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1

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

2

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

3

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

4

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

5

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

6

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

7

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

8

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

9

Synthesis, spectral characterization, DNA binding ability and antibacterial screening of copper(II) complexes of symmetrical NOON tetradentate Schiff bases bearing different bridges  

NASA Astrophysics Data System (ADS)

A novel series of four copper(II) complexes were synthesized by thermal reaction of copper acetate salt with symmetrical tetradentate Schiff bases, N,N?bis(o-vanillin)4,5-dimethyl-l,2-phenylenediamine (H2L1), N,N?bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L2), N,N?bis(o-vanillin)4,5-dichloro-1,2-phenylenediamine (H2L3) and N,N?bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L4), respectively. All the new synthesized complexes were characterized by using of microanalysis, FT-IR, UV-Vis, magnetic measurements, ESR, and conductance measurements, respectively. The data revealed that all the Schiff bases (H2L1-4) coordinate in their deprotonated forms and behave as tetradentate NOON coordinated ligands. Moreover, their copper(II) complexes have square planar geometry with general formula [CuL1-4]. The binding of the complexes with calf thymus DNA (CT-DNA) was investigated by UV-Vis spectrophotometry, fluorescence quenching and viscosity measurements. The results indicated that the complexes bind to CT-DNA through an intercalative mode. From the biological activity view, the copper(II) complexes and their parent ligands were screened for their in vitro antibacterial activity against the bacterial species Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosai by well diffusion method. The complexes showed an increased activity in comparison to some standard drugs.

Bahaffi, Saleh O.; Abdel Aziz, Ayman A.; El-Naggar, Maher M.

2012-08-01

10

Synthesis, structural characterization, antiradical and antidiabetic activities of copper(II) and zinc(II) Schiff base complexes derived from salicylaldehyde and ?-alanine  

Microsoft Academic Search

A series of copper(II) and zinc(II) complexes involving a tridentate O,N,O’-donor Schiff base derived from salicylaldehyde and ?-alanine {i.e. N-salicylidene-?-alanine(2-), (L)}, having the composition [Cu2(L)2(H2O)]·H2O (1), [Cu(L)(H2O)]n (2), and [Zn(L)(H2O)]n (3), have been prepared and characterized by elemental analyses, UV–visible (UV–VIS), FT-IR and ESI-MS spectra, and thermal analyses. Complexes 1 and 2 have been investigated by single crystal X-ray analysis

Ján Van?o; Jaromír Marek; Zden?k Trávní?ek; Eva Ra?anská; Jan Muselík; Ol’ga Švajlenová

2008-01-01

11

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

12

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

13

Nanodimensional microreactors encapsulation of 15- and 16-membered diaza dioxa macrocyclic Schiff-base copper(II) complex nanoparticles: Synthesis and characterization  

Microsoft Academic Search

Copper(II) complexes with 15- and 16-membered diaza dioxa Schiff-base macrocyclic ligands “[Cu(R[15 or 16]N2O2)]2+ (R=Et, Pr, Ph, Ch)” were entrapped in the nanopores of zeolite-Y by a three-step process in the liquid phase: (i) exchange of Cu(II) ions with NaY in water solution, (ii) reaction of Cu(II)–NaY with excess 1,3-bis(2-carboxyaldehydephenoxy)propane (O2O2) in methanol, [(1,3-bis(2-carboxyaldehydephenoxy)propane)copper]2+@NaY, [Cu(O2O2)]2+@NaY (iii) template synthesis of [Cu(O2O2)]2+@NaY

Masoud Salavati-Niasari

2010-01-01

14

The interaction of taurine-salicylaldehyde Schiff base copper(II) complex with DNA and the determination of DNA using the complex as a fluorescence probe.  

PubMed

The interaction of taurine-salicylaldehyde Schiff base copper(II) (Cu(TSSB)2(2+)) complex with DNA was explored by using UV-vis, fluorescence spectrophotometry, and voltammetry. In pH 7.4 Tris-HCl buffer solution, the binding constant of the Cu(TSSB)2(2+) complex interaction with DNA was 3.49 x 10(4) L mol(-1). Moreover, due to the fluorescence enhancing of Cu(TSSB)2(2+) complex in the presence of DNA, a method for determination of DNA with Cu(TSSB)2(2+) complex as a fluorescence probe was developed. The fluorescence spectra indicated that the maximum excitation and emission wavelength were 389 nm and 512 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range of 0.03-9.03 microg mL(-1) for calf thymus DNA (CT-DNA), 0.10-36 microg mL(-1) for yeast DNA and 0.01-10.01 microg mL(-1) for salmon DNA (SM-DNA), respectively. The corresponding detection limits are 7 ng mL(-1) for CT-DNA, 3 ng mL(-1) for yeast DNA and 3 ng mL(-1) for SM-DNA. Using this method, DNA in synthetic samples was determined with satisfactory results. PMID:20627676

Zhang, Xiaoyan; Wang, Yong; Zhang, Qianru; Yang, Zhousheng

2010-09-15

15

The interaction of taurine-salicylaldehyde Schiff base copper(II) complex with DNA and the determination of DNA using the complex as a fluorescence probe  

NASA Astrophysics Data System (ADS)

The interaction of taurine-salicylaldehyde Schiff base copper(II) (Cu(TSSB) 22+) complex with DNA was explored by using UV-vis, fluorescence spectrophotometry, and voltammetry. In pH 7.4 Tris-HCl buffer solution, the binding constant of the Cu(TSSB) 22+ complex interaction with DNA was 3.49 × 10 4 L mol -1. Moreover, due to the fluorescence enhancing of Cu(TSSB) 22+ complex in the presence of DNA, a method for determination of DNA with Cu(TSSB) 22+ complex as a fluorescence probe was developed. The fluorescence spectra indicated that the maximum excitation and emission wavelength were 389 nm and 512 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range of 0.03-9.03 ?g mL -1 for calf thymus DNA (CT-DNA), 0.10-36 ?g mL -1 for yeast DNA and 0.01-10.01 ?g mL -1 for salmon DNA (SM-DNA), respectively. The corresponding detection limits are 7 ng mL -1 for CT-DNA, 3 ng mL -1 for yeast DNA and 3 ng mL -1 for SM-DNA. Using this method, DNA in synthetic samples was determined with satisfactory results.

Zhang, Xiaoyan; Wang, Yong; Zhang, Qianru; Yang, Zhousheng

2010-09-01

16

Synthesis, characterization and DNA interaction of new copper(II) complexes of Schiff base-aroylhydrazones bearing naphthalene ring.  

PubMed

Two new copper(II) complexes with the condensation products of methyl 2-naphthyl ketone with 4-hydroxybenzohydrazide, 4-hydroxy-N'-[(1Z)-1-(naphthalen-2-yl)ethylidene]benzohydrazide [HL(1)] and (Z)-ethyl 2-(4-(2-(1-(naphthalen-2-yl)ethylidene)hydrazinecarbonyl)phenoxy)acetate (HL(2)) were synthesized and characterized by elemental analysis, infrared spectra, UV-Vis electronic absorption spectra, magnetic susceptibility measurements, TGA, powder XRD and SEM-EDS. The binding properties of the copper(II) complexes with calf thymus DNA were studied by using the absorption titration method. DNA cleavage activities of the synthesized copper complexes were examined by using agarose gel electrophoresis. The effect of complex concentration on the DNA cleavage reactions in the absence and presence of H2O2 was also investigated. The experimental results suggest that the copper complexes bind significantly to calf thymus DNA by both groove binding and intercalation modes and cleavage effectively pBR322 DNA. The mechanistic studies demonstrate that a hydrogen peroxide-derived species and singlet oxygen ((1)O2) are the active oxidative species for DNA cleavage. PMID:23562627

Gökçe, Cansu; Gup, Ramazan

2013-03-14

17

Synthesis, characterization, and tyrosinase biomimetic catalytic activity of copper(II) complexes with schiff base ligands derived from ?-diketones with 2-methyl-3-amino-(3H)-quinazolin-4-one  

NASA Astrophysics Data System (ADS)

A template condensation of ?-diketones (biacetyl, benzile and 2,3-pentanedione) with 2-methyl-3-amino-(3H)-quinazolin-4-one (AMQ) in the presence of CuX2 (X = Cl-, Br-, NO3- or ClO4-) resulted in the formation of tetradentate Schiff base copper(II) complexes of the type [CuLX]X and [CuL]X2. Structural characterization of the complex species was achieved by several physicochemical methods, namely elemental analysis, electronic spectra, IR, ESR, molar conductivity, thermal analysis (TAG & DTG), and magnetic moment measurements. The stereochemistry, the nature of the metal chelates, and the catalytic reactivity are markedly dependent upon the type of counter anions and the ligand substituent within the carbonyl moiety. A square planar monomeric structure is proposed for the perchlorate, nitrate, and bromide complexes, in which the counter anions are loosely bonded to copper(II) ion. For the chloride complexes, the molar conductivities and the spectral data indicated that they have square-pyramidal environments around copper(II) center. The reported copper(II) complexes exhibit promising tyrosinase catalytic activity towards the hydroxylation of phenol followed by the aerobic oxidation of the resulting catechol. A linear correlation almost exists between the catalytic reactivity and the Lewis-acidity of the central copper(II) ion created by the donating properties of the parent ligand. The steric considerations could be accounted to clarify the difference in the catalytic activity of these functional models.

Ramadan, Abd El-Motaleb M.; Ibrahim, Mohamed M.; Shaban, Shaban Y.

2011-12-01

18

An antiferromagnetically coupled hexanuclear copper(II) Schiff base complex containing phenoxo and dicyanamido bridges: Structural aspects and magnetic properties  

Microsoft Academic Search

A novel hexanuclear complex [{(CuL)2Cu}2(?-dca)2](ClO4)2·2L?(1) (where H2L=(OH)C6H4C(CH3)N(CH2)3NC(CH3)C6H4(OH) or N,N?-bis(2-hydroxyacetophenone) propylenediimine and dca=N(CN)2? and L?=2-hydroxyacetophenone) has been synthesized and characterized by elemental analysis, UV–Vis, FT-IR spectroscopic and electrochemical methods. Single crystal X-ray structural characterization reveals a centrosymmetric nature of the complex unit, where the metal centers adopt distorted square-planar and distorted octahedral geometries. Structural analysis also reveals ?2-phenoxo bridges between terminal

Pritha Talukder; Shyamapada Shit; Ashok Sasmal; Stuart R. Batten; Boujemaa Moubaraki; Keith S. Murray; Samiran Mitra

2011-01-01

19

Syntheses, structural properties and catecholase activity of copper(II) complexes with reduced Schiff base N-(2-hydroxybenzyl)-amino acids.  

PubMed

A number of dicopper(II) complexes of reduced Schiff base ligands, N-(2-hydroxybenzyl)-amino acids [Cu2L2(H2O)x].yH2O (L = Sgly (1), D-Sala (2), L-Sala (3), DL-Sala (4), Sab2 (5), Sbal (6), Sab4 (7), Sval (8), Shis (9), Styr (10) and Stryp (11), x= 0-2 & y= 0-2) have been synthesized, and the solid-state structures of, and have been determined. The compounds and are binuclear in which the Cu(II) centres have square-pyramidal geometry with apical sites occupied by aqua ligands. In and one axial site is occupied by water and the other by an oxygen atom of the carboxylate group from the adjacent dimer through oxygen atoms to form 1D helical polymer. Variable temperature magnetic measurements of the dimer and helical polymer showed that they are typical for moderately strong antiferromagnetic coupling. All the complexes show significant catalytic activity on the oxidation of 3,5-di-tert-butylcatechol. The activity measured in terms of Kcat in the range 199-3800 h(-1) has been found to follow the order: 7>6>8>3>5 approximately 2 approximately 1>4 >10 >9 >11. The catalytic activity is found to increase with increasing the length of the methylene side chain of the amino acid in the reduced Schiff base ligands. PMID:15356749

Yang, Chang-Tong; Vetrichelvan, Muthalagu; Yang, Xiandong; Moubaraki, Boujemaa; Murray, Keith S; Vittal, Jagadese J

2003-12-01

20

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

21

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

22

Synthesis, spectral characterization and biological evaluation of copper(II) and nickel(II) complexes with thiosemicarbazones derived from a bidentate Schiff base  

NASA Astrophysics Data System (ADS)

Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized with the ligand 1-Tetralone thiosemicarbazone (where L = 1-Tetralone thiosemicarbazone and X=Cl,1/2SO42-). The molar conductance of the complexes in fresh solution of DMSO lies in the range of 10-20 ?-1 cm2 mol-1 indicating their non-electrolytic behavior. Thus, the complexes may be formulated as [M(L2)X2]. Ligand was characterized by mass, NMR, IR and single crystallographic studies. All the complexes were characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. The IR spectral data of ligand indicated the involvement of sulfur and azomethine nitrogen in coordination to the central metal ion. The copper(II) and nickel(II) complexes were found to have magnetic moments1.93-1.96 BM and 2.91-2.94 BM corresponding to one and two unpaired electrons respectively. On the basis of molar conductance, EPR, electronic and infrared spectral studies, a tetragonal geometry has been assigned for Cu(II) chloride complex and trigonal bipyramidal to Cu(II) sulfate complex but an octahedral geometry for Ni(II) complexes. Newly synthesized ligand and its Cu(II) and Ni(II) complexes have also been screened against different bacterial and fungal species.

Chandra, Sulekh; Bargujar, Savita; Nirwal, Rita; Yadav, Neesha

2013-04-01

23

Rare example of mu-nitrito-1kappa2O,O':2kappaO coordinating mode in copper(II) nitrite complexes with monoanionic tridentate Schiff base ligands: structure, magnetic, and electrochemical properties.  

PubMed

Three new copper(II) complexes, [CuL(1)(NO(2))](n) (1), [CuL(2)(NO(2))] (2), and [CuL(3)(NO(2))] (3), with three similar tridentate Schiff base ligands [HL(1) = 6-amino-3-methyl-1-phenyl-4-azahept-2-en-1-one, HL(2) = 6-amino-3-methyl-1-phenyl-4-azahex-2-en-1-one, and HL(3) = 6-diethylamino-3-methyl-1-phenyl-4-azahex-2-en-1-one] have been synthesized and characterized structurally and magnetically. In all three complexes, the tridentate Schiff base ligand and one oxygen atom of the nitrite ion constitute the equatorial plane around Cu(II), whereas the second oxygen atom of the nitrite ligand coordinates to one of the axial positions. In 1, this axially coordinated oxygen atom of the nitrite ligand also coordinates weakly to the other axial position of a Cu(II) ion of another unit to form a one-dimensional chain with the mu-nitrito-1kappa(2)O,O':2kappaO bridging mode. Complexes 2 and 3 are discrete monomers that are joined together by intermolecular H bonds and C-H....pi interactions in 2 and by only C-H....pi interactions in 3. A weak antiferromagnetism (J = -1.96(2) cm(-1)) is observed in complex 1 due to its asymmetric nitrite bridging. Complexes 2 and 3 show very weak antiferromagnetic interactions (J = -0.089 and -0.096 cm(-1), respectively) attributed to the presence of intermolecular H-bonding and C-H....pi interactions. The corresponding Cu(I) species produced by the electrochemical reduction of complexes 1 and 2 disproportionate to Cu(0) and Cu(2+,) whereas the reduced Cu(I) species of complex 3 seems to be stable presumably due to a higher tetrahedral distortion of the equatorial plane in 3 compared to that in 1 and 2. PMID:18998624

Sarkar, Biswarup; Konar, Sanjit; Gómez-García, Carlos J; Ghosh, Ashutosh

2008-12-15

24

Dinuclear cadmium(II), zinc(II), and manganese(II), trinuclear nickel(II), and pentanuclear copper(II) complexes with novel macrocyclic and acyclic Schiff-base ligands having enantiopure or racemic camphoric diamine components.  

PubMed

Four novel [3 + 3] Schiff-base macrocyclic ligands I-IV condensed from 2,6-diformyl-4-substituted phenols (R = CH(3) or Cl) and enantiopure or racemic camphoric diamines have been synthesized and characterized. Metal-ion complexations of these enantiopure and racemic [3 + 3] macrocyclic ligands with different cadmium(II), zinc(II), manganese(II), nickel(II), and copper(II) salts lead to the cleavage of Schiff-base C horizontal lineN double bonds and subsequent ring contraction of the macrocyclic ligands due to the size effects and the spatial restrictions of the coordination geometry of the central metals, the steric hindrance of ligands, and the counterions used. As a result, five [2 + 2] and one [1 + 2] dinuclear cadmium(II) complexes (1-6), two [2 + 2] dinuclear zinc(II) (7 and 8), and two [2 + 2] dinuclear manganese(II) (9 and 10) complexes together with one [1 + 1] trinuclear nickel(II) complex (11) and one [1 + 2] pentanuclear copper(II) complex (12), bearing enantiopure or racemic ligands, different substituent groups in the phenyl rings, and different anionic ligands (Cl(-), Br(-), OAc(-), and SCN(-)), have been obtained in which the chiral carbon atoms in the camphoric backbones are arranged in different ways (RRSS for the enantiopure ligands in 1, 2, 4, 5, and 7-10 and RSRS for the racemic ligands in 3, 6, 11, and 12). The steric hindrance effects of the methyl group bonded to one of the chiral carbon atoms of camphoric diamine units are believed to play important roles in the formation of the acyclic [1 + 1] trinuclear complex 11 and [1 + 2] dinuclear and pentanuclear complexes 6 and 12. In dinuclear cadmium(II), zinc(II), and manganese(II) complexes 1-10, the sequence of separations between the metal centers is consistent with that of the ionic radii shortened from cadmium(II) to manganese(II) to zinc(II) ions. Furthermore, UV-vis, circular dichroism, (1)H NMR, and fluorescence spectra have been used to characterize and compare the structural differences between related compounds. PMID:20515021

Jiang, Jue-Chao; Chu, Zhao-Lian; Huang, Wei; Wang, Gang; You, Xiao-Zeng

2010-07-01

25

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

26

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

27

Dielectric properties and conductivity studies of some tetradentate cobalt(II), nickel(II), and copper(II) Schiff base complexes  

Microsoft Academic Search

Dielectric and conductivity properties of cobalt(II), nickel(II), and copper(II)–imidazole-2-carboxaldehyde-glycylglycine (imal-glygly) complexes have been studied using impedance spectroscopy. The dielectric constant and dielectric loss factor for metal complexes have been analyzed in the frequency range from 1Hz to 1MHz at room temperature. The a.c. conductivity result reveals that these complexes exhibit dissimilar frequency dependent conductivity. An attempt has been made to

R. Selwin Joseyphus; E. Viswanathan; C. Justin Dhanaraj; J. Joseph

28

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

29

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

30

Synthesis and Spectral Characterization of 14- and 16-membered tetraazamacrocyclic Schiff base ligands and their transition metal complexes and a comparative study of interaction of calf thymus DNA with copper(II) complexes  

NASA Astrophysics Data System (ADS)

14 and 16 membered Schiff base macrocyclic ligands, 7,14-dimethyl-5,12-di(N-amino)-2-methylphenyl-1,4,8,11-tetraaza-cyclotetradecane-4,7,11,14-tetraene (L 1) and 8,16-dimethyl-6,14-di(N-amino)-2-methylphenyl-1,5,9,13-tetraaza-cyclohexadecane-5,8,13,16-tetraene (L 2) were synthesized by condensation reaction between 2'-methyleacetoacetanilide and aliphatic diamines. The metal complexes of the types, [ML 1](NO 3) 2 and [ML 2(NO 3) 2] [M = Co(II), Ni(II), Cu(II) and Zn(II)] were prepared by interaction of ligands, L 1 or L 2 with hydrated metal(II) nitrates. The ligands and their complexes were characterized by elemental analysis, IR, 1H and 13C NMR, EPR, UV-Vis spectroscopy, magnetic susceptibility, conductivity measurements and ESI-mass spectral studies. The results of elemental analyses, ESI-mass and conductivity measurements confirmed the stoichiometry of ligands and their complexes while the characteristic absorption bands and resonance peaks in IR and NMR spectra confirmed the formation of ligand frameworks around the metal ions. The square planar geometry for complexes derived from ligand L 1 and octahedral environment for complexes derived from ligand L 2 with distortion in Cu(II) complex have been confirmed on the basis of results of electronic and electron spin resonance spectral studies and magnetic moment measurements. Absorption and fluorescence spectral studies revealed different binding mode for complex, [CuL 1](NO 3) 2 as compared with [CuL 2(NO 3) 2] on interaction with calf thymus DNA.

Khan, Tahir Ali; Naseem, Sultana; Khan, Shahper N.; Khan, Asad U.; Shakir, Mohammad

2009-08-01

31

Synthesis and spectral characterization of 14- and 16-membered tetraazamacrocyclic Schiff base ligands and their transition metal complexes and a comparative study of interaction of calf thymus DNA with copper(II) complexes.  

PubMed

14 and 16 membered Schiff base macrocyclic ligands, 7,14-dimethyl-5,12-di(N-amino)-2-methylphenyl-1,4,8,11-tetraaza-cyclotetradecane-4,7,11,14-tetraene (L(1)) and 8,16-dimethyl-6,14-di(N-amino)-2-methylphenyl-1,5,9,13-tetraaza-cyclohexadecane-5,8,13,16-tetraene (L(2)) were synthesized by condensation reaction between 2'-methyleacetoacetanilide and aliphatic diamines. The metal complexes of the types, [ML(1)](NO(3))(2) and [ML(2)(NO(3))(2)] [M = Co(II), Ni(II), Cu(II) and Zn(II)] were prepared by interaction of ligands, L(1) or L(2) with hydrated metal(II) nitrates. The ligands and their complexes were characterized by elemental analysis, IR, (1)H and (13)C NMR, EPR, UV-Vis spectroscopy, magnetic susceptibility, conductivity measurements and ESI-mass spectral studies. The results of elemental analyses, ESI-mass and conductivity measurements confirmed the stoichiometry of ligands and their complexes while the characteristic absorption bands and resonance peaks in IR and NMR spectra confirmed the formation of ligand frameworks around the metal ions. The square planar geometry for complexes derived from ligand L(1) and octahedral environment for complexes derived from ligand L(2) with distortion in Cu(II) complex have been confirmed on the basis of results of electronic and electron spin resonance spectral studies and magnetic moment measurements. Absorption and fluorescence spectral studies revealed different binding mode for complex, [CuL(1)](NO(3))(2) as compared with [CuL(2)(NO(3))(2)] on interaction with calf thymus DNA. PMID:19403328

Khan, Tahir Ali; Naseem, Sultana; Khan, Shahper N; Khan, Asad U; Shakir, Mohammad

2009-03-31

32

Cobalt(II), Nickel(II) and Copper(II) complexes of a tetradentate Schiff base as photosensitizers: Quantum yield of 1O2 generation and its promising role in anti-tumor activity  

NASA Astrophysics Data System (ADS)

In the present investigation, a Schiff base N'1,N'3-bis[(E)-(5-bromo-2-hydroxyphenyl)methylidene]benzene-1,3-dicarbohydrazide and its metal complexes have been synthesized and characterized. The DNA-binding studies were performed using absorption spectroscopy, emission spectra, viscosity measurements and thermal denatuaration studies. The experimental evidence indicated that, the Co(II), Ni(II) and Cu(II) complexes interact with calf thymus DNA through intercalation with an intrinsic binding constant Kb of 2.6 × 104 M-1, 5.7 × 104 M-1 and 4.5 × 104 M-1, respectively and they exhibited potent photodamage abilities on pUC19 DNA, through singlet oxygen generation with quantum yields of 0.32, 0.27 and 0.30 respectively. The cytotoxic activity of the complexes resulted that they act as a potent photosensitizers for photochemical reactions.

Pradeepa, S. M.; Bhojya Naik, H. S.; Vinay Kumar, B.; Indira Priyadarsini, K.; Barik, Atanu; Ravikumar Naik, T. R.

2013-01-01

33

Designing dicyanamide bridged 1D molecular architecture from a mononuclear copper(II) Schiff base precursor: Syntheses, structural variations and magnetic study  

Microsoft Academic Search

A new tridentate N2O donor Schiff base ligand [(C6H5C(OH)CHC(CH3)NCH2C5H4N)LH] was obtained by 1:1 condensation of benzoylacetone with 2-picolylamine and has been used to synthesise a mononuclear [CuLCl] (1) and an end-to-end dicyanamide bridged polynuclear {[Cu2(?-L)2(?2-1,5-(CN)2N)]ClO4}n (2) copper(II) complexes. The ligand, 1 and 2 were clearly characterised by elemental analysis, FT-IR, 1H NMR, UV–Vis spectral studies, electrochemical studies and in addition

Aurkie Ray; Guillaume Pilet; Carlos J. Gómez-García; Samiran Mitra

2009-01-01

34

Synthesis, spectroscopy, electrochemistry and thermogravimetry of copper(II) tridentate Schiff base complexes, theoretical study of the structures of compounds and kinetic study of the tautomerism reactions by ab initio calculations  

NASA Astrophysics Data System (ADS)

Attempts to spectroscopic and structural study of copper complexes, some Cu(II) Schiff base complexes were synthesized and characterized by means of electronic, IR, 1HNMR spectra and elemental analysis. The thermal analyses of the complexes were investigated and the first order kinetic parameters were derived for them. The cyclic voltammetric studies in acetonitrile were proposed a monomeric structure for complexes. The structures of compounds were determined by ab initio calculations. In the solid state, the ligands exist as keto-amine/enol-imine tautomeric forms with an intramolecular hydrogen bond (Nsbnd H⋯O) between amine and carbonyl group. The kinetic studies of the tautomerism and equilibrium constant of the reactions were calculated using transition state theory. The optimized molecular geometry and atomic charges were calculated using MP2 method with 6-31G(d) basis set for H, C, N and O atoms and LANL2DZ for the Cu atom. The results suggested that, in the complexes, Cu(II) ion is in pseudo square-planar NO3 coordination geometry. Also the bond lengths and angles were studied and compared.

Kianfar, Ali Hossein; Ramazani, Shapour; Fath, Roghaye Hashemi; Roushani, Mahmoud

2013-03-01

35

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

36

Synthesis, spectral, structural, second-order nonlinear optical properties and theoretical studies on new organometallic donor-acceptor substituted nickel(II) and copper(II) unsymmetrical Schiff-base complexes.  

