Laser photolysis of carboxymethylated chitin derivatives in aqueous solution. Part 1. Formation of hydrated electron and a long-lived radical.
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 laser were carried out for the first time. The transient absorption spectra of photolyzed CM-chitin or CM-chitosan solutions revealed a strong band with the maximum at 720 nm, which was assigned to the hydrated electron (eaq-). In the presence of argon, the eaq- decays by reacting with CM-chitin or CM-chitosan, and the rate constants are (6.1 +/- 0.1) x 10(7) M(-1) s(-1) and (3.7 +/- 0.1) x 10(7) M(-1) s(-1), respectively. Long-lived radicals with relatively weak absorption intensity were detected in the near-UV region. The absorption band was not notably characteristic and showed only an increasing absorption toward shorter wavelengths. It is similar to the signal of *CM-chitin or *CM-chitosan macroradicals formed by the reaction of CM-chitin or CM-chitosan with an OH* radical. It was assigned to *CM-chitin- or *CM-chitosan- macroradicals formed by eaq- + CM-chitin or CM-chitosan reaction. CM-chitin aqueous solutions were further examined by pulse radiolysis in order to confirm the site of the long-lived radical.
Nuclear Engineering Research Laboratory, School of Engineering, University of Tokyo, Shirakata-Shirane 2-22, Tokai-mura, Naka-gun, Ibaraki-ken, 319-1188 Japan. mlzhai@chem.pku.edu.cn
Maolin
M
Zhai
Hisaaki
H
Kudoh
Guozhong
G
Wu
Radoslaw A
RA
Wach
Yusa
Y
Muroya
Yosuke
Y
Katsumura
Naotsugu
N
Nagasawa
Long
L
Zhao
Fumio
F
Yoshii
D002240:Carbohydrate Sequence; D002686:Chitin / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects*; D004583:Electrons; D005609:Free Radicals / Q000032:analysis / Q000737:chemistry / Q000528:radiation effects; D007834:Lasers; D008969:Molecular Sequence Data; D010782:Photolysis; D012996:Solutions; D014867:Water
D005609:Free Radicals; D012996:Solutions; D014867:Water; D002686:Chitin; C044872:O-(carboxymethyl)chitin