Vedapriya Pandarinathan

Synthesis, crystal structure description, electrochemical and DNA binding studies of ‘paddlewheel’ copper(II) carboxylate

Dimeric paddlewheel copper(II) complex, pyCu(phenylacetate)4Cupy, where py = pyridine, has been prepared and the crystal structure determined. Single crystal X-ray diffraction (XRD) revealed three crystallographically independent molecules in the unit cell. The geometry around each Cu(II) is square pyramidal with monodentate pyridine at the apical and bidentate carboxylates in the equatorial positions. The supramolecular structure of the complex arises primarily as a result of C–H⋯O along with some contribution of C–H⋯C interactions, resulting in the preferential alignment of the molecules along the c-axis. The purity of the crystalline complex has been confirmed through powder XRD study. Electrochemical solution study of the complex in aqueous DMSO (1 : 4) showed two redox couples corresponding to Cu(III)/Cu(II) and Cu(II)/Cu(I) irreversible electron transfer. The values of various voltammetric variables, such as diffusion coefficient (Do), heterogeneous rate constant (k°), formal potential (E°), and charge transfer coefficient (α), have been calculated before and after DNA addition. DNA binding of the complex has been explored through cyclic voltammetry, UV–visible spectrophotometry, and viscosity measurement which have exhibited a mixed electrostatic and intercalative mode of interaction. Cyclic voltammetry indicated self-induced redox activation and potential anticancer ability of the complex, supported by UV–visible spectrophotometry as well as viscometry. Graphical Abstract

Transformation of Cadmium Tetracyanoquinodimethane (TCNQ) into a Cadmium Terephthalate Metal-Organic Framework

The transformation of cadmium 7,7,8,8-tetracyanoquinodimethane (TCNQ) into a cadmium terephthalate co-ordination polymer is reported, with the chemistry of this material elucidated using elemental analysis, X-ray photoelectron spectroscopy and synchrotron radiation single-crystal X-ray diffraction. A heptacoordinated CdII linear coordination polymer catena-poly[triaqua-(μ2-benzene-1,4-dicarboxylato-κO,O′)cadmium(ii)]hydrate (1) was isolated while attempting to recrystallize Cd(TCNQ)2. Density functional theory calculations for the oxidation of benzylic carbon attached to the cyano group provided evidence that the reaction pathway proposed herein is highly exergonic and thermodynamically plausible. This structure showed a distorted pentagonal bipyramidal geometry together with a symmetrical mononuclear unit in which each CdII ion is doubly bridged by a dicarboxylato anion. Owing to the softness and minute size of these crystals, this structure had to be elucidated using synchrotron radiation X-ray crystallography.