Photochemical studies of 4-tert-butyl-4′-methoxydibenzoylmethane (BM-DBM)

被引：81

作者：

Cantrell, A ^{[1
]}

McGarvey, DJ ^{[1
]}

机构：

[1] Univ Keele, Leonard Jones Labs, Sch Chem & Phys, Keele ST5 5BG, Staffs, England

来源：

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY | 2001年 / 64卷 / 2-3期

关键词：

sunscreens; BM-DBM; dibenzoylmethane; triplet states; triplet quenching; photodegradation;

D O I：

10.1016/S1011-1344(01)00226-3

中图分类号：

Q5 [生物化学]; Q7 [分子生物学];

学科分类号：

071010 ; 081704 ;

摘要：

Kinetic UV-VIS absorption data following 355 and 266 nm nanosecond laser flash photolysis of 4-tert-butyl-4'-methoxydibenzoylmethane (BM-DBM) solutions is presented. The kinetics of the decay of the non-chelated enol (NCE) produced following 355 nm excitation of BM-DBM solutions are analysed in terms of mixed 1st- and 2nd-order kinetics. The temperature dependences of the component rate constants are unusual and both 1st- and 2nd-order components display negative activation energies, which are explained by invoking pre-equilibria. In addition, it is shown for the first time that 266 nm laser photolysis of BM-DBM solutions leads to formation of the triplet state of the keto (K) form with a lifetime of similar to 500 ns. Under these conditions the triplet state of the K form is quenched by oxygen. (C) 2001 Elsevier Science B.V. All rights reserved.

引用

页码：117 / 122

页数：6

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