Guided self-assembly of unidirectionally oriented quasi-one-dimensional 3,4,9,10-perylene-tetracarboxylic-dianhydride chains using surface nanowires

A quasi-one-dimensional chains of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules are grown by using nanowire arrays on a In/Si(111)- ( 4 × 1 ) surface as a template. The PTCDA molecules self-assemble in a "head-and-tail" configuration with their long axis aligned with the direction of the surface nanowires. This unidirectional orientation is unique and indicates that the molecular arrangement is not governed by hydrogen bonding which prevails in the self-assembly of the PTCDA molecules on two-dimensional surfaces. Existence of weak and short-ranged interchain molecular interactions is also deduced, revealing the quasi-one-dimensional character of the molecular chains.