Influence of Halogen Bonding Interactions in Crystalline Networks of Tetraarylethylene Halobenzoyl Esters

Solid state halogen bonding interactions have been examined
in
structurally similar tetratopic haloarenes bearing a common tetraphenylethylene
core. This study was designed with the aim of providing insight into
the relative importance of fundamental solid state halogen bonding
interactions (i.e., halogen···halogen, halogen···π,
and halogen···carbonyl) in systems devoid of strong
hydrogen bonding groups. The substrates used in this study all featured
four halobenzoate substituents (halogen = Br or I) attached to the
four para positions of tetraphenylethylene with conformationally flexible
ester linkages. A total of nine crystal structures from five different
tetraarylethylene substrates were obtained. While distinct and unique
X···O and X···π halogen bonding
interactions were identified in each structure, all structures displayed
nominally similar packing arrangements generally consisting of one-dimensional
ribbons aligned to generate non-interpenetrating two-dimensional sheets.
This feature may be a consequence of extensive edge-to-face arene–arene
interactions found in each structure and may indicate a greater structure-determining
role for aryl-H···π interactions relative to
halogen bonding contacts in this system.