Effect of periodic replacement of the heteroatom on the spectroscopic properties of indole and benzofuran derivatives

Atsuya Muranaka, Shuji Yasuike, Ching Yuan Liu, Jyoji Kurita, Naoki Kakusawa, Takashi Tsuchiya, Masako Okuda, Nagao Kobayashi, Yotaro Matsumoto, Kengo Yoshida, Daisuke Hashizume, Masanobu Uchiyama

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)464-473
Number of pages10
JournalJournal of Physical Chemistry A
Volume113
Issue number2
DOIs
Publication statusPublished - 2009 Jan 15
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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