Thahira Begum S. A. Ravoof

Synthesis, characterization and biological evaluation of transition metal complexes derived from N, S bidentate ligands.

Two bidentate NS ligands were synthesized by the condensation reaction of S-2-methylbenzyldithiocarbazate (S2MBDTC) with 2-methoxybenzaldehyde (2MB) and 3-methoxybenzaldehyde (3MB). The ligands were reacted separately with acetates of Cu(II), Ni(II) and Zn(II) yielding 1:2 (metal:ligand) complexes. The metal complexes formed were expected to have a general formula of [M(NS)2] where M = Cu2+, Ni2+, and Zn2+. These compounds were characterized by elemental analysis, molar conductivity, magnetic susceptibility and various spectroscopic techniques. The magnetic susceptibility measurements and spectral results supported the predicted coordination geometry in which the Schiff bases behaved as bidentate NS donor ligands coordinating via the azomethine nitrogen and thiolate sulfur. The molecular structures of the isomeric S2M2MBH (1) and S2M3MBH (2) were established by X-ray crystallography to have very similar l-shaped structures. The Schiff bases and their metal complexes were evaluated for their biological activities against estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) breast cancer cell lines. Only the Cu(II) complexes showed marked cytotoxicity against the cancer cell lines. Both Schiff bases and other metal complexes were found to be inactive. In concordance with the cytotoxicity studies, the DNA binding studies indicated that Cu(II) complexes have a strong DNA binding affinity.

New insight into the structural, electrochemical and biological aspects of macroacyclic Cu(II) complexes derived from S-substituted dithiocarbazate schiff bases

Copper (II) complexes synthesized from the products of condensation of S-methyl- and S-benzyldithiocarbazate with 2,5-hexanedione (SMHDH2 and SBHDH2 respectively) have been characterized using various physicochemical (elemental analysis, molar conductivity, magnetic susceptibility) and spectroscopic (infrared, electronic) methods. The structures of SMHDH2, its copper (II) complex, CuSMHD, and the related CuSBHD complex as well as a pyrrole byproduct, SBPY, have been determined by single crystal X-ray diffraction. In order to provide more insight into the behaviour of the complexes in solution, electron paramagnetic resonance (EPR) and electrochemical experiments were performed. Antibacterial activity and cytotoxicity were evaluated. The compounds, dissolved in 0.5% and 5% DMSO, showed a wide range of antibacterial activity against 10 strains of Gram-positive and Gram-negative bacteria. Investigations of the effects of efflux pumps and membrane penetration on antibacterial activity are reported herein. Antiproliferation activity was observed to be enhanced by complexation with copper. Preliminary screening showed Cu complexes are strongly active against human breast adenocarcinoma cancer cell lines MDA-MB-231 and MCF-7.

Synthesis and characterization of mixed-ligand copper(II) saccharinate complexes containing tridentate NNS Schiff bases. X-ray crystallographic analysis of the free ligands and one complex

Abstract Four new Schiff bases containing N and S heteroatoms (HL1–HL4) have been prepared and characterized, including determination of the X-ray crystal structures of HL1 and HL3. Spectroscopic evidence indicates that these Schiff bases behave as uninegatively charged tridentate NNS ligands in complexes of general formula [Cu(Ln)sac] (Ln is the anionic form of NNS, and sac represents saccharinate anion). Crystals of both HL1 and [Cu(L4)sac)(H2O)]·Hsac crystallized in triclinic system with P

2-[(1E)-({[(Benzyl-sulfan-yl)methane-thio-yl]amino}-imino)-meth-yl]-6-meth-oxy-phenol: crystal structure and Hirshfeld surface analysis.

\bar{1}

{S-Benzyl 3-[(6-methyl-pyridin-2-yl)-methyl-idene]dithio-carbazato}nickel(II) monohydrate.

1¯ space group, while HL3 crystallized in monoclinic system with P 21/c space group. [Cu(L4)sac)(H2O)]·Hsac has a distorted square-pyramidal structure with a non-bonded saccharin molecule present in the outer coordination sphere. The tridentate NNS ligands are coordinated to Cu through pyridine nitrogen, azomethine nitrogen and thiolate sulfur atoms, while the fourth and fifth coordination positions are occupied by the N-bonded saccharinate anion and a water ligand, respectively.

N′-[Bis(benzyl­sulfan­yl)methyl­idene]benzohydrazide

The title compound C8H15N3S has two molecules in the asymmetric unit in which cis–trans isomerism is exhibited around the N(NH)C=S bonds. The cyclohexyl rings in both molecules adopt a chair conformation. In the crystal, N—H⋯S hydrogen bonding produces dimers, which are interconnected through further N—H⋯S hydrogen bonds, forming chains along the b-axis direction.

Bis(N′-{(E)-[(2E)-1,3-di­phenyl­prop-2-en-1-yl­idene]amino}-N-ethyl­carbamimido­thio­ato-κ2N′,S)zinc(II): crystal structure and Hirshfeld surface analysis

Two almost planar residues in the title thione are orientated perpendicularly [dihedral angle = 82.72 (5)°]; the conformation about the imine bond is E. In the crystal, centrosymmetric aggregates are formed via {⋯HNCS}2 synthons which are linked into supramolecular layers by C—H⋯O interactions.

A cinnamaldehyde Schiff base ofS-(4-methylbenzyl) dithiocarbazate: crystal structure, Hirshfeld surface analysis and computational study

In the title compound, C16H15N3S2, the central C2N2S2 residue is planar (r.m.s. deviation = 0.045 Å) and the pyridyl and benzene rings are inclined and approximately coplanar to this plane, respectively [dihedral angles = 72.85 (9) and 10.73 (9)°], so that, overall, the molecule adopts an L-shape. The conformation about each of the N=C [1.290 (3) Å] and C=C [1.340 (3) Å] bonds is E. Supramolecular chains along [1-10] are stabilized by N—H⋯N(pyridine) hydrogen bonding and these are connected into a double layer that stacks along the c-axis direction by C—H⋯π(pyridine) interactions.