Synthesis, characterization, X-ray crystallography and DNA binding activities of Co(III) and Cu(II) complexes with a pyrimidine-based Schiff base ligand

A new pyrimidine based ‘NNO’ tridentate ligand 2,4-dihydroxyacetophenone-4,6-dimethyhydrazino pyrimidine (H2MHyP) (complex I) has been synthesized and characterized by elemental analyses, mass, IR 1H NMR spectra and X-ray crystallographic studies. The Coordination mode of the synthesized ligand has been established by solid state isolation and physico-chemical identification of Co(III) and Cu(II) complexes, [Co(HMHyP)2]Cl (complex II), [Co(HMHyP)2]Br (complex III) and [Cu(HMHyP)]NO3 (complex IV) respectively. All the reported coordination complexes are 1:1 electrolytic cationic species and the ligand behaves as a monodeprotonated ‘NNO’ tridentate one in all the complex species. IR spectral data indicate that the coordination of each of the metal centre of the complexes occurs through the pyrimidine nitrogen, azomethine nitrogen and hydroxyl oxygen atoms. X-ray crystallographic data have authenticated a CoN4O2 octahedral coordination for II and III (Triclinic (P-1) and Monoclinic (P21/n), respectively) and a CuN2O2 square planar coordination for IV (Triclinic (P-1)). All the synthesized compounds were tested for their DNA binding abilities and their mode of binding with DNA. Compounds II, III & IV show potential DNA binding activities with Salmon Testis DNA.PostprintPeer reviewe

Synthesis, spectroscopy and structural elucidation of two new CoII and NiII complexes of pyrazole derived heterocyclic Schiff base ligand as potential anticancer and photocatalytic agents

Dr. Arunima Biswas has received research grant from West Bengal DBT, vide grant no. (676/(Sanc.)/BT/(Estt.)/RD27/2016).Two new complexes I and II of general composition, [ML3]X2.nH2O (where, M = CoII and NiII for I and II, respectively, L = MPAFA, X = Br and n = 2) were synthesized from a pyrazolyl Schiff base ligand, MPAFA (L). I and II were characterised through several physico-chemical and spectroscopic techniques, viz., C, H, N analyses, estimation of metal contents, conductance and magnetic susceptibility measurements, IR, electronic and fluorescence spectral studies. Both the reported coordination complexes were cationic in nature and behaved as 1:2 electrolytes. According to IR spectra, each of the MPAFA molecule coordinated to the metal centres via the azomethine nitrogen and the pyrazolyl tertiary nitrogen atoms. Single crystal X-ray diffraction studies of I and II had established a N6 donor set with a distorted octahedral structure for both the cases. Both the complexes exhibited some non-covalent interactions, like π…π stacking, H-bonding contacts etc. L, I and II had also been found to possess fluorescence property. Anticancer activities of L, I and II had been investigated and it was found that both the complexes I and II were stronger cytotoxic agents against the breast cancer cell line MCF7 than the primary ligand system; while all of them (L, I and II) were less toxic against a non-cancerous cell line HEK293. All the compounds had shown potential photocatalytic activity in degrading methylene-blue (MB).Peer reviewe

Synthesis, characterization and antimicrobial activity of some nickel, cadmium and mercury complexes of 5-methyl-3yl-N-(2′-methylthiophenyl)-methyleneimine, (MPzOATA) ligand

