SINGLET OXYGEN YIELDS AND RADICAL CONTRIBUTIONS IN THE DYE-SENSITIZED PHOTO-OXIDATION IN METHANOL OF ESTERS OF POLY-UNSATURATED FATTY-ACIDS (OLEIC, LINOLEIC, LINOLENIC AND ARACHIDONIC)
SINGLET OXYGEN YIELDS AND RADICAL CONTRIBUTIONS IN THE DYE-SENSITIZED PHOTO-OXIDATION IN METHANOL OF ESTERS OF POLY-UNSATURATED FATTY-ACIDS (OLEIC, LINOLEIC, LINOLENIC AND ARACHIDONIC)
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DOI：
10.1111/j.1751-1097.1988.tb02760.x
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发表时间：
1988-05-01
影响因子：
3.3
通讯作者：
SINCLAIR, RS
中科院分区：
文献类型：
--
作者：
CHACON, JN;MCLEARIE, J;SINCLAIR, RS
采用激光闪光光解法测定了四种染料敏化剂[亚甲基蓝（MB）、红素（ER）、血卟啉（HP）和核黄素（RF）]在甲醇中的三重态特性（光谱、寿命和量子产率），并通过1270 nm近红外发射时间分辨测量了单重态氧产率（0.60 ~ 0.48）。单线态氧与四个长链不饱和苯基酯[油酸酯（18:1）、亚油酸酯（18:2）、亚麻酸酯（18:3）和花生四烯酸酯（20:4）]的反应采用单线态氧发光技术进行定量跟踪，并在420 ~ 700 nm连续照射后，采用HPLC等方法对同分异构体产物单氢过氧化物进行分析。光氧化的总量子产率(约为。10-2)与观测到的单线态氧猝灭常数（2-12倍）一致。所研究的四种酯在甲醇中的单线态氧寿命为104 dm3 mol-1 s-1。9 .mu.s)。异构体产物的分布是由氧和自由基的双单线态机制来解释的，自由基的贡献在ER .simeq的顺序上随着增敏剂的增加而增加。MB < HP .mchlt。RF，但也显示出一些依赖于衬底不饱和。有证据表明，单重态氧被MB和RF （kQ = 1.6和6.0倍）猝灭。107 dm3 mol-1 s-1)和在不饱和酯存在下染料敏化剂的加速光漂白。
The triplet state characteristics (spectrum, lifetime and quantum yield) for four dye sensitizers [methylene blue (MB), erythrosin (ER), haematoporphyrin (HP) and riboflavin (RF)] were determined in methanol by laser flash photolysis and singlet oxygen yields (0.60 to 0.48) from time-resolved measurements of the 1270 nm near infrared emission. The reaction of singlet oxygen with four long chain unsaturated phenyl esters [oleate (18:1), linoleate (18:2), linolenate (18:3) and arachidonate (20:4)] was followed quantitatively using the singlet oxygen luminescence technique and also, after continuous 420-700 nm irradiation, by HPLC and other analysis of the isomeric product monohydroperoxides. The overall quantum yield of photooxidation (.apprx. 10-2) was shown to be consistent with the observed singlet oxygen quenching constants (2-12 .times. 104 dm3 mol-1 s-1) for the four esters studied and the singlet oxygen lifetime in methanol (.tau. .apprx. 9 .mu.s). The isomer product distribution was interpreted in terms of a dual singlet oxygen and radical mechanism, the radical contribution increasing with sensitizer in the order ER .simeq. MB < HP .mchlt. RF, but also showing some dependence on substrate unsaturation. Evidence is presented for singlet oxygen quenching by MB and RF (kQ = 1.6 and 6.0 .times. 107 dm3 mol-1 s-1) and for the accelerated photobleaching of the dye sensitisers in the presence of the unsaturated esters.