PubMed

The synthesis, spectroscopic and structural characterization, linear and nonlinear optical properties, as well as the electrochemical behavior of a series of robust neutral binuclear M[Fc-C(O)CH=C(CH(3))N-X-N=CH-(2-O,5-R-C(6)H(3))] (M = Ni (4), Cu (5), X = o-C(6)H(4), R = H; M = Ni (9), X = CH(2)CH(2), R = OH), and their corresponding ionic trinuclear [M{Fc-C(O)CH=C(CH(3))N-X-N=CH-(eta(6)-2-O,5-R-C(6)H(3))RuCp*}][PF(6)] (6, 7, 10), M[ONNO]-type unsymmetrical Salophen and salen complexes featuring ferrocenyl (Fc) donor and the mixed sandwich acceptor [Cp*Ru(eta(6)- salicylidene)](+) as a push-pull moiety are reported in this paper (Fc = CpFe(eta(5)-C(5)H(4)); Cp = eta(5)-C(5)H(5); Cp* = eta(5)-C(5)Me(5)). The single-crystal X-ray structure of the bimetallic iron-nickel derivative 4 indicates a bowed structure of the unsymmetrical Schiff base skeleton. The Ni(II) ion is tetracoordinated in a square planar environment, with two nitrogen atoms and two oxygen atoms as donors. The new metalloligand [Fc-C(O)CH=C(CH(3))N(H)CH(2)CH(2)N=CH-(2,5-(OH)(2)C(6)H(3))] (8) obtained from the Schiff base condensation of 2,5-dihydroxobenzaldehyde with the half-unit precursor, Fc-C(O)CH=C(CH(3))N(H)CH(2)CH(2)NH(2) (2), is reported with its crystal structure showing partial delocalization of the heteroconjugated [O-C-C-C-N] frameworks with a dihedral angle between the respective planes of 60.76 degrees. Second order nonlinear optical (NLO) measurements were achieved using the Harmonic Light Scattering technique to probe the role of the M[ONNO] chromophores and of the pi-complexation of the salicylidene ring in the nonlinearity. All the complexes exhibit a second-order nonlinear response increasing with the nuclearity, the hyperpolarizability (beta) value of the trinuclear complex 10 being 1.5 time larger than that of the metalloligand 8 (beta = 155 x 10(-30) esu). A rationalization of the structural, electronic, and redox properties of the title compounds is provided, based on a theoretical investigation at the density functional theory (DFT) level. Their UV-visible spectra has been assigned with the help of time-dependent (TD) DFT calculations. They are dominated by LMCT, MLCT, and pi-pi* transitions. PMID:20146541

Trujillo, Alexander; Fuentealba, Mauricio; Carrillo, David; Manzur, Carolina; Ledoux-Rak, Isabelle; Hamon, Jean-René; Saillard, Jean-Yves

2010-03-15

37

Designed synthesis of copper(II) and nickel(II) complexes with a tridentate N2O donor Schiff base: Modulation of crystalline architectures through CH⋯? and anion⋯? interactions  

NASA Astrophysics Data System (ADS)

Two copper(II) complexes, Cu(L1)Cl (1), Cu(L1)NCS (3) and two nickel(II) complexes Ni(L1)Cl (2), Ni(L1)NCS (4), where HL1 = 1-[(2-diethylamino-ethylimino)-methyl]-naphthalen-2-ol act as tridentate N2O donor ligand, have been prepared and characterized by elemental analysis, IR and UV-Vis spectroscopy and single crystal X-ray diffraction studies. The geometry of the central metal ion in each of the four complexes is square planar. The existence of CH⋯? interactions in 2 gives rise to one dimensional chain structure. Complex 3 shows two CH⋯? interactions and one anion⋯? interactions which leads to a two dimensional layer structure. Each mononuclear unit of 4 has two CH⋯? interactions along b axis to form a double strand one dimensional array of the molecules in crystal packing.

Das, Mithun; Chattopadhyay, Shouvik

2013-11-01

38

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

39

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

40

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

41

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

42

Synthesis and structural characterization of a carboxylate bridged tetranuclear copper complex derived from reduced Schiff base asymmetric compartmental ligand containing an amino acid side arm  

Microsoft Academic Search

The dinucleating asymmetric reduced Schiff base compartmental ligand H2L {2-[5-bromo-2-hydroxy-3-(4-methyl-piperazin-1-ylmethyl)-benzylamino]-propionic acid} (see Scheme 1 for H2L) gives the tetracopper(II) complex [Cu4L2(CH3COO)4]·2CH3CN·2H2O (1) on reaction with (CH3COO)2Cu·H2O. The single crystal X-ray structure of 1 reveals that this complex is a carboxylate bridged dimer of dinuclear copper(II) subunits, in which the copper(II) centers adopt different geometries, resulting in a {Cu4} complex.

Chullikkattil P. Pradeep; Panthapally S. Zacharias; Samar K. Das

2006-01-01

43

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

44

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

45

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

46

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

47

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

48

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

49

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

50

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

51

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

52

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

53

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

54

Synthesis, characterization, and X-ray crystal structures of metal complexes with new Schiff-base ligands and their antibacterial activities  

Microsoft Academic Search

Two new potentially hexadentate Schiff bases, [H2L] and [H2L], were prepared by condensation of 2-(3-(2-aminophenoxy)naphthalen-2-yloxy)benzenamine with 3,5-di-tert-butyl-2-hydroxy benzaldehyde and o-vanillin, respectively. Reaction of these ligands with cobalt(II) chloride, copper(II) perchlorate, and zinc(II) nitrate gave complexes ML. The ligands and their complexes have been characterized by a variety of physico-chemical techniques. The solid and solution state investigations show that the complexes

Hassan Keypour; Maryam Shayesteh; Reza Golbedaghi; Abdolkarim Chehregani; Allan G. Blackman

2012-01-01

55

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

56

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

57

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

58

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

59

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

60

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

61

Incorporation of a sodium ion guest in the host of copper(II)-Schiff-base complexes: Structural characterization and magnetic study  

Microsoft Academic Search

Three copper(II) complexes, [CuL1], [CuL2] and [CuL3] where L1, L2 and L3 are the tetradentate di-Schiff-base ligands prepared by the condensation of acetylacetone and appropriate diamines (e.g. 1,2-diaminoethane, 1,2-diaminopropane and 1,3-diaminopropane, respectively) in 2:1 ratios, have been prepared. These complexes act as host molecules and include a guest sodium ion by coordinating through the oxygen atoms to result in corresponding

Pampa Mukherjee; Michael G. B. Drew; Albert Figuerola; Ashutosh Ghosh

2008-01-01

62

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

63

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

64

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

65

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

66

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

67

Antibacterial Co(II), Ni(II), Cu(II) and Zn(II) complexes of Schiff bases derived from fluorobenzaldehyde and triazoles.  

PubMed

Antibacterial Schiff bases derived from 1,2,4-triazoles as well as their metal complexes incorporating cobalt(II), nickel(II), copper(II) and zinc(II) have been synthesized and characterized. Physico-chemical studies suggest that an octahedral geometry for the cobalt(II), nickel(II) and zinc(II)and square-planer geometry for the copper(II) complexes. These complexes have been screened for antibacterial activity against three Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis) and two Gram-negative (Salmonella typhi and Pseudomonas aeruginosa) bacterial strains, and results compared with the activity of the free ligands. The metal complexes were found to be more potent against one or more bacterial strains than the free ligands. PMID:17194027

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

2006-10-01

68

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

69

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

70

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

71

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

72

Synthesis, characterization, and biological properties of Ni(II), Co(II), and Cu(II) complexes of Schiff bases derived from 4-aminobenzylamine  

Microsoft Academic Search

New Schiff bases, N,N?-bis(salicylidene)-4-aminobenzylamine (H2L), N,N?-bis(3-methoxysalicylidene)-4-aminobenzylamine (H2L), and N,N?-bis(4-hydroxysalicylidene)-4-aminobenzylamine (H2L), with their nickel(II), cobalt(II), and copper(II) complexes have been synthesized and characterized by elemental analyses, electronic absorption, FT-IR, magnetic susceptibility, and conductance measurements. For the ligands, H and C NMR and mass spectra were obtained. The tetradentate ligands coordinate to the metal ions through the phenolic oxygen and azomethine nitrogens.

Cah?t Demetgül; Mürüvvet Karakaplan; Selahatt?n Ser?n; Met?n Di?rak

2009-01-01

73

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

74

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

75

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

76

Syntheses of Copper(II) Coordination Compounds of New Schiff Bases Derived from 4Amino5Mercapto3Methyl1,2,4Triazole and ?-Diketones, Hydroxyacetone, and Hydroxybenzophenone  

Microsoft Academic Search

Eight new copper(II) coordination compounds of the Schiff bases derived from 4-amino-5-mercapto-3-methyl-1,2,4-triazole and acetylacetone, acetoacetanilide, acetoacet-Q-toluidide, acetoacet-Q-anisidide, benzoylacetanilide, Q-hydroxyacetophenons, Q-hydroxybenzophenone, and hydroxyacetone have been synthesized and characterized on the basis of elemental analyses, magnetic susceptibility, infrared and electronic spectral measurements. The Schiff bases behave as SNO donor, tridentate, dibasic ligands and form copper(II) coordination compounds with 1:1 metal: ligand stoichiometry,

A. Syamal; M. A. Bari Niazi

1985-01-01

77

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

78

Spectrometric study of tautomeric and protonation equilibria of o-vanillin Schiff base derivatives and their complexes with Cu(II)  

NASA Astrophysics Data System (ADS)

Electronic absorption and emission properties of a series of Schiff bases derived from 2-hydroxy-3-methoxybenzaldehyde and 2-aminopyridine, 2,3-diaminopyridine, 2,6-diaminopyridine, or 3-aminomethylpyridine were studied in solvents of different polarities. The interconversion of the enolimine to the ketoamine tautomeric form was observed for compound 1, 6-methoxy-2-(3-pyridylmethyliminomethyl)phenol, and the corresponding equilibrium constant was estimated in several solvents. Protonation constants of all the investigated compounds were determined spectrophotometrically in the methanol/water 1/4 system. The effect of copper(II) ions on absorption and on the emission spectra of these ligands was examined in the buffered dioxane/water 1/1 system (pH 5.8). Strong complexation of Cu(II) and formation of a 1:1 complex were observed for the bis-Schiff base derived from 2,3-diaminopyridine. The complex of copper(II) with compound 1 was isolated and characterized by elemental analysis, magnetic susceptibility measurement, UV-vis and IR spectrometry.

Gali?, Nives; Cimerman, Zvjezdana; Tomiši?, Vladislav

2008-12-01

79

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: MeOcomplexes were carried out in the range of 20-700°C. The VOL(1)(OH(2)) decomposed in two steps whereas the remaining six complexes decomposed in three steps. The thermal decomposition of these complexes is closely related to the nature of the Schiff base ligands and proceeds via first order kinetics. PMID:21803644

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

2011-07-12

80

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

81

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

82

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

83

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

84

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

85

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

86

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

87

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

88

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

89

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

90

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

91

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

92

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

93

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

94

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

95

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

96

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

97

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

98

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

99

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

100

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

101

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

102

Nonplanar manganese Schiff-base complexes; synthesis and molecular structures  

Microsoft Academic Search

The reactions of anhydrous sodium salts of three chiral biaryl-bridged salicylaldimine tetradentate proligands H2L with manganese(II) chloride give the corresponding solvated complexes [MnIIL]. The molecular structure of one chiral nonracemic example with a relatively low steric demand ligand set is shown to be composed of a homochiral dimer with bridging phenoxy groups. Both LMn units adopt the cis-? structure with

Christopher J. Sanders; Paul N. O'Shaughnessy; Peter Scott

2003-01-01

103

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

104

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

105

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

106

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

107

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

108

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

109

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

110

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

111

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

112

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

113

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

114

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

115

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

116

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

117

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

118

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

119

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

120

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

121

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

122

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

123

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

124

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

125

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

126

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

127

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

128

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

129

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

130

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

131

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

132

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

133

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

134

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

135

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

136

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

137

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

138

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

139

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

140

Synthesis and characterization of taurine Schiff base derivatives and their Cu(II) complexes: crystal and molecular structure of 5-NO/sub 2/ salicylaldimine ethylene sulfonic acid complex of Cu(II)  

SciTech Connect

Spectroscopic analysis of eight copper(II) complexes of Schiff bases derived from taurine and eight different salicylaldehydes and naphthaldehydes are reported. X-ray structural analysis of the copper(II) complex of the 5-NO/sub 2/-salicylaldehyde imine of taurine (5-NO/sub 2/-salicylaldimine ethylene sulfonic acid) as the tetra n-butylammonium salt (Cu(C/sub 9/H/sub 8/N/sub 2/O/sub 6/S)/sub 2/)/sup 2 -/2((C/sub 4/H/sub 9/)/sub 4/N)/sup +/ (CUTAUTBA) has been carried out. The space group is P anti 1, with a = 8.761(4), b = 10.410(3), c = 16.528(4) A, ..cap alpha.. = 77.85(3), ..beta.. = 86.53(4), ..gamma.. = 79.15(3)/sup 0/, and Z = 1. The structure was solved by the heavy-atom method and refined by least-squares techniques to an R factor of 0.068 for 2807 observed reflections. The CUTAU cation is centrosymmetric, with the Cu atom sitting on a crystallographic center of symmetry. The copper atom has a square-planar environment, coordinated by the potentially tridentate Schiff base only through the imino nitrogen and the phenolate oxygen with the deprotonated sulfonic group directed away from the coordination sphere of the Cu(II).

Perez-Cesar, M.C.; Soriano-Garcia, M.; Toscano, R.A.; Gomez-Lara, J.

1986-04-01

141

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

142

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

143

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

144

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

145

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

146

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

147

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

148

A novel 1D chain of azido bridged copper(II) with a salen-type di-Schiff base ligand  

NASA Astrophysics Data System (ADS)

One new complex of Cu(II), [(CuL)2Cu3(N3)6]n (1) has been synthesized by reacting the "ligand complex", [CuL] with copper acetate and sodium azide (NaN3) in methanol-water where the di-Schiff base ligand H2L = N,N?-bis(?-methylsalicylidene)-1,3-propanediamine. The X-ray single crystal structural analysis shows that complex 1 consists of an incomplete face-sharing double cube of four Cu(II) ions with the formula of [(CuL)2Cu2(N3)2]2+ which are connected by [Cu(N3)4]2- unit to form a novel 1D chain.

Biswas, Saptarshi; Ghosh, Ashutosh

2012-07-01

149

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

150

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

151

Spacer-dependent structural and physicochemical diversity in copper(II) complexes with salicyloyl hydrazones: a monomer and soluble polymers.  

PubMed

Complexation of copper(II) with a series of heterodonor chelating Schiff bases (LL) of salicylic acid hydrazide and aliphatic or cycloaliphatic ketones affords soluble one-dimensional (1D) metallopolymers containing Schiff bases as bridging ligands. Single-crystal X-ray diffraction results reveal nanometer-sized metallopolymeric wires [Cu(?-LL)(2)](n) with off-axis linkers and a zigzag geometry. Octahedrally coordinated copper centers, exhibiting a Jahn-Teller distortion, are doubly bridged by two Schiff-base molecules in the ?(2)-?(1),?(2) coordination mode. The use of dibutylketone with long alkyl chains as a component for Schiff base formation leads to a distorted square planar monomeric copper(II) complex [Cu(LL)(2)], as evidenced by its X-ray crystal structure. The compounds are characterized by elemental analyses and IR and UV-vis spectroscopy, as well as magnetic susceptibility and cyclic voltammetry measurements. Electrochemical studies on the complexes reveal an existence of polymeric and monomeric forms in solution and the dependence of Cu(II)/Cu(I) reduction potentials on alkyl groups of salicyloyl hydrazone ligands. Polymeric complexes form conducting films on Pt electrodes upon multicycle potential sweeps. PMID:21428390

Matoga, Dariusz; Szklarzewicz, Janusz; Grybo?, Ryszard; Kurpiewska, Katarzyna; Nitek, Wojciech

2011-03-23

152

Synthesis, spectroscopic characterization and DNA nuclease activity of Cu(II) complexes derived from pyrazolone based NSO-donor Schiff base ligands  

NASA Astrophysics Data System (ADS)

Two neutral mononuclear Cu(II) complexes have been prepared in EtOH using Schiff bases derived from 4-toluoyl pyrazolone and thiosemicarbazide. Both the ligands have been characterized on the basis of elemental analysis, IR, 1H NMR, 13C NMR and mass spectral data. The molecular geometry of one of these ligands has been determined by single crystal X-ray study. It reveals that these ligands exist in amine-one tautomeric form in the solid state. Microanalytical data, Cu-estimation, molar conductivity, magnetic measurements, IR, UV-Visible, FAB-Mass, TG-DTA data and ESR spectral studies were used to confirm the structures of the complexes. Electronic absorption and IR spectra of the complexes suggest a square-planar geometry around the central metal ion. The interaction of complexes with pET30a plasmid DNA was investigated by spectroscopic measurements. Results suggest that the copper complexes bind to DNA via an intercalative mode and can quench the fluorescence intensity of EB bound to DNA. The interaction between the complexes and DNA has also been investigated by agarose gel electrophoresis, interestingly, we found that the copper(II) complexes can cleave circular plasmid DNA to nicked and linear forms.

Vyas, Komal M.; Joshi, Rushikesh G.; Jadeja, R. N.; Ratna Prabha, C.; Gupta, Vivek K.

2011-12-01

153

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

154

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

155

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

156

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

157

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

158

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

159

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

160

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

161

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

162

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

163

Metal-free and dicopper(II) complexes of Schiff base [2 + 2] macrocycles derived from 2,2'-iminobisbenzaldehyde: syntheses, structures, and electrochemistry.  

PubMed

Three new bis-terdentate Schiff base [2 + 2] macrocycles (H(2)L(Et), H(2)L(Pr), and H(2)L(Bu)) have been prepared in high yields by 1:1 condensation of 2,2'-iminobisbenzaldehyde with 1,2-diaminoethane, 1,3-diaminopropane, and 1,4-diaminobutane, respectively. Metalation of these macrocycles yields the corresponding dicopper(II) acetate (1, 2, and 3) and tetrafluoroborate (4, 5, and 6) complexes. The structures of H(2)L(Et), H(2)L(Pr), H(2)L(Bu), [Cu(II)(2)L(i)(OAc)(2)]·solvents (where i is Et, Pr or Bu) and [Cu(II)(2)L(Pr)(DMF)(4)] (BF(4))(2)·0.5H(2)O are reported. Intramolecular hydrogen bonding is a feature of the metal-free macrocycles. The copper(II) centers in [Cu(II)(2)L(i)(OAc)(2)]·solvents are four coordinate, and the macrocycles have U-shaped (Et, Bu) or stepped (Pr) conformations. Complex 5 crystallizes with two dimethylformamide (DMF) molecules bound per five coordinate copper(II) center. Electrochemical studies revealed ligand based oxidations for all of the macrocycles and complexes. Complexes 1 and 2 undergo two quasi-reversible oxidations in DCM which are associated with the deposition of a visible film on the electrode after multiple scans in this oxidative region, suggestive of electropolymerization. Complexes 4-6, studied in MeCN, have Cu(II) ? Cu(I) redox potentials at more positive potentials than for 1-3. PMID:21417228

Cameron, Scott A; Brooker, Sally

2011-03-21

164

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

165

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

166

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

167

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

168

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

169

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

170

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 Mecomplexes were carried out in the range of 20-700°C. The complexes were decomposed in two stages. Also, decomposition of the synthesized complexes is related to the Schiff 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

171

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

172

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

173

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

174

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

175

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

176

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

177

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

178

Synthesis, characterization and structures of copper(II) complexes containing carboxylate and sulfonate groups  

Microsoft Academic Search

Four copper(II) complexes containing Schiff base and reduced Schiff base ligands derived from pyridine-2-aldehyde and amino\\u000a acid containing carboxylate and sulfonate functional groups (N-(2-pyridylmethylene)-amino acid and N-(2-pyridylmethyl)-amino acid, (amino acids = ?-alanine and aminoethanesulfonic acid) namely, [Cu(Pbals)(H2O)2]ClO4·H2O 1, [Cu(Pbal)(ClO4)(H2O)] 2, [Cu2(Paes)2(ClO4)2]·2H2O 3, and [Cu(Pae)(H2O)]·ClO4·H2O 4 have been synthesized and characterized. The structural features of carboxylate and sulfonate donor groups have been elucidated.

Wei Lee Leong; Jagadese J. Vittal

179

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

180

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

181

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

182

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

183

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

184

Synthesis and characterization of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of chromone based azo-linked Schiff base ligand  

NASA Astrophysics Data System (ADS)

Azo-Schiff-base complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized and characterized by elemental analysis, IR, UV-Vis, 1H NMR, mass spectra, molar conductance, magnetic susceptibility measurement, electron spin resonance (EPR), CV, fluorescence, NLO and SEM. The conductance data indicate the nonelectrolytic nature of the complexes, except VO(II) complex which is electrolytic in nature. On the basis of electronic spectra and magnetic susceptibility octahedral geometry has been proposed for the complexes. The EPR spectra of copper and oxovanadium complexes in DMSO at 300 and 77 K were recorded and its salient features are reported. The redox behavior of the copper(II) complex was studied using cyclic voltammetry. The in vitro antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella enterica typhi, Bacillus subtilis and Candida strains was studied and compared with that of free ligand by well-diffusion technique. The azo Schiff base exhibited fluorescence properties originating from intraligand (?-??) transitions and metal-mediated enhancement is observed on complexation and so the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. On the basis of the optimized structures, the second-order nonlinear optical properties (NLO) are calculated by using second-harmonic generation (SHG) and also the surface morphology of the complexes was studied by SEM.

Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Johnson Raja, S.

2012-12-01

185

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

186

A rare ferromagnetically coupled asymmetric doubly azido bridged copper(II) dimer with an N, N, O donor Schiff base  

Microsoft Academic Search

A new end-to-end (EE) doubly azido bridged dinuclear complex [Cu2L2(?1,3-N3)2] (1) [where L=(E)-4-(2-(dimethylamino)ethylimino)-1,1,1-trifluoropentan-2-one)] has been synthesized and characterized by elemental and spectroscopic techniques. Single crystal X-ray diffraction analysis reveals that the dimeric complex possesses a center of inversion. Each copper atom in 1 is in a distorted square pyramidal geometry with a CuN4O chromophore as revealed from the ? value,

Shyamapada Shit; Pritha Talukder; Joy Chakraborty; Guillaume Pilet; M. Salah El Fallah; Joan Ribas; Samiran Mitra

2007-01-01

187

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

188

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

189

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

190

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

191

Spectral, magnetic, biocidal screening, DNA binding and photocleavage studies of mononuclear Cu(II) and Zn(II) metal complexes of tricoordinate heterocyclic Schiff base ligands of pyrazolone and semicarbazide/thiosemicarbazide based derivatives.  

PubMed

We depict the synthesis and characterization of copper(II) and zinc(II) coordination compounds of 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-semicarbazone (1a), 4-(3',4'-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone (1b), 4-(3'-hydroxy-4'-nitrobenzaldehydene)2-3-dimeth yl-1-phenyl-3-pyrazolin-5-semicarbazone (1c) and 4-(3'-hydroxy-4'-nitrobenzal dehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone (1d). All the remote compounds have the general composition [ML(2)] (M=Cu(II) and Zn(II)); L=Schiff base (1a-1d). All the complexes were characterized by elemental analysis, molar conductivity, IR, (1)H NMR, UV-vis, ESI-Mass, magnetic susceptibility measurements, cyclic voltammetric measurements, and EPR spectral studies. It has been originated that the Schiff bases with Cu(II) and Zn(II) ions form mononuclear complexes on 1:2 (metal:ligand) stoichiometry. Distorted octahedral environment is suggested for the metal complexes. The conductivity data confirm the non-electrolytic nature of the complexes. The interaction of CuL(2)(1a-1d) complexes with CT DNA was investigated by spectroscopic, electrochemical and viscosity measurements. Results suggest that the copper complexes bind to DNA via an intercalative mode. Moreover, the complexes have been found to promote the photocleavage of plasmid DNA pBR322 under irradiation at 365 nm. The Schiff bases and their metal complexes were screened for their antifungal and antibacterial activities against different species of pathogenic fungi and bacteria and their biopotency has been discussed. PMID:20363662

Raman, N; Selvan, A; Manisankar, P

2010-03-19

192

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

193

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

194

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

195

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

196

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

197

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

198

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

199

Synthesis, spectral characterization, in vitro antibacterial, antifungal and cytotoxic activities of Co(II), Ni(II) and Cu(II) complexes with 1,2,4-triazole Schiff bases.  

PubMed

A series of metal complexes of cobalt(II), nickel(II) and copper(II) have been synthesized with newly synthesized biologically active 1,2,4-triazole Schiff bases derived from the condensation of 3-substituted-4-amino-5-mercapto-1,2,4-triazole and 8-formyl-7-hydroxy-4-methylcoumarin, which have been characterized by elemental analyses, spectroscopic measurements (IR, UV-vis, fluorescence, ESR), magnetic measurements and thermal studies. Electrochemical study of the complexes is also reported. All the complexes are soluble to limited extent in common organic solvents but soluble to larger extent in DMF and DMSO and are non-electrolytes in DMF and DMSO. All these Schiff bases and their complexes have also been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa and Salmonella typhi) and antifungal activities (Aspergillus niger, Aspergillus flavus and Cladosporium) by MIC method. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties. PMID:18395942

Bagihalli, Gangadhar B; Avaji, Prakash Gouda; Patil, Sangamesh A; Badami, Prema S

2008-02-29

200

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

201

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

202

Synthesis, spectral characterization, molecular modeling, thermal study and biological evaluation of transition metal complexes of a bidentate Schiff base ligand  

NASA Astrophysics Data System (ADS)

Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized [where L = 3-Bromoacetophenone thiosemicarbazone and X = CH3COO-, Cl- and NO3-]. All the complexes were characterized by elemental analysis, magnetic moments, IR, electronic and EPR spectral studies. The ligand behaved as bidentate and coordinated through sulfur of sbnd Cdbnd S group and nitrogen atoms of sbnd Cdbnd N group. The copper(II) and nickel(II) complexes were found to have magnetic moments 1.94-2.02 BM, 2.96-3.02 BM respectively which was corresponding to one and two unpaired electrons respectively. The molar conductance of the complexes in solution of DMSO lies in the range of 10-20 ?-1 cm2 mol-1 indicating their non-electrolytic behavior. On the basis of EPR, electronic and infrared spectral studies, tetragonal geometry has been assigned for copper(II) complexes and an octahedral geometry for nickel(II) complexes. The values of Nephelauxetic parameter ? lie in the range 0.19-0.37 which indicated the covalent character in metal ligand '?' bond. Synthesized ligand and its copper(II) and nickel(II) complexes have also been screened against different bacterial and fungal species which suggested that complexes are more active than the ligands in antimicrobial activities.

Chandra, Sulekh; Bargujar, Savita; Nirwal, Rita; Qanungo, Kushal; Sharma, Saroj K.