S.M. is thankful to the U.G.C., Govt. of India for providing financial support in the form of fellowship (videUGC Award No.: File No. 17-81/2008 (SA-I) dated: 04.1.2011). The financial support received from the University of Kalyani in the form of Personal Research Grant is thankfully acknowledged.Abstract Herein, we report the syntheses and structures of Ni(II) complexes, [Ni(MPzOATA)2] (Cl) (PF6) ( I ), [Ni(MPzOATA)2](ClO4)2.CH3CN (II) & [Ni(MPzOATA)2](BF4)2.H2O ( III ); Cd(II) complex, [Cd(MPzOATA)Cl2]2 ( IV ) and a Hg(II) complex, [Hg(MPzOATA)Cl2] ( V ), of a pyrazole based ‘NNS’ donor ligand, 5-methylpyrazole-3yl-N-(2′-methylthiophenyl)methyleneimine, (MPzOATA). The complexes are characterized byelemental analyses,electronic, IR, 1H NMR (only for IV & V ) spectral parameters, conductivity and fluorescence measurements. X-ray crystallographic data of the complexes reveal that the Ni(II) complexes have NiN4S2 octahedral coordination, one of them is a mixed-anion complex having Cl− and PF6− as counter anions; the Cd(II) complex is a chloro bridged binuclear complex with octahedral coordinationenvironment aroundeach metal centre, while the Hg(II) complex is a square pyramidal one. Among the reported complex species, the Ni(II) complexes are non-fluorescent, while the Cd(II) and Hg(II) complexes can be used as potential photoactive materials as indicated from their characteristicemission properties. The reported complexes are screened for their antimicrobial activities against some Gram positive and Gram negative microbial strains, and they are found to be potential antimicrobial agents in broad spectrum against both Gram positive and Gram negative bacteria.PostprintPeer reviewe

Synthesis, characterization and antimicrobial activities of Co(III) and Ni(II) complexes with 5-methyl-3-formylpyrazole-N(4)-dihexylthiosemicarbazone (HMPzNHex2) : X-ray crystallography and DFT calculations of [Co(MPzNHex2)2]ClO4·1.5H2O (I) and [Ni(HMPzNHex2)2]Cl2·2H2O (II)

Manan Saha is thankful to the U.G.C., Govt. of India for providing financial support in the form of Rajiv Gandhi National Fellowship (Number and date of award letter: F1-17.1/2013-14/RGNF-2013-14-SC-WES- 51398/(SA-III/Website); 06/02/2014). N.C. Saha is thankful to the University of Kalyani for financial assistance received in the form of Personal Research Grant.A new pyrazole containing ligand, 5-methyl-3-formylpyrazole-N(4)-dihexylthiosemicarbazone (HMPzNHex2), and a host of its cobalt(III) and nickel(II) complexes, [Co(MPzNHex2)2]X·mH2O and [Ni(HMPzNHex2)2]X2·nH2O (X= Cl, Br, ClO4, BF4 and NO3; m = 0 for Cl, Br, BF4 & NO3 and 1.5 for ClO4; n = 0 for Br, ClO4, BF4 & NO3 and 2 for Cl), respectively, have been synthesized and characterized by elemental analyses, magnetic measurements (polycrystalline state), 1H NMR (for the ligand and its Co(III) complexes), electronic and IR spectral parameters. All the reported Co(III) and Ni(II) complexes are cationic in nature and behaving as 1:1 and 1:2 electrolytes, respectively, in MeOH. Electronic spectral data of the complexes categorize them as havingdistorted octahedral coordination geometry. IR spectral features (4000-/450 cm-1) specify a monodeprotonated / neutral tridentate (NNS) function of the ligand, HMPzNHex2 coordinating to the Co(III) / Ni(II) via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato / thioketo sulfur atom. 1H NMR spectral data (in CDCl3 at 400 MHz) for the primary ligand and those of its Co(III) complexes are in agreement with the proposition of bonding sites evidenced from IR data. The single crystal x-ray data of I (C2/c (#15); monoclinic) and II (P-1 (#2); triclinic) have confirmed a CoN4S2 and a NiN4S2 octahedral coordination, respectively. The pair of monoprotic / neutral coordinating ligands is more or less orthogonal to each other in the complex species. The data obtained from DFT calculations are reasonably in agreement with the UV-Vis spectral assignment and the structures of the complex species. Although the ligand and the tested metal ion complexes are capable of inhibiting microbial growth, the cobalt complexes can be promoted as better antimicrobial agents.PostprintPeer reviewe

Synthesis and characterization of two Cu(II) complexes with a new pyrazole-based Schiff base ligand: crystallography, DNA interaction and antimicrobial activity of Ni(II) and Cu(II) complexes

