Synthesis, Characterisation and Antimicrobial Activity of Dimeric and Monomeric Copper(II)-Schiff base Complexes (original) (raw)
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Transition Metal Chemistry, 2000
Neutral complexes of Cu II have been synthesised from the Schiff bases derived from salicylidene-4-aminoantipyrine and PhNH 2 /substituted anilines. The structural features have been determined from their microanalytical, i.r., u.v.vis., 1 H-, 13 C-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 respectively. The electrochemical behaviour of the complexes in MeCN at 298 K was studied. The kinetic parameters were determined and are discussed. The X-band e.s.r. spectra of the complexes in DMSO at 300 and 77 K were recorded and their salient features are reported. The powder XRD diffraction patterns for all the complexes are found to be similar. The antimicrobial activity of the ligands and their copper complexes against the bacteria Staphylococcus aureus, Klebsiella pneumoniae, Salmonella typhi, Pseudomonas aerugenosa and Bacillus subtilis are also reported. The complexes have higher activities than those of the free Schiff bases. Moreover, they have higher activity than the control (ampicillin) except for Klebsiella pneumoniae and Pseudomonas aerugenosa.
Polyhedron, 2011
Coordination compounds of Cu(II), VO(II), Ni(II), and Mn(II) with the Schiff base obtained through the condensation of 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one with 3-formyl-6-methyl-chromone were synthesized. The characterization of the newly formed compounds was done by 1 H NMR, UV-Vis, IR, ESR spectroscopy, elemental analysis and molar electric conductibility. The crystal structure of 1-phenyl-2,3-dimethyl-4-(N-3-formyl-6-methyl-chromone)-3-pyrazolin-5-one (HL) has been determined by X-ray diffraction studies, as well as the one of its copper(II) complex [CuL(OAc)]ÁCH 3 OH which contains an anionic ligand and an acetate in the coordination sphere of the metal. The single crystal X-ray structure for (HL) was analyzed for its various weak H-bonding and dimeric association.
A rapid, efficient, clean and environmentally benign exclusive synthesis of Schiff bases as new ligands and their complexes with Cu(II) have been developed using condensation of salicylaldehyde and amoxicillin (L 1 ), cephalexin (L 2 ), sulphamethoxazole (L 3 ) and trimethoprim (L 4 ) efficiently in analcoholic suspension medium using alkali catalyst with excellent yields under microwaves irradiation. This method provides several advantages such as environmental friendliness, simple work-up procedure, short reaction times, non-hazardous and excellent yield of products.The results are compared with conventional methods for their yield and reaction time. The Schiff base ligands and the complexes were characterized by micro-analytical, thermo-gravimetric, magnetic and spectroscopic studies.Allthe Schiff bases were bidentate (NO donor) ligands. Salicylidenesulphamethoxazole-Cu(II) monohydrate was five co-ordinate whereas all other complexes were found to be six co-ordinate dihydrates and ML 2 [1:2 (metal: ligand) ratio] type. The complexes are coloured and stable in air. All the complexes under investigation possess antibacterial activity. The antibacterial activity showed the following trend: Cu(II)-complexes ˃ Schiff base ligands ˃ parent drugs.
Novel potential monovalent tridentate ligands such as 4-hydroxy-3-methoxybenzylidene-2-aminoethanoicacid (HMBAEA) and 4-hydroxy-3-methoxybenzylidene-2-amino-5-bromobenzoic acid (HMBABrBA) were prepared and their structures were derived on the basis of various techniques like infrared, electronic, 1 HNMR and 13 CNMR spectroscopy. The chelating ability of these ligands towards Cu(II) ion was explored by synthesizing and characterizing the metal complexes. Geometries of the complexes were established by magnetic moment studies. The antibacterial and antifungal activity of the ligands and complexes were studied using different bacterial and fungal growth by well cut method. Key words: 4-hydroxy-3-methoxy benzaldehyde, 2-amino-5-bromobenzoic acid, transition metal complexes.
Journal of the Serbian Chemical Society, 2007
Three new copper complexes of mixed ligands derived from Schiff bases (condensation of p-aminoacetanilide and substituted benzaldehydes) with 1,10-phenanthroline have been synthesized and characterized by elemental analysis, IR, UV-Vis, magnetic moments, conductivity and electrochemical measurements. The spectral techniques suggest that all the copper complexes exhibit octahedral geometry. The low electrical conductance of the complexes supports their neutral nature. The monomeric nature of the complexes was assessed from their magnetic susceptibility values. The in vitro biological screening effects of the investigated compounds were tested against the bacteria Escherichia coli, Staphylococcus aureus, and Salmonella typhi and the fungi Rhizopus stolonifer and Candida albicans by the serial dilution method. A comparative study of the MIC values of the Schiff bases and their copper complexes indicates that the metal complexes exhibited higher antibacterial activity than the free liga...
