Intermolecular forces in modification III of 1,4-Dithioketo-3,6-diphenyl-pyrrolo-[3,4-c]-pyrrole

Abstract

Due to an intense near-IR absorption, the title compound has recently attracted attention as a material suitable for laser printers and optical disks. The near-IR absorption, however, appears only in modification III characterized by the “bricks in a brick wal1” structure comprising three kinds of molecule-pairs: hydrogen-bond, convex and concave pairs. Intermolecular forces in modification III have been investigated by means of an energy partition analysis of the total energy on the basis of molecular orbital calculations. In the H-bond pair, the orbital overlap and the electrostatic interactions almost equally contribute to the stabilization of the total system. On the other hand, in convex and concave pairs, the intermolecular interactions are found to be purely of electrostatic nature. The present calculation gives us a rough picture how the “bricks in a brick wall” structure is formed in modification III.