Note: This page contains sample records for the topic aromatic schiff base from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Mossbauer spectra of iron carbonyl complexes of aromatic azines and schiff bases  

SciTech Connect

An analysis is presented for the Mossbauer spectral data for a series of new iron carbonal complexes of aromatic azines and Schiff bases. The Mossbauer spectra were obtained on an electrodynamic instrument with a source consisting of Co 57 in chromium. The isomer shifts were related to the center of the sodium nitroprusside doublet. The nature of the substituents at the methylenimino group carbon a tom does not have a significant effect on the Mossbauer spectral parameters of binuclear complexes of iron with nitrogen bridges not containing a nitrogen-nitrogen bond. The ortho-metallated complexes obtained from Schiff bases and aromatic azines have two structurally nonequivalent iron atom positions.

Trusov, V.V.; Maksimov, Y.V.; Nekhaev, A.I.; Tyorin, V.D.

1986-02-01

2

Mossbauer spectra of iron carbonyl complexes of aromatic azines and schiff bases  

Microsoft Academic Search

An analysis is presented for the Mossbauer spectral data for a series of new iron carbonal complexes of aromatic azines and Schiff bases. The Mossbauer spectra were obtained on an electrodynamic instrument with a source consisting of Co 57 in chromium. The isomer shifts were related to the center of the sodium nitroprusside doublet. The nature of the substituents at

V. V. Trusov; Y. V. Maksimov; A. I. Nekhaev; V. D. Tyorin

1986-01-01

3

Synthesis, crystal structure and photoluminescent properties of an aromatic bridged Schiff base ligand and its zinc complex  

Microsoft Academic Search

An aromatic bridged Schiff base ligand, N,n?-bis((4,4?-diethylamino)salicylidene)-1,2-phenylenediamine (H2L3), and its trinuclear Zinc(II) complex, Zn3L23(CH3COO)2, were synthesized and characterized by means of elemental analyses, FT-IR and UV–Vis absorption spectra, and single crystal X-ray crystallography. The X-ray crystal structure of the complex reveals that the zinc ion (Zn1 or Zn1A) is coordinated by two oxygen atoms in phenolate and two nitrogen atoms

Tianzhi Yu; Kai Zhang; Yuling Zhao; Changhui Yang; Hui Zhang; Long Qian; Duowang Fan; Wenkui Dong; Lili Chen; Yongqing Qiu

2008-01-01

4

Complete ?* intramolecular aromatic hydroxylation mechanism through O2 activation by a Schiff base macrocyclic dicopper(I) complex.  

PubMed

In this work we analyze the whole molecular mechanism for intramolecular aromatic hydroxylation through O2 activation by a Schiff hexaazamacrocyclic dicopper(I) complex, [Cu(I) 2(bsH2m)](2+). Assisted by DFT calculations, we unravel the reaction pathway for the overall intramolecular aromatic hydroxylation, i.e., from the initial O2 reaction with the dicopper(I) species to first form a Cu(I)Cu(II)-superoxo species, the subsequent reaction with the second Cu(I) center to form a ?-?(2):?(2)-peroxo-Cu(II) 2 intermediate, the concerted peroxide O-O bond cleavage and C-O bond formation, followed finally by a proton transfer to an alpha aromatic carbon that immediately yields the product [Cu(II) 2(bsH2m-O)(?-OH)](2+). PMID:23616799

Poater, Albert; Solà, Miquel

2013-03-20

5

Complete ?* intramolecular aromatic hydroxylation mechanism through O2 activation by a Schiff base macrocyclic dicopper(I) complex  

PubMed Central

Summary In this work we analyze the whole molecular mechanism for intramolecular aromatic hydroxylation through O2 activation by a Schiff hexaazamacrocyclic dicopper(I) complex, [CuI 2(bsH2m)]2+. Assisted by DFT calculations, we unravel the reaction pathway for the overall intramolecular aromatic hydroxylation, i.e., from the initial O2 reaction with the dicopper(I) species to first form a CuICuII-superoxo species, the subsequent reaction with the second CuI center to form a ?-?2:?2-peroxo-CuII 2 intermediate, the concerted peroxide O–O bond cleavage and C–O bond formation, followed finally by a proton transfer to an alpha aromatic carbon that immediately yields the product [CuII 2(bsH2m-O)(?-OH)]2+.

Sola, Miquel

2013-01-01

6

Cytochrome P-450 dependent monooxygenases model system: rapid and efficient oxidation of primary aromatic amines to azo derivatives with sodium periodate catalyzed by manganese(III) Schiff base complexes.  

PubMed

Rapid and efficient oxidation of primary aromatic amines was investigated. Mn(III)-salophen catalyst can catalyze the oxidation of primary aromatic amines to azo derivatives with sodium periodate. The ability of various Schiff base complexes in this oxidation system was also investigated. PMID:15358293

Mirkhani, Valiollah; Tangestaninejad, Shahram; Moghadam, Majid; Moghbel, Maryam

2004-09-01

7

Preparation and characterisation of new oxovanadium(IV) Schiff base complexes derived from amino acids and aromatic o-hydroxyaldehydes  

Microsoft Academic Search

A range of mostly new oxovanadium(IV) complexes is described. They contain coordinated Schiff bases, made from natural amino acids (glycine, alanine, valine, leucine, isoleucine, methionine, phenylalanine, threonine, aspartic acid, and histidine) and salicylaldehyde or such derivatives as 3-, 4-, or 5-methoxy-salicylaldehyde. The coordination sphere is completed by simple ligands like water, 2,2?-bipyridyl or pyridine. The compounds are characterised and the

J. Costa Pessoa; I. Cavaco; I. Correia; M. T. Duarte; R. D. Gillard; R. T. Henriques; F. J. Higes; C. Madeira; I. Tomaz

1999-01-01

8

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

PubMed Central

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.

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

2006-01-01

9

Theoretical study on the excited-state intramolecular proton transfer in the aromatic schiff base salicylidene methylamine: an electronic structure and quantum dynamical approach.  

PubMed

The proton-transfer dynamics in the aromatic Schiff base salicylidene methylamine has been theoretically analyzed in the ground and first singlet (pi,pi) excited electronic states by density functional theory calculations and quantum wave-packet dynamics. The potential energies obtained through electronic calculations that use the time-dependent density functional theory formalism, which predict a barrierless excited-state intramolecular proton transfer, are fitted to a reduced three-dimensional potential energy surface. The time evolution in this surface is solved by means of the multiconfiguration time-dependent Hartree algorithm applied to solve the time-dependent Schrödinger equation. It is shown that the excited-state proton transfer occurs within 11 fs for hydrogen and 25 fs for deuterium, so that a large kinetic isotope effect is predicted. These results are compared to those of the only previous theoretical work published on this system [Zgierski, M. Z.; Grabowska, A. J. Chem. Phys. 2000, 113, 7845], reporting a configuration interaction singles barrier of 1.6 kcal mol(-1) and time reactions of 30 and 115 fs for the hydrogen and deuterium transfers, respectively, evaluated with the semiclassical instanton approach. PMID:16599431

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

2006-04-13

10

Heterocyclic Compounds from Schiff's Bases  

Microsoft Academic Search

BENZIMIDAZOLES have been prepared by oxidation of a mixture of an o-phenylene diamine and an aldehyde with cupric salts1 (for example, cupric acetate), and it has been pointed out2 that the reaction proceeds by the oxidative ring closure of the mono-Schiff's bases first obtained:

F. F. Stephens

1949-01-01

11

Synthesis, spectral, crystallography and thermal investigations of novel Schiff base complexes of manganese (III) derived from heterocyclic ?-diketone with aromatic and aliphatic diamine  

NASA Astrophysics Data System (ADS)

The Schiff base tetradentate ligands N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H 2L 1), N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-ethane-1,2-diamine (H 2L 2), N,N-bis-(3,5-dimethyl-1-p-tolyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H 2L 3) and N,N-bis-(3,5-dimethyl-1-p-sulfonyl-1H-pyrazol-4-ylmethylene)-benzene-1,2-diamine (H 2L 4) were prepared from the reaction between 5-oxo-3-methyl-1-p-tolyl-1H-pyrazole-4-carbaldehyde or 4-(4-formyl-5-oxo-3-methyl-pyrazol-1-yl)-benzenesulfonic acid and o-phenylenediamine or ethylenediamine. And these are characterized by elemental analysis, FT-IR, 1H NMR and GC-MS. The corresponding Schiff base complexes of Mn(III) were prepared by condensation of [Mn 3(? 3-O)(OAc) 6(H 2O) 3]·3H 2O with ligands H 2L 1, H 2L 2, H 2L 3 and H 2L 4. All these complexes have been characterized by elemental analysis, magnetic susceptibility, X-ray crystallography, conductometry measurement, FT-IR, electronic spectra and mass (FAB) spectrometry. Thermal behaviour of the complexes has been studied by TGA, DTA and DSC. Electronic spectra and magnetic susceptibility measurements indicate octahedral stereochemistry of manganese (III) complexes, while non-electrolytic behaviour complexes indicate the absence of counter ion.

Surati, Kiran R.; Thaker, B. T.

2010-01-01

12

REACTION OF LITHIUM-ALLYLPHOSPHONIC-BIS(DIMETHYLAMIDE) WITH SCHIFF BASES. TEMPERATURE AND STERIC EFFECT ON THE REGIOSELECTIVITY  

Microsoft Academic Search

The reaction of lithium-allylphosphonic-bis-(dimethylamide) 1 with aromatic Schiff bases 2a-e is studied. It is found that mainly mixtures of ? and ? adducts or, in some cases, only ? adducts are formed, the ratio ?:? depending on the reaction conditions as well as on the steric effect of the substituents in the Schiff base. In the most cases pure ?

Marko Kirilov; Jordanka Petrova; Zdravka Zdravkova

1985-01-01

13

Polymer-supported Schiff base complexes in oxidation reactions  

Microsoft Academic Search

Polymer-supported Schiff base complexes of metal ions show high catalytic activity in comparison to their unsupported analogues. The catalytic activity of metal complexes of different types of Schiff base was analyzed and presented in this review. The manganese(III) Schiff base complexes exhibited high catalytic activity in the oxidation of alkenes and alkanes both in homogeneous and heterogeneous conditions. Similarly, the

K. C. Gupta; Alekha Kumar Sutar; Chu-Chieh Lin

2009-01-01

14

Lubricants Containing a Schiff Base.  

National Technical Information Service (NTIS)

A corrosion and oxidation inhibitor for polyester lubricants employed in jet and rocket engines, diesels, and in transformer oils is a N,N'-dibenzylidenephenylenediamine compound having methylenedioxy radicals. Lubricant bases may be di- or polyesters of ...

K. L. McHugh J. O. Smith

1965-01-01

15

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

16

Factors determining tautomeric equilibria in Schiff bases  

NASA Astrophysics Data System (ADS)

Schiff bases derived from o-hydroxyaldehydes present keto and enol tautomeric forms; the relative equilibrium between these two tautomers depending on the particular aldehyde the Schiff bases is derived from. Thus benzaldehyde produces a stable enol tautomer, while a naphthaldehyde produces a mixture of keto and enol tautomers. The energy difference between these tautomers is very small (˜5 kJ/mol) and therefore close to current precision limits of ab initio and DFT based quantum calculations. NMR spectroscopy results, which allows for the determination of the stable structure when one tautomer is prevalent, can be very difficult to interpret when both tautomers are present. We calculate energy differences between the tautomers and demonstrate that the precision of current DFT calculations is not sufficient to predict the most stable structure. On the other hand, DFT calculations of the NMR chemical shifts (using the GIAO technique) can properly interpret the spectroscopy results allowing the characterization of the experimentally present tautomers and the estimation of the relative abundance of each when both are present.

Flores-Leonar, Martha; Esturau-Escofet, Nuria; Méndez-Stivalet, José M.; Marín-Becerra, Armando; Amador-Bedolla, Carlos

2011-12-01

17

Antibacterial and antifungal metal based triazole Schiff bases.  

PubMed

A new series of four biologically active triazole derived Schiff base ligands (L(1)-L(4)) and their cobalt(II), nickel(II), copper(II) and zinc(II) complexes (1-16) have been synthesized and characterized. The ligands were prepared by the condensation reaction of 3-amino-5-methylthio-1H-1,2,4-triazole with chloro-, bromo- and nitro-substituted 2-hydroxybenzaldehyde in an equimolar ratio. The antibacterial and antifungal bioactivity data showed the metal(II) complexes to be more potent antibacterial and antifungal than the parent Schiff bases against one or more bacterial and fungal species. PMID:22803673

Chohan, Zahid H; Hanif, Muhammad

2012-07-18

18

Structuring Redox Polymers Poly[M(Schiff)] (M = Ni, Pd; Schiff = Schiff Bases) on a Molecular Level: Methods and Results of an Investigation  

Microsoft Academic Search

This work is devoted to a consideration of methods of electrochemical synthesis of redox polymers poly[M(Schiff)], where “M” is Ni, or Pd and “Schiff” stands for a four-dentate Schiff base, with a controlled distribution of structural elements (stacks) over the electrode's surface for the optimization of the transport of charge-compensating ions, which is the stage that determines the charge transfer

T. Yu. Rodyagina; P. V. Gaman'kov; E. A. Dmitrieva; I. A. Chepurnaya; S. V. Vasil'eva; A. M. Timonov

2005-01-01

19

Corrosion inhibition of mild steel by schiff base compounds in various aqueous solutions: part 1  

Microsoft Academic Search

The corrosion inhibition by Schiff base compounds derived from diamines and o-hydroxy, o-methoxy aromatic aldehydes was investigated by weight loss, electrochemical measurements and surface analysis of SS 400 in various aqueous solutions such as tap water (LC), concentrated tap water (HC) and HCl solutions. The maximum inhibition efficiency (?) of N,N?-bis (salicylaldehyde)-1,12-diaminododecane (Saldn) for SS 400 in HCl solution approached

H Shokry; M Yuasa; I Sekine; R. M Issa; H. Y El-baradie; G. K Gomma

1998-01-01

20

Microwave-Induced Synthesis of Schiff Bases of Aminothiazolyl Bromocoumarins as Antibacterials  

PubMed Central

A fast and highly efficient method for the synthesis of some of the schiff bases of aminothiazolylbromocoumarin (4a-m) has been performed by microwave irradiation of 2?-amino-4?-(6-bromo-3-coumarinyl) thiazole (3) and substituted aromatic aldehydes (a-m). Microwave assisted reactions have resulted in better yields of the desired products than when prepared under conventional conditions. The resulting products were evaluated for their qualitative and quantitative antibacterial activity.

Venugopala, K. N.; Jayashree, B. S.

2008-01-01

21

Reduction of Schiff's Bases and Phenylhydrazones by Zinc Dust  

Microsoft Academic Search

Schiff's bases when subjected to the chemical action of zinc dust and chloroform in ethyl alcohol at steam bath temperature for varying times yield 1,2-diaminophenylethanes in crystalline form and in good yield (Table 1).

Naseem H. Khan; Rashid K. Zuberi; Amin A. Siddiqui

1980-01-01

22

Ruthenium(II) carbonyl complexes containing tridentate Schiff bases  

Microsoft Academic Search

New ruthenium(II) complexes, [Ru(CO)(B)(LL')(PPh3)] (where, LL' = tridentate Schiff bases; B = PPh3, pyridine, piperidine or morpholine) have been prepared by reacting [RuHCl(CO)(PPh3)3] or [RuHCl(CO)(PPh3)2(B)] with Schiff bases containing donor groups (O, N, X) viz., salicylaldehyde thiosemicarbazone (X = S), salicylaldehyde semicarbazone (X = O), o-hydroxyacetophenone thiosemicarbazone (X = S) and o-hydroxyacetophenone semicarbazone (X = O). The new complexes were

Thangaian D. Thangadurai; Karuppannan Natarajan

2002-01-01

23

On Schiff's bases and aldehyde-fuchsin: A review from H. Schiff to R.D. Lillie  

Microsoft Academic Search

In histochemistry aldehyde-fuchsin is widely regarded as an azomethine compound, though this hypothesis cannot explain the variety of reaction products. Infrared spectroscopy did not show a C=N bond. It was therefore deemed of interest to review chemical studies of aldehydefuchsin and other Schiff's bases by Schiff and his contemporaries. Schiff regarded reaction products of low molecular aliphatic aldehydes, e.g. acetaldehyde,

H. Puchtler; S. N. Meloan

1981-01-01

24

A Schiff base connectivity switch in sensory rhodopsin signaling.  

PubMed

Sensory rhodopsin I (SRI) in Halobacterium salinarum acts as a receptor for single-quantum attractant and two-quantum repellent phototaxis, transmitting light stimuli via its bound transducer HtrI. Signal-inverting mutations in the SRI-HtrI complex reverse the single-quantum response from attractant to repellent. Fast intramolecular charge movements reported here reveal that the unphotolyzed SRI-HtrI complex exists in two conformational states, which differ by their connection of the retinylidene Schiff base in the SRI photoactive site to inner or outer half-channels. In single-quantum photochemical reactions, the conformer with the Schiff base connected to the cytoplasmic (CP) half-channel generates an attractant signal, whereas the conformer with the Schiff base connected to the extracellular (EC) half-channel generates a repellent signal. In the wild-type complex the conformer equilibrium is poised strongly in favor of that with CP-accessible Schiff base. Signal-inverting mutations shift the equilibrium in favor of the EC-accessible Schiff base form, and suppressor mutations shift the equilibrium back toward the CP-accessible Schiff base form, restoring the wild-type phenotype. Our data show that the sign of the behavioral response directly correlates with the state of the connectivity switch, not with the direction of proton movements or changes in acceptor pK(a). These findings identify a shared fundamental process in the mechanisms of transport and signaling by the rhodopsin family. Furthermore, the effects of mutations in the HtrI subunit of the complex on SRI Schiff base connectivity indicate that the two proteins are tightly coupled to form a single unit that undergoes a concerted conformational transition. PMID:18852467

Sineshchekov, Oleg A; Sasaki, Jun; Phillips, Brian J; Spudich, John L

2008-10-13

25

Solvent-free Mechanosynthesis of Two Thermochromic Schiff Bases.  

PubMed

Two thermochromic Schiff bases mostly in keto-amine tautomeric form were obtained by means of mechanochemical synthesis. Both Schiff bases Compound 1 and Compound 2, respectively are derived from the same primary amine 2-amino-5-methylphenol. Salicylaldehyde was used as aldehyde component in preparation of 1, and o-vanillin as substituted salicylaldehyde component in synthesis of 2. Powder products of the neat grinding and liquid-assisted grinding syntheses of 1 and 2 were compared with the crystalline products, obtained by recrystallization from a small amount of solvent. Both raw powder and recrystallized products were characterized and compared by means of PXRD, DSC and IR. PMID:24061325

Kaitner, Branko; Zba?nik, Marija

2012-09-01

26

Chromium, Molybdenum and Ruthenium Complexes of 2Hydroxyacetophenone Schiff Bases  

Microsoft Academic Search

Interaction of the Schiff base 2-hydroxyacetophenonepropylimine (happramH) with M(CO)6, M=Cr or Mo under reduced pressure gave the dicarbonyl complex M(CO)2(happramH)2. The complex MoO(happram)2 was isolated from the reaction of Mo(CO)6 and happramH in air. Ru3(CO)12 and RuCl3 reacted with the Schiff base bis-(2-hydroxyacetophenone)ethylenediimine (hapenH2) to give Ru(CO)2(hapenH2) and [RuCl2(hapenH2)]Cl. Elemental, spectroscopic and magnetic studies of the reported complexes revealed the

S. A. Ali; A. A. Soliman; M. M. Aboaly; R. M. Ramadan

2002-01-01

27

Adsorption behaviour of Schiff base and corrosion protection of resulting films to copper substrate  

Microsoft Academic Search

Self-assembled (SA) films of Schiff base were prepared on the copper surface. The corrosion protection abilities of SA films in chloride solution were evaluated using electrochemical impedance spectroscopy and polarization curves. A subsequent adsorption of 1-dodecanethiol on the original SA films of Schiff base improved significantly the protection ability to the copper substrate. The behavior of Schiff base adsorption on

Zhenlan Quan; Shenhao Chen; Ying Li; Xuegui Cui

2002-01-01

28

Synthesis and spectroscopic properties of novel asymmetric Schiff bases.  

PubMed

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

Güngör, Ozlem; Gürkan, Perihan

2010-05-24

29

[Schiff base type onno spectrophotometric determination of magnesium].  

PubMed

By condensing hydrazide salicylic acid with o-hydroxy carbonilic compounds it was obtained 2--hydroxy acetophenon--salicyl hidrazina, Schiff base--type ONNO. These Schiff bis bases present a good capacity of complexing the Mg (II) ions. The above mentioned Schiff base forms complex with Mg (II) cation, with maximum absorbance at 386 nm, and molar absorbtivity (epsilon) = 6.27 x 10(4) mol-1.L.cm-1. The complex with Mg (II) presents a maximum stability at pH = 9.6 - 10.0. The calculated apparent stability constant is K = 3.18 x 10(3). The absorbance is proportional to Mg (II) concentration in the range of 10-60 mg/mL. In this range, the Lambert--Beer law is respected, the linearity coefficient being 0.9818, SD = 0.83, RSD = 0.84 (n = 6). The results obtained for spectrophotometric determination of Mg (II) using this Schiff base as reagent were successfully applied to pharmaceutical products containing Mg (II) cation. PMID:14756002

Tântaru, Gladiola; Bibire, Nela; Dorneanu, V; Stan, Maria

30

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

PubMed

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, (1)H, (13)C and (31)P 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. PMID:21924947

Manikandan, R; Viswanathamurthi, P; Muthukumar, M

2011-08-27

31

Primordial transport of sugars and amino acids via Schiff bases  

NASA Astrophysics Data System (ADS)

Experimental support is given for a model concerning the origin of a primordial transport system. The model is based on the facilitated diffusion of amino acids stimulated by aliphatic aldehyde carriers and sugars stimulated by aliphatic amine carriers. The lipid-soluble diffusing species is the Schiff base. The possible role of this simple transport system in the origin of an early protocell is discussed.

Stillwell, William; Rau, Aruna

1981-09-01

32

Electrospray ionization mass spectral fragmentation study of amino acid derived oxovanadium Schiff base complexes and (oxo)-peroxovanadium Schiff base complexes  

NASA Astrophysics Data System (ADS)

Amino acid derived oxovanadium Schiff base complexes and their in situ (oxo)-peroxovanadium Schiff base complexes were first studied with electrospray ionization tandem mass spectrometry (ESI-MSn) with collision-induced dissociation (CID). Their fragmentation pathways are proposed on the base of the MSn studies. All of the molecular ions of the two group vanadium complexes easily lose a CO2 molecule under ESI-MS condition. In the dissociation, H2O, VO2 will possibly be eliminated for oxovanadium Schiff base complexes, while (oxo)-peroxovanadium Schiff base complexes always yield the same ion at m/z 314 due to elimination of a molecule of aldehyde from amino acid residues. The dissociation rules may be extended to other metal Schiff base complexes and other peroxo-metal complexes.

Zeng, Qing-Le; Chen, Wei-Zhu; Zhao, Yu-Fen

2007-04-01

33

Construction of a novel Zn-Ni trinuclear Schiff base and a Ni2+ chemosensor.  

PubMed

A novel Zn-Ni heterotrinuclear Schiff base compound bearing acacen(2-) moieties was constructed through the selective assembly of a chemosensor Schiff base zinc compound with a Ni(2+) ion. Its crystal structure not only clearly explains the binding mode between the chemosensor molecule and the detected metal ion but also represents the first trinuclear complex based on a symmetric acacen(2-) base Schiff base. PMID:20690735

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

2010-08-16

34

Synthesis of Schiff bases of naphtha[1,2-d]thiazol-2-amine and metal complexes of 2-(2?-hydroxy)benzylideneaminonaphthothiazole as potential antimicrobial agents  

PubMed Central

Objective: A series of 2-benzylideneaminonaphthothiazoles were designed and synthesized incorporating the lipophilic naphthalene ring to render them more capable of penetrating various biomembranes. Methods: Schiff bases were synthesized by the reaction of naphtha[1,2-d]thiazol-2-amine with various substituted aromatic aldehydes. 2-(2?-Hydroxy)benzylideneaminonaphthothiazole was converted to its Co(II), Ni(II) and Cu(II) metal complexes upon treatment with metal salts in ethanol. All the compounds were evaluated for their antibacterial activities by paper disc diffusion method with Gram positive Staphylococcus aureus and Staphylococcus epidermidis and Gram negative Escherichia coli and Pseudomonas aeruginosa bacteria. The minimum inhibitory concentrations of all the Schiff bases and metal complexes were determined by agar streak dilution method. Results: All the compounds moderately inhibited the growth of Gram positive and Gram negative bacteria. In the present study among all Schiff bases 2-(2?-hydroxy)benzylideneaminonaphthothiazole showed maximum inhibitory activity and among metal complexes Cu(II) metal complex was found to be most potent. Conclusion: The results obtained validate the hypothesis that Schiff bases having substitution with halogens, hydroxyl group and nitro group at phenyl ring are required for the antibacterial activity while methoxy group at different positions in the aromatic ring has minimal role in the inhibitory activity. The results also indicated that the metal complexes are better antibacterial agents as compared to the Schiff bases.

Azam, Faizul; Singh, Satendra; Khokhra, Sukhbir Lal; Prakash, Om

2007-01-01

35

Palladium(II) Schiff base complexes derived from sulfanilamides and aminobenzothiazoles  

Microsoft Academic Search

Schiff bases (HL) derived from sulfanilamides or aminobenzothiazoles add to Pd(OAc)2 to give complexes of the type PdL2(1–7) in moderate to excellent yields. Reactions of Schiff bases containing pyrimidine groups, however, gave several products arising from competing coordination of the pyrimidine nitrogen. Palladium complexes and Schiff bases have been investigated as antifungal agents against Aspergillus niger and Aspergillus flavus.

Robin R. Coombs; Melissa K. Ringer; Johanna M. Blacquiere; Joshua C. Smith; J. Scott. Neilsen; Yoon-Seo Uh; J. Bryson. Gilbert; Lisa J. Leger; Haiwen Zhang; Alison M. Irving; Susan L. Wheaton; Christopher M. Vogels; Stephen A. Westcott; Andreas Decken; Felix J. Baerlocher

2005-01-01

36

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

Microsoft Academic Search

An octahedral ruthenium(III) Schiff base complexes of the type [RuX(EPh3)(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 [RuX3(EPh3)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

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

2009-01-01

37

[Synthesis and spectral characteristics of novel di-schiff base derivatives incorporting oxadiazole ring].  

PubMed

4-nitrobenzoic acid and hydraxine sulfate were cyclized with H3PO4/P2O5 to afford 2,5-bis(4-nitrophenyl)-1, 3,4-oxadiazole(1), then(1)was reduced to 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole using Zn/CaCl2 as reduction reagent, and at last, a series of novel di-schiff base derivatives containing oxadiazole ring were obtained by the reaction of 2,5-bis(4-aminophenyl)-1, 3,4-oxadiazole with aromatic aldehydes (yield: 65%-81%). The structures of these compounds were confirmed by 1H NMR, FTIR and MS. Their UV-Vis spectra as well as fluorescence spectra were studied and the electrochemical properties were tested with cyclic voltammetry. The UV-Vis spectroscopy results show that the characteristic absorption peaks of 1, 3, 4-oxadiazole unit and di-schiff base unit disappeared. The maximum absorption wavelength was detected at 345-357 nm because conjugation effect made the two energy bands partially hybrid and form a new energy band structure. Fluorescence spectroscopy results show that they emit strong blue and purple fluorescence, and the emission maximum wavelengths of di-schiff base are from 390 to 407 nm. Electrochemical properties results show that they have higher affinity energy (2.36-3.04 eV) and ionic potential (5.35-6.06 eV), which indicated that they have better electron-transporting properties than PBD except 3 a and 3 h. The results give a reference to further application to organic electroluminescent devices of the target compound. PMID:19248511

Chen, Tong-bin; Zhang, Xiong-lu; Fan, Xiao-lin; Li, Xun

2008-12-01

38

Synthesis and AntiBacterial\\/Catalytic Properties of Schiff Bases and Schiff Base Metal Complexes Derived from 2,3-Diaminopyridine  

Microsoft Academic Search

Two new Schiff bases (1a)-(2a) derived from 2,3-diaminopyridine (DAPY) with pyrrole-2-carboxaldehyde (Pyrr) and 2-hydroxy-1-naphthaldehyde (NaphH), and new copper(II), iron(III), nickel(II), ruthenium(II) and zinc(II) complexes (1b)-(1e), (2b)-(2f) and (3b)-(3d) derived from these two new Schiff bases, and the bis-condensed Schiff base of 2,3-diaminopyridine and salicylaldehyde (SalH) were synthesized. They were characterized by a combination of elemental analyses, magnetic susceptibility measurements, IR

T. Jeewoth; H. Li Kam Wah; Minu G. Bhowon; D. Ghoorohoo; K. Babooram

2000-01-01

39

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

NASA Astrophysics Data System (ADS)

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(?4-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(?4-O) cores.

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

2013-06-01

40

Copper(II) selective electrochemical sensor based on Schiff Base complexes  

Microsoft Academic Search

Plasticized membranes using Schiff Base complexes, derived from 2,3-diaminopyridine and o-vanilin have been prepared and explored as Cu2+-selective sensors. Effect of various plasticizers viz., dibutyl phthalate (DBP), dioctylphthalate (DOP), chloronaphthalene (CN), tri-n-butylphosphate (TBP) etc. and anion excluder, sodium tetraphenylborate (NaTPB) was studied in detail and improved performance was observed at several instances. Optimum performance was observed with Schiff Base (B)

Lok P. Singh; Jitendra M. Bhatnagar

2004-01-01

41

Synthesis of new Schiff bases containing thiophene moiety  

Microsoft Academic Search

Seven new Schiff bases, which are 4,4,4-trifluorol-(2-thienyl)-l-butanone-3-Z, Z=-thiosemicarbazone (a); -thiocarbohydrazone (b),-benzoic hydrazone (c), -(o-hydroxyphenyl) imine (d) ,-nicotinic hydrazone (e) ,-salicylic hydrazone (f), and -(p-fluoro-m-chlorophenyl) imine (g), have been synthesized by reaction of 4, 4, 4-trifluoro-1-(2-thienyl)-l, 3-butanedione (TFTBD) with corresponding hydrazides\\u000a or anilines, acetic acid orp-toluence sulfonic acid as catalyst, and characterized by Elemental analysis, IR, UV-Vis.1H NMR and MS. The

Zhu Wan-ren; Hu Pei-zhi; Li Mei-ying; Huang Xiao-ling; Wu Cheng-tai

2003-01-01

42

Synthesis, characterization, and biological studies of some Schiff base complexes  

Microsoft Academic Search

The synthesis of a new Schiff base derived from 2-hydroxy-5-chloroacetophenone and 4-amino-5-mercapto-3-methyl-1,2,4-triazole\\u000a and its coordination compounds with Ti(III), VO(IV), Cr(III), Mn(III), Fe(III), Zr(IV), MoO2(VI), and UO2(VI) are described. The ligand and the complexes have been characterized on the basis of analytical, electrical conductance,\\u000a molecular weight, IR and electronic spectra, magnetic susceptibility measurements, and thermogravimetric analysis. The ligand\\u000a acts as a

V. B. Badwaik; A. S. Aswar

2007-01-01

43

Amino acid-containing reduced Schiff bases as the building blocks for metallasupramolecular structures  

Microsoft Academic Search

Metal coordination compounds derived from several closely related yet different multidentate reduced Schiff base ligands (obtained by reducing the CN bond in the Schiff bases formed by the condensation of aldehyde and various natural\\/unnatural amino acids) are discussed in terms of their mode of binding and coordination to supramolecular network structures. These multidentate ligands have flexible backbone with hydrogen bond

Rakesh Ganguly; Bellam Sreenivasulu; Jagadese J. Vittal

2008-01-01

44

Controlling the pKa of the bacteriorhodopsin Schiff base by use of artificial retinal analogues  

SciTech Connect

Artificial bacteriorhodopsin pigments based on synthetic retinal analogues carrying an electron-withdrawing CF3 substituent group were prepared. The effects of CF3 on the spectra, photocycles, and Schiff base pKa values of the pigments were analyzed. A reduction of 5 units in the pKa of the Schiff base is observed when the CF3 substituent is located at the C-13 polyene position, in the vicinity of the protonated Schiff base nitrogen. The results lead to the unambiguous characterization of the (direct) titration of the Schiff base in bacteriorhodopsin and to the conclusion that the deprotonation rate of the Schiff base during the photocycle (i.e., the generation of the M412 intermediate) is determined by a structural change in the protein.

Sheves, M.; Albeck, A.; Friedman, N.; Ottolenghi, M.

1986-05-01

45

Synthesis, characterization, and spectroscopic investigation of benzoxazole conjugated Schiff bases.  

PubMed

Two Schiff bases were synthesized by reaction of 2-(4'-aminophenyl)benzoxazole derivatives with 4-N,N-diethylaminobenzaldehyde. UV-visible (UV-vis) and steady-state fluorescence in solution were applied in order to characterize its photophysical behavior. The Schiff bases present absorption in the UV region with fluorescence emission in the blue-green region, with a large Stokes' shift. The UV-vis data indicates that each dye behaves as two different chromophores in solution in the ground state. The fluorescence emission spectra of the dye 5a show that an intramolecular proton transfer (ESIPT) mechanism takes place in the excited state, whereas a twisted internal charge transfer (TICT) state is observed for the dye 5b. Theoretical calculations were performed in order to study the conformation and polarity of the molecules at their ground and excited electronic states. Using density functional theory (DFT) methods at theoretical levels BLYP/Aug-SV(P) for geometry optimizations and B3LYP/6-311++G(2d,p) for single-point energy evaluations, the calculations indicate that the lowest energy conformations are in all cases nonplanar and that the dipole moments of the excited state relaxed structures are much larger than those of the ground state structures, which corroborates the experimental UV-vis absorption results. PMID:21988352

Santos, Fabiano S; Costa, Tania M H; Stefani, Valter; Gonçalves, Paulo F B; Descalzo, Rodrigo R; Benvenutti, Edilson V; Rodembusch, Fabiano S

2011-10-27

46

Schiff bases as potential fungicides and nitrification inhibitors.  

PubMed

A number of substituted Schiff bases were synthesized and characterized by (1)H NMR and mass spectrometry. These compounds were screened for antifungal activity in vitro against pathogenic fungi, namely, Sclerotium rolfsii and Rhizoctonia bataticola, and for their effect on nitrification inhibition under laboratory conditions. Maximum antifungal activity was exhibited by (2,4-dichlorobenzylidene)-(2,4,5-trichlorophenyl)-amine and (3-nitrobenzylidene)-(2,4,5-trichlorophenyl)-amine against both fungi (ED(50) with range from 3 to 24 microg/mL). Maximum nitrification inhibition (NI) was exhibited by (2,4-dichlorobenzylidene)-(2-fluorophenyl)-amine, (4-fluorophenyl)-(3-nitrobenzylidene)-amine, (2,6-dichlorobenzylidene)-(4-fluorophenyl)-amine, and (2,6-dichlorobenzylidene)-(3 fluorophenyl)-amine (NI in the range 91-96%). PMID:19702271

Aggarwal, Nisha; Kumar, Rajesh; Dureja, Prem; Rawat, Diwan S

2009-09-23

47

Investigation on some Schiff bases as HCl corrosion inhibitors for carbon steel  

Microsoft Academic Search

Potentiodynamic polarisation and ac impedance studies were carried out on the inhibition of carbon steel in 0.1M hydrochloric acid solution by various Schiff bases containing heteroaromatic substituents. The examined Schiff bases were 2-((1E)-2-aza-2-pyrimidine-2-ylvinyl)thiophene, 2-((1Z)-1-aza-2-(2-pyridyl)vinyl)pyrimidine, 2-((1E)-2-aza-2-(1,3-thiazol-2-yl)vinyl)thiophene, 2-((1Z)-1-aza-2-(2-thienyl)vinyl)benzothiazole. Polarisation curves indicates that studied Schiff bases act essentially as anodic inhibitor. The variation in inhibitive efficiency mainly depends on the type and nature

A. Yurt; A. Balaban; S. Ustün Kandemir; G. Bereket; B. Erk

2004-01-01

48

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

Microsoft Academic Search

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 1M 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 0.01M Schiff base A. Results show

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

2006-01-01

49

Inhibition of copper corrosion by several Schiff bases in aerated halide solutions  

Microsoft Academic Search

The inhibitive action of three Schiff bases, N,N'-o-phenylen-bis(3-methoxysalicylidenimine) (V–o-Ph–V), N,N'-p-phenylen-bis (3-methoxysalicylidenimine) (V–p-Ph–V) and N-[(2-hydroxy-3-methoxyphenyl)methylene]-histidine (V-His), on copper corrosion in aerated 0.5 mol dm-3 NaCl and NaBr solutions was investigated using EIS and steady-state polarization techniques. The inhibitor effectiveness depended strongly on the geometric structure of the Schiff bases. Among the three kinds of Schiff base used, the inhibition efficiency of

H. Ma; S. Chen; L. Niu; S. Zhao; S. Li; D. Li

2002-01-01

50

Catalytic activities and properties of Au(III)\\/Schiff-base complexes in methanol oxidative carbonylation  

Microsoft Academic Search

Several Au(III)\\/Schiff-base complexes were studied and proven to be effective catalysts for oxidative carbonylation of methanol to generate dimethyl carbonate (DMC). Effects of Schiff-base ligands, promoters, and promoter mole ratio to Au(III)\\/Schiff-base complexes on catalytic activity were studied. When the reaction was carried out at a methanol\\/Au(III) molar ratio of 5060:1, an [AuCl2(phen)]Cl\\/KI (phen=1,10-phenanthroline) ratio of 1:4, a CO\\/O2 pressure

Jinjin Li; Jianglin Hu; Yanlong Gu; Fuming Mei; Tao Li; Guangxing Li

2011-01-01

51

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

NASA Astrophysics Data System (ADS)

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.

Suvetha Rani, J.; Ramakrishnan, V.

2013-10-01

52

pKa of the protonated Schiff base of bovine rhodopsin. A study with artificial pigments.  

PubMed Central

Artificial bovine rhodopsin pigments derived from synthetic retinal analogues carrying electron-withdrawing substituents (fluorine and chlorine) were prepared. The effects of the electron withdrawing substituents on the pKa values of the pigments and on the corresponding Schiff bases in solution were analyzed. The data suggest that the apparent pKa of the protonated Schiff base is above 16. However, the alternative possibility that the retinal Schiff base linkage in bovine rhodopsin is not accessible for titration from the aqueous bulk medium cannot be definitely ruled out.

Steinberg, G; Ottolenghi, M; Sheves, M

1993-01-01

53

Optical pH sensor based on spectral response of newly synthesized Schiff bases  

Microsoft Academic Search

In most of the common designs, pH optodes rely on weak acidic dyes whose dissociated and undissociated forms have different absorption or emission maximums. In this work the newly synthesized Schiff bases; N,N?-bis(4-diaminobenzyliden)-1,2-cyclohexandiamine [I], N,N?-bis(4-diaminobenzyliden)-1,2-ethanediamine [II] and 2,6-bis[(4-dimethylaminophenylimino)ethyl]pyridine [III], have been used for pH sensing in four different plasticized PVC matrices. The Schiff bases exhibited absorption and emission based optical

Cemal Hazneci; Kadriye Ertekin; Berrin Yenigul; Engin Cetinkaya

2004-01-01

54

Coordination Compounds of Rare Earth Chlorides with the Schiff Base Derived from Vanillin and 2Naphthylamine  

Microsoft Academic Search

Coordination compounds of rare earth chlorides with Schiff base derived from vanillin (3-methoxy-4-hydroxy-benzaldehyde) and 2-naphthylamine have been prepared and characterized. The general formula of the coordination compounds, [LnL2Cl2(H20)2] Cl H20 (where Ln - La, Ce, Pr, Nd, Eu, Gd, Dy, Ho, Tm, Lu; L = Schiff base), are based on the elemental analyses, infrared spectra, ultraviolet spectra, Raman Spectra, Molar

Liu Guofa; Zhao Yongnian; Cao Xizhang

1992-01-01

55

Tuning of spin crossover behaviour in iron(III) complexes involving pentadentate Schiff bases and pseudohalides.  

