Complexation and Fluorescence of Tricyclic Basic Dyes Encapsulated in Cucurbiturils

✍ Scribed by Pedro Montes-Navajas; Avelino Corma; Hermenegildo Garcia

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 349 KB
• Volume: 9
• Category: Article
• ISSN: 1439-4235
• DOI: 10.1002/cphc.200700735

✦ Synopsis

Abstract

Tricyclic basic dyes (proflavine, acridine orange, pyronine, pyronine Y, oxonine, thionine and methylene blue) often form one‐to‐one or two‐to‐one complexes with CB[7] and CB[8], respectively. In the case of pyronine Y, the complexes with CB[7] and CB[8] have a one‐to‐one and three‐to‐one stoichiometry, respectively. The binding constants for CB[7] complexes range from 3.07×10^6^ to 1.70×10^7^ m^−1^. In the case of CB[8], the association constant varies between 3.24×10^13^ and 2.50×10^16^ m^−2^. Overall, these binding constants are four orders of magnitude higher than those reported for the same dyes in β and γ‐cyclodextrins. Formation of the host–guest complexes leads to an increase in the fluorescence quantum yields in the case of CB[7], while the dimeric or trimeric dye encapsulated in CB[8] are remarkably less fluorescent than the same dye in diluted solutions.