偶氮-硼氟开关的溶剂依赖性反应活性。

Solvent-dependent reactivity of azo-BF switches.

作者信息

Qi Qingkai, Fu Heyifei, Peng Lingya, Patra Shefali, Liu Xiaogang, Aprahamian Ivan

机构信息

Department of Chemistry, Dartmouth College Hanover New Hampshire 03755 USA

Jiangsu Collaborative Innovation Center of Biomedical Functional Materials, School of Chemistry and Materials Science, Nanjing Normal University Nanjing 210023 China.

出版信息

Chem Sci. 2025 Aug 27. doi: 10.1039/d5sc05042a.

Abstract

Azo-BF complexes are visible and near-infrared (NIR) light-activated photoswitches showcasing versatility in applications ranging from energy storage to three-dimensional displays. While highly appealing as molecular switches, factors that affect their photophysical properties and solution-state reactivity still need to be teased out. In this paper, we present the synthesis and characterization of two azo-BF analogues (1 and 2), each modified with structurally distinct dimethylamine-substituted naphthalene moieties. In addition to investigating the effect of the π-system expansion on the photophysical and photoswitching properties of the system, we also elaborate on the stability (, whether they undergo solvolysis or 1,2-BF shift) of the switches in different solvents. Specifically, switch 1 absorbs in the NIR region, enabling its activation with 700 nm light, while switch 2 exhibits enhanced separation between the and isomer absorption bands, resulting in an improved photostationary state. As for the solvent effect, we discovered that polar aprotic solvents induce an intramolecular 1,2-BF shift in both switches, transforming the azo-BF photoswitches into boron difluoride hydrazone fluorophores, whereas polar protic solvents facilitate the solvolysis of the azo-BF into the starting hydrazone derivative. In the former, the donor number of the solvent is a major factor in determining the obtained outcome, while in the latter, it is the solvent's hydrogen-bond donation capability. These insights into the design strategy and solvent-mediated reactivity of azo-BFs will contribute to their further development into efficient NIR-responsive photoswitches, paving the way for innovative applications in smart materials and molecular devices.

摘要

偶氮 - BF配合物是可见光和近红外(NIR)光激活的光开关,在从能量存储到三维显示等一系列应用中展现出多功能性。尽管作为分子开关极具吸引力,但影响其光物理性质和溶液态反应性的因素仍有待梳理清楚。在本文中,我们展示了两种偶氮 - BF类似物(1和2)的合成与表征,每种类似物都用结构不同的二甲胺取代萘基部分进行了修饰。除了研究π - 体系扩展对该体系光物理和光开关性质的影响外,我们还详细阐述了这些开关在不同溶剂中的稳定性(即它们是否会发生溶剂解或1,2 - BF迁移)。具体而言,开关1在近红外区域吸收,能够用700 nm光激活,而开关2在反式和顺式异构体吸收带之间表现出增强的分离,从而导致光稳态得到改善。至于溶剂效应,我们发现极性非质子溶剂会在两种开关中诱导分子内1,2 - BF迁移,将偶氮 - BF光开关转化为二氟化硼腙荧光团,而极性质子溶剂则促进偶氮 - BF溶剂解为起始腙衍生物。在前者中,溶剂的给体数是决定所得结果的主要因素,而在后者中,是溶剂的氢键给体能力。这些对偶氮 - BF设计策略和溶剂介导反应性的见解将有助于它们进一步发展成为高效的近红外响应光开关,为智能材料和分子器件中的创新应用铺平道路。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/9927/12394902/8d45900d5d64/d5sc05042a-f1.jpg

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