Succinato-bridged Cd(II)-nicotinylhydrazone 3D coordination polymer: structure, photoconductivity and computational studies

Abstract

Strategies for clean energy are important components of the United Nation’s Sustainable Development Goals (SDGs). To this end, we have studied the conductivity of a Cd(II)-based 3D coordination polymer, [Cd(succ)(pcih)(H2O)]n (1) (H2succ = succinic acid; pcih = pyridine-4-carboxaldehyde iso-nicotinoyl hydrazone). Compound 1 was structurally characterized by single-crystal X-ray diffraction. The bridging groups, succ2 − and pcih, self-assembled via H-bonding and π∙∙∙π interactions. The optical band gap calculated from a Tauc’s plot was determined to be 3.71 eV which is consistent with semiconducting behavior. The experimental barrier height, 0.71 eV (dark phase); 0.49 eV (light phase) and series resistance, 358.48 Ω (dark); 133.73 Ω (light), also support the photoinduced enhancement of conductivity. The non-ohmic relation, I α V2, showed an enhancement of conductivity by 2.5 times upon light irradiation [3.36 × 10−6 S m−1 (dark) and 8.37 × 10−6 S m−1 (light)]. DFT computations employing the crystallographic parameters of 1 indicated a HOMO/LUMO energy gap of 4.06 eV, within the range of semiconducting materials. The optical stability of 1 was examined by fluorescence measurements and lifetime data.