Two isomorphous azastilbene derivatives: 1-(2-chlorobenzyl)-4-[(E)-2-(4-hydroxyphenyl)ethenyl]pyridinium chloride and 1-(2-bromobenzyl)-4-[(E)-2-(4-hydroxyphenyl)ethenyl]pyridinium bromide.

ABSTRACT

The crystal structures of the two title (E)-stilbazolium halogenates, C(20)H(17)ClNO(+)·Cl(-) and C(20)H(17)BrNO(+)·Br(-), are isomorphous, with an isostructurality index of 0.985. The azastyryl fragments are almost planar, with dihedral angles between the benzene and pyridine rings of ca 4.5°. The rings of the benzyl groups are, in turn, almost perpendicular to the azastyryl planes, with dihedral angles larger than 80°. The cations and anions are connected by O-H...X(-) (X = halogen) hydrogen bonds. The halide anions are `sandwiched' between the charged pyridinium rings of neighbouring molecules, and weak C-H...O hydrogen bonds and C-H...X and C-H...π interactions also contribute to the crystal structures.