Structure and Extended Electronic States in Molecular Assemblies of Hemicyanine Amphiphiles

Abstract

Hemicyanine dyes containing long alkyl chains have attracted considerable attention in recent years due to their significance as possible optoelectronic and molecular electronic materials. With large non-linear molecular polarizabilities, amphiphilic hemicyanines are readily incorporated into Langmuir-Bludgett monolayer and multilayer films, forming artificial molecular assemblies with preferred spatial and orientational order [1,2], In contrast to centrosymmetric bulk materials, in which the individual effects are canceled, and the overall bulk second-order susceptibility vanishes [1], highly aligned structures ensure non-zero macroscopic second-order susceptibilities, χ(2). In addition molecular assemblies of these materials have been shown to be characterized by extended electronic states in which the relationship between molecular structure and delocalization of the electronic states is a matter of current interest.