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.

Keywords:

• 3D Cd(II) coordination polymer
• carboxylate and pyridyl-hydrazone bridging
• Schottky barrier diode
• electrical conductivity
• light irradiation

Supplementary Material

Supplementary material for this work is available free of charge. It contains the materials, experimental section for the synthesis of 1 along with details about the Hirshfeld Surface analysis, DFT computations, FT-IR (Figure S1), H bonding and π···π interaction (Figure S2), Crystal packing (Figure S3) TGA (Figure S4), PXRD measurement (Figure S5), FESEM Image (Figure S6), EDX Spectrum and Mapping plot (Figure S7 and S8), Hirsfeld shape index (Figure S9), UV-Vis and Fluorescence spectra of pcih (Figure S10), UV-Vis and Fluorescence spectra of succ^2- (Figure S11); Crystallographic bond parameters (Table S1), List of H bonding and π···π interaction(Table S2), DFT computed structural data (Table S3).

Acknowledgments

The authors are thankful to Jadavpur University, India for its infrastructure.

Disclosure statement

No potential conflict of interest was reported by the authors.