High-Throughput Single-Molecule Spectroscopy Resolves the Conformational Isomers of BODIPY Chromophores
High-Throughput Single-Molecule Spectroscopy Resolves the Conformational Isomers of BODIPY Chromophores
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DOI：
10.1021/acs.jpclett.9b02250
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发表时间：
2019-11-07
影响因子：
5.7
通讯作者：
Raymo, Francisco M.
中科院分区：
文献类型：
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作者：
Sansalone, Lorenzo;Zhang, Yang;Raymo, Francisco M.
硼二吡咯亚甲基(BODIPY)发色团通过反式构型的烯烃桥连接到苯并恶唑、苯并噻唑或硝基苯并噻唑杂环上。在溶液中，围绕烯桥两侧的两个[C-C]键发生旋转，动力学很快，导致每个化合物的四个构象异构体平衡。溶液中的系综光谱测量无法区分共存的异构体。相反，它们显示了平均吸收和发射带，后者依赖于激发波长。利用高通量单分子光谱学，观察到玻璃衬底上的每个化合物都有两个具有不同光谱质心的主要单分子群体。计算分析表明，这两组分子是构象异构体，其BODIPY发色团在其[C-C]键与烯烃桥的[C-C]键周围有反平面和近平面排列。因此，对多个单分子发射光谱的统计分析可以区分立体异构体，否则单靠系综测量是不可能区分的。
A borondipyrromethene (BODIPY) chromophore is connected to a benzoxazole, benzothiazole, or nitrobenzothiazole heterocycle through an olefinic bridge with trans configuration. Rotation about the two [C-C] bonds flanking the olefinic bridge occurs with fast kinetics in solution, leading to the equilibration of four conformational isomers for each compound. Ensemble spectroscopic measurements in solutions fail to distinguish the coexisting isomers. They reveal instead averaged absorption and emission bands with dependence of the latter on the excitation wavelength. Using high-throughput single-molecule spectroscopy, two main populations of single molecules with distinct spectral centroids are observed for each compound on glass substrates. Computational analyses suggest the two populations of molecules to be conformational isomers with antiperiplanar and periplanar arrangements of the BODIPY chromophores about its [C-C] bond to the olefinic bridge. Thus, statistical analysis of multiple single-molecule emission spectra can discriminate stereoisomers that would otherwise be impossible to distinguish by ensemble measurements alone.