PubMed

Investigations on a series of eight novel mononuclear iron(III) Schiff base complexes with the general formula [Fe(L(5))(L(1))]·S (where H(2)L(5) = pentadentate Schiff-base ligand, L(1) = a pseudohalido ligand, and S is a solvent molecule) are reported. Several different aromatic 2-hydroxyaldehyde derivatives were used in combination with a non-symmetrical triamine 1,6-diamino-4-azahexane to synthesize the H(2)L(5) Schiff base ligands. The consecutive reaction with iron(III) chloride resulted in the preparation of the [Fe(L(5))Cl] precursor complexes which were left to react with a wide range of the L(1) pseudohalido ligands. The low-spin compounds were prepared using the cyanido ligand: [Fe(3m-salpet)(CN)]·CH(3)OH (1a), [Fe(3e-salpet)(CN)]·H(2)O (1b), while the high-spin compounds were obtained by the reaction of the pseudohalido (other than cyanido) ligands with the [Fe(L(5))Cl] complex arising from salicylaldehyde derivatives: [Fe(3Bu5Me-salpet)(NCS)] (2a), [Fe(3m-salpet)(NCO)]·CH(3)OH (2b) and [Fe(3m-salpet)(N(3))] (2c). The compounds exhibiting spin-crossover phenomena were prepared only when L(5) arose from 2-hydroxy-1-naphthaldehyde (H(2)L(5) = H(2)napet): [Fe(napet)(NCS)]·CH(3)CN (3a, T(1/2) = 151 K), [Fe(napet)(NCSe)]·CH(3)CN (3b, T(1/2) = 170 K), [Fe(napet)(NCO)] (3c, T(1/2) = 155 K) and [Fe(napet)(N(3))], which, moreover, exhibits thermal hysteresis (3d, T(1/2)? = 122 K, T(1/2)? = 117 K). These compounds are the first examples of octahedral iron(III) spin-crossover compounds with the coordinated pseudohalides. We report the structure and magnetic properties of these complexes. The magnetic data of all the compounds were analysed using the spin Hamiltonian formalism including the ZFS term and in the case of spin-crossover, the Ising-like model was also applied. PMID:21904754

Nemec, Ivan; Herchel, Radovan; Bo?a, Roman; Trávní?ek, Zden?k; Svoboda, Ingrid; Fuess, Hartmut; Linert, Wolfgang

2011-09-09

56

Synthesis and Characterization of Novel Crude Oil Dispersants Based on Ethoxylated Schiff Base  

Microsoft Academic Search

Schiff base prepared from salicylaldehyde and diethylene triamine was ethoxylated by poly (ethylene glycol) of different molecular weights, namely 200, 600, 1000 and 2000, by using ?,?-dichlorodiethyl ether as a linking agent. The ethoxylation reaction took place at both ends of the base upon using poly(ethylene glycol) (PEG) 200 and 600, whereas at one end when PEG 1000 and 2000

Shimaa M. El-Saeed; Reem K. Farag; Manar E. Abdul-Raouf; Abdel-Azim A. Abdel-Azim

2008-01-01

57

Dissolution behavior of porcine somatotropin with simultaneous gel formation and lysine Schiff-base hydrolysis  

Microsoft Academic Search

The primary goal of this work was to develop a reliable in vitro dissolution model to evaluate the effects of Schiff-base hydrolysis and gel formation on the dissolution kinetics of pellets of porcine somatotropin (pST) and pST conjugated with ortho-vanillin (ov-pST) via Schiff-base formation, in an effort to develop an extended-release pST implant. Experimentally, dissolution was investigated as a function

Christopher J Roberts; Qin Ji; Liling Zhang; Richard T Darrington

2001-01-01

58

Synthesis, characterization and catalytic studies of ruthenium(II) Schiff base complexes  

Microsoft Academic Search

Complexes of the type [Ru(CO)(EPh3)(B)(L)] (E = P or As; B = PPh3, AsPh3, py or pip; L = dianion of the Schiff bases derived from the condensation of salicyloyl hydrazide with acetone, ethyl methyl ketone and salicylaldehyde have been synthesised by the reaction of equimolar amounts of [RuHCl(CO)(EPh3)2(B)] and Schiff bases in benzene. The resulting complexes have been characterized

Sivasamy Kanchanadevi; Kugalur P. Balasubramanian; Vaiyapuri Chinnusamy; Ramasamy Karvembu; Karuppannan Natarajan

2005-01-01

59

Complexes of a tridentate ONS Schiff base. Synthesis and biological properties  

Microsoft Academic Search

Several new complexes of a tridentate ONS Schiff base derived from the condensation of S-benzyldithiocarbazate with salicylaldehyde have been characterised by elemental analyses, molar conductivity measurements\\u000a and by i.r. and electronic spectra. The Schiff base (HONSH) behaves as a dinegatively charged ligand coordinating through\\u000a the thiolo sulphur, the azomethine nitrogen and the hydroxyl oxygen. It forms mono-ligand complexes: [M(ONS)X], [M=NiII,

M. Tofazzal H. Tarafder; Manaf A. Ali; D. Juan Wee; Kasbollah Azahari; Sidik Silong; Karen A. Crouse

2000-01-01

60

Coordination Compounds of Rare Earth Nitrate with Schiff Base Derived from Vanillin and 2Naphthylamine  

Microsoft Academic Search

New coordination coapounds of rare earth nitrates with Schiff base derived from vanillin (3-methoxy-4-hydroxy-benzaldehyde) and 2-naphthylanine having the general formula [LnL2(N03)2] NO3 (where Ln = La, Nd, Sm, Eu, Tb, Dy, Er, Yb, Lu; L = Schiff base) have been prepared and characterized on the basis of elemental analyses, infrared spectra, X-ray photoelectron spectroscopy, molar conductance and thermal analyses.

Liu Guofa; Liu Xiaoxun; Cao Xizhang

1992-01-01

61

Synthesis, characterization and electrochemical studies of ruthenium(III) heterocyclic Schiff bases  

Microsoft Academic Search

A series of hexacoordinated RuIII–PPh3 complexes of general formula [RuCl(PPh3)L] (L = tetradentate Schiff bases derived from the condensation of 2-furaldehyde or thiophene-2-carboxyaldehyde with alkyl and aryl diamines have been synthesized. The complexes were characterized by elemental analyses, spectroscopic and cyclic voltammetric studies. All of the complexes were paramagnetic. Coordination of the Schiff base appears to occur through the two

Gopalakrishnan Karthikeyan; Ponnuchamy Pitchaimani

2003-01-01

62

Synthesis, spectroscopic, DNA cleavage and antibacterial activity of binuclear schiff base complexes  

Microsoft Academic Search

The binuclear Schiff base complexes are formed newly using different transition metals at their stable oxidation state as Cu(II), Ni(II), and VO(II). 3,3?,4,4?-tetraminobiphenyl and 2-aminobenzaldehyde were condensed to form a new Schiff base ligand having an two N4 group responsible for better chelating to the metal centers. The ligand and their complexes have been established by analytical, spectral and electrochemical

N. Mahalakshmi; R. Rajavel

63

Synthesis, spectroscopy, electrochemistry and thermal study of vanadyl unsymmetrical Schiff base complexes  

Microsoft Academic Search

The new tetradentate unsymmetrical N2O2 Schiff base ligands and VO(IV) complexes were synthesised and characterized by using IR, UV–Vis and elemental analysis. The electrochemical properties of the vanadyl complexes were investigated by means of cyclic voltammetry. The oxidation potentials are increased by increasing the electron-withdrawing properties of functional groups of the Schiff base ligands according to the trend of MeO

Ali Hossein Kianfar; Vida Sobhani; Morteza Dostani; Mojtaba Shamsipur; Mahmoud Roushani

2011-01-01

64

Investigation of some Schiff bases as acidic corrosion of alloy AA3102  

Microsoft Academic Search

The inhibiting effect of some Schiff bases on the corrosion of AA3102 aluminium in 0.1M HCl has been studied by means of the hydrogen evolution and electrochemical impedance spectroscopy. The Schiff bases 2-hydroxyacetophenone-etansulphonylhydrazone, Salicylaldehyde-etansulphonylhydrazone, 5-bromosalicylal-dehyde-etansulphonylhydrazone and 5-chlorosalicylaldehyde-etansulphonylhydrazone were synthesized from salicylaldehyde and the corresponding amine. The hydrogen evolution tests showed that the corrosion resistance was greatly enhanced in presence of

A. Aytaç; Ü. Özmen; M. Kabasakalo?lu

2005-01-01

65

Complexes of Rare Earth Nitrate Schiff Base Derived from O-Vanillin and 2Naphthylamine  

Microsoft Academic Search

Complexes of rare earth nitrates with Schiff bases derived from o-vanillin (2-hydroxy-3-methoxy-benzaldehyde) and 2-naphthylamine have been prepared and characterized. The complexes have been given the general formula [LnL2 (NO3)] (NO3)2 (where Ln = La, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu; L = Schiff base) on the basis of elemental analyses, molar conductance, infrared spectra,

Liu Guofa; Na Chongwu; Li Bin

1990-01-01

66

Synthesis, spectral, and catalytic studies of ruthenium(II) unsymmetrical Schiff-base complexes  

Microsoft Academic Search

Unsymmetrically-substituted ruthenium(II) Schiff-base complexes, [Ru(CO)(B)(L)] [B = PPh3, AsPh3 or Py; L = dianion of tetradentate unsymmetrical Schiff-base ligand; x = 4–7, L = salen-o-hyac, L = valen-o-hyac, L = salphen-o-hyac, L = valen-2-hacn], were prepared and characterized by analytical, IR, electronic, and H NMR spectral studies. The new complexes were tested for their catalytic activity towards the oxidation of

S. Gowri; J. Priya; M. Muthukumar; P. Viswanathamurthi

2009-01-01

67

Synthesis and characterization of some heterocyclic schiff bases: potential anticonvulsant agents  

Microsoft Academic Search

A series of novel schiff bases of 3-aminomethyl pyridine have been synthesized through condensation reaction with substituted\\u000a aryl aldehydes\\/ketones and\\/cyclic ketones. These schiff bases were screened for anticonvulsant activity. The chemical structures\\u000a of synthesized compounds were confirmed by FT-IR, 1H-NMR, spectroscopy, and elemental analysis. A number of compounds were observed to exhibit seizures protection after intraperitoneal\\u000a administration at the dose

Shailendra Pandey; R. S. Srivastava

68

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

NASA Astrophysics Data System (ADS)

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.

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

2006-04-01

69

Electrochemical and theoretical investigation on the corrosion of aluminium in acidic solution containing some Schiff bases  

NASA Astrophysics Data System (ADS)

The effect of newly synthesised three Schiff bases—2-[2-aza-2-(5-methyl(2-pyridly))vinyl]phenol, 2-[2-aza-2-(5-methyl(2-pyridly))vinyl]-4-bromophenol, 2-[2-aza-2-(5-methyl(2-pyridly))vinyl]-4-chlorophenol—on the corrosion behaviour of aluminium in 0.1 M HCl were investigated using potentiodynamic polarisation, electrochemical impedance spectroscopy and linear polarisation methods. Polarisation curves indicate that all studied Schiff bases were acting as mixed type inhibitors. All measurements show that inhibition efficiencies increase with increase in inhibitor concentration. This reveals that inhibitive actions of inhibitors were mainly due to adsorption on aluminium surface. Adsorption of these inhibitors follows Langmuir adsorption isotherm. Thermodynamic parameters of adsorption (Kads, ?Gads) of studied Schiff bases were calculated using Langmuir adsorption isotherm. The variation in inhibition efficiency values depends on the type of functional groups substituted on benzene ring. It was found that the presence of bromine and chlorine atoms in the molecular structure of studied Schiff bases facilitate the adsorption of molecule on aluminium surface. The correlation between the inhibition efficiencies of studied Schiff bases and their molecular structure has been investigated using quantum chemical parameters obtained by MNDO semi-empirical SCF-MO methods. These results indicate that adsorption of studied Schiff bases depends on the charge density of adsorption centres and dipole moments.

Yurt, A.; Ulutas, S.; Dal, H.

2006-11-01

70

COORDINATION BEHAVIOR OF BIOLOGICALLY ACTIVE SCHIFF BASES OF AMINO ACIDS TOWARDS SILICON(IV) ION  

Microsoft Academic Search

Reactions of diethoxydimethylsilane with Schiff bases derived from the condensation of fur-furaldehyde. indole-3-carbaldehyde with alanine, glycine, valine, isoleucine and tryptophan in a 1:2 molar ratio give a new series of Me2Si (NO)2 type of organosilicon (IV) complexes. The complexes are monomeric and non-electrolytic in nature. The coordination behaviour of Schiff babes through organosilicon (IV) has been investigated by IR, H,

M. Sharma; B. Khungar; S. Varshney; H. L. Singh; U. D. Tripaathi; A. K. Varshney

2001-01-01

71

Spectrophotometric and spectrofluorimetric investigation of different equilibria of a recently synthesized Schiff base with the aid of chemometric methods  

Microsoft Academic Search

In this study ground and excited states acidic dissociation constants of a recently synthesized Schiff base was obtained in a DMF:water mixture of 30:70 (v\\/v) using absorption and fluorescent spectra of the Schiff base in different pH values with the aid of chemometric methods. In addition, the fluorescent of the two kinds of tautomers of this Schiff base was investigated

Abbas Afkhami; Hasan Keypour; Farzad Khajavi; Majid Rezaeivala

2011-01-01

72

[Theoretical study on geometrical structure and spectrum of 4-(2-nitrobenzylideneamino) phenyl ethanone Schiff base].  

PubMed

The UV absorption spectra, fluorescence emission spectra and fluorescence quantum yield of the title Schiff base were studied by experiment. The results showed that this compound displayed superior fluorescence properties. Geometrical optimization of the title compound was carried out by employing density functional theory (DFT) method at the B3LYP/6-311G(d) level. The calculation results indicated that the title compound has comparatively stronger aromaticity and larger conjugate system. For the optimal configuration, there is no imaginary frequency after vibrational analysis, which indicates that the structure is stable. Based on the optimized structure for the ground state time-dependent density functional theory (TD-DFT) calculations were carried out at the B3LYP/6-311G level to predict the absorption spectra. The single-excitation configuration interaction (CIS) method was used to optimize the structure of the first excited state, and then TD-DFT calculations were carried out to predict the emission spectra. The results indicated that the wavelengths of the absorption and emission spectra are consistent with the experimental data. PMID:23697099

Liang, Xiao-Rui; Jiang, Yan-Lan; Zhang, Jing; Qu, Cheng-Li; Wang, Gang; Wang, Xiu-Juan; Zhao, Bo

2013-02-01

73

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

PubMed

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 degrees C and at 0.1 M KNO3 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. PMID:17913572

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

2007-07-25

74

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

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

75

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

PubMed

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, (1)H NMR and (13)C 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. PMID:19081293

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

2008-10-31

76

Impact of proton transfer phenomena on the electronic structure of model Schiff bases: An AIM?NBO?ELF study.  

PubMed

Understanding of the electronic structure evolution due to a proton dynamics is a key issue in biochemistry and material science. This paper reports on density functional theory calculations of Schiff bases containing short, strong intramolecular hydrogen bonds where the bridged proton is located: (i) at the donor site, (ii) strongly delocalized, and (iii) at the acceptor site. The mobility of the bridged proton and its influence on the molecular structure and properties of the chosen Schiff base derivatives have been investigated on the basis of Atoms in Molecules, Natural Bond Orbitals, and Electron Localization Function theories. It has been observed that the extent of the bridged proton delocalization is strongly modified by the steric and inductive effects present in the studied compounds introduced by various substituents. It has been shown that: (i) potential energy profiles for the proton motion are extremely dependent on the substitution of the aromatic ring, (ii) the topology of the free electron pairs present at the donor?acceptor site, as well as their electron populations, are affected qualitatively by the bridged proton position, (iii) the distortion of the molecular structure due to the bridged proton dynamics includes the atomic charge fluctuations, which are in some cases non-monotonic, and (iv) topology of the ELF recognizes events of proton detachment from the donor and attachment to the acceptor. The quantitative and qualitative results shed light onto molecular consequences of the proton transfer phenomena. PMID:24160518

Panek, Jaros?aw J; Filarowski, Aleksander; Jezierska-Mazzarello, Aneta

2013-10-21

77

Impact of proton transfer phenomena on the electronic structure of model Schiff bases: An AIM/NBO/ELF study  

NASA Astrophysics Data System (ADS)

Understanding of the electronic structure evolution due to a proton dynamics is a key issue in biochemistry and material science. This paper reports on density functional theory calculations of Schiff bases containing short, strong intramolecular hydrogen bonds where the bridged proton is located: (i) at the donor site, (ii) strongly delocalized, and (iii) at the acceptor site. The mobility of the bridged proton and its influence on the molecular structure and properties of the chosen Schiff base derivatives have been investigated on the basis of Atoms in Molecules, Natural Bond Orbitals, and Electron Localization Function theories. It has been observed that the extent of the bridged proton delocalization is strongly modified by the steric and inductive effects present in the studied compounds introduced by various substituents. It has been shown that: (i) potential energy profiles for the proton motion are extremely dependent on the substitution of the aromatic ring, (ii) the topology of the free electron pairs present at the donor/acceptor site, as well as their electron populations, are affected qualitatively by the bridged proton position, (iii) the distortion of the molecular structure due to the bridged proton dynamics includes the atomic charge fluctuations, which are in some cases non-monotonic, and (iv) topology of the ELF recognizes events of proton detachment from the donor and attachment to the acceptor. The quantitative and qualitative results shed light onto molecular consequences of the proton transfer phenomena.

Panek, Jaros?aw J.; Filarowski, Aleksander; Jezierska-Mazzarello, Aneta

2013-10-01

78

New supramolecular hybrids based on A-type Anderson polyoxometalates and Mn–Schiff-base complexes  

Microsoft Academic Search

By combination of metal–Schiff-base complexes and A-type Anderson heteropolymolybdates, two new metal–Schiff-base polyoxometalate hybrid compounds [Mn(salen)(H2O)2]2Na3[IMo6O24]·18H2O (1) and [Mn(salpn)(H2O)2]2Na3[IMo6O24]·10H2O (2) (salen=N,N?-ethylene-bis(salicylideneiminate) and salpn=N,N?-(1,3-propylene)bis(salicylideneiminate)) have been successfully isolated. Compounds 1 and 2 were characterized by the single crystal X-ray diffraction analysis, elemental analysis, IR spectroscopy, TG analyses and XPS spectra. Single-crystal X-ray diffraction analysis revealed that both compounds exhibit 3-D supramolecular

Qiong Wu; Shi-Wei Lin; Yang-Guang Li; En-Bo Wang

79

A new Schiff base fluorescent probe for imaging Cu2+ in living cells.  

PubMed

A novel probe based on ferrocenyl-1,3,4-thiadiazol-containing Schiff base was synthesized by the reaction of 5-ferrocenyl-1,3,4-thiadiazol-2-amine and 4-(diethylamino)salicylaldehyde, and characterized by IR, NMR, HRMS and X-ray analysis. UV-vis spectral and fluorescence property of the probe were investigated. The probe can be used to colorimetric sensitive and selective fluorescent recognition of Cu(2+) in buffer solution. Moreover, the probe can detect Cu(2+) by electrochemical method. Additionally, the Schiff base was successfully used as a selective and sensitive fluorescent probe for monitoring Cu(2+) ions in living cells. PMID:23666347

Ye, Hui; Ge, Fei; Zhou, Yi-Ming; Liu, Jin-Ting; Zhao, Bao-Xiang

2013-04-22

80

A new Schiff base fluorescent probe for imaging Cu2+ in living cells  

NASA Astrophysics Data System (ADS)

A novel probe based on ferrocenyl-1,3,4-thiadiazol-containing Schiff base was synthesized by the reaction of 5-ferrocenyl-1,3,4-thiadiazol-2-amine and 4-(diethylamino)salicylaldehyde, and characterized by IR, NMR, HRMS and X-ray analysis. UV-vis spectral and fluorescence property of the probe were investigated. The probe can be used to colorimetric sensitive and selective fluorescent recognition of Cu2+ in buffer solution. Moreover, the probe can detect Cu2+ by electrochemical method. Additionally, the Schiff base was successfully used as a selective and sensitive fluorescent probe for monitoring Cu2+ ions in living cells.

Ye, Hui; Ge, Fei; Zhou, Yi-Ming; Liu, Jin-Ting; Zhao, Bao-Xiang

2013-08-01

81

Nickel(II) and copper(II) complexes of unsymmetrical tetradentate reduced Schiff base ligands  

Microsoft Academic Search

Two new reduced Schiff base ligands, [HL1=4-{2-[(pyridin-2-ylmethyl)-amino]-ethylimino}-pentan-2-one and HL2=4-[2-(1-pyridin-2-yl-ethylamino)-ethylimino]-pentan-2-one] have been prepared by reduction of the corresponding tetradentate unsymmetrical Schiff bases derived from 1:1: 1 condensation of 1,2-ethanediamine, acetylacetone and pyridine-2-carboxaldehyde\\/2-acetyl pyridine. Four complexes, [Ni(L1)]ClO4 (1), [Cu(L1)]ClO4 (2), [Ni(L2)]ClO4 (3), and [Cu(L2)]ClO4 (4) with these two reduced Schiff base ligands have been synthesized and structurally characterized by X-ray crystallography. The

Apurba Biswas; Michael G. B. Drew; Ashutosh Ghosh

2010-01-01

82

Biological activity studies on metal complexes of novel tridentate Schiff base ligand. Spectroscopic and thermal characterization  

Microsoft Academic Search

Metal complexes of novel Schiff base (HL) ligand, prepared via condensation of 4-aminoantipyrine and 2-aminophenol, are prepared. 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, ESR spectra and thermal analyses (TG, DTG and DTA). From

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

2009-01-01

83

Synthesis, spectroscopy, electrochemistry and thermal study of vanadyl tridentate Schiff base complexes.  

PubMed

The VO(IV) complexes of tridentate ONO Schiff ligands were synthesised and characterized by IR, UV-vis and elemental analysis. 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: MeOSchiff base ligands and proceeds via first order kinetics. PMID:21803644

Kianfar, Ali Hossein; Paliz, Marzeh; Roushani, Mahmoud; Shamsipur, Mojtaba

2011-07-12

84

Novel neutral phosphinite bridged dinuclear ruthenium(II) arene complexes and their catalytic use in transfer hydrogenation of aromatic ketones: X-ray structure of a new Schiff base, N3,N3?-di-2-hydroxybenzylidene-[2,2?]bipyridinyl-3,3?-diamine  

Microsoft Academic Search

A novel Schiff base N3,N3?-di-2-hydroxybenzylidene-[2,2?]bipyridinyl-3,3?-diamine, 1 was synthesized from condensation of salicylaldehyde with 3,3?-diamino-2,2?-bipyridine. Reaction of 1 with two equivalents of PPh2Cl in the presence of Et3N proceeds in toluene to give N3,N3?-di-2-(diphenylphosphino)benzylidene-[2,2?]bipyridinyl-3,3?-diamine, 2 in quantitative yield. Ruthenium(II) dimers [Ru(?6-arene)(?-Cl)Cl]2 readily react with phosphinite ligand [(Ph2PO)2-C24H16N4], 2 in toluene at room temperature, to afford the neutral derivatives [C24H16N4{OPPh2–Ru(?6-arene)Cl2}2] {arene: benzene

Murat Aydemir; Feyyaz Durap; Ak?n Baysal; Nermin Meric; Ay?egül Bulda?; Bahattin Gümgüm; Saim Özkar; Leyla Tatar Y?ld?r?m

2010-01-01

85

Synthesis, spectra, dioxygen affinity and antifungal activity of Ru(III) Schiff base complexes  

Microsoft Academic Search

The reaction of ruthenium(III) complexes, [RuX3(EPh3)3] (E=As, X=Cl or Br; E=P, X=Cl) and [RuBr3(PPh3)2(CH3OH)] with bidendate Schiff base ligands derived by condensing salicylaldehyde with methylamine (Hsalmet), cyclohexylamine (Hsalchx), 2-aminopyridine (Hsalampy) have been carried out. The complexes were characterized by analytical and spectral studies (IR, electronic and EPR) and are formulated as [RuX(EPh3)(LL?)2] (where LL?=monobasic bidentate Schiff base ligand; E=P or

R Ramesh; S Maheswaran

2003-01-01

86

Ruthenium(II) carbonyl complexes with tridentate Schiff bases and their antibacterial activity  

Microsoft Academic Search

The products obtained by reacting ruthenium (II) complexes [RuHCl(CO)(PPh3)2(B)] [B = PPh3, pyridine (py) or piperidine (pip)] with tridentate Schiff base ligands derived by condensing salicylaldehyde or o-vanillin with o-aminophenol and o-aminothiophenol, have been characterised by analytical, i.r., electronic, 1H-n.m.r. and 31P-n.m.r. spectral studies and formulated as [Ru(L)(CO)(PPh3)(B)] (L = bifunctional tridentate Schiff base anion, B = PPh3, py or

Chinnasamy Jayabalakrishnan; Karuppannan Natarajan

2002-01-01

87

SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL ACTIVITIES OF RUTHENIUM(II) CARBONYL COMPLEXES CONTAINING BIFUNCTIONAL TRIDENTATE SCHIFF BASES  

Microsoft Academic Search

Ruthenium(II) carbonyl complexes have been synthesised by reacting [RuH2(CO)(PPh3)3] or [RuHCl(CO)(PPh3)2(Z)] (Z = PPh3, pyridine (py) or piperidine (pip)) with tridentate Schiff base ligands derived by condensing salicylaldehyde, o-vanillin or o-hydroxyacetophenone with N(4)-phenylsemicarbazide. These complexes have been characterised by analytical, IR, electronic, H NMR and P NMR spectral studies. The complexes of the general formula [Ru(L)(CO)(PPh3)(Z)] (L = Schiff base

C. Jayabalakrishnan; K. Natarajan

2001-01-01

88

Synthesis, characterization and biocidal studies of ruthenium(II) carbonyl complexes containing tetradentate Schiff bases  

Microsoft Academic Search

Stable ruthenium(II) complexes of Schiff bases have been prepared by reacting [RuHCl(CO)(PPh3)2(B)] (B = PPh3, pyridine or piperidine) with bis(o-vanillin)ethylenediimine (valen), bis(o-vanillin)propylene-diimine (valpn), bis(o-vanillin)tetramethylenediimine (valtn), bis(o-vanillin)o-phenylenediimine (valphn), bis(salicylaldehyde)tetramethylenediimine (saltn) and bis(salicylaldehyde)o-phenylenediimine (salphn). These complexes have been characterised by elemental analyses, i.r., electronic, 1H- and 31P{1H}-n.m.r. spectral studies. In all the above reactions, the Schiff bases replace two molecules of Ph3P,

Periasamy Viswanathamurthi; Karuppannan Natarajan

1999-01-01

89

Catalytic and antimicrobial activities of new ruthenium(II) unsymmetrical Schiff base complexes  

Microsoft Academic Search

Hexa-coordinated ruthenium(II) complexes of the type [Ru(CO)(PPh3)(Z)(L)] [Z = PPh3, pyridine (py) or piperidine (pip); L = anion of the Schiff base] have been prepared by reacting [RuHCl(CO)(PPh3)2(Z)] with tridentate Schiff bases derived by condensing anthranilic acid with acetylacetone, salicylaldehyde, o-vanillin and o-hydroxyacetophenone. The complexes were characterised by analytical and spectral (i.r., electronic, 1H- and 31P-n.m.r.) data, and were found

Chinnasamy Jayabalakrishnan; Ramasamy Karvembu; Karuppannan Natarajan

2002-01-01

90

An investigation of chloride-substituted Schiff bases as corrosion inhibitors for steel  

Microsoft Academic Search

Polarization and impedance measurements were performed on steel in deaerated 5% HCl solution with and without Schiff base additives within the concentration range 1×10?4–5×10?3 mol\\/dm3. The Schiff base compounds used were salicylaldimine, R, N-(2-chlorophenyl)salicyaldimine, 2Cl-R, N-(3-chlorophenyl)salicyaldimine, 3Cl-R, and N-(4-chlorophenyl)salicyaldimine, 4Cl-R. It was found that when the concentration of the inhibitors were increased the inhibitor efficiencies, ?, also increased with increasing

Kaan C. Emregül; Raif Kurtaran; Orhan Atakol

2003-01-01

91

Evaluating two new synthesized SN Schiff bases on the corrosion of copper in 15% hydrochloric acid  

Microsoft Academic Search

The inhibiting action of two new Schiff bases namely SB1: 2-({-1-methyl-3-[(2-sulfanylphenyl)imino]butylidene}amino)-1-benzenethiol and SB2: 2-({-1,2-diphenyl-2-[(2-sulfanylphenyl)imino]ethylidene}amino)-1-benzenethiol on the corrosion of copper in hydrochloric acid has been studied. The Schiff bases were synthesized and studied as inhibitors for corrosion of copper. Results of electrochemical impedance and Tafel polarization measurements consistently identify both compounds as good inhibitors. Impedance spectroscopy revealed that the corrosion of

Masoud Salavati-Niasari; S. M. Ghoreishi; B. Ebrahimi

2008-01-01

92

Synthesis, X-ray crystallography, thermal studies, spectroscopic and electrochemistry investigations of uranyl Schiff base complexes.  

PubMed

Some tetradentate salen type Schiff bases and their uranyl complexes were synthesized and characterized by UV-Vis, NMR, IR, TG, C.H.N. and X-ray crystallographic studies. From these investigations it is confirmed that a solvent molecule occupied the fifth position of the equatorial plane of the distorted pentagonal bipyramidal structure. Also, the kinetics of complex decomposition by using thermo gravimetric methods (TG) was studied. The thermal decomposition reactions are first order for the studied complexes. To examine the properties of uranyl complexes according to the substitutional groups, we have carried out the electrochemical studies. The electrochemical reactions of uranyl Schiff base complexes in acetonitrile were reversible. PMID:23321220

Asadi, Zahra; Shorkaei, Mohammad Ranjkesh

2012-12-28

93

A comparative study of electrochemical reduction of isatin and its synthesized Schiff bases at HMDE  

Microsoft Academic Search

The electrochemical behaviour of a series of Schiff base i.e. 3-[5-phenylpyrazol-3-ylimino]indol-2-ones (IIa-e) synthesized\\u000a by the reaction of various 5-substituted isatins with 3-amino-5-phenyl-pyrazole has been investigated and compared with corresponding\\u000a isatin in dimethylformamide in 0·1 M LiCl using cyclic voltammetry at Hanging Mercury Drop Electrode. All synthesized Schiff\\u000a bases exhibit a single irreversible two-electron reduction wave in contrast with the two

Alpana K. Gupta; Rajendra S. Sindal

2009-01-01

94

Electrochemical and theoretical investigation on the corrosion of aluminium in acidic solution containing some Schiff bases  

Microsoft Academic Search

The effect of newly synthesised three Schiff bases—2-[2-aza-2-(5-methyl(2-pyridly))vinyl]phenol, 2-[2-aza-2-(5-methyl(2-pyridly))vinyl]-4-bromophenol, 2-[2-aza-2-(5-methyl(2-pyridly))vinyl]-4-chlorophenol—on the corrosion behaviour of aluminium in 0.1M HCl were investigated using potentiodynamic polarisation, electrochemical impedance spectroscopy and linear polarisation methods. Polarisation curves indicate that all studied Schiff bases were acting as mixed type inhibitors. All measurements show that inhibition efficiencies increase with increase in inhibitor concentration. This reveals that inhibitive

A. Yurt; S. Ulutas; H. Dal

2006-01-01

95

Electrocatalytic sensor devices: (I) cyclopentadienylnickel(II) thiolato Schiff base monolayer self-assembled on gold  

Microsoft Academic Search

The fabrication of a self-assembled monolayer (SAM) of a cyclopentadienylnickel(II) thiolato Schiff base compound, [Ni(SC6H4NC(H)C6H4OCH2CH2SMe)(?5-C5H5)]2 on a gold electrode is described. Effective electronic communication between the Ni(II) centres and the gold surface was established by electrochemically cycling the Schiff base-doped Au electrode in 0.1M NaOH from ?200mV to +600mV. The SAM-modified electrode exhibited quasi-reversible electrochemistry. The integrity of this electrocatalytic

Aoife Morrin; Richard M. Moutloali; Anthony J. Killard; Malcolm R. Smyth; James Darkwa; Emmanuel I. Iwuoha

2004-01-01

96

Novel bidentate ruthenium(III) Schiff base complexes: synthetic, spectral, electrochemical, catalytic and antimicrobial studies  

Microsoft Academic Search

RuIII complexes of the type [RuX(L)2(E)] (X = Cl or Br; L = novel bidentate Schiff base ligand; E = PPh3 or AsPh3) have been prepared by reacting [RuX3(E)3] or [RuBr3(PPh3)2(MeOH)] with two novel bidentate Schiff base ligands derived from 4-(1-methyl-1-mesitylcyclobutane-3-yl)-2-aminothiazole, in a 1:2 molar ratio in benzene, and characterised by analytical, spectral (i.r., electronic, 1H-, 13C- n.m.r., and e.p.r.)

T. Daniel Thangadurai; Son-Ki Ihm

2004-01-01

97

Protection of copper corrosion by modification of self-assembled films of Schiff bases with alkanethiol  

Microsoft Academic Search

The corrosion protection of self-assembled films derived from Schiff bases, including N-2-hydroxyphenyl-(3-methoxy-salicylidenimine) (V-bso), N-2-hydroxyphenyl-(salicylidenimine) (S-bso) and N,N?-o-phenylen-bis(salicylidenimine) (S-o-ph-S), on copper surfaces have been probed by electrochemical techniques in an aqueous electrolyte. These studies suggest that the pure films of Schiff bases possess some unfilled defect sites. However, when the films were modified by 1-dodecanethiol (C12H25SH, abbreviated as DT), the quality

Zhenlan Quan; Shenhao Chen; Shulan Li

2001-01-01

98

Manganese(III) Schiff-base complexes involving heterocyclic ?-diketone and diethylene triamine  

Microsoft Academic Search

Synthesis, spectral, thermal and coordination aspects of pentadentate Schiff-base complexes of the type [Mn(L)(X)] · H2O [where H2L = N,N?–diethylamine bis(1-phenyl-3-methyl-4-acetylimino-2-pyrazoline-5-ol) and X=NCS, NO3, ClO4, CN or N3] are reported. The Schiff-base ligand (H2L) and metal complexes have been characterized by elemental analysis, FT-IR, H-NMR, magnetic measurements, molar conductivity measurements, electronic spectra, cyclic voltammetric and thermal studies. Magnetic moment values

C. K. Modi; I. A. Patel; B. T. Thaker

2008-01-01

99

ESR Characterization of Two Oxovanadium (IV) Schiff Base Complexes Derived from Tris(2-aminoethyl)amine  

Microsoft Academic Search

The compounds, C21H27N4O3(L) and C21H27N7(L), is a tripodal Schiff base that was obtained from the reaction of tris(2-aminoethyl)amine (tren) and furan-2-carbaldehyde and pyrole- 2- carbaldehyde. The tripodal Schiff bases and their oxovanadium complexes have been characterized on the basis of the results of the elemental analysis, magnetic susceptibility measurements and spectroscopic studies FT-IR, H-NMR, UV–Vis, ESR, magnetic moment and thermal

Mustafa Sahin; Nuriye Kocak; Ulku Sayin; Mustafa Yilmaz

2012-01-01

100

Spectroscopic studies of amino acid ionic liquid-supported Schiff bases.  

PubMed

Amino acid ionic liquid-supported Schiff bases, derivatives of salicylaldehyde and various amino acids (L-threonine, L-valine, L-leucine, L-isoleucine and L-histidine) have been investigated by means of various spectroscopic techniques (NMR, UV-Vis, IR, MS) and deuterium isotope effects on ¹³C-NMR chemical shifts. The results have shown that in all studied amino acid ionic liquid-supported Schiff bases (except the L-histidine derivative) a proton transfer equilibrium exists and the presence of the COO? group stabilizes the proton transferred NH-form. PMID:23629755

Ossowicz, Paula; Janus, Ewa; Schroeder, Grzegorz; Rozwadowski, Zbigniew

2013-04-29

101

1H NMR, 13C NMR and mass spectral studies of some Schiff bases derived from 3-amino-1,2,4-triazole  

NASA Astrophysics Data System (ADS)

Heterocyclic Schiff bases derived from 3-amino-1,2,4-triazole and different substituted aromatic aldehydes are prepared and subjected to 1H NMR, 13C NMR and mass spectral analyses. 1H NMR spectra in DMSO exhibit a sharp singlet within the 9.35-8.90 ppm region which corresponds to the azomethine proton. The position of this signal is largely dependent on the nature of the substituents on the benzal moiety. It is observed that the shape, position and the integration value of the signal of the aromatic proton of the triazole ring ( 5C) are clearly affected by the rate of exchange, relaxation time, concentration of solution as well as the solvent used. 13C NMR is taken as substantial support for the results reached from 1H NMR studies. The mass spectral results are taken as a tool to confirm the structure of the investigated compounds. The base peak (100%), mostly the M-1 peak, indicates the facile loss of hydrogen radical. The fragmentation pattern of the unsubstituted Schiff base is taken as the general scheme. Differences in the other schemes result from the effect of the electronegativity of the substituents attached to the aromatic ring.

Issa, Y. M.; Hassib, H. B.; Abdelaal, H. E.

2009-11-01

102

Synthesis of ?-Aminophosphonic Acids Sy Pd(0)Alkylation of Diethyl Aminomethylphosphonate Schiff Bases  

Microsoft Academic Search

Aminoalkyl phosphonic compounds have many interesting biological properties: they are used as herbicides, antibiotics and enzyme inhibitors. Several approaches to the preparation of ?-aminophosphonic acids have been reported. One efficient method using the schiff base of diethyl amino methylphosphonate 1 has been developped, allowing alkylation at the ? carbon after deprotonation using strong bases such as LDA. In our continuing

J. P. Genet; J. Uziel; S. Juge

1990-01-01

103

A sandwich-type triple-decker lanthanide complex with mixed phthalocyanine and Schiff base ligands.  

PubMed

A new triple-decker dinuclear sandwich-type dysprosium complex based on both the phthalocyanine ligand and the tetradentate Schiff base ligand was synthesized, which is of interest for synthetic chemistry and also shows single-molecule magnetic behaviour. PMID:23818021

Gao, Feng; Li, Yu-Yang; Liu, Cai-Ming; Li, Yi-Zhi; Zuo, Jing-Lin

2013-08-21

104

Interactions of some Schiff base compounds with mild steel surface in hydrochloric acid solution  

Microsoft Academic Search

The inhibition effect of the Schiff bases N,N?-bis(salicylidene)-1,2-ethylenediamine (Salen), N,N?-bis(5-methoxysalicylidene)-1,2-ethylenediamine (MeO-Salen) and N,N?-bis(5-nitrosalicylidene)-1,2-ethylenediamine (NO2-Salen) on the corrosion of the mild steel in 1.0M HCl has been studied by electrochemical impedance spectroscopy (EIS), linear polarisation resistance (LPR) and Tafel polarisation measurements. Maximum inhibition for MeO-Salen was obtained. Results showed that the inhibition efficiency have increased when the concentration of the Schiff

Emel Bayol; Tijen Gürten; A. Ali Gürten; Mehmet Erbil

2008-01-01

105

Nad(P)H vs. Schiff base fluorescence by spectroscopy, imaging, and maximum sensitivity micrographs at the convergence of cellular detoxification, senescence, and transformation  

Microsoft Academic Search

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

Elli Kohen; Joseph G. Hirschberg; Cahide Kohen; Marco Monti

1999-01-01

106

Spin crossover in iron(III) Schiff-base 1-D chain complexes.  

PubMed

A series of iron(III) 1-D polymeric materials of the general formula [Fe(III)(Schiff-base)(L)](BPh(4)).n(CH(3)OH) (Schiff base = N,N'-ethylenebis(salicylaldimine) (H(2)salen), N,N'-o-phenylenebis(salicylaldimine) (H(2)salophen) and N,N'-ethylenebis(acety1acetone)-2,2'-imine (H(2) acen); L = bridging di-pyridyl or di-imidazole ligand, n = 0-4) and analogues therein, have been synthesised and structurally and magnetically characterised. In this series, a range of structural motifs are observed including linear 1-D chains, hydrogen-bonded chains, a 'hybrid' 1-D chain- and -dimer compound and a hydrogen-bonded dinuclear material; all exhibit extensive intermolecular interactions. The magnetic consequences of varying both the equatorial Schiff-base ligands and axial bridging ligands have been investigated. Overall, we find that, independent of the axial bridging ligand employed, the salen equatorial ligand results in a high spin character and the acen ligand results in spin crossover character, generally with a spin transition of a gradual nature. Variations in magnetic behaviour can be rationalized, in part, in terms of the C(2)N(2) backbone conformation of the equatorial Schiff base ligand, which may either inhibit or allow a spin transition. PMID:20023945

Ross, Tamsyn M; Neville, Suzanne M; Innes, David S; Turner, David R; Moubaraki, Boujemaa; Murray, Keith S

2009-10-08

107

Ferrocenyl Schiff base as novel antioxidant to protect DNA against the oxidation damage.  

PubMed

The antioxidant capacities of ferrocenyl Schiff bases including o-(1-ferrocenylethylideneamino)phenol (OFP), m-(1-ferrocenylethylideneamino)phenol (MFP), and p-(1-ferrocenylethylideneamino)phenol (PFP) were evaluated in 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), Cu(2+)/glutathione (GSH), and hydroxyl radical (()OH)-induced oxidation of DNA, and in trapping 2,2'-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS+(.)), respectively. OFP, MFP and PFP possessed similar activities to trap DPPH and ABTS+(.). All the ferrocenyl Schiff bases employed herein behaved as prooxidants in Cu(2+)/GSH- and (.)OH-induced oxidation of DNA except that OFP exhibited weak antioxidant activity in ()OH-induced oxidation of DNA. PFP, OFP and MFP can terminate about 15.2, 11.3, and 9.4 radical-chain-propagations in AAPH-induced oxidation of DNA. Especially, the introduction of ferrocenyl group to Schiff base increased the antioxidant effectiveness more remarkably than benzene-related Schiff bases. PMID:21782019

Li, Yan-Feng; Liu, Zai-Qun

2011-07-12

108

Schiff bases as corrosion inhibitors for aluminium in hydrochloric acid solution  

Microsoft Academic Search

The inhibition of the corrosion of Al in hydrochloric acid solution by some Schiff bases has been studied in relation to the concentration of the inhibitor as well as the temperature. The inhibition efficiency increases with increasing inhibitor concentration. The inhibitors appear to function through the Langmuir isotherm. Polarisation studies indicate that the compounds used are cathodic inhibitors. The corrosion

Gamal K. Gomma; Mostafa H. Wahdan

1995-01-01

109

Synthesis and electrochemical polymerization of some monomers with Schiff base or vinylene structures and thiophene moieties  

Microsoft Academic Search

The synthesis of five monomers with thiophene moieties and conjugated Schiff base or phenylene-vinylene bridges between them was performed. The electrochemical characterization and MO calculations evidenced the possibility of coupling at the 2,2? positions of the heterocycles. The electrochemical oxidative polymerization of the monomers was carried out in galvanostatic conditions. The resulting polymers were characterised by usual spectral methods and

C. I Simionescu; I Cianga; M Ivanoiu; Al Duca; I Cocarla; M Grigoras

1999-01-01

110

Electrochemical and spectroelectrochemical properties of copper(II) Schiff-base complexes  

Microsoft Academic Search

The electrochemical behaviour of several copper(II) complexes with Schiff-base ligands containing pyrrole groups has been investigated in aprotic solvents by cyclic voltammetry and spectroelectrochemistry. Electrochemical oxidation of copper(II) complexes in acetonitrile produces conducting polymeric films at the electrode surface. The modified electrodes were electrochemically and spectrochemically characterized and their electrocatalytical properties have been examined.

J Losada; I del Peso; L Beyer

2001-01-01

111

Vibration spectra of complexes of rare earth nitrate with some Schiff bases  

NASA Astrophysics Data System (ADS)

Infrared and Raman spectra of complexes of rare earth nitrate with Schiff bases derived from vanillin (3-methoxy-4-hydroxy-benzaldehyde) or o-vanillin (2-hydroxy-3-methoxy-benzaldehyde) and p-toluidine, 1-naphthylamine, 2-naphthylamine are reported.

Guofa, Liu

1994-06-01

112

CYTOTOXICITY OF ENANTIOMERS OF GOSSYPOL SCHIFF'S BASES AND OPTICAL STABILITY OF GOSSYPOLONE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Optical Schiff's bases of gossypol were prepared with chiral gossypol and ethylamine. As has been similarly observed among the gossypol enantiomers, the (-)-gossypol ethylimine was more active than either the (+)-gossypol ethylimine or the racemic gossypol ethylimine against KB and MCF7 cells. Gos...

