Histidine Proton Shuttle-Initiated Switchable Inversion of Circularly Polarized Luminescence.

Switchable inversion of the sign of circularly polarized luminescence (CPL) in chiral supramolecular systems has gained remarkable interest because of its role in understanding the chirality-switching phenomena in biological systems and developing smart chiral luminescent materials. Herein, inspired by the histidine proton shuttle in natural enzymes, we synthesized a histidine π-gel (PyCH) and realized reversible inversion of supramolecular chirality and CPL by receiving and then transferring a proton. It was found that in the course of histidine protonation by adding an external proton source, the transcription of intrinsic molecular chirality of PyCH to the supramolecular level biased, achieving dynamic control over the PyCH gel with left-handed CPL inversed into the right-handed one. The mechanism study revealed that the supramolecular chirality and CPL inversion are mainly affected by the cooperation adjustment of hydrogen bonds and π-π stacking upon histidine protonation and deprotonation, which causes the re-orientations of pyrene chromophores. This work sets up an alternative effective method to fabricate tunable CPL-active materials while using the same chiral small molecules, which provides a new insight into developing bio-inspired switchable supramolecular materials.