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

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) (H(2)succ = succinic acid; pcih = pyridine-4-carboxaldehyde iso-nicotinoyl hydrazone). Compound 1 was structurally characterized by single-crystal X-ray diffraction. The bridging groups, succ(2-) and pcih, self-assembled via H-bonding and pi center dot center dot center dot pi 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 omega (dark); 133.73 omega (light), also support the photoinduced enhancement of conductivity. The non-ohmic relation, I alpha V-2, showed an enhancement of conductivity by 2.5 times upon light irradiation [3.36 x 10(-6) S m(-1) (dark) and 8.37 x 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.