We consider an interacting one-dimensional molecular wire attached to two metal electrodes on either side of it. The electrostatic potential profile across the wire-electrode interface has been deduced solving the Schrodinger and Poisson equations self-consistently. Since the Poisson distribution crucially depends on charge densities, we have considered different Hamiltonian parameters to model the nano-scale wire. We find that for very weak electron correlations, the potential gradient is almost zero in the middle of the wire but are large near the chain ends. However, for strong correlations, the potential is essentially a ramp function. The nonlinear current, obtained from the scattering formalism, is found to be less with the ramp potential than for weak correlations. Some of the interesting features in current-voltage characteristics have been explained using one-electron formalism and instabilities in the system.

A hydrothermal reaction of a mixture of ZnCl₂, V₂O₅, ethylenediamine and water gave rise to a layered poly oxovanadate material [Zn₂(NH₂(CH₂)₂NH₂)₅][{Zn(NH₂(CH₂)₂NH₂)₂}₅{V₁₈O₄₂(H₂O)}].xH₂O (x ∼ 12) (I) consisting of [V₁₈O₄₂]¹²⁻ clusters. These clusters, with all the vanadium ions in the +4 state, are connected together through Zn(NH₂(CH₂)₂NH₂)₂ linkers forming a two-dimensional structure. The layers are also separated by distorted trigonal bipyramidal [Zn₂(NH₂(CH₂)₂NH₂)₅] comple_xes. The structure, thus, presents a dual role for the Zn-ethyl-enediamine comple_x. The magnetic susceptibility studies indicate that the interactions between the V centres inI are predominantly antiferromagnetic in nature and the compound shows highly frustrated behaviour. The magnetic properties are compared to the theoretical calculations based on the Heisenberg model, in addition to correlating to the structure. Crystal data for the comple_xes are presented.

An experimental charge density study has been carried out on proton-transfer complexes exhibiting nonlinear optical (NLO) properties-melaminium tartrate monohydrate and L-asparaginium picrate employing high-resolution X-ray diffraction at 100 K. Both the complexes crystallize in non-centric space group P2₁ and the structures exhibit interesting patterns of N-H…O and O-H…O hydrogen bonding. Experimental determination of the dipole moment (𝜇) for the asymmetric unit reveals that for both the crystals, there is a large cooperative enhancement in the crystalline 𝜇 arising essentially due to hydrogen bond mediated charge transfer between the melaminium ion and the L-tartrate in one case, between the Lasparaginium ion and the picrate in the other complex. We have additionally performed theoretical calculations at the density functional theory (DFT) level to understand the origin of enhancement of the dipole moments in the two systems.

We have modelled for the first time a chemodosimeter for As(III) detection in water. The chemodosimeter modelled is a 1,3-dithiole-2-thione derivative with an anthracene unit which has been previously described as a chemodosimeter for Hg(II) detection. Quantum chemical calculations at the DFT level have been used to describe the binding energies and selectivity of the chemodosimeter. We find that the dosimeter action is intrinsically dependent on the thiophillic affinity and the coordination sphere of the metal ion. Binding studies for a series of metal ions: Pb(II), Cd(II), Hg(II), Ni(II) and As(III) followed by an analysis of the complete reaction pathway explains the high selectivity of the dosimeter towards As(III). The dosimeter efficiency is calculated as 66% for As(III)-ion.

We have investigated the structural aspects of several carbon dioxide molecular aggregates and their spectroscopic and nonlinear optical properties within the quantum chemical theory framework. We find that, although the single carbon dioxide molecule prefers to be in a linear geometry, the puckering of angles occur in oligomers because of the intermolecular interactions. The resulting dipole moments reflect in the electronic excitation spectra of the molecular assemblies. The observation of significant nonlinear optical properties suggests the potential application of the dense carbon dioxide phases in opto-electronic devices.