Supramolecular Polymerization of Triphenylamine[3]arenes for Switchable and Stimuli-Responsive Chiroptical Properties.

Abstract

The design of advanced photonic materials with integrated stimuli-responsive properties remains coveted yet challenging. Herein, we demonstrate that chiral supramolecular assembly of triphenylamine[3]arenes (TPA[3]s) offers an efficient and modular solution to address this challenge. Despite intrinsically nonplanar and conformationally flexible macrocyclic scaffold, peripheral chiral alkyl chains direct TPA[3]s to self-assemble into long-range one-dimensional (1D) nanofibers, as confirmed by transmission electron microscopy and atomic force microscopy, ultimately giving rise to intense blue circularly polarized luminescence (CPL) with a glum of 1.2 × 10-3 and a fluorescence quantum yield of 48%. Benefiting from the triphenylamine cores, the resulting supramolecular polymers exhibit reversible CPL switching upon acid-base stimulation. Notably, TPA[3]s readily undergo rapid photo-induced radical generation in dilute monomeric solution, whereas this process is significantly suppressed in the supramolecular assemblies due to molecular confinement. Combining spectroscopic analyses with coarse-grained molecular dynamics simulations reveals that the formation of air-stable TPA radical cations disrupts the chiral packing, leading to disassembly of supramolecular polymers and the concomitant irreversible loss of CD and CPL signals. These findings establish supramolecular polymerization as a versatile strategy for organizing macrocyclic arenes into ordered 1D chiral assemblies with multi-responsive CPL properties, while providing general design principles for photoresponsive chiral optoelectronic systems.