Highly luminescent oligo(phenylenevinylene) films: the stereochemical approach

Unsubstituted OPV's are bright fluorophores in solution but poor ones in fi lms, due to unfavorable side-by-side inter-molecular arrangement. To overco me this morphology, the complete isomeric series of di- and tetracyano trim eric PV's and (RO)(2)PV's are synthesized and investigated as films with ti me-resolved polarized fluorescence spectroscopy. Depending on intermolecula r arrangement and intramolecular torsional degrees of freedom, the fluoresc ence yields in the films range from 0.01 to 0.8. Highest values are obtaine d with head-to-tail intermolecular arrangement. Depending on the substituti on pattern, excimer or monomer like fluorescence dominates.