Azetidinyl substituents have been recently used to improve the fluorescence quantum yield of several classes of fluorophores. Herein, we demonstrate that other useful photochemical processes can be modulated using this strategy. In particular, we prepared and measured the quantum yield of photorelease of a series of 7-azetidinyl-4-methyl coumarin esters and compared it to their 7-diethylamino and julolidine-fused analogues. The efficiency of the photorelease reactions of the azetidinyl-substituted compounds was 2- to 5-fold higher than the corresponding diethylamino coumarins. We investigated the origin of this effect in model fluorophores and in the photoactivatable esters, and found that H-bonding with the solvent seems to be the prominent deactivation channel inhibited upon substitution with an azetidinyl ring. We anticipate that this substitution strategy could be used to modulate other photochemical processes with applications in chemical biology, catalysis and materials science.

中文翻译：

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通过氮杂环丁烷基取代提高了光不稳定香豆素的功效†

氮杂环丁烷基取代基最近已用于提高几类荧光团的荧光量子产率。在本文中，我们证明了使用该策略可以调节其他有用的光化学过程。特别是，我们准备并测量了一系列7-氮杂环丁烷基-4-甲基香豆素酯的光释放量子产率，并将其与其7-二乙氨基和julolidine融合的类似物进行了比较。氮杂环丁烷基取代的化合物的光释放反应的效率比相应的二乙氨基香豆素高2至5倍。我们调查了这种效应在模型荧光团和可光活化酯中的起源，发现与溶剂的氢键似乎是被氮杂环丁烷基环取代后受到抑制的主要失活通道。