synthesis, spectroscopic characterization, DNA interaction studies and antimicrobial activity

    NASA Astrophysics Data System (ADS)

    Prasad, Kollur Shiva; Kumar, Linganna Shiva; Chandan, Shivamallu; Jayalakshmi, Basvegowda; Revanasiddappa, Hosakere D.

    2011-10-01

    Four Schiff base ligands and their corresponding organotin(IV) complexes have been synthesized and characterized by elemental analyses, IR, 1H NMR, MS and thermal studies. The Schiff bases are obtained by the condensation of 3-amino-2-methyl-4( 3H)-quinazolinone with different substituted aldehydes. The elemental analysis data suggest the stoichiometry to be 1:1 ratio formation. Infrared spectral data agreed with the coordination to the central metal ion through imine nitrogen, lactam oxygen and deprotonated phenolic oxygen atoms. All the synthesized compounds have been evaluated for antimicrobial activity against selected species of microorganisms. In addition, DNA binding/cleavage capacity of the compounds was analyzed by absorption spectroscopy, viscosity measurements and gel electrophoresis methods.

  12. Novel tandem synthesis of bis(?-NN'-tetrazolate) bridged dinuclear nickel(ii) Schiff base complex via [3 + 2] cyclo-addition at ambient condition.

    PubMed

    Das, Mithun; Harms, Klaus; Chattopadhyay, Shouvik

    2014-04-21

    A novel bis(?-NN'-tetrazolate) bridged centrosymmetric dinuclear nickel(ii) Schiff base complex [Ni2(L)2(PTZ)2]2H2O2CH3CN (HL is a tridentate Schiff base, 2-((2-(ethylamino)ethylimino)methyl)-6-methoxyphenol and HPTZ is 5-pyrazinyltetrazole) has been synthesized via [3 + 2] cyclo-addition reaction of 2-cyanopyrazine and sodium azide in presence of nickel(ii) acetate tetrahydrate and HL. The structure of the complex is confirmed by single crystal X-ray diffraction analysis. The combination of H-bonding and C-H? interactions creates a 3(6)-hxl topological supramolecular network. The acetonitrile molecules are encapsulated as a hydrophobic guest within the 2D supramolecular network. PMID:24577138

  13. Synthesis, characterization and biological activity of some transition metals with Schiff base derived from 2-thiophene carboxaldehyde and aminobenzoic acid

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; Omar, M. M.; Hindy, Ahmed M. M.

    2005-12-01

    Metal complexes of Schiff base derived from 2-thiophene carboxaldehyde and 2-aminobenzoic acid (HL) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The ligand dissociation as well as the metal-ligand stability constants were calculated pH metrically at 25 C and ionic strength ? = 0.1 (1 M NaCl). The complexes are found to have the formulae [M(HL) 2](X) n yH 2O (where M = Fe(III) (X = Cl, n = 3, y = 3), Co(II) (X = Cl, n = 2, y = 1.5), Ni(II) (X = Cl, n = 2, y = 1) and UO 2(II) (X = NO 3, n = 2, y = 0)) and [M(L) 2] (where M = Cu(II) (X = Cl) and Zn(II) (X = AcO)). The molar conductance data reveal that Fe(III) and Co(II), Ni(II) and UO 2(II) chelates are ionic in nature and are of the type 3:1 and 2:1 electrolytes, respectively, while Cu(II) and Zn(II) complexes are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a terdentate manner with ONS donor sites of the carboxylate O, azomethine N and thiophene S. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, ? H*, ? S* and ? G* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.

  14. Structure-property relationship of highly π-conjugated Schiff-base moiety in liquid crystal diepoxide polymerization and mesophases stabilization.

    PubMed

    Liu, Huan; Fu, Zien; Xu, Kai; Cai, Hualun; Liu, Xin; Chen, Mingcai

    2011-06-16

    A study of the structure-property relationship of the highly π-conjugated Schiff-base moiety in polymerization of a liquid crystal (LC) diepoxide oligomer (PBMBA) and mesophases stabilization has been investigated. We first proposed two exothermic peaks distinctly observed in nonisothermal polymerization curves for thermal copolymerization of PBMBA monomer with a diamine comonomer that corresponded to two different reactions, namely, an epoxy-amine polymerization and anionic polymerization. For PBMBA, note that an unexpected homopolymerization accompanying an appearance of enantiotropic mesophase transitions had taken place in the absence of any initiators, evidencing the possibility of an anionic mechanism yielding a homopolymer. A novel Schiff-base model compound (SBM) was synthesized and used to induce the polymerization of different types of epoxies. Based on the structure-property relationship, we considered a specific role of highly π-conjugated Schiff-base moieties in the anionic polymerization of PBMBA and hoped the mesophases could be stabilized using this mechanism, which may provide a key strategy for design of the polymer-dispersed liquid crystal (PDLC) materials via a chemical process. PMID:21604795

  15. Synthesis, characterization and biological activity of some platinum(II) complexes with Schiff bases derived from salicylaldehyde, 2-furaldehyde and phenylenediamine

    NASA Astrophysics Data System (ADS)

    Gaballa, Akmal S.; Asker, Mohsen S.; Barakat, Atiat S.; Teleb, Said M.

    2007-05-01

    Four platinum(II) complexes of Schiff bases derived from salicylaldehyde and 2-furaldehyde with o- and p-phenylenediamine were reported and characterized based on their elemental analyses, IR and UV-vis spectroscopy and thermal analyses (TGA). The complexes were found to have the general formula [Pt(L)(H 2O) 2]Cl 2 nH 2O (where n = 0 for complexes 1, 3, 4; n = 1 for complex 2. The data obtained show that Schiff bases were interacted with Pt(II) ions in the neutral form as a bidentate ligand and the oxygens rather than the nitrogens are the most probable coordination sites. Square planar geometrical structure with two coordinated water molecules were proposed for all complexes The free ligands, and their metal complexes were screened for their antimicrobial activities against the following bacterial species: E. coli, B. subtilis, P. aereuguinosa, S. aureus; fungus A. niger, A. fluves; and the yeasts C. albican, S. cervisiea. The activity data show that the platinum(II) complexes are more potent antimicrobials than the parent Schiff base ligands against one or more microorganisms.

  16. Studies on DNA binding behaviour of biologically active transition metal complexes of new tetradentate N2O2 donor Schiff bases: Inhibitory activity against bacteria

    NASA Astrophysics Data System (ADS)

    Sobha, S.; Mahalakshmi, R.; Raman, N.

    A series of Cu(II), Ni(II) and Zn(II) complexes of the type ML have been synthesized with Schiff bases derived from o-acetoacetotoluidide, 2-hydroxybenzaldehyde and o-phenylenediamine/1,4-diaminobutane. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMSO indicate that the complexes are non-electrolytic in nature. All the six metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic data. The analytical data helped to elucidate the structure of the metal complexes. The Schiff bases are found to act as tetradentate ligands using N2O2 donor set of atoms leading to a square-planar geometry for the complexes around all the metal ions. The binding properties of metal complexes with DNA were investigated by absorption spectra, viscosity measurements and cyclic voltammetry. Detailed analysis reveals that the metal complexes intercalate into the DNA base stack as intercalators. All the metal complexes cleave the pUC19 DNA in presence of H2O2. The Schiff bases and their complexes have been screened for their antibacterial activity against five bacterial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis, Klebsiella pneumoniae) by disk diffusion method. All the metal complexes have potent biocidal activity than the free ligands.

  17. Activation of CH Bonds via the Merger of Photoredox and Organocatalysis: A Coupling of Benzylic Ethers with Schiff Bases

    PubMed Central

    2015-01-01

    The photoredox-mediated coupling of benzylic ethers with Schiff bases has been accomplished. Direct benzylic CH activation by a combination of a thiol catalyst with an iridium photocatalyst and subsequent radicalradical coupling with secondary aldimines affords a variety of ?-amino ether products in good to excellent yields. Mechanistic studies suggest that a reductive quenching pathway of the photocatalyst is operable. PMID:25457231

  18. Design, spectral characterization, DFT and biological studies of transition metal complexes of Schiff base derived from 2-aminobenzamide, pyrrole and furan aldehyde

    NASA Astrophysics Data System (ADS)

    Tyagi, Prateek; Chandra, Sulekh; Saraswat, B. S.; Sharma, Deepansh

    2015-05-01

    A series of two biologically active Schiff base ligands L1, L2 have been synthesized in equimolar reaction of 2-aminobenzamide with pyrrol-2-carboxaldehyde and furan-2-carboxaldehyde. The synthesized Schiff bases were used for complexation with different metal ions like Co(II), Ni(II) and Cu(II) by using a molar ratio of ligand: metal as 2:1. The characterization of newly formed complexes was done by 1H NMR, UV-Vis, TGA, IR, mass spectrophotometry, EPR and molar conductivity studies. The thermal studies suggested that the complexes are more stable as compared to ligand. In DFT studies the geometries of Schiff bases and metal complexes were fully optimized with respect to the energy using the 6-31+g(d,p) basis set. On the basis of the spectral studies an octahedral geometry has been assigned for Co(II) and Ni(II) complexes and distorted octahedral geometry for Cu(II) complexes. All the synthesized compounds, were studied for their in vitro antimicrobial activities, against four bacterial strains and two fungal strains by using serial dilution method. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination.

  19. Synthesis, characterization and biological approach of metal chelates of some first row transition metal ions with halogenated bidentate coumarin Schiff bases containing N and O donor atoms.

    PubMed

    Prabhakara, Chetan T; Patil, Sangamesh A; Toragalmath, Shivakumar S; Kinnal, Shivashankar M; Badami, Prema S

    2016-04-01

    The impregnation of halogen atoms in a molecule is an emerging trend in pharmaceutical chemistry. The presence of halogens (Cl, Br, I and F) increases the lipophilic nature of molecule and improves the penetration of lipid membrane. The presence of electronegative halogen atoms increases the bio- activity of core moiety. In the present study, Co(II), Ni(II) and Cu(II) complexes are synthesised using Schiff bases (HL(I) and HL(II)), derived from 8-formyl-7-hydroxy-4-methylcoumarin/3-chloro-8-formyl-7-hydroxy-4-methylcoumarin with 2,4-difluoroaniline/o-toluidine respectively. The synthesized compounds were characterized by spectral (IR, NMR, UV-visible, Mass, ESI-MS, ESR), thermal, fluorescence and molar conductivity studies. All the synthesized metal complexes are completely soluble in DMF and DMSO. The non-electrolytic nature of the metal complexes was confirmed by molar conductance studies. Elemental analysis study suggest [ML2(H2O)2] stoichiometry, here M=Co(II), Ni(II) and Cu(II), L=deprotonated ligand. The obtained IR data supports the binding of metal ion to Schiff base. Thermal study suggests the presence of coordinated water molecules. Electronic spectral results reveal six coordinated geometry for the synthesized metal complexes. The Schiff bases and their metal complexes were evaluated for antibacterial (Pseudomonas aureginosa and Proteus mirabilis), antifungal (Aspergillus niger and Rhizopus oryzae), anthelmintic (Pheretima posthuma) and DNA cleavage (Calf Thymus DNA) activities. PMID:26874303

  20. Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: Synthesis, characterization, properties and biological activity

    NASA Astrophysics Data System (ADS)

    Keskio?lu, Eren; Gndzalp, Ayla Balaban; ete, Servet; Hamurcu, Fatma; Erk, Birgl

    2008-08-01

    A series of metal complexes were synthesized from equimolar amounts of Schiff bases: 1,4-bis[3-(2-hydroxy-1-naphthaldimine)propyl]piperazine (bappnaf) and 1,8-bis[3-(2-hydroxy-1-naphthaldimine)- p-menthane (damnaf) with metal chlorides. All of synthesized compounds were characterized by elemental analyses, spectral (UV-vis, IR, 1H- 13C NMR, LC-MS) and thermal (TGA-DTA) methods, magnetic and conductance measurements. Schiff base complexes supposed in tetragonal geometry have the general formula [M(bappnaf or damnaf)]Cl nH 2O, where M = Cr(III), Co(III) and n = 2, 3. But also Fe(III) complexes have octahedral geometry by the coordination of two water molecules and the formula is [Fe(bappnaf or damnaf)(H 2O) 2]Cl. The changes in the selected vibration bands in FT-IR indicate that Schiff bases behave as (ONNO) tetradentate ligands and coordinate to metal ions from two phenolic oxygen atoms and two azomethine nitrogen atoms. Conductance measurements suggest 1:1 electrolytic nature of the metal complexes. The synthesized compounds except bappnaf ligand have the antimicrobial activity against the bacteria: Escherichia coli (ATCC 11230), Yersinia enterocolitica (ATCC 1501), Bacillus magaterium (RSKK 5117), Bacillus subtilis (RSKK 244), Bacillus cereus (RSKK 863) and the fungi: Candida albicans (ATCC 10239). These results have been considerably interest in piperazine derivatives due to their significant applications in antimicrobial studies.

  1. Synthesis, Characterization, Antimicrobial, DNA Cleavage, and In Vitro Cytotoxic Studies of Some Metal Complexes of Schiff Base Ligand Derived from Thiazole and Quinoline Moiety

    PubMed Central

    Yernale, Nagesh Gunvanthrao; Bennikallu Hire Mathada, Mruthyunjayaswamy

    2014-01-01

    A novel Schiff base ligand N-(4-phenylthiazol-2yl)-2-((2-thiaxo-1,2-dihydroquinolin-3-yl)methylene)hydrazinecarboxamide (L) obtained by the condensation of N-(4-phenylthiazol-2-yl)hydrazinecarboxamide with 2-thioxo-1,2-dihydroquinoline-3-carbaldehyde and its newly synthesized Cu(II), Co(II), Ni(II), and Zn(II) complexes have been characterized by elemental analysis and various spectral studies like FT-IR, 1H NMR, ESI mass, UV-Visible, ESR, TGA/DTA, and powder X-ray diffraction studies. The Schiff base ligand (L) behaves as tridentate ONS donor and forms the complexes of type [ML(Cl)2] with square pyramidal geometry. The Schiff base ligand (L) and its metal complexes have been screened in vitro for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage activity of ligand and its metal complexes were studied using plasmid DNA pBR322 as a target molecule by gel electrophoresis method. The brine shrimp bioassay was also carried out to study the in vitro cytotoxicity properties for the ligand and its metal complexes against Artemia salina. The results showed that the biological activities of the ligand were found to be increased on complexation. PMID:24729778

  2. Synthesis and characterization of an azo dibenzoic acid Schiff base and its Ni(II), Pb(II), Zn(II) and Cd(II) complexes.

    PubMed

    Kakanejadifard, Ali; Esna-ashari, Fatemeh; Hashemi, Payman; Zabardasti, Abedin

    2013-04-01

    The new Schiff base 4,4'-(1E,1'E)-(3,3'-(1E,1'E)-(pyridine-2,6-diylbis(azan-1-yl-1-ylid ene))bis(methan-1-yl-1-ylidene)bis(4-hydroxy-3,1-phenylene))bis(diazene-2,1-diyl)dibenzoic acid (1) was prepared from the condensation reaction of 2,6-diaminopyridine with 4-((3-formyl-4-hydroxyphenyl)diazenyl)benzoic acid in methanol. The compound 1 is potentially an N, O multidentate chelating ligand which could form stable complexes with metal ions in 1:1 up to 1:3mol ratio of metal to ligand. The 1:1 complexes of Schiff base 1 with Ni(II), Pb(II), Zn(II) and Cd(II) have been synthesized by its condensation reaction with appropriate salts of metal ions. Structures of Schiff base (1) as well as its complexes with abovementioned metal ions were characterized by elemental analysis, mass, IR, UV-vis., (1)H and (13)? NMR spectroscopy. PMID:23376263

  3. Newer mixed ligand Schiff base complexes from aquo-N-(2?-hydroxy acetophenone) glycinatocopper(II) as synthon: DFT, antimicrobial activity and molecular docking study

    NASA Astrophysics Data System (ADS)

    Pramanik, Harun A. R.; Das, Dharitri; Paul, Pradip C.; Mondal, Paritosh; Bhattacharjee, Chira R.

    2014-02-01

    Synthesis of a series of newer mixed ligand copper(II) complexes of aminoacid Schiff base of the type [CuL(X)] (L = N-(2?-hydroxy acetophenone) glycinate, X = imidazole (im) 2, benzimidazole (benz) 3, pyridine (py) 4, hydrazine (hz) 5,8-hydroxyquinoline (8-hq) 6, pyrrolidine (pyrr) 7, piperidine (pip) 8, and nicotinamide (nic) 9) have been accomplished from the interaction of an aquated Schiff base complex, [CuL(H2O)]H2O, 1 with some selected neutral nitrogen-donor ligands. The copper(II) Schiff base complex, [CuL(H2O)]H2O, L = N-(2?-hydroxy acetophenone) glycinate was synthesized from the reaction of glycine and 2? hydroxy acetophenone and copper(II) acetate. The compounds were characterised by elemental analysis, spectral, magnetic and thermal studies. The density functional theory calculations were performed using LANL2DZ and 6-311 G(d, p) basis sets with B3LYP correlation functional to ascertain the stable electronic structure, HOMO-LUMO energy gap, chemical hardness and dipole moment of the mixed ligand complexes. A distorted square planar geometry has been conjectured for the complexes. Antibacterial activities of the ligand and its metal complexes have been tested against selected gram-positive and gram-negative strains and correlated with computational docking scores.

  4. Synthesis and Fluorescence Properties of Novel indol-3yl-thiazolo[3,2-a][1,3,5]triazines and indole-3-carbaldehyde Schiff Bases.

    PubMed

    Sravanthi, T V; Manju, S L

    2015-11-01

    Novel photoactive 4-(4-chlorophenyl)-2-(1H-indol-3-yl)-6-substituted phenyl-2H-thiazolo[3,2-a][1,3,5]triazines were synthesized by the conjugate addition of ammonia to the indole-3-carbaldehyde Schiff bases followed by the condensation with 4-chlorobenzaldehyde. All the synthesized compounds were characterized by FT-IR, NMR, mass spectra and elemental analyses. Their antioxidant property, electrochemical and photophysical properties in different organic solvents were investigated. Comparative discussion on the photophysical properties of indole-3-carbaldehyde Schiff bases and 4-(4-chlorophenyl)-2-(1H-indol-3-yl)-6-substituted phenyl-2H-thiazolo[3,2-a][1,3,5]triazines has been described. The fluorescence quantum yield of Schiff bases (?f?=?0.66-0.70 in DMSO) found to be interestingly higher. High fluorescence quantum yield, large molar extinction coefficient, high stokes shift and smaller optical band gap positioning these new derivatives as an efficient metal free organic fluorescent and semiconductor material. Graphical Abstract ?. PMID:26432553

  5. Antimicrobial activity and spectral, magnetic and thermal studies of some transition metal complexes of a Schiff base hydrazone containing a quinoline moiety.

    PubMed

    Al-Sha'alan, Nora H

    2007-01-01

    A series of new copper(II), cobalt(II), nickel(II), manganese(II), iron(III), and uranyl(VI) complexes of the Schiff base hydrazone 7-chloro-4-(benzylidene-hydrazo)quinoline (HL) were prepared and characterized. The Schiff base behaves as a monobasic bidentate ligand. Mononuclear complexes with the general composition [ML2(Cl)m(H2O)2(OEt)n] x xEtOH (M = Cu(II), Co(II), Ni(II), Mn(II), Fe(III) or UO2(VI); m and n = 0-1; x = 1-3) were obtained in the presence of Li(OH) as a deprotonating agent. The nature of bonding and the stereochemistry of the complexes have been deduced from elemental analyses, infrared, electronic spectra, magnetic susceptibility and conductivity measurements. An octahedral geometry was suggested for all the complexes except the Cu(II) and UO2(VI) ones. The Cu(II) complex has a square-planar geometry distorted towards tetrahedral, while the UO2(VI) complex displays its favored heptacoordination. The Schiff base ligand, HL, and its complexes were tested against one strain gram +ve bacteria (Staphylococcus aureus), gram -ve bacteria (Escherichia coli), and Fungi (Candida albicans). The prepared metal complexes exhibited higher antibacterial activities than the parent ligand and their biopotency is discussed. PMID:17873842

  6. Synthesis and biological evaluation of novel 6-hydroxy-benzo[d][1,3]oxathiol-2-one Schiff bases as potential anticancer agents.

    PubMed

    Chazin, Eliza de Lucas; Sanches, Paola de Souza; Lindgren, Eric Brazil; Vellasco Jnior, Walcimar Trindade; Pinto, Laine Celestino; Burbano, Rommel Mario Rodrguez; Yoneda, Julliane Diniz; Leal, Ktia Zaccur; Gomes, Claudia Regina Brando; Wardell, James Lewis; Wardell, Solange Maria Silva Veloso; Montenegro, Raquel Carvalho; Vasconcelos, Thatyana Rocha Alves

    2015-01-01

    With the aim of discovering new anticancer agents, we have designed and synthesized novel 6-hydroxy-benzo[d][1,3]oxathiol-2-one Schiff bases. The synthesis started with the selective nitration at 5-position of 6-hydroxybenzo[d][1,3]oxathiol-2-one (1) leading to the nitro derivative 2. The nitro group of 2 was reduced to give the amino intermediate 3. Schiff bases 4a-r were obtained from coupling reactions between 3 and various benzaldehydes and heteroaromatic aldehydes. All the new compounds were fully identified and characterized by NMR (1H and 13C) and specifically for 4q by X-ray crystallography. The in vitro cytotoxicity of the compounds was evaluated against cancer cell lines (ACP-03, SKMEL-19 and HCT-116) by using MTT assay. Schiff bases 4b and 4o exhibited promising cytotoxicity against ACP-03 and SKMEL-19, respectively, with IC50 values lower than 5 ?M. This class of compounds can be considered as a good starting point for the development of new lead molecules in the fight against cancer. PMID:25633329

  7. Synthesis and evaluation of a nanoglobular dendrimer 5-aminosalicylic acid conjugate with a hydrolyzable Schiff base spacer for treating retinal degeneration

    PubMed Central

    Wu, Xueming; Yu, Guanping; Luo, Chengcai; Maeda, Akiko; Zhang, Ning; Sun, Da; Zhou, Zhuxian; Puntel, Anthony; Palczewski, Krzysztof; Lu, Zheng-Rong

    2014-01-01

    Biocompatible dendrimers with well-defined nanosizes are increasingly being used as carriers for drug delivery. 5-Aminosalicylic acid (5-ASA) is an FDA approved therapeutic agent recently found effective in treating retinal degeneration of animal models. Here, a water-soluble dendrimer conjugate of 5-ASA (AGFB-ASA) was designed to treat such retinal degeneration. The drug was conjugated to a generation 2 (G2) lysine dendrimer with a silsesquioxane core (nanoglobule) by using a hydrolysable Schiff base spacer. Incubation of nanoglobular G2 dendrimer conjugates containing a 4-formylbenzoate (FB) Schiff base spacer in pH 7.4 phosphate buffers at 37 C gradually released 5-ASA. Drug release from the dendrimer conjugate was significantly slower than from the low molecular weight free Schiff base of 5-ASA (FB-ASA). 5-ASA release from the dendrimer conjugate was dependent on steric hindrance around the spacer. After intraperitoneal injection, the nanoglobular 5-ASA conjugate provided more effective 7-day protection against light-induced retinal degeneration at a reduced dose than free 5-ASA in Abca4?/?Rdh8?/? mice. The dendrimer 5-ASA conjugate with a degradable spacer could be a good candidate for controlled delivery of 5-ASA to the eye for treatment of retinal degeneration. PMID:24350906

  8. Synthesis, spectral characterization, catalytic and antibacterial studies of new Ru(III) Schiff base complexes containing chloride/bromide and triphenylphosphine/arsine as co-ligands

    NASA Astrophysics Data System (ADS)

    Arunachalam, S.; Padma Priya, N.; Jayabalakrishnan, C.; Chinnusamy, V.

    2009-10-01

    A new Ru(III) Schiff base complexes of the type [RuX(EPh 3)L] (X = Cl/Br; E = P/As; L = dianion of the Schiff bases were derived by the condensation of 1,4-diformylbenzene with o-aminobenzoic acid/ o-aminophenol/ o-aminothiophenol in the 1:2 stoichiometric ratio) have been synthesized from the reactions of [RuX 3(EPh 3) 3] with appropriate Schiff base ligands in benzene in the 2:1 stoichiometric ratio. The new complexes have been characterized by analytical, spectral (IR, electronic, 1H, 13C NMR and ESR), magnetic moment and electrochemical studies. An octahedral structure has been tentatively proposed for all these new complexes. All the new complexes have been found to be better catalyst for the oxidation of alcohols using molecular oxygen as co-oxidant at ambient temperature and aryl-aryl coupling reactions. These complexes were also subjected to antibacterial activity studies against Escherichia coli, Aeromonas hydrophilla and Salmonella typhi.

  9. Synthesis and characterization of an azo dibenzoic acid Schiff base and its Ni(II), Pb(II), Zn(II) and Cd(II) complexes

    NASA Astrophysics Data System (ADS)

    Kakanejadifard, Ali; Esna-ashari, Fatemeh; Hashemi, Payman; Zabardasti, Abedin

    2013-04-01

    The new Schiff base 4,4'-(1E,1'E)-(3,3'-(1E,1'E)-(pyridine-2,6-diylbis(azan-1-yl-1-ylid ene))bis(methan-1-yl-1-ylidene)bis(4-hydroxy-3,1-phenylene))bis(diazene-2,1-diyl)dibenzoic acid (1) was prepared from the condensation reaction of 2,6-diaminopyridine with 4-((3-formyl-4-hydroxyphenyl)diazenyl)benzoic acid in methanol. The compound 1 is potentially an N, O multidentate chelating ligand which could form stable complexes with metal ions in 1:1 up to 1:3 mol ratio of metal to ligand. The 1:1 complexes of Schiff base 1 with Ni(II), Pb(II), Zn(II) and Cd(II) have been synthesized by its condensation reaction with appropriate salts of metal ions. Structures of Schiff base (1) as well as its complexes with abovementioned metal ions were characterized by elemental analysis, mass, IR, UV-vis., 1H and 13С NMR spectroscopy.

  10. Synthesis, spectral characterization and DNA binding of Schiff-base metal complexes derived from 2-amino-3-hydroxyprobanoic acid and acetylacetone

    NASA Astrophysics Data System (ADS)

    Hosny, Nasser Mohammed; Hussien, Mostafa A.; Radwan, Fatima M.; Nawar, Nagwa

    2014-11-01

    Four new metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H3L) resulted from the condensation of the amino acid 2-amino-3-hydroxyprobanoic acid (serine) and acetylacetone have been synthesized and characterized by, elemental analyses, ES-MS, IR, UV-Vis., 1H NMR, 13C NMR, ESR, thermal analyses (TGA and DTG) and magnetic measurements. The results showed that the Schiff-base ligand acts as bi-negative tridentate through the azomethine nitrogen, the deprotonated carboxylate oxygen and the enolic carbonyl oxygen. The optical band gaps measurements indicated the semi-conducting nature of these complexes. Molecular docking was used to predict the binding between the Schiff base ligand with the receptor of prostate cancer mutant H874Y. The interactions between the Cu(II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA in an intercalative mode.

  11. Design, spectral characterization, DFT and biological studies of transition metal complexes of Schiff base derived from 2-aminobenzamide, pyrrole and furan aldehyde.

