Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
J Phys Chem B. 2011 Aug 11;115(31):9576-84. doi: 10.1021/jp200126f. Epub 2011 Jul 18.
Cyanine-3 (Cy3) fluorescent dye molecules confined in sodium di-2-ethylhexyl sulfosuccinate (AOT) reverse micelles were examined using steady-state absorption and emission as well as time-resolved fluorescence spectroscopy to understand the effect of confinement on the spectroscopic properties of the dye. This study explored a wide range of reverse micelle sizes, with hydrodynamic radii ranging from ∼1.7 to ∼5 nm. The relative concentrations of Cy3 and AOT reverse micelles were such that, on average, one dye molecule was present for every 2 × 10(4) to 9 × 10(5) reverse micelles. In the smallest reverse micelles examined, observed changes in the absorption and emission spectra and fluorescence lifetime of the dye molecules indicated H-aggregation of Cy3 into side-by-side dimers. It is hypothesized that this dimerization is governed by the high local concentrations that result from the confinement of the Cy3 in the reverse micelles. What is notable about this study is that this dimer occurs even at overall dye concentrations in the nanomolar range. Such concentrations are too low for aggregation to occur in bulk solution. Hence, the reverse micelles serve as nanocatalysts for this aggregation process.
用稳态吸收和发射以及时间分辨荧光光谱法研究了束缚在磺基琥珀酸二（2-乙基己基）酯（AOT）反胶束中的菁染料 3（Cy3）荧光染料分子，以了解约束对染料光谱性质的影响。本研究考察了广泛的反胶束尺寸范围，水动力学半径从约 1.7nm 到约 5nm。Cy3 和 AOT 反胶束的相对浓度使得，平均而言，每 2×10(4)到 9×10(5)个反胶束中存在一个染料分子。在研究的最小反胶束中，观察到染料分子的吸收和发射光谱以及荧光寿命的变化表明 Cy3 发生了 H-聚集，形成了并排二聚体。据推测，这种二聚化是由 Cy3 在反胶束中的约束导致的局部高浓度所控制的。这项研究的显著之处在于，即使在整体染料浓度处于纳摩尔范围内，也会发生这种二聚体。这种浓度太低，不会在体相溶液中发生聚集。因此，反胶束是这种聚集过程的纳米催化剂。
