Synthesis and properties of sterically crowded triarylphosphines bearing anthra- and naphtho-quinones, and their oligomers

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• 作者：Shigeru Sasaki ; Kazunobu Ogawa ; Kazuhiro Nakamura ; Masaaki Yoshifuji ; Noboru Morita
• 关键词：Phosphine ; Quinone ; Redox properties ; UV&ndash ; Vis spectrum ; Charge transfer
• 刊名：Journal of Organometallic Chemistry
• 出版年：1 February, 2014
• 年：2014
• 卷：751
• 期：Complete
• 页码：525-533
• 全文大小：2085 K

文摘

Sterically crowded triarylphosphines bearing anthraquinones were synthesized by Suzuki-Miyaura coupling of arylboronic acids derived from (bromoaryl)phosphines with haloanthraquinones. The anthraquinone bearing the two triarylphosphine moieties at the 2,6-positions shows the smaller difference between the oxidation potential of the triarylphosphine moieties and the reduction potential of the anthraquinone moiety, and the more red-shifted visible absorption responsible for the reddish brown color as compared with the 1,5-derivative. A sterically crowded triarylphosphine-naphthoquinone oligomer composed of alternately aligned three triarylphosphine and four naphthoquinone moieties were also synthesized by repeated Suzuki-Miyaura coupling using arylboronic acids derived from (bromoaryl)phosphines and chloronaphthoquinone derivatives. The ³¹P NMR spectrum of the oligomer consists of several peaks in a narrow range reflecting distribution of the diastereomers arising from the helicity of the propellers composed of the three aromatic rings on the phosphorus atom. The oligomer exhibits a purple color resulting from the intramolecular charge transfer from the triarylphosphine moiety to the neighboring naphthoquinone moiety, and the wavelength and the intensity of the charge transfer band have a demonstrable correlation with the redox potentials and the number of the neighboring triarylphosphine-naphthoquinone pairs, respectively.