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As an important organic photo-functional material, spirooxazine usually does not exhibit photochromism in the solid state since the intermolecular π-π stacking impedes photoisomerization. Developing photochromic spirooxazine in the solid state is crucial for practical applications but is still full of challenges. Here, we design and synthesize a series of spirooxazine derivatives (SO1-SO4) with bulky aromatic substituents at the 4- and 7-positions of the skeleton, providing a large volume for them to undergo solid-state photochromism under mild conditions. All compounds SO1-SO4 exhibit tunable solid photochromism without ground colors, excellent fatigue resistance, and high thermal stability. Notably, it takes only 15 s for SO4 to reach the saturation of absorption intensity, representing the fastest solid-state photoresponse of spirooxazines to the best of our knowledge. X-ray crystal structures of the intermediate compound SO0 and the products SO1-SO2 as well as the computational studies suggest that the bulky aromatic groups can lead to a hypochromic effect, allowing for the photochromism of SO in the solid state. The ideal photochromic properties of these spirooxazines open a new avenue for their applications in UV printing, Quick Response (QR) code, and related fields. This article is protected by copyright. All rights reserved.

Photo-assisted therapy has been an advancing branch in the fields of modern theranostics and nanomedicine, holding observable superiorities such as noninvasiveness, deep tissue penetration, and spatial precision. Aggregation-induced emission luminogens (AIEgens) have emerged as powerful fluorescent materials and organic optical agents capable of performing therapeutic effects under light activation. In this review, we underscore the elaborate design and fabrication of AIEgen-based supramolecular materials for applications in the scope of photo-assisted therapy, including photothermal therapy, photodynamic therapy, and photo-induced reactions. With the aid of supramolecular self-assembly, AIE materials are endowed with higher biocompatibility, better specificity, external stimuli responsiveness, and integrated functionalities. AIEgen-based self-assembled materials categorized by different supramolecular driving forces are summarized with their respective features in both structures and therapeutic effects fully described. With these highly adjustable physicochemical properties of supramolecular assemblies, the functions of such AIE materials can be considerably expanded and optimized, also opening up possibilities for controllable multimodal theranostics. In the conclusion part, perspectives and remaining challenges in this research area are discussed.