Proton conduction and impedance sensing of a highly stable copper–organic framework from imidazole dicarboxylate

Abstract

We have successfully synthesized a novel one-dimensional MOF, [Cu4(HDMPhIDC)4(H2O)4]n (1) by solvothermal method with the ligand 2-(3,4-dimethyl)phenyl-4,5-imidazole dicarboxylic acid (H3DMPhIDC). After analyzing its crystal structure, we have verified water stability, acid-base stability and adsorption properties of 1. We have measured the proton conductivity of 1 under water vapor and found the proton conductivity of 1 being 2.58 × 10−5 S·cm−1 at 98% relative humidity (RH) and 100 °C. Interestingly, MOF 1 shows good ammonia identification. The minimum ammonia sensing concentration is 10 ppm to be recognized by 1 at 25 °C. The lower the RH is, the more apparent the identification for ammonia is. When RH is 85% and the ammonia concentration in the system increases from 0 to 60 ppm, the impedance value of 1 is reduced from 4.29 × 108 to 1.07 × 106 Ω with high response of 39993%.