Departamento de Química, Universidad Nacional de Río Cuarto, 5800 Río Cuarto, Argentina.
Photochem Photobiol Sci. 2018 May 16;17(5):652-659. doi: 10.1039/c8pp00039e.
The interaction of the singlet and triplet excited states of the synthetic dye safranine-O with carboxyl-terminated poly(amidoamine) (PAMAM) dendrimers was investigated in a buffer solution at pH 8. Low half-generation PAMAM dendrimers (G -0.5; G +0.5: G 1.5) were employed. The UV-vis absorption spectrum of the dye presents only a very small red shift in the presence of dendrimers. Fluorescence quenching was detected and it was interpreted by a static mechanism in terms of the association of the dye with the dendrimer. Laser flash photolysis experiments were carried out and transient absorption spectra of the triplet and radicals were obtained. The triplet state is quenched by the dendrimers with rate constants well below the diffusional limit. The quenching process was characterized as an electron transfer process and the quantum yield of radicals was estimated. It was found that radicals are formed with a high efficiency in the triplet quenching reaction.
在 pH 值为 8 的缓冲溶液中研究了合成染料藏红 O 的单重态和三重态与羧基封端的聚（酰胺-胺）（PAMAM）树枝状大分子的相互作用。研究使用了低代半代 PAMAM 树枝状大分子（G-0.5；G+0.5：G1.5）。染料的紫外可见吸收光谱在存在树枝状大分子时仅表现出非常小的红移。检测到荧光猝灭，并根据染料与树枝状大分子的缔合，通过静态机制进行了解释。进行了激光闪光光解实验，并获得了三重态和自由基的瞬态吸收光谱。三重态被树枝状大分子猝灭，速率常数远低于扩散极限。猝灭过程被表征为电子转移过程，并估计了自由基的量子产率。发现自由基在三重态猝灭反应中以高效率形成。