113

A Cautionary Note Regarding the Reductive Dimerization of Schiff Bases by Zinc Dust  

Microsoft Academic Search

Having some interest in the reductive dimerization of Schiff bases, 1, to substituted 1,2-bisanilinoethanes, 2, the recent report describing the use of zinc dust to effect this reaction caught our attention. In particular, the dimeric products were reported to have sharp melting points implying that in each case only one of the two possible diastereomeric dimers was formed.

James G. Smith; Thomas J. Boettger

1981-01-01

114

Electric-Field-Induced Schiff-Base Deprotonation in D85N Mutant Bacteriorhodopsin  

Microsoft Academic Search

The application of an external electric field to dry films of Asp-85 --> Asn mutant bacteriorhodopsin causes deprotonation of the Schiff base, resulting in a shift of the optical absorption maximum from 600 nm to 400 nm. This is in marked contrast to the case of wild-type bacteriorhodopsin films, in which electric fields produce a red-shifted product whose optical properties

Paul Kolodner; Evgeniy P. Lukashev; Yuan-Chin Ching; Denis L. Rousseau

1996-01-01

115

Development and Evaluation of Cefadroxil Drug Loaded Biopolymeric Films Based on Chitosan-Furfural Schiff Base  

PubMed Central

Cefadroxil drug loaded biopolymeric films of chitosan-furfural schiff base were prepared by reacting chitosan with furfural in presence of acetic acid and perchloric acid respectively for the external use. Prepared films were evaluated for their strength, swelling index, thickness, drug content, uniformity, tensile strength, percent elongation, FTIR spectral analysis and SEM. The results of in vitro diffusion studies revealed that the films exhibited enhanced drug diffusion as compared to the films prepared using untreated chitosan. The films also demonstrated good to moderate antibacterial activities against selective gram positive and gram negative bacteria.

Dixit, Ritu B.; Uplana, Rahul A.; Patel, Vishnu A.; Dixit, Bharat C.; Patel, Tarosh S.

2010-01-01

116

Binuclear Ruthenium(II) Carbonyl Schiff Base Complexes Containing N2O2 Donors and their Catalytic and Biological Activities  

Microsoft Academic Search

An interesting series of binuclear ruthenium(II) Schiff base complexes of the type [RuCl(CO)(EPh3)2(B)]2L (where EP\\/As; BPPh3\\/AsPh3\\/Py; Lbinucleating monobasic bidendate Schiff base ligand) have been synthesized by reacting [RuCl(CO)(EPh3)2(B)]2 with Schiff bases derived from acetoacetanilide and salicylaldehyde\\/o-hydroxyacetophenone\\/o-vanillin\\/2-hydroxy-1-naphthaldehyde with benzene. The complexes were characterized by analytical, spectroscopic, and electrochemical measurements. The new diamagnetic ruthenium(II) complexes have N2O2 metal binding sites, which are

Nagarajan Sathya; Gunasekaran Raja; Chinnasamy Jayabalakrishnan

2011-01-01

117

Synthesis, Spectral, Catalytic, and Bioactivity Studies of Ruthenium(III) Complexes Containing ONO Donor Schiff Base Ligands  

Microsoft Academic Search

New hexa-coordinated ruthenium(III) complexes of the type [RuX(EPh3)2L] (X Cl or Br; E P or As; L deprotonated dibasic tridentate Schiff base ligand) have been synthesized by the reactions of [RuCl3(PPh3)3], [RuCl3(AsPh3)3] or [RuBr3(AsPh3)3] with the appropriate Schiff bases. The Schiff bases were synthesized by the condensation of anthranilic acid with acetyl acetone\\/salicylaldehyde\\/o-vanillin\\/o-hydroxy acetophenone. The complexes were characterized by elemental

N. Thilagavathi; C. Jayabalakrishnan

2011-01-01

118

Effect of Schiff Bases Containing Pyridyl Group as Corrosion Inhibitors for Low Carbon Steel in 0.1 M HCl  

Microsoft Academic Search

The inhibiting effect of four newly synthesised Schiff bases containing pyridyl group was investigated on the corrosion of low carbon steel in 0.1 M hydrochloric acid solution under various conditions by potentiodynamic polarisation method and impedance measurements. The Schiff bases used were 2-((1Z)-1-aza-2-(2-pyridyl)vinyl)benzene-1-thiol, (1Z)-1-aza-1,2- di(2-pyridyl)ethene, [((1Z)-1-aza-2-(2-pyridyl)vinyl)amino]benzene-1-thione and 2-((1Z)-1-aza-2-(2-pyridyl)vinyl)benzothiazole. All the Schiff bases inhibit corrosion of low carbon steel and their inhibition

A. Yurt; G. Bereket; A. Kivrak; A. Balaban; B. Erk

2005-01-01

119

Synthesis, Characterization, and Photochemical Studies of Some Copper Complexes of Schiff Bases Derived from 3?Hydrazino?6?methyl[1,2,4]triazin?5(4H)one  

Microsoft Academic Search

Cu(II) complexes of new bidentate and tridentate Schiff bases derived from the condensation of 3?hydrazino?6?methyl[1,2,4]triazin?5(4H)one and aromatic aldehyde derivatives were synthesized and characterized. The structure of the complexes proposed according to elemental analyses, molar conductance, IR UV?Visible absorption spectra is square?planar. The thermodecomposition kinetics of the complexes were investigated under non?isothermal condition. TG and DTG curves indicated that the complexes

Ahmed H. Osman; Magda S. Saleh; Sanaa M. Mahmoud

2004-01-01

120

Synthesis, Characterization and Electrochemical Behaviour of Some Manganese and Copper Complexes with Tetradentate Schiff Base Ligands  

Microsoft Academic Search

A series of symmetrical tetradentate Schiff bases derived from substituted salicylaldehyde and ethylenediamine were prepared and characterized by elemental analysis, IR, UV-Visible and H NMR spectroscopy. The interaction of these bases with MnCl2 4H2O and CuCI2 2H2O have been studied, leading to the preparation of manganese(II) and copper(II) complexes. Microanalysis, molar conductance, IR, UV-Visible spectroscopy, magnetic measurements and ESR spectra

N. Tidjani-Rahmouni; S. Djebbar-Sid; N. Chenah; O. Benali-Baitich

1999-01-01

121

Electrochemical reduction of Schiff base ligands H 2salen and H 2salophen  

Microsoft Academic Search

The electrochemical reduction of the Schiff base ligands N,N?-1,2-ethylenebis(salicylideneimine) and N,N?-1,2-phenylenebis(salicylideneimine) has been investigated in DMF by cyclic voltammetry, coulometry and controlled potential electrolysis. The process involves a self-protonation mechanism whereby the two-electron reduction product, a cyclic derivative, is formed together with the conjugate base of the substrate, as a consequence of proton transfer from the substrate itself to the

Abdirisak Ahmed Isse; Armando Gennaro; Elio Vianello

1997-01-01

122

Multinuclear alkylaluminium macrocyclic Schiff base complexes: influence of procatalyst structure on the ring opening polymerisation of epsilon-caprolactone.  

PubMed

Two remote dialkylaluminium centres supported by a macrocyclic Schiff base ligand exhibited beneficial cooperative effects, whilst aluminoxane-type bonding proved to be detrimental to activity for the ring opening polymerisation of epsilon-caprolactone. PMID:18830470

Arbaoui, Abdessamad; Redshaw, Carl; Hughes, David L

2008-09-05

123

Transition Metal Complexes of Some Schiff Bases Derived from 2Amino4Phenyl5-Arylazothiazoles and Salicylaldehyde  

Microsoft Academic Search

Four new Schiff bases were synthesized by the condensation of salicylaldehyde and 2-amino-4-phenyl-5-arylazothiazoles. Metal complexes of the type M(SchB)2 and M?(Sch.B)3 where M = Pd(II) M? = Rh(III), Ru(III), Fe(II1) and SchB = different newly synthesized monobasic Schiff bases were prepared and characterized on the basis of chemical analysis, conductance measurements, magnetic moments, infrared and electronic spectral studies. Mössbauer spectral

C. L. Shaxma; V. Mishra; S. S. Narvi

1986-01-01

124

Rearrangement of manganese(III) complexes with asymmetrical N3O and N2O2 Schiff bases  

Microsoft Academic Search

MnIII complexes of asymmetric tetradentate Schiff bases, derived from HAE (7-amino-4-methyl-5-aza-3-hepten-2-one) and aldehydes or ketones containing imidazole, pyrazine or dehydroacetic fragments, have been prepared and thoroughly characterised by elemental analysis, i.r. and electronic spectroscopy, mass spectrometry and by magnetic measurements. The X-ray crystal structure of [Mn(dha)2(H2O)2] (Hdha = dehydroacetic acid), obtained by rearrangement of the corresponding asymmetrical Schiff base complex,

M. I. Fernández; M. Fondo; A. M. García-Deibe; B. Fernández; M. J. Rodríguez; M. R. Bermejo

2002-01-01

125

Spectral, Magnetic, Thermal and DNA Interaction of Ni(II) Complexes of Glutamic Acid Schiff-Bases  

Microsoft Academic Search

Ni(II) complexes with Schiff-bases obtained by condensation of glutamic acid with salicylaldehyde; 2,3-; 2,4-; 2,5-dihydroxybenzaldehyde and o-hydroxynaphthaldehyde have been synthesized using the template method in ethanol or ammonia media. They were characterized by elemental analyses, conductivity measurements, magnetic moment, UV, IR and H NMR spectra as well as thermal analysis (TG, DTG, DTA). The Schiff-bases are dibasic tridentate or tetradentate

A. S. Orabi; A. M. Abbas; S. A. Sallam

2012-01-01

126

Ruthenium(III) Schiff Base Complexes: Catalytic Activity in Aryl–Aryl Coupling Reaction and Antimicrobial Activity  

Microsoft Academic Search

The synthesis and characterization of several hexa?coordinated ruthenium(III) Schiff base complexes of the type [RuX(EPh3)2(L)] (E=P or As; X=Cl or Br; L = anion of the Schiff bases derived by the condensation of salicylaldehyde or o?hydroxyacetophenone with benzoylhydrazine or p?chlorobenzoylhydrazine) are reported. IR, EPR, electronic spectra and cyclic voltammetric data of the complexes are discussed. An octahedral geometry has been tentatively proposed

C. Jayabalakrishnan; R. Karvembu; K. Natarajan

2003-01-01

127

Thorium[IV], Uranium[VI] and Ce[III] complexes with bidentate and tridentate Schiff bases  

Microsoft Academic Search

Thorium(IV), Uranium(VI) and Cerium(III) complexes with some bidentate and tridentateSchiff bases-derived from salicyladehyde-have been prepared. The effect of the molecular structure of theSchiff base molecule on its tendency towards complex formation has been studied. The structures of the complexes have been investigated by elemental analysis, molar ratio and continuous variation spectrophotometric methods, infrared spectra and conductometric titrations; the apparent formation

Mohamed R. Mahmoud; Issa M. Issa; Mahmoud S. El-Melliegy; S. A. El-Gyar

1978-01-01

128

The catalytic performance and corrosion inhibition of CuCl\\/Schiff base system in homogeneous oxidative carbonylation of methanol  

Microsoft Academic Search

A homogeneous catalytic system, CuCl\\/Schiff base, was studied in the synthesis of dimethyl carbonate (DMC) by oxidative carbonylation of methanol. It was found that among a number of Schiff bases studied, 1,10-phenanthroline (phen) was the most effective promoter in terms of both the catalytic activity and the corrosion inhibition. The catalytic performance of CuCl was enhanced dramatically and the corrosion

Wanling Mo; Hui Xiong; Tao Li; Xiaochuan Guo; Guangxing Li

2006-01-01

129

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

PubMed Central

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.

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

2008-01-01

130

Synthesis, characterization, tautomerism and theoretical study of some new Schiff base derivatives  

NASA Astrophysics Data System (ADS)

New Schiff base derivatives were prepared by the condensation of 5-chloro and 5-bromo salicylaldehyde with bis( o-aminophenol)ethers. Five bis( o-nitrophenol)ether compounds were synthesized using some ditosylate, 1,3-dibromopropane and 1,4-dibromobuthane with o-nitrophenol. These compounds were reduced to bis( o-aminophenol)ethers. The products have been characterized by elemental analysis, FTIR, 1H, 13C NMR, HETCOR and HMBC spectroscopic techniques. The tautomerisms of all of the Schiff bases compounds were determined in DMSO, CHCl 3, C 2H 5OH and C 6H 12 solvents and in both acidic and basic media using the UV-vis spectrophotometric method. The heat of formation (? Hf), enthalpy (? H), entropy (? S), Gibbs free energy (? Gf and ? G), stable isomers, conformations and tautomers of the synthesized compounds are calculated using the MOPAC2009 (PM6) program.

Türko?lu, Gül?en; Berber, Halil; Dal, Hakan; Ö?retir, Cemil

2011-09-01

131

Schiff base complexes of ruthenium(II) and their use as catalytic oxidants  

Microsoft Academic Search

Some ruthenium(II) Schiff base complexes Ru(PPh3)2(L4) (1b, 2b, 3b) (L4=tetradentate ligand), Ru(PPh3)2(H2O)(L3) (4b) (L3=tridentate ligand), Ru(PPh3)2(L2)2 (5b, 6b) (L2=bidentate ligand) and RuCl2(PPh3)2L2 (7b) (L= monodentate ligand) are reported. The Schiff bases used have been derived from condensation of salicylaldehyde with 1,2-diaminobenzene (1a), 3,4-diaminotoluene (2a), 1,2-diaminocyclohexane (3a), 2-aminophenol (4a), p-toluidine (5a), 4-aminobenzoic acid (6a) and by condensation of 4-chlorobenzaldehyde with 4-aminobenzoic

Minu G Bhowon; H. Li Kam Wah; R Narain

1998-01-01

132

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

NASA Astrophysics Data System (ADS)

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.

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

133

Thermal Studies of the Dibutyltin(IV) Complexes of Schiff Bases Derived from Amino Acids  

Microsoft Academic Search

The thermal decomposition using TG, DTG and DTA, of seven complexes of the types Bu2SnL(I) and Bu2SnL(II) (where H2L(I)=Schiff base derived from acetylacetone and glycine [H2L-1(I)] or L-leucine [H2L-4(I)] or methionine [H2L-5(I)] or phenylglycine [H2L-6(I)]; H2L(II)=Schiff base derived from o-hydroxynaphthaldehyde and ?-alanine [H2L-2(II)] or DL-valine [H2L-3(II)] or L-leucine [H2L-4(II)] is shown to fall into one of two categories, viz, (1)

M. Nath; R. Yadav

1999-01-01

134

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

NASA Astrophysics Data System (ADS)

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).

Selvi, Canan; Nartop, Dilek

2012-09-01

135

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

PubMed

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

Selvi, Canan; Nartop, Dilek

2012-05-03

136

Efficient Oxidation of Hantzsch 1,4-Dihydropyridines with Tetrabutylammonium Peroxomonosulfate Catalyzed by Manganese(III) Schiff Base Complexes: The Effect of Schiff Base Complex on the Product Selectivity  

Microsoft Academic Search

Efficient and rapid oxidation of Hantzsch 1,4-dihydropyridine with tetrabutylammonium peroxomonosulfate (TBAO) is reported. The Mn(salophen)\\/monopersulfate catalytic system efficiently converts 1,4-dihydropyridines (DHPs) to their corresponding pyridine derivatives under mechanical stirring and microwave irradiation in CH2Cl2. The ability of various Schiff base complexes to oxidize DHPs was also investigated. The results showed that in the presence of manganese Schiff complex, no by-product

Masoud Nasr-Esfahani; Majid Moghadam; Ghasem Valipour

2009-01-01

137

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

138

Enantioselective catalytic epoxidation of styrenes by iodosylbenzene using chiral ruthenium(II) Schiff base complexes  

Microsoft Academic Search

Chiral ruthenium (II) Schiff base complexes 1–3 derived from l-histidine with salicylaldehyde, 5-chloro and 5-methoxy salicylaldehyde were prepared and used for catalytic enantioselective epoxidation of non-functionalised olefins, viz., styrene, 3-methyl-, 3-methoxy-, 3-chloro- and 3-nitrostyrene, with iodosylbenzene as an oxidant, giving the highest ee (80%) for nitro-styrene with catalyst 3. Each catalyst\\/substrate combination was examined under epoxidation conditions and the results

R. I. Kureshy; N. H. Khan; S. H. R. Abdi

1995-01-01

139

A Schiff-base porphyrin complex with double intramolecular hydrogen bonds  

Microsoft Academic Search

We have designed a porphyrin with a Schiff-base substituent as a model to study intramolecular hydrogen-bonding. The corresponding complex [Zn(SATPP)(CH3OH)] has been synthesized and characterized by X-ray crystallography, H NMR, and UV-Vis spectroscopy. The structure shows that there are three phenyl groups and one salicylideneaminophenyl group at the meso positions of the porphyrin, and the phenol oxygen is involved in

Wei Huang; Jiaxun Jiang; Zhiqiang Feng; Xiaoxu Kai; Chuanjiang Hu; Hong Yu; Wen Yang

2011-01-01

140

Solvent Effects on the Electrochemical Behavior of Iron(III) Schiff Base Complex  

Microsoft Academic Search

Electrochemical reduction of FeIIILCl where L is a Schiff base has been investigated in various aprotic solvents. From a plot of the half wave potential E1\\/2 for the reduction of these complexes vs. E1\\/2 for the oxidation of ferrocene, the solvent–solute interactions were studied: the E1\\/2 variation is found to be a function of Lewis-type acceptor–donor interactions. The diffusion coefficients

D. Ranchet; J. B. Tommasino; O. Vittori; P. L. Fabre

1998-01-01

141

Corrosion inhibition of mild steel with Schiff base compounds in 1 M HCl  

Microsoft Academic Search

The corrosion inhibition of mild steel with Schiff base compounds derived from salicylaldehyde and the corresponding amine was studied in relation to the concentration using electrochemical techniques. The maximum inhibition efficiency (?) was obtained for the N-(2-methyl phenyl)salicyaldimine compound with the three-electrochemical techniques applied. The N-(2-methyl phenyl)salicyaldimine and N-(2-methoxyphenyl)salicyaldimine compounds were seen to obey the Temkin adsorption isotherm whereas N-(2-hydroxyphenyl)salicyaldimine

Kaan C Emregül; O Atakol

2003-01-01

142

Synthesis and Characterization of Some Novel Amino Acid Schiff Base Fe(II) Complexes  

Microsoft Academic Search

New Fe(II) complexes of N?salicylidene? and N?naphthylideneamino acids (H2L) were prepared and characterized by elemental, electronic and IR spectral analyses, conductance and magnetic moment measurements and spectrophotometric determination of the stoichiometry. The stability and solubility of the prepared complexes were determined. The investigated Schiff bases exhibited monodentate divalent tridentate coordination and formed chelates of octahedral structures of the general formulae

Ali M. Shaker; Aida M. Awad; Lobna A. E. Nassr

2003-01-01

143

Hydrazone Schiff base-manganese(II) complexes: Synthesis, crystal structure and catalytic reactivity  

Microsoft Academic Search

Five dissymmetric tridentate Schiff base ligands, containing a mixed donor set of ONN and ONO were prepared by the reaction of benzhydrazide with the appropriate salicylaldehyde and pyridine-2-carbaldehyde and characterized by FT-IR, 1H and 13C NMR. The complexes of these ligands were synthesized by treating an ethanolic solution of the appropriate ligand and one equivalent Et3N with an equimolar amount

Omid Pouralimardan; Anne-Christine Chamayou; Christoph Janiak; Hassan Hosseini-Monfared

2007-01-01

144

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

PubMed

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(H(2)O)(4)](NO(3))(3), M=Cr(III) and Fe(III), [NiL(H(2)O)(4)](NO(3))(2), [ML(H(2)O)(2)](NO(3))(2), M=Zn(II) and Cd(II), [Cl(2)Pd(?-Cl)(2)PdL], [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 (1)H 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). PMID:23291195

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

2012-12-27

145

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

NASA Astrophysics Data System (ADS)

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).

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

2013-03-01

146

Titration of the bacteriorhodopsin Schiff base involves titration of an additional protein residue.  

PubMed

The retinal protein protonated Schiff base linkage plays a key role in the function of bacteriorhodopsin (bR) as a light-driven proton pump. In the unphotolyzed pigment, the Schiff base (SB) is titrated with a pK(a) of approximately 13, but following light absorption, it experiences a decrease in the pK(a) and undergoes several alterations, including a deprotonation process. We have studied the SB titration using retinal analogues which have intrinsically lower pK(a)'s which allow for SB titrations over a much lower pH range. We found that above pH 9 the channel for the SB titration is perturbed, and the titration rate is considerably reduced. On the basis of studies with several mutants, it is suggested that the protonation state of residue Glu204 is responsible for the channel perturbation. We suggest that above pH 12 a channel for the SB titration is restored probably due to titration of an additional protein residue. The observations may imply that during the bR photocycle and M photointermediate formation the rate of Schiff base protonation from the bulk is decreased. This rate decrease may be due to the deprotonation process of the "proton-releasing complex" which includes Glu204. In contrast, during the lifetime of the O intermediate, the protonated SB is exposed to the bulk. Possible implications for the switch mechanism, and the directionality of the proton movement, are discussed. PMID:15938637

Zadok, Uri; Asato, Alfred E; Sheves, Mordechai

2005-06-14

147

Synthesis, spectrochemical characterisation and catalytic activity of transition metal complexes derived from Schiff base modified chitosan.  

PubMed

Three novel quadridentate Schiff base complexes, [Cu(OIAC)Cl(2)], [Co(OIAC)Cl(2)] and [Ni(OIAC)Cl(2)] [OIAC, a Schiff base ligand: (([2-oxo-1H-indol-3-ylidene]amino)chitosan)] have been synthesized. The molecular structure of the complexes has been characterised by elemental analyses, magnetic measurements, molar conductance studies, vibrational (FT-IR), electronic (UV-Vis) and (1)H NMR spectroscopic techniques. Thermal properties of the complexes have been investigated with TG-DTG analyses. The surface morphological difference of ligand and the complexes has been explored with scanning electron microscopy. The crystallinity of the compounds was analysed by powder X-ray diffraction technique and it was found to be less for the Schiff base (OIAC) and the complexes as compared to the chitosan. The catalytic activities of the complexes have been studied in the oxidation of cyclohexane, using environmental friendly oxidant, hydrogen peroxide. Complex with rough surface has shown higher catalytic activity compared to the other complexes. PMID:23274227

Antony, R; Theodore David, S; Saravanan, K; Karuppasamy, K; Balakumar, S

2012-10-12

148

Synthesis, spectrochemical characterisation and catalytic activity of transition metal complexes derived from Schiff base modified chitosan  

NASA Astrophysics Data System (ADS)

Three novel quadridentate Schiff base complexes, [Cu(OIAC)Cl2], [Co(OIAC)Cl2] and [Ni(OIAC)Cl2] [OIAC, a Schiff base ligand: (([2-oxo-1H-indol-3-ylidene]amino)chitosan)] have been synthesized. The molecular structure of the complexes has been characterised by elemental analyses, magnetic measurements, molar conductance studies, vibrational (FT-IR), electronic (UV-Vis) and 1H NMR spectroscopic techniques. Thermal properties of the complexes have been investigated with TG-DTG analyses. The surface morphological difference of ligand and the complexes has been explored with scanning electron microscopy. The crystallinity of the compounds was analysed by powder X-ray diffraction technique and it was found to be less for the Schiff base (OIAC) and the complexes as compared to the chitosan. The catalytic activities of the complexes have been studied in the oxidation of cyclohexane, using environmental friendly oxidant, hydrogen peroxide. Complex with rough surface has shown higher catalytic activity compared to the other complexes.

Antony, R.; Theodore David, S.; Saravanan, K.; Karuppasamy, K.; Balakumar, S.

2013-02-01

149

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

PubMed

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, (1)H 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 (51)V 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. PMID:22387685

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

2012-02-10

150

Simple generation of cationic aluminum alkyls and alkoxides based on the pendant arm tridentate schiff base.  

PubMed

The prepared in situ methyl(chloro)aluminum complex (2) from Me2AlCl and the pendant arm tridentate Schiff base (H-SchNMe2) was used to generate the methylaluminum cationic species [(SchNMe2)AlMe]+ in further reaction with 1 equiv of AlCl3 or NaBPh4 as the chloride abstracting reagents. The exposure of the resulting methylaluminum cationic species to an excess of dry dioxygen at 0 degrees C afforded the alkoxyaluminum cationic species, [(SchNMe2)AlOMe]+ or [(SchNMe2)AlOPh]+. The alkoxylaluminum cations proved to be a very efficient catalyst in the polymerization of epsilon-caprolactone. PMID:15360224

Lewi?ski, Janusz; Horeglad, Pawe?; Dranka, Maciej; Justyniak, Iwona

2004-09-20

151

1 H NMR, IR and UV\\/VIS Spectroscopic Studies of Some Schiff Bases Derived From 2-Aminobenzothiazole and 2Amino3-hydroxypyridine  

Microsoft Academic Search

By condensing 2-aminobenzothiazole with 2-hydroxy-1-naphthaldehyde, 2-hydroxybenzaldehyde, 4-methoxybenzaldehyde, 4-hydroxybenzal-dehyde, benzaldehyde and 4-dimethylaminobenzaldehyde, and five Schiff bases Ia-Ie are prepared. Also, two Schiff bases IIa and IIb are prepared by condensation of 2-amino-3-hydroxypyridine with 2-hydroxy-1-naphthaldehyde and 2-hydroxybenzaldehyde. The 1H NMR, IR and UV\\/Vis spectra of these seven Schiff bases are investigated. The signals of the 1 HN MR spectra as well as

Raafat M. Issa; Abdalla M. Khedr; Helen Rizk

152

Factors affecting the C=N stretching in protonated retinal Schiff base: a model study for bacteriorhodopsin and visual pigments  

SciTech Connect

Factors affecting the C=N stretching frequency of protonated retinal Schiff base (RSBH/sup +/) were studied with a series of synthetic chromophores and measured under different conditions. Interaction of RSBH/sup +/ with nonconjugated positive charges in the vicinity of the ring moiety or a planar polyene conformation (in contrast to the twisted retinal conformation in solution) shifted the absorption maxima but did not affect the C=N stretching frequency. The latter, however, was affected by environmental perturbations in the vicinity of the Schiff base linkage. Diminished ion pairing achieved either by substituting a more bulky counteranion or by designing models with a homoconjugation effect lowered the C=N stretch energy. Decreasing solvation of the positively charged nitrogen leads to a similar trend. These effects in the vicinity of the Schiff base linkage also perturb the deuterium isotope effect observed upon deuteriation of the Schiff base. The results are interpreted by considering the mixing of the C=N stretching and C=N-H bending vibration. The C=N mode is shifted due to electrostatic interaction with nonconjugated positive charges in the vicinity of the Schiff base linkage, an interaction that does not influence the isotope effect. Weak hydrogen bonding between the Schiff base linkage in bacteriorhodopsin (bR) and its counteranion or, alternatively, poor solvation of the positively charged Schiff base nitrogen can account for the C=N stretching frequency of 1640 cm/sup -1/ and the deuterium isotope effect of 17 cm/sup -1/ observed in this pigment. Conversion of bR to the photochemically induced intermediate K/sub 610/ involves environmental perturbation in the vicinity of the C=N linkage, lowering the C=N stretch energy.

Baasov, T.; Friedman, N.; Sheves, M.

1987-06-02

153

Carbonyl compound dependent hydrolysis of mono-condensed Schiff bases: A trinuclear Schiff base complex and a mononuclear mixed-ligand ternary complex of copper(II)  

Microsoft Academic Search

Two Schiff bases, HL1 and HL2 have been prepared by the condensation of N-methyl-1,3-propanediamine (mpn) with salicylaldehyde and 1-benzoylacetone (Hbn) respectively. HL1 on reaction with Cu(ClO4)2·6H2O in methanol produced a trinuclear CuII complex, [(CuL1)3(?3-OH)](ClO4)2·H2O·0.5CH2Cl2 (1) but HL2 underwent hydrolysis under similar reaction conditions to result in a ternary CuII complex, [Cu(bn)(mpn)ClO4]. Both complexes have been characterised by single-crystal X-ray analyses,

Subrata Naiya; Biswarup Sarkar; You Song; Sandra Ianelli; Michael G. B. Drew; Ashutosh Ghosh

2010-01-01

154

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

NASA Astrophysics Data System (ADS)

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.

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

2012-09-01

155

Metal complexes of Schiff base derived from sulphametrole and o-vanilin  

Microsoft Academic Search

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] (H2L) 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 [M2X3(HL)(H2O)5]·yH2O (where M=Mn(II), Co(II), Ni(II), Cu(II), Zn(II)

Gehad G. Mohamed; Carmen M. Sharaby

2007-01-01

156

Interactions of Schiff-base ligands with gold nanoparticles: structural, optical and electrocatalytic studies.  

PubMed

A study on optical and electrochemical properties resulting upon interaction of Schiff base ligands with gold nanoparticles is presented. The measurements of the optical absorption and fluorescence properties have provided important information about structure-properties dependence. We show that in function of the isomer structure and its attachment orientation with respect to the metal nanoparticle, their optical properties can be modulated. Nanoparticle assemblies mediated by 3,4-DHS were also obtained based on a control of the interparticle interactions and their electrocatalytic activity toward NADH oxidation was investigated. PMID:21311788

Abad, Jose María; Revenga-Parra, Mónica; García, Tania; Gamero, Miriam; Lorenzo, Encarnación; Pariente, Félix

2011-02-10

157

The Protonation-Deprotonation Kinetics of the Protonated Schiff Base in Bicelle Bacteriorhodopsin Crystals  

PubMed Central

In the recently published x-ray crystal structure of the “bicelle” bacteriorhodopsin (bbR) crystal, the protein has quite a different structure from the native and the in cubo bacteriorhodopsin (cbR) crystal. Instead of packing in parallel trimers as do the native membrane and the cbR crystals, in the bbR crystal the protein packs as antiparallel monomers. To date, no functional studies have been performed, to our knowledge, to investigate if the photocycle is observed in this novel protein packing structure. In this study, both Raman and time-resolved transient absorption spectroscopy are used to both confirm the presence of the photocycle and investigate the deprotonation-reprotonation kinetics of the Schiff base proton in the bbR crystal. The observed rates of deprotonation and reprotonation processes of its Schiff base have been compared to those observed for native bR under the same conditions. Unlike the previously observed similarity of the rates of these processes for cbR crystals and those for native bacteriorhodopsin (bR), in bbR crystals the rate of deprotonation has increased by 300%, and the rate of reprotonation has decreased by nearly 700%. These results are discussed in light of the changes observed when native bR is delipidated or monomerized by detergents. Both the change of the hydrophobicity of the environment around the protonated Schiff base and Asp85 and Asp96 (which could change the pKa values of proton donor-acceptor pairs) and the water structure in the bbR crystal are offered as possible explanations for the different observations.

Sanii, Laurie S.; Schill, Alex W.; Moran, Cristin E.; El-Sayed, Mostafa A.

2005-01-01

158

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

PubMed

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

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

2011-08-04

159

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

PubMed Central

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.

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

2011-01-01

160

Oxovanadium(IV) and Niobium(V) Complexes with Some New Schiff Bases  

Microsoft Academic Search

Complexes of the type [VO(LH)(H2O)] and [Nb(LH)2Cl3], where LH = a singly deprotonated Schiff base derived from condensation of 3-substituted-4-amino-5-mercapto-l,2,4-triazole with benzoin were synthesized in ethanol or dry chloroform, respectively. A coordination number of five for the oxovanadium(IV) and seven for the niobium(V) complexes have been proposed on the basis of analytical, molar conductance, magnetic, IR and H NMR spectral

G. M. Shashidhara; T. R. Goudar

2000-01-01

161

Uranium(VI) Complexes of Some Schiff Bases Derived from Hydroxyaromatic Aldehyde and Ketone  

Microsoft Academic Search

Stable uranyl(II) complexes of some Schiff bases derived from 1,2-diaminoethane with bis-salicylaldehyde (H2L1) and\\/or bis-o-hydroxy-acetophenone (H2L2) as well as 2-aminophenol with salicylaldehyde (H2L3) and o-hydroxyacetophenone (H2L4) have been prepared. The complexes have been characterized by elemental analysis, spectral (UV-Visible, IR and NMR) studies as well as magnetic measurements. IR specral data suggest that the neutral molecules (H2L3 and H2L4) are

A. Z. El-sonbati; M. A. Diab; A. A. El-asmy

1989-01-01

162

Reductive transformations of Schiff bases in the synthesis of functionally substituted heteroaromatic amines  

Microsoft Academic Search

Schiff bases synthesized by condensation of 5- and 6-aminoquinolines, 5-amino-2-methylquinoline, nitroanilines, and pyrimidinylaminoanilines\\u000a with substituted benzaldehydes and pyridinecarbaldehydes were reduced with sodium tetrahydridoborate in acetic acid to obtain\\u000a the corresponding N-aryl(hetaryl)benzylamines, N-(pyridylmethyl)anilines, and N-(1,2,3,4-tetrahydroquinolyl)benzylamine derivatives. The reduction of arylhetarylimines with hydrazine hydrate in the presence\\u000a of Raney nickel involved only the azomethine C=N bond, while the nitrogen-containing heteroaromatic ring remained

Zh. V. Ignatovich; A. P. Kadutskii; E. V. Koroleva; A. V. Baranovskii; K. N. Gusak

2009-01-01

163

A schiff-based colorimetric fluorescent sensor with the potential for detection of fluoride ions.  

PubMed

A simple Schiff-based colorimetric fluorescent receptor 1 was prepared. It exhibits a "turn-on-type" mode with high sensitivity in the presence of F(-). The change in color is very easily observed by the naked eye in the presence of F(-), whereas other anions do not induce such a change. Job plot indicated a 1:2 complexation stoichiometry between receptor 1 and F(-). The association constant for 1-F(-) in CH3CN was determined as 1.32*10(5) M(-2) by a Hill plot. PMID:23888325

Huang, Cheng-Yin; Wan, Chin-Feng; Chir, Jiun-Ly; Wu, An-Tai

2013-07-27

164

The crystal structures and electrochemical studies of two naphthalenic Schiff base copper(II) complexes  

Microsoft Academic Search

The Schiff base ligands, 2-hydroxy-N-cyclohexyl-l-naphthaldimine (I), and 3-hydroxy-N-cyclohexyl-2-naphthaldimine (II), and their corresponding CuII complexes (1–2) respectively were synthesized and characterized. The crystal and molecular structures of bis-{(cyclohexyl)[(2-oxo-1H-naphth-1-ylidene)-methyl]aminato}copper(II) (1) and bis-{(cyclohexyl)[(3-oxo-2H-naphth-2-ylidene)-methyl]aminato} copper(II) (2), were determined. The X-ray diffraction study shows that the geometry around the metal atom for (1), is stepped square planar with a step of 1.063 Å while for

Ma. del Rocío Patiño-Maya; Rubén A. Toscano; Luis Velasco; Martha Otero-López; Martha Aguilar-Martínez

1997-01-01

165

Synthesis, DNA binding, and antimicrobial studies of novel metal complexes containing a pyrazolone derivative Schiff base  

Microsoft Academic Search

A novel series of Co(II), Ni(II), Cu(II), Zn(II), and VO(IV) complexes has been synthesized from the Schiff base derived from\\u000a 4-[(3,4-dimethoxybenzylidene)amino]-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one and 1,2-diaminobenzene. Structural features\\u000a were determined by analytical and spectral techniques. Binding of synthesized complexes with calf thymus DNA (CT DNA) was\\u000a studied by spectroscopic methods and viscosity measurements. Experimental results indicate that the complexes are able to\\u000a form

Natarajan Raman; Ramaraj Jeyamurugan; Mariyyappan Subbulakshmi; Raja Boominathan; Chithu Ramakrishnan Yuvarajan

2010-01-01

166

Anion directed templated synthesis of mono- and di-Schiff base complexes of Ni(II)  

Microsoft Academic Search

Two sets of Schiff base ligands, set-1 and set-2 have been prepared by mixing the respective diamine (1,2-propanediamine or 1,3-propanediamine) and carbonyl compounds (2-acetylpyridine or pyridine-2-carboxaldehyde) in 1:1 and 1:2 ratios, respectively and employed for the synthesis of complexes with Ni(II) perchlorate and Ni(II) thiocyanate. Ni(II) perchlorate yields the complexes having general formula [NiL2](ClO4)2 (L=L1 [N1-(1-pyridin-2-yl-ethylidine)-propane-1,3-diamine] for complex 1, L2

Shouvik Chattopadhyay; Michael G. B. Drew; Ashutosh Ghosh

2007-01-01

167

Synthesis, structural characterisation and electrochemical and antibacterial studies of Schiff base copper complexes  

Microsoft Academic Search

Neutral complexes of CuII have been synthesised from the Schiff bases derived from salicylidene-4-aminoantipyrine and PhNH2\\/substituted anilines. The structural features have been determined from their microanalytical, i.r., u.v.–vis., 1H-, 13C-n.m.r., mass and e.s.r. spectral data. All the complexes exhibit square-planar geometry. Their magnetic susceptibility measurements and low conductance data provide evidence for the monomeric and non-electrolytic natures of the complexes

Natarajan Raman; Antonysamy Kulandaisamy; Chinnathangavel Thangaraja; Paramasivan Manisankar; Subramanian Viswanathan; Chinnapayan Vedhi

2004-01-01

168

Synthesis, characterization, catalytic, electrochemical and thermal properties of tetradentate Schiff base complexes  

Microsoft Academic Search

In this study, the Schiff base ligands H2L1–H2L3 and their CuII, CoII, NiII, FeIII RuIII and VOIV complexes have been prepared and characterized by spectroscopic and analytical techniques. All the complexes are mononuclear.\\u000a Keto-enol tautomeric forms of the ligands have been investigated in polar and apolar solvents. The ligands favor the keto-form\\u000a in the C7H8 and C6H14. The C–C coupling

Nihal Deligönül; Mehmet Tümer; Selahattin Serin

2006-01-01

169

Electrochemical studies of copper(II) complexes with Schiff-base ligands  

Microsoft Academic Search

The electrochemical reduction of copper(II) complexes with salen Schiff-base ligands derived from ethylenediamine or (R,R) or (S,S)-1,2-diphenylethylenediamine and 5-methoxy, 5-bromo and 5-nitrosalicylaldehyde have been studied by cyclic voltammetry in the potential range +1 to ?2.3 V in dimethyl sulfoxide (DMSO) as a solvent. The resulting voltammograms consist of a single quasi-reversible one-electron transfer attributable to the couple [Cu(II)L]\\/[Cu(I)L]?. Trends in

Santiago Zolezzi; Evgenia Spodine; Antonio Decinti

2002-01-01

170

The inhibition of mild steel corrosion in hydrochloric acid media by two Schiff base compounds  

Microsoft Academic Search

Schiff bases of 2-({-1-methyl-3-[(2-sulfanylphenyl)imino]butylidene}-amino)-1-benzenethiol and 2-({-1,2-diphenyl-2-[(2-sulfanylphenyl)imino]ethylidene}amino)-1-benzenthiol\\u000a are investigated as corrosion inhibitors in acid solution. Polarization, electrochemical impedance spectroscopy, and weight\\u000a loss measurements were performed on mild steel in 15% HCl with and without the inhibitors. A significant decrease in the corrosion\\u000a rate of mild steel was observed in the presence of investigated inhibitors. Polarization curves indicate that both compounds\\u000a are

M. Behpour; S. M. Ghoreishi; A. Gandomi-Niasar; N. Soltani; M. Salavati-Niasari

2009-01-01

171

Synthesis, spectral and redox properties of metal complexes of macrocyclic tetraaza chiral Schiff bases  

Microsoft Academic Search

New transition metal(II) coordination compounds of tetraaza macrocyclic chiral Schiff bases, derived from 2-hydroxybenzylideneacetylacetone or 4-hydroxybenzylideneacetylacetone and (1R, 2R)-(-)-1,2-diaminocyclohexane, have been prepared and characterised spectroscopically and electrochemically. E.p.r. spectral data for the CuII complexes reveal a strong metal-to-ligand p-interaction in their square-planar configuration and the broadening of the g? component is due to the strain created by 1R and 2R

Sankaran Srinivasan; Periakaruppan Athappan; Gurusamy Rajagopal

2001-01-01

172

Schiff bases of increasing complexity as mild steel corrosion inhibitors in 2 M HCl  

Microsoft Academic Search

The effect of three Schiff base compounds with increasing number of coordination sites, namely, 2-{(E)-[(2-hydroxyethyl)imino]methyl} phenol (I), 2-[(E)-({2-[(2-hydroxyethyl)amino]ethyl}imino)methyl]phenol (II) and 2,2?-{iminobis[ethane-2,1-diylnitrilo(E)methylylidene]}diphenol (III) have been investigated at 298K by weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The inhibition efficiencies obtained from all methods employed are in good agreement. Results show compound III to be the best inhibitor

Canan Küstü; Kaan C. Emregül; Orhan Atakol

2007-01-01

173

Synthesis, crystal structure and imine bond activation of a copper(II) Schiff base complex  

Microsoft Academic Search

A new copper(II) complex [Cu(HL)(ClO4)](ClO4) (1), where HL is a multidentate Schiff base N,N?-(2-hydroxypropane-1,3-diyl)bis(pyridine-2-aldimine), is prepared, structurally characterized by X-ray crystallography and its spectral and electrochemical properties studied. The complex forms a one-dimensional chain in the solid state structure in which the monomeric {Cu(HL)} units are linked by the perchlorate ligand. The complex has an axially elongated six coordinate geometry

Arindam Mukherjee; Munirathinam Nethaji; Akhil R. Chakravarty

2004-01-01

174

Assessing p-Glycoprotein (Pgp) Activity In Vivo Utilizing 68 Ga–Schiff Base Complexes  

Microsoft Academic Search

Purpose  The p-glycoprotein (Pgp) is the most prominent member of active drug transporters leading to a multidrug-resistant phenotype.\\u000a For identification of tumors functionally overexpressing Pgp in vivo, non-invasive imaging techniques are needed.\\u000a \\u000a \\u000a \\u000a \\u000a Procedures  Six Schiff base compounds were synthesized and labeled with 68Ge\\/68Ga generator-derived 68Ga. The compounds were studied in vitro in Pgp-positive tumor cells. The property of being a Pgp substrate

Marco Fellner; Wolfgang Dillenburg; Hans-Georg Buchholz; Nicole Bausbacher; Mathias Schreckenberger; Franz Renz; Frank Rösch; Oliver Thews

175

Asymmetrical Schiff bases as inhibitors of mild steel corrosion in sulphuric acid media  

Microsoft Academic Search

Two newly synthesised Schiff bases [H2A3, N,N?-ortho-phenylene(salicylaldimine-acetylacetone imine) and H2A4, N,N?-ortho-phenylene(salicylaldimine-2-hydroxy-1-naphthaldimine)] were studied as inhibitors for the corrosion of mild steel in 0.5moldm?3 sulphuric acid. Results of weight loss, electrochemical impedance and Tafel polarisation measurements consistently identify both compounds as good inhibitors, with efficiencies of around 95% at a concentration of 400ppm. The inhibition is in both cases of a

Mirghasem Hosseini; Stijn F. L Mertens; Mohammed Ghorbani; Mohammed R Arshadi

2003-01-01

176

Oxovanadium (IV) complexes of bidentate [N,O] donor Schiff-base ligands: synthesis and mesomorphism  

Microsoft Academic Search

A series of new oxovanadium(IV) Schiff-base complexes of the type [VO(L)2], [L?=?N-(4-n-alkoxysalicylaldimine)-4?-dodecyloxyaniline, n?=?6, 8, 16, and 18] have been synthesized. The compounds were characterized by FT-IR, H-NMR, C-NMR, UV-Vis, FAB-mass, and magnetic susceptibility measurements. The mesomorphic behavior of the compounds was studied by polarized optical microscopy and differential scanning calorimetry. The compounds are all highly thermally stable exhibiting smectic mesomorphism.

