Structural Study of Hydrogen-Bond Driven Cocrystallization of Pyridyl-Bithiophene Based Compounds

Thiophene-based compounds have been extensively studied due to their electronic and optical properties, which find application in organic semiconductors. There are multiple reports describing the fine-tuning of these and other specific material properties. In this study, we conduct a systematic cocrystallization screen of two thiophene-based compounds, 5,5′-di(pyridin-3-yl)-2,2′-bithiophene (T1) and 5,5′-di(pyridin-4-yl)-2,2′-bithiophene (T2) combined with eight coformers. Molecular electrostatic potential surface (MEPS) calculations were used to guide the cocrystallization outcomes, which were compared to experimentally observed results via IR, NMR, TGA, and single-crystal X-ray diffraction. The two targets cocrystallized with all the eight coformers and single crystals were obtained in eight instances. The single-crystal structure analysis results matched the MEPS predicted homomeric and heteromeric synthons in all the cases except T2:4-hydroxybenzoic acid. The differences observed in the hydrogen-bond interactions for these combinations provided a promising indication of using cocrystallization as a tool to manipulate the target compounds' electronic and optical properties.