Parallel and Perpendicular Packing in Mixed-Stack Cocrystals of Trimeric Perfluoro-ortho-phenylene Mercury and Benzo[1,2-b:6,5-b′]dithiophene-4,5-dione Derivatives

Seven cocrystals derived from 2,7-substituted benzo[1,2-b:6,5-b']dithiophene-4,5-diones (BDDO) and trimeric perfluoro-o-phenylene mercury (TPPM) exhibit two prominent packing motifs: parallel mixed stacks and T-shaped columnar structures. The varied packing patterns reveal an interplay of noncovalent intermolecular interactions that depend on the nature of the BDDO 2,7-substituents and on the crystallization conditions. Quantum-chemical analyses show little charge-transfer character in the mixed-stack structures, suggesting limited electronic interaction among the mixed TPPM and BDDO constituents. The variations in molecular packing with rather minimal change in chemical structure expose the ability to fine-tune the structure of these molecular cocrystals.