2013-09-01

203

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

204

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

205

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

206

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

207

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

208

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

209

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

210

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

211

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

212

Spectral, magnetic, biocidal screening, DNA binding and photocleavage studies of mononuclear Cu(II) and Zn(II) metal complexes of tricoordinate heterocyclic Schiff base ligands of pyrazolone and semicarbazide\\/thiosemicarbazide based derivatives  

Microsoft Academic Search

We depict the synthesis and characterization of copper(II) and zinc(II) coordination compounds of 4-(3?,4?-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-semicarbazone (1a), 4-(3?,4?-dimethoxybenzaldehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone (1b), 4-(3?-hydroxy-4?-nitrobenzaldehydene)2-3-dimeth yl-1-phenyl-3-pyrazolin-5-semicarbazone (1c) and 4-(3?-hydroxy-4?-nitrobenzal dehydene)2-3-dimethyl-1-phenyl-3-pyrazolin-5-thiosemicarbazone (1d). All the remote compounds have the general composition [ML2] (M=Cu(II) and Zn(II)); L=Schiff base (1a–1d). All the complexes were characterized by elemental analysis, molar conductivity, IR, 1H NMR, UV–vis, ESI-Mass, magnetic susceptibility measurements, cyclic voltammetric measurements,

N. Raman; A. Selvan; P. Manisankar

2010-01-01

213

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

214

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

215

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

216

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

217

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

218

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

219

Synthesis, crystal structure, spectral and magnetic studies and catecholase activity of copper(II) complexes with di- and tri-podal ligands  

Microsoft Academic Search

Five complexes of copper(II) acetate with Schiff base ligands based on salicylaldehyde and N,N-dimethylamino)ethyl\\/propyl amine and their reduced products, have been synthesized and characterized by various spectroscopic methods. The solid state structures of 1, 2 and 3 have been determined using single crystal X-ray diffraction method. The structures of the other two compounds have been proposed on the basis of

Vimal K. Bhardwaj; Núria Aliaga-Alcalde; Montserrat Corbella; Geeta Hundal

2010-01-01

220

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

221

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

222

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

223

Two ferromagnetic azido-bridged copper(II) complexes studied by first-principle electronic-structure calculation  

NASA Astrophysics Data System (ADS)

The electronic structures of two ferromagnetic polynuclear copper(II) complexes, derived from end-to-end azido ligand and tridentate (NNN donor) Schiff base ligand, have been studied using the full-potential linearized augmented plane-wave method based on the density-functional theory. They are [Cu(L1)(?-1,3-N3)]n(ClO4)n (1) and [Cu(L2)(?-1,3-N3)]n(ClO4)n (2). The result shows that the spin populations in these two complexes are mainly distributed on the equatorial planes of a square pyramidal that surround the copper(II) ions. There are large and positive spin populations on copper(II) ions, small and positive spin populations on the three nitrogen atoms of tridentate Schiff base ligand, and the two terminal nitrogen atoms of asymmetrical end-to-end azido ligand, while weak and negative spin populations on the central nitrogen atoms of asymmetrical end-to-end azido ligand. Ferromagnetic coupling through the asymmetrical azido ligand in these two complexes has been mainly attributed to the spin delocalization, also with weak spin-polarization effect.

Zhang, Y. S.; Yao, K. L.; Liu, Z. L.

2005-09-01

224

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

225

Synthesis, X-ray crystal structure and magnetic study of a ?1,5-dca bridged ferromagnetic dimeric copper(II) complex  

Microsoft Academic Search

Reaction of Cu(NO3)2 · 3H2O, 1-(N-salicyalideneimine)-2-(N,N-dimethyl)-aminoethane (HL), LiClO4, and sodium dicyanamide (Nadca) in aqueous medium affords a dimeric complex [Cu2(L)2 (?1,5-dca)](ClO4) (1). Single crystal X-ray analysis reveals that 1 is dinuclear with copper(II) ions bridged by a single dicyanamide group in end-to-end fashion. The coordination environment around copper(II) is square planar. Two nitrogens and oxygen of the tridentate Schiff-base ligand

Dasarath Mal; Rupam Sen; Chandan Adhikary; Yoshitaro Miyashita; Ken-Ichi Okamoto; Ashis Bhattacharjee; Philipp Gütlich; Subratanath Koner

2008-01-01

226

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

227

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

228

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

229

Synthesis, Properties and Crystal Structures of Mononuclear Copper(II) Complexes with Bis(2-Pyridylmethyl)Amino Acids  

Microsoft Academic Search

Tetradentate Schiff-base carboxylate-containing ligands, bis(2-pyridylmethyl)amino-3-propionic acid (Hpmpa) and bis(2-pyridylmethyl)amino-4-butyric acid (Hpmba), react with CuCl2 to give rise to the mononuclear complexes [Cu(Hpmpa)Cl]Cl · 2H2O (1) and [Cu(Hpmba)Cl2]· H2O (2). These complexes have been characterized by X-ray crystallography, spectroscopic and cyclic voltammetry. Crystal structure of (1) shows that the copper(II) ion has a distorted square-pyramidal geometry with the three nitrogen atoms

Ki-Young Choi; Yong-Man Jeon; Kyu-Chul Lee; Suk-Nam Choi; Moon-Won Kim; Hae-Hwan Lim; Moon-Jip Kim

2004-01-01

230

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

231

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

232

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

233

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

234

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

235

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

236

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

237

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

238

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

239

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

240

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

241

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

242

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

243

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.

244

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

245

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde.  

PubMed

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, (1)H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 ?m. PMID:22728967

Anitha, C; Sheela, C D; Tharmaraj, P; Sumathi, S

2012-06-02

246

Spectroscopic studies and biological evaluation of some transition metal complexes of azo Schiff-base ligand derived from (1-phenyl-2,3-dimethyl-4-aminopyrazol-5-one) and 5-((4-chlorophenyl)diazenyl)-2-hydroxybenzaldehyde  

NASA Astrophysics Data System (ADS)

A series of metal(II) complexes of VO(II), Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized from the azo Schiff base ligand 4-((E)-4-((E)-(4-chlorophenyl)diazenyl)-2-hydroxybenzylideneamino)-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one (CDHBAP) and characterized by elemental analysis, spectral (IR, UV-Vis, 1H NMR, ESR and EI-mass), magnetic moment measurements, molar conductance, DNA, SEM, X-ray crystallography and fluorescence studies. The electronic absorption spectra and magnetic susceptibility measurements of the complexes indicate square pyramidal geometry for VO(II) and octahedral geometry for all the other complexes. The important infrared (IR) spectral bands corresponding to the active groups in the ligand and the solid complexes under investigation were studied and implies that CDHBAP is coordinated to the metal ions in a neutral tridentate manner. The redox behavior of copper(II) and vanadyl(II) complexes have been studied by cyclic voltammetry. The nuclease activity of the above metal(II) complexes shows that the complexes cleave DNA. All the synthesized complexes can serve as potential photoactive materials as indicated from their characteristic fluorescence properties. The antibacterial and antifungal activities of the synthesized ligand and its metal complexes were screened against bacterial species (Staphylococcus aureus, Salmonella typhi, Escherichia coli, Bacillus subtilis, Shigella sonnie) and fungi (Candida albicans, Aspergillus niger, Rhizoctonia bataicola). Amikacin and Ketoconozole were used as references for antibacterial and antifungal studies. The activity data show that the metal complexes have a promising biological activity comparable with the parent Schiff base ligand against bacterial and fungal species. The second harmonic generation (SHG) efficiency of the ligand was measured and the NLO (non-linear optical) properties of the ligand are expected to result in the realization of advanced optical devices in optical fiber communication (OFC) and optical computing. The SEM image of the copper(II) complex implies that the size of the particles is 1 ?m.

Anitha, C.; Sheela, C. D.; Tharmaraj, P.; Sumathi, S.

2012-10-01

247

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

248

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

249

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

250

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

251

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

252

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

253

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

254

Synthesis and characterization of some Schiff base transition metal complexes derived from vanillin and L(+)alanine  

Microsoft Academic Search

The cobalt(II), nickel(II), copper(II) and zinc(II)-vanillidene-L(+)alanine complexes were synthesized and characterized by\\u000a elemental analysis, conductivity measurements, magnetic behavior, infrared, electronic spectral measurements, X-ray powder\\u000a diffraction and biological studies. The conductance measurements indicate that all the complexes are non-electrolytes. The\\u000a infrared spectra indicate the coordination of imino nitrogen, phenolic oxygen and carboxylato oxygen atoms. The electronic\\u000a spectral measurements demonstrate that cobalt(II)

R. Selwin Joseyphus; C. Justin Dhanaraj; M. Sivasankaran Nair

2006-01-01

255

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

256

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

257

A novel bioactive tyramine derived Schiff base and its transition metal complexes as selective DNA binding agents  

NASA Astrophysics Data System (ADS)

A novel tyramine derived Schiff base, 3-4-dimethoxybenzylidene-4-aminoantipyrinyl-4-aminoethylphenol(L) and a series of its transition metal complexes of the type, ML 2Cl 2 where, M = Cu(II), Ni(II), Co(II) and Zn(II) have been designed and synthesized. Their structural features and other properties were deduced from the elemental analysis, magnetic susceptibility and molar conductivity as well as from mass, IR, UV-vis, 1H NMR and EPR spectral studies. The binding properties of these complexes with calf thymus DNA (CT-DNA) were investigated using electronic absorption spectroscopy, viscosity measurement, cyclic voltammetry and molecular docking analysis. The results reveal that the metal(II) complexes interact with DNA through minor groove binding. The interaction has also been investigated by gel electrophoresis. Interestingly, it was found that all the complexes could cleave the circular plasmid pUC19 super coiled (SC) DNA efficiently in the presence of AH 2 (ascorbic acid). The complexes showed enhanced antifungal and antibacterial activities compared to the free ligand.

Raman, N.; Sobha, S.; Thamaraichelvan, A.

2011-02-01

258

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

259

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

260

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.

261

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

262

Synthesis, spectroscopic and thermal studies of some IIB group complexes with a new N2-Schiff base ligand.  

PubMed

Synthesis, spectroscopic and thermal studies of some complexes of a new N(2)-Schiff base ligand of N(1),N(2)-bis((E)-2-methyl-3-phenylallylidene)ethane-1,2-diamine (L) with a general formula of MLX(2) (M = Zn(II), Cd(II) and Hg(II); X = Cl(-), Br(-), I(-), SCN(-) and N(3)(-)) are described. The ligand and its complexes were characterized by elemental analysis, molar conductance, UV-vis spectra, FT-IR spectra, MS, (1)H NMR and (13)C NMR spectra. The conductivity measurement as well as spectral data indicated that the complexes are non-electrolyte. (1)H and (13)C NMR spectra have been studied in DMSO-d(6) and/or CDCl(3). The thermal behavior of the complexes shows weight loss by decomposition of the anions and ligand segments in the subsequent steps. Activation thermodynamic parameters of decomposition such as E*, ?H*, ?S* and ?G* were calculated from TG curves. PMID:21733744

Montazerozohori, Morteza; Khani, Sara; Tavakol, Hosein; Hojjati, Ahmad; Kazemi, Mostafa

2011-06-17

263

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

264

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

265

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

266

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

267

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

268

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

269

Synthesis, Characterization, and Electrochemical Study of Complexes with 4,4?Bis(Salicylideneimino) Diphenylether and Cobalt(II), Copper(II), Zinc(II), and Cadmium(II)  

Microsoft Academic Search

The 4,4?-bis(salicyleneimino) diphenyl ether is a N2O3 Schiff base but it acts as a tetradentate ligand. Its complexes with cobalt (II), copper(II), zinc(II), and cadmium (II) were characterised using spectroscopic determinations, d.s.c. and cyclic voltammetry. In these compounds, the coordination occurs through the non-ionised phenolic hydroxyl of the ligand and the nitrogen atom of the azomethine moiety. These new complexes

S. Issaadi; D. Haffar; T. Douadi; S. Chafaa; D. Séraphin; M. A. Khan; Gilles Bouet

2005-01-01

270

Synthesis and structural analysis of copper(II) cysteine complexes  

Microsoft Academic Search

This report describes the synthesis and structural analysis of stable copper(II) cysteine complexes. Pale pink copper(II) cysteine complexes were synthesized in mole ratios of 1:2, 1:4, and 1:6 of copper(II):cysteine in ethanol. Infrared spectroscopy and X-ray absorption spectroscopy confirmed that copper(II) binding occurred via the thiol ligand of cysteine. XANES analysis showed that the oxidation state of copper remained as

Kenneth M. Dokken; Jason G. Parsons; John McClure; Jorge L. Gardea-Torresdey

2009-01-01

271

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

272

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

273

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

274

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

275

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

276

Two new copper(II) complexes with the shortest (N N) diazine based rigid ligand: Example of unusual tridentate coordination mode  

NASA Astrophysics Data System (ADS)

Two new five coordinated Cu(II) complexes, Cu(L)Cl2,CH3OH (1) and Cu(L)Br2 (2) derived from the flexidentate ligand (L), 2-pyridinealdazine, have been synthesised and characterised by spectroscopic and electrochemical studies. Single crystal structures of the complexes were determined. Crystal structures of both the complexes contain monomeric entities of five coordinated copper(II) ions where the Schiff base ligand, 2-pyridinealdazine, acts in a tridentate fashion. The central part of the ligand in complex 2 is disordered over two positions: N8N9 make up the major position and N8AN9A make up the minor position.

Karmakar, Ruma; Choudhury, Chirantan Roy; Batten, Stuart R.; Mitra, Samiran

2007-01-01

277

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

278

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

279

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

280

Synthesis, electrochemical and photophysical properties of heterodinuclear Ru-Mn and Ru-Zn complexes bearing ambident Schiff base ligand.  

PubMed

While ruthenium tris(diimine) complexes have been extensively studied, this is not the case with ruthenium bis(diimine)X(2) complexes where X represents a pyridinyl-based ligand. The synthesis of a new complex ([2][PF(6)](2)) bearing two ambident Schiff base ligands (HL) constituted by the assembly of phenol and pyridinyl moieties is reported. Thanks to the heteroditopic property of HL, compound [2](2+) was used as an original metalloligand for the coordination of a redox-active (Mn(III)) and redox-inactive (Zn(II)) second metal cation affording three heterodinuclear complexes, namely, [(bpy)(2)Ru(2)Mn(acac)][PF(6)](2) ([3][PF(6)](2); acac = acetylacetonate), [(bpy)(2)Ru(2)Mn(OAc)][PF(6)](2) ([4][PF(6)](2), OAc = acetate), and [(bpy)(2)Ru(2)Zn][PF(6)](2) ([5][PF(6)](2)). The influence of the second metal with regard to the photophysical and electrochemical properties of the ruthenium bis(diimine)X(2) subunit was then investigated. In the case of Ru(II)-Mn(III) heterodinuclear complexes, a partial quenching of the luminescence was observed as a consequence of an efficient electron transfer process from the ruthenium to the manganese. EPR and spectrophotometric analyses of the oxidized species resulting from the one-electron oxidation of compounds [3](2+) and [4](2+) showed the formation of a Mn(IV) species for [3](2+) and an organic free radical for [4](2+). PMID:20485756

Guillo, Pascal; Hamelin, Olivier; Loiseau, Frédérique; Pécaut, Jacques; Ménage, Stéphane

2010-05-18

281

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

282

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

283

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

284

Synthesis, spectroscopic characterization, DNA interaction and antibacterial study of metal complexes of tetraazamacrocyclic Schiff base  

NASA Astrophysics Data System (ADS)

The template condensation reaction between benzil and 3,4-diaminotoulene resulted mononuclear 12-membered tetraimine macrocyclic complexes of the type, [MLCl2] [M = Co(II), Ni(II), Cu(II) and Zn(II)]. The synthesized complexes have been characterized on the basis of the results of elemental analysis, molar conductance, magnetic susceptibility measurements and spectroscopic studies viz. FT-IR, 1H and 13C NMR, FAB mass, UV-vis and EPR. An octahedral geometry has been envisaged for all these complexes, while a distorted octahedral geometry has been noticed for Cu(II) complex. Low conductivity data of all these complexes suggest their non-ionic nature. The interactive studies of these complexes with calf thymus DNA showed that the complexes are avid binders of calf thymus DNA. The in vitro antibacterial studies of these complexes screened against pathogenic bacteria proved them as growth inhibiting agents.

Shakir, Mohammad; Khanam, Sadiqa; Firdaus, Farha; Latif, Abdul; Aatif, Mohammad; Al-Resayes, Saud I.

285

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

286

Photo- and electroluminescent properties of zinc(II) complexes with tetradentate Schiff bases, derivatives of salicylic aldehyde  

NASA Astrophysics Data System (ADS)

It is studied how the introduction of various substituents into the composition of organic ligands affects the photoluminescence spectra of new zinc(II) complexes with tetradentate Schiff bases H2L (derivatives of salicylic aldehyde (H2SAL1, H2SAL2) and o-vanillin (H2MO1, H2MO2) with ethylenediamine and o-phenylenediamine) in the form of bulk solids and thin films. It is demonstrated that the emission spectra of bulk solid complexes without o-phenylenediamine bridges (ZnSAL1 and ZnMO1) contain additional long-wavelength bands compared to the spectra of corresponding thin films. In the case of films obtained from [ZnSAL1]2 dimer complexes, the long-wavelength band is dominant. At the same time, the photoluminescence spectra of ZnSAL2 and ZnMO2 complexes with o-phenylenediamine bridges are similar in the case of solid samples and thin films. The electroluminescent properties of organic light-emitting diodes (OLEDs) with the ITO/?-NPD/ZnL/Ca:Al structure are studied. The bathochromic shift of the electroluminescence peaks of OLEDs with respect to the photoluminescence spectra of bulk solid samples and thin films is probably related to the formation of exciplexes at the ?-NPD/ZnL interface. The electroluminescence spectra of OLEDs based on [ZnSAL1]2 show a hypsochromic shift of the emission maximum, which can be caused by a shift of the recombination region into the ?-NPD layer.

Vashchenko, A. A.; Lepnev, L. S.; Vitukhnovskii, A. G.; Kotova, O. V.; Eliseeva, S. V.; Kuz'mina, N. P.

2010-03-01

287

Hydrogen Bond-Induced Assembly and Crystal Structures of Two Oxovanadium Complexes with Schiff Bases  

Microsoft Academic Search

Two new oxovanadium complexes, [VOL(acac)] (1) and [VO2L]2 (2), where acac is acetylacetone, and L and L are the deprotonated forms of 2-bromo-4-chloro-6-[(2-dimethylaminoethylimino)methyl]phenol (HL) and 2-bromo-4-chloro-6-[(2-methylaminoethylimino)methyl]phenol (HL), respectively, have been synthesized and characterized by infrared (IR) spectra and single-crystal x-ray diffraction. Complex (1) is a mononuclear oxovanadium(IV) complex. Complex (2) is a centrosymmetric dinuclear dioxovanadium(V) complex, with the V···V distance

Shi-Yong Liu; Yu-Ping Ma

2011-01-01

288

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

289

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

290

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

291

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

292

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

293

Non-innocent ligand behavior of a bimetallic Ni Schiff-base complex containing a bridging catecholate.  

PubMed

The geometric and electronic structure of a bimetallic Ni Schiff-base complex and its one-electron oxidized form have been investigated in the solid state and in solution. The two salen units in the neutral complex 1 are linked via a bridging catecholate function. The one-electron oxidized form [1](+) was determined to exist as a ligand radical species in solution, with the electron hole potentially localized on the redox-active dioxolene, the phenolate ligands, or delocalized over the entire ligand system. Electrochemical experiments and UV-vis-NIR spectroscopy, in combination with density functional theory (DFT) calculations, provide insight into the locus of oxidation and the degree of delocalization in this system. The one-electron hole for [1](+) was determined experimentally to be localized on the dioxolene bridge with a small amount of spin density on the outer phenolate moieties predicted by the calculations. The resonance Raman spectrum of [1](+) (?(ex) = 413 nm) in CH(2)Cl(2) solution clearly exhibited a new band at 1315 cm(-1) in comparison to 1, which is predicted to be a combination of dioxolene ring and C-O bond stretching modes, consistent with oxidation of the bridging moiety in [1](+). Analysis of the NIR bands for [1](+), in association with time-dependent DFT calculations, suggests that the low energy bands are ligand to ligand charge transfer transitions from the terminal phenolates to the central dioxolene unit. In combination, this data is consistent with a description of the overall electronic structure of [1](+) as a bridge-localized semiquinone ligand radical species. This is in contrast to the mixed-valence ground state description for many one-electron oxidized Ni salen monomer systems, and analysis in terms of intervalence charge transfer (IVCT) theory. PMID:21675708

Dunn, Tim J; Ramogida, Caterina F; Simmonds, Curtis; Paterson, Alisa; Wong, Edwin W Y; Chiang, Linus; Shimazaki, Yuichi; Storr, Tim

2011-06-15

294

Ferrocenyl-substituted Schiff base complexes of boron: synthesis, structural, physico-chemical and biochemical aspects.  

PubMed

Biological important complexes of boron(III) derived from 1-acetylferrocenehydrazinecarboxamide (L1H), 1-acetylferrocenehydrazinecarbothioamide (L2H) and 1-acetylferrocene carbodithioic acid (L3H) have been prepared and investigated using a combination of microanalytical analysis, melting point, electronic, IR, 1H NMR and 13C NMR spectral studies, cyclic voltammetry and X-ray powder diffraction studies. Boron isopropoxide interacts with the ligands in 1:1, 1:2 and 1:3 molar ratios (boron:ligand) resulting in the formation of coloured products. On the basis of conductance and spectral evidences, tetrahedral structures for boron(III) complexes have been assigned. The ligands are coordinated to the boron(III) via the azomethine nitrogen atom and the thiolic sulfur atom/enolic oxygen atom. On the basis of X-ray powder diffraction study one of the representative boron complex was found to have orthorhombic lattice, having lattice parameters: a=9.9700, b=15.0000 and c=7.0000. Both the ligands and their complexes have been screened for their biological activity on several pathogenic fungi and bacteria and were found to possess appreciable fungicidal and bactericidal properties. Plant growth regulating activity of one of the ligand and its complexes has also been recorded on gram plant, and results have been discussed. PMID:21167770

Yadav, Sunita; Singh, R V

2010-12-16

295

New Benzo-15Crown5 Ethers Featuring Salicylic Schiff Base Substitutions – Synthesis, Complexes and Structural Study  

Microsoft Academic Search

Condensation reactions between 4'-formyl-5'-hydroxybenzo-15-crown-5and 2-aminopyridine, 2-amino-6-methylpyridine, 2-amino-4-methylpyridine or2-(aminomethyl)furan yielded the new laterally functionalized crown ethers1–4. The crown compounds 1–3 form crystalline 1:1 (Na+:ligand) complexes 1a–3a with sodium perchlorate. Ligands and complexes have been characterized by elemental analyses, IR, UV-Vis, 1H-, 13C-NMR and mass spectra. The tautomeric equilibria (phenol-imine, O...H–N and keto-amine, O...H–N forms) have been systematically studied by using UV-Vis

Zeliha Hayvali; Mustafa Hayvali; Zeynel Kiliç; Tuncer Hökelek; Edwin Weber

2003-01-01

296

Crystal structure and antitumor activity of some rare earth metal complexes with Schiff base  

Microsoft Academic Search

The ligand 1-phenyl-3-methyl-5-hydroxy-4-pyrazolyl phenyl ketone (PMBP) isonicotinoyl hydrazone (H2L) was prepared by condensation of PMBP with isoniazid. Seven complexes of rare earth metals with H2L were synthesized and characterized on the basis of elemental analyses, IR, UV, 1H NMR spectra and thermal analyses. The general formula of the complexes is Ln(HL)3·3.5H2O (where Ln(III)=La, Eu, Gd, Tb, Dy, Ho and Er).

Zheng-Yin Yang; Ru-Dong Yang; Fa-Shen Li; Kai-Bei Yu

2000-01-01

297

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

298

Hydroxy- and alkoxy-bridged dinuclear uranyl-Schiff base complexes: hydrolysis, transamination and extraction studies.  

PubMed

The reaction of uranyl nitrate with 1,3-bis(salicylideneamino)-2-propanol (H(3)L1) and 1,3-bis(3,5-di-tert-butylsalicylideneamino)-2-propanol (H(3)L2) in the presence of triethylamine (Et(3)N) yielded hydroxy- and alkoxy-bridged dinuclear complexes; [(UO(2))(2)(L1)(OH)(MeOH)(2)].(MeOH)(2) (.(MeOH)(2)) and [(UO(2))(2)(L2)(OH)(MeOH)(2)].(MeOH)(2) (.(MeOH)(2)). The crystal structures of .(DMF)(2) and .(DMF)(2) exhibit an unsymmetrical central U(2)O(2) core involving bridging alkoxy- and hydroxy-oxygen atoms. The geometry around the uranium center in .(DMF)(2) and .(DMF)(2) is that of a distorted pentagonal bipyramid with the solvent molecule occupying the fifth coordination site. The flexible nature of the ligand backbone is more pronounced in .(DMF)(2) compared to .(DMF)(2), yielding two molecules per unit cell in different conformations. Under similar reaction conditions, using ethylenediamine as a base, the respective Salen-based uranyl compounds, [UO(2)(Salen)(MeOH)] () and [UO(2)(Bu(t)(2)-Salen)(MeOH)] () are obtained due to transamination of the ligand backbone. Complexes .(MeOH)(2) and .(MeOH)(2) when reacted with an excess of ethylenediamine failed to yield the respective Salen-based complexes, and , respectively. The new compounds have been characterized using solution (NMR and UV-Vis) and solid-state (IR, X-ray crystallography) techniques. Hydrolysis of .(MeOH)(2) and .(MeOH)(2) in the pH range 1-14 was studied using UV-Vis spectroscopy and compared with the hydrolysis of and [UO(2)(Salophen)(MeOH)] (). A two-phase extraction study suggests quantitative removal of uranyl ions from the aqueous phase at higher pH conditions. PMID:18493632

Bharara, Mohan S; Heflin, Kathryn; Tonks, Stephen; Strawbridge, Kara L; Gorden, Anne E V

2008-04-29

299

Room temperature polymerization of alkyl isocyanates catalyzed by rare earth Schiff base complexes  

Microsoft Academic Search

The polymerization of alkyl isocyanates catalyzed by rare earth chloride salen complexes\\/triisobutyl aluminum (Ln(H2salen)2Cl3·2C2H7OH\\/Al(i-Bu)3) at room temperature was investigated. The influences of ligand structure, catalyst composition, polymerization temperature,\\u000a polymerization time, the concentration of catalyst and monomer, and the polymerization solvent on the polymerization of isocyanates\\u000a were studied. It was found that under the polymerization conditions, examined La(H2salenA)2Cl3·2C2-H7OH\\/Al(i-Bu)3 (H2salenA= N,N?-disalicylideneethylene diamine)

XiongFa Yang; XuFeng Ni; ZhiQuan Shen

2009-01-01

300

Spectroscopic, in vitro antibacterial, and antifungal studies of Co(II), Ni(II), and Cu(II) complexes with 4-chloro-3-coumarinaldehyde Schiff bases  

Microsoft Academic Search

A series of metal complexes ML2?·?2H2O [M?=?Co(II), Ni(II), and Cu(II)] have been synthesized with Schiff bases derived from 3-substituted-4-amino-5-mercapto-1,2,4-triazole and 4-chloro-3-coumarinaldehyde. The structures of these metal complexes have been proposed from elemental analyses, spectral (IR, UV-Vis, FAB-mass, ESR, and fluorescence), magnetic, and thermal studies. Low molar conductance values in DMF indicate that the metal complexes are non-electrolytes. Cyclic voltammetric studies

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

2011-01-01

301

Synthesis, characterization, DNA cleavage, and in-vitro antimicrobial studies of Co(II), Ni(II), and Cu(II) complexes with Schiff bases of coumarin derivatives  

Microsoft Academic Search

A series of Co(II), Ni(II), and Cu(II) complexes ML?·?3H2O have been synthesized with Schiff bases derived from 3-substituted-4-amino-5-mercapto-1,2,4-triazole and 5-formyl-6-hydroxy coumarin. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMF indicate that the complexes are non-electrolytes. In view of analytical, spectral (infrared, UV-Vis, ESR, TG, and FAB-mass), and

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

2011-01-01

302

Asymmetric catalytic epoxidation of styrene by dissymmetric Mn(III) and Ru(III) chiral Schiff base complexes synthesis and physicochemical studies  

