Tunable aggregation-induced circularly polarized luminescence of chiral AIEgens via the regulation of mono-/di-substituents of molecules or nanostructures of self-assemblies
Four chiral AIE-active luminogens (AIEgens) containing tetraphenylethene (TPE) and one or two chiral glutamic moieties connected by thiourea were designed and synthesized. All AIEgens showed tunable aggregation-induced circularly polarized luminescence (AICPL) by adjusting the mono-/di-substituents of molecules or nanostructures of self-assemblies. The enantiotopic mono-substituted compounds (TPE-Glu) exhibited mirror-imaged AICPL signals with the maximal |glum| value of up to 0.02. Interestingly, the di-substituted cis- and trans-isomers showed reverse AICPL signals compared with those of mono-substituted ones. cis- and trans-isomers (TPE-DGlu) showed similar AICPL properties, whose signs of AICPL signals reversed while the water fraction (fw) was more than 80%. The SEM images of their self-assemblies indicated that the AICPL properties should have an intrinsic relation with their molecular structures or self-assembled nanostructures.