title: New synthetic strategies for xanthene-dye-appended cyclodextrins.
abstract: Xanthene dyes can be appended to cyclodextrins via an ester or amide bridge in order to switch the fluorescence on or off. This is made possible through the formation of nonfluorescent lactones or lactams as the fluorophore can reversibly cyclize. In this context we report a green approach for the synthesis of switchable xanthene-dye-appended cyclodextrins based on the coupling agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). By using 6-monoamino-β-cyclodextrin and commercially available inexpensive dyes, we prepared rhodamine- and fluorescein-appended cyclodextrins. The compounds were characterized by NMR and IR spectroscopy and MS spectrometry, their UV-vis spectra were recorded at various pH, and their purity was determined by capillary electrophoresis. Two potential models for the supramolecular assembly of the xanthene-dye-appended cyclodextrins were developed based on the set of data collected by the extensive NMR characterization.
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd., Budapest, H-1097 Illatos út 7, Hungary.
authors.forename: Milo
authors.initials: M
authors.lastname: Malanga
authors.affiliation: Department of Pharmacognosy, Semmelweis University, H-1085 Üllői út 26, Hungary.
authors.forename: Andras
authors.initials: A
authors.lastname: Darcsi
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd., Budapest, H-1097 Illatos út 7, Hungary.
authors.forename: Mihaly
authors.initials: M
authors.lastname: Balint
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd., Budapest, H-1097 Illatos út 7, Hungary; Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 12843 Prague 2, Czech Republic.
authors.forename: Gabor
authors.initials: G
authors.lastname: Benkovics
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd., Budapest, H-1097 Illatos út 7, Hungary.
authors.forename: Tamas
authors.initials: T
authors.lastname: Sohajda
authors.affiliation: Department of Pharmacognosy, Semmelweis University, H-1085 Üllői út 26, Hungary.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Beni
keywords: DMT-MM; fluorescein; rhodamine; supramolecular assembly