Excited state proton transfer in the Cinchona alkaloid cupreidine

文献情報

出版日 2010-08-20

DOI 10.1039/C003419C

インパクトファクター 3.676

著者

Junhong Qian, Albert M. Brouwer

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要旨

Photophysical properties of the organocatalyst cupreidine (CPD) and its chromophoric building block 6-hydroxyquinoline (6HQ) in protic and nonprotic polar solvents (methanol and acetonitrile) were investigated by means of UV-vis absorption, and steady state and time resolved fluorescence spectroscopy. The effects of the catalytically relevant interactions with electrophilic and hydrogen bonding agents (p-toluene sulfonic acid and water) on their spectral characteristics were studied. In neutral CPD in acetonitrile, quenching of fluorescence occurs due to electron transfer from the quinuclidine nitrogen to the excited quinoline chromophore. Protonation suppresses this process, while complexation with water leads to enhanced excited state proton transfer from the 6′-OH group to the quinuclidine nitrogen, and emission occurs from the anionic form of the chromophore. The weakly emitting zwitterionic form of the hydroxyquinoline chromophore is readily formed in methanol, but not in acetonitrile.

掲載誌

Physical Chemistry Chemical Physics

CiteScore: 5.5

自己引用率: 10.3%

年間論文数: 3036

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