Highly proton-conductive copper coordination polymer, H2dtoaCu (H2dtoa = dithiooxamide anion)

Room-temperature proton conductivity, coordination geometry, and pore-diameter distribution of the title Cu(II) coordination polymer have been investigated by AC conductivity, EXAFS, and N-2 adsorption isotherm measurements. The AC proton conductivity (sigma(p)) obtained from Cole-Cole plot analysis under relative humidity of 75% and 300 K exhibits a considerable high value of 10(-6) S cm(-1) as a room-temperature sigma(p). The mechanism of proton conduction seems to be similar to that of a proton-exchange membrane, Nahon, which contains much cluster of water molecules in the porous space of the polymer. The present Cu coordination polymer was revealed to possess porous space of about 6 Angstrom, which includes much water molecules more than 10H(2)O per unit cell. The dimeric Cu(II) square-planar coordination geometry was confirmed by EXAFS analysis using synchrotron radiation source at SPring-8. (C) 2002 Elsevier Science B.V. All rights reserved.