Chira R. Bhattacharjee; Chitraniva Datta; Gobinda Das; Paritosh Mondal

2012-01-01

177

Enolic Schiff-base aluminum complexes and their application in lactide polymerization  

Microsoft Academic Search

A series of NNOO-tetradentate enolic Schiff-base ligands were prepared where ligand L1=bis(benzoylacetone)propane-1,2-diimine, L2=bis(acetylacetone)-propane-1,2-diimine, L3=bis-(acetylacetone)cyclohexane-1,2-diimine. Their further reaction with aluminum tris(ethyl) formed complexes LAlEt (1a, 2a and 3a). The solid structure of complexes 1a, 2a and 3a confirmed by X-ray single crystal analysis manifested that these complexes were all monomeric and five-coordinated with an aluminum atom in the center. The configurations

Xuan Pang; Xuesi Chen; Hongzhi Du; Xianhong Wang; Xiabin Jing

2007-01-01

178

Synthesis of a Novel Fluorescent Schiff Base as a Possible Cu(II) Ion Selective Sensor  

Microsoft Academic Search

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\\u000a (2-HNA) was synthesized and characterized by FT-IR, UV-vis, and 1H and 13C-NMR techniques. Photoluminescent properties of 2-HNA were investigated in different solvents including methanol, THF, DMF,\\u000a DMSO, acetone, acetonitrile, and dichloromethane. 2-HNA was found to have higher emission intensity and Stoke’s shift value\\u000a (??ST) in methanol solution. Relative emission intensity changes

Mehmet Y?ld?r?m; ?smet Kaya

2010-01-01

179

Single molecule magnetism in a ?-phenolato dinuclear lanthanide motif ligated by heptadentate Schiff base ligands.  

PubMed

The heptadentate Schiff base ligand, 2-(2-hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazoline (H(3)api), yields [Ln(2)api(2)] species when combined with lanthanide salts under basic conditions. A survey of the magnetic properties of this dinuclear lanthanide motif (Ln = Gd, Tb, Dy, Ho) has identified weak magnetic exchange, antiferromagnetic in nature for the isotropic gadolinium analogue, while single molecule magnetic behaviour is displayed in the case of the anisotropic dysprosium complex. PMID:22968859

Nematirad, Melina; Gee, William J; Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S; Batten, Stuart R

2012-09-12

180

Effect of Schiff base ligand on the size and the optical properties of TiO2 nanoparticles  

NASA Astrophysics Data System (ADS)

The effect of a Schiff-base ligand (N,N?-ethylenebis(acetylacetone iminato)dianion = acacen) on size and optical properties of TiO2 nanoparticles in a two-step sol-gel method was investigated. Different amounts of Schiff-base ligand were applied and the as-prepared products were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrum, Electron Dispersive X-ray spectroscopy (EDX) and ultraviolet-visible (UV-Vis) spectroscopy. Molecular orbital structure of acacen was calculated by density functional theory (DFT) in order to determine the exact orbital energies and electron transfer pathways. The results demonstrated that applying the appropriate amount of Schiff-base ligand could be effective in particle size control.

Masjedi, Maryam; Mir, Noshin; Noori, Elham; Gholami, Tahereh; Salavati-Niasari, Masoud

2013-10-01

181

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

PubMed Central

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.

Singh, Har Lal; Varshney, A. K.

2006-01-01

182

Synthetic, structural, and biochemical studies of organotin(IV) with Schiff bases having nitrogen and sulphur donor ligands.  

PubMed

Three bidentate Schiff bases having nitrogen and sulphur donor sequences were prepared by condensing S-benzyldithiocarbazate (NH(2)NHCS(2)CH(2)C(6)H(5)) 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 ((1)H, (13)C, and (119)Sn) 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

Singh, Har Lal; Varshney, A K

2006-03-14

183

The inhibitive effect of some bis-N,S-bidentate Schiff bases on corrosion behaviour of 304 stainless steel in hydrochloric acid solution  

Microsoft Academic Search

The inhibition effect of four new Schiff bases on the corrosion of 304 stainless steel in 1M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. Polarization curves indicated that all studied Schiff bases act as mixed type (cathodic\\/anodic) inhibitors. The adsorption of the inhibitors was well described by the Langmuir adsorption isotherm and the

M. Behpour; S. M. Ghoreishi; N. Soltani; M. Salavati-Niasari

2009-01-01

184

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

SciTech Connect

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.

Bondar, A.N. [University of California, Irvine; Suhai, Sandor [German Cancer Research Center, Heidelberg; Fischer, S. [University of Heidelberg; Smith, Jeremy C [ORNL; Elstner, Marcus [Technical University of Braunschweig

2006-10-01

185

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

SciTech Connect

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.

Bondar, A.N. [University of California, Irvine; Suhai, Sandor [German Cancer Research Center, Heidelberg; Fischer, S. [University of Heidelberg; Smith, Jeremy C [ORNL; Elstner, Marcus [Technical University of Braunschweig

2007-03-01

186

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

SciTech Connect

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.

Bondar, A.N. [University of California, Irvine; Suhai, Sandor [German Cancer Research Center, Heidelberg; Fischer, S. [University of Heidelberg; Smith, Jeremy C [ORNL; Elstner, Marcus [Technical University of Braunschweig

2007-03-01

187

Novel Y(III) PVC-Based Membrane Microelectrode Based on a New S–N Schiff's Base  

Microsoft Academic Search

A new Schiff's base with sulfur and nitrogen donor atoms (2-({(E)-1,2-diphenyl-2-[(2-2-sulfanylphenyl)imino]ethylidene}amino)-1-benzenethiol, DSAB) was used as a membrane-active component to prepare a Y(III)-selective polymeric membrane microelectrode. The electrode exhibits a Nernstian response toward Y(III) ions over a wide concentration range (1.0 × l0–1.0 × 10 M), with a detection limit of 7.0 × l0 M (6.2 µg\\/mL). It has a very fast response time <5 s and can be used for at

Mohammad Reza Ganjali; Azadeh Daftari; Parviz Nourozi; Masoud Salavati-Niasari

2003-01-01

188

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

PubMed Central

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.

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

2013-01-01

189

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

PubMed

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, (1)H NMR, (13)C 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

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

2013-04-07

190

Metal-based biologically active compounds: synthesis, spectral, and antimicrobial studies of cobalt, nickel, copper, and zinc complexes of triazole-derived schiff bases.  

PubMed

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

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

2011-12-19

191

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

PubMed Central

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.

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

2011-01-01

192

Chiral Ru(II) Schiff base complex-catalysed enantioselective epoxidation of styrene derivatives using iodosyl benzene as oxidant. II  

Microsoft Academic Search

Six-coordinated chiral Ru(II) Schiff base complexes of the type [RuLX(Y)2] where L=terdentate chiral Schiff bases derived from l-tyrosine, l-phenylalanine with salicylaldehyde, 3-tertiary-butyl-, 3,5-di-tertiary-butyl-, 3,5-dichloro- and 3,5-dinitrosalicylaldehyde, X=PPh3 and Y=H2O have been investigated as catalysts for enantioselective epoxidation of styrene, 4-chloro-, 4-nitro- and 4-methylstyrene in fluorobenzene in order to explore the efficiency of catalytic system by varying the substituents on the

R. I Kureshy; N. H Khan; S. H. R Abdi; S. T Patel; P Iyer

1999-01-01

193

Syntheses, spectroscopic, and magnetic properties of polystyrene-anchored coordination compounds of tridentate ONO donor Schiff base  

Microsoft Academic Search

The crosslinked chloromethylated polystyrene (PSCH2–Cl) reacts with the Schiff base, derived from condensation of PSCH2–Cl with 3-formylsalicylic acid and salicylhydrazide to form a polystyrene-anchored Schiff base, PSCH2–LH3 (1). Compound 1 reacts with a number of metal ions to form polystyrene-anchored coordination compounds, PSCH2–LHM?·?DMF (where M?=?Cu, Zn, Cd, UO2, and MoO2), PSCH2–LHM??·?3DMF (where M??=?Mn, Co, and Ni), PSCH2–LHFeCl?·?2DMF, and PSCH2–LHZr(OH)2?·?2DMF. The

Dinesh Kumar; Praveen Kumar Gupta; Amit Kumar; Durga Dass; Arun Syamal

2011-01-01

194

Spectroscopic and biological studies of mono- or binuclear complexes derived from thio-Schiff bases of some transition metals  

Microsoft Academic Search

Two novel Schiff base ligands, 4,6-bis((E)-1-(2-mercaptophenylimino)ethyl)benzene-1,3-diol, H4La, and 1,2-((E)-1-(6-((E)-1-(2-mercaptophenylimino)ethyl)pyridine-2-yl)ethylideneamino)benzenthiol, H2Lb, have been synthesized by the condensation of 4,6-diacetyl resorcinol (DAR) or 2,6-diacetyl pyridine (DAP) with 2-aminobenzenthiol (ABT), in the molar ratio 1:2 [1 (DAR or DAP):2 ABT]. The structures of ligands were elucidated by elemental analysis, infrared (IR), UV–VIS as well as H-NMR. Reaction of the Schiff base ligands with

Azza A. A. Abou-Hussein

2010-01-01

195

Protection of mild steel corrosion with Schiff bases in 0.5 M H 2SO 4 solution  

Microsoft Academic Search

Three new Schiff bases, viz., N,N?-ethylen-bis (salicylidenimine) [S1], N,N?-isopropylien-bis (salicylidenimine) [S2], and N-acetylacetone imine, N?-(2-hydroxybenzophenone imine) ortho-phenylen [S3] have been investigated as corrosion inhibitors for mild steel in 0.5M H2SO4 using Tafel polarization and electrochemical impedance spectroscopy (EIS). The three Schiff bases function as good inhibitors reaching inhibition efficiencies of ?97–98% at 300ppm concentration. The fraction of the metal surface

M. G. Hosseini; M. Ehteshamzadeh; T. Shahrabi

2007-01-01

196

The synthesis, characterization, electrochemical character, catalytic and antimicrobial activity of novel, azo-containing Schiff bases and their metal complexes  

Microsoft Academic Search

Three novel Schiff base ligands containing the azo group, 2-((E)-(4-((E)-phenyldiazenyl)phenylimino)methyl)phenol, 3-((E)-(4-((E)-phenyldiazenyl)phenylimino)methyl)benzene-1,2-diol and 4-((E)-(4-((E)-phenyldiazenyl)phenylimino)methyl)benzene-1,2,3-triol, were synthesized from the reaction of p-aminoazobenzene with salicylaldehyde, 2,4-dihydroxybenzaldehyde and 2,3,4-trihydroxybenzaldehyde, respectively. The mononuclear Co(II) and Cu(II) complexes of the Schiff base ligands were prepared and characterized using elemental analyses, IR, UV–visible spectroscopy, magnetic susceptibility and conductance measurements; 1H NMR and mass spectra of the ligands

Esin ?spir

2009-01-01

197

Synthesis, structural characterization, and DFT studies of new mixed-ligand iron(III) Schiff-base complexes  

Microsoft Academic Search

Cationic iron(III) Schiff-base aquo complex of the type [FeL(H2O)2]NO3 (L = C12H18N2O2) was accessed from the interaction of Fe(NO3)3 ? 9H2O with the [N2O2] donor Schiff base. Reaction of the aquated complex with bifluoride , thiocyanate (SCN), or azide in 1 : 2 molar ratio in methanolic medium led to the synthesis of anionic mixed-ligand complexes, [FeLX2] (L = C12H18N2O2,

Chira R. Bhattacharjee; Pankaj Goswami; Paritosh Mondal

2010-01-01

198

Corrosion inhibition efficiency and surface activity of benzothiazol-3-ium cationic Schiff base derivatives in hydrochloric acid  

Microsoft Academic Search

Two series of cationic Schiff base surfactants namely: 2-(benzylideneamino)-3-(2-oxo-2-alkoxyethyl)-1,3-benzothiazol-3-ium bromide and 2-[(4-methoxybenzylidene)amino]-3-(2-oxo-2-alkoxyethyl)-1,3-benzothiazol-3-ium bromide were prepared and confirmed using elemental analysis, FTIR, and 1H NMR spectra. The surface activity of the synthesized Schiff bases showed their tendency towards adsorption at the interfaces. The prepared compounds were evaluated as corrosion inhibitors for carbon steel in 0.5M HCl solution using gravimetric and polarization

N. A. Negm; Y. M. Elkholy; M. K. Zahran; S. M. Tawfik

2010-01-01

199

Ruthenium(II) unsymmetrical N2O2 tetradentate Schiff-base complexes: synthesis, characterization, and catalytic studies  

Microsoft Academic Search

A series of six-coordinate ruthenium(II) complexes [Ru(CO)(L)(B)] (B = PPh3, AsPh3 or Py; L= unsymmetrical tetradentate Schiff base, x = 5–8; L= salen-2-hyna, L= Cl-salen-2-hyna, L= valen-2-hyna, L= o-hyac-2-hyna) have been prepared by reacting [RuHCl(CO)(EPh3)2(B)] (E = P or As) with unsymmetrical Schiff bases in benzene under reflux. The new complexes have been characterized by analytical and spectroscopic (infrared, electronic,

S. Gowri; M. Muthukumar; S. Krishnaraj; P. Viswanathamurthi; R. Prabhakaran; K. Natarajan

2010-01-01

200

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

PubMed

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

Joseyphus, R Selwin; Nair, M Sivasankaran

2008-06-30

201

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

PubMed Central

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.

Joseyphus, R. Selwin

2008-01-01

202

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

PubMed Central

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 µg/ml.

Sakthivel, A.; Rajasekaran, K.

2007-01-01

203

Functionalization of mesoporous silica membrane with a Schiff base fluorophore for Cu(II) ion sensing.  

PubMed

A Schiff base (SB) immobilized hybrid mesoporous silica membrane (SB-HMM) was prepared by immobilizing a Schiff base onto the pore surface of mesoporous silica (pore size=3.1 nm) embedded in the pores of a porous anodic alumina membrane. In contrast to the non-fluorescent analogous SB molecule in homogeneous solutions, SB-HMM exhibited intense fluorescence due to emission enhancement caused by aggregation of SB groups on the pore surface. The high quantum efficiency of the surface SB groups allows SB-HMM to function as a fluorescent sensor for Cu(II) ions in an aqueous solution with good sensitivity, selectivity and reproducibility. Under the optimal conditions described, the linear ranges of fluorescence intensity for Cu(II) are 1.2-13.8(M (R(2)=0.993) and 19.4-60 (R(2)=0.992) (M. The limit of detection for Cu(II) is 0.8 ?M on basis of the definition by IUPAC (C(LOD)=3.3S(b)/m). PMID:21621037

Chen, Xiaotong; Yamaguchi, Akira; Namekawa, Manato; Kamijo, Toshio; Teramae, Norio; Tong, Aijun

2011-04-14

204

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

PubMed Central

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 µg/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 µg/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.

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

2013-01-01

205

Cation removal using cellulose chemically modified by a Schiff base procedure applying green principles.  

PubMed

Pentane-2,4-dione (acetylacetone) molecules were covalently incorporated under several different conditions to ethylene-1,2-diamine (en)-modified cellulose, using polar solvents or without solvents. The quantitative amount of en incorporated was given from 0.37+/-0.01 to 3.03+/-0.01 mmol of nitrogen per gram of cellulose, depending on the synthetic routes and after Schiff base formation this percentage was reduced by 1.38-6.12%. The synthetic routes indicated that lower solvent volumes produced higher amounts of en incorporation. However, the highest degree of pendant groups on the polymeric cellulose structure was obtained from a solvent-free reaction route. This procedure was applied for synthesizing all Schiff bases, causing a decrease in the amount of nitrogen. The available basic centers on the best covalently bonded biopolymer were investigated for adsorption of divalent copper, cobalt, nickel, and zinc from aqueous solution, with a capacity order of Cu2+ > Co2+ > Ni2+ > Zn2+. PMID:19748100

da Silva Filho, Edson C; de Melo, Júlio C P; da Fonseca, Maria G; Airoldi, Claudio

2009-08-12

206

Enolic schiff base aluminum complexes and their catalytic stereoselective polymerization of racemic lactide.  

PubMed

A series of enolic Schiff base aluminum(III) complexes LAlR (where L=NNOO-tetradentate enolic Schiff base ligand) containing ligands that differ in their steric and electronic properties were synthesized. Their single crystals showed that these complexes are five-coordinated around the aluminum center. Their coordination geometries are between square pyramidal and trigonal bipyramidal. Their catalytic properties in the solution polymerization of racemic lactide (rac-LA) were examined. The modifications in the auxiliary ligand exhibited a dramatic influence on the catalytic performance. Lengthening the backbone from C(2) alkylene to C(3) alkylene resulted in remarkable enhancement of both the stereoselectivity and the polymerization rate because of the increasing flexibility of the diimine backbone. Electron-withdrawing substituents in the diketone also highly improved the activity and the stereoselectivity. Among these complexes, 4 b had the highest activity and the stereoselectivity owing to the C(3) alkylene backbone and the two gem-methyl groups on the middle carbon atom. The value of the polymerization rate constant (k(p)) catalyzed by 4 b in 70 degrees C was 1.90 L mol(-1) min(-1), the activation energy of the polymerization (35.4 kJ mol(-1)) was calculated according to the Arrhenius equation. Other factors that influenced the polymerization, such as the polymerization time, the temperature, and the monomer concentration, are also discussed in detail. PMID:18232044

Pang, Xuan; Du, Hongzhi; Chen, Xuesi; Wang, Xianhong; Jing, Xiabin

2008-01-01

207

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

NASA Astrophysics Data System (ADS)

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.

Hanif, Muhammad; Chohan, Zahid H.

2013-03-01

208

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

NASA Astrophysics Data System (ADS)

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.

Devi, Jai; Batra, Nisha; Malhotra, Rajesh

2012-11-01

209

Corrosion inhibition efficiency of nonionic Schiff base amphiphiles of p-aminobenzoic acid for aluminum in 4N HCL  

Microsoft Academic Search

A novel series of self-assembled nonionic Schiff base amphiphiles was synthesized and their chemical structures were confirmed using elemental analysis, FTIR spectroscopy and 1H NMR spectra. The surface activities of these amphiphiles were determined based on the data of surface and interfacial tension, critical micelle concentration, effectiveness, efficiency, maximum surface excess and minimum surface area. Thermodynamics of adsorption and micellization

Nabel A. Negm; Mohamed F. Zaki

2008-01-01

210

Simulation of cis- trans photoinduced transitions IB bis-Schiff base molecules  

NASA Astrophysics Data System (ADS)

Quantum chemical and molecular dynamics simulations of photoinduced UV-absorption and circular dichroism of a new synthesized symmetrical-base derived from condensation of two mole 5-(4-diethylamino-phenyl)-penta-2,4-dienal with a chiral diamine were performed. Photoinduced changes from trans- to cis-isomers in chromophore and transitions between the trans-trans and cis-cis isomers corresponding to right- and left-enantiomers through the metastable cis-trans conformation may explain the observed spectral measurements. The crucial role in the observed transitions is played by C?C bonds close to the benzyl planes of the bis-based molecules (bis-Schiff base, BSB). At the same time rotation of the benzoate rings (about 110°) seems to be important. The performed simulations show that among the calculational technique Adamo-Barone DFT method gave better agreement with experiment.

Lemercier, G.; Alexandre, M.; Andraud, C.; Kityk, I. V.

2004-03-01

211

Synthesis and Characterization of Cobalt(II) and Nickel(II) Complexes of Some Schiff Bases Derived from 3-hydrazino-6-methyl[1,2,4] triazin-5(4H)one  

Microsoft Academic Search

Cobalt(II) and nickel(II) complexes of bidentate and tridentate Schiff bases derived from the condensation of 3-hydrazino-6-methyl[1,2,4]triazin-5(4H)one\\u000a and aromatic aldehyde derivatives were synthesized and characterized. Elemental and thermal analyses as well as i.r., electronic\\u000a spectra, molar conductance and magnetic moment measurements were utilized for the investigation of the complexes. From these\\u000a investigation data, the structural formulae, the mode of bonding, and

Ahmed H. Osman

2006-01-01

212

Rapid and efficient oxidative decarboxylation of carboxylic acids with sodium periodate catalyzed by manganese (III) Schiff base complexes.  

PubMed

Rapid and efficient oxidative decarboxylatoin of alpha-aryl carboxylic acids was observed. In the chemical system containing Mn(III)-salophen complex as catalyst, carboxylic acids are converted efficiently to the corresponding carbonyl derivatives with sodium periodate. The ability of various Schiff base complexes in the oxidative decarboxylation of carboxylic acids was also investigated. PMID:14980602

Mirkhani, Valiollah; Tangestaninejad, Shahram; Moghadam, Majid; Moghbel, Maryam

2004-03-01

213

Synthesis, Spectroscopic and Antimicrobial Studies of Lead(II) Complexes of Schiff Bases Derived From Amino Acids and Isatins  

Microsoft Academic Search

A new series of lead(II) complexes have been synthesized with Schiff bases derived from isatins and amino acids. These ligands act as bidentate species and coordinate to the metal atom through the azomethine nitrogen and carboxylate oxygen atom via deprotonation. The synthesized complexes have been characterized by elemental analysis, conductance measurements and molecular weight determinations. The mode of bonding of

Har Lal Singh; J. B. Singh; H. Sachedva

2012-01-01

214

Unsymmetrical salen-type ligands: high yield synthesis of salen-type Schiff bases containing two different benzaldehyde moieties  

Microsoft Academic Search

Salen-type Schiff base ligands incorporating two different benzylidene moieties and a diamine backbone were synthesized in high yield (80–90%) under mild conditions via a stepwise approach. In the first step, anhydrous hydrochloric acid was used to selectively protect one amino group of the vicinal diamine backbone. The resulting ammonium salt was added to a substituted benzaldehyde providing access to a

E. Joseph Campbell; SonBinh T Nguyen

2001-01-01

215

Investigation of Some Schiff Bases as Corrosion Inhibitors for Aluminium Alloy in 0.5 M Hydrochloric Acid Solutions  

NASA Astrophysics Data System (ADS)

The inhibitory effect of some Schiff bases viz. N,N?-bis(2-hydroxybenzylidene)-1,3-diaminobenzene (SB1), N,N?-bis(4-bromobenzylidene)-1,3-diaminobenzene (SB2) and N,N?-bis(2-hydroxy-5-bromobenzylidene)-1,3-diaminobenzene (SB3) on the corrosion of aluminium alloy in 0.5 M HCl acid have been studied using weight loss measurements, potentiodynamic polarization and Scanning Electron Microscopy (SEM). The experimental results showed that these Schiff bases SB1, SB2 and SB3 efficiently inhibit the corrosion of aluminium alloy in 0.5 M HCl medium and found to follow almost similar corrosion inhibition pattern. The potentiodynamic polarization curves revealed that, all the studied Schiff bases are mixed type inhibitors with a predominantly cathodic action and their inhibition efficiencies increased with increasing inhibitor concentration. The adsorption of Schiff bases was found to follow Langmuir adsorption isotherm. SEM study revealed that these compounds protect the metal corrosion by adsorption on its surface to form a protective layer. The inhibition performance depends strongly on the type of functional groups substituted on the benzene ring.

Muniandy, M. T.; Rahim, A. Abdul; Osman, H.; Shah, A. Mohd; Yahya, S.; Raja, P. Bothi

216

Infrared and Raman spectra of complexes about rare earth nitrate with Schiff base from o-vanillin and 1-naphthylamine  

Microsoft Academic Search

Infrared and Raman spectra are reported for 10 complexes of rare earth nitrate with Schiff base from o-vanillin (2-hydroxy-3-methoxy-benzaldehyde) and 1-naphthylamine in the range 100–4000 cm?1 and 100–1799 cm?1. Some absorption bands are assigned and the results of them are used to discuss the coordinated structure of the complexes.

Liu Guofa; Shi Tongshun; Zhao Yongnian

1997-01-01

217

Low temperature FTIR study of the Schiff base reprotonation during the M-to-bR backphotoreaction  

PubMed Central

We have applied low temperature difference FTIR spectroscopy to investigate intermediates produced from the M intermediate upon blue light excitation (<480 nm). In agreement with an earlier report by Balashov and Litvin (1981), who studied these intermediates with low temperature visible absorption spectrophotometry, we have observed at least three stages in this backphotoreaction. The initial photoproduct is stable at 100 K, and two products of subsequent thermal reactions are observed upon raising the temperature to 130 and 160 K, respectively. The alterations in the C=N stretching mode of the Schiff base have been identified by isotopically labeling the retinal chromophore, and changes in C=O stretching modes of amino acid residues with acidic side chains have been investigated. Analysis of the C=N stretching mode shows that the Schiff base remains unprotonated after the photochemical reaction at 100 K. Moreover, there are two types of Schiff bases, presumably associated with different bR species, that become thermally reprotonated at 130 and 160 K, respectively. Bands associated with the C=O stretching modes suggest that Asp 85 rather than Asp 96 reprotonates the Schiff base during the M to bR backphotoreaction. This conclusion is consistent with earlier observations that the polarity of electrical signals during this photochemical back reaction is reversed as compared to the thermal regeneration of bR from M.

Takei, H.; Gat, Y.; Sheves, M.; Lewis, A.

1992-01-01

218

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

PubMed

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 (1)H NMR spectra. The structures of the isolated solid complexes are proposed on the basis of the spectral and magnetic studies. PMID:17950027

Shoukry, Azza A; Shoukry, Mohamed M

2007-09-07

219

The complex extracellular domain regulates the deprotonation and reprotonation of the retinal Schiff base during the bacteriorhodopsin photocycle  

SciTech Connect

During the L {r_arrow} M reaction of the bacteriorhodopsin photocycle the proton of the retinal Schiff base is transferred to the anionic D85. This step, together with the subsequent reprotonation of the Schiff base form D96 in the M {r_arrow} N reaction, results in the translocation of a proton across the membrane. The first of these critical proton transfers occurs in an extended hydrogen-bonded complex containing two negatively charged residues (D85 and D212), two positively charged groups (the Schiff base and R82), and coordinated water. We simplified this region by replacing D212 and R82 with neutral residues, leaving only the proton donor and acceptor as charged groups. The D212N/R82Q mutant shows essentially normal proton transport, but in the photocycle neither of this protein nor of the D212N/R82Q/D96N triple mutant does a deprotonated Schiff base (the M intermediate) accumulate. Instead, the photocycle contains only the K, L, and N intermediates. Infrared difference spectra of D212N/R82Q and D212N/R82Q/D96N demonstrate that although D96 becomes deprotonated in N, D85 remains unprotonated. On the other hand, M is produced at pH>8, where according to independent evidence the L {leftrightarrow} M equilibrium should shift toward M. Likewise, M is restored in the photocycle when the retinal is replaced with the 14-fluoro analogue that lowers the pK{sub a} of the protonated Schiff base, and now D85 becomes protonated as in the wild type. We conclude from these results that the proton transfers to and from the Schiff base, and now D85 becomes protonated as in the wild type. We conclude form these results that the proton transfers to and from the Schiff base probably both occur after photoexcitation of D212N/R82Q, but the L {leftrightarrow} M and M {leftrightarrow} N equilibria are shifted away from M, and, untypically, D85 does not retain the proton it had gained. 72 refs., 11 figs., 1 tab.

Brown, L.S.; Varo, G.; Lanyi, J.K. [Univ. of California, Irvine, CA (United States)] [and others

1995-10-03

220

Mixed (phthalocyaninato)(Schiff-base) di-dysprosium sandwich complexes. Effect of magnetic coupling on the SMM behavior.  

PubMed

Reaction between Schiff-base ligand and half-sandwich complex M(Pc)(acac) led to the isolation of new sandwich-type mixed (phthalocyaninato)(Schiff-base) di-lanthanide compounds M2(Pc)2(L)H2O (M = Dy, Gd) (, ) [H2Pc = metal free phthalocyanine, Hacac = acetylacetone, H2L = N,N'-bis(3-methyloxysalicylidene)benzene-1,2-diamine] with the triple-decker molecular structure clearly revealed by single crystal X-ray diffraction analysis. For the comparative studies, sandwich triple-decker analogues with pure Schiff-base ligand M2(L)3H2O (M = Dy, Gd) (, ) were also prepared. Dynamic magnetic measurement result reveals the single-molecule magnet (SMM) nature of the di-dysprosium derivative , while the static magnetic investigation over both pure and the diamagnetic diluted samples of this compound discloses the interionic ferromagnetic coupling between the two dysprosium ions, which in turn effectively suppresses the QTM and enhances the energy barrier of this SMM. Nevertheless, comparative studies over the static magnetic properties of the di-dysprosium triple-decker complexes and indicate the stronger magnetic coupling between the two lanthanide ions in mixed (phthalocyaninato)(Schiff-base) species than in the pure Schiff-base triple-decker analogue, suggesting the special coordination sphere around the dysprosium ions in the former compound over the latter one on the more intense inter-ionic ferromagnetic coupling. As a very small step towards understanding the structure-property relationship, the present result will be surely helpful for the design and synthesis of the multinuclear lanthanide-based SMMs with good properties. PMID:24005576

Wang, Hailong; Liu, Chenxi; Liu, Tao; Zeng, Suyuan; Cao, Wei; Ma, Qi; Duan, Chunying; Dou, Jianmin; Jiang, Jianzhuang

2013-10-15

221

Biological activity studies on metal complexes of novel tridentate Schiff base ligand. Spectroscopic and thermal characterization.  

PubMed

Metal complexes of novel Schiff base (HL) ligand, prepared via condensation of 4-aminoantipyrine and 2-aminophenol, are prepared. The ligand is characterized based on elemental analysis, mass, IR and (1)H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, (1)H NMR, solid reflectance, magnetic moment, molar conductance, ESR spectra and thermal analyses (TG, DTG and DTA). From the elemental analyses, 1:1 [M]:[ligand] complexes are prepared with the general formulae [M(L)Cl(H(2)O)(2)] x yH(2)O (M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II), y = 3-4), [Fe(L)Cl(2)(H(2)O)] x 3 H(2)O and [Th(L)Cl(H(2)O)(2)]Cl(2) x 3 H(2)O. The molar conductance data reveal that all the metal chelates are non-electrolytes (except Th(IV) complex, it is 2:1 electrolyte). 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 phenolic-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 are calculated from the DTG curves using Coats-Redfern method. The synthesized ligand, in comparison to its metal complexes is screened for its antibacterial activity against bacterial species, Escherichia coli, Pseudomonas putida, Exiguobacterium acetylicum and Bacillus simplex. 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. PMID:19758728

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

2009-08-06

222

"Test kit" for detection of biologically important anions: a salicylidene-hydrazine based Schiff base.  

PubMed

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 H(2)PO(4)(-), Cl(-), Br(-), I(-), NO(3)(-), NO(2)(-), HSO(4)(-), HSO(3)(-), and ClO(4)(-) in aqueous-acetonitrile solvent. The colorimetric test results and UV-vis spectral analysis are in well agreement with (1)H NMR titration results in d(6)-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. PMID:23220673

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

2012-11-01

223

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

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

224

Dihydroxycoumarin Schiff base synthesis and structure determination from powder diffraction data  

NASA Astrophysics Data System (ADS)

The titled compound with systematic name 4-hydroxy-3-((E)-1-(2-((E)-1-(4-hydroxy-2-oxo-2H-chromen-3-yl)ethylideneamino)ethylimino) ethyl)-2H-chromene-2-one is a new tetradentate (ONNO) Schiff-base which was synthesized by condensation of ethylenediamine and 3-acethyl 4-hydroxycoumarin. Its crystal structure was ab initio determined from laboratory X-ray powder diffraction data by using the direct space approach. The structure is monoclinic with space group P21/n and unit cell parameters a = 10.4153(4) Å, b = 12.8319(4) Å, c = 7.48229(15) Å, ? = 98.892(3) Å, V = 987.97(5) Å3. The asymmetric part of the structure contains one half of the centrosymmetric molecule. The obtained product was also characterized by infrared, UV-VIS and 1H NMR spectroscopy.

Rohlí?ek, Jan; Ketata, Imen; Ayed, Taïcir Ben; Hassen, Rached Ben

2013-11-01

225

Synthesis, Spectra and Electrochemistry of Ru(III) Complexes with Tetradentate Schiff Bases  

Microsoft Academic Search

A series of low-spin ruthenium(III) complexes of the type [RuX(EPh3)(LL')] (X = Cl, Br; E = P, As; LL' = Salen, Salpn and Saldien) have been synthesised by reacting [RuCl3(PPh3)3], [RuCl3(AsPh3)3], [RuBr3(AsPh3)3] or [RuBr3(PPh3)2(MeOH)] with tetradentate Schiff bases such as bis(salicylaldehyde)ethylenediimine (H2-Salen), bis(salicylaldehyde)propylenediimine (H2-Salpn) and bis(salicylaldehyde)diethylenetriimine (H2-Saldien). All complexes have been characterized by elemental analyses, IR and electronic spectra, EPR,

R. Ramesh; P. K. Suganthy; K. Natarajan

1996-01-01

226

Synthesis and characterization of two oxovanadium (IV) Schiff base complexes derived from amino acids and pyridoxal  

Microsoft Academic Search

Two N-pyridoxylideneamino acidato complexes of oxovanadium (IV), [VO(pyr-D,L-Met)(bipy)] and [VO(pyr-D,L-Thr)(bipy)]?H2O with Schiff bases, made from amino acids (DL-methionine and DL-threonine) and pyridoxal, were prepared by an amine-diffusion reaction and characterized by single crystal X-ray diffraction. Both [VO(pyr-D,L-Met)(bipy)] and [VO(pyr-D,L-Thr)(bipy)]?H2O crystallize in triclinic P-1 with cell parameters a=9.2605(19) Å, b=12.851(3) Å, c=19.079(4) Å, ?=92.34(3)°, ?=93.20(3)°, ?=91.03(3)°, V=2264.7(8) Å3, Z=2, and a=9.4513(8) Å, b=11.9026(13) Å, c=12.7589(12) Å, ?=66.836(6)°, ?=87.171(6)°,

Huijuan Yue; Dong Zhang; Zhan Shi; Shouhua Feng

2006-01-01

227

Electrochemical and X-ray studies of nickel(II) Schiff base complexes derived from salicylaldehyde  

Microsoft Academic Search

The oxidative chemistry of three Ni(II) complexes with Schiff base ligands derived from salicylaldehyde and diamines with different steric demands, N,N?-2-methylpropane-2,3-diyl-bis(salicylideneiminate)nickel(II) (1), N,N?-1,2-cyclohexyl-1,2-dyil-bis(salicylideneiminate)nickel(II) (2) and N,N?-2,3-dimethylbutane-2,3-diyl-bis(salicylideneiminate)nickel(II) (3), was studied by cyclic voltammetry and chronoamperometry in N,N?-dimethylformamide and (CH3)2SO. The electrogenerated species were characterised by EPR spectroscopy. All three complexes exhibited metal-centred oxidised processes and the oxidised products were low-spin six-coordinate

I. C Santos; M Vilas-Boas; M. F. M Piedade; C Freire; M. T Duarte; B de Castro

2000-01-01

228

Synthesis, molecular docking and biological evaluation of Schiff base transition metal complexes as potential urease inhibitors.  

PubMed

Six transition metal compounds of Schiff base ligands were evaluated for the inhibitory activity on jack bean urease, of which compounds 2-6 were determined by single crystal X-ray analysis. It was found that copper(II) complexes 1 and 4 showed strong inhibitory activity against jack bean urease (IC(50) = 0.52 and 0.46 microM), compared with acetohydroxamic acid (IC(50) = 42.12 microM) as a positive reference. Cobalt(II), nickel(II) and zinc(II) compounds also exhibited potent inhibitory activity (IC(50) = 3.88-25.20 microM). A docking analysis using the AUTODOCK 4.0 program could explain the inhibitory activities of 1 and 4 against urease. PMID:20691510

Chen, Wu; Li, Yuguang; Cui, Yongming; Zhang, Xian; Zhu, Hai-Liang; Zeng, Qingfu

2010-07-14

229

Preparation and characterization of new tetradentate Schiff base metal complexes and biological activity evaluation  

NASA Astrophysics Data System (ADS)

A new Schiff base (N,N?-ethylene (bis 1-cyclopropyl-6-fluoro-4-oxo-7-(piperazine-1-yl)-quinoline-3-carboxylic acid) and its Zn(II), Zr(IV), Ce(IV) and U(VI) complexes were synthesized and characterized by elemental analysis, molar conductance, IR, UV-Vis, 1H NMR spectra, magnetic moment, thermal analysis as well as mass spectra. The IR results demonstrate that the tetradentate binding mode of the ligand involving azomethine nitrogen and carboxylato oxygen atoms. The calculated bond length and the bond stretching force constant, F(UO), values for UO2 bond are 1.744 Å and 654.49 N m-1. The antimicrobial activity of the synthesized ligand and its complexes were screened and the results showed that the metal complexes were found to be more active than free ligand.

Sadeek, S. A.; El-Attar, M. S.; Abd El-Hamid, S. M.

2013-11-01

230

Synthesis, characterization and biological studies of sulfonamide Schiff's bases and some of their metal derivatives.  

PubMed

A new series of Schiff base ligands derived from sulfonamide and their metal(II) complexes [cobalt(II), copper(II), nickel(II) and zinc(II)] have been synthesized and characterized. The nature of bonding and structure of all the synthesized compounds has been explored by physical, analytical and spectral data of the ligands and their metal(II) complexes. The authors suggest that all the prepared complexes possess an octahedral geometry. The ligands and metal(II) complexes have been screened for their in vitro antibacterial activity against bacterial strains, Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi and for antifungal activity against fungal strains, Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glabrata. These assays enabled the identification of the metal complexes as an effective antimicrobial agent with low cytotoxicity. PMID:21534864

Chohan, Zahid H; Shad, Hazoor A; Supuran, Claudiu T

2011-05-03

231

Aluminum complexes of sterically hindered tetradentate Schiff bases: Synthesis, structure, and reactivity toward ?-caprolactone  

Microsoft Academic Search

The sterically hindered Schiff bases tbmSalenH2 [tbmSalen = N,N?-1,2-ethylenebis(3-tert-butyl-5-methylsalicylideneimine)] and tbmSalcenH2 [tbmSalcen = N,N?-trans-1,2-cyclohexanediyl-bis(3-tert-butyl-5-methylsalicylideneimine)] afforded a series of aluminum complexes of the general formulae [Al(tbmSalen)X] and [Al(tbmSalcen)X] (X = Cl, Me, Et). The molecular structure of [Al(tbmSalcen)Cl] was determined by single-crystal X-ray structural analysis which revealed a five-coordinate aluminum center with a distorted square pyramidal geometry. The alkyl complexes were

Insa Taden; Hak-Chul Kang; Werner Massa; Jun Okuda

1997-01-01

232

Formation of a silicon-containing macrocycle with a pyridoxalimine Schiff base ligand.  

PubMed

The reaction of dichlorodiphenylsilane with a polydentate Schiff base ligand derived from pyridoxal and 2-hydroxyaniline yields the macrocyclic centrosymmetric silicon compound 9,27-dimethyl-3,3,21,21-tetraphenyl-2,4,20,22-tetraoxa-8,13,26,31-tetraaza-3,21-disilapentacyclo[30.4.0.0(6,11).0(14,19).0(24,29)]hexatrideca-1(32),6,8,10,12,14,16,18,24,26,28,30,33,35-tetradecaene-10,28-diol chloroform tetrasolvate, C(52)H(44)N(4)O(6)Si(2) x 4CHCl(3). The asymmetric unit contains half of the macrocycle and two molecules of chloroform, with C-H...O and C-H...N contacts binding the two guests to the host in the crystal structure. This macrocyclic silicon compound represents a promising host for molecular-recognition processes and for the construction of nanostructures. PMID:19057073

Böhme, Uwe; Günther, Betty; Schwarzer, Anke

2008-11-14

233

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

NASA Astrophysics Data System (ADS)

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 ?–? stacking interaction within the structural rows, inducing larger intermolecular distances resulting in quite different functional physical and chemical properties.

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

2013-10-01

234

Photoresponse of the protonated Schiff-base retinal chromophore in the gas phase.  

PubMed

The fragmentation, initiated by photoexcitation as well as collisionally-induced excitation, of several retinal chromophores was studied in the gas phase. The chromophore in the protonated Schiff-base form (RPSB), essential for mammalian vision, shows a remarkably selective photoresponse. The selectivity of the gas-phase chromophore is triggered by a series of fast trans to cis isomerizations followed by a Diels-Alder cyclization with subsequent slow statistical fragmentation, leading to one specific fragment ion. The pattern of the final statistical fragmentation may be altered by chemical modifications of the chromophore. We propose that isomerizations play an important role in the photoresponse of gas-phase retinal chromophores and guide internal conversion through conical intersections. The role of protein interactions is then to control the specificity of the photoisomerization in the primary step of vision and possibly to diminish thermal noise by suppressing spontaneous isomerization by heat. PMID:24142109

Toker, Y; Rahbek, D B; Kiefer, H V; Rajput, J; Antoine, R; Dugourd, P; Nielsen, S Brøndsted; Bochenkova, A V; Andersen, L H

2013-10-30

235

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

NASA Astrophysics Data System (ADS)

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.

