Diazocines, a type of photoswitch molecules, are distinguished by their unique conformation and photochromic properties. The molecular engineering of diazocines, especially π-extended ones, remains challenging due to limited synthesis methods. Here, we develop three π-fused diazocines ( BAZO-1, BAZO-2 and BAZO-3) via Bischler-Napieralski cyclization. Their isomerizations (Z ⇆ E) are switchable under visible light sources (427 nm and 630 nm). The size of π-extension exhibits a significant influence on the isomerization process. The biggest four-fold ring-closure diazocine ( BAZO-3) shows the fastest conversion rate (Z → E). Notably, the half-life time of BAZO-3 is 14.6 times higher than that of the two-fold ring-closure BAZO-1. Thus, BAZO-3 acts as a molecular tweezer based on double N-embedded pyrene units, allowing it to bind to pyrene through supramolecular interactions. This work may pave the way for designing novel photoswitches with long half-life and light-controlled properties.

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中文翻译：

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具有可控光开关特性的 π 稠合重氮辛分子镊子

重氮辛是一种光开关分子，以其独特的构象和光致变色特性而著称。由于合成方法有限，重氮辛的分子工程，特别是π-延伸的重氮辛的分子工程仍然具有挑战性。在这里，我们开发了三种 π 稠合重氮辛（ BAZO-1、BAZO-2和 巴佐-3）通过 Bischler-Napieralski 环化。它们的异构化 ( Z ⇆ E ) 在可见光源（427 nm 和 630 nm）下可切换。 π-延伸的大小对异构化过程有显着影响。最大的四重闭环重氮辛（ 巴佐-3) 显示最快的转换率 ( Z → E )。值得注意的是，半衰期 巴佐-3比两倍闭环高14.6倍 巴佐-1。因此， 巴佐-3作为基于双氮嵌入芘单元的分子镊子，使其能够通过超分子相互作用与芘结合。这项工作可能为设计具有长半衰期和光控特性的新型光电开关铺平道路。

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