<p>Reaction of Cu(II) nitrate with a new pyrazole-based Schiff base ligand, 5-methyl-3-formylpyrazole-N-(2′-methylphenoxy)methyleneimine (MPzOA), afforded two types of Cu(II) complexes at different reaction temperatures, [Cu(MP_zOA)(NO₃)]₂ (<b>1</b>) and [Cu(3,7,11,15-tetramethylporphyrin)(H₂O)](NO₃)₂ (<b>2</b>), reported together with a Ni(II) complex, [Ni(MPzOA)₂(H₂O)₂]Br₂ (<b>3</b>). The compounds are characterized by single crystal X-ray structure analyses along with several physico-chemical and spectral parameters. Complex <b>1</b> is authenticated as a bis(μ-pyrazolato)dicopper(II), while <b>2</b> is a porphyrinogen and <b>3</b> is a distorted octahedral complex. Structural analyses of the complexes reveal that <b>1</b> crystallized in monoclinic <i>P2</i>_<i>1</i><i>/n</i> space group while <b>2</b> and <b>3</b> crystallized in monoclinic <i>C2/c</i> space group. DNA-binding studies of the complexes have shown that the complexes interact with CT-DNA. DNA-cleavage studies with plasmid DNA have shown that <b>1</b> and <b>2</b> induce extensive DNA cleavage in the presence of H₂O₂ as an additive, whereas there is no change in degradation of super-coiled DNA by <b>3</b> in the presence of additive. The antimicrobial studies of the complexes against <i>Escherichia coli</i> DH5α bacteria strain indicated that all the complexes were capable of killing <i>E. coli</i> with different LD50 values.</p

Synthesis, characterization, X-ray crystallography and antimicrobial activities of new Co(III) and Cu(II) complexes with a pyrazole based Schiff base ligand

A new pyrazole based 'NNS' tridentate ligand, 5-methylpyrazole-3yl-N-(2'-methylthiophenyl)methyleneimine (MPzOATA), has been synthesized and characterized by elemental analyses, mass, IR and NMR spectroscopy. The versatile coordination mode of the ligand has been established with the synthesis of two metal-organic complexes with different metal ions, Co(III) (complex I) and Cu(II) (complex II). These metal-organic complexes have been characterized by single crystal X-ray structure analyses, along with several spectral techniques. Structural analyses of both the monomeric complexes reveal that complex I crystallized in the monoclinic C2/c space group, while complex II crystallized in the orthorhombic Pbca (#61) space group. In complex I, the Co(III) centre shows a six coordinate octahedral geometry, while in complex II, the Cu(II) centre shows a five coordinate square pyramidal geometry. The reported ligand and the metal ion complexes have been screened for their in vitro antimicrobial activity against some pathogenic bacteria. (C) 2013 Elsevier Ltd. All rights reserved.</p

Catalytic and anticancer activity of two new Ni(II) complexes with a pyrazole based heterocyclic Schiff-base ligand:synthesis, spectroscopy and x-ray crystallography

A new pyrazole containing ‘NN’ bidentate Schiff-base ligand, N-(furan-2-ylmethyl)-1-(5-methyl-1H-pyrazol-3-yl)methanimine, (MPAFA) (compound I) and its two new Ni(II) complexes, [Ni(MPAFA)2(H2O)2].2Cl.2H2O (compound II) and [Ni(MPAFA)3].2ClO4 (compound III) have been synthesized and characterized by various physico-chemical and spectral parameters viz., elemental analyses, mass, IR, NMR (1H and 13C, ligand only), UV-Vis spectral parameters and X-ray crystallographic studies. Both the complexes are behaving as 1:2 electrolytic species and the primary ligand, MPAFA, acts as a neutral ‘NN’ bidentate one in both the complexes. IR spectral data revealed that the coordination to each of the metal centre in both II and III, takes place through the pyrazolyl (tertiary) ring nitrogen and the azomethine nitrogen atom. X-ray data have revealed that both II and III are octahedral in nature and confirmed a NiN4O2 and NiN6 octahedral coordination, respectively. Ni(II) ion has formed two sets of complexes; in II, two molecules of ligand and two water molecules are coordinated to the metal forming a mixed ligand complex (1:2 complex), while in III, three ligand molecules are coordinated to the metal (1:3 complex). The ligand and the Ni(II) complexes reported here have been tested for their catalytic and anticancer activities. II and III have been found to be efficient in reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in presence of sodium borohydride (NaBH4) as a reducing agent; and are more potent cytotoxic agents and stronger anti-cancer materials against the breast cancer cell lines MCF7 and MDA-MB-231 than the primary ligand system