Hasnain, Sumaiya; Nishat, Nahid

236

A new Schiff base based on vanillin and naphthalimide as a fluorescent probe for Ag+ in aqueous solution  

NASA Astrophysics Data System (ADS)

A new Schiff base based on vanillin and naphthalimide was designed and synthesized as fluorescent probe. The probe showed high selectivity for Ag+ over other metal ions such as Pb2+, Na+, K+, Cd2+, Ba2+, Cr3+, Zn2+, Cu2+, Ni2+, Ca2+, Al3+ and Mg2+ in aqueous solution. A new fluorescence emission was observed at 682 nm in the presence of Ag+ ion. The fluorescence intensity quenched with increasing the concentration of Ag+ at 682 nm. The method of job's plot confirmed the 1:2 complex between Ag+ and probe, and the mechanism was proposed.

Zhou, Yanmei; Zhou, Hua; Ma, Tongsen; Zhang, Junli; Niu, Jingyang

2012-03-01

237

Proton transport by proteorhodopsin requires that the retinal Schiff base counterion Asp-97 be anionic.  

PubMed

At pH >7, proteorhodopsin functions as an outward-directed proton pump in cell membranes, and Asp-97 and Glu-108, the homologues of the Asp-85 and Asp-96 in bacteriorhodopsin, are the proton acceptor and donor to the retinal Schiff base, respectively. It was reported, however [Friedrich, T. et al. (2002) J. Mol. Biol., 321, 821-838], that proteorhodopsin transports protons also at pH <7 where Asp-97 is protonated and in the direction reverse from that at higher pH. To explore the roles of Asp-97 and Glu-108 in the proposed pumping with variable vectoriality, we compared the photocycles of D97N and E108Q mutants, and the effects of azide on the photocycle of the E108Q mutant, at low and high pH. Unlike at high pH, at a pH low enough to protonate Asp-97 neither the mutations nor the effects of azide revealed evidence for the participation of the acidic residues in proton transfer, and as in the photocycle of the wild-type protein, no intermediate with unprotonated Schiff base accumulated. In view of these findings, and the doubts raised by absence of charge transfer after flash excitation at low pH, we revisited the question whether transport occurs at all under these conditions. In both oriented membrane fragments and liposomes reconstituted with proteorhodopsin, we found transport at high pH but not at low pH. Instead, proton transport activity followed the titration curve for Asp-97, with an apparent pK(a) of 7.1, and became zero at the pH where Asp-97 is fully protonated. PMID:12767242

Dioumaev, Andrei K; Wang, Jennifer M; Bálint, Zoltán; Váró, György; Lanyi, Janos K

2003-06-01

238

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

PubMed

Novel Schiff base (H(2)L, 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 (1)H-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]·xH(2)O (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. PMID:23266605

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

2012-11-15

239

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

NASA Astrophysics Data System (ADS)

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 n·H 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.

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

2004-01-01

240

Spectroscopic and density functional theory investigation of novel Schiff base complexes  

NASA Astrophysics Data System (ADS)

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.

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

2013-02-01

241

Selective inhibition of the unfolded protein response: targeting catalytic sites for Schiff base modification.  

PubMed

Constitutive protein misfolding in the endoplasmic reticulum (ER) can lead to cellular toxicity and disease. Consequently, the protein folding environment within the ER is highly optimised and tightly regulated by the unfolded protein response (UPR). The apparent convergence of myriad diseases upon proteostasis in the ER has triggered a broad effort to identify selective inhibitors of the UPR. In particular, the most ancient component of this cellular stress pathway, the transmembrane protein IRE1, represents an appealing target for pharmacological intervention. Several inhibitors of IRE1 have recently been reported, each containing an aldehyde moiety that forms an unusual, highly selective Schiff base with a single key lysine (K907) within the RNase domain. Here we review the progress made in chemical genetic manipulation of IRE1 and the unfolded protein response and discuss computational strategies to rationalise the selectivity of covalently active small molecules for their targets. As an exemplar, we provide additional evidence that K907 of IRE1 is buried within a particularly unusual environment that facilitates Schiff base formation. New free-energy calculations within a molecular dynamics (MD) simulation framework show that the pKa of K907 is reduced by ?3.6 pKa units, relative to the model pKa of lysine in water. This significant pKa perturbation provides additional insights into the precise requirements for inhibition and for RNase catalysis by IRE1. Our computational method may represent a general approach for identifying potential covalent inhibitory lysine sites within buried protein cavities. PMID:23884086

Tomasio, Susana M; Harding, Heather P; Ron, David; Cross, Benedict C S; Bond, Peter J

2013-08-27

242

New Schiff Bases Containing Silicon and Their Co(II) and Cu(II) Complexes: Synthesis, Complexation, Characterization, and Antimicrobial and Electrochemical Properties  

Microsoft Academic Search

Two novel Schiff base ligands, 4-((3-(trimethoxysilyl)propylimino)methyl)benzene– 1,2,3-triol (LH) and 4-((3-(triethoxysilyl)propylimino)methyl)benzene–1,2,3-triol (LH), have been synthesized by the reaction of 2,3,4-trihydroxybenzaldehyde with 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane, respectively. The mononuclear Co and Cu complexes of these Schiff bases were prepared. The complexes of the Schiff bases are formed by coordination of N, O atoms of the ligands. The proposed structures were confirmed by elemental

E. ?spir

2009-01-01

243

Synthesis, spectral characterization, catalytic and antibacterial studies of new Ru(III) Schiff base complexes containing chloride\\/bromide and triphenylphosphine\\/arsine as co-ligands  

Microsoft Academic Search

A new Ru(III) Schiff base complexes of the type [RuX(EPh3)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 [RuX3(EPh3)3] with appropriate Schiff base ligands in benzene in the 2:1 stoichiometric ratio. The new complexes have been characterized by analytical,

S. Arunachalam; N. Padma Priya; C. Jayabalakrishnan; V. Chinnusamy

2009-01-01

244

Comparative kinetics of carboxylic esters hydrolysis catalyzed by the zinc(II) complex of a macrocyclic Schiff base ligand  

Microsoft Academic Search

The comparative kinetic investigation of the hydrolysis of p-nitrophenyl picolinate (PNPP) and p-nitrophenyl acetate (PNPA) catalyzed by the tetracoordinate macrocyclic Schiff base complex of zinc(II) (1) at 30 °C is reported. The results indicate that the (1) catalyzed hydrolyses of PNPP and PNPA are acid-base catalytic processes and that the active species is the metal bound hydroxide ion, namely, ZnL—OH-.

Xingming Kou; Xiangguang Meng; Jiaqing Xie; Xiancheng Zeng

2003-01-01

245

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

Microsoft Academic Search

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

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

2011-01-01

246

The first example of intramolecular cycloaddition of carbene-derived azomethine ylides in a domino reaction of difluorocarbene with Schiff bases  

Microsoft Academic Search

Domino reactions of difluorocarbene with Schiff bases containing a tethered olefinic or acetylenic dipolarophile moiety involve intramolecular 1,3-dipolar cycloaddition of iminiodifluoromethanides and yield chromeno[4,3-b]pyrrole derivatives.

Mikhail S Novikov; Alexander F Khlebnikov; Olga V Besedina; Rafael R Kostikov

2001-01-01

247

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

PubMed

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 ((1)H, (13)C, and (29)Si) 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

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

2013-07-28

248

Manganese(III) Complexes of Some Amino Acid (L?Serine, L?Methionine, L?Cystein) Schiff Bases Derived From 2?Hydroxy?1?Naphthaldehyde  

Microsoft Academic Search

A new series of manganese(III) complexes of amino acid Schiff bases synthesized from 2?hydroxy?1?naphthaldehyde and L?serine, L?methionine and L?cystein. The structure of their metal complexes was investigated by elemental analyses, IR, TGA, magnetic susceptibility, and mass spectra. The structure of the N?naphthylidene amino acid Schiff bases were determined by IR, UV, H NMR and mass spectra for a comparison with

?ffet ?ak?yan; Hamza Y?lmaz

2003-01-01

249

Synthesis, spectroscopy, electrochemistry and thermal study of Ni(II) and Cu(II) unsymmetrical N2O2 Schiff base complexes.  

PubMed

The new tetradentate unsymmetrical N(2)O(2) Schiff base ligands, Ni(II) and Cu(II) complexes were synthesised and chracterized by IR, UV-vis, (1)H NMR and elemental analysis. The electrochemical properties of the Ni(II) complexes were investigated. The thermogravimetry of the Ni(II) and Cu(II) complexes were carried out in the range of 20-700 degrees C. Decomposition of synthesised complexes is related to the Schiff base characteristics. PMID:20594901

Kianfar, Ali Hossein; Keramat, Liala; Dostani, Morteza; Shamsipur, Mojtaba; Roushani, Mahmoud; Nikpour, Farzad

2010-06-11

250

Synthesis, Characterization, Redox, Catalytic, and Antibacterial Activities of Binuclear Ruthenium(III) Schiff Base Complexes Containing Triphenylphosphine as Co-Ligand  

Microsoft Academic Search

New hexa-coordinated binuclear Ru(III) Schiff base complexes of the type [(PPh3)2X2Ru]2L (where, X = Cl or Br; L = binucleating N2O2 Schiff bases) have been synthesized and characterized by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-vis, CH-NMR, ESR, cyclic voltammetric, SEM and powder X-ray diffraction pattern. The new complexes have been used as catalyst in C? C coupling reaction and

Arumugam Manimaran; Chinnasamy Jayabalakrishnan

2010-01-01

251

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.  

PubMed

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 (Pfefferlé, 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. PMID:1400394

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

1992-10-15

252

Design of molecular switching and signaling based on proton transfer in 2-hydroxy Schiff bases: a computational study.  

PubMed

The present work aims to exploit the possibility of using the tautomerism in 2-hydroxy Schiff bases for molecular switching. The enol imine (E)? enaminone (K) tautomerization in a series of 2-hydroxy Schiff bases have been investigated theoretically at the DFT/B3LYP/6-311G** level of theory. The intramolecular proton transfer processes have been explored, transition structures have been located and characterized. The kinetics and thermodynamics of the proton transfer process, and its time scale have been computed and discussed in the framework of the suitability as molecular switches. Substituent effects have been computed and its effect on the enthalpy changes (?H*) and activation energies (?G*) have been analyzed and discussed. Nonspecific solvent effects have also been taken into account by using the polarized continuum model (IPCM) of two different solvent. The tautomerization energies are decreased and hence the endothermic nature of the enol imine ? enaminone tautomerization. The potential energy barriers, on the other hand, are increased due to the relative destabilization of the transition states. The NBO charge populations show that there is a high positive charge on the hydrogen atom during the process in all cases, which confirms that the proton transfer proceeds through a three-center interaction. The proton transfer processes, in all cases studied are kinetically allowed. The low potential energy barrier suggests that interconversion between the two tautomeric forms is spontaneous and the two forms may coexist. PMID:22961622

Abood Hameed, Salem; Alrouby, Saaban K; Hilal, Rifaat

2012-09-09

253

Detection of trace amounts of Pb(II) by schiff base-chitosan-grafted multiwalled carbon nanotubes  

NASA Astrophysics Data System (ADS)

A simple, highly sensitive, accurate and selective method for determination of trace amounts of Pb(II) in water samples is presented. A novel Schiff base-chitosan-grafted multiwalled carbon nanotubes (S-CS-MWCNTs) solid-phase extraction adsorbent was synthesized by covalently grafting a Schiff base-chitosan (S-CS) onto the surfaces of oxidized MWCNTs. The stability of a chemically (S-CS-MWCNTs) especially in concentrated hydrochloric acid which was then used as a recycling and preconcentration reagent for further uses of (S-CS-MWCNTs). The method is based on selective chelation of Pb(II) on surfactant coated C18, modified with a Schiff base-chitosan-grafted multiwalled carbon nanotubes (S-CS-MWCNTs). The retained ions were then eluted with 4 mL of 4 M nitric acid and determined by flame atomic absorption spectrometry (FAAS) at 283.3 nm for Pb. The influence of flow rates of sample and eluent solutions, pH, break-through volume, effect of foreign ions on chelation and recovery were investigated. 1.5 g of surfactant coated C18 adsorbs 40 mg of the Schiff s base which in turn can retain 15.0 ± 0.9 mg of each of the two ions. The limit of detection (3?) for Pb(II) was found to be 3.20 ng L-1. The enrichment factor for both ions are 100. The mentioned method was successfully applied on determination of lead in different water samples. The ions were also speciated by means of three columns system.

Moghimi, Ali

2013-07-01

254

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)

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).

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

255

Synthesis and Crystal Structures of Ternary Copper(II) Complex Containing Salicylaldehyde Schiff Base and 4,4?Bipyridine  

Microsoft Academic Search

\\u000a Abstract  A new ternary mixed-ligand complex [Cu2(sal-glu)2(bipy)(H2O)2] · (H2O) (bipy = 4,4?-bipyridine and sal-glu = salicylaldehyde l-glutamic Schiff base) has been synthesized and characterized by X-ray diffraction. It crystallizes in the triclinic system,\\u000a space group P-1 with a = 9.6199(13) Å, b = 9.9111(13) Å, c = 9.9167(13) Å. The amino acid Schiff base coordinates to the Cu(II) ion in a tridentate mode including phenol-hydroxyl oxygen,\\u000a carboxyl oxygen and amide nitrogen atom, while the bipy coordinates

Xun Feng; Cheng-Zhi Xie; Li-Ya Wang; Yu-Fang Wang; Lu-Fang Ma

2008-01-01

256

Synthesis and antibacterial activities of metal(II) complexes with Schiff bases derived from 3,5-diiodosalicylaldehyde  

Microsoft Academic Search

Two new Schiff bases (2,4-diiodo-6-[(2-morpholin-4-yl-ethylimino)-methyl]-phenol and 2,4-diiodo-6-[(3-morpholin-4-yl-propylimino)-methyl]-phenol), condensed from 3,5-diiodosalicylaldehyde with 2-morpholinoethylamine and 3-morpholinopropylamine, have been designed and synthesized. Reaction of the Schiff bases with Zn(OAc)2 · 2H2O, Cu(OAc)2 · H2O, Ni(OAc)2 · 4H2O, Co(OAc)2 · 4H2O, Cd(OAc)2 · 2H2O, Mn(OAc)2 · 4H2O, Fe(SO4)2 · 7H2O, and Hg(OAc)2 led to the formation of 16 new mononuclear complexes. The complexes were

Suo-Ping Xu; Lei Shi; Peng-Cheng Lv; Rui-Qin Fang; Hai-Liang Zhu

2009-01-01

257

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

258

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

NASA Astrophysics Data System (ADS)

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.

Ceyhan, Gökhan; Çelik, Cumali; Uru?, Serhan; Demirta?, ?brahim; Elmasta?, Mahfuz; Tümer, Mehmet

2011-10-01

259

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

PubMed

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

Ceyhan, Gökhan; Çelik, Cumali; Uru?, Serhan; Demirta?, ?brahim; Elmasta?, Mahfuz; Tümer, Mehmet

2011-06-21

260

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

SciTech Connect

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.

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

2010-03-04

261

Effect of molecular conformation on spectroscopic properties of symmetrical Schiff bases derived from 1,4-phenylenediamine  

NASA Astrophysics Data System (ADS)

The relationship between the molecular conformation and spectroscopic properties of symmetrical bis-Schiff bases was explored experimentally. Seven samples of compounds p-X-C6H4CHNC6H4NCHC6H4-p-X (X = OMe, Me, Et, Cl, F, CF3, or CN) were prepared for this study, and their crystal structures were measured by X-ray diffraction. Their ?max values in ethanol, acetonitrile, chloroform and cyclohexane solvents were measured, and their ?C(CN) values in chloroform-d were determined. The results show that the ?max is dependent on the substituents at the benzylidene ring and the dihedral angle ? of the titled molecules, 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(CN). This study provides a new understanding for the molecular conformation on spectroscopic properties of symmetrical Schiff bases.

Fang, Zhengjun; Cao, Chenzhong

2013-03-01

262

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

PubMed Central

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.

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

2013-01-01

263

Rapid and efficient oxidation of Hantzsch 1,4-dihydropyridines with sodium periodate catalyzed by manganese (III) Schiff base complexes.  

PubMed

Rapid and efficient oxidation of Hantzsch 1,4-dihydropyridine with sodium periodate is reported. The Mn(III)-salophen/NaIO4 catalytic system converts 1,4-dihydropyridines to their corresponding pyridine derivatives at room temperature in a 1:1, CH3CN/H2O mixture. The ability of various Schiff base complexes in the oxidation of 1,4-dihydropyridine was also investigated. PMID:16377198

Nasr-Esfahani, Masoud; Moghadam, Majid; Tangestaninejad, Shahram; Mirkhani, Valiollah; Momeni, Ahmad Reza

2006-01-11

264

Synthesis, characterization and antimicrobial activity of transition metal complexes with the Schiff base derived from imidazole-2-carboxaldehyde and glycylglycine  

Microsoft Academic Search

The Co(II), Ni(II) and Cu(II) complexes of the Schiff base derived from imidazole-2-carboxaldehyde and glycylglycine were synthesized and characterized by elemental analysis, PMR, molar conductance, IR, electronic, magnetic measurements, ESR, redox properties, thermal studies, XRD and SEM. Conductance measurements indicate that the complexes are 1 : 1 electrolytes. IR data show that the ligand is tetradentate with imidazole nitrogen, azomethine

R. Selwin Joseyphus; M. Sivasankaran Nair

2009-01-01

265

Chiral Mn(III) Schiff base complex catalyzed aerobic enantioselective epoxidation of prochiral non-functionalized olefins  

Microsoft Academic Search

Dissymmetric Mn(III) chiral Schiff base complexes derived from 1R,2R(?)-1,2 diaminocyclohexane with 3-acetyl 4-hydroxy 6-methyl 2-pyrone and 2-hydroxy benzaldehyde, 5-chloro-, 5-methoxy-, 5-nitro-, 3-tertiary butyl- and 3,5 ditertiary butyl 2-hydroxy benzaldehyde have been prepared. Microanalysis, IR, UV\\/Vis spectroscopy, conductance measurement, optical rotation, CD spectroscopy and cyclic voltammetry accomplished the characterization of the complexes. These complexes were used for aerobic enantioselective epoxidation of

R. I. Kureshy; N. H. Khan; S. H. R. Abdi; P. Iyer; S. T. Patel

1999-01-01

266

Aggregation of RecA-derived peptides on single-stranded oligonucleotides triggered by schiff base-mediated crosslinking  

Microsoft Academic Search

We here show that single-stranded oligonucleotides containing 5-formyl-2?-deoxyuridine (fdU) can crosslink the peptides derived from the DNA binding site of RecA protein through a Schiff base formation. The ability of crosslinking of fdU-containing oligonucleotides was investigated using a series of peptides whose amino acid residues spanning the center of the RecA-derived peptide were sequentially replaced with lysine. Circular dichroism (CD)

Toru Sugiyama; Atsushi Kittaka; Hiroaki Takayama; Mitsugu Tomioka; Yoshiteru Ida; Reiko Kuroda

2003-01-01

267

Coordination Compounds of Organotin(IV) Chlorides with the Schiff Bases Derived from 2Hydroxy1-naphthaldehyde  

Microsoft Academic Search

Coordinative interactions of Ph2SnCl2, Me2SnCl2 and PhSnCl3 with 2-hydroxy-1-naphthalideneanilines containing different substituents in the aniline fragment have been studied. The newly synthesized adducts of 1:2 stoichiometry [organotin(IV) chloride: Schiff base] have been characterized by elemental analysis, thermogravimetric and infrared spectral data. Conductance measurements and electronic spectra indicate considerable dissociation of the compounds in solution.

T. N. Srivastava; A. K. S. Chauhan

1977-01-01

268

High-sensitivity neutron diffraction of membranes: Location of the Schiff base end of the chromophore of bacteriorhodopsin  

SciTech Connect

Three important events in the functional cycle of bacteriorhodopsin occur at the chromophore: the primary absorption of light, the isomerization from the all-trans to the 13-cis form, and the deprotonation and reprotonation of its Schiff base. The protonated Schiff base linkage of the chromophore with lysine-216 plays an essential role in the color regulation of the pigment and is most likely directly involved in the charge translocation of this light-driven proton pump. Although much is known about the structure of the protein, the position of this key functional group has not yet been determined. The authors have synthesized a retinal in which the five protons closest to the Schiff base are replaced by deuterons. The labeled retinal was spontaneously incorporated into bacteriorhodopsin by using a mutant of Halobacterium halobium that is deficient in the synthesis of retinal. The position of the labeled Schiff base end of the chromophore was determined in the two-dimensional projected density of dark-adapted bacteriorhodopsin by neutron diffraction. The result fits very well with their previous work using retinals that were selectively deuterated in the middle of the polyene chain or in the cyclohexene ring. A coherent structure emerges with the three labeled positions on one line, separated by distances that are in good agreement with the tilt angle of the polyene chain (about 20{degree}). The results show that it is possible to locate a small group containing as few as five deuterons in a membrane protein of molecular weight 27,000.

Heyn, M.P.; Westerhausen, J.; Wallat, I.; Seiff, F. (Freie Universitaet Berlin (West Germany))

1988-04-01

269

Electrochemical study on the effect of Schiff base and its cobalt complex on the acid corrosion of steel  

Microsoft Academic Search

The effect of the Schiff base N,N?-bis (salicylaldehyde)-1,3-diaminopropane (Salpr) and its corresponding cobalt complex on the corrosion behaviour of steel in 1M sulphuric acid solution were studied by electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization techniques. Spectrophotometry measurements were employed to investigate the stability of the complex in acid media. The inhibitive effect of Salpr and its stable octahedral cobalt

A. M. Abdel-Gaber; M. S. Masoud; E. A. Khalil; E. E. Shehata

2009-01-01

270

Synergistic effect of 1-dodecanethiol upon inhibition of Schiff bases on carbon steel corrosion in sulphuric acid media  

Microsoft Academic Search

Purpose – In this paper, the main aim is to study the synergistic effects of alkanethiols upon inhibition of Schiff bases, N,N?-ethylen-bis and N,N?-ortho-phenylen-bis in 0.5 M sulphuric acid solutions. Design\\/methodology\\/approach – Measurements were carried out in a three-electrode cell assembly connected to the corrosion measurement system using software for Tafel polarization. Impedance measurements were carried out at open circuit

Maryam Ehteshamzadeh; Taghi Shahrabi; Mirghasem Hosseini

2006-01-01

271

An investigation of some Schiff bases as corrosion inhibitors for austenitic chromium–nickel steel in H2SO4  

Microsoft Academic Search

The corrosion inhibition of austenitic chromium–nickel steel by two Schiff bases, N-(1-toluidine)salicylaldimine and N-(2-hydroxyphenyl)salicylaldimine, was investigated in sulphuric acid medium. The effect of concentration and temperature on inhibition properties was determined. It was found that when the concentrations of inhibitor were increased the inhibition efficiencies (?) and surface coverage (?) increased. Some thermodynamic parameters such as free energy of adsorption,

S. B?lg?ç; N. Çaliskan

2001-01-01

272

Spectral characterization, cyclic voltammetry, morphology, biological activities and DNA cleaving studies of amino acid Schiff base metal(II) complexes  

Microsoft Academic Search

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 N2O2 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

M. A. Neelakantan; F. Rusalraj; J. Dharmaraja; S. Johnsonraja; T. Jeyakumar; M. Sankaranarayana Pillai

2008-01-01

273

Novel poly-Schiff bases containing 4,4?-diamino-triphenylamine as hole transport material for organic electronic device  

Microsoft Academic Search

Two novel functional conjugated poly-Schiff bases containing triphenylamine unite were synthesized by condensation polymerization of 4,4?-biamine triphenylamine and dialdehydes in solution, which having conjugation throughout the molecule chain are soluble in both polar and nonpolar solvents, and the optical, electrochemical properties were studied by the UV–visible spectrum, photoluminescence (PL) spectrum and cyclic voltammetry(CV) technology. The optical band gaps were calculated

Hai-Jun Niu; Yu-Dong Huang; Xu-Duo Bai; Xin Li

2004-01-01

274

Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes  

Microsoft Academic Search

In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride

Mustafa Dolaz; Vickie McKee; Serhan Urus; Necmettin Demir; Ali E. Sabik; Aysegül Gölcü; Mehmet Tümer

2010-01-01

275

Synthesis, antiviral activity and cytotoxicity evaluation of Schiff bases of some 2-phenyl quinazoline-4(3)H-ones  

Microsoft Academic Search

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

Krishnan Suresh Kumar; Swastika Ganguly; Ravichandran Veerasamy; Erik De Clercq

2010-01-01

276

Exclusive fluoride ion recognition and fluorescence "turn-on" response with a label-free DMN Schiff base.  

PubMed

A label-free DMN Schiff base (4) has been explored as a highly selective and sensitive fluoride ion receptor. Fluoride-induced deprotonation results in a charge transfer (CT) transition red shifted with a fluorescence 'turn-on'. Anion selectivity can be tuned by the electron push-pull property of substituents at the phenyl para-position. Selectivity for F(-) is attributed to the suitable acidity of -NH2. PMID:23875184

Kaloo, Masood Ayoub; Sankar, Jeyaraman

2013-07-19

277

Novel Manganese(III) Complexes with the Schiff Base N,N??(1,2?Phenylene)?bis(3?Hydroxysalicylidenimine)  

Microsoft Academic Search

Four novel manganese(III) complexes have been prepared using the tetradentate ONNO symmetrical Schiff base N,N??(1,2?phenylene)?bis(3?hydroxysalicylidenimine) H4L and employing different manganese(II) and manganese(III) starting salts (chloride, acetate, acetylacetonate and perchlorate). These complexes were thoroughly characterised by elemental analysis, ES mass spectrometry, infrared and paramagnetic H NMR spectroscopies, magnetic susceptibility measurements and molar conductivities. Electrochemical studies by cyclic and normal pulse voltammetry

M. Isabel Fernández; M. Maneiro; R. Pedrido; M. J. Romero

2006-01-01

278

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

PubMed

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

Mehta-D'souza, Padmaja

2012-01-01

279

Synthesis, spectroscopic, electrochemical, DNA binding and photocleavage studies on coordination compounds of bis(4-aminophenyl)methane based novel Schiff bases  

Microsoft Academic Search

Two novel Schiff bases, 4,4?-methylenedianilidene-bis(3-methoxy-4-hydroxy-benzaldehyde) (L1) and 4,4?-methylenedianilidene-bis(3,4-dimethoxybenzaldehyde) (L2), have been prepared by condensing 4,4?-methylenedianiline (MDA) with vanillin and 3,4-dimethoxybenzaldehyde (DMB) respectively\\u000a in ethanolic medium. Metal complexes of the above Schiff bases are prepared from salts of Cu(II), Zn(II), Co(II) and VO(IV).\\u000a They are characterized by elemental analysis, molar conductivity, magnetic moment measurements, IR, 1H NMR, UV-Vis., FAB Mass, and

N. Raman; A. Selvan

2011-01-01

280

New tetradentate Schiff bases of 2,2-dimethyl-1,3-diaminopropane and acetylacetone derivatives and their vanadyl complexes.  

PubMed

A series of new VO(IV) complexes with two new tetradentate Schiff base of 4,4'-(2,2-dimethylpropane-1,3-diyl)-bis(azan-1-yl-1-yldene)dipent-2-en-2-ol) [H(2)L(1)] and 3,3'-(2,2-dimethylpropane-1,3-diyl)azan-1-yl-1-ylidene)-bis(1-phenylbut-1-en-1-ol) [H(2)L(2)] (which have been derived from 2,2-dimethyl-1,3-diaminopropan, and diketones of acetylacetone and benzoylacetone) were synthesized and characterized by (1)H NMR, (13)C NMR, FT-IR, mass and UV-Vis spectrophotometry. The electrochemical properties of the vanadyl complexes were investigated by means of cyclic voltammetry. The oxidation potentials are increased by increasing the electron-withdrawing properties of functional groups of the Schiff base ligands according to the trend of MeSchiff base characteristics. The thermal decomposition of the studied reactions was first order. The kinetic parameters for the decomposition steps in vanadyl complexes thermograms have been calculated. PMID:22885931

Mohammadi, Khosro; Rastegari, Mina

2012-07-22

281

Kinetics and thermodynamics of irreversible inhibition of matrix metalloproteinase 2 by a Co(III) Schiff base complex  

PubMed Central

Cobalt(III) Schiff base complexes have been used as potent inhibitors of protein function through the coordination to histidine residues essential for activity. The kinetics and thermodynamics of the binding mechanism of Co(acacen)(NH3)2Cl [Co(acacen); where H2acacen is bis(acetylacetone)ethylenediimine] enzyme inhibition has been examined through the inactivation of matrix metalloproteinase 2 (MMP-2) protease activity. Co(acacen) is an irreversible inhibitor that exhibits time- and concentration-dependent inactivation of MMP-2. Co(acacen) inhibition of MMP-2 is temperature-dependent, with the inactivation increasing with temperature. Examination of the formation of the transition state for the MMP-2/Co(acacen) complex was determined to have a positive entropy component indicative of greater disorder in the MMP-2/Co(acacen) complex than in the reactants. With further insight into the mechanism of Co(acacen) complexes, Co(III) Schiff base complex protein inactivators can be designed to include features regulating activity and protein specificity. This approach is widely applicable to protein targets that have been identified to have clinical significance, including matrix metalloproteinases. The mechanistic information elucidated here further emphasizes the versatility and utility of Co(III) Schiff base complexes as customizable protein inhibitors.

Harney, Allison S.; Sole, Laura B.

2012-01-01

282

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

SciTech Connect

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.

Li Wei; Li Zongwei [Department of Chemistry, Nankai University, 94 Weijing Road, Tianjin 300071 (China); Li Licun [Department of Chemistry, Nankai University, 94 Weijing Road, Tianjin 300071 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002 (China)], E-mail: llicun@nankai.edu.cn; Liao Daizheng; Jiang Zonghui [Department of Chemistry, Nankai University, 94 Weijing Road, Tianjin 300071 (China)

2007-10-15

283

Spectral properties of protonated Schiff base porphyrins and chlorins. INDO-CI calculations and resonance raman studies  

SciTech Connect

INDO-CI calculations successfully reproduce the striking changes in optical spectra that occur upon protonation of mono- and disubstituted porphyrin, chlorin, and bacteriochlorin Schiff base complexes. They ascribe the changes to Schiff base C=N ..pi..* orbitals which drop in energy upon protonation and mix with and perturb the ..pi..* orbitals of the macrocycle, a result consistent with resonance Raman data. The perturbation is predicted to affect not only transition energies and intensities but also dipole moment directions. The symmetry of the porphyrin and the substitution site of the chlorin are shown to play an important role, especially in governing whether the lowest energy transition will red shift or blue shift. Blue shifts are calculated for protonation of ketimine and enamine isomers of pyrochlorophyll a (PChl). Comparison with reported optical spectra suggests that PChl a Schiff base may undergo isomerization upon protonation. Resonance Raman data on CHO, CHNR, CHNHR/sup +/, and pyrrolidine adducts of chlorin demonstrate the isolation of the peripheral C=O and C=N groups from the macrocycle ..pi.. system intramolecular hydrogen bonding, and selective enhancement of v/sub C=N/ for those species with a split Soret band. V/sub C=N/ is observed with 488.0-nm excitation into the lower-energy Soret and absent for 406.7-nm excitation into the higher-energy Soret, a result predicted by the calculations. 44 references, 10 figures, 2 tables.

Hanson, L.K.; Chang, C.K.; Ward, B.; Callahan, P.M.; Babcock, G.T.; Head, J.D.

1984-07-11

284

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

PubMed

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, (1)H 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 CH(3)CN-DMSO (9:1, v/v). Results with imine 1 showed that Fe(3+), Cu(2+), Zn(2+), Cd(2+), Mn(2+), Zr(4+), Hg(2+), Cr(2+), Pb(2+), Sn(2+), Bi(2+), Al(3+), Ce(3+), La(3+), Sm(3+), Gd(3+), Nd(3+), Eu(3+) and Dy(3+) 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 (Zr(4+), Sn(2+), Al(3+) and Zn(2+)) and strong quenching (Fe(3+)). The fluorescence enhancement mechanism of 1 and 2 for metal ions is based on: (i) CN isomerization; (ii) chelation-enhanced fluorescence (CHEF) effect; and (iii) excited-state intra/intermolecular proton transfer (ESPT). PMID:22387686

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

2012-01-28

285

Spectroscopic and electrochemical studies of hetero-bimetallic copper complexes with Schiff's base ligand.  

PubMed

Using Schiff's base ligand, several Cu(II) based bimetallic complexes such as Cu-Cu, Cu-Co, Cu-Ni, Cu-Zn, Cu-Mn have been prepared in a stepwise procedure. The structures of these complexes and the ligand have been proposed on the basis of FAB mass, elemental analysis, UV-vis, IR, electron paramagnetic resonance (EPR) and CV studies. EPR parameters, obtained through complete simulation, suggest that the formation of bimetallic complexes forces the Cu(II) centre to increase the flexibility in comparison with the monometallic Cu(II) complex. However, the nature of the second metal ion in the bimetallic complex effects the distortion around the first metal ion. The reduction of the complexes from Cu(II) to Cu(I) involves a large geometrical change and is found to be irreversible. A large positive shift is seen in the cathodic process, which can be ascribed to increased distortion due to bimetallic coordination. These complexes have potential usage in DNA studies. PMID:16563852

Deepalatha, S; Sambasiva Rao, P; Venkatesan, R

2006-03-23

286

Schiff base switch II precedes the retinal thermal isomerization in the photocycle of bacteriorhodopsin.  

PubMed

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

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

2013-07-29

287

Some bivalent metal complexes of Schiff bases containing N and S donor atoms.  

PubMed

Schiff bases have been synthesized by the reaction of p-nitrobenzaldehyde, o-nitrobenzaldehyde and p-toluyaldehyde with 4-amino-5-mercapto-1,2,4-triazole. The ligands react with Co(II), Ni(II) and Zn(II) metals to yield (1:1) and (1:2) [metal:ligand] complexes. Elemental analyses, IR, 1H NMR, electronic spectral data, magnetic susceptibility measurements, molar conductivity measurements and thermal studies have investigated the structure of the ligands and their metal complexes. The electronic spectral data suggests octahedral geometry for Co(II), Ni(II) and Zn(II). The antibacterial activities of the ligands and their metal complexes have been screened in vitro against three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Pseudomonas aeruginosa) organisms. The coordination of the metal ion had a pronounced effect on the microbial activities of the ligands and the metal complexes have higher antimicrobial effect than the free ligands. PMID:17252949

Singh, Kiran; Singh, D P; Barwa, Manjeet Singh; Tyagi, Parikshit; Mirza, Yasmin

2006-12-01

288

Synthesis and biological evaluation of 3-thiazolocoumarinyl Schiff-base derivatives as cholinesterase inhibitors.  

PubMed

On the basis of the observed biological activity of the coumarins, a new set of 3-thiazolocoumarinyl Schiff-base derivatives with chlorine, hydroxy and methoxy functional group substitutions were designed and synthesized. These compounds were tested against acetylcholinesterase from Electrophorus electricus and butyrylcholinesterase from horse serum and their structure-activity relationship was established. Studies revealed them as the potential inhibitors of cholinesterase (acetylcholinesterase and butyrylcholinesterase). The 3f was found to be most potent against acetylcholinesterase with K(i) value of 1.05 ± 0.3 ?M and 3l showed excellent inhibitory action against butyrylcholinesterase with K(i) value of 0.041 ± 0.002 ?M. The synthesized compounds were also docked into the active sites of the homology models of acetylcholinesterase and butyrylcholinesterase to predict the binding modes of these compounds. It was predicted that most of the compounds have similar binding modes with reasonable binding affinities. Our docking studies have also shown that these synthesized compounds have better interaction patterns with butyrylcholinesterase over acetylcholinesterase. The main objective of the study was to develop new potent and selective compounds, which might be further optimized to prevent the progression of the Alzheimer's disease and could provide symptomatic treatment. PMID:22726458

Raza, Rabia; Saeed, Aamer; Arif, Mubeen; Mahmood, Shamsul; Muddassar, Muhammad; Raza, Ahsan; Iqbal, Jamshed

2012-07-23

289

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

SciTech Connect

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.

Bozell, J.J.; Hames, B.R. [National Renewable Energy Lab., Golden, CO (United States); Dimmel, D.R. [Institute of Paper Science and Technology, Atlanta, GA (United States)

1995-04-21

290

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

PubMed Central

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.

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

2011-01-01

291

Tetradentate Schiff base ligands and their complexes: synthesis, structural characterization, thermal, electrochemical and alkane oxidation.  

PubMed

Three Schiff base ligands (H(2)L(1)-H(2)L(3)) with N(2)O(2) donor sites were synthesized by condensation of 1,5-diaminonapthalene with benzaldehyde derivatives. A series of Cu(II), Co(II), Ni(II), Mn(II) and Cr(III) complexes were prepared and characterized by spectroscopic and analytical methods. Thermal, electrochemical and alkane oxidation reactions of the ligands and their metal complexes were investigated. Extensive application of 1D ((1)H, (13)C NMR) and 2D (COSY, HETCOR, HMBC and TOSCY) NMR techniques were used to characterize the structures of the ligands and establish the (1)H and (13)C resonance assignments of the three ligands. Ligands H(2)L(1) and H(2)L(3) were obtained as single crystals from THF solution and characterized by X-ray diffraction. Both molecules are centrosymmetric and asymmetric unit contains one half of the molecule. Catalytic alkane oxidation reactions with the transition metal complexes investigated using cyclohexane and cyclooctane as substrates. The Cu(II) and Cr(III) complexes showed good catalytic activity in the oxidation of cyclohexane and cyclooctane to desired oxidized products. Electrochemical and thermal properties of the compounds were also investigated. PMID:22571942

Ceyhan, Gökhan; Köse, Muhammet; McKee, Vickie; Uru?, Serhan; Gölcü, Ay?egül; Tümer, Mehmet

2012-04-21

292

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

293

Effect of acids on the infrared spectra of the Schiff base of trans-retinal  

SciTech Connect

trans-Retinylidene-tert-butylamine was put into contact with a series of acids (HCl, HBr, and HI and six carboxylic acids, trichloro-, dichloro-, monochloro-, and monobromoacetic acids, and 3-chloropropionic and propionic acids) whose pK/sub a/ values vary from 0.66 to 4.87. It can be inferred from the Fourier-transform infrared spectra that in order to obtain complete protonation of the Schiff base in chloroform solution an acid having a pK/sub a/ value of at least 2 is needed. With a pK/sub a/ value of about 4, similar to that of aspartic or glutamic acid, the estimated degree of protonation is about 65%. This shows that a mechanism is required to bring about 100% or nearly 100% protonation in rhodopsins. The intensification of the C double bond C bands upon protonation shows that the positive charge is delocalized along the conjugated chain. The N/sup +/H stretching region of the spectrum could be studied to advantage but the N/sup +/H in-plane bending bands could not be identified.

Lussier, L.S.; Sandorfy, C.; Le-Thanh, H.; Vocelle, D.

1987-04-23

294

Stereoselective polymerization of rac-lactide using a monoethylaluminum Schiff base complex.  

PubMed

A monoethylaluminum Schiff base complex (2) with formula LAlEt (L = N,N'-(2,2-dimethylpropylene)bis(3,5-di-tert-butylsalicylideneimine) was synthesized and employed for the stereoselective ring-opening polymerization of rac-lactide (rac-LA). The complex 2 was characterized by nuclear magnetic resonance, crystal structure, and elemental analysis. It contains a five-coordinate aluminum atom with distorted trigonal bipyramidal geometry in the solid state. In the presence of 2-propanol, 2 showed high stereoselectivity for the polymerization of rac-LA. The polymerization yielded crystalline poly(rac-LA) with a high melting temperature (193-201 degrees C). NMR, differential scanning calorimetry, and wide-angle X-ray diffraction indicated that the poly(rac-LA) was highly isotactic, and a stereocomplex was formed between poly-l- and poly-d-lactide block sequences. By the analysis of electrospray-ionization mass spectrometry and (1)H NMR, the polymer was demonstrated to be endcapped in both terminals with an isopropyl ester and a hydroxy group, respectively. The polymerization was of first order in rac-LA concentration. The relationship between the rac-LA conversion and molecular weights of the polymer was linear so that the polymerization could be well controlled. PMID:15132688

Tang, Zhaohui; Chen, Xuesi; Pang, Xuan; Yang, Yongkun; Zhang, Xuefei; Jing, Xiabin

295

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

PubMed

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

Yildirim, Mehmet; Kaya, Ismet

2010-03-06

296

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

SciTech Connect

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.

Malhado, Joao Pedro [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, 05314-970 Sao Paulo, SP (Brazil); Hynes, James T. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215 (United States); Chemistry Department, Ecole Normale Superieure, UMR ENS-CNRS-UPMC 8640, 24 rue Lhomond, 75005 Paris (France)

2012-12-14

297

QM study and conformational analysis of an isatin Schiff base as a potential cytotoxic agent.  

PubMed

Isatin is an important compound from the biological aspect of view. It is an endogenous substance and moreover; various pharmacological activities have been reported for isatin and its derivatives. In-vitro cytotoxic effects of the prepared isatin Schiff bases toward HeLa, LS180 and Raji human cancer cell lines has been reported in our previous work. 3-(2-(4-nitrophenyl)hydrazono) indolin-2-one was found to be the most potent one among the studied compounds (IC(30)?=12.2 and 21.8 ?M in HeLa and LS-180 cell lines, respectively). Obtained biological data could be well interpreted using docking binding energies toward vascular endothelial growth factor receptor (VEGFR-2); a key anticancer target being biologically investigated against various isatin derivatives. In the present work, quantum mechanical (QM) method including functional B3LYP in association with split valence basis set using polarization functions (Def2-SVP) was used to estimate individual ligand-residue interaction energies for the docked 3-(2-(4-nitrophenyl)hydrazono) indolin-2-one into VEGFR-2 active site. Results were further interpreted via calculated polarization effects induced by individual amino acids of the receptor active site. A fairly good correlation could be found between polarization effects and estimated binding energies (R(2)?=0.7227). Conformational analysis revealed that 3-(2-(4-nitrophenyl) hydrazono) indolin-2-one might not necessarily interact with the VEGFR-2 active site in its minimum energy conformation. PMID:23053004

Miri, Ramin; Razzaghi-asl, Nima; Mohammadi, Mohammad K

2012-09-29

298

Excited-state dynamics of protonated retinal Schiff base in solution  

SciTech Connect

The dynamics of all-trans and 13-cis retinal protonated Schiff base (RPSB) were studied in different solvents by means of picosecond transient spectroscopy. The decay time of the excited state absorption was found to be wavelength dependent due to the contribution of the faster decay of stimulated emission. The stimulated emission has a lifetime of a 2.5-4 ps while the excited state absorption decay is biexponential with lifetimes of 2.5-4 and 10-12 ps. The fluorescence quantum yield is strongly temperature dependent but viscosity has a small effect on both excited-state lifetime and fluorescence quantum yield. This leads to the conclusion that there is a {approx}600 cm{sup -1} barrier in the excited-state which results from intramolecular electronic factors and not from the solvent viscosity. The comparison of these results with those for the retinal in rhodopsin and bacteriorhodopsin is discussed in terms of the protein catalysis for the retinal photoisomerization. 31 refs., 8 figs., 2 tabs.