Microsoft Academic Search

Some dissymmetric Mn(III) and Ru(III) chiral Schiff base complexes derived from 1R,2R(?)1,2-diaminocyclohexane with 3-acetyl-4-hydroxy-6-methyl-2-pyrone and salicylaldehyde, 5-chloro-5-methoxy-and 5-nitrosalicylaldehyde have been synthesized. The characterization of the complexes was accomplished by microanalysis, IR, UV-Vis, CD spectroscopy, conductance measurements, magnetic susceptibility, optical rotation and electrochemical studies. The asymmetric epoxidations catalyzed by the complexes were examined with styrene using the terminal oxidant, iodosylbenzene to

R. I. Kureshy; N. H. Khan; S. H. R. Abdi; A. K. Bhatt

1996-01-01

303

Synthesis, structural elucidation, electro-chemical behaviour and fungitoxic activity of transition metal(II) mixed-ligand complexes with some Schiff bases  

Microsoft Academic Search

The Schiff bases, potassium salt of salicylidene-?-alanine [KHL], bis(benzylidene)ethylenediamine [SB] and thiophene-o-carboxaldene-p-toluidine [SB], and mixed-ligand complexes with Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) have been prepared. They were characterized by elemental analyses, magnetic susceptibility measurements, thermogravimetric analyses (t.g.a.), infrared spectra and electronic spectra. The mixed-ligand complexes were found to have the general composition [M(L)(SB)(H2O)]. All the mixed-ligand complexes were

Hitesh M. Parekh; Mohan N. Patel

2005-01-01

304

SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION, REDOX, AND BIOLOGICAL SCREENING STUDIES OF SOME SCHIFF BASE TRANSITION METAL(II) COMPLEXES DERIVED FROM SALICYLIDENE-4AMINOANTIPYRINE AND 2AMINOPHENOL\\/ 2-AMINOTHIOPHENOL  

Microsoft Academic Search

Neutral complexes of Cu(II), Ni(II), Co(II), Mn(II), VO(IV) and Zn(II) have been synthesised from the Schiff bases derived from salicylidene-4-aminoantipyrine and 2-aminophenol\\/2-aminothiophenol. The structural features have been arrived at from their microanalytical, IR, UV-Vis., H NMR and ESR spectral data. All of the complexes exhibit square-planar geometry except the Mn(II) and VO(IV) complexes. The Mn(II) chelates show an octahedral environment

N. Raman; A. Kulandaisamy; K. Jeyasubramanian

2001-01-01

305

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

306

Design, characterization, teratogenicity testing, antibacterial, antifungal and DNA interaction of few high spin Fe(II) Schiff base amino acid complexes  

NASA Astrophysics Data System (ADS)

In this study, new Fe(II) Schiff base amino acid chelates derived from the condensation of o-hydroxynaphthaldehyde with L-alanine, L-phenylalanine, L-aspartic acid, L-histidine and L-arginine were synthesized and characterized via elemental, thermogravimetric analysis, molar conductance, IR, electronic, mass spectra and magnetic moment measurements. The stoichiometry and the stability constants of the complexes were determined spectrophotometrically. Correlation of all spectroscopic data suggested that Schiff bases ligands exhibited tridentate with ONO sites coordinating to the metal ions via protonated phenolic-OH, azomethine-N and carboxylate-O with the general formulae [Fe(HL)2]·nH2O. But in case of L-histidine, the ligand acts as tetradentate via deprotonated phenolic-OH, azomethine-N, carboxylate-O and N-imidazole ring ([FeL(H2O)2]·2H2O), where HL = mono anion and L = dianion of the ligand. The structure of the prepared complexes is suggested to be octahedral. The prepared complexes were tested for their teratogenicity on chick embryos and found to be safe until a concentration of 100 ?g/egg with full embryos formation. Moreover, the interaction between CT-DNA and the investigated complexes were followed by spectrophotometric and viscosity measurements. It was found that, the prepared complexes bind to DNA via classical intercalative mode and showed a different DNA activity with the sequence: nhi > nari > nali > nasi > nphali. Furthermore, the free ligands and their complexes are screened for their in vitro antibacterial and antifungal activity against three types of bacteria, Escherichia coli, Pseudomonas aeruginosa and Bacillus cereus and three types of anti fungal cultures, Penicillium purpurogenium, Aspergillus flavus and Trichotheium rosium in order to assess their antimicrobial potential. The results show that the metal complexes are more reactive with respect to their corresponding Schiff base amino acid ligands.

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

2013-07-01

307

A new trinuclear zinc(II) complex and a heptacoordinated mononuclear cadmium(II) complex with a pyrimidine derived Schiff base ligand: Syntheses, crystal structures, photoluminescence and DFT calculations  

NASA Astrophysics Data System (ADS)

A new pyrimidine derived Schiff Base ligand (L) was synthesized.One zinc (1) and one cadmium (2) complexes have been synthesized and characterized.The geometries of both complexes were optimised in the singlet state by DFT method.TDDFT calculations have been performed.Complex 1 exhibits intraligand 1(????) fluorescence.

Das, Kinsuk; Jana, Atanu; Konar, Saugata; Chatterjee, Sudipta; Mondal, Tapan Kumar; Barik, Anil Kumar; Kar, Susanta Kumar

2013-09-01

308

Synthesis, electrochemical, magnetic, catalytic and antimicrobial studies of N-functionalized cyclam based trinuclear copper(II) and nickel(II) complexes  

Microsoft Academic Search

Trinuclear copper(II) and nickel(II) complexes have been prepared by using Schiff base ligands derived from 1,8-[bis(3-formyl-2-hydroxy-5-methyl)\\u000a benzyl]-4,11-dimethyl-l,4,8,11-tetraazacyclotetradecane, and 1,8-[bis(3-formyl-2-hydroxy-5-bromo)benzyl]-4,11-dimethyl-l,4,8,11-tetraazacyclotetradecane\\u000a with aliphatic and aromatic diamines. All the complexes were characterized by elemental and spectroscopic analysis. Electrochemical\\u000a studies of the copper(II) complexes in DMF solution show three irreversible one electron reduction process around Epc 1= ?0.59 to ?0.80 V, Epc 2= ?0.89 to ?1.14 V and Epc 3= ?1.17 to

S. Sreedaran; K. Shanmuga Bharathi; A. Kalilur Rahiman; L. Jagadish; V. Kaviyarasan; V. Narayanan

2010-01-01

309

SNO donor Schiff bases and their Co(II), Ni(II) and Cu(II) complexes: synthesis, characterization, electrochemical and antimicrobial studies  

Microsoft Academic Search

A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized with newly synthesized Schiff bases derived from 3-substituted-4-amino-5-mercapto-1,2,4-triazole and isatin. The elemental analyses of the complexes are confined to the stoichiometry of the type ML2 [M=Co(II), Ni(II) and Cu(II)], respectively, where L acts as a deprotonated ligand in which sulfur plays an important role in coordination. In view of

Ajaykumar D. Kulkarni; Sangamesh A. Patil; Prema S. Badami

2009-01-01

310

Spectral characterization of novel ternary zinc(II) complexes containing 1,10-phenanthroline and Schiff bases derived from amino acids and salicylaldehyde-5-sulfonates  

Microsoft Academic Search

A series of new ternary zinc(II) complexes [Zn(L1–10)(phen)], where phen is 1,10-phenanthroline and H2L1–10=tridentate Schiff base ligands derived from the condensation of amino acids (glycine, l-phenylalanine, l-valine, l-alanine, and l-leucine) and salicylaldehyde-5-sulfonates (sodium salicylaldehyde-5-sulfonate and sodium 3-methoxy-salicylaldehyde-5-sulfonate), have been synthesized. The complexes were characterized by elemental analysis, IR, UV–vis, 1H NMR, and 13C NMR spectra. The IR spectra of the

Davar M. Boghaei; Mehrnaz Gharagozlou

2007-01-01

311

Spectroscopic studies of bimetallic complexes derived from tridentate or tetradentate Schiff bases of some di- and tri-valent transition metals  

Microsoft Academic Search

Two series of new binuclear complexes with Schiff base ligands, H4La or H2Lb, derived from the reaction of 4,6-diacetylresorcinol and ethylenediamine, in the molar ratio 1:1 and 1:2 have been prepared, respectively. The two ligands react with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Cr(III) and Fe(III)-nitrates to get binuclear complexes. The ligands were characterized by elemental analysis, IR, UV–vis, 1H NMR

Adel A. A. Emara; Azza A. A. Abou-Hussen

2006-01-01

312

Square planar complexes of Cu(II) and Ni(II) with N 2 O donor set of two Schiff base ligands: synthesis and structural aspects  

Microsoft Academic Search

\\u000a Abstract  Two new square planar Cu(II) and Ni(II) complexes, [CuL1(NCO)] (1) and [NiL2(N3)] (2) have been synthesized with two different tridentate N2O donor Schiff base ligands L\\u000a \\u000a 1\\u000a \\u000a H (1:1 condensation product of benzoylacetone and 2-diethylaminoethylamine) and L\\u000a \\u000a 2\\u000a \\u000a H (1:1 condensation product of benzoylacetone and 2-dimethylaminoethylamine), respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR,

Subhra Basak; Soma Sen; Samiran Mitra; C. Marschner; W. S. Sheldrick

2008-01-01

313

Synthesis, structures and fluorescence of nickel, zinc and cadmium complexes with the N,N,O-tridentate Schiff base N-2-pyridylmethylidene-2-hydroxy-phenylamine  

Microsoft Academic Search

Mono-, tri- and dinuclear neutral complexes [Ni(HL)(L)]·(ClO4)·0.16(H2O) (1), [ZnLZn(OOCCH3)4ZnL] (2) and [Cd2L2(OCH3CO)2(H2O)2] (3) have been obtained from the reaction between the potentially tridentate N,N,O-donor Schiff base ligand HL, where HL=N-2-pyridylmethylidene-2-hydroxy-phenylamine with nickel, zinc or cadmium salts, respectively. The ligand has been prepared by 1:1 condensation of pyridine-2-carboxaldehyde and 2-aminophenol. The ligand and metal complexes were characterised by elemental analysis, spectroscopic

Arpi Majumder; Georgina M. Rosair; Arabinda Mallick; Nitin Chattopadhyay; Samiran Mitra

2006-01-01

314

Metal-pyrazolyl diazine interaction: Synthesis, structure and electrochemistry of binuclear transition metal(II) complexes derived from an `end-off' compartmental Schiff base ligand  

NASA Astrophysics Data System (ADS)

Pyrazolyl diazine (?-NN) bridged late first row transition metal(II) complexes have been prepared by the interaction of metal(II) chlorides with an 'end-off' compartmental Schiff base ligand. The ligand system has a strong diazine bridging component and obtained as a condensation product between 1 H-pyrazole-3,5-dicarbohydrazide and 3-acetylcoumarin in absolute ethanol. All synthesized compounds are characterized on the basis of various spectral and analytical techniques. Complexes are found to be non-electrolytes and monomeric in nature. The magnetic exchange interactions are very weak because of the more electronegative exogenous chloride, though diazine bridging group bring metal centers in a close proximity.

Budagumpi, Srinivasa; Revankar, Vidyanand K.

2010-09-01

315

Synthesis, crystal structures and magnetic studies of dicyanamide bridged two new 1D copper(II) complexes  

Microsoft Academic Search

Two new dicyanamide bridged 1D polynuclear copper(II) complexes [Cu(L1){?1,5-N(CN)2}]n (1) [L1H=C6H5C(O)NHNC(CH3)C5H4N] and [Cu(L2){?1,5-N(CN)2}]n (2) [L2H=C6H5C(O)CHC(CH3)NCH2CH2N(CH3)2] have been synthesised and structures of both the complexes and their crystal packing arrangements have been established by X-ray crystallography. For complex 1, a tridentate hydrazone ligand (L1H) obtained by the condensation of benzhydrazide and 2-acetylpyridine is used, whereas a tridentate Schiff base (L2H) derived

Soma Sen; Samiran Mitra; David L. Hughes; Georgina Rosair; Cédric Desplanches

2007-01-01

316

Ru(II) complexes of N 4 and N 2O 2 macrocyclic Schiff base ligands: Their antibacterial and antifungal studies  

NASA Astrophysics Data System (ADS)

Reactions of [RuCl 2(DMSO) 4] with some of the biologically active macrocyclic Schiff base ligands containing N 4 and N 2O 2 donor group yielded a number of stable complexes, effecting complete displacement of DMSO groups from the complex. The interaction of tetradentate ligand with [RuCl 2(DMSO) 4] gave neutral complexes of the type [RuCl 2(L)] [where L = tetradentate macrocyclic ligand]. These complexes were characterized by elemental, IR, 1H, 13C NMR, mass, electronic, thermal, molar conductance and magnetic susceptibility measurements. An octahedral geometry has been proposed for all complexes. All the macrocycles and macrocyclic Ru(II) complexes along with existing antibacterial drugs were screened for antibacterial activity against Gram +ve ( Bacillus subtilis, Staphylococcus aureus) and Gram -ve ( Escherichia coli, Klebsiella pneumonia) bacteria. All these compounds were found to be more active when compared to streptomycin and ampicillin. The representative macrocyclic Schiff bases and their complexes were also tested in vitro to evaluate their activity against fungi, namely, Aspergillus flavus and Fusarium species.

Shanker, Kanne; Rohini, Rondla; Ravinder, Vadde; Reddy, P. Muralidhar; Ho, Yen-Peng

2009-07-01

317

Synthesis of electron-rich uranium(IV) complexes supported by tridentate Schiff base ligands and their multi-electron redox chemistry.  

PubMed

The synthesis, structure, and reactivity of a new complex of U(IV) with the tridentate Schiff base ligand Menaphtquinolen are reported. The reduction of the bis-ligand complexes [UX2((Me)naphtquinolen)2] (X = Cl, (1-Cl) ; I (1-I)) with potassium metal affords the U(IV) complex of the new tetranionic hexadentate ligand ?-bis-(Me)naphtquinolen formed through the intramolecular reductive coupling of the imino groups of each (Me)naphtquinolen unit. The solid state structure of the [U(?-bis-(Me)naphtquinolen)]2 dimer 2 isolated from toluene confirms the presence of a U(IV) complex of the reduced ligand. Reactivity studies with molecular oxygen and 9,10-phenanthrenequinone show that complex 2 can act as a multielectron reducing agent releasing two electrons through the cleavage of the C-C bond to restore the original imino function of the ligand. In the resulting U(IV) and U(VI) complexes [U(9,10-phenanthrenediol)((Me)naphtquinolen)2], 3, and [UO2((Me)naphtquinolen)2], 4, the restored tridentate Schiff base allows for the coordination of the reduced substrate to the metal. Electrochemical studies of complex 2 show the presence of irreversible ligand centered reduction processes and of a reversible U(IV)/U(III) couple. PMID:23734761

Camp, Clément; Andrez, Julie; Pécaut, Jacques; Mazzanti, Marinella

2013-06-04

318

Ru(II) complexes of N4 and N2O2 macrocyclic Schiff base ligands: their antibacterial and antifungal studies.  

PubMed

Reactions of [RuCl2(DMSO)4] with some of the biologically active macrocyclic Schiff base ligands containing N4 and N2O2 donor group yielded a number of stable complexes, effecting complete displacement of DMSO groups from the complex. The interaction of tetradentate ligand with [RuCl2(DMSO)4] gave neutral complexes of the type [RuCl2(L)] [where L=tetradentate macrocyclic ligand]. These complexes were characterized by elemental, IR, 1H, 13C NMR, mass, electronic, thermal, molar conductance and magnetic susceptibility measurements. An octahedral geometry has been proposed for all complexes. All the macrocycles and macrocyclic Ru(II) complexes along with existing antibacterial drugs were screened for antibacterial activity against Gram +ve (Bacillus subtilis, Staphylococcus aureus) and Gram -ve (Escherichia coli, Klebsiella pneumonia) bacteria. All these compounds were found to be more active when compared to streptomycin and ampicillin. The representative macrocyclic Schiff bases and their complexes were also tested in vitro to evaluate their activity against fungi, namely, Aspergillus flavus and Fusarium species. PMID:19268628

Shanker, Kanne; Rohini, Rondla; Ravinder, Vadde; Reddy, P Muralidhar; Ho, Yen-Peng

2009-01-31

319

Synthesis, spectroscopic and catalytic studies of Cu(II), Co(II) and Ni(II) complexes immobilized on Schiff base modified chitosan  

NASA Astrophysics Data System (ADS)

A new class of bidentate (N, O) Schiff base ligand (L) has been derived from the functional biopolymer (chitosan) and 1,2-diphenylethanedione in 1:1 M ratio. This ligand has been used to synthesise the new first row transition metal complexes of Cu(II), Co(II) and Ni(II). The structural properties of the ligand and the synthesized tetra-coordinated complexes have been investigated by elemental analysis, magnetic study, molar conductance measurement and spectroscopic methods viz. FT-IR, UV-Vis., 1H NMR, 13C NMR and XRD. The spectral evidences strongly suggested the square planar geometry to the complexes. The XRD studies proved that crystallinity of chitosan has been diminished after Schiff base formation and metal complexation of L. Thermal and surface properties of the complexes have been also discussed from the investigation of their TG-DTG curves and SEM images, respectively. In addition, the catalytic efficiency of these complexes has been studied in the cyclohexane oxidation reaction using H2O2 as oxidant at 70 °C.

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

2013-10-01

320

Synthesis, crystal structure and interaction of L-valine Schiff base divanadium(V) complex containing a V2O3 core with DNA and BSA.  

PubMed

A divanadium(V) complex, [V2O3(o-van-val)2] (o-van-val=Schiff base derived from o-vanillin and L-valine), has been synthesized and structurally characterized. The crystal structure shows that both of the vanadium centers in the complex have a distorted octahedral coordination environment composed of tridentate Schiff base ligand. A V2O3 core in molecular structure adopts intermediate between cis and trans configuration with the O1V1?V1AO1A torsion angle 115.22 (28)° and the V1?V1A distance 3.455Å. The binding properties of the complex with calf thymus DNA (CT-DNA) have been investigated by UV-vis absorption, fluorescence, CD spectra and viscosity measurement. The results indicate that the complex binds to CT-DNA in non-classical intercalative mode. Meanwhile, the interaction of the complex with bovine serum albumin (BSA) has been studied by UV-vis absorption, fluorescence and CD spectra. Results indicated that the complex can markedly quench the intrinsic fluorescence of BSA via a static quenching process, and cause its conformational change. The calculated apparent binding constant Kb was 1.05×10(6)M(-1) and the binding site number n was 1.18. PMID:23376270

Guo, Qiong; Li, Lianzhi; Dong, Jianfang; Liu, Hongyan; Xu, Tao; Li, Jinghong

2013-01-10

321

Synthesis, crystal structure and interaction of L-valine Schiff base divanadium(V) complex containing a V2O3 core with DNA and BSA  

NASA Astrophysics Data System (ADS)

A divanadium(V) complex, [V2O3(o-van-val)2] (o-van-val = Schiff base derived from o-vanillin and L-valine), has been synthesized and structurally characterized. The crystal structure shows that both of the vanadium centers in the complex have a distorted octahedral coordination environment composed of tridentate Schiff base ligand. A V2O3 core in molecular structure adopts intermediate between cis and trans configuration with the O1dbnd V1⋯V1Adbnd O1A torsion angle 115.22 (28)° and the V1⋯V1A distance 3.455 Å. The binding properties of the complex with calf thymus DNA (CT-DNA) have been investigated by UV-vis absorption, fluorescence, CD spectra and viscosity measurement. The results indicate that the complex binds to CT-DNA in non-classical intercalative mode. Meanwhile, the interaction of the complex with bovine serum albumin (BSA) has been studied by UV-vis absorption, fluorescence and CD spectra. Results indicated that the complex can markedly quench the intrinsic fluorescence of BSA via a static quenching process, and cause its conformational change. The calculated apparent binding constant Kb was 1.05 × 106 M-1 and the binding site number n was 1.18.

Guo, Qiong; Li, Lianzhi; Dong, Jianfang; Liu, Hongyan; Xu, Tao; Li, Jinghong

2013-04-01

322

DNA cleavage, antimicrobial, spectroscopic and fluorescence studies of Co(II), Ni(II) and Cu(II) complexes with SNO donor coumarin Schiff bases.  

PubMed

A series of Co(II), Ni(II) and Cu(II) complexes of the type ML(2) have been synthesized with Schiff bases derived from methylthiosemicarbazone and 5-formyl-6-hydroxy coumarin/8-formyl-7-Hydroxy-4-methylcoumarin. The complexes are insoluble in common organic solvents but soluble in DMF and DMSO. The measured molar conductance values in DMF indicate that, the complexes are non-electrolytes in nature. In view of analytical, spectral (IR, UV-vis, ESR, FAB-mass and fluorescence), magnetic and thermal studies, it has been concluded that, all the metal complexes possess octahedral geometry in which ligand is coordinated to metal ion through azomethine nitrogen, thione sulphur and phenolic oxygen atom via deprotonation. The redox behavior of the metal complexes was investigated by using cyclic voltammetry. The Schiff bases and their complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi) and antifungal activities (Aspergillus niger, Aspergillus flavus and Cladosporium) by Minimum Inhibitory Concentration method. The DNA cleavage is studied by agarose gel electrophoresis method. PMID:19962341

Patil, Sangamesh A; Naik, Vinod H; Kulkarni, Ajaykumar D; Badami, Prema S

2009-11-05

323

DNA interaction, antimicrobial, electrochemical and spectroscopic studies of metal(II) complexes with tridentate heterocyclic Schiff base derived from 2?-methylacetoacetanilide  

NASA Astrophysics Data System (ADS)

A new Schiff base ligand (HL) was synthesized by the condensation reaction between 2?-methyleacetoacetanilide and 2-amino-3-hydroxypyridine. Its Co(II), Ni(II), Cu(II) and Zn(II) complexes were prepared by the interaction of the ligand with metal(II) chloride. They were characterized by elemental analysis, IR, 1H NMR, EPR, UV-Vis, magnetic susceptibility measurements, conductivity measurements and FAB-mass spectra. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by UV absorption, viscosity and cyclic voltammetry methods, and the mode of CT-DNA binding to the complexes has been explored. Furthermore, the DNA cleavage activity by the complexes was performed. It was found to be oxidative hydroxyl radical cleavage in the presence of 3-mercaptopropionic acid (MPA). The Schiff base and its complexes have been screened for their antibacterial (Staphylococcus aureus, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Rhizopus stolonifer, Rhizoctonia bataicola and Candida albicans) activities and the data reveal that the complexes have higher activity than the free ligand.

Raman, Natarajan; Pothiraj, Krishnan; Baskaran, Thanasekaran

2011-08-01

324

Spectroscopic Characterization and Biological Activity of Mixed Ligand Complexes of Ni(II) with 1,10-Phenanthroline and Heterocyclic Schiff Bases  

PubMed Central

Mixed ligand complexes of Ni(II) with 1,10-phenanthroline (1,10-Phen) and Schiff bases L1(MIIMP); L2(CMIIMP); L3(EMIIMP); L4(MIIMNP); L5(MEMIIMP); L6(BMIIMP); L7(MMIIMP); L8(MIIBD) have been synthesized. These metal chelates have been characterized by elemental analysis, IR, 1H-NMR, 13C-NMR, Mass, UV-Vis, magnetic moments, and thermogravimetric (TG&DTA) analysis. Spectral data showed that the 1,10-phenanthroline act as neutral bidentate ligand coordinating to the metal ion through two nitrogen donor atoms and Schiff bases acts as monobasic bidentate coordinating through NO donor atoms. All Ni(II) complexes appear to have an octahedral geometry. The antimicrobial activity of mixed ligand complexes has been studied by screening against various microorganisms, it is observed that the activity enhances upon coordination. The DNA binding studies have been investigated by UV-Vis spectroscopy, and the experimental results indicate that these complexes bind to CT DNA with the intrinsic binding constant Kb = 2.5 ± 0.2 × 105?M?1. MTT is used to test the anticancer effect of the complexes with HL60 tumor cell. The inhibition ratio was accelerated by increasing the dosage, and it had significant positive correlation with the medication dosage.

Prashanthi, Y.; Kiranmai, K.; Ira; K, Sathish kumar; Chityala, Vijay kumar; Shivaraj

2012-01-01

325

Structural, spectral and biological studies of binuclear tetradentate metal complexes of N 3O Schiff base ligand synthesized from 4,6-diacetylresorcinol and diethylenetriamine  

NASA Astrophysics Data System (ADS)

The binuclear Schiff base, H 2L, ligand was synthesized by reaction of 4,6-diacetylresorcinol with diethylenetriamine in the molar ratio 1:2. The coordination behavior of the H 2L towards Cu(II), Ni(II), Co(II), Zn(II), Fe(III), Cr(III), VO(IV) and UO 2(VI) ions has been investigated. The elemental analyses, magnetic moments, thermal studies and IR, electronic, 1H NMR, ESR and mass spectra were used to characterize the isolated ligand and its metal complexes. The ligand acts as dibasic with two N 3O-tetradentate sites and can coordinate with two metal ions to form binuclear complexes. The bonding sites are the nitrogen atoms of the azomethine and amine groups and the oxygen atoms of the phenolic groups. The metal complexes exhibit either square planar, tetrahedral, square pyramid or octahedral structures. The Schiff base ligand and its metal complexes were tested against four pathogenic bacteria ( Staphylococcus aureus and Streptococcus pyogenes) as Gram-positive bacteria, and ( Pseudomonas fluorescens and Pseudomonas phaseolicola) as Gram-negative bacteria and two pathogenic fungi ( Fusarium oxysporum and Aspergillus fumigatus) to assess their antimicrobial properties. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms.

Emara, Adel A. A.

2010-09-01

326

New Ru(II)–DMSO complexes of ON\\/SN chelates: Synthesis, behavior of Schiff bases towards hydrolytic cleavage of C N bond, electrochemistry and biological activities  

Microsoft Academic Search

The reaction of cis-[RuCl2(DMSO)4] with salicylaldehyde semicarbazone in ethanol resulted in the chemoselective cleavage of the CN bond of the Schiff base, forming a complex in which the semicarbazide remains coordinated to the metal, as observed previously with trans-[RuCl2(DMSO)4]. In another set of reactions of cis-[RuCl2(DMSO)4] with 4-aminoantipyrine derivatives of salicylaldehyde, 2-hydroxy-1-naphthaldehyde and o-vanillin, CN cleavage was observed in all

Viswanathan Mahalingam; Nataraj Chitrapriya; Frank R. Fronczek; Karuppannan Natarajan

2010-01-01

327

Cu(II) Schiff Base Complex as Highly Efficient Catalyst for the synthesis of Polyhydroquinoline Derivatives via Hantzsch Condensation in Water.  

