Syntheses, structural diversity and properties of three coordination polymers built by chlorophenyl imidazole dicarboxylate

Effective Approach to Promoting the Proton Conductivity of Metal-Organic Frameworks by Exposure to Aqua-Ammonia Vapor

We explored the proton conductivities of two 3D Co^II metal-organic frameworks (MOFs), {[Co₃(m-ClPhIDC)₂(H₂O)₆]·2H₂O}_n [1; m-ClPhH₃IDC = 2-(m-chlorophenyl)imidazole-4,5-dicarboxylic acid] and {[Co₃(p-ClPhHIDC)₃(H₂O)₃]·6H₂O}_n (2; p-ClPhH₃IDC = 2-(p-chlorophenyl)imidazole-4,5-dicarboxylic acid), under water and aqua-ammonia vapors, respectively. The experimental results revealed that the proton conductivities of 1 and 2 at aqua-ammonia vapor were 2.89 × 10^-2 and 4.25 × 10^-2 S/cm, respectively, and approximately 2 orders of magnitude greater than those at water vapor. On the basis of the activation energy, water and ammonia vapor absorption, and powder X-ray diffraction patterns, their proton-conduction mechanisms have been discussed. We believe that this is a novel approach to drastically improving the proton conductivity of MOFs.