Incorporation of Coronene into Cage-like Porous Organic Salts and Induction of its Room-Temperature Phosphorescence in Air

Coronene emits phosphorescence only at cryogenic temperatures in the absence of oxygen. To achieve room-temperature phosphorescence (RTP), coronene has been incorporated into various host materials to prevent non-radiative deactivation of the incorporated molecules. Among host materials, crystalline porous materials homogeneously incorporate luminescent molecules and prevent their aggregation. Therefore, they have attracted attention as potential host materials. Although coronene incorporated into a crystalline porous material exhibited RTP in previous studies, the host material exhibited high affinity for oxygen, allowing the expression of RTP only under anoxic conditions. Therefore, RTP has not been achieved in air. Herein, we incorporate coronene into cage-like sodalite-type porous organic salts (s-POSs) composed of tetrasulfonic acid with an adamantane core (4,4',4'',4'''-[adamantane-1,3,5,7-tetrayl]tetrabenzenesulfonic acid; AdPS) and triphenylmethylamines modified with substituents at the para-position of the benzene rings (TPMA-X, X=methyl [Me], Br, I), which have low oxygen affinities and different degrees of heavy-atom effects on incorporated coronene. The combination of the oxygen barrier due to the low affinity of s-POSs for oxygen and the external heavy-atom effect of bromine and iodine exposed on the pore surface enabled the incorporated coronene to exhibit RTP in air (phosphorescence lifetime with more than microseconds).