Properties of o-Carborane Triads: Non-covalent σ…π Interactions and Intermolecular Charge Transfer

Two ortho-carborane triads, p-BrPh-oCB-PhEPy (3), where p-BrPh is p-bromobenzene, and DMA-oCB-PhEPy (4), where DMA is p-N,N-dimethylaniline, PhEPy is 1-(p-phenylethynyl)pyrene, were studied in solution, as single crystals, and in the solid state (photophysical measurements). Both compounds exhibited aggregation-induced emission (in solution, or in the solid state). The crystal structures of both triads exhibit interactions between pyrene units and the carborane (CB) moiety, resulting in intermolecular charge-transfer between the pyrene units and the o-carborane moiety. This interaction significantly influences crystallization, leading to distinctive crystallographic packing patterns. Remarkably, these molecules display multiple emissive species, positioning them as potential candidates for single molecule white-light emission and thermally-activated delayed fluorescence (TADF).