PubMed

In the present study, we introduce Cu(II) Schiff-base complex as highly efficient and green solid catalyst for the unsymmetrical Hantzsch condensation through a four-components coupling of various aldehydes, dimedone, ethyl acetoacetate and ammonium acetate to form polyhydroquinoline derivatives in good to excellent yields. This reaction has been carried out in the presence of 1 mol% of catalysts in water at room temperature. The reusability of the catalysts was demonstrated by a five-run test. Remarkable features of this new procedure are cleaner reaction pro?les, shorter reaction times, simple experimental and work-up procedures. PMID:23701007

Vahdat, Seyed Mohammad; Golchoubian, Hamid; Mardani, Hamid Reza; Baghery, Saeed

2013-05-20

328

Synthesis, magnetic and spectroscopic studies of a Schiff base derived from cephaclor and 1,2-diaminobenzene and its transition metal complexes  

NASA Astrophysics Data System (ADS)

M(II) coordination compounds of Mn, Fe, Co and Ni with a Schiff base (HL) derived from the condensation of cephaclor antibiotic with 1,2-diaminobenzene were synthesized and characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and 1H NMR spectral studies. The analytical and molar conductance values indicated that the chloride ions coordinate to the metal ions. Based on these studies, the general formulae [M(L)Cl(H2O)] (M(II) = Mn, Fe, Co, Ni) are proposed for the complexes. The ligand HL behaves as a monoanionic tetradentate NNNO chelating agent.

Anacona, Juan; Santaella, Javier

2013-11-01

329

Synthesis, magnetic and spectroscopic studies of a Schiff base derived from cephaclor and 1,2-diaminobenzene and its transition metal complexes.  

PubMed

M(II) coordination compounds of Mn, Fe, Co and Ni with a Schiff base (HL) derived from the condensation of cephaclor antibiotic with 1,2-diaminobenzene were synthesized and characterized by several techniques, including elemental and thermal analysis, molar conductance and magnetic susceptibility measurements, electronic, FT-IR, EPR and (1)H NMR spectral studies. The analytical and molar conductance values indicated that the chloride ions coordinate to the metal ions. Based on these studies, the general formulae [M(L)Cl(H2O)] (M(II)=Mn, Fe, Co, Ni) are proposed for the complexes. The ligand HL behaves as a monoanionic tetradentate NNNO chelating agent. PMID:23892120

Anacona, Juan; Santaella, Javier

2013-07-09

330

Synthesis, spectroscopic and biological activities studies of acyclic and macrocyclic mono and binuclear metal complexes containing a hard-soft Schiff base.  

PubMed

Mono- and bi-nuclear acyclic and macrocyclic complexes with hard-soft Schiff base, H(2)L, ligand derived from the reaction of 4,6-diacetylresorcinol and thiocabohydrazide, in the molar ratio 1:2 have been prepared. The H(2)L ligand reacts with Co(II), Ni(II), Cu(II), Zn(II), Mn(II) and UO(2)(VI) nitrates, VO(IV) sulfate and Ru(III) chloride to get acyclic binuclear complexes except for VO(IV) and Ru(III) which gave acyclic mono-nuclear complexes. Reaction of the acyclic mono-nuclear VO(IV) and Ru(III) complexes with 4,6-diacetylresorcinol afforded the corresponding macrocyclic mono-nuclear VO(IV) and Ru(IIII) complexes. Template reactions of the 4,6-diacetylresorcinol and thiocarbohydrazide with either VO(IV) or Ru(III) salts afforded the macrocyclic binuclear VO(IV) and Ru(III) complexes. The Schiff base, H(2)L, ligand acts as dibasic with two NSO-tridentate sites and can coordinate with two metal ions to form binuclear complexes after the deprotonation of the hydrogen atoms of the phenolic groups in all the complexes, except in the case of the acyclic mononuclear Ru(III) and VO(IV) complexes, where the Schiff base behaves as neutral tetradentate chelate with N(2)S(2) donor atoms. The ligands and the metal complexes were characterized by elemental analysis, IR, UV-vis (1)H-NMR, thermal gravimetric analysis (TGA) and ESR, as well as the measurements of conductivity and magnetic moments at room temperature. Electronic spectra and magnetic moments of the complexes indicate the geometries of the metal centers are either tetrahedral, square planar or octahedral. Kinetic and thermodynamic parameters were calculated using Coats-Redfern equation, for the different thermal decomposition steps of the complexes. The ligands and the metal complexes were screened for their antimicrobial activity against Staphylococcus aureus as Gram-positive bacteria, and Pseudomonas fluorescens as Gram-negative bacteria in addition to Fusarium oxysporum fungus. Most of the complexes exhibit mild antibacterial and antifungal activities against these organisms. PMID:22580137

Abou-Hussein, Azza A A; Linert, Wolfgang

2012-04-22

331

Properties of Asp212----Asn bacteriorhodopsin suggest that Asp212 and Asp85 both participate in a counterion and proton acceptor complex near the Schiff base  

SciTech Connect

The gene coding for bacteriorhodopsin was modified in vitro to replace Asp212 with asparagine and expressed in Halobacterium halobium. x-ray diffraction measurements showed that the major lattice dimension of purple membrane containing the mutated bacteriorhodopsin was the same as wild type. At pH greater than 7, the Asp212----Asn chromophore was blue (absorption maximum at 585 nm) and exhibited a photocycle containing only the intermediates K and L, i.e. a reaction sequence very similar to that of wild-type bacteriorhodopsin at pH less than 3 and the blue form of the Asp85----Glu protein at pH less than 9. Since in the latter cases these effects are attributed to protonation of residue 85, it now appears that removal of the carboxylate of Asp212 has similar consequences as removing the carboxylate of Asp85. However, an important difference is that only Asp85 affects the pKa of the Schiff base. At pH less than 7, the Asp212----Asn protein was purple (absorption maximum at 569 nm) but photoexcitation produced only 15% of the normal amount of M and the transport activity was partial. The reactions of the blue and purple forms after photoexcitation are both quantitatively accounted for by a proposed scheme, K in equilibrium with L1 in equilibrium with L2----BR, but with the addition of an L1 in equilibrium with M reaction with unfavorable pKa for Schiff base deprotonation in the purple form. The latter hinders the transient accumulation of M, and the consequent branching at L1 allows only partial proton transport activity. The results are consistent with the existence of a complex counterion for the Schiff base proposed earlier and suggest that Asp85, Asp212, and at least one other protonable residue participate in it.

Needleman, R.; Chang, M.; Ni, B.; Varo, G.; Fornes, J.; White, S.H.; Lanyi, J.K. (Department of Biochemistry, Wayne State University School of Medicine, Detroit, MI (USA))

1991-06-25

332

Synthesis, characterization and catalytic oxidation of para-xylene by a manganese(III) Schiff base complex on functionalized multi-wall carbon nanotubes (MWNTs).  

PubMed

In the present study, hydroxyl functionalized manganese(III) Schiff-base; [Mn((OH)(2)-salophen)Cl] [(OH)(2)-salophen] = (N,N'-bis(4-hydroxysalicylidene)phenylene-1,2-diamine); has been covalently anchored on modified multi-wall carbon nanotubes (MWNTs); [Mn((OH)(2)-salophen)Cl]@MWNTs]. The new modified MWNTs have been characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron (XPS), thermal analysis, FT-IR spectroscopy and elemental analysis. The results suggest that the symmetrical Schiff-base is a bivalent anion with tetradentate N(2)O(2) donors derived from the phenolic oxygen and azomethine nitrogen. 4-Hydroxy salophen; [(OH)(2)-salophen], complex of manganese, grafted on the walls of MWNTs have been investigated as catalysts for the aerobic oxidation of para-xylene in the absence of added halogen promoters and using tert-butylhydroperoxide (TBHP) as the initiator at low temperatures. The major products include toluic acid, toluyl aldehyde and toluyl alcohol. The MWNTs-grafted complex did not undergo any colour change during the reaction and could be easily separated and reused many times. In contrast, the neat complex, while they were active in the first cycle, was completely destroyed during the run and changed colour. They, however, gave lower conversions compared to the grafted catalyst. PMID:20601980

Salavati-Niasari, Masoud; Davar, Fatemeh; Bazarganipour, Mehdi

2010-07-02

333

Synthesis, spectroscopy and biological investigations of manganese(III) Schiff base complexes derived from heterocyclic ?-diketone with various primary amine and 2,2'-bipyridyl  

NASA Astrophysics Data System (ADS)

The mixed ligand mononuclear complex [Mn(bipy)(HPMFP)(OAc)]ClO 4 was synthesized by reaction of Mn(OAc) 3·2H 2O with HPMFP and 2,2'-bipyridyl. The corresponding Schiff base complexes were prepared by condensation of [Mn(bipy)(HPMFP)(OAc)]ClO 4 with ethylenediamine, ethanolamine and glycine (where HPMFP = 1-phenyl-3methyl-4-formyl-2-pyrazolin-5one, bipy = 2,2'-bipyridyl). All the compounds have been characterized by elemental analysis, magnetic susceptibility, conductometry measurements and 1H and 13C NMR, FT-IR, mass spectrometry. Electronic spectral and magnetic susceptibility measurements indicate square pyramidal geometry around manganese(III) ion. The thermal stabilities, activation energy E*, entropy change ? S*, enthalpy change ? H* and heat capacity of thermal degradation for these complexes were determined by TGA and DSC. The in vitro antibacterial and antifungal activity of four coordination compounds and ligand HPMFP were investigated. In vitro activates of Bacillus subtillis (MTCC-619), Staphylococcus aureus (MTCC-96), Escherichia coli (MTCC-722) and Klebsiella pneumonia (MTCC-109) bacteria and the fungus Candida albicans (ATCC-90028) were determined. All the compounds showed good antimicrobial activity. The antimicrobial activities increased as formation of Schiff base.

Surati, Kiran R.

2011-06-01

334

Syntheses, structures and properties of copper(II) complexes containing N-(2-hydroxybenzyl)-amino amide ligands  

Microsoft Academic Search

Four copper(II) complexes containing the reduced Schiff base ligands, namely, N-(2-hydroxybenzyl)-glycinamide (Hsglym) and N-(2-hydroxybenzyl)-l-alaninamide (Hsalam) have been synthesized and characterized. The crystal structures of [Cu2(sglym)2Cl2] (1), [Cu2(salam)2(NO3)2]·H2O (3), [Cu2(salam)2(NO3)(H2O)](NO3)·1.5H2O (4), [Cu2(salam)2](ClO4)2·2H2O (5) show that the Cu(II) atoms are bridged by two phenolato oxygen atoms in the dimers. The sglym ligand bonded to Cu(II) in facial manner while salam ligand prefers

Xiaobai Wang; Jun Ding; Jagadese J. Vittal

2006-01-01

335

Synthesis, characterization and biological studies of Co(II), Ni(II), Cu(II) and Zn(II) complexes with bidentate Schiff bases derived by heterocyclic ketone.  

PubMed

A series of metal complexes of Co(II), Ni(II), Cu(II) and Zn(II) have been synthesized with newly prepared biologically active ligands. These ligands were prepared by the condensation of 4-amino-5-mercapto-3-methyl-s-triazole (AMMT), 4-Amino-3-ethyl-5-mercapto-s-triazole (AEMT) with 2-acetylpyridine. The structure of the complexes have been proposed by elemental analyses, spectroscopic data i.e. IR, 1H NMR, electronic and magnetic measurements. Thermal studies of the complexes are also reported. Antibacterial activities of 10 complexes have been studied in vitro. Heterocyclic bidentate Schiff bases were associated with substantially higher antibacterial activities than some commercial antibiotics. PMID:16271421

Singh, Kiran; Barwa, Manjeet Singh; Tyagi, Parikshit

2005-11-03

336

Synthesis, spectral, thermal and thermodynamic studies of oxovanadium(IV) complexes of Schiff bases derived from 3,4-diaminobenzoic acid with salicylaldehyde derivatives.  

PubMed

Synthesis and evaluation of three new oxovanadium(IV) complexes, formed by the interaction of vanadyl acetylacetonate and the Schiff bases: 3,4-bis((E)-2-hydroxybenzylideneamino)benzoic acid (L(1)), 3,4-bis-((E)-2-hydroxy-3-methoxybenzylideneamino)benzoic acid (L(2)) and 3,4-bis((E)-2,4-dihydroxybenzylideneamino)benzoic acid (L(3)) in methanol. The complexes have been characterized and studied by IR spectra, UV-Vis spectroscopy and thermogravimetry in order to evaluate their thermal stability and thermal decomposition. According to the results discussed from TG curves, the order of thermal stability for the complexes is VOL(3)>VOL(1)>VOL(2). Their formation constants (Kf) were obtained by UV-Vis spectroscopic titration at 15, 25, 35 and 45 °C in methanol by SQUAD software. The trend of formation constants of the complexes as follows: VOL(3)>VOL(2)>VOL(1). PMID:23416918

Mohammadi, Khosro; Niad, Mahmood; Irandoost, Amene

2013-01-23

337

Synthesis, spectral, thermal and thermodynamic studies of oxovanadium(IV) complexes of Schiff bases derived from 3,4-diaminobenzoic acid with salicylaldehyde derivatives  

NASA Astrophysics Data System (ADS)

Synthesis and evaluation of three new oxovanadium(IV) complexes, formed by the interaction of vanadyl acetylacetonate and the Schiff bases: 3,4-bis((E)-2-hydroxybenzylideneamino)benzoic acid (L1), 3,4-bis-((E)-2-hydroxy-3-methoxybenzylideneamino)benzoic acid (L2) and 3,4-bis((E)-2,4-dihydroxybenzylideneamino)benzoic acid (L3) in methanol. The complexes have been characterized and studied by IR spectra, UV-Vis spectroscopy and thermogravimetry in order to evaluate their thermal stability and thermal decomposition. According to the results discussed from TG curves, the order of thermal stability for the complexes is VOL3 > VOL1 > VOL2. Their formation constants (Kf) were obtained by UV-Vis spectroscopic titration at 15, 25, 35 and 45 °C in methanol by SQUAD software. The trend of formation constants of the complexes as follows: VOL3 > VOL2 > VOL1.

Mohammadi, Khosro; Niad, Mahmood; Irandoost, Amene

2013-04-01

338

Synthesis and characterization of some monofunctional bidentate Schiff bases derived from cinnamaldehyde and s -triazoles, and their Co(II), Ni(II), Cu(II) and Zn(II) complexes  

Microsoft Academic Search

A new series of complexes of Co(II), Ni(II), Cu(II) and Zn (II) with Schiff bases derived from the condensation of cinnamaldehyde\\u000a with 4-amino-5-mercapto-s-triazole and 4-amino-5-mercapto-3-methyl-s-triazole have been synthesized. The complexes are characterized by elemental analyses,1H NMR, IR, electronic spectra and magnetic susceptibility measurements. The spectroscopic studies reveal that Schiff base\\u000a acts as bidentate ligand with N, S donor set. Thermal

Ashok K Sen; Gurmit Singh; Kiran Singh; Ram N Handa; Surendra N Dubey; Philip J Squattrito

1998-01-01

339

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

340

Steric, geometrical and solvent effects on redox potentials in salen-type copper(II) complexes.  

PubMed

Two diastereomers of the Schiff base ligand [N,N'-bis(2'-hydroxyphenyl)phenylmethylidene]-1,2-diamino-1,2-diphenylethane (H(2)L) were used for the analyses of the redox behaviour of the copper(ii) complexes [Cu(L(R,R/S,S))] (rac-) and [Cu(L(R,S))] (meso-). Both complexes were structurally characterised by X-ray crystallographic studies and showed square planar geometries. The reduction potential of Cu(II) to Cu(I) for meso- was higher than that for rac-. This is due to the steric effect of the phenyl substituents and the geometrical change in the copper(i) state, which is supported by DFT calculations. A red shift of the absorption spectrum was observed for meso- in the visible region by the change of solvent from dichloromethane to pyridine, while rac- did not show a significant change. The effect of solvent on the reduction potential was found to be relatively small. The geometrical effect is more important for understanding the electrochemical behaviour in this system. PMID:19759940

Hirotsu, Masakazu; Kuwamura, Naoto; Kinoshita, Isamu; Kojima, Masaaki; Yoshikawa, Yuzo; Ueno, Keiji

2009-07-27

341

Mononuclear Ru(II) Carbonyl Complexes Containing Quadridentate Schiff Bases as N2O2 Donors: Synthesis, Spectral, Catalytic Properties, and Antibacterial Activity  

Microsoft Academic Search

Reactions of Ru3(CO)12with novel tetradentate Schiff bases ligands H2L in benzene under reduced pressure afforded the formation of new Ru(II) complexes of the type [Ru(CO)2(L)] where L = anion of N,Nbis(salicylaldehyde)4,5-dimethyl-1, 2-phenylenediamine (saldmophn), N,Nbis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (saldcophn), N,Nbis(salicylalde-hyde)2,3-diaminonaphthalene (saldnap), N,Nbis(o-vanillin)4, 5-dimethy-l,2-phenylenediamine (ovaldmophn), and N,Nbis(o-vanillin)4,5-dichloro-1,2-phenylenediamine (ovaldcophn), respectively. All the newly synthesized complexes were investigated using elemental analysis, FT-IR, UV-Vis, mass spectrometry, and magnetic

Ayman A. Abdel Aziz

2011-01-01

342

Syntheses, characterization and crystal structures of two square-planar Ni(II) complexes with unsymmetrical tridentate Schiff base ligands and monodentate pseudohalides  

Microsoft Academic Search

Two new square-planar Ni(II) complexes, [NiL1(NCS)] (1) and [NiL2(N3)] (2) have been synthesized with the unsymmetrical tridentate Schiff base ligands [(CH3)2NCH2CH2N=C(CH3)CH=C(OH)(C6H5)], L\\u000a \\u000a 1\\u000a \\u000a H, derived from benzoylacetone and 2-dimethylaminoethylamine and [(CH3CH2)2NCH2CH2N=C(CH3)CH=C(OH)(C6H5)], L\\u000a \\u000a 2\\u000a \\u000a H, derived from benzoylacetone and 2-diethylaminoethylamine, respectively. The complexes have been characterized by elemental\\u000a analysis, FT-IR, UV-Vis spectroscopy, electrochemical and thermal methods (where applicable). Structures have been

Shyamapada Shit; Soma Sen; Samiran Mitra; David L. Hughes

2009-01-01

343

Syntheses of new TTF-based metal complexes for conducting and magnetic systems: Schiff base-type metal complex with partially oxidized TTF moiety  

NASA Astrophysics Data System (ADS)

New TTF-based ligands (TTF=tetrathiafulvalene) with Schiff base-type coordination sites have been synthesized: 4,5-bis(4-salicylideneiminophenyl)-4?,5?-ethylenedithio-TTF (1a), 4,5-bis(4-picolinideneiminophenyl)-4?,5?-ethylenedithio-TTF (1b), and 4-(2-salicylideneiminoethylthio)-5-methyl-4?,5?-ethylenedithio-TTF (Hsae-TTF). X-ray crystallography for 1a revealed that 1a has rigid structure around the coordination sites, which prevents it to form metal complexes. On the other hand, Hsae-TTF ligand has flexibility around its coordination sites due to alkyl chain spacer, and gave mononuclear complexes with Ni(II) and Cu(II) ions, [MII(saeTTF)2] (MII=Ni(II) and Cu(II)). The metal ions in [MII(saeTTF)2] have a square planar coordination structure with two TTF-based ligands, which was sandwiched by two neutral TTF moieties. The Cu(II) complex, [CuII(saeTTF)2], yielded charge transfer (CT) complexes with acceptors such as F4TCNQ, DDQ, and iodine. CT complexes with F4TCNQ and iodine were semiconductive, but that with DDQ was insulator. This is due to the difference of the degree of charge transfer; TTF moiety in F4TCNQ salt was partially oxidized but that of DDQ salt was completely oxidized. The radical cation salts of [CuII(saeTTF)2] with PF6- anion was also obtained in 1:1 donor and anion ratio by electrocrystallization. The donor and anion ratio indicates that the oxidation state of TTF moieties in the radical salt, [CuII(saeTTF)2]PF6, was partial oxidation state.

Nishikawa, H.; Oshima, H.; Narita, K.; Oshio, H.

2010-06-01

344

Synthesis and Characterization of Some Mononuclear Complexes of the Schiff Base {N,N??2,2??Bis(Aminoethyl)Methylaminebis?(3?Carboxysalicylaldimine)}  

Microsoft Academic Search

Reaction of 3?formylsalicylic acid with diethylenetriamine yielded the Schiff base {N,N?–2,2??bis(aminoethyl)methylaminebis(3?carboxysalicylaldimine)}, abbreviated as H4fsadien. The interaction of H4fsadien with CoCl2 · 6H2O, Ni(OAc)2 · 4H2O, Cu(OAc)2 · H2O, Zn(OAc)2 · 2H2O, Na2MoO4 · 2H2O, WO2(acac)2, (NH4)2[MoOCl5], (pyH)2[Mo(SCN)6], FeSO4 · 7H2O and FeCl3 · 6H2O under varied reaction conditions have been studied. The reactions of some of the new metal complexes isolated in this study have also been investigated with a view to develop new

Kamalendu Dey; Ranabir Bhowmick; Susobhan Biswas; Dhananjoy Koner; Saikat Sarkar

2005-01-01

345

Synthesis, characterization and structure of nickel(II) complexes of a 16-membered mixed-donor macrocyclic Schiff base ligand, potentially hexadentate, bearing two pendant alcohol functions  

Microsoft Academic Search

The reactions of NiX2·6H2O (X=Cl?, ClO4-, NO3-) with a new macrocyclic Schiff base ligand (L=8,9,18,19-tetrahydro-7H,17H-dibenzo[f,o][1,5,9,13]dioxadiaza cyclohexadecine-8,18-diol), potentially hexadentate containing two alcoholic pendant arms, have been investigated by template condensation of 2-[3-(2-formylphenoxy)-2-hydroxypropoxy]benzaldehyde and 1,3-diamino-2-propanol. The isolation of a selection of 1:1 (metal:ligand) complexes of nickel(II) has been carried out and IR and UV–Vis spectroscopy, conductance measurements and X-ray determination have been

Ali Akbar Khandar; Seyed Abolfazl Hosseini-Yazdi; Masomeh Khatamian; Patrick McArdle; Seyed Amir Zarei

2007-01-01

346

Synthesis, characterization, and thermodynamic studies of the interaction of some new water-soluble Schiff-base complexes with bovine serum albumin  

Microsoft Academic Search

Some new water-soluble Schiff-base complexes Na2[M(5-SO3-2,3-salpyr)(H2O)n]?·?2H2O (5-SO3-2,3-salpyr?=?N,N?-bis(5-sulphosalicyliden)-2,3-diaminopyridine and M?=?Zn, Cu, Ni) were synthesized and characterized by elemental analysis, IR, H NMR, magnetic susceptibility measurement, thermal analysis, and UV-Vis spectroscopy. The mechanism of binding of Na2[M(5-SO3-2,3-salpyr)(H2O)n]?·?2H2O with bovine serum albumin (BSA) was investigated by fluorescence spectroscopy. The fluorescence titration revealed that the intrinsic fluorescence of BSA was quenched by Na2[M(5-SO3-2,3-salpyr)], which

Mozaffar Asadi; Somaye Barzegar Sadi; Zahra Asadi; Reza Yousefi; Ahmad Reza Barzegar Sadi; Hojjat Khalili-Hezarjaribi

2012-01-01

347

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

348

Synthesis, spectral and antimicrobial activity of Zn(II) complexes with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and benzaldehyde/2-hydroxyacetophenone/indoline-2,3-dione  

NASA Astrophysics Data System (ADS)

Zn(II) complexes have been synthesized by reacting zinc acetate with Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and 2-hydroxyacetophenone/benzaldehyde/indoline-2,3-dione. All these complexes are soluble in DMF and DMSO; low molar conductance values indicate that they are non electrolytes. Elemental analyses suggest that the complexes have 1:2 metal to ligands stoichiometry of the types [ZnL2(H2O)2](L = monoanionic Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and 2-hydroxyacetophenone/indoline-2,3-dione) [ZnL2'(OOCCH3)2(H2O)2](L' = neutral Schiff bases derived from 2-hydrazino-5-[substituted phenyl]-1,3,4-thiadiazole and benzaldehyde), and they were characterized by IR, 1H NMR, and 13C NMR. Particle sizes of synthesized compounds were measured with dynamic light scattering (DLS) analyser which indicates that particle diameter are of the range ca. 100-200 nm. All these Schiff bases and their complexes have also been screened for their antibacterial (Bacillus subtilis (B. subtilis), Escherichia coli (E. coli) and antifungal activities (Colletotrichum falcatum (C. falcatum), Aspergillus niger (A. niger), Fusarium oxysporium (F. oxysporium) Curvularia pallescence (C. pallescence). The antimicrobial activities have shown that upon complexation the activity increases.

Singh, Ajay K.; Pandey, O. P.; Sengupta, S. K.

2013-09-01

349

Synthesis, spectroscopic studies and structures of square-planar nickel(II) and copper(II) complexes derived from 2-{(Z)-[furan-2-ylmethyl]imino]methyl}-6-methoxyphenol  

Microsoft Academic Search

Two new nickel(II) [Ni(L)2] and copper(II) [Cu(L)2] complexes have been synthesized with bidentate NO donor Schiff base ligand (2-{(Z)-[furan-2-ylmethyl]imino]methyl}-6-methoxyphenol) (HL) and both complexes Ni(L)2 and Cu(L)2 have been characterized by elemental analyses, IR, UV–vis, 1H, 13C NMR, mass spectroscopy and room temperature magnetic susceptibility measurement. The tautomeric equilibria (phenol-imine, O–H?N and keto-amine, O?H–N forms) have been systemetically studied by using

Hüseyin Ünver; Zeliha Hayvali

2010-01-01

350

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

351

Synthesis, spectral, photolysis and electrochemical studies of mononuclear copper(II) complex with a new asymmetric tetradentate ligand: application as copper nanoparticle precursor.  

PubMed

A copper(II) complex with asymmetric tetradentate Schiff base ligand, obtained by the single condensation of 1,2-diaminopropane with 2-hydroxy-5-methoxy benzaldehyde was prepared. The ligand and complex were characterized by their IR, UV-Vis, FT-IR, NMR spectra and CV. Crystal structures of the mononuclear copper complex have been obtained by X-ray diffraction studies which revealed to be distorted square planner coordination geometry. The spectral data confirm coordination of ligand to copper ion center. The redox properties of complex at different scan rates exhibit grossly similar features consisting of an electrochemically pseudo-reversible Cu(II)/Cu(I) reduction at ca. -0.97 V and pseudo-reversible Cu(I)/Cu(II) oxidation at ca. -0.81 V. The copper nanoparticles with average size of 73 nm were formed by thermal reduction of copper complex in the presence of triphenylphosphine. PMID:22728968

Habibi, Mohammad Hossein; Mikhak, Maryam

2012-06-06

352

Synthesis, spectroscopic, photoluminescence properties and biological evaluation of novel Zn(II) and Al(III) complexes of NOON tetradentate Schiff bases  

NASA Astrophysics Data System (ADS)

Novel mononuclear Zn(II) and Al(III) complexes were synthesized from the reactions of Zn(OAc)2·2H2O and anhydrous AlCl3 with neutral N2O2 donor tetradentate Schiff bases; N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H2L1) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2L2). The new complexes were fully characterized by using micro analyses (CHN), FT-IR, 1H NMR, UV-Vis spectra and thermal analysis. The analytical data have been showed that, the stoichiometry of the complexes is 1:1. Spectroscopic data suggested tetrahedral and square pyramidal geometries for Zn(II) and Al(III) complexes, respectively. The synthesized Zn(II), and Al(III) complexes exhibited intense fluorescence emission in the visible region upon UV-excitation in methylene chloride solution at ambient temperature. This high fluorescence emission was assigned to the strong coordination of the ligands to the small and the highly charged Zn(II) and Al(III) ions. Such strong coordination seems to extend the ?-conjugation of the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. As a potential application the biological activity (e.g., antimicrobial action) of the prepared ligands and complexes was assessed by in-vitro testing of their effect on the growth of various strains of bacteria and fungi.