    PubMed

    Tyagi, Prateek; Chandra, Sulekh; Saraswat, B S; Sharma, Deepansh

    2015-05-15

    A series of two biologically active Schiff base ligands L(1), L(2) have been synthesized in equimolar reaction of 2-aminobenzamide with pyrrol-2-carboxaldehyde and furan-2-carboxaldehyde. The synthesized Schiff bases were used for complexation with different metal ions like Co(II), Ni(II) and Cu(II) by using a molar ratio of ligand: metal as 2:1. The characterization of newly formed complexes was done by (1)H NMR, UV-Vis, TGA, IR, mass spectrophotometry, EPR and molar conductivity studies. The thermal studies suggested that the complexes are more stable as compared to ligand. In DFT studies the geometries of Schiff bases and metal complexes were fully optimized with respect to the energy using the 6-31+g(d,p) basis set. On the basis of the spectral studies an octahedral geometry has been assigned for Co(II) and Ni(II) complexes and distorted octahedral geometry for Cu(II) complexes. All the synthesized compounds, were studied for their in vitro antimicrobial activities, against four bacterial strains and two fungal strains by using serial dilution method. The data also revealed that the metal complexes showed better activity than the ligands due to chelation/coordination. PMID:25706679

  12. Enantioselectivity in Ni(II) Schiff-base complexes derived from amino-acids and (S)-o-N-(N-benzylprolyl)aminobenzophenone: molecular structure of several chiral Ni(II) Schiff-base complexes, circular dichroism and molecular mechanics studies.

    PubMed

    Pessoa, J Costa; Correia, I; Galvo, A; Gameiro, A; Felix, V; Fiuza, E

    2005-07-01

    Several Ni(II) complexes derived from (S)-o-N-(N-benzylprolyl)aminobenzophenone ((S)-BBP) and amino acids of general formula [Ni((S)-BBP-L-(or D-)-aa)] were prepared. The crystal and molecular structures of [Ni((S)-BBP-Gly)], [Ni((S)-BBP-L-Ser)] and [Ni((S)-BBP-L-aaIm)](aaIm =L-2-amino-3-(imidazol-1-yl)propanoate were determined by X-ray diffraction analysis. In the three complexes the nickel atoms display a square-planar coordination and the overall structure around the metal indicates that the entire Schiff-base ligands form quite rigid frameworks. Molecular mechanics calculations were carried out for complexes [Ni((S)-BBP-Gly)], [Ni((S)-BBP-Ser)] and [Ni((S)-BBP-aaIm)] containing either the L- or D-amino acid forms, and the factors controlling the stereoselectivity are discussed. Several other [Ni((S)-BBP-L-aa)] complexes are also prepared and their circular dichroism spectra in solution and of the solids dispersed in KBr disks are measured and discussed. In agreement with other studies in solution with similar [Ni((S)-BBP-aa)] complexes, the Cotton effects for the bands with lambda(max) at 520--530 nm are positive when the amino acids have the L-configuration at the alpha-carbon. The same is observed in this work for the solid-state CD spectra of all compounds. PMID:15962053

  13. Surface tectonics of nanoporous networks of melamine-capped molecular building blocks formed through interface Schiff-base reactions.

    PubMed

    Liu, Xuan-He; Wang, Dong; Wan, Li-Jun

    2013-10-01

    Control over the assembly of molecules on a surface is of great importance for the fabrication of molecule-based miniature devices. Melamine (MA) and molecules with terminal MA units are promising candidates for supramolecular interfacial packing patterning, owing to their multiple hydrogen-bonding sites. Herein, we report the formation of self-assembled structures of MA-capped molecules through a simple on-surface synthetic route. MA terminal groups were successfully fabricated onto rigid molecular cores with 2-fold and 3-fold symmetry through interfacial Schiff-base reactions between MA and aldehyde groups. Sub-molecular scanning tunneling microscopy (STM) imaging of the resultant adlayer revealed the formation of nanoporous networks. Detailed structural analysis indicated that strong hydrogen-bonding interactions between the MA groups persistently drove the formation of nanoporous networks. Herein, we demonstrate that functional groups with strong hydrogen-bond-formation ability are promising building blocks for the guided assembly of nanoporous networks and other hierarchical 2D assemblies. PMID:23868669

  14. Solvent-assistant self-assembly of an AIE+TICT fluorescent Schiff base for the improved ammonia detection.

    PubMed

    Han, Tianyu; Wei, Wei; Yuan, Jing; Duan, Yuai; Li, Yaping; Hu, Liangyu; Dong, Yuping

    2016-04-01

    Solvent-assistant self-assembly of an AIE+TICT fluorescent Schiff base into one-dimensional nanofilaments has been developed. The orientation of the assemblies can be controlled by a simple dewetting process: the filaments are interweaved when the self-assembly process is performed on a horizontal substrate, while tilting the substrate to a tiny angle results in the formation of highly oriented ones with long-range order as verified by microscopic examination. The compound shows remarkable fluorescent response to ammonia gas based on a TICT-LE transition. The self-assembled film presents higher detection sensitivity compared with the non-assembled test paper: the former enables 4.75 times faster response time and 6.86 times lower detection limit than the latter. Furthermore, the former demonstrates better selectivity toward ammonia gas in the presence of various organic amines. The sensing devices also enjoy the advantage of cyclic utilization. The fluorescence of the fumed devices can be converted back into the original state when they are heated at 100°C for 5min, as thermal treatment can desorb the ammonia gas that adsorbed in the sensing devices. PMID:26838387

  15. Novel rhenium(III, IV, and V) tetradentate N2O2 Schiff base mononuclear and dinuclear complexes.

    PubMed

    Rotsch, David A; Reinig, Kimberly M; Weis, Eric M; Taylor, Anna B; Barnes, Charles L; Jurisson, Silvia S

    2013-08-28

    Reaction of (Bu4N)[ReOCl4] with the tetradentate Schiff base ligand ?,?'-[(1,1-dimethylethylene)dinitrilo]di-o-cresol (sal2ibnH2) yields cis-[Re(V)OCl(sal2ibn)], which quickly forms trans-[?-O(Re(V)O(sal2ibn))2] in solution. The dinuclear complex can also be isolated by the addition of base (Et3N) to the reaction mixture. Conversely, the mononuclear complex can be trapped as cis-[Re(V)O(NCS)(sal2ibn)] by addition of (Bu4N)SCN to the reaction mixture. Reduction of cis-[Re(V)O(NCS)sal2ibn] with triphenylphosphine gives the rare trans-[Re(III)(NCS)(PPh3)(sal2ibn)] and unique ?-oxo Re(IV) dimer trans-[?-O(Re(IV)(NCS)(sal2ibn))2]. All of the complexes were characterized by (1)H and (13)C NMR, FT-IR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), cyclic voltammetry and single crystal X-ray diffraction. PMID:23824208

  16. Novel Rhenium(III, IV, and V) Tetradentate N2O2 Schiff Base Mononuclear and Dinuclear Complexes

    PubMed Central

    Rotsch, David A.; Reinig, Kimberly M.; Weis, Eric M.; Taylor, Anna B.; Barnes, Charles L.

    2013-01-01

    Reaction of (Bu4N)[ReOCl4] with the tetradentate Schiff base ligand ?, ?-[(1,1-dimethylethylene)dinitrilo]di-o-cresol (sal2ibnH2) yields cis-[ReVOCl(sal2ibn)], which quickly forms trans-[?-O(ReVO(sal2ibn))2] in solution. The dinuclear complex can also be isolated by the addition of base (Et3N) to the reaction mixture. Conversely, the mononuclear complex can be trapped as cis-[ReVO(NCS)(sal2ibn)] by addition of (Bu4N)SCN to the reaction mixture. Reduction of cis-[ReVO(NCS)sal2ibn] with triphenylphosphine gives the unique trans-[ReIII(NCS)(PPh3)(sal2ibn)] and rare ?-oxo Re(IV) dimer trans-[?-O(ReIV(NCS)(sal2ibn))2]. All of the complexes were characterized by 1H and 13C NMR, FT-IR spectroscopy, electrospray ionization mass spectrometry (ESI-MS), cyclic voltammetry and single crystal X-ray diffraction. PMID:23824208

  17. Phase transition and vapochromism in molecular assemblies of a polymorphic zinc(II) Schiff-base complex.

    PubMed

    Oliveri, Ivan Pietro; Malandrino, Graziella; Di Bella, Santo

    2014-09-15

    This paper reports for the first time the irreversible thermally induced phase transition, accompanied by color change, and the vapochromic behavior of an amphiphilic, Lewis acidic Zn(II) Schiff-base complex, through detailed X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry, and optical absorption studies. The unprecedented irreversible phase transition for such kind of complexes is associated with a thermal, lamellar-to-hexagonal columnar structural transition, which involves a different arrangement of each molecular unit within the assembled structure, H- and J-type aggregates, respectively, responsible for the thermochromic behavior. The vapochromism, investigated either in powder samples or in thermally annealed cast films, is related to the formation of 1:1 adducts upon exposure to vapors of strong Lewis bases and implies dramatic optical absorption variations and naked-eye observation of the change in color from red-brown to red. The chemisorption process is fast, completely reversible, reproducible, and selective for amines. The reversible switching of the chemisorption-desorption process in cast films is demonstrated by successive cycles, amine exposure and subsequent heating, by monitoring the substantial optical absorption changes in the visible region. Vapochromism of this material can potentially be used to detect vapors of volatile amines. PMID:25148651

  18. Synthesis, spectral characterization and DNA bindings of tridentate N2O donor Schiff base metal(II) complexes.

    PubMed

    Kathiresan, Sellamuthu; Anand, Thangavel; Mugesh, Subramanian; Annaraj, Jamespandi

    2015-07-01

    To evaluate the biological preference of synthetic small drugs towards DNA target, new metal based chemotherapeutic agents of Cu(II), Co(II), Ni(II) and Zn(II), 2,4-diiodo-6-((pyridin-2-ylmethylimino)methyl)phenol (L) Schiff base complexes (1, 2, 3 &4) having N,N,O donor system respectively were synthesized and thoroughly characterized. The IR results confirmed the tridentate binding of the ligand with metal centre during complexation and reflects the proposed structure. The density function theory calculations were also used to further investigate the electronic structure and properties of ligand and complexes. The preliminary investigation of herring Sperm (HS-DNA) interaction propensity of complexes 1-4 were carried out in Tris-HCl buffer at pH 7.1 to demonstrate their mode of interactions. The obtained results reveal that these complexes significantly interact with DNA on the grooves, further, this observed mode of interactions was also confirmed by molecular docking evaluations. The complexes 1-4 were also screened for antimicrobial evaluations which demonstrated that their significant activity against various human pathogens. The cleavage studies with pBR322 plasmid DNA revealed higher nuclease activity of 1 as compared to other complexes. PMID:26000741

  19. New ruthenium(II) carbonyl complexes bearing disulfide Schiff base ligands and their applications as catalyst for some organic transformations

    NASA Astrophysics Data System (ADS)

    Prakash, Govindan; Viswanathamurthi, Periasamy

    2014-08-01

    Schiff base disulfide ligands (H2L1-6) were synthesized from the condensation of cystamine with salicylaldehyde(H2L1), 5-chlorosalicylaldehyde(H2L2), o-vanillin(H2L3), 2-hydroxyacetophenone(H2L4), 3-methyl-2-hydroxyacetophenone(H2L5), and 2-hydroxy-1-naphthaldehyde(H2L6). H2L1-6 reacts with the ruthenium precursor complex [RuHCl(CO)(PPh3)3] in benzene giving rise to six new ruthenium(II) complexes of general formula [Ru(CO)L1-6]. Characterization of the new complexes was carried out by using elemental and spectral (IR, UV-Vis, NMR (1H and 13C) and Mass) techniques. An octahedral geometry was assigned for all the complexes based on the spectral data obtained. The catalytic efficiency of the new complexes in aldehyde to amide conversion in the presence of NaHCO3, N-alkylation of aniline in the presence of t-BuOK, and transfer hydrogenation of ketones in the presence of iPrOH/KOH reactions were studied. Furthermore, the effect of solvents and catalyst/substrate ratio on the catalytic aldehyde to amide conversion were also discussed.

  20. Triaryl-Substituted Schiff Bases Are High-Affinity Subtype-Selective Ligands for the Estrogen Receptor

    PubMed Central

    2015-01-01

    We have explored the isoelectronic replacement of the C=C double bond found at the core of many nonsteroidal estrogen ligands with a simple Schiff base (C=N). Di- and triaryl-substituted imine derivatives were conveniently prepared by the condensation of benzophenones with various anilines without the need for phenolic hydroxy protection. Most of these imines demonstrated high affinity for the estrogen receptors, which, in some cases exceeded that of estradiol. In cell-based assays, these imines profiled as ERα agonists but as ERβ antagonists, showing preferential reliance on the N-terminal activation function (AF1), which is more active in ERα. X-ray analysis revealed that the triaryl-imines distort the ligand-binding pocket in a new way: by controlling the separation of helices 3 and 11, which appears to alter the C-terminal AF2 surface that binds transcriptional coactivators. This work suggests that C=N for C=C substitution might be more widely considered as a general strategy for preparing drug analogues. PMID:24708493

  1. New ruthenium(II) carbonyl complexes bearing disulfide Schiff base ligands and their applications as catalyst for some organic transformations.

    PubMed

    Prakash, Govindan; Viswanathamurthi, Periasamy

    2014-08-14

    Schiff base disulfide ligands (H2L(1-6)) were synthesized from the condensation of cystamine with salicylaldehyde(H2L(1)), 5-chlorosalicylaldehyde(H2L(2)), o-vanillin(H2L(3)), 2-hydroxyacetophenone(H2L(4)), 3-methyl-2-hydroxyacetophenone(H2L(5)), and 2-hydroxy-1-naphthaldehyde(H2L(6)). H2L(1-6) reacts with the ruthenium precursor complex [RuHCl(CO)(PPh3)3] in benzene giving rise to six new ruthenium(II) complexes of general formula [Ru(CO)L(1-6)]. Characterization of the new complexes was carried out by using elemental and spectral (IR, UV-Vis, NMR ((1)H and (13)C) and Mass) techniques. An octahedral geometry was assigned for all the complexes based on the spectral data obtained. The catalytic efficiency of the new complexes in aldehyde to amide conversion in the presence of NaHCO3, N-alkylation of aniline in the presence of t-BuOK, and transfer hydrogenation of ketones in the presence of iPrOH/KOH reactions were studied. Furthermore, the effect of solvents and catalyst/substrate ratio on the catalytic aldehyde to amide conversion were also discussed. PMID:24747860

  2. Synthesis, spectroscopic (electronic, IR, NMR and ESR) and theoretical studies of transition metal complexes with some unsymmetrical Schiff bases

    NASA Astrophysics Data System (ADS)

    Singh, Vinod P.; Singh, Shweta; Singh, Divya P.; Tiwari, K.; Mishra, Monika

    2014-01-01

    Two unsymmetrical Schiff bases, glyoxal salicylaldehyde oxalic acid dihydrazone (gsodh) and glyoxal salicylaldehyde malonic acid dihydrazone (gsmdh) and their Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized. The structures of metal complexes are elucidated on the basis of elemental analyses, molar conductance, magnetic susceptibility measurements, electronic, ESR, IR and NMR (1H and 13C) spectral studies. Both ligands show monobasic tetra-dentate behaviour, bonding through CO, two CN and a phenolate group. The electronic spectral studies in solid state indicate a square planar geometry for Ni(II) and Cu(II) complexes and a tetrahedral geometry for Co(II) complexes. However, Co(II) and Cu(II) complexes adopt octahedral geometry in DMSO solution. The ESR spectra of Cu(II) complexes in DMSO solution at 77 K predict an elongated tetragonal distorted octahedral geometry around metal ion and presence of unpaired electron in d orbital. Further, the structures of ligands and their Ni(II) complexes have been satisfactorily modelled by calculations based on density functional theory (DFT). The electronic spectra of Ni(II) complexes are also analyzed in depth with the help of time dependent-DFT (TD-DFT). The theoretical analyses of electronic structure and molecular orbitals have demonstrated that the high-energy absorption bands are M ? L charge transfer and low energy transitions are d-d transitions.

  3. Study of the interaction between a new Schiff-base complex and bovine serum albumin by fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Xiang, Yanling; Wu, Fangying

    2010-10-01

    A new Schiff-base compound, N'-(2-hydroxynaphthalenemethylene)-4-(2-hydroxyl naphthalenemethylenamine)benzoylhydrazine ( 1), was synthesized and the interaction between zinc complex ( 1-Zn) and bovine serum albumin (BSA) was investigated by fluorescence and absorption spectroscopies. A marked increase in the fluorescence intensity of 1-Zn was observed at 475 nm upon addition of BSA when excitation wavelength was set at 370 nm in pH 7.4 Tris-HCl buffer solution. Reversely, the intrinsic fluorescence of BSA could be quenched by 1-Zn complex. The quenching mechanism was suggested as static quenching according to the Stern-Volmer equation and the UV-vis absorption spectral change of 1-Zn upon addition of BSA. The binding constants Kb and the number of binding sites n were calculated. The effect of 1-Zn on the conformation of BSA was studied using synchronous fluorescence spectroscopy and three-dimensional fluorescence spectroscopy. In addition, the binding average distance r between the donor (BSA) and acceptor ( 1-Zn) was estimated based on the Frster's non-radiation energy transfer theory.

  4. Pd(II) and Zn(II) Based Complexes with Schiff Base Ligands: Synthesis, Characterization, Luminescence, and Antibacterial and Catalytic Activities

    PubMed Central

    Feng, Zhi-Qiang; Yang, Xiao-Li; Ye, Yuan-Feng

    2013-01-01

    Two new metal complexes involving Schiff base ligands, namely, [Pd(L1)2] (1) and [Zn(L2)2] (2), [HL1: 2,4-dibromo-6-((E)-(mesitylimino)methyl)phenol and HL2: 2-((E)-(2,6-diisopropylphenylimino)methyl)-4,6-dibromophenol], have been solvothermally synthesized and characterized by elemental analysis, IR-spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Both 1 and 2 are mononuclear cyclometalated complexes with square planar and tetrahedral coordination geometry, respectively. 1 and 2 display photoluminescence in the solid state at 298?K (fluorescence lifetimes ? = 5.521??s at 508?nm for 1; ? = 3.697??s at 506?nm for 2). These Schiff base ligands and their metal complexes have been screened for antibacterial activity against several bacteria strains, and the results are compared with the activity of penicillin. Moreover, the Suzuki reaction of 4-bromoanisole with phenylboronic acid by 1 has also been studied. PMID:24307886

  5. Electroanalytical and naked eye determination of Cu(2+) ion in various environmental samples using 5-amino-1,3,4-thiadiazole-2-thiol based Schiff bases.

    PubMed

    Bandi, Koteswara Rao; Singh, Ashok Kumar; Upadhyay, Anjali

    2014-01-01

    Novel polydentate Schiff bases 4-(5-mercapto-1,3,4-thiadiazol-2-ylimino)pentan-2-one (S1) and (2-(indol-3-yl)vinyl)-1,3,4-thiadiazole-2-thiol (S2) were synthesized and explored as Cu(2+) selective polymeric membrane electrodes (PME) using different plasticizers and anionic excluders. The potentiometric data revealed that the PME having the membrane composition (S2: NaTPB: TBP: PVC as 4: 2: 58: 36 (w/w; mg)) is shown to have good results. Thus the coated graphite electrode (CGE) with the same composition as the best PME was also fabricated and investigated as Cu(2+) selective electrode. It was found that CGE showed better response characteristics than PME with respect to low detection limit (1.210(-8)molL(-1)), near Nernstian slope (29.80.4mV decade(-1) of activity), wide working concentration range (6.410(-8)-1.010(-1)molL(-1)), long shelf life (90days) and fast response time (9s). The CGE was used successfully as an indicator electrode for the potentiometric determination of Cu(2+) ion against EDTA and also used to quantify Cu(2+) ion in soil, water, medicinal plants, vegetables and edible oil samples. The Schiff base S2 is used as chemosensor for the selective determination of Cu(2+) ion. PMID:24268244

  6. Heterobinuclear Zn-Ln (Ln = La, Nd, Eu, Gd, Tb, Er and Yb) complexes based on asymmetric Schiff-base ligand: synthesis, characterization and photophysical properties.

    PubMed

    Zhao, Shunsheng; Liu, Xiangrong; Lü, Xingqiang; Wong, Wai-Kwok

    2013-01-01

    With a novel asymmetric Schiff-base zinc complex ZnL (H2 L = N-(3-methoxysalicylidene)-N'-(5-bromo-3-methoxysalicylidene)phenylene-1,2-diamine), obtained from phenylene-1,2-diamine, 3-methoxysalicylaldehyde and 5-bromo-3-methoxysalicylaldehyde, as the precursor, a series of heterobinuclear Zn-Ln complexes [ZnLnL(NO3 )3 (CH3 CN)] (Ln = La, 1; Ln = Nd, 2; Ln = Eu, 3; Ln = Gd, 4; Ln = Tb, 5; Ln = Er, 6; Ln = Yb, 7) were synthesized by the further reaction with Ln(NO3 )3 ·6H2 O, and characterized by Fourier transform-infrared, fast atom bombardment mass spectroscopy and elemental analysis. Photophysical studies of these complexes show that the strong and characteristic near-infrared luminescence of Nd(3+) , Yb(3+) and Er(3+) with emissive lifetimes in the microsecond range has been sensitized from the excited state of the asymmetric Schiff-base ligand due to effective intramolecular energy transfer; the other complexes do not show characteristic emission due to the energy gap between the chromophore and lanthanide ions. PMID:23001932

  7. Nad(P)H vs. Schiff base fluorescence by spectroscopy, imaging, and maximum sensitivity micrographs at the convergence of cellular detoxification, senescence, and transformation

    NASA Astrophysics Data System (ADS)

    Kohen, Elli; Hirschberg, Joseph G.; Kohen, Cahide; Monti, Marco

    1999-05-01

    Two intracellular fluorochromes, NAD(P)H and Schiff Bases, provide monitoring of energy metabolism and photoperoxidations. Fluorochrome spectra and topographic distribution are measured in a microspectrofluorometer, pixel by pixel using a CCD. The mitochondrial arrangement of Saccharomyces cerevisie and metabolic activity at nuclear kidney epithelial sites is revealed. A kind of accelerated photoaging results in the accumulation of Schiff pigment. Schiff base emission is red-shifted, and it may be preceded by photo-oxidation of NAD(P)H. UVA production of oxygen radicals and peroxides may influence detoxification, senescence and/or transformation. Besides lysosomes, mitochondrial energy metabolism and ER and Golgi detoxification are open to study as multi-organelle complexes with fluorescent xenobiotics and probes. Melanocytes vs. melanoma cells in culture will be investigated using a new compact interferometer for Fourier coding of both emission and excitation spectra. Surprisingly, the photographic method, using the highest sensitivity films, may sometimes produce excellent structural detail. However, for kinetic studies, the CCD, or equivalent, is required. There is good potential for applications in diagnostics and prognostics plus the evaluation of new biopharmeceuticals.

  8. Reductive defluorination of saturated fluorocarbons by organometallic reagents and aryl halide coordination to tungsten(II) and molybdenum(II) by chelating Schiff base ligands

    SciTech Connect

    Harrison, R.G.

    1993-01-01

    Strong organometallic nucleophiles cleave C-F bonds of fluorocarbons such as perfluorodecalin and perfluoro(methylcyclohexane) to afford complexes of the form Cp(CO)[sub 2]FeR, where R is a fluoro aromatic derivative of the perfluorocarbon, when NaCpFe(CO)[sub 2] is used as a nucleophile. Fluoride ion and [Cp(CO)[sub 2]Fe][sub 2] are also recovered in good yields. The reaction occurs at ambient temperature and reaction times vary from one to four hours depending on the substrate used. An electron transfer mechanism is proposed and radical character exists in the intermediates, as evident by hydrogen incorporation into the fluorocarbon products and rate enhancement when the reaction is run in the presence of a hydrogen radical donor. The reactivity patterns of model systems indicate hydrogen incorporation occurred early along the reaction pathway. NaRe(CO)[sub 5] and Ni(P(C[sub 2]H[sub 5])[sub 3])[sub 4] also show reactivity towards the perfluorosubstrates, but NaCpMo(CO)[sub 3] and Na[sub 2]Fe(CO)[sub 4] do not. Aryl-X (X = Cl, Br, I, OCH[sub 3]) groups coordinate to Mo(II) and W(II), through the lone pairs on the atoms, forming seven coordinate metal carbonyls, when chelating nitrogen Schiff base ligands are oxidatively added to W(CO)[sub 3](NCCH[sub 3])[sub 3] or Mo(CO)[sub 3](toluene) in THF. The major mode of reactivity of these coordination compounds is aryl halide dissociation. Competition with typical solvents as monitored by solution IR and ligand equilibrium studies give relative bond strengths. X-ray crystallography shows covalent bonding between the metal and aryl halide groups and the metal geometry is capped octahedral. The aryl halide complexes substitute CO preferentially over the aryl halide when exposed to phosphine donor ligands. Aryl-fluoride coordination was not detected, but halide bridged metal dimers were isolated instead.

  9. Synthesis, spectroscopic, thermal and electrical conductivity studies of three charge transfer complexes formed between 1,3-di[( E)-1-(2-hydroxyphenyl)methylideneamino]-2-propanol Schiff base and different acceptors

    NASA Astrophysics Data System (ADS)

    Refat, Moamen S.; Ibrahim, Mohamed M.; Moussa, Mohamed A. A.

    2012-01-01

    Charge-transfer complexes (CTC) resulting from interactions of 1,3-di[( E)-1-(2-hydroxyphenyl) methylideneamino]-2-propanol Schiff base with some acceptors such as iodine (I2), bromine (Br2), and picric acid (PiA) have been isolated in the solid state in a chloroform solvent at room temperature. Based on elemental analysis, UV-Vis, infrared, and 1H NMR spectra, and thermogravimetric analysis (TG/DTG) of the solid CTC, [(Schiff)(I2)] (1), [(Schiff)(Br2)] complexes with a ratio of 1:1 and [(Schiff)(PiA)3] complexes with 1:3 have been prepared. In the picric acid complex, infrared and 1H NMR spectroscopic data indicate that the charge-transfer interaction is associated with a hydrogen bonding, whereas the iodine and bromine complexes were interpreted in terms of the formation of dative ion pairs [Schiff+, I{2/•-}] and [Schiff+, Br{2/•-}], respectively. Kinetic parameters were obtained for each stage of thermal degradation of the CT complexes using Coats-Redfern and Horowitz-Metzger methods. DC electrical properties as a function of temperature of these charge transfer complexes have been studied.

