Acid Stimuli Responsive CPL from Supramolecular Assembly of AIE Molecule

Circularly polarized luminescence (CPL) materials have potential applications in 3D optical displays, information security encryption, sensors, and photoelectric devices because of their inherent advantages of tunable emission, high solid-state fluorescence quantum efficiency, and abundant species. Herein, we construct CPL supermolecular assembly with acid stimuli response by assembling a typical aggregation induced emission (AIE) molecule 9,10-bis(4-pyridyl)anthracene (BP4VA) with a self-assembled chiral molecule 1,3,5-trimesyltrilglutamic acid hexaethyl ester (TMGE). Scanning electron microscope (SEM), transmission electron microscope (TEM), and fluorescence images proved the successful assembly of BP4VA and TMGE. The fluorescent emission peak of the assembly was the same as that of BP4VA in solution, but the intensity was significantly stronger than that of BP4VA in solution due to the aggregation of BP4VA in the assembly. Circular dichroism (CD) spectra of the supermolecular assembly indicate that the chirality can be passed from the chiral molecule TMGE to the achiral AIE molecule BP4VA through the coassembly. The CPL wavelength of the assembly achieves a red-shift after the stimuli of trifluoroacetic acid (TFA) because of the protonation of pyridine on BP4VA, while the morphology of the assembly has no big difference before and after protonation. The study provides an effective strategy to prepare stable acid stimulus responsive CPL materials through the assembly of AIE molecules.