Abdel Aziz, Ayman A.; Badr, Ibrahim H. A.; El-Sayed, Ibrahim S. A.

2012-11-01

353

Synthesis, spectroscopic, photoluminescence properties and biological evaluation of novel Zn(II) and Al(III) complexes of NOON tetradentate Schiff bases.  

PubMed

Novel mononuclear Zn(II) and Al(III) complexes were synthesized from the reactions of Zn(OAc)(2).2H(2)O and anhydrous AlCl(3) with neutral N2O2 donor tetradentate Schiff bases; N,N'bis(salicylaldehyde)4,5-dimethyl-1,2-phenylenediamine (H(2)L(1)) and N,N'bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H(2)L(2)). The new complexes were fully characterized by using micro analyses (CHN), FT-IR, (1)H NMR, UV-Vis spectra and thermal analysis. The analytical data have been showed that, the stoichiometry of the complexes is 1:1. Spectroscopic data suggested tetrahedral and square pyramidal geometries for Zn(II) and Al(III) complexes, respectively. The synthesized Zn(II), and Al(III) complexes exhibited intense fluorescence emission in the visible region upon UV-excitation in methylene chloride solution at ambient temperature. This high fluorescence emission was assigned to the strong coordination of the ligands to the small and the highly charged Zn(II) and Al(III) ions. Such strong coordination seems to extend the ?-conjugation of the complexes. Thermal analysis measurements indicated that the complexes have good thermal stability. As a potential application the biological activity (e.g., antimicrobial action) of the prepared ligands and complexes was assessed by in-vitro testing of their effect on the growth of various strains of bacteria and fungi. PMID:22813990

Abdel Aziz, Ayman A; Badr, Ibrahim H A; El-Sayed, Ibrahim S A

2012-06-28

354

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

355

Synthesis, characterization and electrochemical behavior of some Ni(II), Cu(II), Co(II) and Cd(II) complexes of ONS type tridentate Schiff base ligand.  

PubMed

Tridentate Schiff base (H(2)L) ligand was synthesized via condensation of o-hydroxybenzaldehyde and 2-aminothiophenol. The metal complexes were prepared from reaction of the ligand with corresponding metal salts presence of substituted pyridine in two different solvents (MeOH or MeCN). The ligand and metal complexes were then characterized by using FTIR, TGA, (1)H NMR and (13)C NMR spectroscopies. The FTIR spectra showed that H(2)L was coordinated to the metal ions in tridentate manner with ONS donor sites of the azomethine N, deprotonated phenolic-OH and phenolic-SH. Furthermore, substituted pyridine was coordinated to the central metal atoms. The thermal behavior of the complexes was investigated by using TGA method and dissociations indicated that substituted pyridine and ligand were leaved from coordination. This coordination of the metal complexes was correlated by (1)H NMR and (13)C NMR. Finally, electrochemical behavior of the ligand and a Ni(II) complex were investigated. PMID:21982158

Durmus, Sefa; Atahan, Alparslan; Zengin, Mustafa

2011-07-29

356

Reactivity of tris(acetylacetonato) iron(III) with tridentate [ONO] donor Schiff base as an access to newer mixed-ligand iron(III) complexes.  

PubMed

Two new mixed-ligand iron(III) complexes, [Fe(L(n))(acac)(C(2)H(5)OH)] incorporating coordinated ethanol from the reaction solvent were accessed from the reaction of [Fe(acac)(3)] with [ONO] donor dibasic tridentate unsymmetrical Schiff base ligands derived from condensation of 2-hydroxy-1-napthaldehyde with 2-aminophenol (H(2)L(1)) or 2-aminobenzoic acid (H(2)L(2)). The thermal study (TGA-DTA) provided evidence for weakly bound ethanol which is readily substituted by neutral N-donor molecule imidazole, benzimidazole or pyridine to produce an array of newer complexes, [Fe(L(n))(acac)X] (n=1, 2; X=Im, Bim, Py). The compounds were characterized by elemental analyses, FT-IR, UV-vis, solution electrical conductivity, FAB mass, (1)H and (13)C NMR spectroscopy. Room temperature magnetic susceptibility measurements (?(eff)?5.8 B.M.) are consistent with spin-free octahedral iron(III) complexes. Cyclic voltammetry of ethanol complexes revealed a quasi-reversible one electron redox response (?E(p)>100 mV) for the Fe(III)/Fe(II) couple. Low half wave redox potential (E(1/2)) values suggested easy redox susceptibility. The ground state geometries of the ethanol and imidazole complexes have been ascertained to be distorted octahedral by density functional theory using DMol3 program at BLYP/DNP level. PMID:21345718

Bhattacharjee, Chira R; Goswami, Pankaj; Pramanik, Harun A R; Paul, Pradip C; Mondal, Paritosh

2011-01-26

357

Synthesis, crystal structures, and luminescent properties of phenoxo-bridged heterometallic trinuclear propeller- and sandwich-like Schiff-base complexes.  

PubMed

A series of phenoxo-bridged heterometallic Schiff-base trinuclear complexes Zn-M-Zn [M = Cd(II), Pb(II), Nd(III), Eu(III), Gd(III), Tb(III), and Dy(III)] have been synthesized by a rational structural design based on two symmetrical Schiff-base ligands N,N'-bis(3-methoxysalicylidene)propylene-1,3-diamine (H(2)L(a)) and N,N'-bis(3-methoxysalicylidene)benzene-1,2-diamine (H(2)L(b)). Single X-ray diffraction analysis reveals a similar molecular structure among the eight propeller-like and seven sandwich-type phenoxo-bridged Zn-M-Zn complexes. In the compounds Cd[Zn(L(a))Cl](2) (1), {Cd[Zn(L(b))Cl](2)}.H(2)O (2), {Pb[Zn(L(b))Cl](2)}.2H(2)O (4), {Nd[Zn(L(a))Cl](2)(H(2)O)}.0.5ZnCl(4) .2H(2)O (5), and{M(III)[Zn(L(a))Cl](2)(H(2)O)}.0.5ZnCl(4).2MeOH [M = Eu(7), Gd (9), Tb (11), and Dy (13)], two [Zn(L)Cl](-) units coordinate to the central metal ion as a tetradentate ligand using its four oxygen atoms, forming a two-blade propeller-like left-handed and right-handed chiral Zn-M-Zn configuration despite the racemic nature of the whole complexes. Compounds {Pb[Zn(L(a))Cl](2)}.MeOH (3), {Nd[Zn(L(b))Cl](2)(DMF)(OAc)}.CH(3)CN (6), {Eu[Zn(L(b))Cl](2)(DMF)(OAc)}.CH(3)CN (8), {Gd[Zn(L(b))Cl](2)(DMF)(2)}.Cl.2H(2)O (10), {Tb[Zn(L(b))Cl](2)(DMF)(2)}.Cl.2H(2)O (12), {Dy[Zn(L(b))Cl](2)(DMF)(2)}.Cl.2H(2)O (14), and {Pb[Zn(L(b))Cl](2)}.2H(2)O (15) exhibit a relatively rare sandwich-type structure with a central metal ion clamped by two [Zn(L)Cl](-) units. Photophysical studies indicate that all of the complexes exhibit luminescence both in solution and in solid sate, and there exists an energy transfer from the [Zn(L)Cl](-) unit to the central rare earth ions of Nd(III) (5 and 6), Tb(III) (11), and Dy(III) (for 13). In particular, systematic and comparative investigation of the photophysical properties of these trinuclear complexes reveals that the luminescence properties could easily be tuned by changing the central metal or the Schiff-base ligand. PMID:19496590

Wang, Hailong; Zhang, Daopeng; Ni, Zhong-Hai; Li, Xiyou; Tian, Laijin; Jiang, Jianzhuang

2009-07-01

358

Solution and solid-state characterization of europium and gadolinium Schiff base complexes and assessment of their potential as contrast agents in magnetic resonance imaging  

SciTech Connect

Two lanthanide Schiff base macrocyclic complexes, LnAM(OAc){sub 2}Cl{center dot}4H{sub 2}O (Ln = Eu, Gd; HAM - HexaAzaMacrocycle = C{sub 22}H{sub 26}N{sub 6}), have been characterized in view of the potential of the Gd complex as a magnetic resonance imaging (MRI) contrast agent. The relaxivity of GdHAM(OAc){sub 2}Cl was measured at 300 and 20 MHz and is as high as that for the gadolinium aquo ion. The number of coordinated waters, q, was measured by comparison of the luminescent lifetimes of EuHAM(OAc){sub 2}Cl in H{sub 2}O and D{sub 2}O and found to be between three and four. The complex GdHAM(OAc){sub 2}Cl{center dot}4H{sub 2}O was characterized by single-crystal X-ray diffraction. The complex crystallizes in space group P{bar 1} with Z = 2, a = 10.032 (2) {angstrom}, b = 12.765 (2) {angstrom}, c = 13.668 (3) {angstrom}, {alpha} = 69.190{degree} (9){degree}, {beta} = 72.405{degree} (9){degree}, and {gamma} = 74.07{degree} (1){degree}.

Smith, P.H.; Brainard, J.R.; Morris, D.E.; Jarvinen, G.D.; Ryan, R.R. (Los Alamos National Lab., NM (USA))

1989-09-13

359

Synthesis, Spectroscopic Studies, and In Vitro Antifungal Activity of Organosilicon(IV) and Organotin(IV) Complexes of 4Amino5-mercapto-3-methyl-S-triazole Schiff Bases  

Microsoft Academic Search

The Schiff bases derived from condensation of s-triazole with heterocyclic aldehydes and their 1:1 and 1:2 complexes have been synthesized. These complexes have been characterized by elemental analyses, molar conductance and spectroscopic studies, including UV, IR, H, C, Si, and Sn NMR spectroscopy. On the basis of these studies, the resulting complexes have been proposed to have trigonal bipyramidal and

Kiran Singh; Dharampal; Vipin Parkash

2008-01-01

360

Synthesis and characterization of Co(II), Ni(II), Cu(II) and Zn(II) complexes of tridentate Schiff base derived from vanillin and DL-alpha-aminobutyric acid.  

PubMed

Co(II), Ni(II), Cu(II) and Zn(II) complexes of the Schiff base derived from vanillin and dl-alpha-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 all the complexes are non-electrolytes. IR results demonstrate the tridentate binding of the Schiff base ligand involving azomethine nitrogen, phenolic oxygen and carboxylato oxygen atoms. The IR data also indicate the coordination of a water molecule with the metal ion in the complex. The electronic spectral measurements show that Co(II) and Ni(II) complexes have tetrahedral geometry, while Cu(II) complex has square planar geometry. The powder XRD studies indicate that Co(II) and Cu(II) complexes are amorphous, whereas Ni(II) and Zn(II) complexes are crystalline in nature. Magnetic measurements show that Co(II), Ni(II) and Cu(II) complexes have paramagnetic behaviour. Antibacterial results indicated that the metal complexes are more active than the ligand. PMID:17964848

Nair, M Sivasankaran; Joseyphus, R Selwin

2007-09-21

361

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  

NASA Astrophysics Data System (ADS)

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(H 2O)], where L is the Schiff base ligand. The conductance data indicate that all the complexes are non-electrolytes. IR results demonstrate the tridentate binding of the Schiff base ligand involving azomethine nitrogen, phenolic oxygen and carboxylato oxygen atoms. The IR data also indicate the coordination of a water molecule with the metal ion in the complex. The electronic spectral measurements show that Co(II) and Ni(II) complexes have tetrahedral geometry, while Cu(II) complex has square planar geometry. The powder XRD studies indicate that Co(II) and Cu(II) complexes are amorphous, whereas Ni(II) and Zn(II) complexes are crystalline in nature. Magnetic measurements show that Co(II), Ni(II) and Cu(II) complexes have paramagnetic behaviour. Antibacterial results indicated that the metal complexes are more active than the ligand.

Nair, M. Sivasankaran; Joseyphus, R. Selwin

2008-09-01

362

Theoretical and electrochemical studies on organometallic symmetrical schiff base complexes of Zn(II), Cu(II), Ni(II) and Co(II).  

PubMed

The electronic communication between two redox centres through a Schiff base complex has been investigated in a series of ethylenediimine-bis(1-ferrocenyl-1,3-butanedionate) complexes of Zn(II) 1, Cu(II) 2, Ni(II) 3 and Co(II) 4. Cyclic voltammetry experiments of 1 and 2 exhibit a unique two-electron reversible oxidation wave, whereas in the case of 3 and 4 two and three one-electron oxidation processes are, respectively, observed. These results suggest some electronic interaction between the iron atoms of the ferrocenyl groups. DFT calculations carried out on model complexes show that for all the studied compounds the removal of the first two electrons corresponds to the oxidation processes of the iron centres in the weakly coupled ferrocenyl termini. The electronic communication between the two iron centres increases on going from 1 to 4. Finally, a re-indexation of the bands observed in the UV-Visible spectra has been carried out using TDDFT calculations. PMID:18399232

Fuentealba, Mauricio; Garland, María Teresa; Carrillo, David; Manzur, Carolina; Hamon, Jean-René; Saillard, Jean-Yves

2008-01-01

363

Cu(II), Co(II) and Ni(II) complexes of new Schiff base ligand: Synthesis, thermal and spectroscopic characterizations  

NASA Astrophysics Data System (ADS)

Cu(II), Co(II), and Ni(II) complexes were synthesized from 2-[(5-o-chlorophenylazo-2-hydroxybenzylidin)amino]-phenol Schiff base (H2L). Metal ions coordinate in a tetradentate or hexadentate features with these O2N donor ligand, which are characterized by elemental analyses, magnetic moments, infrared, Raman laser, electronic, and 1H NMR spectral studies. The elemental analysis suggests the stoichiometry to be 1:1 (metal:ligand). Reactions with Cu(II), Co(II) and Ni(II), resulted [Cu(H2L)(H2O)2(Cl)]Cl, [Co(H2L)(H2O)3]Cl2?3H2O and [Ni(H2L)(H2O)2]Cl2?6H2O. The thermal decomposition behavior of H2L complexes has been investigated by thermogravimetric analysis (TG/DTG) at a heating rate of 10 °C min-1 under nitrogen atmosphere. The brightness side in this study is to take advantage for the preparation and characterizations of single phases of CuO, CoO and NiO nanoparticles using H2L complexes as precursors via a solid-state decomposition procedure. The crystalline structures of products using X-ray diffractometer (XRD), morphology of particles by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) were investigated.

Refat, Moamen S.; El-Sayed, Mohamed Y.; Adam, Abdel Majid A.

2013-04-01

364

A new tridentate Schiff base Cu(II) complex: synthesis, experimental and theoretical studies on its crystal structure, FT-IR and UV-Visible spectra.  

PubMed

A new Cu(II) complex [Cu(L)(NCS)] has been synthesized, using 1-(N-salicylideneimino)-2-(N,N-methyl)-aminoethane as tridentate ONN donor Schiff base ligand (HL). The dark green crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FT-IR) and UV-Visible spectra. Electronic structure calculations at the B3LYP and MP2 levels of theory are performed to optimize the molecular geometry and to calculate the UV-Visible and FT-IR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TD-DFT) method is used to calculate the electronic transitions of the complex. A scaling factor of 1.015 is obtained for vibrational frequencies computed at the B3LYP level using basis sets 6-311G(d,p). It is found that solvent has a profound effect on the electronic absorption spectrum. The UV-Visible spectrum of the complex recorded in DMSO and DMF solution can be correctly predicted by a model in which DMSO and DMF molecules are coordinated to the central Cu atom via their oxygen atoms. PMID:23562742

Saheb, Vahid; Sheikhshoaie, Iran; Setoodeh, Nasim; Rudbari, Hadi Amiri; Bruno, Giuseppe

2013-03-14

365

A new tridentate Schiff base Cu(II) complex: Synthesis, experimental and theoretical studies on its crystal structure, FT-IR and UV-Visible spectra  

NASA Astrophysics Data System (ADS)

A new Cu(II) complex [Cu(L)(NCS)] has been synthesized, using 1-(N-salicylideneimino)-2-(N,N-methyl)-aminoethane as tridentate ONN donor Schiff base ligand (HL). The dark green crystals of the compound are used for single-crystal X-ray analysis and measuring Fourier Transform Infrared (FT-IR) and UV-Visible spectra. Electronic structure calculations at the B3LYP and MP2 levels of theory are performed to optimize the molecular geometry and to calculate the UV-Visible and FT-IR spectra of the compound. Vibrational assignments and analysis of the fundamental modes of the compound are performed. Time-dependent density functional theory (TD-DFT) method is used to calculate the electronic transitions of the complex. A scaling factor of 1.015 is obtained for vibrational frequencies computed at the B3LYP level using basis sets 6-311G(d,p). It is found that solvent has a profound effect on the electronic absorption spectrum. The UV-Visible spectrum of the complex recorded in DMSO and DMF solution can be correctly predicted by a model in which DMSO and DMF molecules are coordinated to the central Cu atom via their oxygen atoms.

Saheb, Vahid; Sheikhshoaie, Iran; Setoodeh, Nasim; Rudbari, Hadi Amiri; Bruno, Giuseppe

2013-06-01

366

Two new end-to-end single dicyanamide bridged Cu(II) complexes with Schiff base ligands: Structural, electrochemical and magnetic properties  

Microsoft Academic Search

The synthesis, crystal structures and magnetic properties of two different copper(II) complexes of formula [Cu(L1)(dca)]n·nClO4 (1) and [Cu(L2)]2(dca)(ClO4) (2) [L1=N,N-dimethylethylene-N?-(pyridine-2-carbaldiiminato), HL2=N,N-dimethylethylene-N?-salicylaldiiminato, dca=dicyanamide anion] are described. Spectroscopic and electrochemical properties have also been discussed. A one-dimensional chain structure with single, symmetrical, ?1,5-dca bridges is found in compound 1. The copper atom in 1 has a square pyramidal geometry. A tridentate Schiff

Ruma Karmakar; Chirantan Roy Choudhury; David L. Hughes; Glenn P. A. Yap; M. Salah El Fallah; Cédric Desplanches; Jean-Pascal Sutter; Samiran Mitra

2006-01-01

367

Synthesis, spectral characterization and in vitro biological studies of Co(II), Ni(II) and Cu(II) complexes with 1,2,4-triazole Schiff bases.  

PubMed

A series of metal complexes of cobalt(II), nickel(II) and copper(II) have been synthesized with newly derived biologically active ligands. These ligands were synthesized by the condensation of 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and 8-formyl-7-hydroxy-4-methylcoumarin. The probable structure of the complexes has been proposed on the basis of elemental analyses and spectral (IR, Uv-Vis, magnetic, ESR, FAB-mass and thermal studies) data. Electro chemical study of the complexes is also reported. All these complexes are non-electrolytes in DMF and DMSO. All the ligands and their Co(II), Ni(II) and Cu(II) complexes were screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Staphylococcus pyogenes and Pseudomonas aeruginosa) and antifungal (Aspergillus niger, Aspergillus flavus and cladosporium) activities by MIC method. The brine shrimp bioassay was also carried out to study their in vitro cytotoxic properties. PMID:18686135

Bagihalli, Gangadhar B; Badami, Prema S; Patil, Sangamesh A

2009-04-01

368

Interactions of Trivalent Lanthanide Cations with a New Hexadentate Di-Schiff Base: New Lanthanide(III) Complexes from (NE,N?E)-2,2?-(ethane-1,2-diylbis(oxy))bis(N-(pyridin-2-ylmethylene)ethanamine)  

PubMed Central

The novel lanthanide(III) complexes [Ln(NO3)2L](NO3)·3MeOH (Ln = La 1, Pr 2) and [Ln(NO3)3L](NO3)·2MeOH (Ln = Gd 3, Yb 4), where L = (NE,N?E)-2,2?-(ethane-1,2-diylbis(oxy))bis(N-(pyridin-2-ylmethylene)ethanamine), have been obtained by direct reaction of the Schiff base ligand and the corresponding hydrated lanthanide(III) nitrates in methanol. All complexes were characterized spectroscopically and thermogravimetrically. Complex 4 was also characterized with crystallographic studies: orthorhombic P212121, a = 10.6683(14), b = 13.4752(15), c = 19.3320(26) Å. In the molecular structure of 4, Yb(III) is surrounded by all donor atoms of the Schiff base (four nitrogen and two oxygen atoms) and four oxygen atoms belonging to two bidentate chelating nitrato ligands.

Tsiouri, Mantha; Skorda, Konstantina; Papadimitriou, Christos; Li, Yang; Woollins, J. Derek; Plakatouras, John C.

2010-01-01

369

Syntheses and Crystal Structures of Two Isostructural Zinc(II) Complexes With Schiff-bases 2-Bromo-4-chloro-6-[(3-methylaminopropylimino)methyl]phenol and 2,4-Dichloro-6-[(3-methylaminopropylimino)methyl]phenol  

Microsoft Academic Search

Two new isostructural mononuclear zinc(II) complexes, [Zn(C11H14Cl2N2O)(NCS)(CH3COO)] and [Zn(C11H14BrClN2O) (NCS)(CH3COO)], have been synthesized from the Schiff-bases 2-bromo-4-chloro-6-[(3-methylaminopropylimino)methyl]phenol and 2,4-dichloro-6-[(3-methylaminopropylimino)methyl]phenol, respectively. Both complexes were characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. The Zn atom in each of the complexes is coordinated by one phenolic oxygen atom and one imine nitrogen atom of a Schiff-base ligand, one nitrogen atom

De-Suo Yang; Hai-Yun Zhu

2008-01-01

370

Synthesis and DNA binding studies of Ni(II), Co(II), Cu(II) and Zn(II) metal complexes of N 1,N 5-bis[pyridine-2-methylene]-thiocarbohydrazone Schiff-base ligand  

NASA Astrophysics Data System (ADS)

The thiocarbohydrazone Schiff-base ligand with a nitrogen and sulphur donor was synthesized through condensation of pyridine-2-carbaldehyde and thiocarbohydrazide. Schiff-base ligands have the ability to conjugate with metal salts. A series of metal complexes with a general formula [MCl 2(H 2L)]· nH 2O (M dbnd Ni, Co, Cu and Zn) were synthesized by forming complexes of the N 1,N 5-bis[pyridine-2-methylene]-thiocarbohydrazone (H 2L) Schiff-base ligand. These metal complexes and ligand were characterized by using ultraviolet-visible (UV-Vis), Fourier Transform Infrared (FT-IR), 1H and 13C NMR spectroscopy and mass spectroscopy, physicochemical characterization, CHNS and conductivity. The biological activity of the synthesized ligand was investigated by using Escherichia coli DNA as target. The DNA interaction of the synthesized ligand and complexes on E. coli plasmid DNA was investigated in the aqueous medium by UV-Vis spectroscopy and the binding constant ( Kb) was calculated. The DNA binding studies showed that the metal complexes had an improved interaction due to trans-geometrical isomers of the complexes than ligand isomers in cis-positions.

Tiwari, A. D.; Mishra, A. K.; Mishra, S. B.; Mamba, B. B.; Maji, B.; Bhattacharya, S.

2011-09-01

371

Synthesis, spectroscopic, antimicrobial and DNA cleavage studies of new Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes with naphthofuran-2-carbohydrazide Schiff base  

NASA Astrophysics Data System (ADS)

A series of Co(II), Ni(II), Cu(II), Cd(II), Zn(II) and Hg(II) complexes have been synthesized with newly synthesized Schiff base derived from naphthofuran-2-carbohydrazide and cinnamaldehyde. The elemental analyses of the complexes are confined to the stoichiometry of the type MLCl2 [M = Co(II) and Cu(II)], ML2Cl2 [M = Ni(II), Cd(II), Zn(II) and Hg(II)] respectively, where L is Schiff base ligand. Structures have been proposed from elemental analyses, IR, electronic, mass, 1H NMR, ESR spectral data, magnetic, and thermal studies. The measured low molar conductance values in DMF indicate that the complexes are non-electrolytes. Spectroscopic studies suggest coordination occurs through azomethine nitrogen and carbonyl oxygen of the ligand with the metal ions. The Schiff base and its complexes have been screened for their antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal (Aspergillus niger, Aspergillus flavus, Cladosporium and Candida albicans) activities by minimum inhibitory concentration (MIC) method. The DNA cleavage studies by agarose gel electrophoresis method was studied for all the complexes.

Halli, Madappa B.; Sumathi, R. B.

2012-08-01

372

Anti-inflammatory activity of some copper(II) complexes.  

PubMed

Anti-inflammatory activity of some copper(II) neutral complexes and complexated salts on different animal models of inflammation has been investigated. In a preliminary screening 5 complexes were selected for a more extensive study based on their capacity inhibiting the rat hind paw edema induced by carrageenin. These selected complexes showed inhibitory action on acute and subacute inflammation with an activity degree higher than that of indometacin. They were also effective inhibitors of primary and secondary lesions in the adjuvant-induced arthritis, with an activity similar to phenylbutazone. These complexes had no topical anti-inflammatory effect. PMID:2242084

Frechilla, D; Lasheras, B; Ucelay, M; Parrondo, E; Craciunescu, G; Cenarruzabeitia, E

1990-08-01

373

Asymmetric synthesis of ?-amino acids via homologation of Ni(II) complexes of glycine Schiff bases. Part 2: Aldol, Mannich addition reactions, deracemization and (S) to (R) interconversion of ?-amino acids.  

PubMed

This review provides a comprehensive treatment of literature data dealing with asymmetric synthesis of ?-amino-?-hydroxy and ?,?-diamino acids via homologation of chiral Ni(II) complexes of glycine Schiff bases using aldol and Mannich-type reactions. These reactions proceed with synthetically useful chemical yields and thermodynamically controlled stereoselectivity and allow direct introduction of two stereogenic centers in a single operation with predictable stereochemical outcome. Furthermore, new application of Ni(II) complexes of ?-amino acids Schiff bases for deracemization of racemic ?-amino acids and (S) to (R) interconversion providing additional synthetic opportunities for preparation of enantiomerically pure ?-amino acids, is also reviewed. Origin of observed diastereo-/enantioselectivity in the aldol, Mannich-type and deracemization reactions, generality and limitations of these methodologies are critically discussed. PMID:24043459

Sorochinsky, Alexander E; Aceña, José Luis; Moriwaki, Hiroki; Sato, Tatsunori; Soloshonok, Vadim

2013-09-17

374

Cellular and computational studies of proteasome inhibition and apoptosis induction in human cancer cells by amino acid Schiff base-copper complexes.  