  10. Synthesis, spectral, antitumor and antimicrobial studies on Cu(II) complexes of purine and triazole Schiff base derivatives

    NASA Astrophysics Data System (ADS)

    Amer, Said; El-Wakiel, Nadia; El-Ghamry, Hoda

    2013-10-01

    A series of copper (II) complexes of Schiff bases derived from 7H-2,6-diaminopurine and 4H-3,5-diamino-1,2,4-triazole with 2-pyridinecarbaldehyde, salicylaldehyde, 2,4-dihydroxybenzaldehyde and 2-hydroxy-1-naphthaldehyde have been prepared. The donor atoms and the possible geometry of the complexes were investigated by means of elemental and thermal analyses, molar conductance, magnetic moment, UV-Vis, IR, ESR and mass spectra. The ligands behaved as tetradentate, coordinating through the nitrogen atom of the azomethine group and the nearest nitrogen atom to it or oxygen atom of α-hydroxyl group. The results of simultaneous DTA & TGA analyses of the complexes showed the final degradation product for these complexes is CuO. The spectral studies confirmed a four coordinate environment around the metal ion. The obtained results were supported by 3D molecular modeling of complexes using molecular mechanics (MM+) and semiempirical molecular orbital calculations (PM3). These complexes were also tested for their in vitro antimicrobial activities against some bacterial and fungal strains. Complex 2 was investigated for its cyctotoxic effect against human breast cancer (MCF7), liver carcinoma (HEPG2) and colon carcinoma cell lines (HCT116). This compound exhibited a moderate activity against the tested cell lines with IC50 of 10.3, 9.8 and 8.7 μg/ml against MCF7, HCT116 and HEPG2, respectively.

  11. A novel bioactive tyramine derived Schiff base and its transition metal complexes as selective DNA binding agents

    NASA Astrophysics Data System (ADS)

    Raman, N.; Sobha, S.; Thamaraichelvan, A.

    2011-02-01

    A novel tyramine derived Schiff base, 3-4-dimethoxybenzylidene-4-aminoantipyrinyl-4-aminoethylphenol(L) and a series of its transition metal complexes of the type, ML 2Cl 2 where, M = Cu(II), Ni(II), Co(II) and Zn(II) have been designed and synthesized. Their structural features and other properties were deduced from the elemental analysis, magnetic susceptibility and molar conductivity as well as from mass, IR, UV-vis, 1H NMR and EPR spectral studies. The binding properties of these complexes with calf thymus DNA (CT-DNA) were investigated using electronic absorption spectroscopy, viscosity measurement, cyclic voltammetry and molecular docking analysis. The results reveal that the metal(II) complexes interact with DNA through minor groove binding. The interaction has also been investigated by gel electrophoresis. Interestingly, it was found that all the complexes could cleave the circular plasmid pUC19 super coiled (SC) DNA efficiently in the presence of AH 2 (ascorbic acid). The complexes showed enhanced antifungal and antibacterial activities compared to the free ligand.

  12. Synthesis, Characterization, DNA Interaction, and Antitumor Activities of La (III) Complex with Schiff Base Ligand Derived from Kaempferol and Diethylenetriamine

    PubMed Central

    Wang, Qin; Huang, Yu; Zhang, Jin-Sheng; Yang, Xin-Bin

    2014-01-01

    A novel La (III) complex, [LaL(H2O)3]NO3·3H2O, with Schiff base ligand L derived from kaempferol and diethylenetriamine, has been synthesized and characterized by elemental analysis, IR, UV-visible, 1H NMR, thermogravimetric analysis, and molar conductance measurements. The fluorescence spectra, circular dichroism spectra, and viscosity measurements and gel electrophoresis experiments indicated that the ligand L and La (III) complex could bind to CT-DNA presumably via intercalative mode and the La (III) complex showed a stronger ability to bind and cleave DNA than the ligand L alone. The binding constants (Kb) were evaluated from fluorescence data and the values ranged from 0.454 to 0.659 × 105 L mol−1 and 1.71 to 17.3 × 105 L mol−1 for the ligand L and La (III) complex, respectively, in the temperature range of 298–310 K. It was also found that the fluorescence quenching mechanism of EB-DNA by ligand L and La (III) complex was a static quenching process. In comparison to free ligand L, La (III) complex exhibited enhanced cytotoxic activities against tested tumor cell lines HL-60 and HepG-2, which may correlate with the enhanced DNA binding and cleaving abilities of the La (III) complex. PMID:25371657

  13. Chemistry, photophysics, and ultrafast kinetics of two structurally related Schiff bases containing the naphthalene or quinoline ring

    NASA Astrophysics Data System (ADS)

    Fita, P.; Luzina, E.; Dziembowska, T.; Radzewicz, Cz.; Grabowska, A.

    2006-11-01

    The two structurally related Schiff bases, 2-hydroxynaphthylidene-(8-aminoquinoline) (HNAQ) and 2-hydroxynaphthylidene-1'-naphthylamine (HNAN), were studied by means of steady-state and time resolved optical spectroscopies as well as time-dependent density functional theory (TDDFT) calculations. The first one, HNAQ, is stable as a keto tautomer in the ground state and in the excited state in solutions, therefore it was used as a model of a keto tautomer of HNAN which exists mainly in its enol form in the ground state at room temperature. Excited state intramolecular proton transfer in the HNAN molecule leads to a very weak (quantum yield of the order of 10-4) strongly Stokes-shifted fluorescence. The characteristic time of the proton transfer (about 30fs) was estimated from femtosecond transient absorption data supported by global analysis and deconvolution techniques. Approximately 35% of excited molecules create a photochromic form whose lifetime was beyond the time window of the experiment (2ns). The remaining ones reach the relaxed S1 state (of a lifetime of approximately 4ps), whose emission is present in the decay associated difference spectra. Some evidence for the back proton transfer from the ground state of the keto form with the characteristic time of approximately 13ps was also found. The energies and orbital characteristics of main electronic transitions in both molecules calculated by TDDFT method are also discussed.

  14. Synthesis, structure, protein binding of Cu(II) complexes with a tridentate NNO Schiff-base ligand.

    PubMed

    Li, Mei; Huang, ShuJuan; Ye, Cheng; Xie, YongRong

    2015-11-01

    Four new Cu(II) complexes (1, 2, 3 and 4) in the presence of different anions (Cl(-), Br(-), I(-) and ClO4(-)) have been prepared by tridentate NNN Schiff-base ligand (N,N-dimethyl-N'-[phenyl(2-pyridyl)methylene]ethane-1,2-diamine) and well characterized by single-crystal X-ray diffraction, elemental analysis, IR and UV-Vis spectroscopy. The interactions of complexes 1-4 with human serum albumin (HSA) have been investigated in Tris-HCl buffer solution at pH 7.4 by spectroscopic methods and a molecular docking technique. Experimental results proved that the four complexes quench the fluorescence of HSA through a static quenching mechanism. Thermodynamic parameters were calculated from Van't Hoff equation. The distance r between the donor (HSA) and acceptor (complexes 1-4) has been obtained by means of Frester resonance energy transfer (FRET). Molecular docking results indicated that the main active binding sites for complexes 1, 2 and 4 are site III in subdomain IB and for complex 3 is site II in subdomain III A. The combination of molecular docking results and fluorescence experimental results indicate that the interaction between 1-4 and HSA are dominated by hydrophobic forces as well as hydrogen bonds. PMID:26056979

  15. Synthesis, structure and biological activity of cobalt(II) and copper(II) complexes of valine-derived schiff bases.

    PubMed

    Lv, Jian; Liu, Tingting; Cai, Sulan; Wang, Xin; Liu, Lei; Wang, Yongmei

    2006-11-01

    We have synthesized two cobalt(II) 2 and copper(II) 3 complexes of valine-derived Schiff bases. The obtained complexes were characterized by elemental analysis, FT-IR and X-ray diffraction. Biological studies of complexes 2 and 3 had been carried out in vitro for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi. Compound 3 was proven to be a broad spectrum agent, showed a significant inhibition of the growth of Gram-positive bacteria (Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, Micrococcus luteus), and pathogenic fungi (Candida spp., Cryptococcus neoformans, Rhodothece glutinis, Saccharomyces cerevisia, Aspergillus spp., Rhizopus nigricans) tested and a moderate activity against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Enterobacter aerogenes) tested. The in vitro cytotoxicity of compound 3 was evaluated using hemolytic assay, in which the compound 3 was found to be non-toxic to human erythrocytes even at a concentration of 500mug/mL. PMID:16965817

  16. Experimental, theoretical and docking studies of 2-hydroxy Schiff base type compounds derived from 2-amino-4-chlorobenzenethiol

    NASA Astrophysics Data System (ADS)

    Kusmariya, Brajendra S.; Mishra, A. P.

    2015-12-01

    We report here synthesis, DFT, Docking and Fluorescence studies of three Schiff base organic compounds viz. 2-{(E)-[(5-chloro-2-sulfanylphenyl)imino]methyl}phenol (1); 2,4-dichloro-6-{(E)-[(5-chloro-2-sulfanylphenyl)imino]methyl}phenol (2) and 2-{(E)-[(5-chloro-2-sulfanylphenyl) imino] methyl}-5-(diethylamino) phenol (3). These compounds have been characterized by elemental, FTIR, electronic and 1H NMR spectral techniques. Spectroscopic studies reveal that all the compounds exist in enol-form in the solid state whereas keto and enol, both forms exist in solution. The fluorescence behavior has been studied in DMF solvents and 1 &2 compound exhibit more efficient fluorescence properties. The molecular geometry of all the compounds in the ground state has been computed using the Hartree-Fock (HF) and density functional theory (DFT) with the 6-31++G basis set. The theoretical electronic absorption spectra of the compounds have been predicted using TD-DFT and TD-HF methods and compared with experimental spectral results. The predicted nonlinear optical properties of all the compounds are higher than those of urea. In addition to DFT calculations; frequency calculations, mulliken charge distribution, HOMO-LUMO and molecular electrostatic potential (MEP) have also been computed at the same level of theory. Molecular docking studies of the compounds in the active site of CAII (PDB code: 1CNX) have been performed to predict their possible binding modes in the active site of target carbonic anhydrase II enzyme.

  17. Structure-Activity Relationships for Some Diamine, Triamine and Schiff Base Derivatives and Their Copper(II) Complexes

    PubMed Central

    Bolos, C. A.; Nikolov, G. St.; Ekateriniadou, L.; Kortsaris, A.; Kyriakidis, D. A.

    1998-01-01

    Ethylenediamine (en), putrescine (pu), diethylenetriamine (dien), dipropylenetriamine (dpta), spermidine (spmd) and their CuII compounds as well as the Schiff bases with 2-furaldehyde (dienOO), 2- thiophenecarboxaldehyde (dienSS) and pyrrole-2-carboxaldehyde (dienNN) of dien and that of dpta with 2- thiophenecarboxaldehyde (dptaSS), were prepared and characterised. They were tested against Bacillus substilis, Bacillus cereus, Staphylococcus aureus, Escherichia coli, Proteus vulgaris and Xanthomonas campestris as antibacterial reagents, the highest activity being exhibited by Cu(dptaSS)(NO3)2 complex, which acts as antibiotic. In the antiproliferative tests (vs. T47D,L929 and BHK21/c13 cell lines) the best results were obtained with Cu(dptaSS)2+ and Cu(dienSS)2+. Electronic structure calculations gave for dptaSS and dienSS the higher negative charges on the N atoms. The counter-ions (Br-, NO3- and SO42-) play an important role by modulating the reagent's selectivity versus the bacteria [Gram(+) or Gram(-)], but they have no effect on the antiproliferative activity. PMID:18475868

  18. Synthesis, spectroscopy, X-ray crystallography, DFT calculations, DNA binding and molecular docking of a propargyl arms containing Schiff base.

    PubMed

    Balakrishnan, C; Subha, L; Neelakantan, M A; Mariappan, S S

    2015-11-01

    A propargyl arms containing Schiff base (L) was synthesized by the condensation of 1-[2-hydroxy-4-(prop-2-yn-1-yloxy)phenyl]ethanone with trans-1,2-diaminocyclohexane. The structure of L was characterized by IR, (1)H NMR, (13)C NMR and UV-Vis spectroscopy and by single crystal X-ray diffraction analysis. The UV-Visible spectral behavior of L in different solvents exhibits positive solvatochromism. Density functional calculation of the L in gas phase was performed by using DFT (B3LYP) method with 6-31G basis set. The computed vibrational frequencies and NMR signals of L were compared with the experimental data. Tautomeric stability study inferred that the enolimine is more stable than the ketoamine form. The charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Electronic absorption and emission spectral studies were used to study the binding of L with CT-DNA. The molecular docking was done to identify the interaction of L with A-DNA and B-DNA. PMID:26093117

  19. Synthesis, structural characterization, fluorescence, antimicrobial, antioxidant and DNA cleavage studies of Cu(II) complexes of formyl chromone Schiff bases

    NASA Astrophysics Data System (ADS)

    Kavitha, P.; Saritha, M.; Laxma Reddy, K.

    2013-02-01

    Cu(II) complexes have been synthesized from different Schiff bases, such as 3-((2-hydroxy phenylimino)methyl)-4H-chromen-4-one (HL1), 2-((4-oxo-4H-chromen-3-yl)methylneamino) benzoicacid (HL2), 3-((3-hydroxypyridin-2-ylimino)methyl)-4H-chromen-4-one (HL3) and 3-((2-mercaptophenylimino)methyl)-4H-chromen-4-one (HL4). The complexes were characterized by analytical, molar conductance, IR, electronic, magnetic, ESR, thermal, powder XRD and SEM studies. The analytical data reveal that metal to ligand molar ratio is 1:2 in all the complexes. Molar conductivity data indicates that all the Cu(II) complexes are neutral. On the basis of magnetic and electronic spectral data, distorted octahedral geometry is proposed for all the Cu(II) complexes. Thermal behaviour of the synthesized complexes illustrates the presence of lattice water molecules in the complexes. X-ray diffraction studies reveal that all the ligands and their Cu(II) complexes have triclinic system with different unit cell parameters. Antimicrobial, antioxidant and DNA cleavage activities indicate that metal complexes exhibited greater activity as compared with ligands.

  20. Cu(II) and Pd(II) complexes of water soluble O-carboxymethyl chitosan Schiff bases: Synthesis, characterization.

    PubMed

    Baran, Talat; Menteş, Ayfer

    2015-08-01

    This study reports the synthesis of two new water soluble O-carboxymethyl chitosan Schiff bases (OCMCS-5 and OCMCS-6a) and their Cu(II) and Pd(II) complexes. Characterizations of these complexes were carried out with FTIR, elemental analysis, (13)C CPMAS, UV-vis, magnetic moment and molar conductivity techniques. The degrees of substitution (DS) for OCMCS-5a and OCMCS-6a were determined to be 0.48 and 0.44 in elemental analysis. The solubility test revealed that OCMCS-5a and OCMCS-6a dissolved thoroughly in water. The surface morphologies of chitosan (CS), OCMCS-5a, OCMCS-6a and their complexes were studied with SEM-EDAX. Thermal stability of the synthesized compounds was evaluated by TG/DTG and their crystallinity values were investigated with powder X-ray diffraction. Cu(II) and Pd(II) contents of the complexes were estimated with ICP-OES. The characterization studies demonstrated that the thermal stability and crystallinity values of the OCMCS-5a and OCMCS-6a were lower than those of CS. PMID:26021275

  1. Investigation of irradiated rats DNA in the presence of Cu(II) chelates of amino acids Schiff bases.

    PubMed

    Karapetyan, N H; Torosyan, A L; Malakyan, M; Bajinyan, S A; Haroutiunian, S G

    2016-01-01

    The new synthesized Cu(II) chelates of amino acids Schiff bases were studied as a potential radioprotectors. Male albino rats of Wistar strain were exposed to X-ray whole-body irradiation at 4.8 Gy. This dose caused 30% mortality of the animals (LD30). The survival of animals exposed to radiation after preliminary administration of 10 mg/kg Cu(II)(Nicotinyl-l-Tyrosinate)2 or Cu(II)(Nicotinyl-l-Tryptophanate)2 prior to irradiation was registered about 80 and 100% correspondingly. Using spectrophotometric melting and agarose gel electrophoresis methods, the differences between the DNA isolated from irradiated rats and rats pretreated with Cu(II) chelates were studied. The fragments of DNA with different breaks were revealed in DNA samples isolated from irradiated animals. While, the repair of the DNA structure was observed for animals pretreated with the Cu(II) chelates. The results suggested that pretreatment of the irradiated rats with Cu(II)(Nicotinyl-l-Tyrosinate)2 and Cu(II)(Nicotinyl-l-Tryptophanate)2 compounds improves the liver DNA characteristics. PMID:26101796

  2. Synthesis, structural elucidation and bioevaluation of 4-amino-1,2,4-triazole-3-thione's Schiff base derivatives.

    PubMed

    Rafiq, Muhammad; Saleem, Muhammad; Hanif, Muhammad; Kang, Sung Kwon; Seo, Sung-Yum; Lee, Ki Hwan

    2016-02-01

    In this study, a series of ten triazole Schiff base derivatives 6a-j were synthesized through microwave assisted imine formation by reacting substituted amino triazole 5 with different substituted aldehydes. All the synthesized compounds were evaluated for their inhibitory activity against mushroom tyrosinase. Two of the compounds 6a and 6b among the series 6a-j were found to be highly potent tyrosinase inhibitors with IC50 values of 10.09 ± 1.03 and 6.23 ± 0.85 µM, respectively, which were even higher than that of the reference inhibitor kojic acid (IC50 = 16.6 ± 2.8 µM). Compounds 6e and 6f with IC50 values of 20.27 ± 2.78 and 26.02 ± 4.14 µM, respectively, were comparable to the reference inhibitor, and the remaining compounds had a moderate inhibitory activity against mushroom tyrosinase. The most potent compounds (6a, 6b) were used in the kinetic and optical analyses. The inhibition kinetics analyzed with Lineweaver-Burk plots revealed that both compounds 6a and 6b were non-competitive inhibitors of tyrosinase with inhibition constant values of 0.023 and 0.022 mM, respectively. PMID:26608953

  3. Structure investigation of three hydrazones Schiff's bases by spectroscopic, thermal and molecular orbital calculations and their biological activities

    NASA Astrophysics Data System (ADS)

    Belal, Arafa A. M.; Zayed, M. A.; El-Desawy, M.; Rakha, Sh. M. A. H.

    2015-03-01

    Three Schiff's bases AI (2(1-hydrazonoethyl)phenol), AII (2, 4-dibromo 6-(hydrazonomethyl)phenol) and AIII (2(hydrazonomethyl)phenol) were prepared as new hydrazone compounds via condensation reactions with molar ratio (1:1) of reactants. Firstly by reaction of 2-hydroxy acetophenone solution and hydrazine hydrate; it gives AI. Secondly condensation between 3,5-dibromo-salicylaldehyde and hydrazine hydrate gives AII. Thirdly condensation between salicylaldehyde and hydrazine hydrate gives AIII. The structures of AI-AIII were characterized by elemental analysis (EA), mass (MS), FT-IR and 1H NMR spectra, and thermal analyses (TG, DTG, and DTA). The activation thermodynamic parameters, such as, ΔE∗, ΔH∗, ΔS∗ and ΔG∗ were calculated from the TG curves using Coats-Redfern method. It is important to investigate their molecular structures to know the active groups and weak bond responsible for their biological activities. Consequently in the present work, the obtained thermal (TA) and mass (MS) practical results are confirmed by semi-empirical MO-calculations (MOCS) using PM3 procedure. Their biological activities have been tested in vitro against Escherichia coli, Proteus vulgaris, Bacillissubtilies and Staphylococcus aurous bacteria in order to assess their anti-microbial potential.

  4. Schiff base - Chitosan grafted l-monoguluronic acid as a novel solid-phase adsorbent for removal of congo red.

    PubMed

    Yuan, Bo; Qiu, Li-Gan; Su, Hong-Zhen; Cao, Cheng-Liang; Jiang, Ji-Hong

    2016-01-01

    A novel modified chitosan adsorbent (GL-SBCS) was synthesized by covalently grafting a Schiff base-chitosan (SBCS) onto the surface of l-monoguluronic acid. Physico-chemical investigation on the adsorption of congo red, an anionic azo dye by GL-SBCS has been carried out. The effect of different weight contents of chitosan in GL-SBCS composite, adsorbent dosage, initial pH and contract time were studied in detail using batch adsorption. Results showed that GL-SBCS exhibited better than normal CS and l-monoguluronic acid. Further investigation demonstrated that the adsorption pattern fitted well with the Langmuir model (R(2)>0.99) but less-satisfied the Freundlich model. Both ionic interaction as well as physical forces is responsible for binding of congo red with GL-SBCS as determined by zeta potential measurement Both sodium chloride and sodium dodecyl sulfate significantly influenced the adsorption process. SBCS would be a good method and resource to increase absorption efficiency for the removal of anionic dyes in a wastewater treatment process. PMID:26432372

  5. Synthesis, spectroscopic, structural characterization, electrochemical and antimicrobial activity studies of the Schiff base ligand and its transition metal complexes

    NASA Astrophysics Data System (ADS)

    Aslanta?, Mehmet; Kendi, Engin; Demir, Necmettin; ?abik, Ali E.; Tmer, Mehmet; Kertmen, Metin

    2009-10-01

    In this study, the Schiff base ligand trans-N,N'-bis[(2,4-dichlorophenyl) methylidene] cyclohexane-1,2-diamine (L) and its copper(II), nickel(II) and palladium(II) transition metal complexes were prepared and characterized by the analytical and spectroscopic methods. The 1H( 13C) NMR spectra of the ligand and its diamagnetic complexes were recorded in DMSO-d 6 solvent and obtained data confirm that the nitrogen atoms of the imine groups coordinated to the metal ions. Electrochemical properties of the ligand and its metal complexes were investigated in the DMF solvent at the 100 and 250 mV s -1 scan rates. The ligand and metal complexes showed both reversible and irreversible processes at these scan rates. The single crystal of the ligand (L) was obtained from MeOH solution, and its crystal structure was determined by X-ray diffraction. The C-H⋯Cl hydrogen bonding interactions in the molecule were seen which increase the stability of the crystal structure. The antimicrobial activity studies of the ligand and its metal complexes were carried out by using the various bacteria and fungi.

  6. Experimental and theoretical investigation of a pyridine containing Schiff base: Hirshfeld analysis of crystal structure, interaction with biomolecules and cytotoxicity

    NASA Astrophysics Data System (ADS)

    Chithiraikumar, S.; Neelakantan, M. A.

    2016-03-01

    A pyridine containing Schiff base (E)-2-methoxy-6-(((pyridin-2-ylmethyl)imino)methyl) phenol (L) was isolated in single crystals. The molecular structure of L was studied by FT-IR, NMR, UV-Vis techniques, single crystal XRD analysis and computationally by DFT method. L prefers enol form in the solid state. Electronic spectrum of L was recorded in different organic solvents to investigate the dependence of tautomerism on solvent types. The polar solvents facilitate the proton transfer by decreasing the activation energy needed for transition state. Potential energy curve for the intramolecular proton transfer in the ground state is generated in gas and solution phases. The 3D Hirshfeld surfaces and the associated 2D fingerprint plots were investigated. The percentages of various interactions were analyzed by fingerprint plots of Hirshfeld surface. The interaction of L with CT DNA was investigated under physiological conditions using UV-Vis spectroscopy, fluorescence quenching and molecular docking methods. Molecular docking studies reveal that binding of L to the groove of B-DNA is through hydrogen bonding and hydrophobic interactions. The in vitro cytotoxicity of L was carried out in two different human tumor cell lines, MCF 7 and MIA-Pa-Ca-2 exhibits moderate activity.

  7. Synthesis and characterization of water soluble O-carboxymethyl chitosan Schiff bases and Cu(II) complexes.

    PubMed

    Baran, Talat; Mente?, Ayfer; Arslan, Hlya

    2015-01-01

    In this study, mono-imine was synthesized (3a and 4a) via a condensation reaction between 2,4-pentadion and aminobenzoic acid (meta or para) in alcohol (1:1). The second-imine (CS-3a and CS-4a) was obtained as a result of the reaction of the free oxo groups of mono-imine (3a and 4a) with the amino groups on the chitosan (CS). Their structures were characterized with FTIR and (13)C CP-MAS. Then, the water soluble forms of CS-3a and CS-4a were obtained through oxidation of the hydroxide groups on the chitosan to carboxymethyl groups using monochloracetic acid ([O-CMCS-3a] 2H2O and [O-CMCS-4a] 2H2O). Thus, the solubility problem of chitosan in an aqueous media was overcome and Cu(II) complexes could be synthesized more easily. Characterization of the synthesized O-carboxymethyl chitosan Schiff base derivatives and their metal complexes, [O-CMCS-3a-Cu(OAc)2] 2H2O and [O-CMCS-4a-Cu(OAc)2] 2H2O, was conducted using FTIR, UV-Vis, TG/DTA, XRD, SEM, elemental analysis, conductivities and magnetic susceptibility measurements. PMID:25128824

  8. Structure and aggregation properties of a Schiff-base zinc(II) complex derived from cis-1,2-diaminocyclohexane.

    PubMed

    Consiglio, Giuseppe; Oliveri, Ivan Pietro; Punzo, Francesco; Thompson, Amber L; Di Bella, Santo; Failla, Salvatore

    2015-08-01

    This contribution explores the effect of the bridging diamine upon the aggregation properties of a Zn(II) Schiff-base complex, , both in the solid state and in solution. The X-ray structure of , resulting from the harvest of good quality crystals using chloroform and diethyl ether as solvents, shows the presence of a densely packed dimer in the solid state which pentacoordinates two Zn atoms involved in a ?-phenoxo bridge. Detailed studies in solution, through (1)H NMR, DOSY NMR, and optical spectroscopic investigations, indicate the typical aggregation/deaggregation behaviour on switching from non-coordinating to coordinating solvents, in relation to the Lewis acidic character of such Zn(II) complexes. Thus, while in DMSO-d6 both (1)H NMR and DOSY studies suggest the existence of monomeric species, in chloroform solution experimental data support the existence of aggregates. However, unlike our previous studies, (1)H NMR data in chloroform solution indicate the existence of an asymmetric dimer, as observed in the X-ray crystal structure. This further evidences a very rigid backbone of the dimeric aggregate and can be related to the defined stereochemistry of the chelate cis-1,2-diaminocyclohexane bridge. PMID:26103462

  9. Rod shaped oxovanadium(IV) Schiff base complexes: Synthesis, mesomorphism and influence of flexible alkoxy chain lengths

    NASA Astrophysics Data System (ADS)

    Gupta, Bishop Dev; Datta, Chitraniva; Das, Gobinda; Bhattacharjee, Chira R.

    2014-06-01

    A series of oxovanadium(IV) complexes of bidentate [N,O] donor Schiff-base ligands of the type [VO(L)2], [L = N-(4-n-alkoxysalicylaldimine)-4?-octadecyloxyaniline, n = 8, 10, 12, 14, 16 and 18] have been synthesized. The compounds were characterized by elemental analyses, Fourier transform infrared spectroscopy (FTIR), 1H, 13C nuclear magnetic resonance (NMR), ultraviolet-visible spectroscopy (UV-Vis), and fast atom bombardment (FAB) mass spectrometry. The mesomorphic behavior of the compounds was studied by polarized optical microscopy (POM) and differential scanning calorimetry (DSC). The ligands and complexes are all thermally stable exhibiting smectic mesomorphism. The ligands 8-OR to16-OR show SmC phase at ?113-118 C and an unidentified SmX phase reminiscent of soft crystal at ?77-91 C whereas the complexes all showed SmA phases. Interestingly the complexes with C10 and C12 alkoxy chain length exhibited additionally SmC phases also. The melting points of the ligands linearly increases whereas mesophase to isotropic transition temperature decreases as a function of increasing carbon chain length of alkoxy arm while no trend was apparently noticeable for the complexes.

  10. Retinal shows its true colours: photoisomerization action spectra of mobility-selected isomers of the retinal protonated Schiff base.

