Effect of Periodic Replacement of the Heteroatom on the Spectroscopic Properties of Indole and Benzofuran Derivatives
Effect of Periodic Replacement of the Heteroatom on the Spectroscopic Properties of Indole and Benzofuran Derivatives
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DOI：
10.1021/jp8079843
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发表时间：
2009-01-15
影响因子：
2.9
通讯作者：
Uchiyamat, Masanobu
中科院分区：
文献类型：
--
作者：
Muranaka, Atsuya;Yasuike, Shuji;Uchiyamat, Masanobu
用多种光谱技术结合密度泛函计算研究了吲哚和苯并呋喃同系物的电子结构，其中氮或氧原子被第15和第16族较重的杂原子取代。结果表明，16个苯并杂环化合物的激发能按苯并呋喃(6)、苯并噻吩环(7)、苯并硒环(8)、苯并硫杂菲(9)的顺序向红移。相反，第15族苯并茂、吲哚(1b)、膦吲哚(2b)、精氨酸(3b)、二苯乙烯(4b)和铋(5b)的电子吸收光谱没有表现出这种类型的光谱移动。X射线分析和密度泛函理论(DFT)研究表明，2b-5b在晶相和溶液相中均为弯曲构象。相反，计算了16族杂环的平面结构。利用观测到的光谱性质和含时密度泛函理论(TDDFT)计算，对这些杂环化合物的电子吸收光谱进行了归属。通过分子轨道分析，合理地解释了杂原子取代对电子结构的影响。根据Michl周长模型解释了观察到的杂环的磁性圆二色(MCD)符号花样。
The electronic structures of a homologous series of indole and benzofuran derivatives, in which the nitrogen or oxygen atom is replaced by group 15 and group 16 heavier heteroatoms, have been investigated by means of various spectroscopic techniques coupled with density functional calculations. It was found that the excitation energies of the group 16 benzoheteroles systematically shift to the red in the order of benzofuran (6), benzothiophene (7), benzoselenophene (8), and benzotellurophene (9). In contrast, the electronic absorption spectra of the group 15 benzoheteroles, 1-phenyl derivatives of indole (1b), phosphindole (2b), arsindole (3b), stibindole (4b), and bismuindole (5b), did not exhibit this type of spectral shift. X-ray analysis and density functional theory (DFT) studies revealed that 2b-5b adopt a bent conformation both in the crystalline and in the solution phases. In contrast, planar structures were calculated for the group 16 heterocycles. Using the observed spectroscopic properties and time-dependent density functional theory (TDDFT) calculations, the electronic absorption spectra of the present heterocycles were assigned. A molecular orbital analysis was performed to rationalize the effect of replacement of the heteroatom on the electronic structures. The observed magnetic circular dichroism (MCD) sign patterns of these heterocycles are interpreted according to Michl's perimeter model.