Laser Photolysis of Carboxymethylated Chitin Derivatives in Aqueous Solution. Part 1. Formation of Hydrated Electron and a Long-Lived Radical

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• 作者：Maolin Zhai ; Hisaaki Kudoh ; Guozhong Wu ; Radoslaw A. Wach ; Yusa Muroya ; Yosuke Katsumura ; Naotsugu Nagasawa ; Long Zhao ; and Fumio Yoshii
• 刊名：Biomacromolecules
• 出版年：2004
• 出版时间：March 2004
• 年：2004
• 卷：5
• 期：2
• 页码：453 - 457
• 全文大小：128K
• 年卷期：v.5,no.2(March 2004)
• ISSN：1526-4602

文摘

Laser photolysis experiments on carboxymethylated chitin derivatives, such as carboxymethyl chitin(CM-chitin) and carboxymethyl chitosan (CM-chitosan), in aqueous solution by a 248 nm excimer laserwere carried out for the first time. The transient absorption spectra of photolyzed CM-chitin or CM-chitosansolutions revealed a strong band with the maximum at 720 nm, which was assigned to the hydrated electron(e_aq^- ). In the presence of argon, the e_aq^- decays by reacting with CM-chitin or CM-chitosan, and the rateconstants are (6.1 ± 0.1) × 10⁷ M^-1 s^-1 and (3.7 ± 0.1) × 10⁷ M^-1 s^-1, respectively. Long-lived radicalswith relatively weak absorption intensity were detected in the near-UV region. The absorption band wasnot notably characteristic and showed only an increasing absorption toward shorter wavelengths. It is similarto the signal of CM-chitin or CM-chitosan macroradicals formed by the reaction of CM-chitin orCM-chitosan with an OH radical. It was assigned to CM-chitin^- or CM-chitosan^- macroradicals formedby e_aq^- + CM-chitin or CM-chitosan reaction. CM-chitin aqueous solutions were further examined by pulseradiolysis in order to confirm the site of the long-lived radical.