Logunov, S.L.; Li, S.; El-Sayed, M.A. [Georgia Inst. of Technology, Atlanta, GA (United States)

1996-11-21

299

Charge transfer complexes of adenosine-5'-monophosphate and cytidine-5'-monophosphate with water-soluble cobalt(II) Schiff base complexes in aqueous solution.  

PubMed

Water-soluble cobalt(II) tetradentate Schiff base complexes have been shown to form charge transfer (CT) complexes with a series of nucleoside monophosphates including adenosine-5'-monophosphate (AMP) and cytidine-5'-monophosphate (CMP). The investigated water-soluble cobalt(II) Schiff base complexes are (i) disodium[{bis(5-sulfo-salicylaldehyde)-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-salophen)] (1); (ii) disodium[{bis(5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na2[Co(SO3-sal-4,5-dmophen)] (2) and (iii) disodium[{bis(4-methoxy-5-sulfo-salicylaldehyde)-4,5-dimethyl-o-phenylenediiminato}cobalt(II)], Na(2)[Co(SO3-4-meosal-4,5-dmophen)] (3). The formation constant and thermodynamic parameters for charge transfer complex formation of water-soluble cobalt(II) Schiff base complexes with nucleoside monophosphates were determined spectrophotometrically in aqueous solution at constant ionic strength (I = 0.2 mol dm(-3) KNO3) under physiological condition (pH 7.0) and at various temperatures between 288 and 308 K. The stoichiometry has been found to be 1:1 (water-soluble cobalt(II) Schiff base complex: nucleoside monophosphate) in each case. Our spectroscopic and thermodynamic results show that the interaction of water-soluble cobalt(II) Schiff base complexes with the investigated nucleoside monophosphates occurs mainly through the phosphate group. The trend of the interaction according to the cobalt(II) Schiff base complexes due to electronic and steric factors is as follows: Na2[Co(SO3-salophen)] > Na2[Co(SO3-sal-4,5-dmophen)] > Na2[Co(SO3-4-meosal-4,5-dmophen)]. Also the trend of the interaction of a given cobalt(II) Schiff base complex according to the nucleoside monophosphate is as follows: CMP > AMP. PMID:15950536

Boghaei, Davar M; Gharagozlou, Mehrnaz

2005-06-13

300

Synthesis, characterization and biological activity of ferrocene-based Schiff base ligands and their metal (II) complexes  

NASA Astrophysics Data System (ADS)

Metal (II) complexes derived from S-benzyl-N-(1-ferrocenyl-3-(4-methylbenzene)acrylketone) dithiocarbazate; HL1, S-benzyl-N-(1-ferrocenyl-3-(4-chlorobenzene)acrylketone)dithiocarbazate; HL2, all the compounds were characterized using various spectroscopic techniques. The molar conductance data revealed that the chelates were non-electrolytes. IR spectra showed that the Schiff bases were coordinated to the metal ions in a bidentate manner with N, S donor sites. The ligands and their metal complexes have been screened for in vitro antibacterial, antifungal properties. The result of these studies have revealed that zinc (II) complexes 6 and 13 of both the ligands and copper (II) complexes 9 of the HL2 were observed to be the most active against all bacterial strains, antifungal activity was overall enhanced after complexation of the ligands.

Liu, Yu-Ting; Lian, Gui-Dan; Yin, Da-Wei; Su, Bao-Jun

301

Syntheses and characterization of a chelating resin containing ONNO donor quadridentate Schiff base and its coordination complexes with copper(II), nickel(II), cobalt(II), iron(III), zinc(II), cadmium(II), molybdenum(VI) and uranium(VI) 1 ONNO indicates donor sites of the quadridentate Schiff base. 1 , 2 Presented at the National Seminar on Reactive and Functional Polymers held at Gujarat University, Ahmedabad, Gujarat, India in March, 1996. 2  

Microsoft Academic Search

A new mixed Schiff base N,N?-ethylenemono(3-carboxysalicylideneimine)mono(salicylideneimine) has been synthesized by the condensation of equimolar quantities of ethylenediamine, salicylaldehyde and 3-formylsalicylic acid. A polymer supported Schiff base (PS–CH2–LH2) has been synthesized by the reaction of chloromethylated polystyrene (containing 3.9 mmol of chlorine per g of resin and 2% cross-linked with divinylbenzene) and the Schiff base N,N?-ethylenemono(3-carboxysalicylideneimine)mono(salicylideneimine). The polymer-anchored Schiff base reacts

A. Syamal; M. M. Singh; D. Kumar

1999-01-01

302

Synthesis and electrochemical studies of heterobinuclear complexes containing copper and molybdenum nitrosyl groups linked by Schiff base ligands  

Microsoft Academic Search

The reaction of [MoCl(NO)Tp\\u000a * = tris(3,5-dimethylpyrazolylborate] with copper Schiff base complexes derived by condensation of one mole each of 2,5-dihydroxybenzaldehyde\\u000a and salicylaldehyde with ?,? diamines [NH2(CH2)\\u000a n\\u000a NH2, n = 2–4] yields heterobinuclear complexes with two potential redox centres. I.r., electronic and e.s.r. spectroscopic properties\\u000a of these complexes are described. Cyclic voltammetric data of the base complexes in DMSO

Samwel T. Lutta

2000-01-01

303

Oxorhenium(V) complexes containing tridentate Schiff-base and monothiol coligands  

PubMed Central

The reaction of [n-(C4H9)4N][ReOBr4(OPPh3)] with the tridentate Schiff-base [HOC6H4C(H)NC6H4SH] allows for the isolation of [ReOBr{?3-(OC6H4C(H)NC6H4S)}] (1). The reaction of [n-(C4H9)4N][ReOBr4(OPPh3)] with [HOC6H4C(H)NC6H4SH] and the appropriate benzenethiol (C6H4X-4-SH) where X=H, Br, Cl, F, and OCH3 in methanol–acetonitrile treated with triethylamine has led to the isolation of a series of rhenium complexes of the type [ReO{?3-(OC6H4C(H)NC6H4S)} (?1-C6H4X-4-S)] (X=H (2), Br (3), Cl (4), F (5), and OCH3 (6)). Likewise, under similar reaction conditions, the use of benzylmercaptan ligands of the type (C6H4X-4-CH2SH) where X=H, Cl, F, and OCH3 has led to the isolation of a series of rhenium complexes of the type [ReO{?3-(OC6H4C(H)NC6H4S)} (?1-C6H4X-4-CH2S)] (X=H (7), Cl (8), F (9), and OCH3 (10)). The incorporation of the appropriate amine functionality into the substituent R of the monodentate ligand allows for the isolation of a cationic oxorhenium(V) species, namely, [ReO{?3-(OC6H4C(H)NC6H4S)} (?1-C5H4NH-2-S)][Br] (11).

Femia, Frank J.; Chen, Xiaoyuan; Babich, John W.; Zubieta, Jon

2010-01-01

304

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

SciTech Connect

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.

Ortiz-Sanchez, Juan Manuel; Gelabert, Ricard; Moreno, Miquel; Lluch, Jose M. [Departament de Quimica, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)

2008-12-07

305

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)

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.

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

2011-09-01

306

Synthetic, structural and biological studies of organosilicon(IV) complexes of Schiff bases derived from pyrrole-2-carboxaldehyde  

Microsoft Academic Search

Some new organotin(IV) complexes having general formulae R2MCl(L) and R2M(L)2 were synthesized by the reactions of Me2MCl2 with Schiff bases (5-Mercapto-4-(pyrrolcarboxalideneamino)-s-triazole, 5-Mercapto-3-methyl-4-(2-pyrrol- carboxalideneamino)-s-triazole, 3-Ethyl-5-mercapto-4-(2-pyrrolcarboxalideneamino)-s-triazole) in 1:1 and 1:2 molar ratios. All of the compounds were characterized by elemental analysis, molar conductance, IR, UV, 1 H, 13 C and 119 Sn NMR spectral studies. 1 H NMR spectral data suggest the

Singh Kiran; Pal Dharam

2010-01-01

307

Complexes of Co, Ni, Cu, Zn and Cd with Some Bi-and Tridentate Schiff Base Ligands  

Microsoft Academic Search

A series of new complexes of bivalent ions of Co, Ni, Cu, Zn and Cd with Schiff bases 4-[p-N,N-dimethyl-aminobenzylideneamino]-5-mercapto-3-trifluoromethyl-s-triazole (DBMTT) and 4-[2-hydroxynaphthalideneamino]-5-mercapto-3-trifluoromethyl-s-triazole (HNMTT) derived from p-N,N-dimethylaminobenzaldehyde, 2-hydroxy-1-naphthaldehyde and 4-amino-5-mercapto-3-trifluoromethyl-s-triazole, have been synthesized and characterized by elemental analyses, magnetic susceptibility measurements, infrared and electronic spectral data. The ligands have been characterized on the basis of IR and H NMR spectra. The

S. N. Dubey; Beena Kaushik

1987-01-01

308

Coordination chemistry and biological activity of two tridentate ONS and NNS Schiff bases derived from S-benzyldithiocarbazate  

Microsoft Academic Search

Two tridentate Schiff bases having ONS and NNS donor sequences were prepared by condensing S-benzyldithiocarbazate (NH2NHCSSCH2Ph) (SBDTC) with pyridine-2-carboxaldehyde and salicylaldehyde, respectively. Complexes of these ligands with NiII, ZnII, CrIII, CoII, CuII, and SnII were studied and characterized by elemental analyses and various physico-chemical techniques. NiII, CuII, ZnII and SnII complexes were four-coordinate while the CrIII, SrIII and CoIII complexes

M. Tofazzal H. Tarafder; Manaf A. Ali; N. Saravanan; Wong Y. Weng; Saravana Kumar; N. Umar-Tsafe; Karen A. Crouse

2000-01-01

309

Schiff bases attached L-glutamine and L-asparagine: First investigation on antimutagenic and antimicrobial analyses.  

PubMed

This study was conducted to evaluate the antimutagenic and antimicrobial activities of Schiff bases attached L-glutamine and L-asparagine. Antibacterial activities of the compounds against S. aureus, Sh. dys. typ 7, L. monocytogenes 4b, E. coli, S. typhi H, S. epidermis, Br. abortus, M. luteus, B. cereus, P. putida, and antifungal activity against Candida albicans were studied. These compounds were investigated for antimutagenic properties against Aflatoxin B? (AFB?) using micronuclei (MN) assay in human lymphocyte cell culture in vitro. The protective role of these compounds against AFB?-induced MN is probably related to its doses. PMID:23687951

Sakiyan, Iffet; Anar, Mustafa; O?ütcü, Hatice; Agar, Guleray; Sar?, Nur?en

2013-05-20

310

Chemical mechanism of dioxygen activation by manganese(III) Schiff base compound in the presence of aliphatic aldehydes  

Microsoft Academic Search

The manganese(III) complexes with tetradentate Schiff base [H2(L)] derived from salicylaldehyde and 2-amino-1-benzylamine [abbreviated as H2(salabza)], ethylenedimaine and 2-hydroxybenzophenone [H2(7-Phe-salen)], ethylenediamine and 2-hydroxyacetophenone [H2(7-Me-salen)] showed much higher activity for degradation of tetraphenylcyclopentadienone(TCPN) the singlet oxygen (1?g) scavenger, in the presence of cyclohexanecarboxaldehyde than those of the compounds with H2(salen) and H2(salphen), which are derived from salicyaldehyde and ethylenediamine, and o-phenylenediamine,

Miyuki Suzuki; Takashi Ishikawa; Akihiko Harada; Shigeru Ohba; Masatomi Sakamoto; Yuzo Nishida

1997-01-01

311

Synthesis, Structure, and Properties of a Tetranuclear Cubane-like Nickel(II) Complex with Tridentate Schiff Base Ligand  

Microsoft Academic Search

A new tetranuclear cubane-like complex, [Ni4(L)4(EtOH)4]·(H2O), has been synthesized from the reaction of simple metal salt with tridentate Schiff base ligand derived from salicylidene-2-aminobenzoic alcohol (H2L), and its crystal structure, spectroscopic and electrochemical properties have been studied. The complex possessed a [Ni4O4] core comprising a distorted cubane arrangement, of which four nickel(II) ions were bridged by ?3-alkoxo group. Each nickel(II)

Huiyan Liu; Haiying Wang; Dezhong Niu; Zaisheng Lu

2005-01-01

312

Structural, spectroscopic, and biological aspects of S?N donor Schiff-base ligands and their chromium(III) complexes  

Microsoft Academic Search

New chromium(III) complexes are synthesized by classical thermal and microwave (MW)-irradiated techniques. The Schiff bases 2-acetylfuran-S-benzyldithiocarbazate (LH), 2-acetylthiophene-S-benzyldithiocarbazate (LH), 2-acetylpyridine-S-benzyldithiocarbazate (LH), and 2-acetylnaphthalene-S-benzyldithiocarbazate (LH) were prepared by condensation of -S-benzyldithiocarbazate in ethanol with the respective ketones by using MW as well as conventional methods. The chromium(III) complexes have been prepared by mixing CrCl3 · 6H2O in 1 : 1 and

Sumit Shrivastava; Nighat Fahmi; D. Singh; R. V. Singh

2010-01-01

313

Minimum energy paths in the excited and ground states of short protonated Schiff bases and of the analogous polyenes  

Microsoft Academic Search

A theoretical study of the minimum energy paths (MEP) for the first excited state S1 and for the ground state S0 of two short-chain protonated Schiff bases (the protonated s-cis 1-iminium-2-propene H2C=CH-CH=NH2 + and the protonated tZt 1-iminium-2,4-pentadiene H2C=CH-CH=CH-CH=NH2 +) and of the two analogous polyenes (s-cis butadiene H2C=CH-CH=CH2 and tZt hexatriene H2C=CH- CH=CH-CH=CH2) is reported. The geometries have been

Marco Garavelli; Fernando Bernardi; Paolo Celani; Michael A. Robb; Massimo Olivucci

1998-01-01

314

A novel centrosymmetric dinuclear cadmium(II) Schiff base complex with unusual bridging carboxylate: Synthesis, crystal structure and luminescence properties  

Microsoft Academic Search

A novel centrosymmetric dinuclear Cd(II) complex [CdL (CH3COO)]2 (1) has been synthesized by the reaction of Cd(CH3COO)2·2H2O with a Schiff base ligand HL [HL=(E)-2-((pyridin-2-yl)methyleneamino)benzoic acid]. Title complex has been systematically characterized by elemental analysis, FT-IR, and thermal studies. Single crystal X-ray structural analysis reveals that Cd(II) centers in 1 adopt distorted monocapped octahedral geometry and held together by rare doubly

Shyamapada Shit; Joy Chakraborty; Brajagopal Samanta; Guillaume Pilet; Samiran Mitra

2009-01-01

315

Approaches to the aqueous chemistry of chromium (IV) and chromium (V) in macrocyclic and Schiff base complexes  

Microsoft Academic Search

The stabilization of chromium(IV) and chromium(V) in aqueous systems has now been made through designed alterations in Franck-Condon\\u000a barriers for the interconversion of various oxidation states of chromium. Equatorially coordinated macrocyclic and Schiff\\u000a base ligands influence the reorganizational barriers for the conversion of Cr(III)-Cr(IV)-Cr(V)-Cr(VI) couples such that Cr(IV)\\u000a and Cr(V) transients of sufficiently long life time can be generated. A

Balachandran Unni Nair; M. Kanthimathi; K. Chandra Raj; T. Ramasami

1994-01-01

316

Oxidative Polymerization of N 2 0 2 Type Schiff Base Monomer and Its Metal Complexes: Synthesis and Thermal, Optical and Electrochemical Properties  

Microsoft Academic Search

\\u000a Abstract  This article describes the synthesis and some properties of a new phenol-based Schiff base oligomer and its metal complexes.\\u000a First, Schiff base monomer, 2,3-bis[(2-hydroxy-naphtyl)methylene]diaminopyridine (HNMDAP) was synthesized by condensation\\u000a of 2-hydroxy-1-naphtaldehyde with 2,3-diaminopyridine. Then, HNMDAP was oxidized to give its corresponding oligomer (OHNMDAP)\\u000a in the presence of the oxidants such as H2O2, NaOCl and air in alkaline medium. Finally, OHNMDAP

Ali Bilici; ?smet Kaya; Mehmet Saçak

2010-01-01

317

Synthesis and structural characterization of two five coordinate aluminum alkyl and bis(trimethylsilyl)amino complexes bearing acyclic tetradentate Schiff bases  

Microsoft Academic Search

Two acyclic Schiff-base ligands, bis-5,5?-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-one and bis-5,5?-(1,3-ethanediyldiimino)-2,2-dimethyl-4-hexene-3-one, were used to complex homoleptic triethylaluminum and tris[bis(trimethylsilyl)amino]aluminum, respectively. The acid–base reactions proceeded in excellent yields with elimination of ethane or bis(trimethylsilyl)amine during in situ deprotonation of the protio Schiff-base. The colorless aluminum complexes crystallized from n-pentane and were characterized by standard methods including single crystal X-ray diffraction. Polymerization of racemic lactide, with

C. R. Wade; B. J. Lamprecht; V. W. Day; J. A. Belot

2007-01-01

318

Cobalt, nickel, copper and zinc complexes with 1,3-diphenyl-1H-pyrazole-4-carboxaldehyde Schiff bases: antimicrobial, spectroscopic, thermal and fluorescence studies.  

PubMed

Two new Schiff bases of 1,3-diphenyl-1H-pyrazole-4-carboxaldehyde and 4-amino-5-mercapto-3-methyl/H-1,2,4-triazole [HL(1-2)] and their Cobalt, Nickel, Copper and Zinc complexes have been synthesized and characterized by elemental analyses, spectral (UV-vis, IR, (1)H NMR, Fluorescence) studies, thermal techniques and magnetic measurements. A square planar geometry for Cu(II) and octahedral geometry for Co(II), Ni(II) and Zn(II) complexes have been proposed. In order to evaluate the biological activity of Schiff bases and to assess the role of metal ion on biological activity, the pyrazole Schiff bases and their metal complexes have been studied in vitro antibacterial against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and antifungal against Aspergillus niger, and Aspergillus flavus. In most of the cases higher activity was exhibited upon coordination with metal ions. PMID:22429912

Singh, Kiran; Kumar, Yogender; Puri, Parvesh; Kumar, Mahender; Sharma, Chetan

2012-03-03

319

Evidence for Schiff base formation in the catalytic mechanism of phosphonoacetaldehyde hydrolase  

Microsoft Academic Search

Phosphonoacetaldehyde hydrolase (PAH) catalyzes the hydrolysis of the P-C bond in phosphonoacetaldehyde (PA) to yield P\\/sub i\\/ and acetaldehyde (AA). The enzyme requires MgS and is inactivated by NaBH4 in the presence of PA. The mechanism of PAH may be analogous to the US -ketodecarboxylases in which Mg may activate the substrate for bond cleavage or in which a Schiff

D. B. Olsen; T. W. Hepburn; D. Dunaway-Mariano; P. S. Mariano

1987-01-01

320

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)

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.

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

2013-04-01

321

Synthesis and Characterization of a New Schiff Base and its Metal Complexes Derived from the Mannich Base, N-(1-piperidinobenzyl)acetamide  

Microsoft Academic Search

New neutral Schiff base complexes of Cu(II), Co(II), Ni(II), and Zn(II) derived from 4-aminoantipyrine and N-(1-piperidinobenzyl)acetamide (Mannich base) have been synthesized. The structural features of the complexes have been characterized by microanalytical data, IR, UV-Vis, H NMR, ESR, CV, TGA and powder XRD techniques. Electronic absorption spectra of the complexes indicate an octahedral geometry around the metal ion. The neutral

N. Raman; S. Ravichandran

2005-01-01

322

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

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

323

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

PubMed

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 UO2(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. PMID:21130026

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

2010-06-11

324

Magnetic and catalytic properties of a new copper(II)–Schiff base 2D coordination polymer formed by connected helical chains  

Microsoft Academic Search

A dicyanamide bridged 2D polynuclear complex of copper(II) having molecular formula [Cu2(L)(?1,5-dca)2]n (1) has been synthesized using the Schiff base ligand N,N?-bis(salicylidene)-1,3-diaminopentane, (H2L) and sodium dicyanamide (dca). The complex presents a 2D hexagonal structure formed by 1,5-dca singly bridged helical chains connected through double 1,5-dca bridges. The chelating characteristics of the H2L Schiff base ligand results in the formation of

Dipali Sadhukhan; Aurkie Ray; Ray J. Butcher; Carlos J. Gómez García; Bülent Dede; Samiran Mitra

2011-01-01

325

Electrochemical studies of iron(III) Schiff base complexes—II. Dimeric ?-OXO[Fe III (N 2O 2)] 2O complexes  

Microsoft Academic Search

The electrochemical reduction of ?-oxo bridged FeIII dimers (L)Fe?O?Fe(L), where L is a Schiff base, has been investigated in aprotic solvents by cyclic voltammetry and coulometry with UV-vis spectroscopy. Three complexes deriving from Schiff base ligands with N2O2 environments are described. The reduction of (L)FeIII?O?FeIII(L) occurs at a potential around ?1 V\\/SCE and releases the monomeric FeII(L) complex. A mechanism

F. Soulet; P.-L. Fabre

1995-01-01

326

Spectroscopic characterization and electrochemical studies of ruthenium(II) carbonyl complexes containing bidentate Schiff bases and triphenylphosphine or a nitrogen heterocycle  

Microsoft Academic Search

Reactions of ruthenium(II) carbonyl complexes of the type [RuHCl(CO)(PPh3)2(B)] [B?=?PPh3, pyridine (py), piperidine (pip) or morpholine (mor)] with bidentate Schiff base ligands derived from the condensation of 2-hydroxy-1-naphthaldehyde with aniline, o-, m- or p-toluidine in a 1?:?1 mol ratio in benzene resulted in the formation of complexes formulated as [RuCl(CO)(L)(PPh3)(B)] [L?=?bidentate Schiff base anion, B?=?PPh3, py, pip, mor]. The complexes

Sethuraman Kannan; R. Ramesh

2005-01-01

327

Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: Synthesis, characterization, properties and biological activity  

Microsoft Academic Search

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·nH2O, where M=Cr(III),

Eren Keskioglu; Ayla Balaban Gündüzalp; Servet Çete; Fatma Hamurcu; Birgül Erk

2008-01-01

328

Synthesis and characterization of polystyrene-anchored monobasic bidentate Schiff base and its complexes with bi-, tri-, tetra- and hexavalent metal ions  

Microsoft Academic Search

A new monobasic bidentate ON donor Schiff base PS–LH2 (where PS–LH2 = polystyrene-anchored Schiff base obtained by condensation of chloromethylated polystyrene (containing 1.17 mmol of chlorine per gram of resin cross-linked with 2% divinylbenzene), 2-hydroxy-1-naphaldehyde and 4-aminosalicylic acid has been synthesized. PS–LH2 reacts with metal complexes to form polystyrene-anchored complexes: PS–LHM(CH3Coo) · DMF (where M = Cu, Zn, Cd, UO2),

D. Kumar; A. Syamal; L. K. Sharma

2008-01-01

329

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

PubMed

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

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

2005-05-01

330

Templating Schiff-base lateral macrobicycles: an experimental and theoretical structural study of the intermediates.  

PubMed

In this paper, we report a structural study both in the solid state and in solution of barium complexes with the diamine N,N'-bis(2-aminobenzyl)-4,13-diaza-18-crown-6 (L(2)), that allows us to rationalize the template effect of the metal ion in the synthesis of Schiff-base lateral macrobicycles resulting from the condensation of L(2) with different dicarbonyl compounds. The X-ray crystal structures of [Ba(L(2))(ClO(4))](ClO(4)) (3) [triclinic space group P1 with Z = 2, a = 10.467(2) A, b = 10.4755(2) A, c = 16.9911(3) A, alpha = 85.075(1) degrees, beta = 80.907(1) degrees, and gamma = 61.627(4) degrees ] and [Ba(L(2))(NCS)(H(2)O)](SCN) (4) [monoclinic space group P2(1)/n with Z = 4, a = 9.954(5) A, b = 29.193(5) A, c = 11.313(5) A, and beta = 91.371(5) degrees ] demonstrate that in the solid state the barium(II) ion induces an anti conformation of the receptor in the complexes. Variable temperature (1)H and (13)C NMR data point out that in solution compounds 3 and 4 exist as a mixture of syn and anti isomers. The presence of the syn isomer in solution, independent of the counterion employed (perchlorate or thiocyanate), accounts for the effectiveness of the barium(II) ion as a template agent in the synthesis of the lateral macrobicycles resulting from the condensation of L(2) with different dicarbonyl compounds. Density functional theory calculations (at the B3LYP/LanL2DZ level) for [Ba(L(2))](2+) predict the syn conformation to be more stable both in vacuo and in solution (PCM model). In order to asses which of the two isomers predominates in acetonitrile solution, the (13)C NMR shielding tensors of the two isomers of [Ba(L(2))](2+) were calculated for the in vacuo optimized structures by using the GIAO method, and the results were compared with the experimental ones. According to these analyses, a syn stereochemistry is assigned to the major species in solution. PMID:12844302

Platas-Iglesias, Carlos; Esteban, David; Ojea, Vicente; Avecilla, Fernando; de Blas, Andrés; Rodríguez-Blas, Teresa

2003-07-14

331

Complexes of a porphyrin-like N4-donor Schiff-base macrocycle.  

PubMed

A metal-free 16-membered N4-donor [1 + 1] Schiff-base macrocycle was isolated as HL(Pr)·2acid, by 1?:?1 condensation of diphenylamine-2,2'-dicarboxaldehyde (1), dipropylene triamine and an excess of either acetic or formic acid, or as HL(Pr)·(tosylic acid) when just one equivalent of tosylic acid was employed. Interestingly, the acid-free synthesis employed for the 14-membered analogue HL(Et) failed to generate pure HL(Pr) macrocycle, but nevertheless the crude product obtained was able to be used in subsequent complexation reactions to form five mononuclear complexes: Zn(II)L(Pr)(BF4)·H2O·0.5IPA (where IPA is isopropylalcohol), [Cu(II)L(Pr)](BF4), [Ni(II)L(Pr)](BF4), [Co(II)L(Pr)](BF4)·0.5H2O, [Fe(III)L(Pr)(NCS)2]·1.5H2O. Crystal structure determinations show that, like the HL(Et) analogues, [Ni(II)L(Pr)](BF4) features a square planar N4 coordinated Ni(II) centre and [Fe(III)L(Pr)(NCS)2]·0.15MeOH·0.2H2O features an octahedral N6 coordinated Fe(III) centre (two NCS anions bound axially). In both cases the N4-donor macrocycle is bound equatorially to the metal ion. Cyclic voltammograms of the BF4 complexes were carried out in MeCN vs. 0.01 mol L(-1) AgNO3/Ag and revealed multiple redox processes. The Zn(II) complex exhibits multiple ligand-centered redox processes. Interestingly, [Ni(II)L(Pr)](BF4) has two reversible redox processes, at E(m) = +0.38 (?E = 0.06 V) and -1.7 V (?E = 0.06 V), whereas the previously reported analogue [Ni(II)L(Et)](BF4) had a process at E(pc) = +0.59 V with only a weak return wave. Likewise, [Cu(II)L(Pr)](BF4) has a reversible process, at E(m) = -1.17 V (?E = 0.06 V) plus a process at E(pc) = +0.45 V, whereas previously reported [Cu(II)L(Et)](BF4) only featured irreversible processes, with the oxidation occurring at E(pc) = +0.50 V. PMID:23400271

Wilson, Rajni K; Brooker, Sally

2013-02-12

332

Potentiometric membrane electrode for salicylate based on an organotin complex with a salicylal Schiff base of amino acid.  

PubMed

A novel salicylate-selective electrode based on an organotin complex with a salicylal Schiff base of amino acid salicylaldehydeaminoacid-di-n-butyl-Sn(IV) [Sn(IV)-SAADB] as ionophore is described, which exhibits high selectivity for salicylate over many other common anions with an anti-Hofmeister selectivity sequence: Sal- > PhCOO- > SCN- > Cl04- > I- > NO3- > NO2- > Br- > Cl- > CH3COO-. The electrode, based on Sn(IV)-SAADB, with a 30.44 wt% PVC, a 65.45 wt% plasticizer (dioctyl phthalate, DOP), a 3.81 wt% ionophore and a 0.3 wt% anionic additive is linear in 6.0 x 10(-6) - 1.0 x 10(-1) mol l(-1) with a detection limit of 2.0 x 10(-6) mol l(-1) and a slope of 62.0 +/- 1.2 mV/decade of salicylate concentration in a phosphate buffer solution of pH 5.5 at 25 degrees C. The influence on the electrode performances by lipophilic charged additives was studied, and the possible response mechanism was investigated by UV spectra. The electrode was applied to medicine analysis and the result obtained has been satisfactory. PMID:15790114

Xu, Lan; Yuan, Ruo; Fu, Ying-Zi; Chai, Ya-Qin

2005-03-01

333

A novel salicylate-selective electrode based on a Sn(IV) complex of salicylal-imino acid Schiff base.  

PubMed

A novel poly(vinyl chloride) membrane electrode with high selectivity toward salicylate (Sal-), based on the use of the salicylal-imino acid Schiff base dibenyl complex of Sn(IV) [Sn(IV)-SIADBen] as ionophore is described. The influence of lipophilic charged additives on the performance of the electrode was studied. The results suggested that Sn(IV)-SIADBen according to a positively-charged carrier mechanism. The influence of several other variables was investigated in order to optimize the potentiometric response and selectivity of the electrode. The electrode based on Sn(IV)-SIADBen, with 30.44 wt% PVC, 64.55 wt% plasticizer [dioctyl phthalate (DOP)], 3.81 wt% ionophore, and 1.2 wt% anionic additive exhibited a linear response for the Sal- ion over the concentration range 1.0x10(-1) to 2.5x10(-6) mol l-1, and displayed an anti-Hofmeister selectivity sequence as follows: salicylate>perchlorate>thiocyanate>benzoate>iodide>nitrate>chloride>nitrite approximately acetate>citrate>sulfate. UV-Visible absorption spectra were used to examine the specific interaction of salicylate with the ionophore. The electrode was applied to clinical medical analysis, and the results obtained were consistent with those obtained by conventional methods. PMID:15668810

Xu, Lan; Yuan, Ruo; Chai, Ya-Qin; Wang, Xiu-Ling

2005-01-25

334

Spectrophotometric study on the binding of two water soluble Schiff base complexes of Mn(III) with ct-DNA.  

PubMed

In this work, binding of two water soluble Schiff base complexes: Bis sodium (5-sulfosalicylaldehyde) o-phenylendiiminato) Manganese (III) acetate (Salophen complex) and Bis sodium (5-sulfosalicylaldehyde) 1, 2 ethylendiiminato) Manganese (III) acetate (Salen complex) with calf thymus (ct) DNA were investigated by using different spectroscopic and electrometric techniques including UV-vis, Circular dichroism (CD) and fluorescence spectroscopy, viscommetry and cyclic voltammetry (CV). Both complexes have shown a hyperchromic and a small bathochromic shift in the visible region spectra. A competitive binding study showed that the enhanced emission intensity of ethidium bromide (EB) in the presence of DNA was quenched by the addition of the two Schiff base complexes indicating that they displace EB from its binding site in DNA. Moreover structural changes in the CD spectra and an increase in the CV spectra with addition of DNA were observed. The results show that both complexes bind to DNA. The binding constants have been calculated using fluorescence data for two complexes also K(b) was calculated with fluorescence Scatchard plot for Salophen. Ultimately, the experimental results show that the dominant interactions are electrostatic while binding mode is surface binding then followed by hydrophobic interactions in grooves in high concentration of complexes. PMID:21365249

Dehkordi, Maryam Nejat; Bordbar, Abdol-Khlegh; Mehrgardi, Masood Ayatolahi; Mirkhani, Valiolah

2011-03-02

335

Synthesis, physical studies and uptake behavior of: Copper(II) and lead(II) by Schiff base chelating resins  

NASA Astrophysics Data System (ADS)

Two new chelating resins possessing multiple functional groups capable of coordinating with several metal ions are reported. The resins were synthesized by condensing Schiff bases derived from 2-aminophenol, 2-hydroxy-5-chloroaniline and terephthaldehyde with formaldehyde in an alkaline medium. The effects of pH and contact time of the Cu 2+ and Pb 2+ in aqueous solutions on the uptake behavior of the resins were studied. The metal ion uptake behavior of the resins was investigated by the batch method. Both the uptake and the selectivity of the resins towards the investigated metal ions were related to the structure of the resins, type of the metal ion and the uptake conditions. The resins showed maximum uptake capacity for Cu 2+ and Pb 2+ at pH 10. Cu 2+ was seen to undergo preferential adsorption in separate and mixture solutions of Cu 2+ and Pb 2+. Kinetic studies for the resins using Langmiur equation were also performed. The Schiff base monomers and their formaldehyde resins were characterized by elemental analyses, FTIR and 1H NMR spectroscopy. The thermal stability of the resins was studied using TGA/DTG analysis.

Othman, Mohammed K.; Al-Qadri, Fatima A.; Al-Yusufy, Fatima A.

2011-05-01

336

Synthesis, characterization and structural determination of some nickel(II) complexes containing imido Schiff bases and substituted phosphine ligands  

NASA Astrophysics Data System (ADS)

Some new tridentate ONN Schiff base complexes of [NiL(PR3)] (where L = Salicylidene2-amino4-nitrobenzene (L1), 5-BrSalicylidene2-amino4-nitrobenzene (L2), 5-NO2Salicylidene2-amino4-nitrobenzene (L3), 5-MeOSalicylidene2-amino4-nitrobenzene (L4) and 3-MeOSalicylidene2-amino4-nitrobenzene (L5), R = Bu and Ph (with L1)) were synthesised and characterized by IR, UV-Vis, 1H NMR spectroscopy and elemental analysis. The geometry of [NiL1(PPh3)] was determined by X-ray crystallography. It indicated that the complex had a planar structure and four coordinates in the solid state. The thermogravimetry (TG) and differential thermoanalysis (DTA) of the synthesized complexes were carried out in the range of 20-600 °C, leading to the decomposition of L1-L3 type in three stages and of L4-L5 and [NiL1(PPh3)] type in four stages. Thermal decomposition of the complexes was closely the dependent upon the nature of the Schiff base ligands and proceeded via the first order kinetics.

Kianfar, Ali Hossein; Ebrahimi, Mostafa

2013-11-01

337

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

PubMed

New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N'-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L¹) and N'-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L²) are reported. Schiff-base ligands L¹ and L² 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?=?L¹ or L²) 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, ¹H, and ¹³C 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

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

2013-08-21

338

Sensitive voltammetric determination of tryptophan using an acetylene black paste electrode modified with a Schiff's base derivative of chitosan.  

PubMed

Chitosan was modified by salicylaldehyde via Schiff's base reaction and the resulting product was modified on the surface of an acetylene black paste electrode (ABPE) by the drop-coating method. In 0.5 mol L(-1) acetate buffer (pH 4.2), a substantial increase in the anodic stripping peak current of tryptophan (Trp) (compared to conventional bare carbon paste electrode (CPE) and bare ABPE) is observed at the Schiff's base chitosan-modified electrode. The parameters influencing voltammetric determination of Trp have been optimized. Under the selected conditions, the linearity between the anodic peak currents and concentrations of Trp demonstrated a wide range of 6.0 × 10(-8) mol L(-1) to 2.0 × 10(-6) mol L(-1), 2.0 × 10(-6) mol L(-1) to 4.0 × 10(-5) mol L(-1) and 4.0 × 10(-5) mol L(-1) to 1.0 × 10(-4) mol L(-1), a low detection limit of 2.0 × 10(-9) mol L(-1) was obtained after a 60 s accumulation. In addition, the developed electrochemical sensor has been successfully applied for the determination of Trp in pharmaceutical and biological samples with satisfactory assay results. PMID:22010111

Deng, Peihong; Fei, Junjie; Feng, Yonglan

2011-10-19

339

Syntheses and structural characterization of rhenium-bis-hydrazinopyrimidine core complexes with thiolate and Schiff base coligands  

Microsoft Academic Search

The reaction of perrhenate with 2-hydrazinopyrimidine in MeOH–HCl yields [ReCl3(?1-NNC4H3N2H)(?2-HNNC4H3N2)] (1). The analogous reaction with Na2MoO4 yields [MoCl3(?1-NNC4H3N2H)(?2-HNNHC4H3N2)] (1a). The reaction of 1 with pyrimidine-2-thiol and triethylamine produces [Re(?1-C4H3N2S)(?2-C4H3N2S)(?1-NNC4H3N2)(?2-HNNC4H3N2)] (2), while reaction of 1 with the Schiff base HSC6H4N?C(H)C6H4OH provides [Re(?3-SC6H4N?C(H)C6H4O)(?1-NNC4H3N2)(?2-HNNC4H3N2)]·0.6CH2Cl2 (3·0.6CH2Cl2). The analogous hydrazinopyridine complex of the Schiff base, [Re(?3-SC6H4N?C(H)C6H4O)(?1-NNC5H4N)(?2-HNNC5H4N)] (4), was also synthesized by reacting [ReCl3(?1-NNC5H4NH)(?2-HNNC5H4N)] with HSC6H4N?C(H)C6H4OH.

Frank J Femia; Xiaoyuan Chen; Kevin P Maresca; John W Babich; Jon Zubieta

2000-01-01

340

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

PubMed Central

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.

2012-01-01

341

Co(II) and Cd(II) Complexes Derived from Heterocyclic Schiff-Bases: Synthesis, Structural Characterisation, and Biological Activity  

PubMed Central

New monomeric cobalt and cadmium complexes with Schiff-bases, namely, N?-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]furan-2-carbohydrazide (L1) and N?-[(E)-(3-hydroxy-4-methoxyphenyl)methylidene]thiophene-2-carbohydrazide (L2) are reported. Schiff-base ligands L1 and L2 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)2]Cl2 (where M = Co(II) or Cd(II), L?=?L1 or L2) 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, 1H, and 13C 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.

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

2013-01-01

342

New acyclic 1,2,4-triazole-based Schiff base hydrazone: synthesis, characterization, spectrophotometric and computational studies.  

PubMed

A new 1,2,4-triazole-based Schiff base hydrazone with N, O, S donor set of atoms, H(4)L, has been prepared by condensation reaction of N,N'-bis(3-formyl-5-methylsalicylidene)ethane-1,2-diamine, H(2)L, with 4-amino-3-(4-pyridyl)-5-mercapto-1,2,4-triazole. The structure of H(4)L was characterized by using FT-IR, UV-Vis and (1)H NMR spectroscopic methods as well as elemental analysis data. The formation constants of copper(II), cadmium(II), mercury(II) and silver(I) complexes of H(4)L in DMSO were calculated using a hard model chemometrics method applying the spectrophotometric data. The protonation constants of H(4)L were also measured in DMSO-water (1:10) mixture. Furthermore, (1)H chemical shifts of H(4)L were studied by the gauge independent atomic orbital (GIAO) and continuous set of gauge transformations (CSGTs) methods at the level of density functional theory using B3LYP/6-311++G(*) basis sets in gas phase. The computed chemical shifts are in reasonably good agreement with the experimental data. PMID:23321219

Khanmohammadi, Hamid; Erfantalab, Malihe; Azimi, Golamhassan

2012-12-20

343

Aggregation-induced fluorescence behavior of triphenylamine-based schiff bases: the combined effect of multiple forces.  

PubMed

Eight triphenylamine (TPA)-based Schiff bases that exhibit different aggregation-induced emission (AIE) or aggregation-caused quenching (ACQ) behavior in tetrahydrofuran (THF)/water mixtures have been synthesized and characterized. The photophysical properties in solution, aqueous suspension, film, and the crystalline state along with their relationships were comparatively investigated. The single-crystal structures of 1-8 indicate that compact ?···? stacking or excimers induce fluorescence quenching of 1, 2, 5, and 7. However, the existence of J aggregates or multiple intra- and intermolecular interactions restrict the intramolecular vibration and rotation, enabling compounds 3, 4, 6, and 8 to exhibit good AIE character. The size and growth process of particles with different water fractions were studied using scanning electron microscopy, which demonstrated that smaller uniformly dispersed nanoparticles in the THF/water mixtures favor fluorescence emission. The above results suggest that the combined effects of multiple forces caused by structural variation have a great influence on their molecular packing, electronic structure, and aggregation-induced fluorescence properties. In addition, piezofluorochromic experiments verified the potential applications of 4 and 6. PMID:24050697

Yang, Mingdi; Xu, Dongling; Xi, Wengang; Wang, Lianke; Zheng, Jun; Huang, Jing; Zhang, Jingyan; Zhou, Hongping; Wu, Jieying; Tian, Yupeng

2013-10-03

344

New acyclic 1,2,4-triazole-based Schiff base hydrazone: Synthesis, characterization, spectrophotometric and computational studies  

NASA Astrophysics Data System (ADS)

A new 1,2,4-triazole-based Schiff base hydrazone with N, O, S donor set of atoms, H4L, has been prepared by condensation reaction of N,N'-bis(3-formyl-5-methylsalicylidene)ethane-1,2-diamine, H2L, with 4-amino-3-(4-pyridyl)-5-mercapto-1,2,4-triazole. The structure of H4L was characterized by using FT-IR, UV-Vis and 1H NMR spectroscopic methods as well as elemental analysis data. The formation constants of copper(II), cadmium(II), mercury(II) and silver(I) complexes of H4L in DMSO were calculated using a hard model chemometrics method applying the spectrophotometric data. The protonation constants of H4L were also measured in DMSO-water (1:10) mixture. Furthermore, 1H chemical shifts of H4L were studied by the gauge independent atomic orbital (GIAO) and continuous set of gauge transformations (CSGTs) methods at the level of density functional theory using B3LYP/6-311++G* basis sets in gas phase. The computed chemical shifts are in reasonably good agreement with the experimental data.