    PubMed

    Coughlan, N J A; Adamson, B D; Gamon, L; Catani, K; Bieske, E J

    2015-09-21

    Retinal is one of Nature's most important and widespread chromophores, exhibiting remarkable versatility in its function and spectral response, depending on its protein environment. Reliable spectroscopic and photochemical data for the isolated retinal molecule are essential for calibrating theoretical approaches that seek to model retinal's behaviour in complex protein environments. However, due to low densities and possible co-existence of multiple isomers, retinal is a challenging target for gas-phase investigations. Here, the photoisomerization behaviour of the trans isomer of the retinal protonated Schiff base (RPSB) is investigated in the gas phase by irradiating mobility-selected RPSB ions with tunable light in a tandem ion mobility spectrometer. trans RPSB ions are converted to single cis isomers and also more compact isomers through irradiation with visible light. The S1? S0 photoisomerization action spectrum of trans RPSB, obtained by monitoring production of cis isomers as a function of wavelength, exhibits a single well-defined peak with a maximum at 618 5 nm. Corresponding action spectra of cis RPSB isomers exhibit broader peaks, conclusively demonstrating an isomeric dependence for the RPSB spectrum in the gas phase. PMID:26280514

  11. Environmental Dependence of Artifact CD Peaks of Chiral Schiff Base 3d-4f Complexes in Soft Mater PMMA Matrix

    PubMed Central

    Okamoto, Yu; Nidaira, Keisuke; Akitsu, Takashiro

    2011-01-01

    Four chiral Schiff base binuclear 3d-4f complexes (NdNi, NdCu, GdNi, and GdCu) have been prepared and characterized by means of electronic and CD spectra, IR spectra, magnetic measurements, and X-ray crystallography (NdNi). A so-called artifact peak of solid state CD spectra, which was characteristic of oriented molecules without free molecular rotation, appeared at about 470 nm. Magnetic data of the complexes in the solid state (powder) and in PMMA cast films or solutions indicated that only GdCu preserved molecular structures in various matrixes of soft maters. For the first time, we have used the changes of intensity of artifact CD peaks to detect properties of environmental (media solid state (KBr pellets), PMMA cast films, concentration dependence of PMMA in acetone solutions, and pure acetone solution) for chiral 3d-4f complexes (GdCu). Rigid matrix keeping anisotropic orientation exhibited a decrease in the intensity of the artifact CD peak toward negative values. The present results suggest that solid state artifact CD peaks can be affected by environmental viscosity of a soft mater matrix. PMID:22072930

  12. Synthesis, characterization, electrochemical and biological studies on some metal(II) Schiff base complexes containing quinoxaline moiety

    NASA Astrophysics Data System (ADS)

    Justin Dhanaraj, Chellaian; Johnson, Jijo

    2014-01-01

    Novel Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff base derived from quinoxaline-2,3-(1,4H)-dione and 4-aminoantipyrine (QDAAP) were synthesized. The ligand and its complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, FTIR, UV-Vis., mass and 1H NMR spectral studies. The X band ESR spectrum of the Cu(II) complex at 300 and 77 K were also recorded. Thermal studies of the ligand and its complexes show the presence of coordinated water in the Ni(II) and Zn(II) complexes. The coordination behavior of QDAAP is also discussed. All the complexes are mono nuclear and tetrahedral geometry was found for Co(II) complex. For the Ni(II) and Zn(II) complexes, octahedral geometry was assigned and for the Cu(II) complex, square planar geometry has been suggested. The grain size of the complexes was estimated using powder XRD. The surface morphology of the compounds was studied using SEM analysis. Electrochemical behavior of the synthesized complexes in DMF at room temperature was investigated by cyclic voltammetry. The in vitro biological screening of QDAAP and its metal complexes were tested against bacterial species Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. The fungal species include Aspergillus niger, Aspergillus flavus and Candida albicans. The DNA cleavage activity of QDAAP and its complexes were also discussed.

  13. Palladium(II) chelate of tetradentate Schiff base as mixed stationary phase for gas chromatography.

    PubMed

    Laghari, Abdul J; Khuhawar, Muhammad Y; Ali, Zeenat M

    2007-02-01

    Bis(acetylacetone)ethylenediiminepalladium(II) (PdAA2en) was examined as a mixed stationary phase with OV-1 on Chromosorb G/NAW 60-80 mesh size for the GC separation of aromatic hydrocarbons, heteroaromatics, alcohols, aldehydes, ketones, esters, and nitro compounds. Forty-two compounds were examined and the GC results were compared with those obtained with 3% OV-1 on Chromosorb G/NAW 60-80 mesh size under similar operating conditions. Improved resolution, peak asymmetry, theoretical plate numbers, and Kovats indices were obtained on the mixed stationary phase of 3% OV-1 + 5% PdAA2en compared to 3% OV-1 column. The stability constant (Km), enthalpies (deltaH), entropies (deltaS), and Gibbs free energies (deltaG) of the GC elution on the column (2 m x 3 mm id) packed with 3% OV-1 + 5% PdAA2en on Chromosorb G/NAW 60-80 mesh size have been calculated. Donor-acceptor complexation in the gas phase is indicated by negative values of enthalpy (-deltaH) within 5.81 to 10.89 kcal/mol and Gibbs free energy (-deltaG) from 1.34 to 4.08 kcal/mol. The retention time transformations on both the phases were calculated and the ratios obtained from the stationary phases 3% OV-1 and 3% OV-1 + 5% PdAA2en were plotted on the x-axis and the y-axis, respectively, and the coefficients of determination for alkanes, aromatic and heteroaromatics, ketones, and alcohols were observed to lie within 0.5253 to 0.9742, indicative of some different kinds of interaction of the two stationary phases with the solutes. PMID:17396594

  14. Selective recognition of sulfate anions in a 95% ethanol solvent with a simple neutral salicylaldehyde dansyl hydrazine Schiff base tuned by Brnsted-Lowry acid-base reaction.

    PubMed

    Wei, Gao-Ning; Zhang, Jing-Li; Jia, Cang; Fan, Wei-Zhen; Lin, Li-Rong

    2014-07-15

    A new Schiff base compound, 5-(dimethylamino)-N'-(2-hydroxybenzylidene)naphthalene-1-sulfonohydrazide (R), has been synthesized, characterized, and employed as a selective fluorescence receptor for the recognition of sulfate anions. UV-vis absorption, fluorescence emission, (1)H NMR spectra and DFT calculation studies on the system have been carried out to determine the nature of the interactions between R and anions. The results reveal that the deprotonation of the phenol without the need of a strong base leads to the formation of a hydrogen-bonding complex with a -SO2-NH- group, which is responsible for the spectra changes. The deprotonation process for the selectivity recognition of sulfate can be tuned by the Brnsted-Lowry acid-base reaction in nonaqueous solutions, revealing that suitable phenolic hydroxyl acidity is the key factor for anion recognition selectivity. PMID:24667421

  15. Triphenylamine-based Schiff bases as the High sensitive Al(3+) or Zn(2+) fluorescence turn-on probe: Mechanism and application in vitro and in vivo.

    PubMed

    Li, Wei; Tian, Xiaohe; Huang, Bei; Li, Huijuan; Zhao, Xiaoyu; Gao, Shan; Zheng, Jun; Zhang, Xiuzhen; Zhou, Hongping; Tian, Yupeng; Wu, Jieying

    2016-03-15

    Two novel similar structural triphenylamine-based Schiff base fluorescent probes (L1/L2) were designed, prepared and characterized. Distinctive recognition mechanisms of L1 and L2 toward Al(3+) and Zn(2+) have been established by UV/vis, fluorescence spectra, mass spectra and (1)H NMR studies, respectively. To further explore their utility in biological system, L2 was selected as a probe for live cell endogenous Zn(2+) indicator and showed superb sensitivity on Zn(2+) intracellular distribution. Furthermore, L2 was employed to selectively detect Zn(2+) in live tissues at both extracellular and intracellular level, qualitatively indicated varies zinc concentration as a function of different organs. PMID:26469730

  16. Oxidation of phenyl propyne catalyzed by copper(II) complexes of a benzimidazolyl schiff base ligand: Effect of acid/base, oxidant, surfactant and morphology

    NASA Astrophysics Data System (ADS)

    Kumar, Ravinder; Mathur, Pavan

    2015-02-01

    Copper(II) complexes with a new N-Substituted benzimidazolyl schiff base ligand are used as catalyst for the oxidation of 1-phenyl propyne. The oxidation is carried out under mild conditions using stoichiometric amounts of oxidant and catalytic amounts of Cu(II) complex as catalyst. Effect of acid/base, oxidant, morphology and surfactant has been studied. Two major products of phenyl propyne oxidation are the ?-diketonic product and a terminal aldehyde. Diketone is the major product under acidic conditions while aldehyde formation is highest under basic conditions. The maximum conversion is found with the NO3- bound complex. GC-MS is used to find the percentage yields of products. SEM and PXRD of the reused complexes as catalyst suggest that morphology affects the catalytic efficiency.

  17. Mechanism of isomerization of 11-cis-retinal in lipid dispersions by aromatic amines

    SciTech Connect

    Fulton, B.S.; Rando, R.R.

    1987-01-13

    It has previously been shown that retinotoxic, primary aromatic amines catalyze the isomerization of 11-cis-retinal to its all-trans congener after Schiff base formation. This process led to the short-circuiting of the visual cycle and the observed retinotoxicity when it occurred in vivo. The catalysis was also observed to occur in vitro in phosphatidylcholine-based vesicles but not in hydrocarbon solutions. The rate of isomerization of an aromatic amine Schiff base of 11-cis-retinal in the phospholipid vesicles was typically 10/sup 3/-fold more rapid than in hydrocarbon solutions. In this article, the mechanistic basis of this apparently membrane-specific catalysis is described. It was found that the rate enhancement effect observed was independent of the lipid used. Moreover, a bilayer structure was not important because rate enhancements were also observed in micelles. The rapid isomerization rates observed in lipid dispersions appear not be free radical initiated because free radical quenching agents, such as ..cap alpha..-tocopherol and BETA-carotene, had little effect on the isomerization rates. It was further found that aliphatic amines, such as n-dodecylamine, could be substituted for the aromatic amines in phospholipid. Finally, and most importantly, it was found that the isomerization of the aromatic amine retinal Schiff bases in phospholipid vesicles was acid-catalyzed. It is concluded that the rate enhancements observed for the isomerization of 11-cis-retinal aromatic amine Schiff bases in lipid dispersions over that in hydrocarbon solvents are due to the occurrence of acid-base catalysis in the former.

  18. Structural insights into the counterion effects on the manganese(iii) spin crossover system with hexadentate Schiff-base ligands.

    PubMed

    Wang, Shi; Xu, Wu-Tan; He, Wen-Rui; Takaishi, Shinya; Li, Yong-Hua; Yamashita, Masahiro; Huang, Wei

    2016-04-01

    A series of new salts [Mn(5-MeO-sal-N-1,5,8,12)]Y (Y = ClO4 for 1, Y = BF4 for 2, Y = NO3 for 3 and Y = CF3SO3 for 4) based on the six-coordinated mononuclear manganese(iii) Schiff-base complex cation [Mn(5-MeO-sal-N-1,5,8,12)](+), has been investigated to determine the impact of counter anion effects, intramolecular ligand distortion and intermolecular supramolecular structures on the spin crossover (SCO) behavior. The SCO in salt 1 has resulted in a crystallographic observation of the coexistence of high-spin (HS, S = 2) and low-spin (LS, S = 1) manganese(iii) complex cations in equal proportions around 100 K. At room temperature, the two crystallographically distinct manganese centers are both close to the complete HS state. Only one of the two slightly different units undergoes SCO in the temperature range 300-180 K, whereas the other remains in the HS state down to 20 K. For salts 2 and 3, crystal structural analysis indicates change in the anion from ClO4(-) to BF4(-) and NO3(-) was led to the close arrangement of the cations and the stacking between phenyl groups from the ligands. With CF3SO3(-) as the counterion, although the cations and the anions separate clearly in one direction, the close arrangement of cations in other directions precludes the spin transformation of the Mn(iii) cations. Magnetic measurements on 2-4 indicate that the manganese(iii) complex cations remain in the HS state in the temperature range 2-300 K. PMID:26927027

  19. Molecular property investigations of an ortho-hydroxy Schiff base type compound with the first-principle molecular dynamics approach.

    PubMed

    Jezierska-Mazzarello, Aneta; Vuilleumier, Rodolphe; Panek, Jaros?aw J; Ciccotti, Giovanni

    2010-01-14

    The structure, proton transfer, and vibrational dynamics under ambient conditions of a selected ortho-hydroxy Schiff base type compound, 2-(N-methyl-alpha-iminoethyl)-4-chlorophenol, containing a very short intramolecular hydrogen bond, were investigated computationally in the gas phase and in the crystal by density functional theory (DFT) based first-principle molecular dynamics (FPMD). It is found that the proton is well localized on the nitrogen side of the O...H...N bridge in the crystal phase, in agreement with X-ray diffraction experiments, while a more labile proton is located most of the time on the oxygen side in a vacuum. Environmental effects on this very strong hydrogen bond thus appear crucial and lead to drastic changes of the infrared (IR) spectrum: The computed gas-phase IR spectrum shows a very broad absorption band that covers frequencies from about 1000 to 3000 cm(-1) assigned to the labile proton. In mere contrast, a much more localized absorption band around 2600-2700 cm(-1) is predicted in the crystal phase. Finally, effects of the quantization of the proton motion on the hydrogen bond structure were estimated in two ways. First, we constructed the one-dimensional (1D) potential energy surface (PES) for the proton along the O...H...N bridge in a vacuum. The 1D Schrodinger equation was then solved. Next, path integral molecular dynamics (PIMD) was performed in the solid state. Inclusion of quantum effects does not affect the observed change of the most probable tautomer, upon going from the gas phase to the crystal. PMID:20017543

  20. DFT study on second-order nonlinear optical properties of a series of mono Schiff-base M(II) (M = Ni, Pd, Pt) complexes

    NASA Astrophysics Data System (ADS)

    Liu, Chun-Guang; Qiu, Yong-Qing; Sun, Shi-Ling; Chen, Hui; Li, Na; Su, Zhong-Min

    2006-10-01

    A series of mono Schiff-base M(II) (M = Ni, Pd, Pt) complexes based on the crystal data are designed. Density Functional Theory (DFT) method was employed to investigate the second-order nonlinear optical (NLO) properties of all metal complexes. The results show that the second-order NLO properties of metal complexes are intensively sensitive to the exchange of donor/acceptor because of the differences of the extent of charge separation and the intraligand charge transfer (ILCT) processes. The metal ions do not offer direct contributions to second-order NLO responses because they are as electron bridges for transferring electrons in CT processes.

  1. Bond descriptors based on kinetic energy densities reveal regions of slow electrons - Another look at aromaticity

    NASA Astrophysics Data System (ADS)

    Jacobsen, Heiko

    2013-09-01

    An analysis of the kinetic energy density within a molecule identifies patterns within its electronic structure that are intuitively linked to familiar concepts of chemical bonding. Proposed are bond descriptors based on local kinetic energies in an extended mapping onto a finite range of values, so called RoSE-indicators. The usefulness and performance of RoSE-indicators is judged in applications on aromaticity. Results are presented for benzene, cyclobutadiene, borazine and the cyclic hydrogen fluoride trimer as examples for agreed-upon aromaticity and antiaromaticity, as well as for questionable aromaticity. All-metal aromaticity is discussed based on results obtained for tetra aluminum dianion.

  2. Multifunctional Electrochemical Platforms Based on the Michael Addition/Schiff Base Reaction of Polydopamine Modified Reduced Graphene Oxide: Construction and Application.

    PubMed

    Huang, Na; Zhang, Si; Yang, Liuqing; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2015-08-19

    In this paper, a new strategy for the construction of multifunctional electrochemical detection platforms based on the Michael addition/Schiff base reaction of polydopamine modified reduced graphene oxide was first proposed. Inspired by the mussel adhesion proteins, 3,4-dihydroxyphenylalanine (DA) was selected as a reducing agent to simultaneously reduce graphene oxide and self-polymerize to obtain the polydopamine-reduced graphene oxide (PDA-rGO). The PDA-rGO was then functionalized with thiols and amines by the reaction of thiol/amino groups with quinine groups of PDA-rGO via the Michael addition/Schiff base reaction. Several typical compounds containing thiol and/or amino groups such as 1-[(4-amino)phenylethynyl] ferrocene (Fc-NH2), cysteine (cys), and glucose oxidase (GOx) were selected as the model molecules to anchor on the surface of PDA-rGO using the strategy for construction of multifunctional electrochemical platforms. The experiments revealed that the composite grafted with ferrocene derivative shows excellent catalysis activity toward many electroactive molecules and could be used for individual or simultaneous detection of dopamine hydrochloride (DA) and uric acid (UA), or hydroquinone (HQ) and catechol (CC), while, after grafting of cysteine on PDA-rGO, simultaneous discrimination detection of Pb(2+) and Cd(2+) was realized on the composite modified electrode. In addition, direct electron transfer of GOx can be observed when GOx-PDA-rGO was immobilized on glassy carbon electrode (GCE). When glucose was added into the system, the modified electrode showed excellent electric current response toward glucose. These results inferred that the proposed multifunctional electrochemical platforms could be simply, conveniently, and effectively regulated through changing the anchored recognition or reaction groups. This study would provide a versatile method to design more detection or biosensing platforms through a chemical reaction strategy in the future. PMID:26222894

  3. Four-coordinate nickel(II) and copper(II) complex based ONO tridentate Schiff base ligands: synthesis, molecular structure, electrochemical, linear and nonlinear properties, and computational study.

    PubMed

    Novoa, Nstor; Roisnel, Thierry; Hamon, Paul; Kahlal, Samia; Manzur, Carolina; Ngo, Hoang Minh; Ledoux-Rak, Isabelle; Saillard, Jean-Yves; Carrillo, David; Hamon, Jean-Ren

    2015-11-01

    We report the synthesis, characterization, crystal structures, nonlinear-optical (NLO) properties, and density functional theory (DFT) calculations of nickel(ii) and copper(ii) complex based ONO tridentate Schiff base ligands: two mononuclear compounds, [Ni(An-ONO)(NC5H5)] (5) and [Cu(An-ONO)(4-NC5H4C(CH3)3)] (6), and two heterobimetallic species, [M(Fc-ONO)(NC5H5)] (M = Ni, 7; Cu, 8), where An-ONOH2 (3) and Fc-ONOH2 (4) are the 1?:?1 condensation products of 2-aminophenol and p-anisoylacetone and ferrocenoylacetone, respectively. These compounds were characterised by microanalysis, FT-IR and X-ray crystallography in the solid state and in solution by UV-vis and (1)H and (13)C NMR spectroscopy. The crystal structures of 3-5, 7 and 8 have been determined and show for Schiff base complexes 5, 7 and 8 a four-coordinated square-planar environment for nickel and copper ions. The electrochemical behavior of all derivatives 3-8 was investigated by cyclic voltammetry in dichloromethane, and discussed on the basis of DFT-computed electronic structures of the neutral and oxidized forms of the compounds. The second-order NLO responses of 3-8 have been determined by harmonic light scattering measurements using a 10(-2) M solution of dichloromethane and working with a 1.91 ?m incident wavelength, giving rather high ?1.91 values of 350 and 290 10(-30) esu for the mononuclear species 5 and 6, respectively. The assignment and the nature of the electronic transitions observed in the UV-vis spectra were analyzed using time-dependent (TD) DFT calculations. They are dominated by LMCT, MLCT and ?-?* transitions. PMID:26412689

  4. Mononuclear and tetranuclear compounds of yttrium and dysprosium ligated by a salicylic schiff-base derivative: synthesis, photoluminescence, and magnetism.

    PubMed

    Yadav, Munendra; Mereacre, Valeriu; Lebedkin, Sergei; Kappes, Manfred M; Powell, Annie K; Roesky, Peter W

    2015-02-01

    The Schiff-base (2-aminoethyl)hydroxybenzoic acid (H(2)L) as a proligand was prepared in situ from 3-formylsalicylic acid and ethanolamine (ETA). The mononuclear {[Y(HL)(4)][ETAH]H(2)O} (1) and {[Dy(HL)(4)] [ETAH]3MeOHH(2)O} (2) and tetranuclear {[Y(4)(HL)(2)(L)(4)(?(3)-OH)(2)]4MeOH4H(2)O} (3), {[Dy4(HL)(2)(L)(4)(?(3)-OH)(2)]5(MeOH)(2)7H(2)O (4), and {[Dy(4)(HL)(8)(L)(2)]4MeOH(2)H(2)O}(5) rare-earth metal complexes of this ligand could be obtained as single-crystalline materials by the treatment of H(2)L in the presence of the metal salts [Ln(NO(3))(3)(H(2)O)m] (Ln = Y, Dy). In the solid state, the tetranuclear compounds 3 and 4 exhibit butterfly structures, whereas 5 adopts a rectangular arrangement. Electrospray ionization mass spectrometry data of the ionic compounds 1 and 2 support single-crystal X-ray analysis. The yttrium compounds 1 and 3 show fluorescence with 11.5% and 13% quantum yield, respectively, whereas the quantum yield of the dysprosium complex 4 is low. Magnetic studies on the dysprosium compounds 4 and 5 suggest the presence of weak antiferromagnetic interactions between neighboring metal centers. Compound 4 shows single-molecule-magnet behavior with two relaxation processes, one with the effective energy barrier U(eff) = 84 K and the preexponential factor ?(0) = 5.1 10(-9) s. PMID:25238652

  5. Removal of uranium(VI) ions from aqueous solutions using Schiff base functionalized SBA-15 mesoporous silica materials.

    PubMed

    Dolatyari, Leila; Yaftian, Mohammad Reza; Rostamnia, Sadegh

    2016-03-15

    Functionalized SBA-15 mesoporous silica particles, bearing N-propylsalicylaldimine and ethylenediaminepropylesalicylaldimine Schiff base ligands, abbreviated as SBA/SA and SBA/EnSA respectively, were prepared and characterized by FT-IR, elemental analysis, TGA, XRD, TEM and SEM techniques. The potentials of these adsorbents were examined by using them in solid phase extraction of U(VI) ions from water samples. It is shown that 20 mg of SBA/SA or SBA/EnSA can remove rapidly (∼15 min) and quantitatively uranium(VI) ions from 10 to 200 mL of water solutions (pH 4) containing 0.2 mg of the ions, at 25 °C. The adsorbed ions were stripped by 1 mL of dilute nitric acid solution (0.1 mol L(-1)). It means that the studied adsorbents are able to be used for removal and concentration of uranyl ions. This allowed achieving to a concentration factor of 200 for uranyl ions. The variation in the ionic strength in the range 0-1 mol L(-1) did not affect the extraction efficiencies of the adsorbents. The adsorbents showed selective separation of uranyl ions from Cd(2+), Co(2+), Ni(2+), Mn(2+), Cr(3+), Ba(2+), Fe(3+) and Eu(3+) ions. Thermodynamic investigations revealed that the adsorption of uranyl ions by the adsorbents was spontaneous and endothermic. The Langmuir model described suitably the adsorption isotherms. This model determined the maximum adsorption capacity of the adsorbents SBA/SA and SBA/EnSA as 54 and 105.3 mg uranyl/g adsorbent, respectively. The kinetics of the processes was interpreted by using Pseudo-second-order model. PMID:26720327

  6. Spectral, electrochemical, thermal, DNA binding ability, antioxidant and antibacterial studies of novel Ru(III) Schiff base complexes.

    PubMed

    Abdel Aziz, Ayman A; Elbadawy, Hemmat A

    2014-04-24

    Four new air stable low spin Ru(III) complexes of the type [Ru(L(1-4))(H2O)2]Cl have been synthesized, where L=dianion of the tetradentate Schiff base ligands namely N,N'bis(salicylaldehyde)4,5-dimethy-l,2-phenylendiammine (L(1)H2), N,N'bis(salicylaldehyde)4,5-dichloro 1,2-phenylendiammine (L(2)H2), N,N'bis(o-vanillin)4,5-dimethy-1,2-phenylendiammine (L(3)H2) and N,N'bis(o-vanillin)4,5-dichloro-1,2-phenylendiammine (L(4)H2). The complexes have been fully characterized by elemental analysis, infrared spectroscopy, electronic spectroscopy, magnetic susceptibility and electron spin resonance spectroscopy. Elemental analyses and spectroscopic data have been showed that, the stoichiometries of complexes were 1:1 with an octahedral geometry for all the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. The redox behavior of the complexes has been investigated by the cyclic voltammetric technique. The interaction of these complexes with calf thymus DNA (CT-DNA) was explored by different techniques which revealed that the complexes could bind to CT-DNA through an intercalative mode. Furthermore, the antioxidant activity of the Ru(III) complexes against superoxide and hydroxyl radicals was evaluated by using spectrophotometer methods in vitro. The experiments on antioxidant activity show that the complexes were found to possess potent antioxidant activity. Additionally, as a potential application the antibacterial activity of the complexes was assessed by testing their effect on the growth of various strains of bacteria. PMID:24508879

  7. Vanadium(V) complex with Schiff-base ligand containing a flexible amino side chain: Synthesis, structure and reactivity.

    PubMed

    Nica, Simona; Rudolph, Manfred; Lippold, Ines; Buchholz, Axel; Görls, Helmar; Plass, Winfried

    2015-06-01

    The Schiff-base ligand (H2salhyhNH3)Cl (1) derived from salicylaldehyde and 6-aminohexanoic acid hydrazide hydrochloride reacts with ammonium metavanadate in methanol solution to yield the dioxidovanadium(V) complex [VO2(salhyhNH3)] (2). The utilized hydrazone ligand contains a flexible and protonated amino side chain. Crystallization from methanol affords complex 2 in the monoclinic space group P21/n, whereas crystallization from a methanol/water mixture 1:1 yields crystals, containing a water molecule of crystallization per two formula units (2⋅1/2H2O), in the orthorhombic space group Pbcn. In both cases the protonated amino group compensates the negative charge on the dioxidovanadium moiety and is involved in an extensive hydrogen bonding network particularly including the oxido groups from neighboring vanadium complexes. The reactivity of complex 2 toward protonation in aqueous solution has been investigated by spectrophotometric titrations and is characterized by two subsequent protonation steps at the hydrazide nitrogen atom of the ligand system and an oxido group leading to the formation of an oxidohydroxidovanadium(V) species with corresponding pKa values of 3.2 and 2.9, respectively. With larger excess of acid the oxidohydroxidovanadium(V) species starts to form the corresponding anhydride. The formation of the anhydride is strongly favored in the presence of methanol. The reaction of complex 2 with hydrogen peroxide in methanol solution leads to the formation of an oxidoperoxidovanadium(V) species, whereas in aqueous solution the addition of one equivalent of acid is required. Complex 2 catalyzes the oxidation of methylphenylsulfane to the corresponding sulfoxide in methanol/dichloromethane mixture using hydrogen peroxide as oxidant at room temperature. PMID:25747149

  8. A new structurally characterized organotin/Schiff-base complex with approximately rectangular molecular boxes formed through hydrogen bonds

    NASA Astrophysics Data System (ADS)

    Zhou, Yun-shan; Zhang, Li-juan; Zeng, Xi-rui; Vital, J. J.; You, Xiao-Zeng

    2000-10-01

    A new organotin/Schiff-base compound, C 24H 25Cl 4NO 3Sn0.5C 6H 6 ( 1), was prepared by the reaction of ?- n-butoxycarbonylethyltin trichlorides ( 2) with 2-hydroxy-1-naphthalideneaniline-4-Cl ( 3) in benzene, and characterized by single-crystal X-ray diffraction, IR, 1H NMR, and elemental analysis. Yellow rectangular rods of the title compound crystallize as a benzene solvate of formula C 24H 25Cl 4NO 3Sn0.5C 6H 6 ( 1) in the triclinic space group P-1. The unit cell has dimensions a=9.3624(2) , b=12.4947(3) , c=13.4821(3) , ?=70.7660(10), ?=87.1870(10), ?=75.1270(10), V=1438.13(6) 3, and Z=2. The structure was solved by direct method primarily and difmap secondarily. It is found that the OH hydrogen in free 2-hydroxy-1-naphthalideneaniline tautomerizes to the imine nitrogen due to the coordination of the phenolic oxygen atom with the Sn atom after the complex formation, while an intramolecular hydrogen bond still exists between O and N ( N⋯O=2.585(4) ). The Sn atom is coordinated with three chloride atoms, one carbon atom and two oxygen atoms, resulting in a distorted octahedra. The most notable feature of 1 lies in the ?-? interaction among the approximately planer 2-oxygen-1-naphthalideneaniline moieties and the rectangular molecular boxes formed through hydrogen bonds in which the benzene molecules reside.

