Ionic conductivity on cyano-bridged bimetal assemblies

European Chemistry Congress

June 16-18, 2016 Rome, Italy

Kosuke Nakagawa, Kenta Imoto and Shin-ichi Ohkoshi

The University of Tokyo, Japan

Posters & Accepted Abstracts: Chem Sci J

Abstract :

Various interesting functionalities have been reported on Prussian blue analogues, such as humidity sensitive magnetism. Prussian blue analogues have two types of cubic crystal structures. One of them is MAII[MBIII(CN)6]2/3â�?¢zH2O type (MA, MB: transition metal ions). There are vacancies of [MB(CN)6] in MA[MB(CN)6]2/3â�?¢zH2O, and water molecules are coordinated to MA ions and/or exist in the vacancy sites. Herein we report high ionic conductivities (Ï�?) of 1.2�?�?10â�?�?3 S cmâ�?�?1 for Co[Cr(CN)6]2/3â�?¢zH2O (1) and 1.6�?�?10â�?�?3 S cmâ�?�?1 for V[Cr(CN)6]2/3â�?¢zH2O (2) at 293 K, 100%RH, respectively. As the humidity decreased, Ï�? of 1 drastically decreased to 3.2�?�?10â�?�?8 S cmâ�?�?1 at 8%RH. This result indicates that the origin of ionic conduction is explained by Grotthuss mechanism, i.e., proton transfer is mediated by hydrogen-bonding network of water molecules. Ï�? at 100%RH of 1 and 2 increased as temperature was increased. The plot of ln(Ï�?T) vs Tâ�?�?1 of 1 was linear and gave an activation energy (Ea) of 0.22 eV, whereas, the slope of the plot of 2 changed at an intermediate temperature. The Ea values in the high- and low-temperature regions were 0.10 and 0.19 eV, respectively. The folding point of 313 K corresponds to the magnetic transition temperature of 2, which indicates that an interference effect between magnetic ordering and proton conduction was observed.

Biography :

K. Nakagawa has completed his PhD at the age of 27 years from The University of Tokyo. He studies as a postdoctoral researcher at The University of Tokyo, School of Science.
Email:knaka@chem.s.u-tokyo.ac.jp