Khanmohammadi, Hamid; Erfantalab, Malihe; Azimi, Golamhassan

2013-03-01

345

Synthesis, structure, and single-molecule magnetic properties of rare-earth sandwich complexes with mixed phthalocyanine and Schiff base ligands.  

PubMed

Double- and quadruple-decker complexes of rare-earth metals with mixed phthalocyanine and Schiff base ligands have been synthesized and structurally and magnetically characterized. These complexes (see picture: Dy?pink, Ca?green, N?blue, C?black) extend the scope of sandwich-type tetrapyrrole-based rare-earth molecular materials. PMID:23281042

Wang, Hailong; Cao, Wei; Liu, Tao; Duan, Chunying; Jiang, Jianzhuang

2012-12-27

346

Nickel analysis in real samples by Ni(2+) selective PVC membrane electrode based on a new Schiff base.  

PubMed

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 1.0×10(-7) to 1.0×10(-2)molL(-1) with a slope of 30.0±0.3mV/decade of concentration. The limit of detection as determined from the intersection linear segment of the calibration plot is 5.1×10(-8)molL(-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 (?10s) and can be used for 17weeks 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

Tomar, Praveen Kumar; Chandra, Sulekh; Malik, Amrita; Kumar, Ankit

2013-08-29

347

Metal based photosensitizers of tetradentate Schiff base: Promising role in anti-tumor activity through singlet oxygen generation mechanism.  

PubMed

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 4.5×10(4)M(-1) and 4.2×10(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 5.7×10(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

Pradeepa, S M; Bhojya Naik, H S; Vinay Kumar, B; Indira Priyadarsini, K; Barik, Atanu; Ravikumar Naik, T R; Prabhakara, M C

2013-06-17

348

Metal based photosensitizers of tetradentate Schiff base: Promising role in anti-tumor activity through singlet oxygen generation mechanism  

NASA Astrophysics Data System (ADS)

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 4.5 × 104 M-1 and 4.2 × 104 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 5.7 × 104 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 365 nm, through 1O2 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.

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

349

Synthesis, characterization and electrochemical study of synthesis of a new Schiff base (H?cddi(t)butsalen) ligand and their two asymmetric Schiff base complexes of Ni(II) and Cu(II) with NN'OS coordination spheres.  

PubMed

A novel Schiff base (H(2)cddi(t)butsalen) ligand was prepared via condensation of Methyl-2-{N-(2'-aminoethane)}-amino-1-cyclopentenedithiocarboxylate(Hcden) and 3,5-di-tert-butyl-2-hydroxybenzaldehyde. The ligand and Ni(II) and Cu(II) complexes were characterized based on elemental analysis, IR, (1)H NMR, (13)C NMR, UV-Vis spectrometry and cyclic voltammetry. The structure of copper{methyl-2-{N-[2-(3,5-di-tert-butyl-2-hydroxyphenyl)methylidynenitrilo]ethyl}amino-1-cyclopentedithiocarboxylate has been determined by X-ray crystallography. The X-ray results confirm that the geometry of the complex is slightly distorted square-planar structure. The copper(II) ion coordinates to two nitrogen atoms from the imine moiety of the ligand, a sulfur atom the methyl dithiocarboxylate moiety and phenolic oxygen atom. PMID:22925979

Menati, Saeid; Azadbakht, Azadeh; Taeb, Abbas; Kakanejadifard, Ali; Khavasi, Hamid Reza

2012-08-03

350

Synthesis and Characterization of Some Amino Acid Derived Schiff Bases Bearing Nonionic Species as Corrosion Inhibitors for Carbon Steel in 2N HCl  

Microsoft Academic Search

A novel series of nonionic amino acid Schiff-Bases were synthesized and characterized using different spectroscopic tools to elucidate their chemical structures. The surface and thermodynamic properties of these compounds were studied using classical measurements including surface and interfacial tension and emulsification tendency. The surface parameters of these compounds including surface tension, critical micelle concentration (CMC), effectiveness (?cmc), efficiency (Pc20), maximum

N. A. Negm; M. F. Zaki

2009-01-01

351

Spectroscopic analyses on interaction of Amantadine-Salicylaldehyde, Amantadine-5-Chloro-Salicylaldehyde and Amantadine-o-Vanillin Schiff-Bases with bovine serum albumin (BSA).  

PubMed

In this work, three Tricyclo [3.3.1.1(3,7)] decane-1-amine (Amantadine) Schiff-Bases, Amantadine-Salicylaldehyde (AS), Amantadine-5-Chloro-Salicylaldehyde (AS-5-C) and Amantadine-o-Vanillin (AS-o-V), were synthesized by direct heating reflux method in ethanol solution and characterized by infrared spectrum and elementary analysis. Fluorescence quenching was used to study the interaction of these Amantadine Schiff-Bases (AS, AS-5-C and AS-o-V) with bovine serum albumin (BSA). According to fluorescence quenching calculations the bimolecular quenching constant (K(q)), apparent quenching constant (K(SV)), effective binding constant (K(A)) and corresponding dissociation constant (K(D)), binding site number (n) and binding distance (r) were obtained. The results show that these Amantadine Schiff-Bases can obviously bind to BSA molecules and the binding strength order is ASSchiff-Bases adopt different way to bind with BSA molecules. That is, the AS and AS-5-C are accessibility to tryptophan (Trp) residues more than the tyrosine (Tyr) residues, while the AS-o-V is equally close to the Tyr and Trp residues. PMID:21945126

Wang, Zhiqiu; Gao, Jingqun; Wang, Jun; Jin, Xudong; Zou, Mingming; Li, Kai; Kang, Pingli

2011-09-09

352

Molecular structures of 3d metal complexes with various Schiff bases studied by gas-phase electron diffraction and quantum-chemical calculations  

NASA Astrophysics Data System (ADS)

The present article summarizes the results of our studies of 3d metal complexes with various Schiff bases. Structural features, regularities of changes of the (M-N) and (M-O) bond lengths, as well as their correlation with electronic structure of the metal atom are discussed.

Tverdova, N. V.; Pelevina, E. D.; Giricheva, N. I.; Girichev, G. V.; Kuzmina, N. P.; Kotova, O. V.

2012-03-01

353

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  

Microsoft Academic Search

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

S. Djebbar-Sid; O Benali-Baitich; J. P Deloume

2001-01-01

354

Electrochemical study of some cobalt schiff base complexes and their methyl derivatives. Relation to the behaviour of the cobalt-carbon bond  

Microsoft Academic Search

Two series of methyl and nonmethyl cobalt complexes involving closely related quadridentate Schiff bases have been investigated. The use of nonsymmetrical or substituted ligands allows the reduction potential of the cobalt centre to be gradually modified. The data thus obtained are considered in connection with the ability of the cobalt complexes to alkylate tin (IV).

Jean-Pierre Costes; Gérard Cros; Marie-Hélène Darbieu; Jean-Pierre Laurent

1982-01-01

355

Electroless deposition of vanadium–Schiff base complex onto carbon nanotubes modified glassy carbon electrode: Application to the low potential detection of iodate, periodate, bromate and nitrite  

Microsoft Academic Search

The multiwall carbon nanotubes (MWCNTs) were used as an immobilization matrix to incorporate vanadium-Schiff base complex as electron transfer mediator onto a glassy carbon electrode surface. First, the preheated glassy carbon was subjected to abrasive immobilization of MWCNTs by gently rubbing the electrode surface on a filter paper supporting the carbon nanotubes. Second, the electrode surface was modified with casting

Abdollah Salimi; Hussein Mamkhezri; Sajjad Mohebbi

2006-01-01

356

Spectroscopic analyses on interaction of Amantadine-Salicylaldehyde, Amantadine-5-Chloro-Salicylaldehyde and Amantadine-o-Vanillin Schiff-Bases with bovine serum albumin (BSA)  

NASA Astrophysics Data System (ADS)

In this work, three Tricyclo [3.3.1.1(3,7)] decane-1-amine (Amantadine) Schiff-Bases, Amantadine-Salicylaldehyde (AS), Amantadine-5-Chloro-Salicylaldehyde (AS-5-C) and Amantadine-o-Vanillin (AS-o-V), were synthesized by direct heating reflux method in ethanol solution and characterized by infrared spectrum and elementary analysis. Fluorescence quenching was used to study the interaction of these Amantadine Schiff-Bases (AS, AS-5-C and AS-o-V) with bovine serum albumin (BSA). According to fluorescence quenching calculations the bimolecular quenching constant ( Kq), apparent quenching constant ( KSV), effective binding constant ( KA) and corresponding dissociation constant ( KD), binding site number ( n) and binding distance ( r) were obtained. The results show that these Amantadine Schiff-Bases can obviously bind to BSA molecules and the binding strength order is AS < AS-5-C = AS-o-V. Synchronous fluorescence spectroscopy reveals that these Amantadine Schiff-Bases adopt different way to bind with BSA molecules. That is, the AS and AS-5-C are accessibility to tryptophan (Trp) residues more than the tyrosine (Tyr) residues, while the AS-o-V is equally close to the Tyr and Trp residues.

Wang, Zhiqiu; Gao, Jingqun; Wang, Jun; Jin, Xudong; Zou, Mingming; Li, Kai; Kang, Pingli

2011-12-01

357

Synthesis, spectral characterization and biological activity of zinc(II) complexes with 3-substituted phenyl-4-amino-5-hydrazino-1, 2, 4-triazole Schiff bases.  

PubMed

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(2)O)(2)], [ZnL'(OAc)(2)(H(2)O)(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, (1)H NMR, (13)C 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. PMID:22029966

Singh, A K; Pandey, O P; Sengupta, S K

2011-09-10

358

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)

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.

Singh, A. K.; Pandey, O. P.; Sengupta, S. K.

359

An efficient method for solution-phase parallel synthesis of 2-quinoxalinol salen Schiff-base ligands.  

PubMed

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

Wu, Xianghong; Gorden, Anne E V

2007-05-12

360

A study on copper(II)-Schiff base-azide coordination complexes: Synthesis, X-ray structure and luminescence properties of [Cu(L)(N 3)]X (L = Schiff bases; X = ClO 4, PF 6)  

Microsoft Academic Search

Two Schiff bases N,N?-(bis(pyridin-2-yl)benzylidene)propane-1,3-diamine (pbpd) and N,N?-(bis(pyridin-2-yl)formylidene)butane-1,4-diamine (pfbd) have been prepared and used to synthesize copper(II) complexes. Four complexes of the type [Cu(L)(N3)]X (1–4) [L=pbpd; X=ClO4 (1); L=pbpd; X=PF6 (2); L=pfbd; X=ClO4 (3); L=pfbd; X=PF6 (4)] have been synthesized and characterized on the basis of microanalytical, spectroscopic, magnetic, electrochemical, luminescence and other physicochemical properties. Two representative complexes of the series,

Sk Hafijur Rahaman; Hoong-Kun Fun; Barindra Kumar Ghosh

2005-01-01

361

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

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

Asadi, Mozaffar; Asadi, Zahra; Torabi, Susan; Lotfi, Najmeh

2012-05-14

362

Spectral characterization, cyclic voltammetry, morphology, biological activities and DNA cleaving studies of amino acid Schiff base metal(II) complexes.  

PubMed

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

Neelakantan, M A; Rusalraj, F; Dharmaraja, J; Johnsonraja, S; Jeyakumar, T; Sankaranarayana Pillai, M

2008-06-22

363

Schiff base formation and recognition of amino sugars, aminoglycosides and biological polyamines by 2-formyl phenylboronic acid in aqueous solution.  

PubMed

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

Gutiérrez-Moreno, Nini J; Medrano, Felipe; Yatsimirsky, Anatoly K

2012-07-27

364

Solvent extraction of zirconium(IV) and uranium(VI) from chloride media with bidentate Schiff bases  

SciTech Connect

The systematic liquid-liquid extraction behavior of zirconium(IV) and uranium(VI) with bidentate Schiff bases (HSB) in benzene as the diluent has been studied. Quantitative extraction of zirconium(IV) has been achieved. Four consecutive extractions are, however, necessary for quantitative extraction of uranium(VI) at pH 6.0. The extracted species seem to be (Zr/sub 4/(OH)/sub 8/(H/sub 2/O)/sub 4/(HSB)/sub 6/)Cl/sub 8/ and ((UO/sub 2/)/sub 2/(OH)/sub 2/(HSB))Cl/sub 2/. The extraction efficiency is in the order: Zr/sup 4 +/ > Th/sup 4 +/ > UO/sub 2//sup 2 +/. It is possible to separate zirconium from thorium and uranium by solvent extraction with HSB. Exchange reaction technique has been employed for separation of thorium and uranium. 19 references, 3 figures, 1 table.

Panda, C.R.; Chakravortty, V.; Dash, K.C.

1985-12-01

365

Adsorption and inhibitive properties of a Schiff base for the corrosion control of carbon steel in saline water.  

PubMed

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

Samide, Adriana; Tutunaru, Bogdan

2011-01-01

366

Unexpected Assembly of a Novel Triply Bridged Diiron(II) Core by a Bidentate Schiff Base Ligand  

PubMed Central

The unusual dinucleating properties of a simple bidentate Schiff base (LH, 1) in the presence of weakly coordinating methanol solvent lead to the self-assembly of [FeII2(Lb)2(Lt)2(?-MeOH)] (2) (b and t refer to bridging and terminally bound ligands, respectively). Complex 2 is the first diiron(II) species in which the two metal centers are triply bridged by single atoms in an asymmetric fashion, involving both ?-OPh and ?-OHMe bridges. This binding mode produces an Fe···Fe distance of 3.139(1) Å. Dinucleation appears to be driven by a combination of ligand deficiency and solvent-mediated chemistry reminiscent of host–guest interactions. The presence of a ?-MeOH ligand is unprecedented in iron chemistry. Parallel-mode EPR spectra of complex 2 recorded at 4 K show an intense negative signal at g|| ? 16, suggesting the dimeric form exists in solution.

Smith, Aubrey L.; Day, Cynthia S.; Que, Lawrence; Zhou, Yuming; Bierbach, Ulrich

2009-01-01

367

Spectral properties of a simple azine Schiff base and its sensing ability towards protic environment through hydrogen bonding interaction  

NASA Astrophysics Data System (ADS)

A simple azine linkage containing Schiff base p-N,N-diethylaminobenzaldazine (PDEAB) has been synthesized and its spectroscopic properties have been investigated using steady state absorption and fluorescence measurement. Both the absorption and emission studies indicate that the compound PDEAB forms intermolecular hydrogen bond with protic solvents. The formation of intermolecular hydrogen bond between PDEAB and protic solvents is further verified by Quantum chemical calculation using Density Functional Theory (DFT) (B3LYP/6-31++G(d,p)) and Natural Bond Orbital (NBO) analysis. The non-fluorescent nature (fluorescence off) of PDEAB in aprotic environment can be switched over to a fluorescent system (fluorescence on) in presence of protic solvents and hence this molecule can be used as highly sensitive fluorosensor for protic solvent in aprotic medium like ACN or DOX.

Ray, Debarati; Dalapati, Sasanka; Guchhait, Nikhil

2013-11-01

368

Preparation and characterization of different two types of di-?-oxo dimanganese(IV) complexes with tetradentate Schiff bases  

Microsoft Academic Search

Novel di-?-oxo dimanganese(IV) complexes with a series of tetradentate Schiff base ligands have been prepared and characterized by spectroscopy, magnetic susceptibility, electrochemical measurements and X-ray crystallography. The di-?-oxo dimanganese(IV) complexes, [MnIV(?-salophen)(?-O)], 1 (salophen H2 = N,N?-disalicylidene-1,2-diaminobenzen), [Mn(?-salen)(?-O)]2, 2 (salenH2 = N,N?-disalicylidene-1,2-diaminoethane), [Mn(salen)(?-O)]2, 3, [Mn(salipn)(?-O)]2, 4 (salipnH2 = N,N?-disalicylidene-1,2-diaminopropane) and [Mn(salbn)(?-O)]2, 5 (salbnH2 = N,N?-disalicylidene-1,4-diaminobutane), have been found to be obtained

Hitoshi Torayama; Tamao Nishide; Hideyuki Asada; Manabu Fujiwara; Takayuki Matsushita

1998-01-01

369

Synthesis, characterization and crystal structures of some four coordinated nickel(II) complexes with tridentate Schiff base ligands  

Microsoft Academic Search

A number of Ni(II) complexes with tridentate Schiff base ligands with a N2O donor set and coordinating NNN? and SCN? anions have been synthesized and characterized by analytical, spectroscopic and electrochemical techniques. X-ray structure analyses of three of these complexes [L1Ni(NNN)] (1), [L2Ni(NNN)] (2) and [L3Ni(NCS)] (6) [HL1=Me2NCH2CH2N(Me)C6H4OH, HL2=Et2NCH2CH2N(H)C6H4OH, HL3=Et2NCH2CH2N(H)C6H3BrOH] show that the nickel atom has a square planar geometry.

Nijhuma Mondal; Volker Gramilich; S. Ozra Ghodsi

2001-01-01

370

New Cu(II) complexes with polydentate chelating Schiff base ligands: Synthesis, structures, characterisations and biochemical activity studies  

Microsoft Academic Search

We have reported herein the synthesis of three new Cu(II) complexes of tri- and tetradentate Schiff base ligands containing\\u000a N3 or N4 donor set along with terminal NNN? or SCN? ligands: [L1Cu(NCS)]ClO4 (1), [L2Cu(NCS)2] (2) and [L3Cu(NNN)]ClO4 (3) [L1 = NC5H4C(CH3)=N(CH2)3N=C(CH3)C5H4N, L2= Me2N–(CH2)3–N=C(CH3)C5H4N and L3 = NC5H4CH=N–(CH2)4–N=CHC5H4N]. The complexes have been systematically characterised by elemental, spectroscopic and electrochemical techniques. Antimicrobial\\u000a activities

Brajagopal Samanta; Joy Chakraborty; C. R. Choudhury; S. K. Dey; D. K. Dey; S. R. Batten; P. Jensen; Glenn P. A. Yap; Samiran Mitra

2007-01-01

371

The application of some polydentate Schiff base compounds containing aminic nitrogens as corrosion inhibitors for mild steel in acidic media  

Microsoft Academic Search

The effect of three Schiff base compounds namely, (E)-2-(1-(2-(2-hydroxyethylamino)ethylimino)ethyl)phenol(I), 2,2?-(1E,1?E)-1,1?-(2,2?-azanediylbis(ethane-2,1-diyl)bis(azan-1-yl-1-ylidene))bis(ethan-1-yl-1-ylidene)diphenol(II) and 2,2?-((2E,12E)-3,6,9,12-tetraazatetradeca-2,12-diene-2,13-diyl)diphenol(III) on the corrosion behavior of steel in 2M HCl solution has been investigated at 298K by weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. The inhibition efficiencies obtained from all methods employed are in good agreement. Results show compound III to be the best inhibitor

Kaan C. Emregül; Ece Düzgün; Orhan Atakol

2006-01-01

372

Synthesis and DNA binding studies of Mg(II) complex of Schiff base derived from vanillin and L-tryptophan.  

PubMed

The Mg(II) complex of Schiff base (K[HL]) derived from vanillin and L-tryptophan could bind with herring sperm DNA. The binding behaviors between them in physiological pH environment (pH 7.40) have been studied by spectroscopy, cyclic voltammetry and viscosity methods. Binding ratios of n(Mg(II)): n(K[HL]) = 1:1 and n(Mg(II)L): n(DNA) = 5:1 were confirmed. The obtained thermodynamic parameters suggest that the interaction between Mg(II)L and DNA is driven mainly by entropy. Combined with fluorimeteric studies, cyclic voltammetry, CD spectroscopy and viscosity methods, the results indicate the interaction modes between Mg(II)L and DNA are mainly with intercalation and involving some electrostatic interaction. PMID:21259163

Zhang, Yan; Wang, Xingming; Ding, Lisheng

2011-01-01

373

Binuclear ruthenium(III) Schiff base complexes bearing N(4)O(4) donors and their catalytic oxidation of alcohols.  

PubMed

An interesting series of binuclear ruthenium(III) Schiff base complexes bearing bis-salophen/bis-naphophen units of the general composition [(EPh(3))(X)Ru-L-Ru(X)(EPh(3))] (where E=P or As; X=Cl or Br; L=binucleating dianionic tetradentate ligands) have been synthesized and characterized by analytical (elemental analysis, magnetic susceptibility measurements), spectral (FT-IR, UV-vis and EPR) and electrochemical methods. These ruthenium(III) complexes have two N(2)O(2) metal binding sites, which are linked to each other with a biphenyl bridge and acts as potential catalyst for oxidation of wide range of primary and secondary alcohols to corresponding aldehydes or ketones with moderate to high conversion in the presence of N-methylmorpholine-N-oxide (NMO). The formation of high-valent Ru(V)=O species as a catalytic active intermediate is proposed for the catalytic processes. PMID:18358767

Venkatachalam, G; Raja, N; Pandiarajan, D; Ramesh, R

2008-02-12

374

Spectral properties of a simple azine Schiff base and its sensing ability towards protic environment through hydrogen bonding interaction.  

PubMed

A simple azine linkage containing Schiff base p-N,N-diethylaminobenzaldazine (PDEAB) has been synthesized and its spectroscopic properties have been investigated using steady state absorption and fluorescence measurement. Both the absorption and emission studies indicate that the compound PDEAB forms intermolecular hydrogen bond with protic solvents. The formation of intermolecular hydrogen bond between PDEAB and protic solvents is further verified by Quantum chemical calculation using Density Functional Theory (DFT) (B3LYP/6-31++G(d,p)) and Natural Bond Orbital (NBO) analysis. The non-fluorescent nature (fluorescence off) of PDEAB in aprotic environment can be switched over to a fluorescent system (fluorescence on) in presence of protic solvents and hence this molecule can be used as highly sensitive fluorosensor for protic solvent in aprotic medium like ACN or DOX. PMID:23835054

Ray, Debarati; Dalapati, Sasanka; Guchhait, Nikhil

2013-06-20

375

Synthesis, biological assay in vitro and molecular docking studies of new Schiff base derivatives as potential urease inhibitors.  

PubMed

A series of new and novel Schiff base derivatives were synthesized and investigated as potential new inhibitors of Jack bean urease. The most potent compounds were 3f with (K(i) = 0.09 ?M) and 3k (K(i) = 0.122 ?M). A pure competitive mechanism of inhibition was observed. Molecular docking studies were also performed to illustrate the binding mode of the compounds. Docking studies were performed on both enzymes from Jack bean urease and H. pylori urease. It was observed that both share the same binding mode. The binding sites of the two urease structures also aligned very well indicating the similarity in binding sites of the enzymes. PMID:21981981

Aslam, Muhammad Adil S; Mahmood, Shams-ul; Shahid, Mohammad; Saeed, Aamer; Iqbal, Jamshed

2011-09-16

376

Synthesis, spectroscopic characterization and comparative DNA binding studies of Schiff base complexes derived from L-leucine and glyoxal  

NASA Astrophysics Data System (ADS)

The mononuclear Schiff base complexes of the type, [ML(CH 3OH) 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, 1H NMR and 13C 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.

Shakir, Mohammad; Shahid, Nida; Sami, Naushaba; Azam, Mohammad; Khan, Asad U.

2011-11-01

377

Two tridentate Schiff base ligands and their mononuclear cobalt (III) complexes: Synthesis, characterization, antibacterial and antifungal activities  

NASA Astrophysics Data System (ADS)

Two Schiff base ligands (HL1, HL2) and their Co(III) complexes, [Co(HL1)(L1)] (1) and [Co(HL2)(L2)] (2) [where HL1 = 2-((E)-(2-hydroxyethylimino)methyl)-4-chlorophenol and HL2 = 2-((E)-(2-hydroxyethylimino)methyl)-4-bromophenol] were synthesized and characterized using spectroscopic methods. The crystal structures of 1 and 2 have been re-determined by single crystal diffraction at 100 K. The ligands and their Co(III) complexes were screened for antibacterial and antifungal activities by the disc diffusion, microdilution broth and single spore culture techniques. The antimicrobial activity of the Co(III) complexes and the free ligands exhibit antimicrobial properties and the Co(III) complexes show enhanced inhibitory activity compared with their parent ligand.

Gungor, Elif; Celen, Selma; Azaz, Dilek; Kara, Hulya

378

Electrochemical and quantum chemical studies of some Schiff bases on the corrosion of steel in H2SO4 solution  

NASA Astrophysics Data System (ADS)

The efficiency, as steel-corrosion inhibitors in 0.1 M and 1 M H2SO4, of two Schiff bases, 2-{[(4-methoxyphenyl)imino]methyl}phenol and 1-{[(4-methoxyphenyl)imino]methyl}-2-naphthol, (abbreviated SB-1 and SB-2, respectively) was investigated by Tafel extrapolation and linear polarization methods. Corrosion parameters and adsorption isotherms were determined from current potential curves. It was found that the percent inhibition efficiencies (?%) and surface coverage (?) increase with an increases in the concentrations of inhibitors. The results showed that these compounds act as good corrosion inhibitors especially at high concentrations. The adsorption of used compounds on the steel surface obeys Langmuir's isotherm. Obvious correlation was found between corrosion inhibition efficiency and quantum chemical parameters obtained by B3LYP/6-31g(d) method. The obtained theoretical results have been compared with the experimental findings.

Hasanov, Rovshan; Sad?ko?lu, Murat; Bilgiç, Semra

2007-02-01

379

Two tridentate Schiff base ligands and their mononuclear cobalt (III) complexes: Synthesis, characterization, antibacterial and antifungal activities.  

PubMed

Two Schiff base ligands (HL1, HL2) and their Co(III) complexes, [Co(HL1)(L1)] (1) and [Co(HL2)(L2)] (2) [where HL1=2-((E)-(2-hydroxyethylimino)methyl)-4-chlorophenol and HL2=2-((E)-(2-hydroxyethylimino)methyl)-4-bromophenol] were synthesized and characterized using spectroscopic methods. The crystal structures of 1 and 2 have been re-determined by single crystal diffraction at 100K. The ligands and their Co(III) complexes were screened for antibacterial and antifungal activities by the disc diffusion, microdilution broth and single spore culture techniques. The antimicrobial activity of the Co(III) complexes and the free ligands exhibit antimicrobial properties and the Co(III) complexes show enhanced inhibitory activity compared with their parent ligand. PMID:22522298

Gungor, Elif; Celen, Selma; Azaz, Dilek; Kara, Hulya

2012-03-17

380

Synthesis, spectroscopic characterization and crystal structure of novel NNNN-donor ?-bis(bidentate) tetraaza acyclic Schiff base ligands  

NASA Astrophysics Data System (ADS)

Novel NNNN-donor ?-bis(bidentate) tetraaza acyclic Schiff base ligands with different substituents (CF3, N(CH3)2 or OH groups) were synthesized by the condensation reaction of triethylenetetramine with 4-substituted benzaldehydes. Triethylenetetramine tris(4-trifluoromethylbenzylidene) (TTFMB), triethylenetetramine tris(4-dimethylaminobenzylidene) (TTDMB) and triethylenetetramine tris(2,4-dihydroxybenzylidene) (TTDHB) were formed as N4 donor ligands. The formation of a five-membered imidazolidine ring from the ethylenediamine backbone as a spacer-cumbridging unit gives rise to a new type of imidazolidine ligand. The structure of the TTFMB and TTDMB were determined by single crystal X-ray crystallography. The synthesized ligands have been characterized on the basis of the results of cyclic voltammetry (CV) and spectroscopic studies viz. FT-IR spectroscopy (FT-IR), mass spectroscopy (MS) and UV-Vis spectroscopy (UV-Vis).

Habibi, Mohammad Hossein; Shojaee, Elahe; Nichol, Gary S.

2012-12-01

381

Synthesis, spectroscopic characterization and crystal structure of novel NNNN-donor ?-bis(bidentate) tetraaza acyclic Schiff base ligands.  

PubMed

Novel NNNN-donor ?-bis(bidentate) tetraaza acyclic Schiff base ligands with different substituents (CF(3), N(CH(3))(2) or OH groups) were synthesized by the condensation reaction of triethylenetetramine with 4-substituted benzaldehydes. Triethylenetetramine tris(4-trifluoromethylbenzylidene) (TTFMB), triethylenetetramine tris(4-dimethylaminobenzylidene) (TTDMB) and triethylenetetramine tris(2,4-dihydroxybenzylidene) (TTDHB) were formed as N(4) donor ligands. The formation of a five-membered imidazolidine ring from the ethylenediamine backbone as a spacer-cumbridging unit gives rise to a new type of imidazolidine ligand. The structure of the TTFMB and TTDMB were determined by single crystal X-ray crystallography. The synthesized ligands have been characterized on the basis of the results of cyclic voltammetry (CV) and spectroscopic studies viz. FT-IR spectroscopy (FT-IR), mass spectroscopy (MS) and UV-Vis spectroscopy (UV-Vis). PMID:23010628

Habibi, Mohammad Hossein; Shojaee, Elahe; Nichol, Gary S

2012-09-01

382

Dependence of photochemical reactivity of the all-trans retinal protonated Schiff base on the solvent and the excitation wavelength.  

PubMed

An all-optical experimental technique aimed at measuring photoisomerization quantum yield (phi) of the all-trans protonated Schiff base of retinal in solution has been implemented. Upon the increase in the excitation wavelength from 400 to 540 nm a slight increase in phi from 0.16 +/- 0.03 to 0.20 +/- 0.02 is observed in the chromophore dissolved in methanol, whereas the phi value of the one dissolved in acetonitrile varies only from 0.22 +/- 0.03 (400 nm) to 0.23 +/- 0.04 (540 nm). The results suggest that dissipation of the excited-state vibrational energy excess, along with environment-induced modifications of the potential energy surfaces are necessary for an efficient retinal photoisomerization in both solvent and protein environment. PMID:20132512

Zgrabli?, Goran; Ricci, Maria; Novello, Anna Maria; Parmigiani, Fulvio

2010-01-27

383

Schiff's base derivatives bearing nitroimidazole moiety: New class of antibacterial, anticancer agents and potential EGFR tyrosine kinase inhibitors.  

PubMed

New Schiff's base derivatives 5a-5h have been synthesized by reaction between 1-(4-bromophenyl)-2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethanone 3 and various benzohydrazide 4a-4h in presence of nickel (II) nitrate as a catalyst in ethanol at room temperature in good yield (54-88%). All compounds were tested for antibacterial as well as anticancer and inhibition of EGFR. Of the compounds studied, compounds 5d, 5f and 5g in the case of antiproliferation and inhibition of EGFR as well as compounds 5b, 5c, 5e and 5h in the case of antibacterial activity were found to be most effective compounds in the series. Compound 5f shows effective inhibition (IC50=0.21±0.02?M) by binding in to the active pocket of EGFR receptor with minimum binding energy (?Gb=-49.4869kcal/mol). PMID:24144854

Makawana, Jigar A; Sun, Juan; Zhu, Hai-Liang

2013-10-08

384

Enhanced catalytic activity of zeolite encapsulated Fe(III)-Schiff-base complexes for oxidative coupling of 2-napthol.  

PubMed

Iron(III) Schiff-base complexes of general formula [Fe(L)(2)Cl]·2H(2)O, where L = N,?-bis(salicylidene)ethylenediamine and N,N?-disalicylidene-1,2-phenylenediamine have been encapsulated within various alkali exchanged zeolites viz. LiY, NaY, and KY by flexible ligand method. The encapsulated complexes are characterized by EDX, scanning electron microscopy (SEM), powder X-ray diffraction (XRD), FT-IR, UV-vis, diffuse reflectance spectroscopy (DRS), electron spin resonance spectroscopy (ESR) and cyclic voltammetry studies. The diffuse reflectance UV-vis spectra of encapsulated complexes show a dramatic red shift of the charge transfer band with increasing electropositivity of the exchangeable cations. The electrochemical analysis predicts the shifting of the reduction potential toward negative values with increasing size of the alkali exchanged cations. The zeolite encapsulated Schiff-base complexes of iron are found to be catalytically active toward the oxidative coupling of 2-napthol. Metal complexes incorporated in potassium exchanged zeolite-Y are found to be more effective for catalytic conversion of 2-naphthol to binaphthol and induces higher selectivity toward the R-conformation. The catalytic conversion of 2-napthol to BINOL is found to depend on the reduction potential of the catalyst, with a more negative reduction potential being better for the catalytic conversion. Density functional calculation is being carried out on both the neat Fe-Salen and Fe-Salophen complexes and those encapsulated in NaY zeolite to investigate change in structural parameters, energies of the HOMO and LUMO, and global hardness and softness. Fukui functions, as local descriptors, are used to analyze the hard-hard interaction at a particular site of the complexes. PMID:22256783

Bania, Kusum K; Bharali, Dipsikha; Viswanathan, B; Deka, Ramesh C

2012-01-18

385

Factors that differentiate the H-bond strengths of water near the Schiff bases in bacteriorhodopsin and Anabaena sensory rhodopsin.  

PubMed

Bacteriorhodopsin (BR) functions as a light-driven proton pump, whereas Anabaena sensory rhodopsin (ASR) is believed to function as a photosensor despite the high similarity in their protein sequences. In Fourier transform infrared (FTIR) spectroscopic studies, the lowest O-D stretch for D(2)O was observed at ?2200 cm(-1) in BR but was significantly higher in ASR (>2500 cm(-1)), which was previously attributed to a water molecule near the Schiff base (W402) that is H-bonded to Asp-85 in BR and Asp-75 in ASR. We investigated the factors that differentiate the lowest O-D stretches of W402 in BR and ASR. Quantum mechanical/molecular mechanical calculations reproduced the H-bond geometries of the crystal structures, and the calculated O-D stretching frequencies were corroborated by the FTIR band assignments. The potential energy profiles indicate that the smaller O-D stretching frequency in BR originates from the significantly higher pK(a)(Asp-85) in BR relative to the pK(a)(Asp-75) in ASR, which were calculated to be 1.5 and -5.1, respectively. The difference is mostly due to the influences of Ala-53, Arg-82, Glu-194-Glu-204, and Asp-212 on pK(a)(Asp-85) in BR and the corresponding residues Ser-47, Arg-72, Ser-188-Asp-198, and Pro-206 on pK(a)(Asp-75) in ASR. Because these residues participate in proton transfer pathways in BR but not in ASR, the presence of a strongly H-bonded water molecule near the Schiff base ultimately results from the proton-pumping activity in BR. PMID:22865888

Saito, Keisuke; Kandori, Hideki; Ishikita, Hiroshi

2012-08-04

386

Synthesis and crystal structure of Schiff bases obtained by condensation of 2-aminopyridines with acrylic aldehydes  

Microsoft Academic Search

We synthesized a series of novel imines by reactions of 2-amino-4-methylpyridine with (hetero)aromatic derivatives of acrolein in the presence of molecular sieves (as a dehydrating and acid-catalyzing agent). We determined the molecular and crystal structure of two 2-pyridylazomethines containing the CH=CH–CH=N group by X-ray diffraction analysis.

I. Iovel; L. Golomba; S. Belyakov; E. Lukevics

2000-01-01

387

Aluminium(III)-selective electrode based on a newly synthesized tetradentate Schiff base.  

PubMed

A PVC membrane electrode for aluminium ion based on bis(5-phenyl azo salicylaldehyde) 2,3-naphthalene diimine (5PHAZOSALNPHN) as an ion carrier was developed. The electrode exhibits a Nernstian slope of 19.3+/-0.8 mV per decade and a linear range of 5.0x10(-6)-1.0x10(-2) M for Al(NO(3))(3). The limit of detection is 2.5x10(-6) M. It has a fast response time of about 10 s and can be used for at least 10 weeks without observing any deviation. The proposed membrane sensor revealed good selectivity for Al(3+) over a wide variety of other metal ions and could be used in pH range of 2.9-5.0. It was used as an indicator electrode in potentiometric titration of aluminium ion. PMID:18968765

Abbaspour, A; Esmaeilbeig, A R; Jarrahpour, A A; Khajeh, B; Kia, R

2002-08-23

388

Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole.  

PubMed

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(HL(1)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-p-tolylallyl]phenol(HL(2)), 2-[1-(3-(1H-imidazol-1-yl)propylimino)-3-4-nitrophenylallyl]phenol(HL(3)). 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. PMID:22169028

Kalanithi, M; Rajarajan, M; Tharmaraj, P; Sheela, C D

2011-11-23

389

Spectral, biological screening of metal chelates of chalcone based Schiff bases of N-(3-aminopropyl) imidazole  

NASA Astrophysics Data System (ADS)

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.

Kalanithi, M.; Rajarajan, M.; Tharmaraj, P.; Sheela, C. D.

2012-02-01

390

Fiber optic pH sensing with long wavelength excitable Schiff bases in the pH range of 7.0–12.0  

Microsoft Academic Search

Most of the fluorescent pH probes work near neutral or acidic regions of the pH scale. In this work, two different fluorescent Schiff bases, chloro phenyl imino propenyl aniline (CPIPA) and nitro phenyl imino propenyl aniline (NPIPA), have been investigated for pH sensing in the alkaline region. Absorption and emission based spectral data, quantum yield, fluorescence lifetime, photostability and acidity

Sibel Derinkuyu; Kadriye Ertekin; Ozlem Oter; Serpil Denizalti; Engin Cetinkaya

2007-01-01

391

Catalytic formation of ethylene carbonate from supercritical carbon dioxide\\/ethylene oxide mixture with tetradentate Schiff-base complexes as catalyst  

Microsoft Academic Search

Various tetradentate Schiff-base aluminum complexes (designated as SalenAlX) were prepared and used as catalysts for the synthesis of ethylene carbonate from supercritical carbon dioxide\\/ethylene oxide mixture. Their catalytic activities can be markedly enhanced in the presence of a Lewis base or quaternary salt. With SalenAlCl\\/n-Bu4NBr as catalyst, the formation rate of ethylene carbonate is up to 2220 turnovers\\/h and about

Xiao-Bing Lu; Xiou-Juan Feng; Ren He

2002-01-01

392

8Hydroxyquinoline5-carbaldehyde Schiff-base as a highly selective and sensitive Al 3+ sensor in weak acid aqueous medium  

Microsoft Academic Search

In the paper, a novel fluorescent sensor (1) based on 8-hydroxyquinoline carbaldehyde Schiff-base was synthesized and characterized. This fluorescent sensor exhibited high selectivity for Al3+ over other metal ions with the detection limit reaching below 10?7M under weak acid aqueous conditions. These suggested that 1 could be served as a highly selective and sensitive fluorescence sensor for aluminum ion in

Xin-hui Jiang; Bao-dui Wang; Zheng-yin Yang; Yong-chun Liu; Tian-rong Li; Zeng-chen Liu

2011-01-01

393

Synthesis and characterization of Co(II), Ni(II), Cu(II) and Zn(II) complexes of tridentate Schiff base derived from vanillin and dl-?-aminobutyric acid  

Microsoft Academic Search

Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from vanillin and dl-?-aminobutyric acid were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, magnetic measurements, powder XRD and biological activity. The analytical data show the composition of the metal complex to be [ML(H2O)], where L is the Schiff base ligand. The conductance data indicate that

M. Sivasankaran Nair; R. Selwin Joseyphus

2008-01-01

394

Synthesis, characterization and biological studies of some Co(II), Ni(II) and Cu(II) complexes derived from indole-3-carboxaldehyde and glycylglycine as Schiff base ligand  

Microsoft Academic Search

The Schiff base ligand derived from indole-3-carboxaldehyde(indal) and glycylglycine(glygly) were synthesized and characterized by elemental analysis, IR, electronic spectrum, 1H NMR and mass spectrum. Co(II), Ni(II) and Cu(II)–indal-glygly Schiff base complexes were synthesized and characterized by elemental analysis, molar conductance, IR, electronic spectra, magnetic measurements, ESR, electrochemical studies, TGA, DSC analysis, XRD and SEM. Conductance measurements indicate that the above

R. Selwin Joseyphus; M. Sivasankaran Nair

2010-01-01

395

Fiber optic pH sensing with long wavelength excitable Schiff bases in the pH range of 7.0-12.0.  

PubMed

Most of the fluorescent pH probes work near neutral or acidic regions of the pH scale. In this work, two different fluorescent Schiff bases, chloro phenyl imino propenyl aniline (CPIPA) and nitro phenyl imino propenyl aniline (NPIPA), have been investigated for pH sensing in the alkaline region. Absorption and emission based spectral data, quantum yield, fluorescence lifetime, photostability and acidity constant (pK(a)) of the Schiff bases were determined in conventional solvents and in PVC. The long wavelength excitable immobilized Schiff bases CPIPA (lambda(ex)=556 nm) and NPIPA (lambda(ex)=570 nm) exhibited absorption and emission based optical response to proton in the pH range of 8.0-12.0 and 7.0-12.0, respectively. Response of the CPIPA was fully reversible within the dynamic working range. The response times were between 3-13 min. A relative signal change of 95% and 96% have been achieved for sensor dyes of CPIPA and NPIPA, respectively. The CPIPA displayed better fluorescence quantum yield (varphi(F)=3.7 x 10(-1)) and higher matrix compatibility compared to NPIPA (varphi(F)=1.6 x 10(-1)) in immobilized PVC. The CPIPA and NPIPA exhibited a slight cross sensitivity to the ions of Hg(+) and Fe(3+), respectively. PMID:17386792

Derinkuyu, Sibel; Ertekin, Kadriye; Oter, Ozlem; Denizalti, Serpil; Cetinkaya, Engin

2007-02-06

396

Aspartate-Histidine Interaction in the Retinal Schiff Base Counterion of the Light-Driven Proton Pump of Exiguobacterium sibiricum†  

PubMed Central

One of the distinctive features of eubacterial retinal based proton pumps, proteorhodopsins, xanthorhodopsin and others, is hydrogen bonding of the key aspartate residue, the counterion to the retinal Schiff base, to a histidine. We describe properties of the recently found eubacterium proton pump from Exiguobacterium sibiricum (named ESR) expressed in E. coli, especially features that depend on Asp-His interaction, the protonation state of the key aspartate, Asp85, and its ability to accept proton from the Schiff base during the photocycle. Proton pumping by liposomes and E. coli cells containing ESR occurs in a broad pH range above pH 4.5. Large light-induced pH changes indicate that ESR is a potent proton pump. Replacement of His57 with methionine or asparagine strongly affects the pH dependent properties of ESR. In the H57M mutant a dramatic decrease in the quantum yield of chromophore fluorescence emission and a 45 nm blue shift of the absorption maximum upon raising the pH from 5 to 8 indicates deprotonation of the counterion with a pKa of 6.3, which is also the pKa at which the M intermediate is observed in the photocycle of the protein solubilized in detergent (DDM). This is in contrast with the wild type protein, in which the same experiments show that the major fraction of Asp85 is deprotonated at pH > 3 and that it protonates only at low pH, with a pKa of 2.3. The M intermediate in the wild type photocycle accumulates only at high pH, with an apparent pKa of 9 from deprotonation of a residue interacting with Asp85, presumably His57. In liposomes reconstituted with ESR the pKas for M formation and spectral shifts are 2–3 pH units lower than in DDM. The distinctively different pH dependencies of the protonation of Asp85 and the accumulation of the M intermediate in the wild type protein vs. the H57M mutant indicate that there is strong Asp-His interaction, which substantially lowers the pKa of Asp85 by stabilizing its deprotonated state.

