Correlating the Structural and Photophysical Properties of Ortho , Meta , and Para‐Carboranyl–Anthracene Dyads

The role of the carborane isomer is investigated on the structural and photophysical properties of molecules comprising a carborane cluster and a conjugated organic moiety is investigated by synthesizing isomeric o‐, m‐, and p‐carboranyl‐anthracene donor–acceptor dyads. While appending a carborane leads to emission from a low energy intramolecular charge transfer state for the o‐isomer, as well as emission from an excited state localized on the anthracene, this is not the case for the m‐ and p‐carborane derivatives. This difference is attributed to a lower electron affinity for the latter two isomers. However, adding both m‐ and p‐ deforms the aromatic backbone and increases its structural rigidity, reducing non‐radiative decay pathways and hence enhancing photoluminescence quantum efficiency relative to anthracene