Qualitatively Fluorescent Guest-Response of 2^A, 2^x-Disulfonyl Dibenzosulfolane-Diphenyl-Capped β-and γ-Cyclodextrins for Endocrine Disruptors

Abstract

Fluorogenic host capped regioselectively at the lower rim, 2^A, 2^x-disulfonyl dibenzosulfolane-diphenyl capped β-cyclodextrin (X = D for β-1) and γ-cyclodextrins (X = C, D and E for γ-1, γ-2 and γ-3), respectively, have been investigated their fluorescent molecular sensing properties for endocrine disruptors in an aqueous solution. These capping cyclodextrins exhibited monomer fluorescence, in which these hosts fluorescence decreased in intensity on accommodation of endocrine disruptors. The extent of fluorescence variation with a guest was employed to evaluate the sensing abilities of the hosts, using the parameter (ΔI/I⁰) as a sensing factor of the hosts for the guests. Hosts β-1, γ-2 and γ-3 detected phenolic guests such as 3, 4-dichlorophenol, 2, 4, 6-trichlorophenol, p-nonylphenol, and bisphenol A with high sensitivities, and especially, these three hosts exhibited the highest sensitivities for bisphenol A. The sequences of binding of the hosts were γ-3>β-1>γ-2>γ-1 for 3, 4-dichlorophenol and 2, 4, 6-trichlorophenol and β-1>γ-3>γ-2>γ-1 for p-nonylphenol and bisphenol A. The behaviors of the capped units of the hosts during a host-guest complexation were studied by fluorescence spectra and MM2-energy minimized structures. These studies suggest that the capping linker units, which are disulfonyl dibenzosulfolane-diphenyl, work as qualitatively fluorescent probe detecting endocrine disruptors.