Interplay of C–H⋯F and halogen bonding interactions for tunable room-temperature phosphorescence in iododiphenylacetylene systems

Abstract

Efficient room-temperature phosphorescence (RTP) often depends on specific intermolecular interactions, such as C–H⋯F and halogen bonding interactions; however, their role in fluorinated diphenylacetylene derivatives remains unclear. In this study, we systematically synthesized a series of iododiphenylacetylene derivatives containing fluorine or methoxy substituents to elucidate the relationships between intermolecular interactions, molecular packing, and RTP properties. Single-crystal X-ray diffraction and cyclic voltammetry were employed to investigate their packing structures and estimate the electronic properties, respectively, and their photophysical properties were examined. Both C–H⋯F and halogen bonding interactions contributed to enhancing RTP; however, C–H⋯F interaction induced by fluorine atoms played a more significant role in increasing the phosphorescence intensity and efficiency. Moreover, the combination of both intermolecular interactions resulted in a synergistic improvement in RTP properties. These findings provide valuable guidelines for designing and developing efficient diphenylacetylene-based RTP materials.