Aggregation-mediated photo-responsive luminescence of cyanostilbene based cruciform AIEgens?

Journal of Materials Chemistry C Pub Date: 2020-12-09 DOI: 10.1039/D0TC05131D

Abstract

Photochromic materials have received tremendous attention owing to their unique photoresponsive behaviour and promising applications as smart materials. Herein, two cyanostilbene based AIEgens with a cruciform topology were synthesized and well characterized. Upon the addition of water, both fluorophores exhibited enhanced emission in the THF/water mixture owing to aggregate formation. In solution, the emission of these AIEgens can be gradually attenuated with blue-shifted absorption after irradiating with 365 nm UV light and recovered on exposure to 254 nm UV light. This phenomenon was attributed to the reversible E/Z isomerization of the cyanostilbene units and confirmed by NMR spectroscopy. By contrast, for the sample in the nano-aggregate or solid state, the emission can be efficiently quenched via [2+2] cycloaddition which had disrupted the conjugation backbone of the chromophore. Photochromic luminescence can also be realized by dispersing the fluorophores in a PMMA matrix and modulated by tuning their concentration in the polymer film. Meanwhile, the cruciform AIEgens also exhibited obvious mechanochromic luminescence in the solid state.

Graphical abstract: Aggregation-mediated photo-responsive luminescence of cyanostilbene based cruciform AIEgens
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