Axially Chiral BODIPY DYEmers: An Apparent Exception to the Exciton Chirality Rule
Axially Chiral BODIPY DYEmers: An Apparent Exception to the Exciton Chirality Rule
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DOI：
10.1002/anie.201408398
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发表时间：
2014-12-22
影响因子：
16.6
通讯作者：
Bringmann, Gerhard
中科院分区：
文献类型：
--
作者：
Bruhn, Torsten;Pescitelli, Gennaro;Bringmann, Gerhard
激子手性方法(ECM)被公认为是确定联芳基绝对构型的最佳方法之一。本文针对一个简单的联芳基体系首次报道了这种方法的例外情况。ECD和VCD测量结合DFT(B3LYP/6-311G*)、TDDFT(CAM-B3LYP/6-311G*)和耦合簇(RISCS-CC2)计算确定了轴手性BODIPY DYEmers的绝对构型。ECM不能预测1，1‘-偶联二聚体在500 nm处的强CD偶联的符号。考虑到与500 nm跃迁相关的强跃迁磁偶极子，这一奇特行为得到了合理的解释，这导致了这些化合物中mm耦合的意外优势，而mm耦合的代价是mm耦合。这是第一次强烈的mm耦合阻碍了ECM的使用，但这种行为不应仅限于BODIPY发色团。
The exciton chirality method (ECM) is commonly recognized as one of the best approaches to assign the absolute configuration of biaryls. This paper reports the first exception to this method for a simple biaryl system. ECD and VCD measurements in combination with DFT (B3LYP/6-311G*), TDDFT (CAM-B3LYP/6-311G*), and Coupled-Cluster (RISCS-CC2) calculations were used to determine the absolute configurations of axially chiral BODIPY DYEmers. The ECM fails to predict the sign of the intense CD couplet at 500 nm of the 1,1'-coupled dimer. The odd behavior was rationalized by considering the strong transition magnetic dipole associated with the 500 nm transition, which leads to an unexpected dominance of the mm coupling at the expense of the mm one in these compounds. This is the first case in which a strong mm coupling hampers the use of the ECM, but this behavior should not be restricted to the BODIPY chromophore.