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

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