Abstract
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.