Methanol dynamically activated room-temperature phosphorescence from a twisted 4-bromobiphenyl system

Abstract

Crystal engineering is employed widely in developing metal-free room-temperature phosphorescence (RTP) materials,buttheweakresponsiveness inrigid stateand poor selectivity during crystallization limit the research of RTP materials with specific recognition properties. Herein, based on multicomponent crystallization and the deformation of phosphor, we have developed a galactose-functionalized polyhydric compound (BHB) with a twisted 4-bromobiphenyl structure, to realize methanol selectively activated "off-on" RTP system. Methanol molecules selectively formed solvate with BHB and rigidified the crystal structure by enriching intermolecular noncovalent interactions. Meanwhile, the distortion of the biphenyl group facilitated the intersystem crossing process effectively, alongside the heavy-atom effect from the bromo substitute, thereby, activating the RTP of BHB. Thus our current research approach realizes RTPmaterials with selective recognition function by controlling multiple noncovalent interactions such as hydrogen and halogen bonding of molecular systems with structurally distorted phosphors.