Raman and site-selective fluorescence spectra of model compounds for interchain interactions in poly(phenylenevinylene)

Nonresonant Raman spectra and site-selective fluorescence spectra (polyethylene matrix, 1.5 K) are reported for 1,4-distyrylbenzene, its tert-butyl and paracyclophane substituted derivatives, and the paracyclophane derivative bearing two distyrylbenzene chains in a pseudo-para orientation, a simple model for the interchain interactions in poly(phenylene-vinylene) films. The first three compounds show pronounced fluorescence line-narrowing when excited near the red edge of their absorption spectra. The bichromophoric compound exhibits no narrowing although its Raman spectrum, room-temperature fluorescence spectrum, and lifetime are similar to those of the other three molecules. This may reflect increased low-frequency Franck–Condon activity in the electronically delocalized bichromophoric system.