Balashov, S.P.; Petrovskaya, L.E.; Lukashev, E.P.; Imasheva, E.S.; Dioumaev, A.K.; Wang, J.M.; Sychev, S.V.; Dolgikh, D.A.; Rubin, A.B.; Kirpichnikov, M.P.; Lanyi, J.K.

2012-01-01

397

Axial ligand exchange of N-heterocyclic cobalt(III) Schiff base complexes: molecular structure and NMR solution dynamics.  

PubMed

The kinetic and thermodynamic ligand exchange dynamics are important considerations in the rational design of metal-based therapeutics and therefore, require detailed investigation. Co(III) Schiff base complex derivatives of bis(acetylacetone)ethylenediimine [acacen] have been found to be potent enzyme and transcription factor inhibitors. These complexes undergo solution exchange of labile axial ligands. Upon dissociation, Co(III) irreversibly interacts with specific histidine residues of a protein, and consequently alters structure and causes inhibition. To guide the rational design of next generation agents, understanding the mechanism and dynamics of the ligand exchange process is essential. To investigate the lability, pH stability, and axial ligand exchange of these complexes in the absence of proteins, the pD- and temperature-dependent axial ligand substitution dynamics of a series of N-heterocyclic [Co(acacen)(X)(2)](+) complexes [where X = 2-methylimidazole (2MeIm), 4-methylimidazole (4MeIm), ammine (NH(3)), N-methylimidazole (NMeIm), and pyridine (Py)] were characterized by NMR spectroscopy. The pD stability was shown to be closely related to the nature of the axial ligand with the following trend toward aquation: 2MeIm > NH(3) ? 4MeIm > Py > Im > NMeIm. Reaction of each [Co(III)(acacen)(X)(2)](+) derivative with 4MeIm showed formation of a mixed ligand Co(III) intermediate via a dissociative ligand exchange mechanism. The stability of the mixed ligand adduct was directly correlated to the pD-dependent stability of the starting Co(III) Schiff base with respect to [Co(acacen)(4MeIm)(2)](+). Crystal structure analysis of the [Co(acacen)(X)(2)](+) derivatives confirmed the trends in stability observed by NMR spectroscopy. Bond distances between the Co(III) and the axial nitrogen atoms were longest in the 2MeIm derivative as a result of distortion in the planar tetradentate ligand, and this was directly correlated to axial ligand lability and propensity toward exchange. PMID:23282130

Manus, Lisa M; Holbrook, Robert J; Atesin, Tulay A; Heffern, Marie C; Harney, Allison S; Eckermann, Amanda L; Meade, Thomas J

2013-01-02

398

Aspartate-histidine interaction in the retinal schiff base counterion of the light-driven proton pump of Exiguobacterium sibiricum.  

PubMed

One of the distinctive features of eubacterial retinal-based proton pumps, proteorhodopsins, xanthorhodopsin, and others, is hydrogen bonding of the key aspartate residue, the counterion to the retinal Schiff base, to a histidine. We describe properties of the recently found eubacterium proton pump from Exiguobacterium sibiricum (named ESR) expressed in Escherichia coli, especially features that depend on Asp-His interaction, the protonation state of the key aspartate, Asp85, and its ability to accept a proton from the Schiff base during the photocycle. Proton pumping by liposomes and E. coli cells containing ESR occurs in a broad pH range above pH 4.5. Large light-induced pH changes indicate that ESR is a potent proton pump. Replacement of His57 with methionine or asparagine strongly affects the pH-dependent properties of ESR. In the H57M mutant, a dramatic decrease in the quantum yield of chromophore fluorescence emission and a 45 nm blue shift of the absorption maximum with an increase in the pH from 5 to 8 indicate deprotonation of the counterion with a pK(a) of 6.3, which is also the pK(a) at which the M intermediate is observed in the photocycle of the protein solubilized in detergent [dodecyl maltoside (DDM)]. This is in contrast with the case for the wild-type protein, for which the same experiments show that the major fraction of Asp85 is deprotonated at pH >3 and that it protonates only at low pH, with a pK(a) of 2.3. The M intermediate in the wild-type photocycle accumulates only at high pH, with an apparent pK(a) of 9, via deprotonation of a residue interacting with Asp85, presumably His57. In liposomes reconstituted with ESR, the pK(a) values for M formation and spectral shifts are 2-3 pH units lower than in DDM. The distinctively different pH dependencies of the protonation of Asp85 and the accumulation of the M intermediate in the wild-type protein versus the H57M mutant indicate that there is strong Asp-His interaction, which substantially lowers the pK(a) of Asp85 by stabilizing its deprotonated state. PMID:22738070

Balashov, S P; Petrovskaya, L E; Lukashev, E P; Imasheva, E S; Dioumaev, A K; Wang, J M; Sychev, S V; Dolgikh, D A; Rubin, A B; Kirpichnikov, M P; Lanyi, J K

2012-07-10

399

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)

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.

Lee, Min-Hee; Kim, Bo-Ra; Kim, Ho-Tae

2007-07-01

400

Synthesis, characterization, spectroscopic and thermodynamic studies of charge transfer interaction of a new water-soluble cobalt(II) Schiff base complex with imidazole derivatives.  

PubMed

The water-soluble cobalt(II) tetradentate Schiff base complex [Co(II)L](ClO4)(2), L: (N,N'-bis(5-[(triphenylphosphonium)-methyl]salicylidine)-o-phenylenediamineperchlorate has been synthesized and characterized. This complex forms charge transfer (CT) complexes with imidazole and 1-methylimidazole. The formation constant, molar absorptivity (epsilon'), and thermodynamic parameters for charge transfer complexes formation of cobalt(II) Schiff base complexes with imidazole derivatives were determined by using UV-vis spectrophotometric method in aqueous solutions at constant ionic strength (I=0.2mol dm(-3) KNO3) at pH 6.0 and various temperatures between 292 and 315K. PMID:17573236

Boghaei, Davar M; Askarizadeh, Elham; Bezaatpour, Abolfazl

2007-05-13

401

Synthesis, spectroscopic characterization and biological evaluation studies of Schiff's base derived from naphthofuran-2-carbohydrazide with 8-formyl-7-hydroxy-4-methyl coumarin and its metal complexes  

NASA Astrophysics Data System (ADS)

Metal complexes of the type ML2, where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and L = Schiff's base derived from the condensation of naphthofuran-2-carbohydrazide with 8-formyl-7-hydroxy-4-methyl coumarin have been synthesized. The chelation of the complexes have been elucidated in the light of analytical, IR, UV-vis, 1H NMR, mass, ESR spectral data, thermal and magnetic studies. The measured molar conductance values indicate that, the complexes are non-electrolytic in nature. The redox behavior of one of the synthesized metal complexes was investigated by cyclic voltammetry. The Schiff's base and its metal complexes have been screened for their in vitro antibacterial and antifungal activities by MIC method. The DNA cleavage activities of all the complexes were studied by agarose gel electrophoresis method. In addition, the free ligand along with its complexes has been studied for their antioxidant activity.

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

2012-12-01

402

Synthesis, spectroscopic characterization and biological evaluation studies of Schiff's base derived from naphthofuran-2-carbohydrazide with 8-formyl-7-hydroxy-4-methyl coumarin and its metal complexes.  

PubMed

Metal complexes of the type ML(2), where M=Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and L=Schiff's base derived from the condensation of naphthofuran-2-carbohydrazide with 8-formyl-7-hydroxy-4-methyl coumarin have been synthesized. The chelation of the complexes have been elucidated in the light of analytical, IR, UV-vis, (1)H NMR, mass, ESR spectral data, thermal and magnetic studies. The measured molar conductance values indicate that, the complexes are non-electrolytic in nature. The redox behavior of one of the synthesized metal complexes was investigated by cyclic voltammetry. The Schiff's base and its metal complexes have been screened for their in vitro antibacterial and antifungal activities by MIC method. The DNA cleavage activities of all the complexes were studied by agarose gel electrophoresis method. In addition, the free ligand along with its complexes has been studied for their antioxidant activity. PMID:23041921

Halli, M B; Sumathi, R B; Kinni, Mallikarjun

2012-09-08

403

Zn(II), Ni(II), Cu(II) and Pb(II) complexes of tridentate asymmetrical Schiff base ligands: synthesis, characterization, properties and biological activity.  

PubMed

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, (1)H NMR, (13)C 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 ZnL(2)A has lower MIC values than ampicillin for P. aeruginosa ATCC 27853 strain. PMID:23274224

?ahin, Mustafa; Koçak, Nuriye; Erdenay, Damla; Arslan, U?ur

2012-11-15

404

Inhibition of copper corrosion by self-assembled films of new Schiff bases and their modification with alkanethiols in aqueous medium  

NASA Astrophysics Data System (ADS)

The inhibitive action of self-assembled films derived from two ligands Schiff bases, including N,N?-ethylen-bis (salicylidenimine) and N,N?-ortho-phenylen-bis (salicylidenimine) on copper surface has been studied by electrochemical techniques in chloride and acidic solutions. It was found that when the concentration of the inhibitors was increased the inhibition efficiency was increased, too. The results of the electrochemical studies have illustrated that the inhibition efficiency of S-o-ph-S is higher than S-E-S. Both the Schiff bases obeyed the Langmuir isotherm and thermodynamics calculations revealed that S-o-ph-S had larger adsorption constant and more negative free energy of adsorption with respect to S-E-S. When the films were modified by propanethiol and 1-dodecanethiol, the corrosion resistance of mixed films was significantly increased.

Ehteshamzade, M.; Shahrabi, T.; Hosseini, M. G.

2006-02-01

405

Copper(II) complexes of symmetrical and unsymmetrical tetradentate Schiff base ligands incorporating 1-benzoylacetone: Synthesis, crystal structures and electrochemical behavior  

Microsoft Academic Search

Three new copper(II) complexes [CuL1]2(ClO4)2 (1), [CuL2]ClO4 (2) and [CuL3] (3) with three Schiff base ligands [HL1=1-phenyl-3-{3-[(pyridin-2-ylmethylene)-amino]-propylimino}-butan-1-one, HL2=1-phenyl-3-[3-(1-pyridin-2-yl-ethylideneamino)-propylimino]-butan-1-one and H2L3=3-[3-(1-methyl-3-oxo-3-phenyl-propylideneamino)-propylimino]-1-phenyl-butan-1-one] have been synthesized and structurally characterized by X-ray crystallography. The mono-negative tetradentate asymmetric Schiff base ligands (L1)? and (L2)? are chelated in complexes 1 and 2 to form square planar copper(II) complexes. In complex 1, the two units are associated

Biswarup Sarkar; Gabriele Bocelli; Andrea Cantoni; Ashutosh Ghosh

2008-01-01

406

Synthesis Characterization and Biological Activity Study of New Schiff and Mannich Bases and Some Metal Complexes Derived from Isatin and Dithiooxamide  

PubMed Central

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).

Abdulghani, Ahlam J.; Abbas, Nada M.

2011-01-01

407

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)

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.

Khan, Noor-ul Hasan; Pandya, Nirali; Prathap, K. Jeya; Kureshy, Rukhsana Ilays; Abdi, Sayed Hasan Razi; Mishra, Sandhya; Bajaj, Hari Chandra

2011-10-01

408

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)

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.

?ahin, Mustafa; Koçak, Nuriye; Erdenay, Damla; Arslan, U?ur

2013-02-01

409

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)

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.

Sobha, S.; Mahalakshmi, R.; Raman, N.

410

Enantioselective catalytic epoxidation of nonfunctionalized prochiral olefins by dissymmetric chiral Schiff base complexes of Mn(III) and Ru(III) metal ions II  

Microsoft Academic Search

A series of new dissymmetric chiral Schiff base complexes has been obtained by a systematic condensation of (1S,2S)(+)-diaminocyclohexane and 3-acetyl-4-hydroxy-6-methyl-2-pyrone with salicylaldehyde, 5-chloro-, 5-methoxy-and 5-nitrosalicylaldehyde and by subsequent metallation with manganese and ruthenium. The characterization of the complexes 1–8 was accomplished by physico chemical studies viz. microanalysis, IR-, UVVIS-, and CD spectral studies, optical rotation, molar conductance measurements and cyclic

R. I. Kureshy; N. H. Khan; S. H. R. Abdi; P. Iyer; A. K. Bhatt

1997-01-01

411

Synthesis and Evaluation of 4Diethyl Amino Benzaldehyde Schiff Base Cationic Amphiphiles as Corrosion Inhibitors for Carbon Steel in Different Acidic Media  

Microsoft Academic Search

A novel series of cationic surfactants containing Schiff base groups were synthesized by condensation of fatty amines namely:\\u000a dodecyl, tetradecyl, hexadecyl and octadecyl amine and 4-diethyl aminobenzaldehyde. The chemical structures of these surfactants\\u000a were confirmed using elemental analysis, FTIR spectra, 1H-NMR and atomic absorption spectroscopy. Surface properties of the synthesized compounds were determined using surface tension\\u000a techniques. The results of

Nabel A. Negm; Mohamad F. Zaki; Mounir A. I. Salem

2009-01-01

412

Electrochemical synthesis of metal (II) complexes of Schiff base 2-tosylamino (2?-pyridyl)aniline: the crystal structure of bis-[2-tosylamino(2?-pyridyl)anilinato]cobalt(II)  

Microsoft Academic Search

Complexes of cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) with the anion of the Schiff base 2-tosylamino(2?-pyridyl)aniline (HL) have been prepared by using an electrochemical procedure. These compounds were characterized by elemental analysis, IR, UV and NMR spectroscopy, and in the case of [CoL2] by X-ray diffraction methods. In this compound the cobalt(II) atom is in a distorted tetrahedral environment, each

Jose A. Garcia-Vazquez; Jaime Romero; Maria L. Duran; Antonio Sousa; Alexander D. Garnovskii; Anatolii S. Burlov; Dimitrii A. Garnovskii

1998-01-01

413

Synthesis, Spectral and Electrochemical Studies of Co(II) and Zn(II) Complexes of a Novel Schiff base Derived from Pyridoxal  

Microsoft Academic Search

A novel Schiff-base, N ? (4-n-butyl)phenylpyridoxaldimine (Hbppyr), was prepared and structurally characterized on the basis of elemental analyses, and mass, NMR & IR spectral data. Hbppyr was found to coordinate through the azomethine nitrogen and phenolate oxygen in [M(bppyr)2(H2O)2].nH2O where M = Co and Zn; non-coordination through pyridine nitrogen was implied by the IR spectral data as well as by

Archana Prasad; Ch. Parameswara Rao; Swati Mohan; Angad Kumar Singh; Rajiv Prakash; T. R. Rao

2009-01-01

414

Inhibition of copper corrosion by self-assembled films of new Schiff bases and their modification with alkanethiols in aqueous medium  

Microsoft Academic Search

The inhibitive action of self-assembled films derived from two ligands Schiff bases, including N,N?-ethylen-bis (salicylidenimine) and N,N?-ortho-phenylen-bis (salicylidenimine) on copper surface has been studied by electrochemical techniques in chloride and acidic solutions. It was found that when the concentration of the inhibitors was increased the inhibition efficiency was increased, too. The results of the electrochemical studies have illustrated that the

M. Ehteshamzade; T. Shahrabi; M. G. Hosseini

2006-01-01

415

Photoassisted "gate-lock" fluorescence "turn-on" in a new Schiff base and coordination ability of E-Z isomers.  

PubMed

Rapid photoresponse (1.0-8.0 min) through fluorescence "turn-on" signaling displayed by a novel Schiff base (L) creating "gate lock" via intramolecular C-H···N interaction in photoisomerized product (L') has been described. Coordination chemistry of pre- and postirradiated species demonstrated a drastic change in the reactivity which has been supported by NMR, HRMS, UV-vis, emission, electrochemical, and complexation studies. PMID:22229832

Pandey, Rampal; Gupta, Rakesh Kumar; Li, Pei-Zhou; Xu, Qiang; Misra, Arvind; Pandey, Daya Shankar

2012-01-09

416

DNA cleavage,in vitro antimicrobial and electrochemical studies of Co(II), Ni(II), and Cu(II) complexes withm-substituted thiosemicarbazide Schiff bases  

Microsoft Academic Search

Co(II), Ni(II), and Cu(II) complexes, ML2 · 2H2O have been synthesized with Schiff bases derived from m-substituted thiosemicarbazides and 2-methoxy benzaldehyde. The complexes are soluble in DMF\\/DMSO and non-electrolytes. From analytical, spectral (IR, UV-Vis, ESR, and FAB-mass), magnetic and thermal studies octahedral geometry is proposed for the complexes. The redox behavior of the complexes was investigated using cyclic voltammetry. The

Sangamesh A. Patil; Vinod H. Naik; Ajaykumar D. Kulkarni; Udaykumar Kamble; Gangadhar B. Bagihalli; Prema S. Badami

2010-01-01

417

Synthesis, characterization, DNA cleavage and in vitro antimicrobial studies of La(III), Th(IV) and VO(IV) complexes with Schiff bases of coumarin derivatives  

Microsoft Academic Search

A series of La(III), Th(IV) and VO(IV) complexes have been synthesized with Schiff bases derived from 8-formyl-7-hydroxy-4-methylcoumarin and o-phenylenediamine\\/ethylenediamine. The structure of the complexes has been proposed in the light of analytical, spectral (IR, UV–vis, ESR and FAB-mass), Magnetic and thermal studies. The complexes are soluble in DMF and DMSO. The measured molar conductance values indicate that, the complexes are

Ajaykumar Kulkarni; Sangamesh A. Patil; Prema S. Badami

2009-01-01

418

Synthesis, structure and characterization of fac-[Re(CO) 3] + complexes derived from hydrazone Schiff bases: DFT–TDDFT investigation on electronic structures  

Microsoft Academic Search

The syntheses, structural and spectroscopic characterization of the complexes of general formula [ReL(CO)3Cl] bearing bifunctional hydrazone Schiff base ligand L are presented in this paper. The structure of one of the complexes is determined by X-ray crystallography. The solid-state structure of the compound is involved in a secondary interaction in lattice forming a supramolecular array. The gas phase geometry optimization

Sucharita Basak; Deepak Chopra; Kajal Krishna Rajak

2008-01-01

419

Synthesis, characteristic and theoretical investigation of the structure, electronic properties and second-order nonlinearity of salicylaldehyde Schiff base and their derivatives.  

PubMed

A series of asymmetric donor-acceptor substituted salen-type Schiff-bases have been synthesized and their structures, electronic properties and second order nonlinearities were investigated by DFT methods. In order to verify the stable of these Schiff-base derivates, the IR spectrum of these Schiff-base derivates were calculated, the result showed that these compounds are stable. The results of TD-DFT calculation indicate that the derivatives with the electron-donating group (CH3, OCH3 or N(C2H5)2) have a red shift absorption compared to derivatives with the electron-withdrawing group (NO2). The analysis of MOS indicates that the CN group has contribution to the LUMO orbital while the groups of OCH3, N(C2H5)2 and NO2 have contribution to the HOMO orbital. OCH3, N(C2H5)2 as electron rich groups, made the derivates have a larger first static hyperpolarizability. However, the compound (II) with a NO2 substituent, also has a large first static hyperpolarizability. This is probably because of the special transition model, namely the values of two oscillator strength f (fHOMO-1-LUMO=0.405, fHOMO-LUMO=0.321) are almost equal. In order to understand the influence of the energy gap (?E) between the HOMO and the LUMO orbitals on the first static hyperpolarizability, we calculated the energy gap (?E) of all Schiff-base compounds. The results show that the smaller the HOMO-LUMO energy gap is, the larger the first static hyperpolarizability is. PMID:21159548

Tang, Guo-Dong; Zhao, Jian-Ying; Li, Rong-Qing; Yuan-Cao; Zhang, Zai-Chao

2010-11-23

420

Zeolite-encapsulated and clay-intercalated metal porphyrin, phthalocyanine and Schiff-base complexes as models for biomimetic oxidation catalysts: an overview  

Microsoft Academic Search

This paper reviews some important recent work on the design and characterization of zeolite-encapsulated and clay-intercalated metal-Schiff base, -porphyrin and-phthalocyanine complexes. After an introduction to the chemistry of clays and zeolites, the incorporation methods of these complexes within the mineral materials are discussed and an overview of their physicochemical characterization is reported. A large part of this paper is devoted

Fethi Bedioui

1995-01-01

421

The synthesis of (N 2O 2S 2)-Schiff base ligands and investigation of their ion extraction capability from aqueous media  

NASA Astrophysics Data System (ADS)

Two new Schiff bases (I) and (II) containing nitrogen-sulfur-oxygen donor atoms were designed and synthesized in a multi-step reaction sequence. The Schiff base (I) was used in solvent extraction of metal chlorides such as Cu 2+ and Cr 3+ as well as metal picrates such as Hg 2+ and UO 22+ from aqueous phase to the organic phase. The influences of the parameter functions, such as pH, solvent, ionic strength of aqueous phase, aqueous to organic phase and concentration of the extractant were investigated to shed light on their chemical extracting properties upon the extractability of metal ions. The effect of chloroform, dichloromethane and nitrobenzene as organic solvents over the metal chlorides extraction was investigated at 25 ± 0.1 °C by using flame atomic absorption and the result is that the ability of extraction in solvents as follows: C 6H 5NO 2 > CHCl 3 > CH 2Cl 2 and the compositions of the extracted species have been determined. The metal picrate extraction was investigated at 25 ± 0.1 °C by using UV-visible spectrometry. As well that the extraction of picrates metal such as UO 22+ and Hg 2+ with Schiff base(I) in absence and presence of 2-(2-aminoethyl) pyridine was investigated in chloroform. The extraction results revealed the presence of neutral donors 2-(2-aminoethyl) pyridine shifts the extraction percentage curves towards higher pH region, indicating a synergistic effect of this donors on extraction of UO 22+ and Hg 2+ by the studied Schiff base (I).

Zoubi, Wail A. L.; Kandil, Farouk; Chebani, Mohamad Khaled

2011-09-01

422

Threonine-89 participates in the active site of bacteriorhodopsin: evidence for a role in color regulation and Schiff base proton transfer.  

PubMed

Bacteriorhodopsin (bR) functions as a light-driven proton pump in the purple membrane of Halobacterium salinarium. A major feature of bR is the existence of an active site which includes a retinylidene Schiff base and amino acid residues Asp-85, Asp-212, and Arg-82. This active site participates in proton transfers and regulates the visible absorption of bacteriorhodopsin and its photointermediates. In this work we find evidence that Thr-89 also participates in this active site. The substitution Thr-89 --> Asn (T89N) results in changes in the properties of the all-trans retinylidene chromophore of light-adapted bR including a redshift of the visible lambda(max) and a downshift in C=N and C=C stretch frequencies. Changes are also found in the M and N intermediates of the T89N photocycle including shifts in lambda(max), a downshift of the Asp-85 carboxylic acid C=O stretch frequency by 10 cm(-1), and a 3-5-fold decrease in the rate of formation of the M intermediate. In contrast, the properties of the 13-cis retinylidene chromophore of dark-adapted T89N as well as the K and L intermediates of the T89N photocycle are similar to the wild-type bacteriorhodopsin. These results are consistent with an interaction of the hydroxyl group of Thr-89 with the protonated Schiff base of light-adapted bR and possibly the N intermediate but not the 13-cis chromophore of dark-adapted bR or the K and L intermediates. Thr-89 also appears to influence the rate of Schiff base proton transfer to Asp-85 during formation of the M intermediate, possibly through an interaction with Asp-85. In contrast, the hydroxyl group of Thr-89 is not obligatory for proton transfer from Asp-96 to the Schiff base during formation of the N intermediate. PMID:9200698

Russell, T S; Coleman, M; Rath, P; Nilsson, A; Rothschild, K J

1997-06-17

423

Synthesis, Characterization and Biological Studies of Zn(II) Complex of Schiff Base Derived from 5-Acetazolamido-1,3,4 - Thiadiazole-2- Sulphonamide, A Diuretic Drug  

Microsoft Academic Search

acetazolamido-1,3,4-thiadiazole-2-sulphonamide, trade name acetazolamide, is a diuretic drug (Diuretic drugs increase the output of urine through kidneys). In the present communication, the metal complex of Zn(II) with schiff base derived from salicyladehyde and 5-acetazolamide -1,3,4 - thiadiazole-2-sulphonamide have been synthesized keeping in view that some metal complexes are found to be more potent than their parent drugs. These complexes were

Suparna Ghosh; Suman Malik; Bharti Jain; N. Ganesh

2009-01-01

424

Silica Gel Coated with Schiff's Base: Synthesis and Application as an Adsorbent for Cadmium, Copper, Zinc, and Nickel Determination after Preconcentration by Flame Atomic Absorption Spectrometry  

Microsoft Academic Search

A method for the preconcentration of Cd(II), Cu(II), Zn(II), and Ni(II) is proposed using a minicolumn filled with silica gel modified by Schiff's base. The retained analytes on the ligand-coated silica gel were recovered with a small volume of HNO3 (nitric acid). The metal ions in the eluent were determined by flame atomic absorption spectrometer (FAAS). Different factors, including the

Farzaneh. Shemirani; Aazam Alsadat. Mirroshandel; Masood. Salavati Niasari; Reyhaneh Rahnama Kozani

2004-01-01

425

Studies on a series complexes of copper (II), zinc (II), cobalt (III) with Schiff base derived from d -glucosamine and salicylaldehyde  

Microsoft Academic Search

Copper (II) zinc (II) cobalt (III) complexes with the Schiff base derived from salicylaldehyde andd-glucosamine were synthesized. These compounds abbreviated as SG, CuSG, ZnSG, CoSG were characterized by elemental analyses,\\u000a IR, UV-Vis,1H NMR and MS spectrum. ESR spectrum, magnetic susceptibility measured by Evans method for CuSG had also been done. It is suggested\\u000a that the complexes in solution have pseudotetrahedral

Ye Yong; Hu Jiming; Feng Changjian; Zeng Yun'e

1997-01-01

426

Synthesis, spectral characterization, and antimicrobial studies of metal complexes of the Schiff base derived from [4-amino-N-guanylbenzene sulfonamide] and salicylaldehyde  

Microsoft Academic Search

Sulfaguanidinesalicylaldimine is a good bacteriostatic and a good complexing agent. Schiff-base complexes of Cu(II), Ni(II), Co(II), Zn(II), Cd(II), VO(IV), and UO2(VI) have been synthesized. The structural features of the complexes have been confirmed by microanalytical data, FAB mass, IR, UV-Vis, H-NMR, and EPR spectra. Molar conductance indicates the presence of nonelectrolytes. Spectroscopic and other analytical studies reveal the square-planar geometry

C. D. Sheela; C. Anitha; P. Tharmaraj; D. Kodimunthri

2010-01-01

427

Studies on some salicylaldehyde Schiff base derivatives and their complexes with Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II)  

Microsoft Academic Search

The formation constants of some transition metal ions Cr(III), Mn(II), Fe(III), Ni(II) and Cu(II) binary complexes containing Schiff bases resulting from condensation of salicylaldehyde with aniline (I), 2-aminopyridine (II), 4-aminopyridine (III) and 2-aminopyrimidine (IV) were determined pH-metrically in ethanolic medium (80%, v\\/v). The formation constants were determined for all binary complexes. The important infrared (IR) spectral bands corresponding to the

S. A. Abdel-Latif; H. B. Hassib; Y. M. Issa

2007-01-01

428

Accommodation of Mn II, Mn III–N, O, O, O-donor Schiff base complexes in zeolite-Y: Synthesis, structural studies and CO adsorption  

Microsoft Academic Search

Manganese (II)-, (III)-complexes with NO3 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

Ayman H. Ahmed; Zeinhom M. El-Bahy; Tarek M. Salama

2010-01-01

429

Synthesis, spectral characterization, catalytic and antibacterial studies of new Ru(III) Schiff base complexes containing chloride/bromide and triphenylphosphine/arsine as co-ligands.  

PubMed

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, (1)H, (13)C 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. PMID:19679508

Arunachalam, S; Padma Priya, N; Jayabalakrishnan, C; Chinnusamy, V

2009-07-16

430

Synthesis and characterization of an azo dibenzoic acid Schiff base and its Ni(II), Pb(II), Zn(II) and Cd(II) complexes.  

PubMed

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

Kakanejadifard, Ali; Esna-ashari, Fatemeh; Hashemi, Payman; Zabardasti, Abedin

2013-01-05

431

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)

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.

Keskio?lu, Eren; Gündüzalp, Ayla Balaban; Çete, Servet; Hamurcu, Fatma; Erk, Birgül

2008-08-01

432

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)

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 13? NMR spectroscopy.

Kakanejadifard, Ali; Esna-ashari, Fatemeh; Hashemi, Payman; Zabardasti, Abedin

2013-04-01

433

Surface Tectonics of Nanoporous Networks of Melamine-Capped Molecular Building Blocks formed through Interface Schiff-Base Reactions.  

PubMed

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

Liu, Xuan-He; Wang, Dong; Wan, Li-Jun

2013-07-18

434

Base sequence effects on interactions of aromatic mutagens with DNA  

SciTech Connect

The chemical binding of bulky, mutagenic and carcinogenic polynuclear aromatic compounds to certain base-sequences in genomic DNA is known to inhibit DNA replication, and to induce mutations and cancer. In particular, sequences that contain multiple consecutive guanines appear to be hot spots of mutation. The objectives of this research are to determine how the base sequence around the mutagen-modified target bases influences the local DNA conformation and gives rise to mispairing of bases, or deletions, near the lesion. Oligonucleotides containing one, two, or three guanines were synthesized and chemically reacted with the mutagen anti-7,8-dihydroxy-9,10-epoxy-benzo(a)pyrene (BPDE), one of the most mutagenic and tumorigenic metabolites of benzo(a)pyrene. Adducts are formed in which only one of the guanines is modified by trans or cis addition to the exocyclic amino group. The BPDE-oligonucleotides are separated chromatographically, and the site of modification is established by Maxam-Gilbert high resolution gel electrophoresis techniques. The thermodynamic properties of duplexes using complementary, or partially complementary strands were examined. In the latter, the base opposite the modified guanine was varied in order to investigate the probability of mispairing of the modified G with A,T and G. The successful synthesis of stereospecific and site-specific mutagen-oligonucleotide adducts opens new possibilities for correlating adduct structure-biological activity relationships, and thus lead to a better understanding of base-sequence effects in mutagenesis induced by energy-related bulky polynuclear aromatic chemicals.

Geacintov, N.E.

1992-09-30

435

Aromatic-aromatic interactions in structures of proteins and protein-DNA complexes: a study based on orientation and distance  

PubMed Central

Interactions between the aromatic amino acid residues have a significant influence on the protein structures and protein-DNA complexes. These interactions individually provide little stability to the structure; however, together they contribute significantly to the conformational stability of the protein structure. In this study, we focus on the four aromatic amino acid residues and their interactions with one another and their individual interactions with the four nucleotide bases. These are analyzed in order to determine the extent to which their orientation and the number of interactions contribute to the protein and protein-DNA complex structures.

Anjana, Ramnath; Vaishnavi, Marthandan Kirti; Sherlin, Durairaj; Kumar, Surapaneni Pavan; Naveen, Kora; Kanth, Pasam Sandeep; Sekar, Kanagaraj

2012-01-01

436

Synthesis, structural characterization, fluorescence, antimicrobial, antioxidant and DNA cleavage studies of Cu(II) complexes of formyl chromone Schiff bases.  

PubMed

Cu(II) complexes have been synthesized from different Schiff bases, such as 3-((2-hydroxy phenylimino)methyl)-4H-chromen-4-one (HL(1)), 2-((4-oxo-4H-chromen-3-yl)methylneamino) benzoicacid (HL(2)), 3-((3-hydroxypyridin-2-ylimino)methyl)-4H-chromen-4-one (HL(3)) and 3-((2-mercaptophenylimino)methyl)-4H-chromen-4-one (HL(4)). 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. PMID:23220531

Kavitha, P; Saritha, M; Laxma Reddy, K

2012-11-01

437

Synthesis, spectral, antitumor and antimicrobial studies on Cu(II) complexes of purine and triazole Schiff base derivatives  

NASA Astrophysics Data System (ADS)

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 ?-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 ?g/ml against MCF7, HCT116 and HEPG2, respectively.

Amer, Said; El-Wakiel, Nadia; El-Ghamry, Hoda

2013-10-01

438

Environmental Dependence of Artifact CD Peaks of Chiral Schiff Base 3d-4f Complexes in Soft Mater PMMA Matrix  

PubMed Central

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.

Okamoto, Yu; Nidaira, Keisuke; Akitsu, Takashiro

2011-01-01

439

Synthesis, antiproliferative activity and genotoxicity of novel anthracene-containing aminophosphonates and a new anthracene-derived Schiff base.  

PubMed

A new Schiff base, 9-anthrylidene-furfurylamine and three novel anthracene-containing ?-aminophosphonates, [N-methyl(dimethoxyphosphonyl)-1-(9-anthryl)]-p-toluidine, [N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]-p-toluidine and [N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]furfurylamine were synthesized. The compounds have been characterized by elemental analysis, TLC, IR, NMR and fluorescent spectra. The aminophosphonates and their synthetic precursors were tested for in vitro antitumor activity on a panel of seven human epithelial cancer cell lines. Safety testing was performed both in vitro (3T3 NRU test) and in vivo on ICR mice for genotoxicity and antiproliferative activity. 9-Anthrylidene-furfurylamine and [N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]furfurylamine were most potent cytotoxic agents towards colon carcinoma cell line HT-29. The latter compound exhibited also antiproliferative activity to HBL-100, MDA-MB-231 and 647-V cells. The aminophosphonate [N-methyl(dimethoxyphosphonyl)-1-(9-anthryl)]-p-toluidine and its synthetic precursor 9-anthrylidene-p-toluidine were found to be cytotoxic to HBL-100 and HT-29 tumor cell lines, respectively. Moderate genotoxic and antiproliferative activity in vivo and low toxicity to Balb/c 3T3 (clone 31) mouse embryo cells were observed for all tested compounds. The subcellular distribution of two tested compounds in a tumor cell culture system was also studied. PMID:22142614

Kraicheva, I; Tsacheva, I; Vodenicharova, E; Tashev, E; Tosheva, T; Kril, A; Topashka-Ancheva, M; Iliev, I; Gerasimova, Ts; Troev, K

2011-11-20

440

A novel bioactive tyramine derived Schiff base and its transition metal complexes as selective DNA binding agents.  

PubMed

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, ML2Cl2 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 AH2 (ascorbic acid). The complexes showed enhanced antifungal and antibacterial activities compared to the free ligand. PMID:21215688

Raman, N; Sobha, S; Thamaraichelvan, A

2010-12-22

441

Synthesis, structural characterization, catalytic, thermal and electrochemical investigations of bidentate Schiff base ligand and its metal complexes.  

PubMed

In this study, we prepared the Schiff base ligand (L) and its Cu(II), Co(II) and Ni(II) complexes. The compounds were characterized by the analytical and spectroscopic methods. The ligand (L) behaves as a bidentate ligand and coordinates to the metal ions via the nitrogen atoms. The complexes have the mononuclear structures. The analytical and spectroscopic results indicated that the chloride ions coordinate to the metal ions. The complexes have the general formulae [M(L)(Cl)(2)] (M: Cu(II), Co(II) and Ni(II) metal ions). Electrochemical properties were investigated as ligand and metal centres in the different solvents and at the scan rates, respectively. The thermal properties of the metal complexes were studied in the N(2) atmosphere. We investigated the improved catalytic activity of the Cu(II), Co(II) and Ni(II) complexes on the cyclohexane as a substrate. Obtained data showed that the best catalyst is the Cu(II) complex. The single crystal of the ligand (L) was obtained from CH(3)CN solution. There is a C-H...N H-bond linking the molecules into chains (C6)...N(2) 3.4415(18)A under symmetry operation (x+1,y,z) as well as pi-pi stacking on the outside of the "V" shape--nothing on the inside. PMID:20409747

Dolaz, Mustafa; McKee, Vickie; Uru?, Serhan; Demir, Necmettin; Sabik, Ali E; Gölcü, Ay?egül; Tümer, Mehmet

2010-03-18

442

Trace analysis of cefotaxime at carbon paste electrode modified with novel Schiff base Zn(II) complex.  

PubMed

Cefotaxime a third generation cephalosporin drug estimation in nanomolar concentration range is demonstrated for the first time in aqueous and human blood samples using novel Schiff base octahedral Zn(II) complex. The cefotaxime electrochemistry is studied over graphite paste and Zn(II) complex modified graphite paste capillary electrodes in H(2)SO(4) (pH 2.3) using cyclic voltammetry and differential pulse voltammetry. Cefotaxime enrichment is observed over Zn(II) complex modified graphite paste electrode probably due to interaction of functional groups of cefotaxime with Zn(II) complex. Possible interactions between metal complex and cefotaxime drug is examined by UV-vis and electrochemical quartz crystal microbalance (EQCM) techniques and further supported by voltammetric analysis. Differential pulse voltammetry (DPV) with modified electrode is applied for the determination of cefotaxime in acidified aqueous and blood samples. Cefotaxime estimation is successfully demonstrated in the range of 1-500 nM for aqueous samples and 0.1-100 microM in human blood samples. Reproducibility, accuracy and repeatability of the method are checked by triplicate reading for large number of samples. The variation in the measurements is obtained less than 10% without any interference of electrolyte or blood constituents. PMID:19084660

Nigam, Preeti; Mohan, Swati; Kundu, Subir; Prakash, Rajiv

2008-09-25

443

Synthesis, spectroscopic, structural characterization, electrochemical and antimicrobial activity studies of the Schiff base ligand and its transition metal complexes.  

PubMed

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 (1)H((13)C) 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 mVs(-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-Hcdots, three dots, centeredCl 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. PMID:19646919

Aslanta?, Mehmet; Kendi, Engin; Demir, Necmettin; Sabik, Ali E; Tümer, Mehmet; Kertmen, Metin

2009-07-15

444

Synthesis, antimicrobial, DNA-binding and photonuclease studies of Cobalt(III) and Nickel(II) Schiff base complexes  

NASA Astrophysics Data System (ADS)

New metal complexes of the type [M(nih)(L)](PF6)n·xH2O and [M(nih)2](PF6)·xH2O (where M = Co(III) or Ni(II), L = 1,10-phenanthroline (phen)/or 2,2' bipyridine (bpy), nih = 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone, n = 2 or 1 and x = 3 or 2) have been synthesized and characterized by elemental analysis, magnetic, IR and 1H NMR spectral data. The electronic and magnetic moment 2.97-3.07 B.M. data infers octahedral geometry for all the complexes. The IR data reveals that Schiff base (nih) form coordination bond with the metal ion through azomethine-nitrogen, phenolic-oxygen and carbonyl-oxygen in a tridentate fashion. In addition, DNA-binding properties of these six metal complexes were investigated using absorption spectroscopy, viscosity measurements and thermal denaturation methods. The results indicated that the nickel(II) complex strongly bind with calf-thymus DNA with intrinsic DNA binding constant Kb value of 4.9 × 104 M-1 for (3), 4.2 × 104 M-1 for (4), presumably via an intercalation mechanism compared to cobalt(III) complex with Kb value of 4.6 × 104 M-1 (1) and 4.1 × 104 M-1 (2). The DNA Photoclevage experiment shows that, the complexes act as effective DNA cleavage agent.

Sangeetha Gowda, K. R.; Bhojya Naik, H. S.; Vinay Kumar, B.; Sudhamani, C. N.; Sudeep, H. V.; Ravikumar Naik, T. R.; Krishnamurthy, G.

2013-03-01

445

Potential bioactive Schiff base compounds: Synthesis, characterization, X-ray structures, biological screenings and interaction with Salmon sperm DNA.  

PubMed

Three Schiff base compounds ofN'-substituted benzohydrazide and sulfonohydrazide derivatives: N'-(2-hydroxy-3-methoxybenzylidene)-4-tert-butyl- benzohydrazide (1), N'-(5-bromo-2-hydroxybenzylidene)-4-tert-butylbenzohydrazide (2) and N'-(2-hydroxy-3-methoxybenzylidene)-4-methylbenzenesulfonohydrazide (3) were synthesized and characterized by elemental analysis, FT-IR, (1)H, (13)C NMR spectroscopy and single crystal analysis. The title compounds have been screened for their biological activities including, antibacterial, antifungal, antioxidant, cytotoxic, enzymatic activities as well as interaction with SS-DNA which showed remarkable activities in each area of research. The DNA binding of the compounds 1-3 with SS-DNA has been carried out with absorption spectroscopy, which reveals the binding propensity towards SS-DNA via intercalation mode of interaction. The intercalative mode of interaction is also supported by viscometric results. The synthesized compounds were also found to be effective against alkaline phosphatase enzyme. They also show significant to good antimicrobial activity against six bacterial and five fungal strains. The MIC (minimum inhibitory concentration) for antibacterial activity ranges from 1.95-500?g/mL. Compounds 1-3 show cytotoxic activity comparable to the control. At higher conc. (100?g/L) compound 3 shows 100% activity means that it has killed all brine shrimps. They were also found to be effective antioxidant of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and show almost comparable antioxidant activity to that of the standard and known antioxidant, ascorbic acid. PMID:23912178

Sirajuddin, Muhammad; Uddin, Noor; Ali, Saqib; Tahir, Muhammad Nawaz

2013-07-16

446

Potential bioactive Schiff base compounds: Synthesis, characterization, X-ray structures, biological screenings and interaction with Salmon sperm DNA  

NASA Astrophysics Data System (ADS)

Three Schiff base compounds ofN'-substituted benzohydrazide and sulfonohydrazide derivatives: N'-(2-hydroxy-3-methoxybenzylidene)-4-tert-butyl- benzohydrazide (1), N'-(5-bromo-2-hydroxybenzylidene)-4-tert-butylbenzohydrazide (2) and N'-(2-hydroxy-3-methoxybenzylidene)-4-methylbenzenesulfonohydrazide (3) were synthesized and characterized by elemental analysis, FT-IR, 1H, 13C NMR spectroscopy and single crystal anal