Two proton-conductive hybrids based on 2,2′-biimidazole molecules and Keggin-type heteropolyacids

• Published in: Journal of solid state chemistry Vol. 198; pp. 323 - 329
• Main Authors: Wei, Mei-Lin, Wang, Jun-Hua, Wang, Yu-Xia
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.02.2013; Elsevier
• Subjects: 2,2′-Biimidazole; Condensed matter: structure, mechanical and thermal properties; Conducting materials; Cross-disciplinary physics: materials science; rheology; Diffusion in solids; Exact sciences and technology; Materials science; Organic compounds; Organic–inorganic complexes; Other materials; Physics; Polyoxometalates; Specific materials; Structure elucidation; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Theory of diffusion and ionic conduction in solids; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids; Transport properties of condensed matter (nonelectronic); Polyoxometalates; Organic–inorganic complexes; Structure elucidation; Conducting materials; 2,2′-Biimidazole; Ionic conduction; Metallates; Organometallic compounds; Thermogravimetry; XRD; Lattice parameters; Molybdenum; Thermal stability; Thermal properties; Triclinic lattices; Experimental result; Hydrogen bonds; 2,2'-Biimidazole; Supramolecular structure; Humidity; Proton conductivity; X-ray diffraction analysis; Organic-inorganic complexes
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2012.10.025

Two proton-conductive organic/inorganic complexes were constructed by Keggin-type heteropolyacids and 2,2′-biimidazole molecules. Single-crystal X-ray diffraction analyses revealed that two complexes crystallized in the triclinic space group Pī, exhibited very close unit cell parameters, and presented similar three-dimensional (3D) hydrogen-bonded networks constructed by H2biim, [PM12O40]3− (M=W for 1 and Mo for 2) and solvent molecules. The results of thermogravimetric analyses (TG) suggest that two supramolecular complexes have similar thermal stability based on the same 3D packing. Two complexes at 100°C under 98% relative humidity showed a good proton conductivity of about 10−4Scm−1. A possible mechanism of the proton conduction was proposed according to the experimental results. Two molecular hybrids constructed by Keggin-type heteropolyacids and 2,2′-biimidazole molecules showed good proton conductivities of 10−4Scm−1 in the temperature range of 85–100°C under 98% relative humidity. [Display omitted] ► H2biim shows the ability to form hydrogen bonds via the N-H groups in the context of crystal engineering. ► Heteropolyacids have suitable characteristics to be used excellent proton conductors. ► Two new supramolecular complexes based-on Keggin-type heteropolyacids and H2biim molecules were constructed. ► The structure was determined by using single-crystal X-ray diffraction data. ► Both complexes showed good proton conductivities of 10−4Scm−1 in the temperature range of 85–100°C.