Photon upconversion of a rigid anthracene dyad doubly-linked with a core structure of Tröger’s base unit

Triplet–triplet annihilation (TTA)-assisted photon upconversion (PUC) was demonstrated to occur in a CH2Cl2 solution of energy donor platinum octaethylporphyrin (PtOEP) and energy acceptor dyad An=CTB=An containing two anthracene moieties (An) doubly-linked to a core framework of Tröger’s base (CTB) unit. Analysis of the PUC behavior of An=CTB=An revealed that it has a selectivity (f) of 0.43 for formation of the light emitting 1A* state via fusion of the triplet pair (TT). The magnitude of the f value indicates that, unlike the situation in more flexible dyads, restriction of molecular motion caused by the rigid structure of An=CTB=An suppresses competitive fusion of the 3(TT) and 5(TT) states that lead to 3A* and A, and/or non-radiative deactivation.