Conformationally Gated Interconversion of Photophysical Pathways Enables Invertible Circularly Polarized Luminescence

Abstract

Precise control of excited-state chirality in supramolecular aggregates is hindered by the rapid erasure of ground-state chiral information via ultrafast structural relaxation and energy dissipation. Here we report a strategy to overcome this limitation using 1,4-disubstituted benzene-based molecular rotors engineered for maximal rotational freedom. These motifs self-assemble into loosely packed architectures that simultaneously suppress intermolecular quenching and steric strain, thereby unlocking an aggregated twisted intramolecular charge transfer (A-TICT) state absent in tightly stacked analogues. Through femtosecond transient absorption and time-resolved circularly polarized luminescence (CPL) spectroscopy, we resolve two distinct emissive pathways: a short-lived (picosecond), right-handed CPL at 460 nm from aggregation-induced emission (AIE) species, and a long-lived (nanosecond), left-handed CPL at 520 nm from the A-TICT state. Solvent polarity dynamically governs the population balance and interconversion kinetics between the two states, inducing dual inversions in the steady-state CPL signal. This conformationally gated switching arises from the synergistic interplay of AIE and A-TICT, where structural flexibility permits excited-state evolutions inaccessible to rigid systems. Our findings provide a design principle for smart chiroptical materials with externally tunable handedness, lifetime, and temporal response, and support the applications of such materials in chiral sensing, optoelectronic devices, and dynamic information encoding.