Single-crystal structures of model compounds for poly(2,5-dialkoxy-1,4-phenylenevinylene)

We report on the crystal structures of two alkoxy-substituted distyrylbenze ne derivatives 4 and 5 which serve as model compounds for poly(1,4-phenylen evinylene)s and compare them to other known compounds 6-9 of similar struct ure. The obtained data are also related to two alkoxy-substituted stilbene derivatives 2 and 3 to recognize trends of torsion at the olefinic double b onds which are induced by substituents. Surprisingly, the direct impact of substituents on the torsion angles is negligible in comparison to crystal l attice effects. In contrast to quantum mechanical predictions, neither of t he compounds 2-5 shows in the solid-state weak hydrogen bonding between the oxygen of the alkoxy side chains and the olefinic hydrogens.