Taming fluorescent dyes with cucurbituril

The potential of the supramolecular host molecule cucurbit[7]uril to serve as a stabilizing additive and enhancement agent was investigated for the following dyes in aqueous solution: rhodamine 6G, rhodamine 123, tetramethylrhodamine, cresyl violet, fluorescein, coumarin 102, pyronin B, pyronin Y, two cyanine 5 and one cyanine 3 derivative, and IR140 as well as IR144. For most cationic dyes photostabilization was established, and a pronounced thermal stabilization due to deaggregation and solubilization was observed for the xanthene dyes. The advantageous effects are attributed to the formation of inclusion complexes with different photophysical and photochemical properties. The complexation is accompanied by spectral shifts characteristic for the inclusion in a less polar environment, while the fluorescence quantum yields as well as the brightness show an increase, with few exceptions. As a consequence of the low polarizability inside the cucurbituril cavity, the fluorescence lifetimes of the included dyes increase substantially and systematically. Applications of the new photostabilizing additive for dye lasers, for prolonged storage of dye solutions, in scanning confocal microscopy, and fluorescence correlation spectroscopy are discussed.

研究了超分子主体分子葫芦[7]脲（cucurbit[7]uril）作为稳定添加剂与增强剂，对水溶液中以下染料的作用：罗丹明6G（rhodamine 6G）、罗丹明123（rhodamine 123）、四甲基罗丹明（tetramethylrhodamine）、甲酚紫（cresyl violet）、荧光素（fluorescein）、香豆素102（coumarin 102）、派洛宁B（pyronin B）、派洛宁Y（pyronin Y）、两种氰基5（cyanine 5）衍生物、一种氰基3（cyanine 3）衍生物，以及IR140与IR144。对于大多数阳离子染料，其光稳定性得到验证；而呫吨类染料则因解聚与增溶作用，展现出显著的热稳定性提升。这些有益效应可归因于具有不同光物理及光化学性质的包合物的形成。包合过程伴随特征性光谱位移——这是染料被包合于低极性环境的标志；同时，除少数例外，荧光量子产率与亮度均有所提高。由于葫芦脲空腔内部极化率较低，被包合染料的荧光寿命显著且系统性地延长。此外，本文还探讨了该新型光稳定添加剂在染料激光器、染料溶液长期储存、扫描共聚焦显微镜及荧光相关光谱中的应用。