Multi-stimuli-responsive and multimode azoquinoline chiroptical switches

Abstract

Chiroptical switches combine molecular switches and chiral signaling modulation. However, controllable multiresponsive and multistate chiroptical switching are challenging. Herein, we report azoquinoline-based chiroptical switches with multi-stimuli responsiveness and multimode regulation by taking advantage of reversible coordination bonding and dynamic covalent bonding. Introduction of a chiral amine combined with structural rigidification imposed by metal chelation enabled facile creation of chiroptical switches with amplified chirality induction and circular dichroism (CD) outputs. The diverse regulation of chiral signaling was further realized, including the binding/releasing of metal ions, the exchange between different metal ions, and Z/E photoswitching-induced structural interconversion with light. Moreover, the manipulation of the formation, scission, and exchange of dynamic imine bonds offered ample ways for the suppression, amplification, and inversion of CD signals. Multiple control of chiroptical switches exhibiting multimode signaling patterns was thus achieved with metal ions, light, acid/base, and amine nucleophiles. Our results could be beneficial to research on molecular switches, complex systems, chiral catalysts, and intelligent materials.