Control of the Emission Behaviors of Trifunctional o-Carborane Dyes

A series of organic dyes were synthesized that contain an o-carborane unit in combination with phenanthrene, tolane, and BODIPY moieties. In solution, compound 7a, which has phenanthrene and tolane units, does not emit as a result of an intramolecular charge transfer (ICT) from the emitters to the C1C2 bond of the o-carborane cage, whereas, in the aggregate and solid state, 7a emits intense green light through aggregation-induced emission (AIE). In solution, compound 7b, which has phenanthrene, tolane, and BODIPY units, emits green light from the BODIPY moiety, whereas, in both the aggregate and solid state, it does not emit as a result of the energy transfer from the phenanthrene and tolanes to the neighboring BODIPY units and the successive aggregation-caused quenching (ACQ) mechanism. This work shows that the emission behaviors, the ICT, AIE, energy transfer, and ACQ, of these dyes can be controlled by the substituents at the o-carborane core.