Elucidating structure–property relationships in Cd(II) coordination polymers for charge transport and Schottky device fabrication

Abstract

Herein, we report the synthesis of two isostructural one-dimensional (1D) Cd(II) coordination polymers (CPs) based on monodentate [4-[2-(9-anthryl)vinyl] pyridine)] (4-avp) ligand, [Cd(DCTP)(4-avp)2(CH3OH)2] (CP1) and [Cd(DBTP)(4-avp)2(CH3OH)(H2O)] (CP2), using bidentate O-donor linker 2,5-dichloroterephthalic acid (H2DCTP) and 2,5-dibromoterephthalic acid (H2DBTP) respectively. The CP1 and CP2 have been synthesized and characterized by elemental analysis, Fourier-transform infrared (FTIR) spectroscopy and single crystal X-ray diffraction (SCXRD) technique. Structural analyses reveal that both the CP1 and CP2 create 1D chain polymer via bridging of ditopic linker H2DCTP/H2DBTP. Interestingly, both the CPs exhiit electrical conductivity and Schottky behavior. However, CP1 exhibits superior conductivity (7.55 × 10-4 Sm⁻¹) as compared to CP2 (3.78 × 10–4 Sm⁻¹). This difference in conductivity is rationalized by solid-state density functional theory (DFT) calculations, which reveal that the frontier orbitals (HOMO and LUMO) are exclusively localized on the conjugated 4-avp linkers. Consequently, the superior charge transport in CP1 is attributed to the parallel π⋯π stacking of these active 4-avp units, which provides a more efficient orbital overlap than the crossed arrangement observed in CP2. These results highlight the critical role of ligand arrangement in modulating the electronic properties of d10 metal-based CPs for electronic device fabrication.