Molecular packing in unsubstituted semiconducting phenylenevinylene oligomer and polymer

p-Bis(p-styrylstyryl)benzene, C38H30, a five-ring phenylene-vinylene model compound for unsubstituted PPV, has been obtained in single-crystal form an d the crystal structure has been resolved. The arrangement of the molecules is of the herringbone-type, and its characteristic dimensions correspond r emarkably well to those of the structure proposed for PPV in 1986, This pac king mode is entirely different from what has been found for substituted ol igo(phenylenevinylene)s but similar to that observed in other types of conj ugated oligomers without lateral substituents. Thin films of the unsubstitu ted oligomer show electroluminescence at a lower onset voltage and blue-shi fted relative to substituted oligo(phenylenevinylene)s.