A Laser Flash Photolysis Study of Fenofibric Acid in Aqueous Buffered Media: Unexpected Triplet State Inversion in a Derivative of 4-Alkoxybenzophenone¶
作者:Gonzalo Cosa、S. Purohit、J. C. Scaiano、Francisco Boscá、Miguel A. Miranda
DOI:10.1562/0031-8655(2002)075<0193:alfpso>2.0.co;2
日期:——
suggest that in aqueous media the triplet state of FA has a π,π* character, in comparison with an n,π* character in organic media. Further, the known chemistry of the triplet, including decarboxylation and hydrogen abstraction, occurs predominantly from the n,π* state, and as a consequence, activation energies are higher when the lowest triplet has a π,π* character. Photoionization is more important in
摘要 非诺贝特酸 (FA) 水溶液在 pH 7.4 时的激光激发表明形成了两个反应中间体,三重态和水合电子。前者在水中的寿命比在乙腈中的寿命长;它的阴离子形式通过脱羧作用不可逆地衰变,产生在重排之前或之后质子化的碳负离子。几项光谱和猝灭研究表明,与有机介质中的 n,π* 特征相比,在水性介质中,FA 的三重态具有 π,π* 特征。此外,三重态的已知化学反应,包括脱羧和夺氢,主要发生在 n,π* 状态,因此,当最低的三重态具有 π,π* 特征时,活化能更高。光电离在水性介质中比在有机介质中更重要,并且涉及双光子过程。水合电子被 FA 捕获,质子化后产生相应的羰基自由基。