Influence of cations on charge transport and Schottky properties in mesaconate-bridged isostructural 1D coordination polymers

Abstract

Coordination polymers (CPs) are versatile materials with applications across various fields, including the development of supramolecular electronic devices aimed at harnessing renewable energy sources. In this study, we report the design and synthesis of two one-dimensional (1D) CPs: [Cd(4-avp)₂(mes)(H₂O)]·H₂O (CP1) and [Zn(4-avp)₂(mes)(H₂O)]·H₂O (CP2) constructed using a relatively underexplored, highly conjugated polycyclic aromatic hydrocarbon (PAH)-based monodentate ligand, 4-[2-(9-anthryl)vinyl]pyridine (4-avp), in combination with a linear bidentate linker, mesaconic acid (H₂mes). Both compounds were characterized through elemental analysis, Fourier-transform infrared (FTIR) spectroscopy, and single-crystal X-ray diffraction (SCXRD). Structurally, the Cd(II) or Zn(II) metal centers are bridged by mes ligands to form 1D polymeric chains. The axial sites are coordinated by 4-avp ligands, which engage in π⋯π interactions and promote the formation of higher-dimensional supramolecular networks combining with hydrogen bonding interactions. Remarkably, both CPs display semiconducting properties and function as Schottky barrier diodes. Notably, CP1 demonstrates significantly enhanced electrical conductivity (1.39 × 10⁻³ S m⁻¹), approximately four times higher than that of CP2 (3.71 × 10⁻⁴ S m⁻¹). This improved performance is attributed to the larger Cd(II) ion, which allows greater orbital overlap, thereby facilitating more efficient charge transport. These findings are further supported by band gap calculations using density functional theory (DFT) computation and density of state (DOS) calculations.