Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan.
J Photochem Photobiol B. 2009 Dec 2;97(3):132-7. doi: 10.1016/j.jphotobiol.2009.08.010. Epub 2009 Sep 4.
Singlet oxygen ((1)O(2)) quenching by trolox C (TC, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), which is a water-soluble vitamin E analogue, in ethanol-water solutions and in aqueous SDS and CTAC micelles was studied by measuring the time-profiles of (1)O(2) phosphorescence at 1274 nm. The second-order rate-constant for (1)O(2) quenching by TC was determined in the ethanol-water solution to be 1.03 x 10(8), 6.22 x 10(7) and 6.23 x 10(7) M(-1) s(-1) at pH 2.0, 7.0, and 8.4, respectively. These values mean that the non-dissociated form of TC under acidic conditions has superior activity to the mono-anion form. In aqueous micelle systems, the decay rate of (1)O(2) at first decreased and then increased with increase of the concentration of TC. This behavior is explained in terms of the (1)O(2) quenching by TC in the bulk phase and in terms of shifting the environment surrounding (1)O(2) to lipophilic by dissolving TC in the hydrophobic region inside the micelle. The present investigation on (1)O(2) emission dynamics in inhomogeneous solutions made it possible to detect a little change in the solutions, which affects the environment around (1)O(2), such as the micelle formation and dissolving solute in the micelle.
trolox C（6-羟基-2,5,7,8-四甲基色满-2-羧酸，一种水溶性维生素 E 类似物）在乙醇-水溶液以及 SDS 和 CTAC 胶束中的猝灭作用。通过测量 1274nm 处的（1）O2 磷光寿命来研究。在乙醇-水溶液中，确定了 TC 对（1）O2 的二级猝灭速率常数为 1.03 x 10(8)、6.22 x 10(7)和 6.23 x 10(7) M(-1) s(-1)，分别对应 pH 2.0、7.0 和 8.4。这些值意味着在酸性条件下，TC 的非离解形式比单阴离子形式具有更高的活性。在水胶束体系中，（1）O2 的衰减速率最初降低，然后随着 TC 浓度的增加而增加。这种行为可以用 TC 在体相中的（1）O2 猝灭来解释，也可以用 TC 在胶束内部疏水区溶解，从而使（1）O2 周围的环境向亲脂性转移来解释。本研究对非均相溶液中的（1）O2 发射动力学的研究使得可以检测到溶液中稍微的变化，这些变化会影响（1）O2 周围的环境，如胶束的形成和胶束中溶解的溶质。
