UVC‐to‐NIR‐II Ultra‐Broadband Response Photochromism of Stilbene Enabled by Donor‐Acceptor Complexation Strategy Through One‐Step Mechanochemical Synthesis

Abstract

We introduce a supramolecular approach to substantially expand the response wavelength of photoswitchable stilbene( E ) from UVC (274 nm) to NIR‐II (1064 nm) region, which doesn't depend on E ‐to‐ Z photoisomerization. Stilbene( E ) acts as an electron donor and is co‐assembled with a matched acceptor (e.g., F x TCNQ, x = 1/2/4) to form a solid complex with a loose stack and broadband absorption of 250–1100 nm through one‐step mechanochemical synthesis. Reversible green‐to‐yellow chromism is observed for the complex exposed to 808 nm‐light irradiation/heating treatment, which corresponds to the disappearance/appearance of the absorption band of ∼550‐1100 nm. This behavior is attributed to photo‐induced ultrafast torsion (<0.23 ps) of the stilbene( E ) skeleton and resulting destruction of donor‐acceptor π‐π stacking, and subsequent heating‐induced recovery. Besides, the complex can also serve as a UV‐excited fluorescence switch and NIR‐photothermal material. Hence, donor‐acceptor complexation effectively reduces the photo‐activation energy of stilbene( E ) by π‐π interaction and provides a promising route to design a multi‐functional photoswitch with ultra‐broadband light response.