  9. Synthesis, crystal structure, spectral characterization and photoluminescence property of three Cd(II) complexes with a pyrazole based Schiff-base ligand

    NASA Astrophysics Data System (ADS)

    Mandal, Susmita; Saha, Rajat; Saha, Manan; Pradhan, Rajesh; Butcher, Ray J.; Saha, Nitis Chandra

    2016-04-01

    Substituted pyrazole containing Schiff-base ligand, 5-methyl-3-formylpyrazole-N-(2‧-methylphenoxy)methyleneimine, (MPzOA), afforded three new Cd(II) complexes, [Cd(MPzOA)Cl2]2.CH3OH (I), [Cd(MPzOA)2(H2O)2](ClO4)2 (II) and [Cd(MPzOA)(H2O)(NO3)2] (III). In the reported complex species the coordination number and geometry of Cd(II) vary. In complex I and II, Cd(II) adopts six and in (III) it adopts eight coordination modes, with prismatic, octahedral and distorted dodecahedral geometry, respectively. All the complexes are characterized by IR, 1H NMR, UV-Vis spectral parameters and X-ray analyses. The complexes have 1D, 2D and 3D supramolecular frameworks formed by non-covalent interactions, like hydrogen bonding, π … π stacking, C-H … π interactions.

  10. Ligand Field Affected Single-Molecule Magnet Behavior of Lanthanide(III) Dinuclear Complexes with an 8-Hydroxyquinoline Schiff Base Derivative as Bridging Ligand.

    PubMed

    Wang, Wen-Min; Zhang, Hong-Xia; Wang, Shi-Yu; Shen, Hai-Yun; Gao, Hong-Ling; Cui, Jian-Zhong; Zhao, Bin

    2015-11-16

    New dinuclear lanthanide(III) complexes based on an 8-hydroxyquinoline Schiff base derivative and β-diketonate ligands, [Ln2(hfac)4(L)2] (Ln(III) = Gd (1), Tb (2), Dy (3), Ho (4), Er (5)), [Ln2(tfac)4(L)2] (Ln(III) = Gd (6), Tb (7), Dy (8), Ho (9)), and [Dy(bfac)4(L)2·C7H16] (10) (L = 2-[[(4-fluorophenyl)imino] methyl]-8-hydroxyquinoline, hfac = hexafluoroacetylacetonate, tfac = trifluoroacetylacetonate, and bfac = benzoyltrifluoroacetone), have been synthesized. The single-crystal X-ray diffraction data show that complexes 1-10 are phenoxo-O-bridged dinuclear complexes; each eight-coordinated center Ln(III) ion is in a slightly distorted dodecahedral geometry with two bidentate β-diketonate coligands and two μ2-O bridging 8-hydroxyquinoline Schiff base derivative ligands. The magnetic study reveals that 1 and 6 display cryogenic magnetic refrigeration properties, whereas complexes 3, 8, and 10 show different SMM behaviors with energy barriers of 6.77 K for 3, 19.83 K for 8, and 25.65 K for 10. Meanwhile, slow magnetic relaxation was observed in 7, while no out-of-phase alternating-current signals were found for 2. The different dynamic magnetic behaviors of two Tb2 complexes and the three Dy2 complexes mainly derive from the tiny crystal structure changes around the Ln(III) ions. It is also proved that the β-diketonate coligands can play an important role in modulating magnetic dynamics of the lanthanide 8-hydroxyquinoline Schiff base derivative system. PMID:26516660

  11. Synergistic therapeutic effects of Schiff's base cross-linked injectable hydrogels for local co-delivery of metformin and 5-fluorouracil in a mouse colon carcinoma model.

    PubMed

    Wu, Xilong; He, Chaoliang; Wu, Yundi; Chen, Xuesi

    2016-01-01

    In situ formed hydrogels based on Schiff base reaction were formulated for the co-delivery of metformin (ME) and 5-fluorouracil (5FU). The reactive aldehyde-functionalized four-arm polyethylene glycol (PFA) was synthesized by end-capping of 4-arm PEG with 4-formylbenzoic acid (FA) and used as a cross-linking agent. The injectable hydrogels are designed through the quick gelation induced by the formation of covalent bonds via Schiff-base reaction of PFA with 4-arm poly (ethylene glycol)-b-poly (L-lysine) (PPLL). This formulation eliminated the need for metal catalysts and complicated processes in the preparation of in situ-forming hydrogels. In vitro degradation and drug release studies demonstrated that both ME and 5FU were released through PFA/PPLL hydrogels in a controlled and pH-dependent manner. When incubated with mouse colon adenocarcinoma cells (C26), the ME/5FU-incorporated PFA/PPLL hydrogels had synergistic inhibitory effects on the cell cycle progression and cell proliferation in colon cancer cells. After a single subcutaneous injection of the hydrogel containing ME/5FU beside the tumors of BALB/c mice inoculated with C26 cells, the dual-drug-loaded hydrogels displayed superior therapeutic activity resulted from a combination of p53-mediated G1 arrest and apoptosis in C26 cells. Hence, the Schiff's base cross-linked hydrogels containing ME and 5FU may have potential therapeutic applications in the treatments of colon cancer. PMID:26497429

  12. Synthesis, spectral characterization, structural investigation and antimicrobial studies of mononuclear Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) complexes of a new potentially hexadentate N2O4 Schiff base ligand derived from salicylaldehyde

    NASA Astrophysics Data System (ADS)

    Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Elerman, Yalcin; Buyukgungor, Orhan

    2013-01-01

    A new potentially hexadentate N2O4 Schiff base ligand, H2L derived from condensation reaction of an aromatic diamine and salicylaldehyde, and its metal complexes were characterized by elemental analyses, IR, UV-Vis, EI-MS, 1H and 13C NMR spectra, as well as conductance measurements. It has been originated that the Schiff base ligand with Cu(II), Ni(II), Co(II), Cd(II) and Zn(II) ions form mononuclear complexes on 1:1 (metal:ligand) stoichiometry. The conductivity data confirm the non-electrolytic nature of the complexes. Also the crystal structures of the complexes [ZnL] and [CoL] have also been determined by using X-ray crystallographic technique. The Zn(II) and Co(II) complexes show a tetrahedral configuration. Electronic absorption spectra of the Cu(II) and Ni(II) complexes suggest a square-planar geometry around the central metal ion. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Bacillus cereus, Enterococcus faecalis and Listeria monocytogenes and also against the three Gram-negative bacteria: Salmonella paraB, Citrobacter freundii and Enterobacter aerogenes. The results showed that in some cases the antibacterial activity of complexes were more than nalidixic acid and amoxicillin as standards.

  13. Some new nano-structure zinc(II) coordination compounds of an imidazolidine Schiff base: spectral, thermal, antimicrobial properties and DNA interaction.

    PubMed

    Montazerozohori, Morteza; Musavi, Sayed Alireza; Naghiha, Asghar; Zohour, Mostafa Montazer

    2014-08-14

    Some novel nano-sized structure zinc complexes of a new Schiff base ligand entitled as (3-nitro-benzylidene)-{2-[2-(3-nitro-phenyl)-imidazolidine-1-yl]-ethyl}-amine(L) with general formula of ZnLX2 wherein X=Cl(-), Br(-), I(-), SCN(-) and N3(-) have been synthesized under ultrasonic conditions. The ligand and its complexes have been characterized by elemental analysis, molar conductance measurements, FT-IR, (1)H and (13)C NMR and UV-Visible spectroscopy. The resulting data from spectral investigation especially (1)H and (13)C NMR well confirmed formation of an imidazolidine ring in the ligand structure. Transmission electron microscopy (TEM) showed nano-size structures with average particle sizes of 21.80-78.10nm for the zinc(II) Schiff base complexes. The free Schiff base and its Zn(II) complexes have been screened in vitro both for antibacterial activity against some gram-positive and gram-negative bacteria and also for antifungal activity. The metal complexes were found to be more active than the free Schiff base ligand. The results showed that ZnL(N3)2 is the most effective inhibitor against Escherichia coli, Pseudomonas aereuguinosa, Staphylococcus aureus and Candida albicans while ZnLBr2 was found to be more effective against Bacillus subtillis than other compounds. Moreover, DNA cleavage potential of all compounds with plasmid DNA was investigated. The results showed that the ligand and ZnLCl2 complex cleave DNA more efficiently than others. In final, thermal analysis of ligand and its complexes revealed that they are decomposed via 2-3 thermal steps in the range of room temperature to 1000C. Furthermore some activation kinetic parameters such as A, E(*), ?H(*), ?S(*) and ?G(*) were calculated based on TG/DTA plots by use of coats - Redfern relation. Positive values of activation energy evaluated for the compounds confirmed the thermal stability of them. In addition to, the positive ?H(*), and ?G(*) values suggested endothermic character for the thermal decomposition steps. PMID:24747864

  14. Some new nano-structure zinc(II) coordination compounds of an imidazolidine Schiff base: Spectral, thermal, antimicrobial properties and DNA interaction

    NASA Astrophysics Data System (ADS)

    Montazerozohori, Morteza; Musavi, Sayed Alireza; Naghiha, Asghar; Zohour, Mostafa Montazer

    2014-08-01

    Some novel nano-sized structure zinc complexes of a new Schiff base ligand entitled as (3-nitro-benzylidene)-{2-[2-(3-nitro-phenyl)-imidazolidine-1-yl]-ethyl}-amine(L) with general formula of ZnLX2 wherein X = Cl-, Br-, I-, SCN- and N3- have been synthesized under ultrasonic conditions. The ligand and its complexes have been characterized by elemental analysis, molar conductance measurements, FT-IR, 1H and 13C NMR and UV-Visible spectroscopy. The resulting data from spectral investigation especially 1H and 13C NMR well confirmed formation of an imidazolidine ring in the ligand structure. Transmission electron microscopy (TEM) showed nano-size structures with average particle sizes of 21.80-78.10 nm for the zinc(II) Schiff base complexes. The free Schiff base and its Zn(II) complexes have been screened in vitro both for antibacterial activity against some gram-positive and gram-negative bacteria and also for antifungal activity. The metal complexes were found to be more active than the free Schiff base ligand. The results showed that ZnL(N3)2 is the most effective inhibitor against Escherichia coli, Pseudomonas aereuguinosa, Staphylococcus aureus and Candida albicans while ZnLBr2 was found to be more effective against Bacillus subtillis than other compounds. Moreover, DNA cleavage potential of all compounds with plasmid DNA was investigated. The results showed that the ligand and ZnLCl2 complex cleave DNA more efficiently than others. In final, thermal analysis of ligand and its complexes revealed that they are decomposed via 2-3 thermal steps in the range of room temperature to 1000 °C. Furthermore some activation kinetic parameters such as A, E*, ΔH*, ΔS* and ΔG* were calculated based on TG/DTA plots by use of coats - Redfern relation. Positive values of activation energy evaluated for the compounds confirmed the thermal stability of them. In addition to, the positive ΔH*, and ΔG* values suggested endothermic character for the thermal decomposition steps.

  15. Evidence for the involvement of more than one metal cation in the Schiff base deprotonation process during the photocycle of bacteriorhodopsin

    SciTech Connect

    Corcoran, T.C.; Ismail, K.Z.; El-Sayed, M.A.

    1987-06-01

    The removal of metal cations inhibits the deprotonation process of the protonated Schiff base during the photocycle of bacteriorhodopsin. To understand the nature of the involvement of these cations, a spectroscopic and kinetic study was carried out on bacteriorhodopsin samples in which the native Ca/sup 2 +/ and Mg/sup 2 +/ were replaced by Eu/sup 3 +/, a luminescent cation. The decay of Eu/sup 3 +/ emission in bacteriorhodopsin can be fitted to a minimum of three decay components, which are assigned to Eu/sup 3 +/ emission from three different sites. This is supported by the response of the decay components to the presence of /sup 2/H/sub 2/O and to the changes in the Eu/sup 3 +//bR molar ratio. The number of water molecules coordinated to Eu/sup 3 +/ in each site is determined from the change in its emission lifetime when /sup 2/H/sub 2/O replaces H/sub 2/O. Most of the emission originates from two wet sites of low crystal-field symmetry-e.g., surface sites. Protonated Schiff base deprotonation has no discernible effect on the emission decay of protein-bound Eu/sup 3 +/, suggesting an indirect involvement of metal cations in the deprotonation process. Adding Eu/sup 3 +/ to deionized bacteriorhodopsin increases the emission intensity of each Eu/sup 3 +/ site linearly, but the extent of the deprotonation (and color) changes sigmoidally. This suggests that if only the emitting Eu/sup 3 +/ ions cause the deprotonation and bacteriorhodopsin color change, ions in more than one site must be involved-e.g., by inducing protein conformation changes. The latter could allow deprotonation by the interaction between the protonated Schiff base and a positive field of cations either on the surface or within the protein.

  16. A series of transition and non-transition metal complexes from a N 4O 2 hexadentate Schiff base ligand: Synthesis, spectroscopic characterization and efficient antimicrobial activities

    NASA Astrophysics Data System (ADS)

    Sarkar, Saikat; Dey, Kamalendu

    2010-11-01

    Some transition and non-transition metal complexes of the hexadentate N 4O 2 donor Schiff base ligand 1,8- N-bis(3-carboxy)disalicylidene-3,6-diazaoctane-1,8-diamine, abbreviated to H 4fsatrien, have been synthesized. All the 14 metal complexes have been fully characterized with the help of elemental analyses, molecular weights, molar conductance values, magnetic moments and spectroscopic (UV-Vis, IR, NMR, ESR) data. The analytical data helped to elucidate the structures of the metal complexes. The Schiff base, H 4fsatrien, is found to act as a dibasic hexadentate ligand using N 2N 2O 2 donor set of atoms (leaving the COOH group uncoordinated) leading to an octahedral geometry for the complexes around all the metal ions except VO 2+ and UO 22+. However, surprisingly the same ligand functions as a neutral hexadentate and neutral tetradentate one towards UO 22+ and VO 2+, respectively. In case of divalent metal complexes they have the general formula [M(H 2fsatrien)] (where M stands for Cu, Co, Hg and Zn); for trivalent metal complexes it is [M(H 2fsatrien)]X· nH 2O (where M stands for Cr, Mn, Fe, Co and X stands for CH 3COO, Cl, NO 3, ClO 4) and for the complexes of VO 2+ and UO 22+, [M(H 4fsatrien)]Y (where M = VO and Y = SO 4; M = UO 2 and Y = 2 NO 3). The Schiff base ligand and most of the complexes have been screened in vitro to judge their antibacterial ( Escherichia coli and Staphylococcus aureus) and antifungal ( Aspergillus niger and Pencillium chrysogenum) activities.

  17. Synthesis, characterization, crystal structure and antimicrobial activity of copper(II) complexes with the Schiff base derived from 2-hydroxy-4-methoxybenzaldehyde.

    PubMed

    Pahon?u, Elena; Ilie?, Diana-Carolina; Shova, Sergiu; Paraschivescu, Codru?a; Badea, Mihaela; Gulea, Aurelian; Ro?u, Tudor

    2015-01-01

    A novel Schiff base, ethyl 4-[(E)-(2-hydroxy-4-methoxyphenyl)methylene-amino]benzoate (HL), was prepared and structurally characterized on the basis of elemental analyses, (1)H NMR, (13)C NMR, UV-Vis and IR spectral data. Six new copper(II) complexes, [Cu(L)(NO3)(H2O)2] (1), [Cu(L)2] (2), [Cu(L)(OAc)] (3), [Cu2 (L)2Cl2(H2O)4] (4), [Cu(L)(ClO4)(H2O)] (5) and [Cu2(L2S)(ClO4)(H2O)]ClO4H2O (6) have been synthesized. The characterization of the newly formed compounds was done by IR, UV-Vis, EPR, FAB mass spectroscopy, elemental and thermal analysis, magnetic susceptibility measurements and molar electric conductivity. The crystal structures of Schiff base and the complex [Cu2(L2S)(ClO4)(H2O)]ClO4H2O (6) have been determined by single crystal X-ray diffraction studies. Both copper atoms display a distorted octahedral coordination type [O4NS]. This coordination is ensured by three phenol oxygen, two of which being related to the -oxo-bridge, the nitrogen atoms of the azomethine group and the sulfur atoms that come from the polydentate ligand. The in vitro antimicrobial activity against Escherichia coli ATCC 25922, Salmonella enteritidis, Staphylococcus aureus ATCC 25923, Enterococcus and Candida albicans strains was studied and compared with that of free ligand. The complexes 1, 2, 5 showed a better antimicrobial activity than the Schiff base against the tested microorganisms. PMID:25849802

  18. Design, characterization, teratogenicity testing, antibacterial, antifungal and DNA interaction of few high spin Fe(II) Schiff base amino acid complexes

    NASA Astrophysics Data System (ADS)

    Abdel-Rahman, Laila H.; El-Khatib, Rafat M.; Nassr, Lobna A. E.; Abu-Dief, Ahmed M.; Lashin, Fakhr El-Din

    2013-07-01

    In this study, new Fe(II) Schiff base amino acid chelates derived from the condensation of o-hydroxynaphthaldehyde with L-alanine, L-phenylalanine, L-aspartic acid, L-histidine and L-arginine were synthesized and characterized via elemental, thermogravimetric analysis, molar conductance, IR, electronic, mass spectra and magnetic moment measurements. The stoichiometry and the stability constants of the complexes were determined spectrophotometrically. Correlation of all spectroscopic data suggested that Schiff bases ligands exhibited tridentate with ONO sites coordinating to the metal ions via protonated phenolic-OH, azomethine-N and carboxylate-O with the general formulae [Fe(HL)2]·nH2O. But in case of L-histidine, the ligand acts as tetradentate via deprotonated phenolic-OH, azomethine-N, carboxylate-O and N-imidazole ring ([FeL(H2O)2]·2H2O), where HL = mono anion and L = dianion of the ligand. The structure of the prepared complexes is suggested to be octahedral. The prepared complexes were tested for their teratogenicity on chick embryos and found to be safe until a concentration of 100 μg/egg with full embryos formation. Moreover, the interaction between CT-DNA and the investigated complexes were followed by spectrophotometric and viscosity measurements. It was found that, the prepared complexes bind to DNA via classical intercalative mode and showed a different DNA activity with the sequence: nhi > nari > nali > nasi > nphali. Furthermore, the free ligands and their complexes are screened for their in vitro antibacterial and antifungal activity against three types of bacteria, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus and three types of anti fungal cultures, Penicillium purpurogenium, Aspergillus flavus and Trichotheium rosium in order to assess their antimicrobial potential. The results show that the metal complexes are more reactive with respect to their corresponding Schiff base amino acid ligands.

  19. Design, characterization, teratogenicity testing, antibacterial, antifungal and DNA interaction of few high spin Fe(II) Schiff base amino acid complexes.

    PubMed

    Abdel-Rahman, Laila H; El-Khatib, Rafat M; Nassr, Lobna A E; Abu-Dief, Ahmed M; Lashin, Fakhr El-Din

    2013-07-01

    In this study, new Fe(II) Schiff base amino acid chelates derived from the condensation of o-hydroxynaphthaldehyde with L-alanine, L-phenylalanine, L-aspartic acid, L-histidine and L-arginine were synthesized and characterized via elemental, thermogravimetric analysis, molar conductance, IR, electronic, mass spectra and magnetic moment measurements. The stoichiometry and the stability constants of the complexes were determined spectrophotometrically. Correlation of all spectroscopic data suggested that Schiff bases ligands exhibited tridentate with ONO sites coordinating to the metal ions via protonated phenolic-OH, azomethine-N and carboxylate-O with the general formulae [Fe(HL)2]nH2O. But in case of L-histidine, the ligand acts as tetradentate via deprotonated phenolic-OH, azomethine-N, carboxylate-O and N-imidazole ring ([FeL(H2O)2]2H2O), where HL=mono anion and L=dianion of the ligand. The structure of the prepared complexes is suggested to be octahedral. The prepared complexes were tested for their teratogenicity on chick embryos and found to be safe until a concentration of 100 ?g/egg with full embryos formation. Moreover, the interaction between CT-DNA and the investigated complexes were followed by spectrophotometric and viscosity measurements. It was found that, the prepared complexes bind to DNA via classical intercalative mode and showed a different DNA activity with the sequence: nhi>nari>nali>nasi>nphali. Furthermore, the free ligands and their complexes are screened for their in vitro antibacterial and antifungal activity against three types of bacteria, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus and three types of anti fungal cultures, Penicillium purpurogenium, Aspergillus flavus and Trichotheium rosium in order to assess their antimicrobial potential. The results show that the metal complexes are more reactive with respect to their corresponding Schiff base amino acid ligands. PMID:23665616

  20. Amino alcohol-derived reduced Schiff base V(IV)O and V(V) compounds as catalysts for asymmetric sulfoxidation of thioanisole with hydrogen peroxide.

    PubMed

    Ado, Pedro; Kuznetsov, Maxim L; Barroso, Snia; Martins, Ana M; Avecilla, F; Costa Pessoa, Joo

    2012-11-01

    We report the synthesis and characterization of several amino alcohol-derived reduced Schiff base ligands (AORSB) and the corresponding V(IV)O and V(V) complexes. Some of the related Schiff base variants (amino alcohol derived Schiff base = AOSB) were also prepared and characterized. With some exceptions, all compounds are formulated as dinuclear compounds {V(IV)O(L)}(2) in the solid state. Suitable crystals for X-ray diffraction were obtained for two of the AORSB compounds, as well as a rare X-ray structure of a chiral V(IV)O compound, which revealed a dinuclear {V(IV)O(AOSB)}(2) structure with a rather short V-V distance of 3.053(9) . Electron paramagnetic resonance (EPR), (51)V NMR, and density functional theory (DFT) studies were carried out to identify the intervenient species prior to and during catalytic reactions. The quantum-chemical DFT calculations were important to determine the more stable isomers in solution, to explain the EPR data, and to assign the (51)V NMR chemical shifts. The V(AORSB) and V(AOSB) complexes were tested as catalysts in the oxidation of thioanisole, with H(2)O(2) as the oxidant in organic solvents. In general, high conversions of sulfoxide were obtained. The V(AOSB) systems exhibited greater activity and enantioselectivity than their V(AORSB) counterparts. Computational and spectroscopic studies were carried out to assist in the understanding of the mechanistic aspects and the reasons behind such marked differences in activity and enantioselectivity. The quantum-chemical calculations are consistent with experimental data in the assessment of the differences in catalytic activity between V(AOSB) and V(AORSB) peroxido variants because the V(AORSB) peroxido transition states correspond to ca. 22 kJ/mol higher energy activation barriers than their V(AOSB) counterparts. PMID:23092396

  1. Keto-enol tautomerism of two structurally related Schiff bases: Direct and indirect way of creation of the excited keto tautomer

    NASA Astrophysics Data System (ADS)

    Fita, P.; Luzina, E.; Dziembowska, T.; Kope?, D.; Pi?tkowski, P.; Radzewicz, Cz.; Grabowska, A.

    2005-12-01

    Femtosecond time-resolved absorption spectra of two structurally related, internally H-bonded Schiff bases are reported. The 2-hydroxynaphthylidene-1'-naphthylamine (HNAN) stable as an enol tautomer undergoes an ultrafast excited state intramolecular proton transfer, while the 2-hydroxynaphthylidene-(8'-aminoquinoline) (HNAQ), stable as a keto structure, reveals unusual relaxation routes after electronic excitation. In particular, the rise of the bleaching band with the characteristic time of 700 fs was found and attributed to a gradual population of the S 1 fluorescent state from a 'hot' excited state. The results accompanied by TDDFT calculations are used to construct the diagram of relaxation routes of an excited HNAQ molecule.

  2. Synthesis, spectroscopic characterization and antimicrobial activity of binuclear metal complexes of a new asymmetrical Schiff base ligand: DNA binding affinity of copper(II) complexes.

    PubMed

    Shebl, Magdy

    2014-01-01

    The 1:1 condensation of o-acetoacetylphenol and 1,2-diaminopropane under condition of high dilution gives the mono-condensed Schiff base, (E)-3-(1-aminopropan-2-ylimino)-1-(2-hydroxyphenyl)butan-1-one. The mono-condensed Schiff base has been used for further condensation with isatin to obtain the new asymmetrical dicompartmental Schiff base ligand, (E)-3-(2-((E)-4-(2-hydroxyphenyl)-4-oxobutan-2-ylideneamino) propylimino)indolin-2-one (H3L) with a N2O3 donor set. Reactions of the ligand with metal salts give a series of new binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, (1)H and (13)C NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. The analytical and spectroscopic tools showed that the complexes can be formulated as: [(HL)(VO)2(SO4)(H2O)]4H2O, [(HL)Fe2Cl4(H2O)3]EtOH, [(HL)Fe2(ox)Cl2(H2O)3]2H2O, [(L)M2(OAc)(H2O)m]nH2O; M=Co, Ni or Cu, m=4, 0 and n=2, 3, [(HL)Cu2Cl]Cl6H2O and [(L)(UO2)2(OAc)(H2O)3]6H2O. The metal complexes exhibited octahedral geometrical arrangements except copper complexes that exhibited tetrahedral geometries and uranyl complex in which the metal ion is octa-coordinated. The Schiff base and its metal complexes were evaluated for antimicrobial activity against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli) and fungi (Candida albicans and Aspergillus flavus). The ligand and some of its complexes were found to be biologically active. The DNA-binding properties of the copper complexes (6 and 7) have been investigated by electronic absorption, fluorescence and viscosity measurements. The results obtained indicate that these complexes bind to DNA via an intercalation binding mode with an intrinsic binding constant, Kb of 1.3410(4) and 2.510(4) M(-1), respectively. PMID:23988527

  3. Nanomolar fluorogenic detection of Al(III) by a series of Schiff bases in an aqueous system and their application in cell imaging.

