Arbeloa Ernesto Maximiliano, Previtali Carlos Mario, Bertolotti Sonia Graciela
Grupo de Fotoquímica, Departmento de Química, Universidad Nacional de Río Cuarto, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 5800 Río Cuarto, Córdoba, Argentina.
Chemphyschem. 2018 Apr 17;19(8):934-942. doi: 10.1002/cphc.201701295. Epub 2018 Feb 19.
The photophysical and photochemical properties of the xanthene dyes Eosin Y, Erythrosin B, and Rose Bengal are evaluated in the presence of amino-terminated polyamidoamine (PAMAM) dendrimers of relatively high generation (G3-G5) in alkaline aqueous solution. UV/Vis absorption and fluorescence spectra of the dyes show bathochromic shifts, which correlate with the size of the dendrimer. Binding constants (K ) are calculated from absorption data. The resulting high K values indicate strong interactions between both molecules. Triplet-triplet absorption spectra of the dyes are recorded by laser flash photolysis, and a decrease in the triplet lifetimes is observed in the presence of dendrimers. At the same time, an increase in the absorption of the semireduced form of the dyes is observed. Rate constants for triplet quenching ( k ) and radical quantum yields (Φ ) are obtained. The results are explained by a very efficient electron-transfer process from PAMAM to xanthene dyes for all of the dye/dendrimer couples that are evaluated.
在碱性水溶液中，研究了相对高代数（G3 - G5）的氨基端基聚酰胺 - 胺（PAMAM）树枝状大分子存在下，呫吨染料伊红Y、赤藓红B和孟加拉玫瑰红的光物理和光化学性质。染料的紫外/可见吸收光谱和荧光光谱显示出红移，这与树枝状大分子的尺寸相关。结合常数（K）由吸收数据计算得出。所得的高K值表明两种分子之间存在强相互作用。通过激光闪光光解记录染料的三重态 - 三重态吸收光谱，并且在存在树枝状大分子的情况下观察到三重态寿命的降低。同时，观察到染料半还原形式的吸收增加。获得了三重态猝灭速率常数（k）和自由基量子产率（Φ）。对于所有评估的染料/树枝状大分子对，结果可以通过从PAMAM到呫吨染料的非常有效的电子转移过程来解释。
