The Influence of the Side Chain Length on −OCH₃−π Interactions Determining the Crystal Packing of Four Substituted 1,4-Bis(α-styryl)benzenes

The crystal structures of E,E-1,4-bis[2-(2,4,6-trimethoxyphenyl)ethenyl]-2,5-dimethoxybenzene (1), E,E-1,4-bis[2-(2,4,6-trimethoxyphenyl)ethenyl]-2,5-diisopropoxybenzene (2), E,E-1,4-bis[2-(2,4,6-trimethoxyphenyl)ethenyl]-2,5-dihexoxybenzene (3), and E,E-1,4-bis[2-(2,4,6-trimethoxyphenyl)ethenyl]-2,5-bis(2-phenylethoxy)benzene (4) are reported. A weak intramolecular hydrogen bond between protons on the olefinic link and the ortho-methoxy groups on the adjacent benzene rings is commented on. In general, however, the crystal packing for these structures is primarily determined by weak −OCH3−π interactions. Their numbers change with the structure and length of the side chains and with the accommodation of the extended chains in the lattice. A discussion on the effects of these interactions on the possibility of lattice formation explains why these four compounds crystallize and several similar ones with different alkoxy side chains do not.