Determination of Astaxanthin and Canthaxanthin Triplet Properties in Different Polarities of the Solvent by Laser Flash Photolysis

• Published in: Chinese journal of chemistry 2011-07, Vol.29 (7), p.1535-1540
• Main Author: 李海霞 张鹏 宋西玉 王文锋
• Format: Article
• Language: English
• Subjects: astaxanthin; canthaxanthin; energy transfer; laser flash photolysis; photochemistry; 属性; 极性; 测定; 溶剂; 激光闪光光解; 类胡萝卜素; 虾青素; 角黄素
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.201180276

Triplet-triplet extinction coefficients for astaxanthin （I） and canthaxanthin （II） in different deaerated polarity solutions of MeCN and benzene were evaluated by laser flash photolysis at 298 K in the spectral region from 350 to 650 nm by energy transfer method, employing 2-acetonaphthone as sensitizer. The triplet-triplet extinction coeffi- cients in MeCN and benzene were different in terms of the carotenoid present. The maximum triplet-triplet extinc- tion coefficient was 0.1-1.7 ×10^5 L·mol^-1·cm^-1 in different solvents. The rate constants of triplet decay were I： 1.25×10^10 L·mol^-1·s^-1, II： 1.12×10^10 L·mol^-1·s^-1 in MeCN; and I： 1.75×10^10 L·mol^-1, II： 3.27×10^10 L·mol^-1·s^-1 in benzene. The bimolecular rate constants of energy transfer from triplet excited 2-acetonaphthone to carotenoids were determined from the linear regression of the decay rate constant of 2-acetonaphthone triplet at varying carotenoid concentrations. The triplet lifetimes of ^3AST^＊ and 3CAN^＊ in different solvents were also determined. The results indicated that triplet energy transfer was nearly diffusion-controlled.