Multiparameter Fluorescence Regulation via Mechanical Motion in Aggregation-Induced-Emission-Active Rotaxanes

Abstract We present a mechanically interlocked fluorescence switching platform that enables simultaneous, reversible control over both emission wavelength and intensity through acid/base-driven macrocycle shuttling. Our design, based on a TPE-centered rotaxane architecture, integrates pyridinium-mediated ICT and secondary ammonium recognition sites, creating an environment-sensitive fluorophore coupled to a stimuli-responsive mechanical element. This system operates via three synergistic mechanisms triggered by macrocycle translocation: modulation of the ICT state through microenvironmental polarization, enhancement of emission via confinement-induced restriction of intramolecular motion, and suppression of nonradiative decay through steric blocking of photoinduced electron transfer. By unifying structural precision with dynamic responsiveness, this strategy overcomes key limitations of conventional covalent or aggregation-based approaches and provides a generalizable blueprint for the design of programmable luminescent materials.