A chiral multibrominated triangular macrocycle for modulating circularly polarized phosphorescence

Abstract

Pure organic circularly polarized room-temperature phosphorescence (CP-RTP) materials hold great promise for applications in bioimaging and information encryption. However, achieving CP-RTP with tunable emission colors remains a formidable challenge. Herein, we present a novel approach for constructing tunable CP-RTP materials utilizing a macrocyclic supramolecular strategy. We synthesized a pair of chiral triangular macrocyclic enantiomers, (6R/S)-PMDI, via the condensation of (R,R)- or (S,S)-trans-1,2-diaminocyclohexane with 1,4-dibromo-2,3,5,6-tetracarboxybenzene. The chirality of the macrocycle originates from the rigid diamine unit. This triangular macrocycle exhibits weak fluorescence in solution, and its solid powders are non-luminescent. Remarkably, doping it into a poly(methyl methacrylate) (PMMA) polymer matrix successfully achieved CP-RTP. Furthermore, supramolecular assembly of the triangular macrocycle with the electron-rich guest 9-phenylcarbazole (9-Pcbz) endowed the resulting assemblies with red CP-RTP, which can be attributed to the significant intermolecular charge-transfer (CT) interactions. The supramolecular strategy presented in this work provides an effective platform for the development of color-tunable CP-RTP materials.