PubMed

Proliferation and apoptosis pathways are tightly regulated in a cell by the ubiquitin-proteasome system (UPS) and alterations in the UPS may result in cellular transformation or other pathological conditions. Indeed, the proteasome is often found to be overactive in cancer cells. It has also been found that cancer cells are more sensitive to proteasome inhibition than normal cells, and therefore proteasome inhibitors are pursued as antitumor drugs. The use of the proteasome inhibitor Bortezomib for treatment of multiple myeloma and mantle cell lymphoma has proved this principle. Recent studies have suggested that copper complexes can inhibit proteasome activity and induce apoptosis in some human cancer cells. However, the involved molecular mechanism is unknown. In this study, we investigated the biological activities of four amino acid Schiff base-copper(II) complexes by using human breast (MDA-MB-231 and MCF-7) and prostate (PC-3) cancer cells. The complexes C1 and C3, but not their counterparts C2 and C4, inhibit the chymotrypsin-like activity of purified 20S proteasome and human cancer cellular 26S proteasome, cause accumulation of proteasome target proteins Bax and I?B-?, and induce growth inhibition and apoptosis in concentration- and time-dependent manners. Docking analysis shows that C1, but not C2 has hydrophobic, pi-pi, pi-cation and hydrogen bond interactions with the proteasomal chymotrypsin-like pocket and could stably fit into the S3 region, leading to specific inhibition. Our study has identified the mechanism of action of these copper complexes on inhibiting tumor cell proteasome and suggested their great potential as novel anticancer agents. PMID:23142973

Zuo, Jian; Bi, Caifeng; Fan, Yuhua; Buac, Daniela; Nardon, Chiara; Daniel, Kenyon G; Dou, Q Ping

2012-10-15

375

Cellular and computational studies of proteasome inhibition and apoptosis induction in human cancer cells by amino acid Schiff base-copper complexes  

PubMed Central

Proliferation and apoptosis pathways are tightly regulated in a cell by the ubiquitin–proteasome system (UPS) and alterations in the UPS may result in cellular transformation or other pathological conditions. Indeed, the proteasome is often found to be overactive in cancer cells. It has also been found that cancer cells are more sensitive to proteasome inhibition than normal cells, and therefore proteasome inhibitors are pursued as antitumor drugs. The use of the proteasome inhibitor Bortezomib for treatment of multiple myeloma and mantle cell lymphoma has proved this principle. Recent studies have suggested that copper complexes can inhibit proteasome activity and induce apoptosis in some human cancer cells. However, the involved molecular mechanism is unknown. In this study, we investigated the biological activities of four amino acid Schiff base–copper(II) complexes by using human breast (MDA-MB-231 and MCF-7) and prostate (PC-3) cancer cells. The complexes C1 and C3, but not their counterparts C2 and C4, inhibit the chymotrypsin-like activity of purified 20S proteasome and human cancer cellular 26S proteasome, cause accumulation of proteasome target proteins Bax and I?B-?, and induce growth inhibition and apoptosis in concentration- and time-dependent manners. Docking analysis shows that C1, but not C2 has hydrophobic, pi–pi, pi–cation and hydrogen bond interactions with the proteasomal chymotrypsin-like pocket and could stably fit into the S3 region, leading to specific inhibition. Our study has identified the mechanism of action of these copper complexes on inhibiting tumor cell proteasome and suggested their great potential as novel anticancer agents.

Zuo, Jian; Bi, Caifeng; Fan, Yuhua; Buac, Daniela; Nardon, Chiara; Daniel, Kenyon G.; Dou, Q. Ping

2013-01-01

376

Isolation of four new CoII/CoIII and NiII complexes with a pentadentate Schiff base ligand: syntheses, structural descriptions and magnetic studies.  

PubMed

In this paper we report the temperature and pH dependent syntheses and systematic characterization of four new Co(II)/Co(III) and Ni(II) complexes with a pentadentate Schiff base ligand H(3)L obtained by condensing 1,3,-diaminopropan-2-ol with 2-hydroxyacetophenone in 1:2 molar ratio. The room temperature syntheses involving Co(II) and Ni(II) nitrates and the ligand H(3)L lead to the isolation of the dinuclear species [Co(2)L(2)(H(2)O)] (1), and the mononuclear complex [Ni(LH)] (3), respectively, whereas refluxing at basic pH leads to the tetranuclear complexes, [Co(II)(2)Co(III)(2)L(2)(?(3)-OMe)(2)(NO(3))(H(2)O)(2)]NO(3)·2(H(2)O) (2), and [Ni(4)L(2)(?(3)-OMe)(2)(H(2)O)(2)]·2H(2)O (4). 1 is found to be a simple mono alkoxo-bridged Co(III) dinuclear species, whereas 2 and 4 are both rhomb-like tetrameric complexes with double oxo bridges and ?(3)-methoxo bridges, derived from the methanol solvent, in an open dicubane arrangement. Moreover 2 shows six coordinate ordered Co(II) and Co(III) ions and 4 has both six- and five-coordinate Ni(II) centers. Compound 3 is assigned a tentative mononuclear structure based on IR, UV-Vis spectroscopic, (1)H-NMR and ESI mass study results and is supposed to have one Ni(II) center coordinated with a ligand fragment in square planar geometry. The variable temperature magnetic susceptibility study for 2 and 4 is performed which indicate for both 2 and 4 the presence of intracluster dominant ferromagnetic interactions. PMID:21243136

Banerjee, Sambuddha; Nandy, Madhusudan; Sen, Soma; Mandal, Sandip; Rosair, Georgina M; Slawin, Alexandra M Z; Gómez García, Carlos J; Clemente-Juan, Juan M; Zangrando, Ennio; Guidolin, Nicol; Mitra, Samiran

2011-01-17

377

Synthesis and characterization of a series of transition metal complexes with a new symmetrical polyoxaaza macroacyclic Schiff base ligand: X-ray crystal structure of cobalt(II) and nickel(II) complexes and their antibacterial properties  

NASA Astrophysics Data System (ADS)

A new symmetrical [N4O2] hexadentate Schiff base ligand, (E)-N-(pyridin-2-ylmethylene)-2-(3-(2-((E)-pyridin-2-lmethyleneamino)phenoxy)naphthalen-2-yloxy)benzenamine, abbreviated to L, and its complexes of Ni(II), Cu(II), Zn(II), Co(II), Cd(II) and Mn(II) have been synthesized in the presence of metal ions. The complexes were structurally characterized by elemental analyses, IR, UV-Vis, NMR and molar conductivity. The crystal structures of two complexes, [NiL(ONO2)2]·2H2O and [CoLCl2]CH3OH·0.5H2O, have been determined by a single crystal X-ray diffraction study. In these complexes, the ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms. The metal ions complete their six coordination with two coordinated nitrate or chloride ions, forming a distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epid and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The activity data show that the complexes are more potent antibacterials than the parent Schiff base.

Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Valencia, Laura

2013-01-01

378

Synthesis and characterization of a series of transition metal complexes with a new symmetrical polyoxaaza macroacyclic Schiff base ligand: X-ray crystal structure of cobalt(II) and nickel(II) complexes and their antibacterial properties.  

PubMed

A new symmetrical [N4O2] hexadentate Schiff base ligand, (E)-N-(pyridin-2-ylmethylene)-2-(3-(2-((E)-pyridin-2-lmethyleneamino)phenoxy)naphthalen-2-yloxy)benzenamine, abbreviated to L, and its complexes of Ni(II), Cu(II), Zn(II), Co(II), Cd(II) and Mn(II) have been synthesized in the presence of metal ions. The complexes were structurally characterized by elemental analyses, IR, UV-Vis, NMR and molar conductivity. The crystal structures of two complexes, [NiL(ONO2)2]·2H2O and [CoLCl2]CH3OH·0.5H2O, have been determined by a single crystal X-ray diffraction study. In these complexes, the ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms. The metal ions complete their six coordination with two coordinated nitrate or chloride ions, forming a distorted octahedral geometry. The synthesized compounds have antibacterial activity against the three Gram-positive bacteria: Enterococcus faecalis, Bacillus cereus and Staphylococcus epid and also against the three Gram-negative bacteria: Citrobacter freundii, Enterobacter aerogenes and Salmonella typhi. The activity data show that the complexes are more potent antibacterials than the parent Schiff base. PMID:23099161

Keypour, Hassan; Shayesteh, Maryam; Rezaeivala, Majid; Chalabian, Firoozeh; Valencia, Laura

2012-09-28

379

METAL COMPLEXES OF TRIAZINE SCHIFF BASES: SYNTHETIC, THERMODYNAMIC, SPECTROSCOPIC, AND ELECTROCHEMICAL STUDIES ON COMPLEXES OF SOME DIVALENT AND TRIVALENT METAL IONS OF 3-(?-BENZOYLBENZYLIDENHYDRAZINO)-5,6DIPHENYL1,2,4TRIAZINE  

Microsoft Academic Search

Metal complexes of some divalent and trivalent metal ions, viz. Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Pr(III), Nd(III), Sm(III) and Yb(III) with a Schiff base 3-(?-benzoylbenzylidene-hydrazino)- 5,6-diphenyl-1,2,4-triazine (HBZDT) have been investigated potentiometrically, spectrophotometrically and electrochemically and found to have the metal : ligand ratios 1 : 1 and 1 : 2. The dissociation constant of the ligand and the formation constants

Ali Taha

2001-01-01

380

Synthesis and In Vitro Antitumor Activity of Two Mixed-Ligand Oxovanadium(IV) Complexes of Schiff Base and Phenanthroline  

PubMed Central

Two oxovanadium(IV) complexes of [VO(msatsc)(phen)], (1) (msatsc = methoxylsalicylaldehyde thiosemicarbazone, phen = phenanthroline) and its novel derivative [VO (4-chlorosatsc)(phen)], (2) (4-chlorosatsc = 4-chlorosalicylaldehyde thiosemicarbazone), have been synthesized and characterized by elemental analysis, IR, ES-MS, 1H NMR, and magnetic susceptibility measurements. Their antitumor effects on BEL-7402, HUH-7, and HepG2 cells were studied by MTT assay. The antitumor biological mechanism of these two complexes was studied in BEL-7402 cells by cell cycle analysis, Hoechst 33342 staining, Annexin V-FITC/PI assay, and detection of mitochondrial membrane potential (??m). The results showed that the growth of cancer cells was inhibited significantly, and complexes 1 and 2 mainly caused in BEL-7402 cells G0/G1 cell cycle arrest and induced apoptosis. Both 1 and 2 decreased significantly the ??m, causing the depolarization of the mitochondrial membrane. Complex 2 showed greater antitumor efficiency than that of complex 1.

Zhang, Yongli; Wang, Xiangsheng; Fang, Wei; Cai, Xiaoyan; Chu, Fujiang; Liao, Xiangwen; Lu, Jiazheng

2013-01-01

381

Binding Studies of a New Water-Soluble Iron(III) Schiff Base Complex to DNA Using Multispectroscopic Methods  

PubMed Central

A novel iron(III) complex [Fe(SF)](ClO4)3.2H2O; in which SF?=?N,N0-bis{5-[(triphenylphosphonium chloride)-methyl] salicylidene}-o-phenylenediamine) has been synthesized and characterized using different physicochemical methods. The binding of this complex with calf thymus (CT) DNA was investigated by circular dichroism, absorption studies, emission spectroscopy, voltammetric studies, and viscosity measurements. The results showed that this complex can bind to DNA via external and groove binding modes.

Shahabadi, Nahid; Ghasemian, Zeinab; Hadidi, Saba

2012-01-01

382

Gastroprotection Studies of Schiff Base Zinc (II) Derivative Complex against Acute Superficial Hemorrhagic Mucosal Lesions in Rats  

PubMed Central

Background The study was carried out to assess the gastroprotective effect of the zinc (II) complex against ethanol-induced acute hemorrhagic lesions in rats. Methodology/Principal Finding The animals received their respective pre-treatments dissolved in tween 20 (5% v/v), orally. Ethanol (95% v/v) was orally administrated to induce superficial hemorrhagic mucosal lesions. Omeprazole (5.790×10?5 M/kg) was used as a reference medicine. The pre-treatment with the zinc (II) complex (2.181×10?5 and 4.362×10?5 M/kg) protected the gastric mucosa similar to the reference control. They significantly increased the activity levels of nitric oxide, catalase, superoxide dismutase, glutathione and prostaglandin E2, and decreased the level of malondialdehyde. The histology assessments confirmed the protection through remarkable reduction of mucosal lesions and increased the production of gastric mucosa. Immunohistochemistry and western blot analysis indicated that the complex might induced Hsp70 up-regulation and Bax down-regulation. The complex moderately increased the gastroprotectiveness in fine fettle. The acute toxicity approved the non-toxic characteristic of the complex (<87.241×10?5 M/kg). Conclusion/Significance The gastroprotective effect of the zinc (II) complex was mainly through its antioxidant activity, enzymatic stimulation of prostaglandins E2, and up-regulation of Hsp70. The gastric wall mucus was also a remarkable protective mechanism.

Golbabapour, Shahram; Gwaram, Nura Suleiman; Hassandarvish, Pouya; Hajrezaie, Maryam; Kamalidehghan, Behnam; Abdulla, Mahmood Ameen; Ali, Hapipah Mohd; Hadi, A. Hamid A; Majid, Nazia Abdul

2013-01-01

383

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

384

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

385

Synthesis, spectroscopy and electrochemical study of cobalt(III) N2O2 Schiff-base complexes  

Microsoft Academic Search

The complexes [Co(Chel)(PBu3)]ClO4?·?H2O [Chel?=?BFE (bis(1,1,1-trifluoroacetylacetone)ethylenediimine) and BCE (bis(3-chloroacetylacetone)ethylenediimine)] and [Co(Chel)(PPh3)]ClO4?·?H2O, (Chel?=?BBE?=?bis(benzoylacetone)ethylenediimine and BFE), were synthesized and characterized. The spectroscopic and electrochemical properties of cobalt(III) derivatives of BAE (bis(acetylacetone)ethylenediimine) and related ligands have also been investigated. Electronic spectroscopic data indicate that the absorption between 600 and 760?nm in Co(III) BAE complexes is related to the lowest d–d transition. Axial ligands affect

Ali Hossein Kianfar; Solmaz Zargari

2008-01-01

386

Oxovanadium(IV) complexes of bioinorganic and medicinal relevance: Synthesis, characterization and 3D molecular modeling and analysis of some oxovanadium(IV) complexes involving the O, N-donor environment of pyrazolone-based sulfa drug Schiff bases  

NASA Astrophysics Data System (ADS)

Four new oxovanadium(IV) complexes, formed by the interaction of vanadyl sulfate pentahydrate and the Schiff bases derived from 3-methyl-1-phenyl-4-valeryl-2-pyrazolin-5-one and the sulfa drugs, N-(3?-methyl-1?-phenyl-4?-valerylidene-2?-pyrazolin-5?-one)sulfadiazine (L1H), N-(3?-methyl-1?-phenyl-4?-valerylidene-2?-pyrazolin-5?-)sulfaguanidine (L2H), N-(3?-methyl-1?-phenyl-4?-valerylidene-2?-pyrazolin-5?-one)sulphanilamide (L3H) and N?(-3?-methyl-1?-phenyl-4?-valerylidene-2?-pyrazolin-5?-one)sulphamethoxazole (L4H) in aqueous ethanol are described. The resulting complexes were characterized by elemental analyses, molar conductances, magnetic and decomposition temperature measurements, cyclic voltammetry, electron spin resonance, infrared and electronic spectral studies. They have the composition [VO(L)2]·H2O, where LH=Schiff base L1H, L2H, L3H or L4H mentioned above. A square pyramidal structure having a slight ?VO?VO? type interaction has been proposed for these complexes.

Maurya, R. C.; Rajput, S.

2006-08-01

387

Nonlinear optical study of palladium Schiff base complex using femtosecond differential optical Kerr gate and Z-scan techniques  

NASA Astrophysics Data System (ADS)

A femtosecond differential optical Kerr gate (DOKG) and Z-scan techniques, have been applied to investigate the third-order optical nonlinearity of composite film of the coordination complex [PdLPPh3] (L=N-(2-pyridyl)-N?-(salicylidene)hydrazine, PPh3=triphenylphosphine). Film exhibits superior nonlinear optical properties in the near-infrared spectral region. The nonlinear response time and third-order nonlinear optical susceptibility of complex were found to be?90 fs and 3.9×10-10 esu, respectively. The Z-scan result shows that saturable absorption property of the film and its nonlinear absorption coefficient of the sample was found to be -23 cm/GW.

Rudresha, Bada Jayappa; Bhat, Badekai Ramachandra; Ramakrishna, Dileep; Anthony, John Kiran; Lee, H. W.; Rotermund, F.

2012-06-01

388

Synthesis, structural characterization and electrochemical studies of new macrocyclic Schiff base containing pyridine head and its metal complexes  

Microsoft Academic Search

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:13,14-tribenzo-9,12-dioksa-cyclopentadeca-1,5-diene was synthesized by reaction of 2,6-diaminopyridine and 1,2-bis(2-carboxyaldehyde phenoxy)ethane. Then, its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes were synthesized by the template effect by the reaction of 2,6-diaminopyridine and 1,2-bis(2-carboxyaldehyde phenoxy)ethane and Cu(NO3)2·3H2O, Ni(NO3)2·6H2O, Pb(NO3)2, Co(NO3)2·6H2O, La(NO3)3·6H2O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, 1H and 13C

Salih Ilhan; Hamdi Temel; Ismail Yilmaz; Memet Sekerci

2007-01-01

389

Synthesis, characterization and antioxidant activity of water soluble MnIII complexes of sulphonato-substituted Schiff base ligands.  

PubMed

Two new Mn(III) complexes Na[Mn(5-SO(3)-salpnOH)(H(2)O)]5H(2)O (1) and Na[Mn(5-SO(3)-salpn)(MeOH)]4H(2)O (2) (5-SO(3)-salpnOH=1,3-bis(5-sulphonatosalicylidenamino)propan-2-ol, 5-SO(3)-salpn=1,3-bis(5-sulphonatosalicylidenamino)propane) have been prepared and characterized. Electrospray ionization-mass spectrometry, UV-visible and (1)H NMR spectroscopic studies showed that the two complexes exist in solution as monoanions [Mn(5-SO(3)-salpn(OH))(solvent)(2)](-), with the ligand bound to Mn(III) through the two phenolato-O and two imino-N atoms located in the equatorial plane. The E(1/2) of the Mn(III)/Mn(II) couple (-47.11 (1) and -77.80mV (2) vs. Ag/AgCl) allows these complexes to efficiently catalyze the dismutation of O(2)(-), with catalytic rate constants 2.4x10(6) (1) and 3.6x10(6) (2) M(-1)s(-1), and IC(50) values of 1.14 (1) and 0.77 (2) muM, obtained through the nitro blue tetrazolium photoreduction inhibition superoxide dismutase assay, in aqueous solution of pH 7.8. The two complexes are also able to disproportionate up to 250 equivalents of H(2)O(2) in aqueous solution of pH 8.0, with initial turnover rates of 178 (1) and 25.2 (2) mM H(2)O(2) min(-1)mM(-1)catalyst(-1). Their dual superoxide dismutase/catalase activity renders these compounds particularly attractive as catalytic antioxidants. PMID:20129671

Moreno, Diego; Daier, Verónica; Palopoli, Claudia; Tuchagues, Jean-Pierre; Signorella, Sandra

2010-01-06

390

Thermodynamics of adduct formation of cobalt(II) tetraaza Schiff base complexes with organotin(IV)trichlorides  

NASA Astrophysics Data System (ADS)

UV-Vis. spectrophotometric study of the adduct formation of organotin(IV)trichlorides i.e. PhSnCl3 and MeSnCl3 as acceptors with Co(II) tetraaza complexes, such as [Co(ampen)] [N,N'-ethylenebis-(o-amino-?-phenylbenzylideneiminato)cobalt(II)], [Co(campen)] [N,N'-ethylenebis-(5-chloro-o-amino-?-phenylbenzylideneiminato)cobalt(II)], [Co(amaen)] [N,N'-ethylenebis-(o-amino-?-methylbenzylideneiminato)cobalt(II)], [Co(amppn)] [N,N'-propylene bis-(5-chloro-o-amino-?-phenylbenzylideneiminato)cobalt(II)] and [Co(camppn)] [N,N'-propylenebis-(5-chloro-o-amino-?-phenylbenzylideneiminato)cobalt(II)] as donors were studied spectrophotometrically under N2 atmosphere and in N,N'-dimethylformamide solvent. The formation constants and thermodynamic parameters were measured using spectrophotometric titration of adduct formation at various temperatures. The trend of the adduct formations of the cobalt(II) tetraaza complexes with a given organotintrichloride acceptor decreases as follow: [Co(amaen)] > [Co(amppn)] > [Co(ampen)] > [Co(camppn)] > [Co(campen)]. The trend of the formation constants for the studied organotintrichlorides with a given cobalt(II) tetraaza complexes is as follow: PhSnCl3 > MeSnCl3.

Asadi, Zahra; Asadi, Mozaffar; Setoodehkhah, Moslem

2013-08-01

391

Thermodynamics of adduct formation of cobalt(II) tetraaza Schiff base complexes with organotin(IV)trichlorides.  

PubMed

UV-Vis. spectrophotometric study of the adduct formation of organotin(IV)trichlorides i.e. PhSnCl3 and MeSnCl3 as acceptors with Co(II) tetraaza complexes, such as [Co(ampen)] [N,N'-ethylenebis-(o-amino-?-phenylbenzylideneiminato)cobalt(II)], [Co(campen)] [N,N'-ethylenebis-(5-chloro-o-amino-?-phenylbenzylideneiminato)cobalt(II)], [Co(amaen)] [N,N'-ethylenebis-(o-amino-?-methylbenzylideneiminato)cobalt(II)], [Co(amppn)] [N,N'-propylene bis-(5-chloro-o-amino-?-phenylbenzylideneiminato)cobalt(II)] and [Co(camppn)] [N,N'-propylenebis-(5-chloro-o-amino-?-phenylbenzylideneiminato)cobalt(II)] as donors were studied spectrophotometrically under N2 atmosphere and in N,N'-dimethylformamide solvent. The formation constants and thermodynamic parameters were measured using spectrophotometric titration of adduct formation at various temperatures. The trend of the adduct formations of the cobalt(II) tetraaza complexes with a given organotintrichloride acceptor decreases as follow: [Co(amaen)]>[Co(amppn)]>[Co(ampen)]>[Co(camppn)]>[Co(campen)]. The trend of the formation constants for the studied organotintrichlorides with a given cobalt(II) tetraaza complexes is as follow: PhSnCl3>MeSnCl3. PMID:23666357

Asadi, Zahra; Asadi, Mozaffar; Setoodehkhah, Moslem

2013-04-18

392

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

393

Schiff base chemistry of the {ReO}3+ core: structural characterization of the unusual '3 + 2' complex [ReO(?3-OC6H4-CH=NC6H4-2-S)(?2-OC6H4)  

PubMed Central

The reaction of [ReOCl3(PPh3)2] with salicylaldehyde-2-mercaptoanil (1) in methanol yields [ReO(OCH3)(PPh3)(?3-OC6H4CH=NC6H4S)] (3). Reaction of 3 with 2-(2-hydroxyphenyl)benzothiazole (2) produces [ReO(?3-OC6H4CH=NC6H4S)( ?2-OC6H4)] (4) in good yield. Compound 4 may also be prepared directly from the reaction of [ReOCl3(PPh3)2] with excess 1, after prolonged reaction times in the presence of atmospheric oxygen. The structure of 3 exhibits a distorted octahedral Re(V) center coordinated to a terminal oxo-group, a methoxy ligand, a triphenylphosphine ligand, and the N, O and S donors of the tridentate Schiff base ligand. The octahedral geometry of 4 is defined by the terminal oxo-group, the N, O and S donors of the tridentate Schiff base ligand, and the N and O donors of the bidentate 2-(2-hydroxophenyl)benzothiazole ligand. Oxidation and cyclization of the Schiff base salicylaldehyde-2-mercaptoanil to produce 2-(2-hydroxyphenyl)benzothiazole is precedented and in this instance may be driven by the formation of the robust ‘3+2’ complex 4.

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

2010-01-01

394

Iron(III) complexes using NNS reduced Schiff bases and NNOS coordinating tetradentate ligands: Synthesis, structure and catecholase activity  

Microsoft Academic Search

The orange–red colored complexes of the type [Fe(LSB)Cl3], 1, have been synthesized in excellent yields by reacting FeCl3·6H2O with LSB in methanol. Here, LSB is (2-(ethylthio)-N-(pyridin-2-ylmethyl)ethanamine), (LSB1) and (2-(benzylthio)-N-(pyridin-2-ylmethyl)ethanamine) (LSB2). Similarly, FeCl3·6H2O reacted with 2-(((2-(ethylthio) ethyl) (pyridin-2-ylmethyl)amino)methyl)phenol (HL1), 2-(((2-(ethylthio)ethyl)(pyridin-2 ylmethyl)amino)methyl)-4-nitrophenol (HL2), 4-chloro-2-(((2-(ethylthio)ethyl)(pyridin-2-ylmethyl)amino)methyl)phenol (HL3), 2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl) amino)methyl)phenol (HL4), 2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl)amino)methyl) -4-nitrophenol (HL5), and 4-chloro-2-(((2-(benzylthio)ethyl)(pyridin-2-ylmethyl)amino) methyl)phenol (HL6) to give dichloro complexes of the type

Reena Singh; Atanu Banerjee; Kajal Krishna Rajak

2010-01-01

395

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

396

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

397

Synthesis and biological activity of new cycloalkylthiophene-Schiff bases and their Cr(III) and Zn(II) complexes  

Microsoft Academic Search

A series of some novel Ethyl 2-((1-hydroxynaphthalen-2-yl)methyleneamino)-5,6-dihydro-4H-cyclopenta[b]thiopehene-3-carboxylate,\\u000a Ethyl 2-((1-hydroxynaphthalen-2-yl)methyleneamino)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxylate, Ethyl 2-((1-hydroxynaphtalen-2-yl)methyleneamino)-5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophene-3-carboxylate\\u000a and their Cr(III) and Zn(II) complexes have been synthesized. All of these substances have been examined for antibacterial\\u000a activity against pathogenic strains Listeria monocytogenes 4b (ATCC-19115), Staphylococcus aureus (ATCC25923), Proteus OX2 Wrah (ETS.40-A-4), Escherichia coli (ATCC-1280), Salmonella typhi H (NCTC-901.8394), Pseudomonas putida sp., Brucella abortus (A.99, UK-1995) RSKK-03026. Sh.

Aliye Altundas; Nur?en Sar?; Naki Colak; Hatice Ögütcü

2010-01-01

398

One-electron oxidized nickel(II) complexes of bis and tetra(salicylidene) phenylenediamine Schiff bases: from monoradical to interacting Ni(III) ions.  