    PubMed

    Sharma, Sanyog; Hundal, Maninder Singh; Walia, Amandeep; Vanita, Vanita; Hundal, Geeta

    2014-07-01

    Three positional isomers of a Schiff base containing -OH as end groups have been synthesized and evaluated for selective Al(III) detection due to inhibition of ESIPT, PET and activation of CHEF in 70% aqueous medium. Devoid of any conventional fluorophore, these sensors have nanomolar detection limits with high quantum yields and naked eye sensing of Al(III). Moreover, these probes have been demonstrated to enable the Al(III) detection in live human HeLa cells and rat C6 glioma cells using a confocal microscope. PMID:24849460

  4. Synthesis, spectroscopic characterization and antimicrobial activity of binuclear metal complexes of a new asymmetrical Schiff base ligand: DNA binding affinity of copper(II) complexes

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy

    2014-01-01

    The 1:1 condensation of o-acetoacetylphenol and 1,2-diaminopropane under condition of high dilution gives the mono-condensed Schiff base, (E)-3-(1-aminopropan-2-ylimino)-1-(2-hydroxyphenyl)butan-1-one. The mono-condensed Schiff base has been used for further condensation with isatin to obtain the new asymmetrical dicompartmental Schiff base ligand, (E)-3-(2-((E)-4-(2-hydroxyphenyl)-4-oxobutan-2-ylideneamino) propylimino)indolin-2-one (H3L) with a N2O3 donor set. Reactions of the ligand with metal salts give a series of new binuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, 1H and 13C NMR, electronic, ESR and mass spectra, conductivity and magnetic susceptibility measurements as well as thermal analyses. The analytical and spectroscopic tools showed that the complexes can be formulated as: [(HL)(VO)2(SO4)(H2O)]·4H2O, [(HL)Fe2Cl4(H2O)3]·EtOH, [(HL)Fe2(ox)Cl2(H2O)3]·2H2O, [(L)M2(OAc)(H2O)m]·nH2O; M = Co, Ni or Cu, m = 4, 0 and n = 2, 3, [(HL)Cu2Cl]Cl·6H2O and [(L)(UO2)2(OAc)(H2O)3]·6H2O. The metal complexes exhibited octahedral geometrical arrangements except copper complexes that exhibited tetrahedral geometries and uranyl complex in which the metal ion is octa-coordinated. The Schiff base and its metal complexes were evaluated for antimicrobial activity against Gram positive bacteria (Staphylococcus aureus), Gram negative bacteria (Escherichia coli) and fungi (Candida albicans and Aspergillus flavus). The ligand and some of its complexes were found to be biologically active. The DNA-binding properties of the copper complexes (6 and 7) have been investigated by electronic absorption, fluorescence and viscosity measurements. The results obtained indicate that these complexes bind to DNA via an intercalation binding mode with an intrinsic binding constant, Kb of 1.34 × 104 and 2.5 × 104 M-1, respectively.

  5. New tetradentate Schiff bases of 2-amino-3,5-dibromobenzaldehyde with aliphatic diamines and their metal complexes: synthesis, characterization and thermal stability.

    PubMed

    Mohammadi, Khosro; Azad, Seyyedeh Sedigheh; Amoozegar, Ameneh

    2015-07-01

    The tetradentate Schiff base ligands (L(1)-L(4)), were synthesized by reaction between 2-amino-3,5-dibromobenzaldehyde and aliphatic diamines. Then, nickel and oxovanadium(IV) complexes of these ligands were synthesized and characterized by (1)H NMR, Mass, IR, UV-Vis spectroscopy and thermogravimetry. The kinetic parameters of oxovanadium(IV) complexes were calculated from thermal studies. According to the results of thermogravimetric data, the thermal stability of oxovanadium(IV) complexes is as follow: [Formula: see text]. PMID:25813179

  6. Infrared and DNA-binding on ultraviolet and fluorescence spectra of new copper and zinc complexes with a naringenin Schiff-base ligand

    NASA Astrophysics Data System (ADS)

    Li, Yan-hua; Wang, Bao-dui; Yang, Zheng-yin

    2007-06-01

    A naringenin Schiff-base ligand (H 3L) and its copper(II) and zinc(II) complexes have been synthesized and characterized by elemental analyses, molar conductivities, 1H NMR, IR spectra, UV spectra and thermal analyses. The DNA-binding properties of the Cu(II) and Zn(II) complexes have been investigated by fluorescence spectroscopy, ultraviolet spectroscopy and by viscosity measurements. The results indicate that complexes and ligand may bind to DNA by intercalation modes, but the binding affinity of the complexes is much higher than that of the ligand.

  7. Synthesis of novel p-tert-butylcalix[4]arene Schiff bases and their complexes with C60, potential HIV-Protease inhibitors

    NASA Astrophysics Data System (ADS)

    Khadra, Khalid Abu; Mizyed, Shehadeh; Marji, Deeb; Haddad, Salim F.; Ashram, Muhammad; Foudeh, Ayat

    2015-02-01

    Some p-tert-butylcalix[4]arene Schiff base crown ethers were synthesized, characterized using 1H, 13C-NMR, DEPT 135 and Mass spectrometry. Their complexes with C60 were isolated and characterized. The inhibition effect of these complexes on HIVP was studied and found that complexes of 9 and 10 have comparable Ki values to Pepstatine which is known as HIVP inhibitor and used as a control. The synthesis of the ligands, complexes and the inhibition behavior are discussed in this article.

  8. ?g: The new aromaticity index based on g-factor calculation applied for polycyclic benzene rings

    NASA Astrophysics Data System (ADS)

    Ucun, Fatih; Tokatl?, Ahmet

    2015-02-01

    In this work, the aromaticity of polycyclic benzene rings was evaluated by the calculation of g-factor for a hydrogen placed perpendicularly at geometrical center of related ring plane at a distance of 1.2 . The results have compared with the other commonly used aromatic indices, such as HOMA, NICSs, PDI, FLU, MCI, CTED and, generally been found to be in agreement with them. So, it was proposed that the calculation of the average g-factor as ?g could be applied to study the aromaticity of polycyclic benzene rings without any restriction in the number of benzene rings as a new magnetic-based aromaticity index.

  9. Metal complexes of Schiff base derived from sulphametrole and o-vanilin . Synthesis, spectral, thermal characterization and biological activity

    NASA Astrophysics Data System (ADS)

    Mohamed, Gehad G.; Sharaby, Carmen M.

    2007-04-01

    Metal complexes of Schiff base derived from condensation of o-vanilin (3-methoxysalicylaldehyde) and sulfametrole [ N1-(4-methoxy-1,2,5-thiadiazole-3-yl)sulfanilamide] (H 2L) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, mass spectra, UV-vis and thermal analysis (TGA). From the elemental analyses data, the complexes were proposed to have the general formulae [M 2X 3(HL)(H 2O) 5]· yH 2O (where M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), X = Cl, y = 0-3); [Fe 2Cl 5(HL)(H 2O) 3]·2H 2O; [(FeSO 4) 2(H 2L)(H 2O) 4] and [(UO 2) 2(NO 3) 3(HL)(H 2O)]·2H 2O. The molar conductance data reveal that all the metal chelates were non-electrolytes. The IR spectra show that, H 2L is coordinated to the metal ions in a tetradentate manner with ON and NO donor sites of the azomethine-N, phenolic-OH, enolic sulphonamide-OH and thiadiazole-N. From the magnetic and solid reflectance spectra, it is found that the geometrical structures of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, Δ H*, Δ S* and Δ G* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligand, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Salmonella typhi, Bacillus subtillus, Staphylococcus aureus and Fungi ( Aspergillus terreus and Aspergillus flavus). The activity data show that the metal complexes to be more potent/antimicrobial than the parent Shciff base ligand against one or more microbial species.

  10. Auxiliary Ligand-Dependent Assembly of Several Ni/Ni-Cd Compounds with N2O2 Donor Tetradentate Symmetrical Schiff Base Ligand

    SciTech Connect

    Ge, Ying Ying; Li, Guo-Bi; Fang, Hua-Cai; Zhan, Xu Lin; Gu, Zhi-Gang; Chen, Jin Hao; Sun, Feng; Cai, Yue-Peng; Thallapally, Praveen K.

    2010-09-18

    Several low-dimensional Ni/Ni-Cd complexes containing N2O2 donor tetradentate symmetrical Schiff base ligand bis(acetylacetone)ethylene-diamine (sy-H2L2), namely, [Ni(sy-L2)]2?HLa?ClO4 (2), (HLa)2?(ClO4)?(NO3) (3), [Ni(sy-L2)X]2](4,4-bipy) (where La = 5,7-dimethyl-3,6-dihydro-2H-1,4-diazepine, X = ClO4 (4), X=NO3 (5), [Ni(sy-L2)Cd(SCN)2]n (6) and [Ni(sy-L2)?Cd(N3)2]n (7) have been synthesized from [Ni(sy-L2)]2?H2O (1). Complex 2, is three component discrete assembly generated from (HLa)+ moiety bridged with [Ni(sy-L2)] unit and ClO4- anion. A solution containing complex 2 and Cd(NO3)2 results in a mixture of 1 and 3. Further re-crystallization of 1 and 3 with various auxiliary ligands, provides coordination complexes 4 7 stabilized by weak hydrogen bonds in which 6 and 7 represent the first 1D heteronuclear complexes based on symmetric acacen-base Schiff base ligand.

  11. Magnetic Beads-based Bioelectrochemical Immunoassay of Polycyclic Aromatic Hydrocarbons

    SciTech Connect

    Lin, Ying-Ying; Liu, Guodong; Wai, Chien M.; Lin, Yuehe

    2007-07-01

    A simple, rapid, and sensitive bioelectrochemical immunoassay method based on magnetic beads (MBs) has been developed to detect polycyclic aromatic hydrocarbons (PAHs). The principle of this bioassay is based on a direct competitive enzyme-linked immunosorbent assay using PAH-antibody-coated MBs and horseradish peroxidase (HRP)-labeled PAH (HRP-PAH). A magnetic process platform was used to mix and shake the samples during the immunoreactions and to separate free and unbound reagents after the liquid-phase competitive immunoreaction among PAH-antibody-coated MBs, PAH analyte, and HRP-PAH. After a complete immunoassay, the HRP tracers attached to MBs were transferred to a substrate solution containing 3, 3, 5, 5- tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2) for electrochemical detection. The voltammetric characteristics of the substrate were investigated, and the reduction peak current of TMB was used to quantify the concentration of PAH. The different parameters, including the amount of HRP-PAH conjugates, the enzyme catalytic reaction time, and the pH of the supporting electrolyte that governs the analytical performance of the immunoassay have been studied in detail and optimized. The detection limit of 50 pg mL-1 was obtained under optimum experimental conditions. The performance of this bioelectrochemical magnetic immunoassay was successfully evaluated with tap water spiked with PAHs, indicating that this convenient and sensitive technique offers great promise for decentralized environmental applications.

  12. Synthesis, spectroscopic characterization and antimicrobial studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with Schiff bases derived from 5-bromo-salicylaldehyde

    NASA Astrophysics Data System (ADS)

    Kursunlu, Ahmed Nuri; Guler, Ersin; Sevgi, Fatih; Ozkalp, Birol

    2013-09-01

    In this study, the new Schiff base ligands derived from condensation of amine and 5-bromo-salicylaldehyde were characterized. All compounds, the Schiff bases and the metal complexes, were characterized by elemental analyzes, FT-IR, 1H NMR, 13C NMR and magnetic susceptibility measurements. The synthesized ligands, along with their metal (II) complexes, were screened for their in vitro antibacterial activity against four Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Salmonella enteritidis) and four Gram-positive (Streptococcus pyogones, Bacillus cereus, Staphylococcus aureus and Methicillin-resistant S. aureus) bacterial strains by using disc diffusion and broth microdilution techniques.

  13. Synthesis of a series of new platinum organometallic complexes derived from bidentate Schiff-base ligands and their catalytic activity in the hydrosilylation and dehydrosilylation of styrene.

    PubMed

    Lachachi, M Belhadj; Benabdallah, Tayeb; Aguiar, Pedro M; Youcef, M Hadj; Whitwood, Adrian C; Lynam, Jason M

    2015-07-14

    The synthesis and properties of a novel class of platinum complexes containing Schiff bases as O,N-bidentate ligands is described as are the solution and solid state properties of the uncomplexed ligands. The platinum complexes were prepared from [PtBr2(COD)] (COD = 1,5-cyclooctadiene) and N-(2-hydroxy-1-naphthalidene)aniline derivatives in the presence of base (NaOBu(t)). Instead of a substitution reaction to afford cationic species, the addition of the Schiff base ligands results in both the formal loss of two equivalents of bromide and addition of hydroxide to the COD ligand of the complexes. It is proposed that this reaction proceeds through a cationic platinum complex [Pt(N-O)(COD)]Br which then undergoes addition of water and loss of HBr. An example of a dinuclear platinum complex in which two cyclo-octene ligands are bridged by an ether linkage is also reported. The platinum complexes were evaluated as catalysts for the hydrogenative and dehydrogenative silylation of styrene, the resulting behaviour is substituent, time and temperature dependent. PMID:26061657

  14. Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: synthesis, characterization, fluorescence and corrosion inhibitors of ligands.

    PubMed

    Ali, Omyma A M

    2014-11-11

    Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2·H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans. PMID:24858346

  15. Palladium(II) and zinc(II) complexes of neutral [N2O2] donor Schiff bases derived from furfuraldehyde: Synthesis, characterization, fluorescence and corrosion inhibitors of ligands

    NASA Astrophysics Data System (ADS)

    Ali, Omyma A. M.

    2014-11-01

    Metal complexes of Schiff bases derived from furfuraldehyde and 4,5-dimethyl-1,2-phenylendiamine (L1) or 4,5-dichloro-1,2-phenylendiamine (L2) have been reported and characterized based on elemental analyses, IR, 1H NMR, UV-Vis, magnetic moment, molar conductance and thermal analysis. The complexes are found to have the formulae [PdL1-2]Cl2 and [ZnL1-2](AcO)2·H2O. The molar conductance data reveal that Pd(II) and Zn(II) chelates are ionic in nature and are of the type 2:1 electrolytes. The spectral data are consistent with a square planar and tetrahedral geometry around Pd(II) and Zn(II), respectively, in which the ligands act as tetradentate ligands. The thermal behavior of some chelates is studied and the activation thermodynamic parameters are calculated using Coats-Redfern method. The corrosion inhibition of stainless steel types 410 and 304 in 1 M HCl using the synthesized Schiff bases as inhibitors have been studied by weight loss method. The obtained data considered these ligands as efficient corrosion inhibitors. The ligands and their metal complexes exhibited considerable antibacterial activity against Staphylococcusaureus, and Escherichiacoli and antifungal activity against Candida albicans.

  16. Development of a force field for some copper(II) Schiff-base complexes

    NASA Astrophysics Data System (ADS)

    Subramanian, V.; Shankaranarayanan, C.; Nair, Balachandran Unni; Kanthimathi, M.; Manickkavachagam, R.; Ramasami, T.

    1997-08-01

    Molecular mechanics calculations have been performed on Cu(N,N'-ethylenebis(salicylideneimine)) [ Cu( salen)], Cu(N,N'-propylenebis(salicylideneimine)) [ Cu( salprn)] and Cu(N,N'-butylenebis(salicylideneimine)) [ Cu( salbuen)] after generating a well-balanced force field based on the structural parameters available for Cu(salen) and Cu(salprn). The optimized stretching force constant for Cu?N and Cu?O bond types is 2.25 mdyn/ and the bending force constant corresponding to N?Cu?N, O?Cu?O and O?Cu?N types is 0.5 mdyn/. The stability and structural parameters have been predicted based on the calculations.

  17. Experimental and Theoretical Investigations of Magnetic Exchange Pathways in Structurally Diverse Iron(III) Schiff-Base Complexes.

    PubMed

    Herchel, Radovan; Nemec, Ivan; Machata, Marek; Trávníček, Zdeněk

    2015-09-01

    The synthesis, and the structural and magnetic properties, of the following new iron(III) Schiff base complexes with the {O',N,O″}-chelating ligand H2L (2-hydroxyphenylsalicylaldimine) are reported: K[FeL2]·H2O (1), (Pr3NH)[FeL2]·2CH3OH (2), [FeL(bpyO2) (CH3OH)][FeL2]·CH3OH (3), [Fe2L3(CH3OH)]·2CH3OH·H2O (4), and [{Fe2L2}(μ-OH)2{FeL(bpyO2)}2][BPh4]2·2H2O (5), where Pr3NH(+) represents the tripropylammonium cation and bpyO2 stands for 2,2'-bipyridine-N-dioxide. A thorough density functional theory (DFT) study of magnetic interactions (the isotropic exchange) at the B3LYP/def-TZVP level of theory was employed, and calculations have revealed superexchange pathways through intramolecular/intermolecular noncovalent contacts (π-π stacking, C-H···O and O-H···O hydrogen bonds, diamagnetic metal cations) and/or covalent bonds ((μ-O(Ph), μ-OH) or bis(μ-O(Ph)) bridging modes), which helped us to postulate trustworthy spin Hamiltonians for magnetic analysis of experimental data. Within the reported family of compounds 1-5, the mediators of the antiferromagnetic exchange can be sorted by their increasing strength as follows: π-π stacking (J(DFT) = -0.022 cm(-1)/J(mag) = -0.025(4) cm(-1) in 2) < C-H···O contacts and π-π stacking (J(DFT) = -0.19 cm(-1)/J(mag) = -0.347(9)cm(-1) in 1) < O-H···O hydrogen bonds (J(DFT) = -0.53 cm(-1)/J(mag) = -0.41(1) cm(-1) in 3) < bis(μ-O(Ph)) bridge (J(DFT) = -13.8 cm(-1)/J(mag) = -12.3(9) cm(-1) in 4) < (μ-O(Ph), μ-OH) bridge (J(DFT) = -18.0 cm(-1)/J(mag) = -17.1(2) cm(-1) in 5), where J(DFT) and J(mag) are the isotropic exchange parameters derived from DFT calculations, and analysis of the experimental magnetic data, respectively. The good agreement between theoretically calculated and experimentally derived isotropic exchange parameters suggests that this procedure is applicable also for other chemical and structural systems to interpret magnetic data properly. PMID:26262499

  18. Chromo/Fluorogenic Detection of Co(2+), Hg(2+) and Cu(2+) by the Simple Schiff Base Sensor.

    PubMed

    Saleem, Muhammad; Khang, Chung Ho; Kim, Moon-Hwan; Lee, Ki Hwan

    2016-01-01

    Herein, we reported the ditriazole Schiff base derivative 1 and evaluated its photophysical properties on induction of varieties of metal ions including Na(+), Ag(+), Ni(2+), Mn(2+), Pd(2+), Co(2+), Hg(2+), Cu(2+), Pb(2+), Cd(2+), Zn(2+), Sn(2+), Fe(2+), Fe(3+), Cr(3+) and Al(3+), in order to figure out its potential as ion sensor. The ligand 1 exhibited the strong colorimetric change in the reaction solution as well as absorption spectral shifting with the concomitant appearance of well-defined isosbestic points only upon Co(2+), Hg(2+) and Cu(2+) addition corroborates its applicability as multichannel ion detector. The different extent of spectral shifting as well as unique chromogenic change in the probe solution upon Co(2+), Hg(2+) and Cu(2+) introduction can be used as the discrimination tool for these metal ions. The ligand-metal binding stoichiometry was assessed by their optical response which was further supported by the FT-IR, NMR and mass spectrometric analysis. The association constant and the detection limits of the ligand toward Co(2+), Hg(2+) and Cu(2+) ions were calculated to be 1.52 × 10(-8), 3.26 × 10(-9), 1.16 × 10(-8) and 3.87 × 10(-10), 5.47 × 10(-11), 8.91 × 10(-11) M, respectively, employing the Benesi-Hilderbrand equation and 3 σ slope(-1) methods. Furthermore, the successive addition of Co(2+), Hg(2+) and Cu(2+) induce the constant decline in the fluorescence emission signal intensity of the probe. The quenching efficiency of the probe upon metallic induction was fitted to the Stern-Volmer equation which yielded the upward curvature in case of all the three metals ions (Co(2+), Hg(2+) and Cu(2+)) when (Io/I-1) was plotted against the quencher concentration indicating the occurrence of both the dynamic and static quenching process in the system with the average Stern-Volmer quenching constant values of 9.25 × 10(-7), 1.14 × 10(-7), 1.829 × 10(-7), respectively. PMID:26585349

  19. Conservation of Helicity in a Chiral Pyrrol-2-yl Schiff-Base Ligand and Its Transition Metal Complexes.

    PubMed

    Dezhahang, Zahra; Poopari, Mohammad Reza; Cheramy, Joseph; Xu, Yunjie

    2015-05-01

    Tetradentate enantiopure Schiff-base ligand (R,R) and (S,S)-bis(pyrrol-2-ylmethyleneamine)-cyclohexane (H2L) and its five transition metal complexes with Ni(II), Cu(II), Zn(II), Pd(II), and Pt(II) were synthesized. Their structural properties, in particular, the ligand chirality, coordination topology, and the resulting helicity in solution, were investigated by using IR, vibrational circular dichroism (VCD), UV-vis, and electronic circular dichroism (ECD) spectroscopies, complemented with density functional theory calculations. Conformational searches and the associated spectral simulations for the ligands and the complexes were performed at the B3LYP/Gen level. Comparison of the experimental and theoretical IR and VCD spectral signatures of these complexes reveal that the Zn complex takes on a dinuclear, distorted tetrahedral coordination topology around the metal centers, whereas the other four metal complexes adopt the mononuclear, distorted square-planar coordination arrangement in solution. The helicity of all systems studied was identified to be M with the (R,R) ligand and P with the (S,S) ligand, dictated by the ligand chirality and the strong preference for the chair configuration by the cyclohexane moiety. Furthermore, the resulting helicity was found to dominate the ECD spectral features, even though the helicity-determining angles are close to zero for the nearly square-planar metal complexes. The related VCD spectral features are sensitive to both helicity of the complex and the chirality of the ligands, as well as the coordination topology. The simulated ECD spectra for the P and M helicity of the [Zn-(R,R)-L]2 complex shows almost mirror-imaged ECD spectral features, whereas very similar ECD spectra were recently reported for the P- and M-dinuclear Mn complexes with a di-?-oxo dimetal core as a linker. We highlight the advantages of utilizing multiple chiroptical techniques and theoretical spectral simulations to correlate chiroptical spectral features with multiple chirality and helicity elements in the systems. PMID:25871769

  20. Hydrolysis of Letrozole catalyzed by macrocyclic Rhodium (I) Schiff-base complexes

    NASA Astrophysics Data System (ADS)

    Reddy, P. Muralidhar; Shanker, K.; Srinivas, V.; Krishna, E. Ravi; Rohini, R.; Srikanth, G.; Hu, Anren; Ravinder, V.

    2015-03-01

    Ten mononuclear Rhodium (I) complexes were synthesized by macrocyclic ligands having N4 and N2O2 donor sites. Square planar geometry is assigned based on the analytical and spectral properties for all complexes. Rh(I) complexes were investigated as catalysts in hydrolysis of Nitrile group containing pharmaceutical drug Letrozole. A comparative study showed that all the complexes are efficient in the catalysis. The percent yields of all the catalytic reaction products viz. drug impurities were determined by spectrophotometric procedures and characterized by spectral studies.

  1. DNA binding, cytotoxicity and apoptosis induction activity of a mixed-ligand copper(II) complex with taurine Schiff base and imidazole

    NASA Astrophysics Data System (ADS)

    Li, Mei; kong, Lin Lin; Gou, Yi; Yang, Feng; Liang, Hong

    2014-07-01

    A novel binuclear copper(II) complex (complex 1) with taurine Schiff base and imidazole has been synthesized and structurally characterized by single crystal X-ray diffraction, elemental analysis, ESI-MS spectrometry, UV-vis and IR spectroscopy. Single-crystal analysis revealed that 1 displays the sulfonate-bridged dinuclear copper(II) centers. Both copper atoms are five-coordinated and exhibit slightly distorted square pyramidal geometries. Each of copper atom is surrounded by three oxygen atoms and one nitrogen atom from different taurine Schiff base ligands, and one nitrogen atom from one imidazole ligand. The interaction between 1 and calf thymus DNA (CT-DNA) was investigated by UV-vis, fluorescence, circular dichroism (CD) spectra and agarose gel electrophoresis. The experimental results indicated that 1 could bind to CT-DNA via an intercalative mode and show efficient cleavage activity. In addition, 1 showed an antitumor effect on cell cycle and apoptosis. Flow cytometric analysis revealed that MGC-803 cells were arrested in the S phase after treatment with 1. Fluorescence microscopic observation indicated that 1 could induce apoptosis of MGC-803 cells.

  2. Synthesis, spectral characterization, DNA binding ability and antibacterial screening of copper(II) complexes of symmetrical NOON tetradentate Schiff bases bearing different bridges

    NASA Astrophysics Data System (ADS)

    Bahaffi, Saleh O.; Abdel Aziz, Ayman A.; El-Naggar, Maher M.

    2012-08-01

    A novel series of four copper(II) complexes were synthesized by thermal reaction of copper acetate salt with symmetrical tetradentate Schiff bases, N,N'bis(o-vanillin)4,5-dimethyl-l,2-phenylenediamine (H2L1), N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L2), N,N'bis(o-vanillin)4,5-dichloro-1,2-phenylenediamine (H2L3) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L4), respectively. All the new synthesized complexes were characterized by using of microanalysis, FT-IR, UV-Vis, magnetic measurements, ESR, and conductance measurements, respectively. The data revealed that all the Schiff bases (H2L1-4) coordinate in their deprotonated forms and behave as tetradentate NOON coordinated ligands. Moreover, their copper(II) complexes have square planar geometry with general formula [CuL1-4]. The binding of the complexes with calf thymus DNA (CT-DNA) was investigated by UV-Vis spectrophotometry, fluorescence quenching and viscosity measurements. The results indicated that the complexes bind to CT-DNA through an intercalative mode. From the biological activity view, the copper(II) complexes and their parent ligands were screened for their in vitro antibacterial activity against the bacterial species Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosai by well diffusion method. The complexes showed an increased activity in comparison to some standard drugs.

  3. Structural, spectral and biological studies of binuclear tetradentate metal complexes of N 3O Schiff base ligand synthesized from 4,6-diacetylresorcinol and diethylenetriamine

    NASA Astrophysics Data System (ADS)

    Emara, Adel A. A.

    2010-09-01

    The binuclear Schiff base, H 2L, ligand was synthesized by reaction of 4,6-diacetylresorcinol with diethylenetriamine in the molar ratio 1:2. The coordination behavior of the H 2L towards Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cr(III), VO(IV) and UO 2(VI) ions has been investigated. The elemental analyses, magnetic moments, thermal studies and IR, electronic, 1H NMR, ESR and mass spectra were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with two N 3O-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The bonding sites are the nitrogen atoms of the azomethine and amine groups and the oxygen atoms of the phenolic groups. The metal complexes exhibit either square planar, tetrahedral, square pyramid or octahedral structures. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria ( Staphylococcus aureus and Streptococcus pyogenes) as Gram-positive bacteria, and ( Pseudomonas fluorescens and Pseudomonas phaseolicola) as Gram-negative bacteria and two pathogenic fungi ( Fusarium oxysporum and Aspergillus fumigatus) to assess their antimicrobial properties. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

  4. DNA interaction, antimicrobial, electrochemical and spectroscopic studies of metal(II) complexes with tridentate heterocyclic Schiff base derived from 2‧-methylacetoacetanilide

    NASA Astrophysics Data System (ADS)

    Raman, Natarajan; Pothiraj, Krishnan; Baskaran, Thanasekaran

    2011-08-01

    A new Schiff base ligand (HL) was synthesized by the condensation reaction between 2'-methyleacetoacetanilide and 2-amino-3-hydroxypyridine. Its Co(II), Ni(II), Cu(II) and Zn(II) complexes were prepared by the interaction of the ligand with metal(II) chloride. They were characterized by elemental analysis, IR, 1H NMR, EPR, UV-Vis, magnetic susceptibility measurements, conductivity measurements and FAB-mass spectra. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by UV absorption, viscosity and cyclic voltammetry methods, and the mode of CT-DNA binding to the complexes has been explored. Furthermore, the DNA cleavage activity by the complexes was performed. It was found to be oxidative hydroxyl radical cleavage in the presence of 3-mercaptopropionic acid (MPA). The Schiff base and its complexes have been screened for their antibacterial ( Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal ( Aspergillus niger, Rhizopus stolonifer, Rhizoctonia bataicola and Candida albicans) activities and the data reveal that the complexes have higher activity than the free ligand.

