Structure, electronic properties, and NBO and TD-DFT analyses of nickel(II), zinc(II), and palladium(II) complexes based on Schiff-base ligands

Supramolecular Arrangement and DFT analysis of Zinc(II) Schiff Bases: An Insight towards the Influence of Compartmental Ligands on Binding Interaction with Protein

We report, for the first time, a detailed crystallographic study of the supramolecular arrangement for a set of zinc(II) Schiff base complexes containing the ligand 2,6-bis((E)-((2-(dimethylamino)ethyl)imino)methyl)-4-R-phenol], where R=methyl/tert-butyl/chloro. The supramolecular study acts as a pre-screening tool for selecting the compartmental ligand R of the Schiff base for effective binding with a targeted protein, bovine serum albumin (BSA). The most stable hexagonal arrangement of the complex [Zn-Me] (R=Me) stabilises the ligand with the highest FMO energy gap (ΔE=4.22 eV) and lowest number of conformations during binding with BSA. In contrast, formation of unstable 3D columnar vertebra for [Zn-Cl] (R=Cl) tend to activate the system with lowest FMO gap (3.75 eV) with highest spontaneity factor in molecular docking. Molecular docking analyses reported in terms of 2D LigPlot+ identified site A, a cleft of domains IB, IIIA and IIIB, as the most probable protein binding site of BSA. Arg144, Glu424, Ser428, Ile455 and Lys114 form the most probable interactions irrespective of the type of compartmental ligands R of the Schiff base whereas Arg185, Glu519, His145, Ile522 act as the differentiating residues with ΔG=-7.3 kcal mol-1 .

Theoretical investigation on orange-emitting cyclometalated platinum (II) complexes containing organosilyl/organocarbon-substituted 2-(2-thienyl)pyridine ligands

This paper presents a theoretical investigation of structural, optical, and phosphorescence properties of four cyclometalated Pt(II) complexes containing substituted 2-(2-thienyl)pyridine ligands using DFT and TD-DFT methods. Geometrical parameters of ground states were calculated and compared with available experimental data. Electronic absorptions were studied and assigned in terms of natural transition orbitals. Phosphorescence spectra have been simulated with adiabatic Hessian and adiabatic shift approaches according to the Franck-Condon approximation. Theoretical and experimental results agree and show that the four complexes exhibit two intense bands in orange region. Main normal modes involved in phosphorescence bands were analyzed and assigned.