Diarylethenes (DAEs) represent an important class of photochromes with notable characteristics, like thermally irreversible photoisomerization and high fatigue resistance. Structural diversification of the DAE scaffold has enabled further refinement of photochromic properties and realization of new applications, ranging from advanced materials to tools for studying biological systems. In particular, methods for synthesizing non-symmetric DAE scaffolds, which are typically more challenging to synthesize than their symmetric counterparts, have grown over the past 20 years. These developments are surveyed in this review, with discussion of how access to these compounds has contributed to the improvement of photochromic properties and paved the way for exploring new applications of DAEs. First, non-symmetric DAE structures are classified and their uses and applications are overviewed. Subsequent sections discuss the main strategies that have been used to access non-symmetric DAEs with examples illustrating the impact of non-symmetric DAEs in the growing field of light-controlled molecular systems.

中文翻译：

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非对称光致变色二芳基乙烯的合成策略。

二芳基乙烯 (DAE) 是一类重要的光致变色材料，具有显着的特性，如热不可逆光异构化和高抗疲劳性。DAE 支架的结构多样化使光致变色特性的进一步细化和新应用的实现成为可能，从先进材料到研究生物系统的工具。特别是，合成非对称 DAE 支架的方法在过去 20 年中得到了发展，这些方法通常比其对称对应物更具挑战性。本综述对这些进展进行了调查，并讨论了这些化合物的使用如何有助于改善光致变色特性，并为探索 DAE 的新应用铺平了道路。第一的，对非对称 DAE 结构进行了分类，并概述了它们的用途和应用。随后的部分讨论了用于访问非对称 DAE 的主要策略，并举例说明了非对称 DAE 在光控分子系统不断发展的领域中的影响。