Bulletin of the Chemical Society of Ethiopia
The synthesis, characterization and antimicrobial activity of Cu(II) complexes of some p-substituted aniline Schiff base ligands have been carried out. The Schiff bases were obtained from salicylaldehyde and o-vanillin. The Cu(II) complexes have been characterized by elemental analysis, conductivity measurement, infrared and electronic spectral data. The complexes were obtained either as metal chelates [Cu(L)2] or Schiff base adducts (CuCl2.2LH).xH2O. The metal chelates were non-electrolytes while the Schiff base adducts exhibited 1:1 or 2:1 electrolytes in methanol. The Cu(II) complexes exhibited slight antimicrobial activity against Escherichia coli ATCC® 8739™*, Staphylococcus aureus subsp. aureus ATCC® 6538™*, Bacillus subtilis subsp. spizizenii ATCC® 6633™* and Candida albicans ATCC® 2091™*. The complexes exhibited significant antifungal activity. KEY WORDS: Metal Chelates, Schiff bases, Adducts, Cu(II) complexes, Salicylaldimines Bull. Chem. Soc. Ethiop. ...
Physiochemical and Antibacterial Activity Investigation on Noble Schiff Base Cu(II) Complex
American Journal of Heterocyclic Chemistry, 2017
Schiff base ligand and its Cu(II) complex had been synthesized by the condensation reaction of isatin with amino acids (cysteine / glycine / leucine / alanine). The Structure and spectral properties of ligand and complex were confirmed by UV, FT-IR and some physiochemical measurements. The spectral properties showed that it was a distorted tetrahedral geometry with a tridentate ligand and chloride ion. IR spectral studies show the binding sites of the Schiff base ligand with the metal ion. Molar conductance data and magnetic susceptibility measurements give evidence for monomeric and non-electrolytic nature of the complexes. The Schiff base Cu(II) complex was subjected to antimicrobial studies screened by employing the Disc Diffusion method. All the synthesized complexes showed strong antibacterial activity.
Bioconjugate Chemistry, 2014
A new series of six Schiff bases derived from S-methyldithiocarbazate (SMDTC) and S-benzyldithiocarbazate (SBDTC) with methyl levulinate (SMML, SBML), levulinic acid (SMLA, SBLA) and 4-carboxybenzaldehyde (SM4CB, SB4CB) were reacted with copper(II), producing complexes of general formula ML 2 (M = Cu(II), L = ligand). All compounds were characterized using established physico-chemical and spectroscopic methods. Crystal structures were determined for three Schiff bases (SMML, SBML, SBLA) and two Cu(II) complexes (Cu(SMML) 2 and Cu(SMLA) 2). In order to provide more insight into the behaviour of the complexes in solution, electron paramagnetic resonance (EPR) and electrochemical experiments were performed. The parent ligands and their respective copper(II) complexes exhibited moderate antibacterial activity against both Gram-negative and Gram-positive bacteria. The most active ligand (SB4CB) and its analogous S-methyl derivative (SM4CB) were conjugated with various vector moieties: polyarginines (R1, R4, R9 and RW9), oligoethylene glycol (OEG) and an efflux pump blocker, phenylalanine-arginine-β-naphthylamide (PAβN). Nonarginine (R9) derivatives showed the most encouraging synergistic effects upon conjugation and complexation with copper ion including enhanced water solubility, bacteria cell membrane permeability and bioactivity. These Cu(II)-R9 derivatives display remarkable antibacterial activity against a wide spectrum of bacteria and in particular, are highly efficacious against Staphylococcus aureus with minimum inhibition concentration (MIC) values of 0.5-1 µM. This pioneer study clearly indicates that the conjugation of cell-penetrating peptides (CPPs) to dithiocarbazate compounds greatly enhances their therapeutic potential.
Two new Schiff base tridentate ligands (E)-2-(3-hydroxy-4methoxybenzalidene)-N 4 -methylhydrazinecarbothioamide (L 4 ) and (E)-2-(3,4-dihydroxybenzalidene)-hydrazinecarboamide (L 5 ) derived from simple condensation of 3-hydroxy-4-methoxybenzaldehyde and 3,4-dihydroxybenzaldehyde with N 4 -methylthiosemicarbazide and semicarbazide hydrochloride respectively. Schiff base Copper (II) complexes (4a-b, 5a-b) derived from Schiff base bidentate ligand L 4 and L 5 with CuCl 2 .2H 2 O (4a and 5a) and CuBr 2 (4b and 5b) respectively. The synthesized Schiff bases have been characterized by microanalysis, FT-IR, 1 H NMR and 13 C NMR. The copper (II) complexes have been characterized by microanalysis and FT-IR. All Schiff bases and copper (II) complexes showed good activity against the Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Salmonella paratyphi) and fungi (Aspergillus niger and Candida albicans). The antimicrobial results also indicate that the copper (II) complexes are better antimicrobial agents as compared to the Schiff bases.