A cadmium-thiocyanate coordination polymer with bridging 2-aminopyridine: Synthesis, characterization DFT studies, Hirshfeld Surface analysis and docking studies

Abstract

A one-dimensional [Cd(SCN)2]n coordination polymer doubly bridged by 2-aminopyridine has been synthesized via slow evaporation method at low temperature and it was characterized by single-crystal X-ray diffraction, Fourier Transform Infrared (FT-IR) spectroscopy, electronic spectroscopy, thermogravimetric analysis (TGA), and elemental analysis. The polymeric complex crystallizes in the triclinic crystal system with space group P-1. An analysis of the crystal structure as well as Hirshfeld surfaces (HS) associated with 2D fingerprint plots, indicates the existence of C–H· · · π and π-stacking interactions alongside NH—N and NH—S H-bonding interactions contributing to the stabilization of the layered assembly of the compound. Theoretical Density Functional Theory (DFT) Calculations (using different levels of theory) were done on the asymmetric unit of the polymer and a polymer fragment that reflects the coordination environment of Cd2+ in the polymer, to gain more information about the coordination environment of Cd2+ in the polymer. This also permitted a quantification of the interaction energies associated with hydrogen bonding and non-covalent interactions, as well as other quantum chemical parameters. Good consistency was found between the calculated results and the experimental structure. All the levels of theory used predict that the polymer fragment was less stable compared to the asymmetric unit except at the B3LYP/SSD level of theory. Analysis of the HOMO and LUMO was used to explain the charge transfer within the polymer. Thermal analysis of the polymer indicates it decomposes in two steps resulting in a residue indexed to the hexagonal phase of CdS JCPDS [06–0314]. The activity of the metal complex against breast, lung, and liver cancer was measured. The interactions occurring in the docking calculation were examined in detail with PLIP (Protein-Ligand Interaction Profiler) analysis. Lastly, Swiss- ADME (absorption, distribution, metabolism and excretion) analysis was performed to examine the pharmacological properties of the metal complex.