Correlating the Structural and Photophysical Properties ofOrtho,Meta, andPara-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 isomerico-,m-, andp-carboranyl-anthracene donor-acceptor dyads. While appending a carborane leads to emission from a low energy intramolecular charge transfer state for theo-isomer, as well as emission from an excited state localized on the anthracene, this is not the case for them- andp-carborane derivatives. This difference is attributed to a lower electron affinity for the latter two isomers. However, adding bothm- andp- deforms the aromatic backbone and increases its structural rigidity, reducing non-radiative decay pathways and hence enhancing photoluminescence quantum efficiency relative to anthracene.