Direct synthesis of a stable radical doped electrically conductive coordination polymer

Abstract

Radical coordination polymers exhibit tremendous potential in many areas. However, stable radical ligands are still rare and the syntheses of radical ligand derived coordination polymers are mainly limited to liquid diffusion based methods. Therefore, further exploration of new types of stable radical coordination polymers is strongly desired. Herein, we report on an NDI-based coordination polymer, [K₂(ONDI)]_∞ (K-ONDI), which is synthesized directly by solvothermal reaction and exhibits radical properties and high stability in air as well as in common organic solvents. The NDI˙⁻ radicals in K-ONDI are supposed to originate from electron transfer to the ONDI²⁻ ligand under solvothermal conditions. Furthermore, benefitting from continuous π-stacking of the ligand in the crystal structure and unpaired electrons from NDI˙⁻, K-ONDI shows intriguing semiconductive behaviour with an electrical conductivity value of 10⁻⁶ S cm⁻¹.