  5. Synthesis, spectroscopy and biological investigations of manganese(III) Schiff base complexes derived from heterocyclic β-diketone with various primary amine and 2,2'-bipyridyl

    NASA Astrophysics Data System (ADS)

    Surati, Kiran R.

    2011-06-01

    The mixed ligand mononuclear complex [Mn(bipy)(HPMFP)(OAc)]ClO 4 was synthesized by reaction of Mn(OAc) 3·2H 2O with HPMFP and 2,2'-bipyridyl. The corresponding Schiff base complexes were prepared by condensation of [Mn(bipy)(HPMFP)(OAc)]ClO 4 with ethylenediamine, ethanolamine and glycine (where HPMFP = 1-phenyl-3methyl-4-formyl-2-pyrazolin-5one, bipy = 2,2'-bipyridyl). All the compounds have been characterized by elemental analysis, magnetic susceptibility, conductometry measurements and 1H and 13C NMR, FT-IR, mass spectrometry. Electronic spectral and magnetic susceptibility measurements indicate square pyramidal geometry around manganese(III) ion. The thermal stabilities, activation energy E*, entropy change Δ S*, enthalpy change Δ H* and heat capacity of thermal degradation for these complexes were determined by TGA and DSC. The in vitro antibacterial and antifungal activity of four coordination compounds and ligand HPMFP were investigated. In vitro activates of Bacillus subtillis (MTCC-619), Staphylococcus aureus (MTCC-96), Escherichia coli (MTCC-722) and Klebsiella pneumonia (MTCC-109) bacteria and the fungus Candida albicans (ATCC-90028) were determined. All the compounds showed good antimicrobial activity. The antimicrobial activities increased as formation of Schiff base.

  6. Ru(II) complexes of N 4 and N 2O 2 macrocyclic Schiff base ligands: Their antibacterial and antifungal studies

    NASA Astrophysics Data System (ADS)

    Shanker, Kanne; Rohini, Rondla; Ravinder, Vadde; Reddy, P. Muralidhar; Ho, Yen-Peng

    2009-07-01

    Reactions of [RuCl 2(DMSO) 4] with some of the biologically active macrocyclic Schiff base ligands containing N 4 and N 2O 2 donor group yielded a number of stable complexes, effecting complete displacement of DMSO groups from the complex. The interaction of tetradentate ligand with [RuCl 2(DMSO) 4] gave neutral complexes of the type [RuCl 2(L)] [where L = tetradentate macrocyclic ligand]. These complexes were characterized by elemental, IR, 1H, 13C NMR, mass, electronic, thermal, molar conductance and magnetic susceptibility measurements. An octahedral geometry has been proposed for all complexes. All the macrocycles and macrocyclic Ru(II) complexes along with existing antibacterial drugs were screened for antibacterial activity against Gram +ve ( Bacillus subtilis, Staphylococcus aureus) and Gram -ve ( Escherichia coli, Klebsiella pneumonia) bacteria. All these compounds were found to be more active when compared to streptomycin and ampicillin. The representative macrocyclic Schiff bases and their complexes were also tested in vitro to evaluate their activity against fungi, namely, Aspergillus flavus and Fusarium species.

  7. Solid state 15N NMR evidence for a complex Schiff base counterion in the visual G-protein-coupled receptor rhodopsin.

    PubMed

    Creemers, A F; Klaassen, C H; Bovee-Geurts, P H; Kelle, R; Kragl, U; Raap, J; de Grip, W J; Lugtenburg, J; de Groot, H J

    1999-06-01

    Using the baculovirus/Sf9 cell expression system, we have incorporated 99% 15N-enriched [alpha,epsilon-15N2]-L-lysine into the rod visual pigment rhodopsin. We have subsequently investigated the protonated Schiff base (pSB) linkage in the [alpha, epsilon-15N2]Lys-rhodopsin with cross-polarization magic angle spinning (CP/MAS) 15N NMR. The Schiff base (SB) 15N in [alpha, epsilon-15N2]Lys-rhodopsin resonates with an isotropic shift sigmaI of 155.9 ppm, relative to 5.6 M 15NH4Cl. This suggests that the SB in rhodopsin is protonated and stabilized by a complex counterion. The 15N shifts of retinal SBs correlate with the energy difference between the ground and excited states and the frequency of maximum visible absorbance, numax, associated with the pi-pi transition of the polyene chromophore. Experimental modeling of the relation between the numax and the size of the counterion with a set of pSBs provides strong evidence that the charged chromophore in rhodopsin is stabilized by a counterion with an estimated effective center-center distance (deff) between the counterion and the pSB of 0.43 +/- 0.01 nm. While selected prokaryotic proteins and complexes have been labeled before, this is the first time to our knowledge that a 15N-labeled eukaryotic membrane protein has been generated in sufficient amount for such NMR investigations. PMID:10353830

  8. Spectral characterization of novel ternary zinc(II) complexes containing 1,10-phenanthroline and Schiff bases derived from amino acids and salicylaldehyde-5-sulfonates

    NASA Astrophysics Data System (ADS)

    Boghaei, Davar M.; Gharagozlou, Mehrnaz

    2007-07-01

    A series of new ternary zinc(II) complexes [Zn(L 1-10)(phen)], where phen is 1,10-phenanthroline and H 2L 1-10 = tridentate Schiff base ligands derived from the condensation of amino acids (glycine, L-phenylalanine, L-valine, L-alanine, and L-leucine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5-sulfonate), have been synthesized. The complexes were characterized by elemental analysis, IR, UV-vis, 1H NMR, and 13C NMR spectra. The IR spectra of the complexes showed large differences between νas(COO) and νs(COO), Δ ν ( νas(COO) - νs(COO)) of 191-225 cm -1, indicating a monodentate coordination of the carboxylate group. Spectral data showed that in these ternary complexes the zinc atom is coordinated with the Schiff base ligand acts as a tridentate ONO moiety, coordinating to the metal through its phenolic oxygen, imine nitrogen, and carboxyl oxygen, and also with the neutral planar chelating ligand, 1,10-phenanthroline, coordinating through nitrogens.

  9. Synthesis, spectral characterization, molecular modeling, biological activity and potentiometric studies of 4-amino-5-mercapto-3-methyl-S-triazole Schiff's base complexes

    NASA Astrophysics Data System (ADS)

    Alaghaz, Abdel-Nasser M. A.; Zayed, Mohamed E.; Alharbi, Suliman A.

    2015-03-01

    The Schiff's base derived from condensation of s-triazole (4-amino-5-mercapto-3-methyl-S-triazole) with pyridine-2-aldehyde and their corresponding Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes have been synthesized. The isolated solid complexes were characterized by elemental analyses, molar conductance, spectral (IR, UV-Vis, 1H NMR, mass), magnetic moment and thermal measurements. The IR spectral data suggest that the ligand coordinate in a tridentate manner (SNN) via the one thiol (SH), one pyridine ring and the azomethine (Cdbnd N) groups. The data show that the complexes have composition of ML2 type. The activation of thermodynamic parameters are calculated using Coats-Redfern, Horowitz-Metzger (HM), and Piloyan-Novikova (PN). The octahedral geometry of the complexes is confirmed using DFT method from DMOL3 calculations and ligand field parameters. Protonation constants of Schiff base and stability constants of their binary metal complexes have been determined potentiometrically in 50% DMSO-water media at 25 C and ionic strength 0.10 M potassium nitrate. The biological activity of these compounds against various fungi has been investigated.

  10. Synthesis, Characterization, Antimicrobial, DNA Cleavage, and Antioxidant Studies of Some Metal Complexes Derived from Schiff Base Containing Indole and Quinoline Moieties

    PubMed Central

    Karekal, Mahendra Raj; Biradar, Vivekanand; Bennikallu Hire Mathada, Mruthyunjayaswamy

    2013-01-01

    A new Schiff base of 5-chloro-3-phenyl-1H-indole-2-carboxyhydrazide and 3-formyl-2-hydroxy-1H-quinoline (HL), and its Cu(II), Co(II), Ni(II), Zn(II), Cd(II), and Hg(II) complexes have been synthesized and characterized in the light of microanalytical, IR, H1 NMR, UV-Vis, FAB-mass, ESR, XRD, and TGA spectral studies. The magnetic susceptibility measurements and low conductivity data provide evidence for monomeric and neutral nature of the complexes. On the basis of spectral studies and analytical data, it is evident that the Schiff base acts as tridentate ligand. The Cu(II), Co(II), and Ni(II) complexes were octahedral, whereas Zn(II), Cd(II), and Hg(II) complexes were tetrahedral in nature. The redox behavior of the Cu(II) complex was investigated by electrochemical method using cyclic voltammetry. In order to evaluate the effect of metal ions upon chelation, both the ligand and its metal complexes were screened for their antibacterial and antifungal activities by minimum inhibitory concentration (MIC) method. The DNA cleavage experiment performed using agarose gel electrophoresis method showed the cleavage of DNA by all the metal complexes. The free radical scavenging activity of newly synthesized compounds has been determined at a different concentration range by means of their interaction with the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH). PMID:24194692

  11. [Mn(III)(Schiff base)]?[Re(IV)(CN)?], highly anisotropic 3D coordination framework: synthesis, crystal structure, magnetic investigations, and theoretical analysis.

    PubMed

    Samsonenko, Denis G; Paulsen, Carley; Lhotel, Elsa; Mironov, Vladimir S; Vostrikova, Kira E

    2014-10-01

    A new highly anisotropic coordination heterobimetallic polymer [Mn(III)(Schiff-base)]3[Re(IV)(CN)7] was synthesized and characterized structurally and magnetically. The single crystal X-ray analysis has revealed that this is the first framework among the complexes composed of homoleptic cyanometallate and Mn(III) complex of the tetradentate Schiff base ligand. A formation of 3D assembly is possible due to both the pentagonal bipyrimidal geometry of the cyanometallate unit and suitable size of constituents: [Re(CN)7](3-) and [Mn(III)(acacen)](+), where acacen = N,N'-ethylenebis(acetylacetoneiminato). The powder and crystal magnetic studies show that the compound undergoes an antiferromagnetic ordering of a complicated character below Neel temperature of 13 K, and exhibits a metamagnetic behavior and strong magnetic anisotropy similar to those observed in related 3D Mn(II)-[Mo(CN)7](4-) systems. Unusual magnetic properties of [Mn(III)(acacen)]3[Re(IV)(CN)7] (1) originate from an interplay of Re-Mn anisotropic spin coupling and ZFS effect of Mn(III) ions with a noncollinear orientation of the local magnetic axes in the cyano-bridged 3D network. A theoretical model of anisotropic spin coupling between orbitally degenerate [Re(IV)(CN)7](3-) complexes and Mn(III) ions is developed, and specific microscopic mechanisms of highly anisotropic spin coupling in Re(IV)-CN-Mn(III) linkages in complex 1 are analyzed in detail. PMID:25250555

  12. DNA cleavage, antimicrobial, spectroscopic and fluorescence studies of Co(II), Ni(II) and Cu(II) complexes with SNO donor coumarin Schiff bases

    NASA Astrophysics Data System (ADS)

    Patil, Sangamesh A.; Naik, Vinod H.; Kulkarni, Ajaykumar D.; Badami, Prema S.

    2010-01-01

    A series of Co(II), Ni(II) and Cu(II) complexes of the type ML 2 have been synthesized with Schiff bases derived from methylthiosemicarbazone and 5-formyl-6-hydroxy coumarin/8-formyl-7-Hydroxy-4-methylcoumarin. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMF indicate that, the complexes are non-electrolytes in nature. In view of analytical, spectral (IR, UV-vis, ESR, FAB-mass and fluorescence), magnetic and thermal studies, it has been concluded that, all the metal complexes possess octahedral geometry in which ligand is coordinated to metal ion through azomethine nitrogen, thione sulphur and phenolic oxygen atom via deprotonation. The redox behavior of the metal complexes was investigated by using cyclic voltammetry. The Schiff bases and their complexes have been screened for their antibacterial ( Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi) and antifungal activities ( Aspergillus niger, Aspergillus flavus and Cladosporium) by Minimum Inhibitory Concentration method. The DNA cleavage is studied by agarose gel electrophoresis method.

  13. Substitutional group dependent colori/fluorimetric sensing of Mn2+, Fe3+ and Zn2+ ions by simple Schiff base chemosensor

    NASA Astrophysics Data System (ADS)

    Hariharan, P. S.; Anthony, Savarimuthu Philip

    2015-02-01

    Schiff base is one of the easiest synthesizable chemosensor and exhibit strong coordination with metal ions; the property that has been vastly exploited for metal ions sensing. Simple Schiff base chemosensors (1a-d and 2a-d) were synthesized and demonstrated substitutional group dependent colorimetric sensing of metal ions. Chemosensor without (1a, 2a) and OCH3 substitution (1b, 2b) did not show any significant colour change for metal ions. However, a highly selective colorimetric change (colourless to pink) for Mn2+ ions (10-6 M) was observed with diethylamine substituted 1c, 2c. Hydroxyl substitution (1d, 2d) leads to selective colorimetric sensing (colourless to orange) of Fe3+ ions (10-6 M). PVA thin films of 2c/2d were fabricated and demonstrated selective colorimetric sensing of Mn2+ and Fe3+ ions. The practical applicability of the synthesized chemosensors were also demonstrated by performing selective colorimetric sensing of Mn2+ and Fe3+ ions in real samples such as tap, ground, pond and river water. Effect of substitution on the fluorescence selectivity of Zn2+ has also been investigated.

  14. Synthesis, characterization, single crystal X-ray determination, fluorescence and electrochemical studies of new dinuclear nickel(II) and oxovanadium(IV) complexes containing double Schiff base ligands

    NASA Astrophysics Data System (ADS)

    Shafaatian, Bita; Ozbakzaei, Zahra; Notash, Behrouz; Rezvani, S. Ahmad

    2015-04-01

    A series of new bimetallic complexes of nickel(II) and vanadium(IV) have been synthesized by the reaction of the new double bidentate Schiff base ligands with nickel acetate and vanadyl acetylacetonate in 1:1 M ratio. In nickel and also vanadyl complexes the ligands were coordinated to the metals via the imine N and enolic O atoms. The complexes have been found to possess 1:1 metals to ligands stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The nickel and vanadyl complexes exhibited distorted square planar and square pyramidal coordination geometries, respectively. The emission spectra of the ligands and their complexes were studied in methanol. Electrochemical properties of the ligands and their metal complexes were also investigated in DMSO solvent at 150 mV s-1 scan rate. The ligands and metal complexes showed both quasi-reversible and irreversible processes at this scan rate. The Schiff bases and their complexes have been characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis and conductometry. The crystal structure of the nickel complex has been determined by single crystal X-ray diffraction.

  15. A new series of Schiff bases derived from sulfa drugs and indole-3-carboxaldehyde: Synthesis, characterization, spectral and DFT computational studies

    NASA Astrophysics Data System (ADS)

    Ebrahimi, H.; Hadi, J. S.; Al-Ansari, H. S.

    2013-05-01

    A new series of Schiff bases were synthesized for the first time by the condensation of indole-3-carboxaldehyde with various sulfa drugs including sulfanilamide, sulfapyridine, sulfadiazine, sulfamerazine, sulfamethoxazole, sulfamethoxypyridazine and sulfacetamide sodium in ethanol (1:1). The structure of Schiff bases were experimentally characterized by using IR, 1H NMR, 13C NMR and mass spectroscopic methods. The structural and electronic properties of the studied molecules were investigated theoretically by performing density functional theory (DFT) to access reliable results to the experimental values. The molecular geometry, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and Mulliken atomic charges of the studied molecules have been calculated at the B3LYP method and standard 6-31 + G(d,p) basis set starting from optimized geometry. The theoretical 13C chemical shift results were also calculated using the gauge independent atomic orbital (GIAO) approach and their respective linear correlations were obtained. The comparison of the results indicates that B3LYP/6-31 + G(d,p) yields good agreement with the observed chemical shifts.

  16. Accommodation of Mn II, Mn III-N, O, O, O-donor Schiff base complexes in zeolite-Y: Synthesis, structural studies and CO adsorption

    NASA Astrophysics Data System (ADS)

    Ahmed, Ayman H.; El-Bahy, Zeinhom M.; Salama, Tarek M.

    2010-04-01

    Manganese (II)-, (III)-complexes with NO 3 Schiff base ligand (SPAB) derived from salicylaldehyde and p-aminobenzoic acid have been synthesized and immobilized in the zeolite-Y supercages by a flexible ligand method. The synthesized new host/guest materials have been characterized by various physicochemical techniques, in addition to surface area measurements and nitrogen adsorption studies. Investigation of the stereochemistry of these incorporated chelates elucidated that, Mn(II) complex is tetrahedral with involvement of zeolite oxygen in coordination meanwhile Mn(III) complex has octahedral configuration with Jahn-Teller distortion but without contribution of the lattice oxygen. The intrazeolitic Schiff base complexes are thermally stable up to ?600 C without any decomposition. Catalytic activity towards CO adsorption for zeolite-encapsulated complexes has been investigated and compared with Mn II-Y using in situ FT-IR spectroscopy. The results pointed out that, encapsulation of manganese (II, III) complexes in zeolites enhances remarkably the selectivity towards the formation of unionized carboxyl (-COOH) species which is considered a characteristic property of the zeolite encapsulated Mn(II,III)-SPAB complexes over Mn II-Y. On the other hand, the in situ FT-IR data demonstrate that Mn II(SPAB)/Y and Mn III(SPAB)/Y can be used as reactive catalysts in water gas shift reaction (WGSR).

  17. Synthesis, characterization and electrochemical behaviour of cobalt(II) and cobalt(III):O 2- complexes, respectively, with linear and tripodal tetradentate ligands derived from Schiff bases

    NASA Astrophysics Data System (ADS)

    Djebbar-Sid, S.; Benali-Baitich, O.; Deloume, J. P.

    2001-07-01

    New octahedral cobalt complexes with linear and tripodal tetradentate ligands derived from Schiff bases have been synthesized and characterized using elemental analysis, molar conductance, IR spectra, magnetic measurements, electronic and ESR spectra. The experimental results support the binding of linear ligands with two N and two O donor sites to cobalt ion. They show a square planar geometry and tripodal ligands coordinated to the metal ion by only one nitrogen atom, giving an arrangement of NO 3 donor groups, the other axial sites being occupied by the molecular oxygen and/or the aquo molecules. From the results of cyclic voltammetry it is shown that chelate structure and ligand geometry and electron donating effect of the ligand substituents are among the factors influencing the redox potentials of the complexes. Linear ligands lead to high-spin cobalt(II) complexes. They do not interact with dioxygen and stabilize the Co(II) state counter to their related Schiff-base complexes. The low-spin complexes with tripodal ligands are O 2 adducts and the configuration in these complexes is best formulated as [Co IIIO 2-].

  18. Spin Crossover Properties of Iron(ii) Complexes with a N4O2 Donor Set by Extended ?-CONJUGATED Schiff-Base Ligands

    NASA Astrophysics Data System (ADS)

    Kuroda, Takayoshi

    2013-09-01

    The preparation and magnetic properties of three Fe(II) Schiff-base complexes, [Fe(qnal-21)2]CH2Cl2 (1), [Fe(qnal-12)2]2C6H6 (2) and [Fe(Hqsalc)2] (3), (Hqnal-21 = N-(8'-quinolyl)-2-hydroxy-1-naphthaldimine, Hqnal-12 = N-(8'-quinolyl)-1-hydroxy-2-naphthaldimine, H2qsalc = 4-hydroxy-3-[(8-quinolinylimino)methyl]benzoic acid) are reported. X-ray single crystal structure analyses of 1 and 2 reveal that an Fe(II) ion in each complex is coordinated by two Schiff-base ligands, qnal-21 or qnal-12, in a meridional fashion. Molecular packing of 2 shows that a qnal-12 interacts with neighboring two qnal-12's through ?-? interactions, which results in the formation of one-dimensional chain. Although the magnetic property of 2 shows a high-spin state at all the temperature range measured, the ?T-T plot of 3 shows abrupt spin crossover behavior with a wide hysteresis of 21 K, probably due to the hydrogen-bond network originated by carboxyl groups.

  19. Synthesis, experimental and theoretical characterization of N,N'-dipyridoxyl (1,4-butanediamine) Schiff-base ligand and its Cu(II) complex

    NASA Astrophysics Data System (ADS)

    Eshtiagh-Hosseini, Hossein; Housaindokht, Mohammad R.; Beyramabadi, S. Ali; Tabatabaei, S. Hamid Mir; Esmaeili, Abbas Ali; Javan Khoshkholgh, Malihe

    2011-03-01

    A new N,N'-dipyridoxyl(1,4-butanediamine) [=H 2BS] Schiff-base ligand and its Cu(II) salen complex, [Cu(BS)(H 2O)(CH 3OH)], were synthesized and characterized by IR, UV-vis, 1H NMR, mass spectrometry and elemental analysis. Also, full optimization of the geometries, 1H NMR chemical shifts (for the H 2BS) and vibrational frequencies were calculated by using density functional theory (DFT) method. Structure of the H 2BS ligand is not planar, i.e. two pyridine rings are not in the same plane. In the structure of the Cu complex, the Schiff-base ligand acts as a dianionic tetradentate ligand in N, N, O -, O - manner. The coordinating atoms of BS 2- occupy equatorial positions of the octahedral complex, where the H 2O and CH 3OH ligands locate at axial positions. The calculated results are in good agreement with the experimental data, confirming the suitability of the proposed and optimized structures for the H 2BS ligand and its Cu complex.

  20. Spectral characterization, optical band gap calculations and DNA binding of some binuclear Schiff-base metal complexes derived from 2-amino-ethanoic acid and acetylacetone

    NASA Astrophysics Data System (ADS)

    Hussien, Mostafa A.; Nawar, Nagwa; Radwan, Fatima M.; Hosny, Nasser Mohammed

    2015-01-01

    Bi-nuclear metal complexes derived from the reaction of Cu(II), Co(II), Ni(II) and Zn(II) acetates with the Schiff-base ligand (H2L) resulted from the condensation of 2-amino-ethanoic acid (glycine) and acetylacetone have been synthesized and characterized by elemental analyses, Raman spectra, FT-IR, ES-MS, UV-Vis., 1H NMR, ESR, thermal analyses (TG, DTG and DTA) and magnetic measurements. The results showed that, the Schiff base ligand can bind two metal ions in the same time. It coordinates to the first metal ion as mono-negative bi-dentate through azomethine nitrogen and enolic carbonyl after deprotonation. At the same time, it binds to the second metal ion via carboxylate oxygen after deprotonation. The thermodynamic parameters E?, ?H?, ?G? and ?S? have been calculated by Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. The optical band gaps of the isolated complexes have been calculated from absorption spectra and the results indicated semi-conducting nature of the investigated complexes. The interactions between the copper (II) complex and calf thymus DNA (CT-DNA) have been studied by UV spectra. The results confirm that the Cu(II) complex binds to CT-DNA.

  1. Solvent extraction of palladium(II) with a Schiff base and separation of palladium from Pd(II)-Pt(VI) mixture

    SciTech Connect

    Ouyang, J.M.

    1999-09-01

    A new Schiff base extractant, N,N{prime}-bis[1-phenyl-3-methyl-5-hydroxy-pyrazole-4-benzylidenyl]-1,3-propylene diamine (H{sub 2}A) was synthesized and characterized. The extraction mechanism of palladium(II) from HNO{sub 3} or HCIO{sub 2} medium with H{sub 2}A in chloroform or toluene was investigated. The influences of the Schiff base concentration in the organic phase, the concentration of palladium, the pH and anions (Cl{sup {minus}}, SO{sub 4}{sup =}, NO{sub 3}{sup {minus}}, ClO{sub 4}{sup {minus}}) in the aqueous phase and the temperature on the distribution ration for palladium (II) have been examined. The extracted complex has been confirmed by chemical analysis, thermoanalyses and IR spectroscopy. It was found that palladium is extracted according to the following extraction reaction: Pd(H{sub 2}O){sub 2}Cl{sub 2(a)} + H{sub 2}A{sub (o)} == Pd(HA)Cl{sub (o)}+H{sup +}{sub (a)} + Cl{sup {minus}}{sub (a)} + 2H{sub 2}O. The extraction equilibrium constants of palladium(II) were 8.4 and 21.3 in chloroform and toluene diluents, respectively. The values for the enthalpy and standard free energy of extraction were also obtained. The separation of Pd(II) from the mixed solution of Pd(II)-Pt(IV) was achieved by adjusting the pH.

  2. Covalent functionalization of multi-wall carbon nanotubes (MWNTs) by nickel(II) Schiff-base complex: Synthesis, characterization and liquid phase oxidation of phenol with hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Salavati-Niasari, Masoud; Bazarganipour, Mehdi

    2008-12-01

    The chemical modification of multi-wall carbon nanotubes (MWNTs) is an emerging area in material science. In the present study, hydroxyl functionalized nickel(II) Schiff-base has been covalently anchored on modified MWNTs. The new modified MWNTs have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), thermal analysis, UV-vis, diffuse reflectance (DRS), FT-IR spectroscopy and elemental analysis. The results suggest that the symmetrical Schiff-base; N, N'-bis(4-hydroxysalicylidene)-ethylene-1,2-diamine; H 2[(OH) 2-salen]; is a bivalent anion with tetradentate N 2O 2 donors derived from the phenolic oxygen and azomethine nitrogen. The formula was found to be [Ni((OH) 2-salen)] for the 1:1 non-electrolytic complex. Multi-wall carbon nanotubes covalently anchored nickel(II) complex ([Ni((OH) 2-salen)]@MWNTs) catalyze the oxidation of phenol with H 2O 2. Oxidation of phenol catalyzed by this complex gave catechol and hydroquinone as major products. A suitable reaction condition has been optimized for [Ni((OH) 2-salen)]@MWNTs by considering the effect of various parameters such as reaction time and amount of oxidant, different solvents, concentration of substrate, etc. for the maximum transformation of phenol.

  3. Construction and NIR luminescent property of hetero-bimetallic Zn Nd complexes from two chiral salen-type Schiff-base ligands

    NASA Astrophysics Data System (ADS)

    Bi, Wei-Yu; L, Xing-Qiang; Chai, Wen-Li; Song, Ji-Rong; Wong, Wai-Yeung; Wong, Wai-Kwok; Jones, Richard A.

