Controlling the S1 Energy Profile by Tuning Excited-State Aromaticity
Controlling the S1 Energy Profile by Tuning Excited-State Aromaticity
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DOI：
10.1021/jacs.0c05611
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发表时间：
2020-09-02
影响因子：
15
通讯作者：
Saito, Shohei
中科院分区：
文献类型：
--
作者：
Kotani, Ryota;Liu, Li;Saito, Shohei
最低单重激发态（S-1）能量分布的形状在光化学和相关材料科学领域中是至关重要的。在这里，我们展示了一种新的方法来控制的S-1能量分布的形状依赖于调整激发态芳香性（ESA）的水平。在一系列的荧光π-扩大氧杂环庚三烯，能量降低伴随着S-1的平面构象的变化变得不那么明显与较低的ESA水平。利用地球物理数据定量估算了ESA的稳定化能为10-20 kcal/mol。时间分辨荧光光谱揭示了S-1中非常快的平坦化动力学。的时间常数被估计为短于1 ps，无论分子大小和水平的ESA，表明无障碍的S-1平面化内oxepin系列。
The shape of the lowest singlet excited-state (S-1) energy profile is of primary importance in photochemistry and related materials science areas. Here we demonstrate a new approach for controlling the shape of the S-1 energy profile which relies on tuning the level of excited-state aromaticity (ESA). In a series of fluorescent pi-expanded oxepins, the energy decrease accompanying the bent-to-planar conformational change in S-1 becomes less pronounced with lower ESA levels. Stabilization energies following from ESA were quantitatively estimated to be 10-20 kcal/mol using photophysical data. Very fast planarization dynamics in S-1 was revealed by time-resolved fluorescence spectroscopy. The time constants were estimated to be shorter than 1 ps, regardless of molecular size and level of ESA, indicating barrierless S-1 planarization within the oxepin series.