The equilibrium statistical mechanics of cooperative intramolecular behavior in molecules with coupled conformational/electronic transitions

Abstract

Molecules, such as conjugated polymers, whose electronic structure is significantly altered by conformational changes can be shown to have cooperative conformational transitions. In an isolated polymer, this long ranged cooperativity can be analyzed by representing the polymer as a one-dimensional gas of simple conformational defects that interact with a nearest-neighbor attraction. For a condensed phase, it is suggested that the same analysis remains valid but that the relevant defects become more complex. The resulting ‘‘thermodynamics’’ of the defects, along with their predicted spatial distribution, have experimental consequences for the UV/visible and Raman spectra of conjugated polymers— some aspects of which are discussed.