Copper(II) complexes of coumarin-derived Schiff bases and their anti-Candida activity (original) (raw)
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Dalton Transactions, 2010
The coordination modes of copper(II) complexes of Schiff base-derived coumarin ligands, which had previously shown good anti-Candida activity, were investigated by pH-potentiometric and UV-Vis spectroscopic methods. These studies confirmed the coordination mode of the ligands to be through the N of the imine and deprotonated phenol of the coumarin-derived ligand in solution. In addition, the more active complexes and their corresponding ligands were investigated in the presence of copper(II) in liquid and frozen solution by ESR spectroscopic methods. A series of secondary amine derivatives of the Schiff base ligands, were isolated with good solubility characteristics but showed little anti-Candida activity. However, cytotoxicity studies of the secondary amines, together with the copper complexes and their corresponding ligands, against human colon cancer and human breast cancer cells identified the chemotherapeutic potential of these new ligands. Structures of Schiff bases 1a-1k and their corresponding secondary amines 3a-3k showing the numbering system used in the assignment of 1 H and 13 C NMR spectra.
Inorganic Chemistry
Six transition M(II) complexes [where M = Cu(II), Zn(II), Cd(II), Co(II),Ni(II) and Pd (II)] of the organic ligand , 4-methyl-7-(salicylidineamino)-coumarin HL I have been synthesized and characterized by a variety of physicochemical techniques. An octahedral structure is proposed for theCd(II) complex, a square planar for Co(II), Ni(II) and Pd (II) complexeswhile a tetrahedral structure for the Zn(II) complex. The ligand HL I and itsmetal complexes are screened for their antimicrobial activities against A.niger fungi and E. coli bacteria. The studies demonstrated that metallationcan increase the antibacterial activity rather than the free ligand. TheCd(II) complex exhibited the maximum bacterial inhibition, however, nosignificant antifungi activity of the organic ligand HL or its complexeswere demonstrated
Journal of Molecular …, 2010
A series of Co(II), Ni(II) and Cu(II) complexes have been synthesized with Schiff bases derived from 2hydroxy-1-naphthaldehyde and 2-oxo-2H-chromene-3-carbohydrazide/6-bromo-2-oxo-2H-chromene-3-carbohydrazide. The chelation of the complexes has been proposed in the light of analytical, spectral (IR, UV-Vis, 1 H NMR, ESR, FAB-mass and fluorescence), magnetic and thermal studies. The measured molar conductance values indicate that, the complexes are non-electrolytic in nature. The redox behavior of the complexes was investigated with electrochemical method by using cyclic voltammetry. The Schiff bases and their metal complexes have been screened for their in vitro antibacterial (Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Salmonella typhi) and antifungal activities (Candida albicans, Cladosporium and Aspergillus niger) by MIC method. The DNA cleavage is studied by agarose gel electrophoresis method.
2011
A new series of Co(II), Ni(II) and Cu(II) complexes of the type ML•2H 2 O of Schiff-bases derived from msubstituted 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.
European journal of …, 2008
Novel Schiff base ligand (E)-2-((3-(benzyloxypyridinylimino) methyl)-4-bromophenol (HL) was synthesized. Using this Schiff base ligand, two new copper(II) complexes, C1 and C2 were prepared. Analytical techniques such as IR, 1 H NMR, 13 C NMR, mass, UV-visible spectroscopy, molar conductivity, magnetic measurement, ESR and TGA-DTA were used to characterize the ligand HL and its copper complexes. From the ESR spectra, square planar geometry was proposed for C1 and C2. The synthesized ligand, HL along with its copper(II) complexes were subjected to test their in vitro biological efficacies against four bacterial strains Escherichia coli, Salmonella typhi, Bacillus subtilis and Staphylococcus aureus and two antifungal strains Candida albicans and Aspergillus niger. The results obtained from this work suggest that the studied metal complexes are very effective in biological activities than its ligand. The anthelmintic test of the ligand HL and copper complexes against earthworms, Pheretima posthuma are also investigated.
The Journal of Engineering and Exact Sciences, 2019
Quantitative Structure Activity Relationship (QSAR) study was carried out on Copper Schiff base complexes. Multiple Linear Regression analysis and genetic function algorithms was employed to derive QSAR model for better activity. The derived QSAR model having Squared Correlation Coefficient R 2 = 0.8345, Cross Validation Squared Correlation Coefficient Q 2 = 0.6681 and predicted R squared (R 2 pred)= 0.5980. The robustness of the derived model was confirmed by internal and external cross validation techniques. The QSAR model indicate that the descriptors (MATS4p) Moron autocorrelation of lag 4 weighed by polarizability, (RCI) Ring Complexity index, (G2m) 2 nd component symmetry directional WHIM index/weighted by mass, BI0 [N-O] Presence/absence of NO at topological distance 10 and (nF) Number of Fluorine atoms plays an important role in predicting the activities against anti-candida albican. The result obtained in this study was used in designing more potent Copper Complexes as anti-candida albican agents.
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 Inorganic Biochemistry, 2015
The new Cu(II) complexes of 1/2/3-(bromophenyl)-3-(1,7,8,9-tetramethyl-3,5-dioxo-4-azatricyclo[5.2.1.0 2,6 ] dec-8-en-4-yl)thiourea derivatives have been synthesized. The spectroscopic studies together with density functional theory calculations of Cu(II) complexes revealed that two parent ligands coordinate to the copper cation in bidentate fashion via thiocarbonyl S and deprotonated N atoms forming rarely observed four-membered chelate ring, with nearly planar [CuN 2 S 2 ] moiety. In solid state, the mononuclear complex is formed for thiourea derivative with 3-bromophenyl, whereas for Cu(II) connection with 2-and 4-bromophenyl-thioureas the formation of dinuclear complexes is observed, the latter formed by the stacking of mononuclear complexes. The microbiological activity of novel compounds has been evaluated. The Cu(II) complex with 4-bromophenyl ring connected to the thiourea moiety showed significant inhibition against standard strains of S. aureus and S. epidermidis. The range of minimal inhibitory concentration values is 2-4 μg/mL. That compound exhibited antibiofilm potency and effectively inhibited the formation of biofilm of methicillin-susceptive strain of S. epidermidis ATCC 12228. Moreover, the cytotoxicity against the MT-4 cells of all obtained complexes has been evaluated. The complexes turned out to be non-cytotoxic for exponentially growing MT-4.
Spectrochimica Acta Part A: …, 2010
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.