PubMed

The nickel(II) complexes of the mono and di-nucleating Schiff base ligands H(2)L(OMe), H(2)L(NO2) and H(4)L(bis) respectively were synthesized and characterized. H(2)L(OMe) and H(2)L(NO2) differ from one another by the substituents of the phenylene spacer, electron-donating methoxy or electron-withdrawing nitro groups respectively. X-Ray crystal structure analysis shows that the nickel(II) ion(s) resides within a square planar geometry in each complex. Cyclic voltammetry curves reveal that the electrochemical communication is strongly influenced by the substituent and the solvent. The one-electron oxidized species [Ni(L(OMe))](+) in CH(2)Cl(2) is a phenoxyl radical with partial delocalization of the spin density on a metal orbital (contribution of 6.8%), whereas [Ni(L(NO2))](+) was found to disproportionate once it is generated. A shift of electronic hole is observed in the presence of pyridine: both [Ni(L(OMe))](+) and the one-electron oxidation product of [Ni(L(NO2))] are converted into mononuclear octahedral nickel(III) complexes involving two axially bound pyridines. In the dinickel(II) complex of H(4)L(bis), namely [Ni(2)(L(bis))], the phenylene spacer mediates an electronic communication between the two metallic sites. Single oxidation of [Ni(2)(L(bis))] affords the delocalized phenoxyl radical [Ni(2)(L(bis))](+), whose EPR signature is close to that of [Ni(L(OMe))](+). Double oxidation affords the bis-{Ni(II)-delocalized radical} species [Ni(2)(L(bis))](2+). Each radical is located at a distinct metallic site and a weak but appreciable magnetic interaction exists between the paramagnetic centres. In the presence of pyridine, a complex involving two ferromagnetically coupled nickel(III) ions is obtained. The magnetic coupling has been estimated to 3.7 cm(-1), while the zero field splitting parameters are |D| = 0.012 cm(-1) and E = 0. They are weak, in agreement with the large intermetallic distance (7.7 A) observed in the neutral precursor [Ni(2)(L(bis))]. PMID:19240913

Rotthaus, Olaf; Jarjayes, Olivier; Philouze, Christian; Del Valle, Carlos Pérez; Thomas, Fabrice

2009-01-26

399

Cyanido-bridged Fe(III)-Mn(III) heterobimetallic materials built from Mn(III) Schiff base complexes and di- or tri-cyanido Fe(III) precursors.  

PubMed

The reaction of [Fe(III)L(CN)(3)](-) (L being bpca = bis(2-pyridylcarbonyl)amidate, pcq = 8-(pyridine-2-carboxamido)quinoline) or [Fe(III)(bpb)(CN)(2)](-) (bpb = 1,2-bis(pyridine-2-carboxamido)benzenate) ferric complexes with Mn(III) salen type complexes afforded seven new bimetallic cyanido-bridged Mn(III)-Fe(III) systems: [Fe(pcq)(CN)(3)Mn(saltmen)(CH(3)OH)]·CH(3)OH (1), [Fe(bpca)(CN)(3)Mn(3-MeO-salen)(OH(2))]·CH(3)OH·H(2)O (2), [Fe(bpca)(CN)(3)Mn(salpen)] (3), [Fe(bpca)(CN)(3)Mn(saltmen)] (4), [Fe(bpca)(CN)(3)Mn(5-Me-saltmen)]·2CHCl(3) (5), [Fe(pcq)(CN)(3)Mn(5-Me-saltmen)]·2CH(3)OH·0.75H(2)O (6), and [Fe(bpb)(CN)(2)Mn(saltmen)]·2CH(3)OH (7) (with saltmen(2-) = N,N'-(1,1,2,2-tetramethylethylene)bis(salicylideneiminato) dianion, salpen(2-) = N,N'-propylenebis(salicylideneiminato) dianion, salen(2-) = N,N'-ethylenebis(salicylideneiminato) dianion). Single crystal X-ray diffraction studies were carried out for all these compounds indicating that compounds 1 and 2 are discrete dinuclear [Fe(III)-CN-Mn(III)] complexes while systems 3-7 are heterometallic chains with {-NC-Fe(III)-CN-Mn(III)} repeating units. These chains are connected through ?-? and short contact interactions to form extended supramolecular networks. Investigation of the magnetic properties revealed the occurrence of antiferromagnetic Mn(III)···Fe(III) interactions in 1-4 while ferromagnetic Mn(III)···Fe(III) interactions were detected in 5-7. The nature of these Mn(III)···Fe(III) magnetic interactions mediated by a CN bridge appeared to be dependent on the Schiff base substituent. The packing is also strongly affected by the nature of the substituent and the presence of solvent molecules, resulting in additional antiferromagnetic interdinuclear/interchain interactions. Thus the crystal packing and the supramolecular interactions induce different magnetic properties for these systems. The dinuclear complexes 1 and 2, which possess a paramagnetic S(T) = 3/2 ground state, interact antiferromagnetically in their crystal packing. At high temperature, the complexes 3-7 exhibit a one-dimensional magnetic behavior, but at low temperature their magnetic properties are modulated by the supramolecular arrangement: a three-dimensional antiferromagnetic order with a metamagnetic behavior is observed for 3, 4, and 7, and Single-Chain Magnet properties are detected for 5 and 6. PMID:22385557

Senapati, Tapas; Pichon, Céline; Ababei, Rodica; Mathonière, Corine; Clérac, Rodolphe

2012-03-02

400

Carbon nanotube-enhanced DNA biosensor for DNA hybridization detection using manganese(II)-Schiff base complex as hybridization indicator.  

PubMed

A Mn(II) complex, MnL (L=sodium (E)-3-((1-carboxyethylimino)methyl)-4-hydroxybenzenesulfonate), was synthesized and characterized using elemental analysis and IR spectroscopy. Cyclic voltammetry (CV) and fluorescence spectroscopy were used to investigate the interaction between MnL and salmon sperm DNA. It was revealed that MnL presented high electrochemical activity on glassy carbon electrode (GCE), and it could be intercalated into the double helices of double-stranded DNA (dsDNA). Using MnL as the hybridization indicator, a novel and sensitive electrochemical DNA biosensor based on multiwall carbon nanotubes functionalized with carboxyl groups (MWCNTs-COOH, on which DNA probes were covalently immobilized) was prepared. The target single-stranded DNA (ssDNA) could be quantified ranging from 6.7 x 10(-10)M to 8.4 x 10(-9)M with good linearity (r=0.9922). A detection limit of 1.4 x 10(-10)M (3 sigma, n=9) was achieved. PMID:18950869

Niu, Shuyan; Zhao, Min; Ren, Rui; Zhang, Shusheng

2008-09-18

401

Syntheses, structures, and luminescence behavior of terephthalate bridged lead(II) complexes with tetradentate N-donor Schiff bases  

NASA Astrophysics Data System (ADS)

Three dinuclear compounds of the types [Pb2(L1)2(?-tp)](ClO4)2 (1) and [Pb2(L2)2(?-tp)](ClO4/PF6)2 (2/3) [L1 = N,N?-(bis-(pyridin-2-yl)formylidene)-1,2-ethanediamine; L2 = N,N?-(bis-(pyridin-2-yl)benzylidene)-1,2-ethanediamine and tp = terephthalate dianion] have been synthesized using one-pot reactions of 2:2:1:2 M ratio of Pb(OAc)2?3H2O, L1/L2, piperidinium terephthalate (ptp) and appropriate counter anions in MeOH at room temperature. Compounds 1-3 are characterized on the basis of microanalytical, spectroscopic, thermal and other physicochemical results. X-ray structural analyses of 1-3 reveal each six-coordinated lead(II) center with PbN4O2 chromophore to be bound by four N atoms of L1 in 1 and L2 in 2 and 3 and connected through O atoms of a bis(bidentate) tp bridge. The arrangements of L1/L2 ligand and the tp dianion suggest a void around the metal center presumably occupied by a stereoactive lone pair of electrons that reflect a hemidirected coordination around the metal center. The complexes exhibit reasonable thermal stabilities. In solid states, L1, L2, ptp and 1 display intraligand ? ? ?* fluorescence and 1-3 show ligand-to-metal charge transfer at room temperature.

Roy, Subhasis; Choubey, Somnath; Bhar, Kishalay; Khan, Sumitava; Mitra, Partha; Ghosh, Barindra Kumar

2013-11-01

402

SYNTHESIS AND CHARACTERIZATION OF SOME THIOCYANATO COMPLEXES OF Ni(II), Cu(II), Pd(II), Pt(II), Au(III), Ti(III), AND V(IV) CONTAINING A TRIDENTATE SCHIFF BASE LIGAND  

Microsoft Academic Search

A tridentate ligand HL having a ONN donor sequence has been synthesised by the condensation of ethylenediamine with salicylaldehyde. The ligand undergoes deprotonation during complexation and forms complexes of the compositions, [M(L)(SCN)], [M=Ni(II), Cu(II), Pd(II) and Pt(II), L=deprotonated Schiff base], K[Ti(L)(SCN)3], [Au(L)-(SCN)]Cl and K[V(O)(L)(SCN)2]. These complexes were characterized on the basis of elemental analyses, conductivity and magnetic measurements, NMR, infrared

M. Saidul Islam; M. Akhter Farooque; M. A. K. Bodruddoza

2002-01-01

403

Synthesis, characterization, antibiogram and DNA binding studies of novel Co(II), Ni(II), Cu(II), and Zn(II) complexes of Schiff base ligands with quinoline core  

Microsoft Academic Search

A series of Co(II), Ni(II), Cu(II), and Zn(II) complexes of Schiff base ligands L1H3 and L2H have been prepared. The ligands are synthesized by the condensation of 2-hydroxy-3-formylquinoline with salicyloylhydrazide\\u000a and 2-hydrazinobenzothiazole in absolute ethanol. The prepared complexes were characterized by the analytical and spectral\\u000a techniques. The stoichiometry of the complexes is found to be 1:1. The presence of coordinated

Gurunath S. Kurdekar; Sathisha Mudigoudar Puttanagouda; Naveen V. Kulkarni; Srinivasa Budagumpi; Vidyanand K. Revankar

2011-01-01

404

Synthesis and photoluminescent properties of a Schiff-base ligand and its mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes  

Microsoft Academic Search

Mononuclear Zn(II), Cd(II), Cu(II), Ni(II) and Pd(II) metal complexes of Schiff-base ligand(HL1) derived from 8-acetyl-7-hydroxycoumarin and P-phenylenediamine were prepared and characterized by microanalytical, mass, UV–Vis, IR, 1H NMR, 13C NMR, ESR, conductance and fluorescence studies. The measured low molar conductance values in DMSO indicate that the complexes are non-electrolytes. The structures of the solid complexes under study are established by

E. S. Aazam; A. F. EL Husseiny; H. M. Al-Amri

2010-01-01

405

Copper(II) Schiff base coordination compounds of dien with heterocyclic aldehydes and 2-amino-5-methyl-thiazole: synthesis, characterization, antiproliferative and antibacterial studies. Crystal structure of CudienOOCl2.  

PubMed

A new series of coordination compounds of the starting materials [Cu(dienX(2)Y(2))] and their adducts [Cu(dienXXY(2))(2a-5mt)] (where dien=diethylenetriamine, dienXX=Schiff bases of diethylenetriamine with 2-furaldehyde or 2-thiophene-carboxaldehyde, X=O, S, Y=Cl, Br, NO(3) and 2a-5mt=2-amino-5-methylthiazole) were synthesized by stepwise reactions and their structures were established by C, H, N, Cu analysis, spectroscopic, magnetic and molar conductivity measurements. The isolated compounds are monomers, paramagnetic and electrolytic compounds of the type 1:1. In all cases, the pentadentate Schiff base (dienXX) is bonded in a tridentate fashion through the 3 N atoms. In the CudienXXY(2) compounds the coordination sphere is completed by two Cl or Br or NO(3) groups in a square pyramidal arrangement. The proposed structure for this type of compound was further supported by X-ray diffraction analysis of the compound [Cu(dienOO)Cl(2)]. Its basal plane consists of three Cu-N contacts [2.017(2), 2.025(2) and 2.012(2) A] from dienOO, and the Cl(1) atom, while the Cl(2) atom possesses the apical position, the relevant distances being 2.2732(7) A for Cu-Cl(1) and 2.6051(7) A Cu-Cl(2). In the CudienX(2)Y(2).2a-5mt adducts the coordination sphere of copper is further completed by the nitrogen ring atom of the 2a-5mt, forming an octahedral configuration. The study of the biological activity of the compounds synthesized against a panel of different normal and cancer cell lines (MRC5, HeLa, MCF7, HT-29, OAW42, T47D) and bacteria (E. coli, B. cereus, B. subtilis) showed that the adducts of the type [Cu(dienXXY(2))(2a-5mt)] exhibit increased activity both in cancer cells and in bacteria, compared to the starting material of type [Cu(dienXXY(2))]. PMID:15271502

Chaviara, A Th; Cox, P J; Repana, K H; Papi, R M; Papazisis, K T; Zambouli, D; Kortsaris, A H; Kyriakidis, D A; Bolos, C A

2004-08-01

406

Novel mixed ligand complexes of bioactive Schiff base (E)-4-(phenyl (phenylimino) methyl) benzene-1,3-diol and 2-aminophenol/2-aminobenzoic acid: Synthesis, spectral characterization, antimicrobial and nuclease studies.  

PubMed

A novel bidentate Schiff base ligand has been synthesized using 2,4-dihydroxybenzophenone and aniline. Its mixed ligand complexes of MAB type [M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); HA=Schiff base and B=2-aminophenol/2-aminobenzoic acid] have been synthesized and characterized on the basis of spectral data UV-Vis, IR, (1)H NMR, FAB-Mass, EPR, SEM and magnetic studies. All the complexes were soluble in DMF and DMSO. Elemental analysis and molar conductance values indicate that the complexes are non-electrolytes. HA binds with M(II) ions through azomethine and deprotonated phenolic group and B binds through the primary amine group and deprotonated phenolic/carboxylic groups. Using FAB-Mass the cleavage pattern of the ligand (HA) has been established. All the complexes adopt octahedral geometry around the metal ions. It has been confirmed with the help of UV-Vis, IR, (1)H NMR and FAB-Mass spectral data. DNA binding activities of the complexes 1d and 2d are studied by UV-Vis spectroscopy and cleavage studies of Schiff base ligand and its complexes 1d and 2d have been by agarose gel electrophoresis method. In vitro biological activities of the free ligand (HA) and their metal complexes (1a-1e and 2a-2e) were screened against few bacteria, Escherichia coli, Staphylococcus saphyphiticus, Staphylococcus aureus, Pseudomonas aeruginosa and fungi Aspergillus niger, Enterobacter species, Candida albicans by well diffusion technique. PMID:23981416

Subbaraj, P; Ramu, A; Raman, N; Dharmaraja, J

2013-08-08

407

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

408

Synthesis, characterization and biological evaluation of Fe (III), Co (II), Ni(II), Cu(II), and Zn(II) complexes with tetradentate Schiff base ligand derived from protocatechualdehyde with 2-aminophenol.  

PubMed

Schiff base ligand (H(3)L) was prepared from the condensation reaction of protochatechualdehyde (3,4-dihydroxybenzaldhyde)with 2-amino phenol. From the direct reaction of the ligand (H(3)L) with Co(II), Ni(II) and Cu(II) chlorides, and Fe(III)and Zn(II)nitrates in 2 M/1 L molar ratio, the five new neutral complexes were prepared. The characterization of the newly formed compounds was done by (1)H NMR, UV-Vis, and IR spectroscopy and elemental analysis. The in vitro antibacterial activity of the metal complexes was studied and compared with that of free ligand. PMID:22576963

Hassan, A M; Nassar, A M; Hussien, Y Z; Elkmash, A N

2012-05-11

409

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

410

Hydrothermal and sonochemical synthesis of a nano-sized nickel(II) Schiff base complex as a precursor for nano-sized nickel(II) oxide; spectroscopic, catalytic and antibacterial properties  

Microsoft Academic Search

The Ni(II) complexes [Ni(L)2](ClO4)2 (1) and [Ni(L)2(NO3)2] (2), where L is the Schiff base ligand of 4,5,9,13,14-pentaaza-benzo[b] triphenylene, were synthesized and characterized by\\u000a physico-chemical and spectroscopic methods. Nano-sized particles of (1) were prepared both by sonochemistry (3) and solvothermal (4) methods. NiO nanoparticles were obtained by calcination of the nano-structure complexes at 500 °C. The structures of the\\u000a nano-sized compounds were

Lotf Ali Saghatforoush; Robabeh Mehdizadeh; Firoozeh Chalabian

2010-01-01

411

Synthesis and biological activity of Magnesium(II) complexes of heptaaza Schiff base macrocyclic ligands; 1 H and 13 C chemical shifts computed by the GIAO-DFT and CSGT-DFT methodologies  

Microsoft Academic Search

Two new pendant armed Schiff base macrocyclic complexes, [MgL1](ClO4)2 (1), and [MgL2](ClO4)2 (2), have been prepared via cyclocondensation of 2,6-diformylpyridine and 2,6-diacetylpyridine with two hexadentate hexaamines,\\u000a ten and tmen, in the presence of Mg(II) ion. The ligands are 15-membered pentaaza macrocycles having two 2-aminoethyl pendant\\u000a arms. The newly prepared complexes are investigated by IR, 1H NMR, 13C{1H} NMR, DEPT(135), COSY(H,

Hamid Khanmohammadi; Hassan Keypour; Mehdi Salehei Fard; Mohammad H. Abnosi

2009-01-01

412

Synthesis, characterisation and crystal structures of a few coordination complexes of nickel(II), cobalt(III) and zinc(II) with N?-[(2-pyridyl)methylene]salicyloylhydrazone Schiff base  

Microsoft Academic Search

Four new coordination complexes, NiII(L)2 (1), [CoIII(L)2]ClO4 (2), [Zn(HL)(L)]ClO4·H2O (3) and [Zn(L)2][Zn(L)(HL)]ClO4·7H2O (4) (where L is a monoanion of a Schiff base ligand, N?-[(2-pyridyl)methylene]salicyloylhydrazone (HL) with NNO tridentate donor set), have been synthesised and systematically characterised by elemental analysis, spectroscopic studies and room temperature magnetic susceptibility measurements. Single crystal X-ray diffraction analysis reveals that 1 is a neutral complex, while

Brajagopal Samanta; Joy Chakraborty; Shyamapada Shit; Stuart R. Batten; Paul Jensen; Jason D. Masuda; Samiran Mitra

2007-01-01

413

Synthesis, Physicochemical, and Antimicrobial Screening Studies of Complexes of Co(II), Ni(II), Cu(II), and Zn(II) with 18-membered Schiff Base Octaazamacrocyclic Ligand  

Microsoft Academic Search

A [2 + 2] condensation reaction between 1,8-diaminonaph-thalene and N,N?-diacetylhydrazine in 1:1 molar ratio in methanol resulted in a novel Schiff base macrocyclic ligand, (L): 7,9:16,18-dinaphthyl-1,3,4,6,10,12,13,15-octaazacyclooctadecane-1,5,10,14-tetraene. Metal complexes have been synthesized by the reaction of L with the corresponding metal salts. The results of elemental analyses, ESI-mass, and Job's method ascertain their stoichiometry while the spectral data obtained from H

Tahir Ali Khan; Sultana Naseem; Rafat Hajra; Mohammad Shakir

2010-01-01

414

Chiral vanadium(V) complexes with 2-aminoglucose Schiff-base ligands and their solution configurations: synthesis, structures, and DFT calculations.  

PubMed

The sugar-modified Schiff-base ligands derived from benzyl 2-deoxy-2-salicylideneamino-?-D-glucopyranoside (H2L(5-Br) and H2L(3-OMe)) were used to prepare the chiral oxidovanadium(V) complexes [VO(L(5-Br))(OMe)] (1) and [VO(L(3-OMe))(OMe)] (2) which can be isolated from a methanol solution as the six-coordinate complexes with an additional methanol ligand [VO(L(5-Br))(OMe)(MeOH)] (1-MeOH) and [VO(L(3-OMe))(OMe) (MeOH)] (2-MeOH). Both complexes crystallize in the orthorhombic space group P2(1)2(1)2(1) together with two solvent molecules of methanol as 1-MeOH·2MeOH and 1-MeOH·2MeOH. In both crystal structures, only diastereomers with A configuration at the chiral vanadium centre (OC-6-24-A) are observed which corresponds to an cis configuration of the oxido group at the vanadium centre and the benzyl group at the anomeric carbon of the sugar backbone. Upon recrystallization of 2-MeOH from chloroform, the five-coordinate complex 2 was obtained which crystallizes in the monoclinic space group P2(1) with one co-crystallized chloroform molecule (2·CHCl3). For the chiral vanadium centre in 2·CHCl3, a C configuration (SPY-5-43-C) is observed which corresponds to an trans structure as far as the orientations of the oxido and benzyl groups are concerned. (1)H and (51)V NMR spectra of 1 and 2 indicate the presence of two diastereomers in solution. Their absolute configurations can be assigned based on the magnetic anisotropy effect of the oxidovanadium group. This effect leads to significant differences for the (1)H NMR chemical shifts of the H-2 (1.1 ppm) and H-3 protons (0.3 ppm) of the glucose backbone of the two diastereomers, with the downfield shift observed for the H-2 proton of the C-configured and the H-3 proton of the A-configured diastereomer at the vanadium centre. For 1 and 2 the difference between the (51)V NMR chemical shifts of the two diastereomers is 30 and 28 ppm, respectively. Also in the (13)C NMR significant chemical shift differences between the two diastereomers are observed for the carbon atoms C2 (2 ppm) and C3 (4 ppm). DFT calculations of the NMR chemical shift parameters have been performed which are in good agreement with the experimental data. Moreover, the isomerization mechanism between the diastereomers is analysed on the basis of DFT calculations which indicate the required presence of methanol molecules as protic donors. PMID:23760018

Mohammadnezhad, Gholamhossein; Böhme, Michael; Geibig, Daniel; Burkhardt, Anja; Görls, Helmar; Plass, Winfried

2013-09-01

415

Synthesis and properties of new phosphorescent red light-excitable platinum(II) and palladium(II) complexes with Schiff bases for oxygen sensing and triplet-triplet annihilation-based upconversion.  

PubMed

New Pt(II) and Pd(II) complexes with donor-acceptor Schiff bases are conveniently prepared in only two steps. The complexes efficiently absorb in the red part of the spectrum (? > 10(5) M(-1) cm(-1)) and show moderate to strong room-temperature phosphorescence in the near-infrared (NIR) region. Particularly, Pt(II) complexes possess phosphorescence quantum yields (?) of ~10%, but the emission of the respective Pd(II) complexes is less efficient (? ? 1%-2%). The complexes exhibit solvatochromic behavior, in which the absorption and emission spectra shift bathochromically in polar solvents. The Pt(II) complexes are embedded in polystyrene to produce oxygen-sensing materials. The Pd(II) and Pt(II) complexes are demonstrated to be efficient sensitizers in triplet-triplet annihilation-based upconversion systems. PMID:23231719

Borisov, Sergey M; Saf, Robert; Fischer, Roland; Klimant, Ingo

2012-12-11

416

Manganese(III,IV) and manganese(III) oxide clusters trapped by copper(II) complexes.  

PubMed

Reactions of quinquedentate Schiff base ligands with Mn and Cu ions afforded icosa- and hexadecanuclear mixed-metal clusters in which dinuclear CuII complexes trapped oxo-bridged [MnIII8MnIV4O12] and [MnIII6O6] cores, respectively. Maximum entropy method analysis for synchrotron X-ray diffraction data was used to determine the oxidation states of the Mn ions. PMID:17432848

Yamashita, Satoshi; Shiga, Takuya; Kurashina, Masashi; Nihei, Masayuki; Nojiri, Hiroyuki; Sawa, Hiroshi; Kakiuchi, Toru; Oshio, Hiroki

2007-04-14

417

Structural, spectroscopic characterization and EPR spectra of nitrato-?-[N,N'-ethylenebis(3-methoxysalicylideneimine) Cu(II)Ag(I)] complex.  

PubMed

A novel heterodinuclear complex formed by the reaction of silver nitrate with Schiff base complex of copper(II) has been synthesized and characterized by Infrared (IR), ultraviolet-visible (UV-VIS), electron paramagnetic resonance (EPR) and X-ray diffraction methods. Preparation and crystal structure of the heterodinuclear complex, LCuAgNO3, (L=N,N'-ethylenebis(3-methoxysalicylideneimine) are reported. The crystal structure consists of ordered dinuclear units with CuII and AgI ions are bridged by two oxygen atoms of Schiff base ligand. The copper(II) ion has a distorted square-planar geometry involving the N2O2 donor set of Schiff base ligand. The g-values were calculated for title complex both in polycrystalline state at 298 K and in frozen DMF (113 K). The evaluated metal-ligand bonding parameters showed strong in-plane ? bonding. PMID:23099175

Senyüz, Nuray; Y?lmaz, Betül; Bat?, Hümeyra; Bozkurt, Esat; Büyükgüngör, Orhan

2012-09-28

418

Structural, spectroscopic characterization and EPR spectra of nitrato-?-[N,N'-ethylenebis(3-methoxysalicylideneimine) Cu(II)Ag(I)] complex  

NASA Astrophysics Data System (ADS)

A novel heterodinuclear complex formed by the reaction of silver nitrate with Schiff base complex of copper(II) has been synthesized and characterized by Infrared (IR), ultraviolet-visible (UV-VIS), electron paramagnetic resonance (EPR) and X-ray diffraction methods. Preparation and crystal structure of the heterodinuclear complex, LCuAgNO3, (L = N,N'-ethylenebis(3-methoxysalicylideneimine) are reported. The crystal structure consists of ordered dinuclear units with CuII and AgI ions are bridged by two oxygen atoms of Schiff base ligand. The copper(II) ion has a distorted square-planar geometry involving the N2O2 donor set of Schiff base ligand. The g-values were calculated for title complex both in polycrystalline state at 298 K and in frozen DMF (113 K). The evaluated metal-ligand bonding parameters showed strong in-plane ? bonding.

?enyüz, Nuray; Y?lmaz, Betül; Bat?, Hümeyra; Bozkurt, Esat; Büyükgüngör, Orhan

2013-01-01

419

A new hydrogen-bonded pseudo-dimer Mn(III) Schiff base complex. The synthesis, X-ray structure and spectroscopic studies.  

PubMed

A new hydrogen-bonded pseudo-dimer, [Mn(III)L1(CH(3)CH(2)OH)](2)(ClO(4)) (1) (L1 = N,N'-bis(2-hydroxy-1-naphthalidenato)-1,2-diaminopropane) has been synthesized and characterized by UV-vis, IR, elemental analysis and crystal structure analysis. The single crystal X-ray diffraction reveals that the structure affords an elongated octahedral MnN(2)O(4) coordination environment, geometry with the four donor atoms of the tetradentate Schiff base in the equatorial plane and with two ethanol molecule in axial positions with Mn-O = 2.265(2) and 2.266(2) ?. PMID:21816668

Gungor, Elif; Kara, Hulya

2011-07-23

420

Determination of stability constants of intermediates by coordination capillary GLC. Chiral complexes of Ni II and Cu II with Schiff's bases (1 R , 2 R )- N,N? -bis(3?- tert -butylsalycilidene)diaminocyclohexane and (1 R ,2 R )- N,N? -bis[(4-hydroxy[2.2]paracyclophanyl)-5-methylene]diaminocyclohexane as GLC phases  

Microsoft Academic Search

Chiral NiII and CuII salen complexes dissolved in the polymethylphenylsiloxane phase OV-17 were used as the phases for capillary chromatography.\\u000a Chiral salen lignads are Schiff's bases obtained from salicylaldehyde (SA) and (1R,2R)-diaminocyclohexane and Schiff's bases obtained by condensation of (1R,2R)- or (1S,2S)-diaminocyclohexane with (R)-4-hydroxy-5-formyl[2.2]paracyclophane (HFPC). The stability constants of the intermediates were calculated from the retention\\u000a times. The complexes based

S. A. Orlova; N. S. Ikonnikov; T. D. Churkina; V. I. Rozenberg; A. A. Aleshkin; D. Yu. Antonov; Yu. N. Belokon

1997-01-01