Molecular photoswitches comprise chromophores that can be interconverted reversibly with light between two states with different photochemical and physicochemical properties. This feature renders them useful for diverse applications, ranging from materials science, biology (specifically photopharmacology) to supramolecular chemistry. With new and more challenging systems to control, especially extending towards biomedical applications, using visible or near-infrared light for photoswitch activation becomes vital. Donor–acceptor Stenhouse adducts are a novel class of visible light-responsive negative photochromes that provide a possible answer to current limitations of other photoswitch classes in the visible and NIR window. Their rapid development since their discovery in 2014, together with first successful examples of applications, demonstrate both their potential and areas where improvements are needed. A better understanding of DASA characteristics and its photoswitching mechanism has revealed that they are in fact a subset of a more general structural class of photochromes, namely Stenhouse photoswitches. This tutorial review aims at providing an introduction and practical guide on DASAs: it focuses on their structure and synthesis, provides fundamental insights for understanding their photoswitching behavior and demonstrates guiding principles for tailoring these switches for given applications.

中文翻译：

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Stenhouse光开关的（光）化学性质：指导原则和系统设计

分子光开关包含可以在具有不同光化学和物理化学性质的两个状态之间通过光可逆地相互转换的生色团。此功能使它们可用于多种应用，从材料科学，生物学（特别是光药理学）到超分子化学。随着新的更具挑战性的系统的控制，尤其是向生物医学应用的扩展，使用可见光或近红外光进行光开关激活变得至关重要。供体-受体Stenhouse加合物是一类新型的可见光响应性负色光色素，可为可见光和NIR窗口中其他光电开关类别的当前局限性提供可能的答案。自2014年被发现以来，它们发展迅速，并首次成功地应用了一些示例，展示其潜力和需要改进的领域。对DASA特性及其光开关机制的更好理解表明，它们实际上是更通用的光致变色剂结构类型（即Stenhouse光开关）的子集。本教程的回顾旨在提供有关DASA的介绍和实践指南：重点在于其DASA的结构和合成，提供了解其光电开关行为的基础见解，并演示针对给定应用量身定制这些开关的指导原则。