    2008-11-01

    Two new near-infrared (NIR) luminescent Zn-Nd complexes [ZnL 1Nd(OAc)(NO 3) 2] ( 3) and [ZnL 2Nd(DMF) 2(NO 3) 3] ( 4) have been obtained with two salen-type Schiff-base ligands H 2L 1 and H 2L 2, ( H 2L 1 = N, N'-bis(3-methoxysalicylidene)-(1s, 2s)-(-)1,2-dipheneylethylenediamine and H 2L 2 = N, N'-bis(3-methoxysalicylidene)-(s)-2,2-diamine-1,1'-binaphthyl) from the reaction of different chiral diamines with o-vanillin. The X-ray crystal structure analysis reveals that both of them crystallize in the chiral space groups with P2(1), a = 10.1669(6), b = 19.3775(11), c = 17.4639(10) , ? = 94.8710(10), V = 3428.1(3) 3, Z = 4 for 3, and C2, a = 22.1914(13), b = 9.7886(6), c = 22.0138(13) , ? = 118.9590(10), V = 4372.5(4) 3, Z = 4 for 4. Complexes 3- 4 are both dinuclear Zn-Nd structures, while suitable choice of chiral Schiff-base ligands could induce the different complexions of ligands and metal ions, and the functional control of ligand character shows a potentially effective way to the fine-tuning properties of NIR luminescence from Nd ions.

  4. Spectroscopic and biological activities studies of bivalent transition metal complexes of Schiff bases derived from condensation of 1,4-phenylenediamine and benzopyrone derivatives

    NASA Astrophysics Data System (ADS)

    Sherif, Omaima E.; Abdel-Kader, Nora S.

    2014-01-01

    Many tools of analysis such as elemental analyses, infrared, ultraviolet-visible, electron spin resonance (ESR) and thermal analysis, as well as conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared Co(II), Ni(II) and Cu(II) complexes with Schiff bases derived from the condensation of 1,4-phenylenediamine with 6-formyl-7-hydroxy-5-methoxy-2-methylbenzo-pyran-4-one (H2L) or 5,7-dihydroxy-6-formyl-2-methylbenzopyran-4-one (H4L). The data showed that all formed complexes are 1:1 or 2:2 (M:L) and non-electrolyte chelates. The Co(II) and Cu(II) complexes of the two Schiff bases were screened for antibacterial activities by the disk diffusion method. The antibacterial activity was screened using Escherichia coli and Staphylococcus capitis but the antifungal activity was examined by using Aspergillus flavus and Candida albicans. The Results showed that the tested complexes have antibacterial, except Cusbnd H4L, but not antifungal activities.

  5. Identical Hydrogen-Bonding Strength of the Retinal Schiff Base between Primate Green- and Red-Sensitive Pigments: New Insight into Color Tuning Mechanism.

    PubMed

    Katayama, Kota; Okitsu, Takashi; Imai, Hiroo; Wada, Akimori; Kandori, Hideki

    2015-04-01

    Three aspects are generally considered in the color-tuning mechanism of vision: (I) chromophore distortion, (II) electrostatic interaction between the protonated Schiff base and counterion, and (III) polarity around the β-ionone ring and polyene chain. Primate green- and red-sensitive proteins are highly homologous but display maximum absorption at 530 and 560 nm, respectively. In the present study, the N-D stretching frequency of monkey green-sensitive protein was identified by using C15-D retinal. The hydrogen-bonding strength between monkey green and red was identical. Together with a previous resonance Raman study, we conclude that the 30 nm difference originates exclusively from the polarity around the β-ionone ring and polyene chain. Three amino acids (Ala, Phe, and Ala in monkey green and Ser, Tyr, and Thr in monkey red, respectively) may be responsible for color tuning together with protein-bound water molecules around the β-ionone ring and polyene chain but not at the Schiff base region. PMID:26262961

  6. Synthesis, crystal structure and interaction of L-valine Schiff base divanadium(V) complex containing a V2O3 core with DNA and BSA

    NASA Astrophysics Data System (ADS)

    Guo, Qiong; Li, Lianzhi; Dong, Jianfang; Liu, Hongyan; Xu, Tao; Li, Jinghong

    2013-04-01

    A divanadium(V) complex, [V2O3(o-van-val)2] (o-van-val = Schiff base derived from o-vanillin and L-valine), has been synthesized and structurally characterized. The crystal structure shows that both of the vanadium centers in the complex have a distorted octahedral coordination environment composed of tridentate Schiff base ligand. A V2O3 core in molecular structure adopts intermediate between cis and trans configuration with the O1dbnd V1⋯V1Adbnd O1A torsion angle 115.22 (28) and the V1⋯V1A distance 3.455 . The binding properties of the complex with calf thymus DNA (CT-DNA) have been investigated by UV-vis absorption, fluorescence, CD spectra and viscosity measurement. The results indicate that the complex binds to CT-DNA in non-classical intercalative mode. Meanwhile, the interaction of the complex with bovine serum albumin (BSA) has been studied by UV-vis absorption, fluorescence and CD spectra. Results indicated that the complex can markedly quench the intrinsic fluorescence of BSA via a static quenching process, and cause its conformational change. The calculated apparent binding constant Kb was 1.05 106 M-1 and the binding site number n was 1.18.

  7. Synthesis, characterization, single crystal X-ray determination, fluorescence and electrochemical studies of new dinuclear nickel(II) and oxovanadium(IV) complexes containing double Schiff base ligands.

    PubMed

    Shafaatian, Bita; Ozbakzaei, Zahra; Notash, Behrouz; Rezvani, S Ahmad

    2015-04-01

    A series of new bimetallic complexes of nickel(II) and vanadium(IV) have been synthesized by the reaction of the new double bidentate Schiff base ligands with nickel acetate and vanadyl acetylacetonate in 1:1 M ratio. In nickel and also vanadyl complexes the ligands were coordinated to the metals via the imine N and enolic O atoms. The complexes have been found to possess 1:1 metals to ligands stoichiometry and the molar conductance data revealed that the metal complexes were non-electrolytes. The nickel and vanadyl complexes exhibited distorted square planar and square pyramidal coordination geometries, respectively. The emission spectra of the ligands and their complexes were studied in methanol. Electrochemical properties of the ligands and their metal complexes were also investigated in DMSO solvent at 150 mV s(-1) scan rate. The ligands and metal complexes showed both quasi-reversible and irreversible processes at this scan rate. The Schiff bases and their complexes have been characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis and conductometry. The crystal structure of the nickel complex has been determined by single crystal X-ray diffraction. PMID:25613693

  8. A family of dinuclear lanthanide(III) complexes from the use of a tridentate Schiff base.

    PubMed

    Anastasiadis, Nikolaos C; Kalofolias, Dimitris A; Philippidis, Aggelos; Tzani, Sofia; Raptopoulou, Catherine P; Psycharis, Vassilis; Milios, Constantinos J; Escuer, Albert; Perlepes, Spyros P

    2015-06-14

    The use of N-salicylidene-o-aminophenol (H2saph) in 4f-metal chemistry has led to the isolation of seven new isostructural lanthanide(iii) [Ln(III)] complexes. More specifically the Ln(NO3)3xH2O/H2saph/Et3N (1?:?1?:?1) reaction mixtures in DMF/MeCN gave complexes [Ln2(NO3)2(saph)2(DMF)4] (Ln = Sm (); Eu (); Gd (); Tb (); Dy (); Ho (); Er ()) in good yields (?65%). The structures of the isomorphous complexes and were solved by single-crystal X-ray crystallography; the other complexes are proposed to be isostructural with and based on elemental analyses, IR spectra and powder XRD patterns. The two Ln(III) atoms in the centrosymmetric molecules of and are doubly bridged by the deprotonated iminophenolato oxygen atoms of two nearly planar ?(1):?(1):?(2):? saph(2-) ligands. The imino nitrogen and five terminal oxygen atoms (the salicylaldiminate, two from one bidentate chelating nitrato group and two from two DMF ligands) complete square antiprismatic coordination at each metal centre. The IR spectra of the complexes are discussed in terms of the coordination modes of the ligands present in the complexes. Solid-state emission studies for all display identical ligand-based photoluminescence. Dc magnetic susceptibility studies in the 2-300 K range reveal the presence of a weak, intramolecular antiferromagnetic exchange interaction (J = -0.19(1) cm(-1) based on the spin Hamiltonian H = -J(?Gd?Gd')) for and probably ferromagnetic exchange interaction within the molecules of and . Ac magnetic susceptibility measurements in zero dc field show temperature- and frequency-dependent out-of-phase signals with two well defined, thermally-activated processes for , suggesting potential single-molecule magnetism character. The Ueff value is 17.4 cm(-1) for the higher temperature process and 16.2 cm(-1) for the lower temperature one. The combination of photoluminescence and single-molecule behaviour in the Dy complex is critically discussed. PMID:25952755

  9. Synthesis of Schiff Base Bearing Phenolic Hydroxy Group and Its Anion Recognition

    NASA Astrophysics Data System (ADS)

    Liu, Ge; Gao, Ling

    2011-06-01

    A new anion receptor bearing phenolic hydroxy group based on 3,5-ditertbutylsalicylaldehyde-p-nitrophenylhydrazone (1) was designed and synthesized. Upon addition of AcO- and F-, the receptor exhibited visible color changes from deep yellow to purple. However, no obvious color changes were observed on addition of the other anions tested (H2PO4-, Cl-, Br-, I-). The binding properties of the receptor with anions such as AcO- and F- were investigated by UV-Vis and fluorescent titrations. The result indicated that the receptor 1 had a higher affinity to AcO- and F- and a 1:1 host-guest complex was formed through H-bond interactions between 1 and anions.

  10. Synthesis, characterization and antimicrobial activities of mixed ligand transition metal complexes with isatin monohydrazone Schiff base ligands and heterocyclic nitrogen base

    NASA Astrophysics Data System (ADS)

    Devi, Jai; Batra, Nisha

    2015-01-01

    Mixed ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with various uninegative tridentate ligands derived from isatin monohydrazone with 2-hydroxynapthaldehyde/substituted salicylaldehyde and heterocyclic nitrogen base 8-hydroxyquinoline have been synthesized and characterized by elemental analysis, conductometric studies, magnetic susceptibility and spectroscopic techniques (IR, UV-VIS, NMR, mass and ESR). On the basis of these characterizations, it was revealed that Schiff base ligands existed as monobasic tridentate ONO bonded to metal ion through oxygen of carbonyl group, azomethine nitrogen and deprotonated hydroxyl oxygen and heterocyclic nitrogen base 8-hydroxyquinoline existed as monobasic bidentate ON bonded through oxygen of hydroxyl group and nitrogen of quinoline ring with octahedral or distorted octahedral geometry around metal ion. All the compounds have been tested in vitro against various pathogenic Gram positive bacteria, Gram negative bacteria and fungi using different concentrations (25, 50, 100, 200 ?g/mL) of ligands and their complexes. Comparative study of antimicrobial activity of ligands, and their mixed complexes indicated that complexes exhibit enhanced activity as compared to free ligands and copper(II) Cu(LIV)(Q)?H2O complex was found to be most potent antimicrobial agent.

  11. Dynamical Correlation Effects on Photoisomerization: Ab Initio Multiple Spawning Dynamics with MS-CASPT2 for a Model trans-Protonated Schiff Base.

    PubMed

    Liu, Lihong; Liu, Jian; Martinez, Todd J

    2016-03-01

    We investigate the photoisomerization of a model retinal protonated Schiff base (trans-PSB3) using ab initio multiple spawning (AIMS) based on multistate second order perturbation theory (MSPT2). Discrepancies between the photodynamical mechanism computed with three-root state-averaged complete active space self-consistent field (SA-3-CASSCF, which does not include dynamic electron correlation effects) and MSPT2 show that dynamic correlation is critical in this photoisomerization reaction. Furthermore, we show that the photodynamics of trans-PSB3 is not well-described by predictions based on minimum energy conical intersections (MECIs) or minimum energy conical intersection (CI) seam paths. Instead, most of the CIs involved in the photoisomerization are far from MECIs and minimum energy CI seam paths. Thus, both dynamical nuclear effects and dynamic electron correlation are critical to understanding the photochemical mechanism. PMID:26679298

  12. A Novel Fluorescent Optode for Recognition of Zn(2+) ion Based on N,N(')-bis-(1-Hydroxypheylimine)2,5-Thiophenedicarobxaldehyde (HPTD) Schiff Base.

    PubMed

    Abdel Aziz, Ayman A; Seda, Sabry H

    2015-11-01

    A novel fluorescent sensing film has been proposed for sensitive determination of Zn(2+) ion in EtOH-HEPES buffer solution (20 mM HEPES, 50:50, v/v, pH 7.0). The novel sensor based on incorporating a novel qaudridentate Schiff base N,N(')-bis-(1-hydroxypheylimine)2,5-thiophenedicarobxaldehyde (HPTD) as ionophore in the plasticized PVC membrane containing bis(2-ethylhexyl)sebecate (DOS) as plasticizer. The novel optode membrane works on the basis of a cation-exchange mechanism and shows a significant fluorescent emission enhancement on exposure to HEPES buffer solution of pH7.0 containing Zn(2+) ion. Under optimal conditions, the proposed sensing film displays a linear range of 1.0נ10(-12) to 8.6נ10(-4) M with a limit of detection 5.3נ10(-13) M. The response characteristics of the sensor including reversibility, reproducibility, response time and lifetime are discussed in detail. The optode membrane has been applied to determine Zn(2+) in various real water samples. PMID:26438657

  13. Synthesis and spectral characterization of Schiff base complexes of Cu(II), Co(II), Zn(II) and VO(IV) containing 4-(4-aminophenyl)morpholine derivatives: antimicrobial evaluation and anticancer studies.

    PubMed

    Dhahagani, K; Mathan Kumar, S; Chakkaravarthi, G; Anitha, K; Rajesh, J; Ramu, A; Rajagopal, G

    2014-01-01

    Metal(II) chelates of Schiff bases derived from the condensation of 4-morpholinoaniline with substituted salicylaldehyde have been prepared and characterized by (1)H NMR, IR, electronic, EPR, and magnetic measurement studies. The complexes are of the type M(X-MPMP)2 [where M=Cu(II), Co(II)), Zn(II), or VO(IV); MPMP=2-[(4 morpholinophenyl imino) methyl] 4-X-phenol, X=Cl, (L1H), X=Br (L2H)]. Single crystal X-ray crystallography studies confirm the structure of newly synthesized Schiff bases. The Schiff bases act as bidentate monobasic ligands, coordinating through deprotonated phenolic oxygen and azomethine nitrogen atoms. The free ligands and metal complexes are screened for their biopotency. Metal complexes exhibit better activity than ligands. Anticancer activity of ligands and their metal complexes are evaluated in human heptocarcinoma(HepG2) cells. The preliminary bioassay indicates that the Schiff base and its zinc complex exhibit inhibitory activity against the human gastric cancer cell lines. PMID:23985482

  14. Synthesis, spectral and antimicrobial activity of Zn(II) complexes with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and benzaldehyde/2-hydroxyacetophenone/indoline-2,3-dione

    NASA Astrophysics Data System (ADS)

    Singh, Ajay K.; Pandey, O. P.; Sengupta, S. K.

    2013-09-01

    Zn(II) complexes have been synthesized by reacting zinc acetate with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and 2-hydroxyacetophenone/benzaldehyde/indoline-2,3-dione. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non electrolytes. Elemental analyses suggest that the complexes have 1:2 metal to ligands stoichiometry of the types [ZnL2(H2O)2](L = monoanionic Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and 2-hydroxyacetophenone/indoline-2,3-dione) [ZnL2‧(OOCCH3)2(H2O)2](L‧ = neutral Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and benzaldehyde), and they were characterized by IR, 1H NMR, and 13C NMR. Particle sizes of synthesized compounds were measured with dynamic light scattering (DLS) analyser which indicates that particle diameter are of the range ca. 100-200 nm. All these Schiff bases and their complexes have also been screened for their antibacterial (Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and antifungal activities (Colletotrichum falcatum (C. falcatum), Aspergillus niger (A. niger), Fusarium oxysporium (F. oxysporium) Curvularia pallescence (C. pallescence). The antimicrobial activities have shown that upon complexation the activity increases.

  15. Synthesis and spectral characterization of Schiff base complexes of Cu(II), Co(II), Zn(II) and VO(IV) containing 4-(4-aminophenyl)morpholine derivatives: Antimicrobial evaluation and anticancer studies

    NASA Astrophysics Data System (ADS)

    Dhahagani, K.; Mathan Kumar, S.; Chakkaravarthi, G.; Anitha, K.; Rajesh, J.; Ramu, A.; Rajagopal, G.

    2014-01-01

    Metal(II) chelates of Schiff bases derived from the condensation of 4-morpholinoaniline with substituted salicylaldehyde have been prepared and characterized by 1H NMR, IR, electronic, EPR, and magnetic measurement studies. The complexes are of the type M(X-MPMP)2 [where M = Cu(II), Co(II)), Zn(II), or VO(IV); MPMP = 2-[(4 morpholinophenyl imino) methyl] 4-X-phenol, X = Cl, (L1H), X = Br (L2H)]. Single crystal X-ray crystallography studies confirm the structure of newly synthesized Schiff bases. The Schiff bases act as bidentate monobasic ligands, coordinating through deprotonated phenolic oxygen and azomethine nitrogen atoms. The free ligands and metal complexes are screened for their biopotency. Metal complexes exhibit better activity than ligands. Anticancer activity of ligands and their metal complexes are evaluated in human heptocarcinoma(HepG2) cells. The preliminary bioassay indicates that the Schiff base and its zinc complex exhibit inhibitory activity against the human gastric cancer cell lines.

  16. Dinuclear (Fe(II), Gd(III)) complexes deriving from hexadentate Schiff bases: synthesis, structure, and Mssbauer and magnetic properties.

    PubMed

    Costes, Jean-Pierre; Clemente-Juan, Juan Modesto; Dahan, Franoise; Dumestre, Frdric; Tuchagues, Jean-Pierre

    2002-06-01

    The dinuclear (Fe(II), Gd(III)) complexes studied in this report derive from hexadentate Schiff base ligands abbreviated H(2)L(i)() (i = 1, 2, 3). H(2)L(1) = N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2,2'-dimethyl-propane, H(2)L(2) = N,N'-bis(3-methoxysalicylidene)-1,2-diamino-2-methylpropane, and H(2)L(3) = N,N'-bis(3-methoxysalicylidene)-1,2-diaminoethane. The crystal and molecular structures of three complexes have been determined at 160 K. Depending on the solvent used in the preparation, L(1)Fe(CH(3)OH)Gd(NO(3))(3)(CH(3)OH)(2), 1, or L(1)Fe((CH(3))(2)CO)Gd(NO(3))(3), 1', is obtained from H(2)L(1). A similar complex, L(2)Fe((CH(3))(2)CO)Gd(NO(3))(3), 2, is obtained from H(2)L(2). Complex 1 crystallizes in the orthorhombic space group Pca2(1) (No. 29): a = 22.141(3) A, b = 9.4159(16) A, c = 15.2075(17) A, V = 3170.4(7) A(3), Z = 4. Complexes 1' and 2 crystallize in the monoclinic space group P2(1)/c (No. 14): 1', a = 9.6264(17) A, b = 19.662(3) A, c = 16.039(3) A, beta = 95.15(2) degrees, V = 3023.6(9) A(3), Z = 4; 2, a = 9.7821(13) A, b = 18.7725(17) A, c = 16.100(2) A, beta = 96.497(16) degrees, V = 2937.5(6) A(3), Z = 4. Complexes 1, 1', and 2 possess an Fe(O(phenoxo))(2-)Gd core. The mononuclear L(3)Fe complex could be prepared from H(2)L(3) but not the related dinuclear (Fe, Gd) species. Mssbauer spectroscopy evidences that the iron center is in the +2 oxidation state for the six complexes. The experimental magnetic susceptibility and magnetization data of complexes 1, 1', and 2 indicate the occurrence of weak Fe(II)-Gd(III) ferromagnetic interactions. Single ion zero-field splitting of the iron(II) must be taken into account for satisfactorily fitting the data by exact calculation of the energy levels associated to the spin Hamiltonian through diagonalization of the full matrix for axial symmetry (1, J = 0.50 cm(-1), D = 2.06 cm(-1); 1', J = 0.41 cm(-1), D = 3.22 cm(-1); 2, J = 0.08 cm(-1), D = 4.43 cm(-1)). PMID:12033896

  17. Synthesis, spectroscopic and biological activities studies of acyclic and macrocyclic mono and binuclear metal complexes containing a hard-soft Schiff base

    NASA Astrophysics Data System (ADS)

    Abou-Hussein, Azza A. A.; Linert, Wolfgang

    Mono- and bi-nuclear acyclic and macrocyclic complexes with hard-soft Schiff base, H2L, ligand derived from the reaction of 4,6-diacetylresorcinol and thiocabohydrazide, in the molar ratio 1:2 have been prepared. The H2L ligand reacts with Co(II), Ni(II), Cu(II), Zn(II), Mn(II) and UO2(VI) nitrates, VO(IV) sulfate and Ru(III) chloride to get acyclic binuclear complexes except for VO(IV) and Ru(III) which gave acyclic mono-nuclear complexes. Reaction of the acyclic mono-nuclear VO(IV) and Ru(III) complexes with 4,6-diacetylresorcinol afforded the corresponding macrocyclic mono-nuclear VO(IV) and Ru(IIII) complexes. Template reactions of the 4,6-diacetylresorcinol and thiocarbohydrazide with either VO(IV) or Ru(III) salts afforded the macrocyclic binuclear VO(IV) and Ru(III) complexes. The Schiff base, H2L, ligand acts as dibasic with two NSO-tridentate sites and can coordinate with two metal ions to form binuclear complexes after the deprotonation of the hydrogen atoms of the phenolic groups in all the complexes, except in the case of the acyclic mononuclear Ru(III) and VO(IV) complexes, where the Schiff base behaves as neutral tetradentate chelate with N2S2 donor atoms. The ligands and the metal complexes were characterized by elemental analysis, IR, UV-vis 1H-NMR, thermal gravimetric analysis (TGA) and ESR, as well as the measurements of conductivity and magnetic moments at room temperature. Electronic spectra and magnetic moments of the complexes indicate the geometries of the metal centers are either tetrahedral, square planar or octahedral. Kinetic and thermodynamic parameters were calculated using Coats-Redfern equation, for the different thermal decomposition steps of the complexes. The ligands and the metal complexes were screened for their antimicrobial activity against Staphylococcus aureus as Gram-positive bacteria, and Pseudomonas fluorescens as Gram-negative bacteria in addition to Fusarium oxysporum fungus. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

  18. Synthesis, spectroscopic characterization and antimicrobial activity of mono-, bi- and tri-nuclear metal complexes of a new Schiff base ligand

    NASA Astrophysics Data System (ADS)

    Shebl, Magdy; Khalil, Saied M. E.; Ahmed, Saleh A.; Medien, Hesham A. A.

    2010-09-01

    Condensation of o-acetoacetylphenol and 1,2-diaminopropane in 1:1 molar ratio under condition of high dilution yielded the mono-condensed dibasic Schiff base ligand with a N 2O 2 donors. The mono-condensed ligand has been used for further condensation with 2-hydroxy-5-nitrobenzaldehyde to obtain the new asymmetrical dicompartmental Schiff base ligand, H 3L, with N 2O 3 donors. The structure of the ligand was elucidated by analytical and spectroscopic tools (IR, 1H and 13C NMR spectra) which indicated that the coordinating sites are oxygen atoms of the phenolic OH groups, nitrogen atoms of the azomethine groups and the oxygen atom of the ketonic group. Reactions of the ligand with metal salts yielded mono- and homo-bi-nuclear complexes formulated as [M(HL)], where M dbnd Co(II), Ni(II) and Cu(II), [Fe(H 2L)Cl 2(H 2O)]?2H 2O, [Fe 2(HL)(ox)Cl 3(H 2O) 2]?5H 2O, [UO 2(H 2L)(OAc)(H 2O) 2], [VO(H 3L)(SO 4)(H 2O)]?H 2O, [M 2(L)Cl(H 2O) 2]?H 2O, where M dbnd Co(II) and Ni(II) and [Cu(H 2L)Cl]. The mononuclear Ni(II) complex, [Ni(HL)], was used to synthesize homo- and hetero-bi- and tri-nuclear complexes with the molecular formulae [Ni 2(L)Cl(H 2O) 2], [Ni 2(L) 2FeCl(H 2O)]?H 2O and [Ni 2(HL) 2CoCl 2]. The structures of the complexes were characterized by various techniques such as elemental and thermal analyses, IR, 1H and 13C NMR, mass and electronic spectra as well as conductivity and magnetic moment measurements. Square-planar and octahedral geometries are suggested for the Cu(II), Co(II) and Ni(II) complexes, octahedral geometry for the Fe(III) and VO 2+ complexes while uranium(VI) ion is octa-coordinated in its complex. The Schiff base and its metal complexes were evaluated for antimicrobial activity against Gram positive bacteria ( Staphylococcus aureus), Gram negative bacteria ( Escherichia coli) and fungi ( Candida albicans and Aspergillus flavus). The ligand and some of its complexes were found to be biologically active.

  19. Spectroscopy studies on Schiff base N,N?-bis(salicylidene)-1,2-phenylenediamine by NMR, infrared, Raman and DFT calculations

    NASA Astrophysics Data System (ADS)

    de Toledo, T. A.; Pizani, P. S.; da Silva, L. E.; Teixeira, A. M. R.; Freire, P. T. C.

    2015-10-01

    N,N?-bis(salicylidene)-1,2-phenylenediamine, also known as Salophen, is a Schiff base which crystallizes in monoclinic structure and space group P21/c, with four molecules per unit cell. It has been intensely studied in last decades because of its excellent properties with many potential applications. In the present study, the structural and vibrational properties of the Salophen were investigated combining scanning electronic microscopy (SEM), Raman, infrared, nuclear magnetic resonance (NMR) spectroscopy as experimental techniques and theoretical calculation based on density functional theory (DFT). The interpretation of the vibrational modes was carried out by means of potential energy distribution (PED). The theoretical results are in good agreement with experimental ones.

  20. Seven phenoxido-bridged complexes encapsulated by 8-hydroxyquinoline Schiff base derivatives and ?-diketone ligands: single-molecule magnet, magnetic refrigeration and luminescence properties.

    PubMed

    Wang, Shi-Yu; Wang, Wen-Min; Zhang, Hong-Xia; Shen, Hai-Yun; Jiang, Li; Cui, Jian-Zhong; Gao, Hong-Ling

    2016-02-16

    Seven dinuclear complexes based on 8-hydroxyquinoline Schiff base derivatives and ?-diketone ligands, [RE2(hfac)4L2] (RE = Y (), Gd (), Tb (), Dy (), Ho (), Er () and Lu (); hfac(-) = hexafluoroacetylacetonate; HL = 2-[(4-chloro-phenylimino)-methyl]-8-hydroxyquinoline), have been synthesized, and structurally and magnetically characterized. Complexes have similar dinuclear structures, in which each RE(III) ion is eight coordinated by two L(-) and two hfac(-) ligands in a distorted dodecahedron geometry. The luminescence spectra indicate that complex exhibits characteristic Tb(III) ion luminescence, while and show HL ligand luminescence. The magnetic studies reveal that features a magnetocaloric effect with the magnetic entropy change of -?Sm = 16.83 J kg(-1) K(-1) at 2 K for ?H = 8 T, and displays slow magnetic relaxation behavior with the anisotropic barrier of 6.7 K and pre-exponential factor ?0 = 5.3 10(-6) s. PMID:26792239