A new trinuclear Cd(II)-based coordination polymer with Salen ligand building blocks: Synthesis, crystallographic aspects, and optimistic photosensitive Schottky barrier diode behaviour

Abstract

A new X-ray-characterized Cd(II)-based coordination polymer has been synthesized using Salen ligand (H2L1) and dicyanamide ion (dca) [N(CN)2]−, and characterized using elemental analysis, spectroscopy, SEM/EDX, TEM, and powder X-ray diffraction techniques. According to SCXRD, the complex crystallizes in the triclinic space group P-1. The asymmetric unit includes de-protonated ligands [L]2−, Cd(II) centres, and dca ions. The complex binuclear parts are connected by two μ1,5-dca bridges, resulting in the creation of a one-dimensional coordination polymer [(L1Cd)2(μ1,5-dca)2Cd]n. The polymer undergoes supramolecular aggregation via hydrogen bonding, CH···π(dca), and CH···π(arene) interactions. Hirshfeld surfaces (HS) and 2D fingerprint plots have been deployed to visualize the supramolecular interactions. The analysis shows that N…H interactions (18.2%) are more common in the crystal packing than Cd···O/O···H. This complex displays electrical conductivity and photosensitivity properties, making it a promising material for optoelectronic applications. Experimental and DFT studies have confirmed that it is a direct semiconductor with a specific optical band gap (3.54 eV) and is also used to construct a photosensitive Schottky barrier diode (SBD). The DFT calculated optical conductivity was used to analyse how the material's conductivity changes upon illumination. Due to the photon absorption, the material's electrical conductivity and photoconductivity change were concomitantly observed. Finally, the DOS analysis explains the complex's conductivity behaviour in a better logistic way.