Transcription of chirality in the organogel systems dictates the enantiodifferentiating photodimerization of substituted anthracene

Arnab Dawn, Tomohiro Shiraki, Shuichi Haraguchi, Hiroki Sato, Kazuki Sada, Seiji Shinkai

研究成果: ジャーナルへの寄稿学術誌査読

61 被引用数 (Scopus)

抄録

An organogelator (G) that contains 2-anthracenecarboxylic acid (2Ac) attached covalently to a gelator counterpart that consists of 3,4,5-tris(ndodecan-l-yloxy)benzoic acid by means of a chiral amino alcohol linkage has been synthesized. G acts as an efficient gelator of organic solvents, including mixed solvents and chiral solvents. Photodimers isolated after the photoreaction of the gel samples display different degrees of stereoselectivity. In the gel state, the formation of head-to-head (h-h) photodimers is always favored over head-to-tail (h-t) photodimers. Enantiomeric excess (ee) values of the major h-h photodimers reached as high as -56% in the case of the gels with enantiomeric glycidyl methyl ethers. Here, the solvent chirality is outweighed by the intrinsic chirality of the gelator molecule. The packing of the chromophore in the gel state has been characterized by the absorption and the emission behaviors and their variations during the course of gel-tosol phase transition. Whereas for the hexane gel, emission intensity increases with an increase in temperature, other systems show a decrease in emission intensity. Redshift of the λmax in the gel spectra indicates the J-aggregate arrangement of the chromophores. Chiral transcription in the gel state has been investigated by CD spectroscopy, which shows a decrease in CD intensity during the gel-to-sol phase transition. The X-ray diffraction study clearly differentiates among the gels in terms of the order of molecular arrangements. The gel systems are categorized as strong, moderately strong, and weak, that originate from the cooperative or individual participations of intermolecular hydrogen-bonding and π-π interactions, fine-tuned by the solvent polarity and the gelation temperature. A simple model based on the experimental findings and the molecular preorientation as evidenced by the stereochemistry of the photodimers has been proposed.

本文言語英語
ページ(範囲)3676-3689
ページ数14
ジャーナルChemistry - A European Journal
16
12
DOI
出版ステータス出版済み - 3月 22 2010
外部発表はい

!!!All Science Journal Classification (ASJC) codes

  • 触媒
  • 有機化学

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