438 Recyclable Supramolecular Organic Conductors Tailored by Strong and Directional Iodine Bonds

Friday, November 6, 2009: 11:40 AM
Pancho Villa (Camino Real Hotel)
Tatsuro Imakubo , Department of Materials Science and Technology, Nagaoka University of Technology, Nagaoka, Japan
From a viewpoint of crystal design of organic conductors, we have focused our attention to the iodine-based intermolecular interaction, i.e. 'iodine bond'. The iodine bond is a special case of a so-called 'halogen bond' and its strength and directionality are outstanding among the halogen bonds. It is also noted that the iodine bond is suitable for applications to TTF-based organic conductors because of the lowest electronegativity of iodine among the halogen elements, which does not reduce donor ability of the TTF skeleton. In this paper, we report our recent results on development of recyclable supramolecular organic conductors using the iodine bond. We have prepared PF6 salts of pyrazine-fused iodinated p-donors diiodo(pyrazino)tetraselenafulvalene (DIPSe) and diiodo(pyrazino)tetrathiafulvalene (DIP) by galvanostatic oxidation. X-ray structure analysis revealed that all these salts are isostructural and crystallize in the hexagonal P63/mcm space group. There are strong and directional I···N iodine bonds among the donor molecules and two types of channels including the counter anion and the solvent of crystallization are tailored by the iodine bond. Room temperature conductivities of these hexagonal salts depend on the chalcogen species in the donor molecules and they are in the range of 10-100 Scm-1. In addition to the unique crystal structure and high electrical conductivity, high yield recovery of the neutral p-donor from the cation radical salts has been accomplished by a simple chemical reaction, i.e. a redox reaction between water and the cation radical salts.