Selective Fluorescent Molecular Sensing Based on 2A,2D-Disulfonyl Dibenzosulfolane-diphenyl-capped β-Cyclodextrin for Phenolic Guests

Abstract

Cyclodextrins (CyDs), which are torus-shaped cyclic oligomers composed of D-glucopyranose, are named α-, β-and γ-for the hexamer, heptamer and octamer, respectively. CyDs form inclusion complexes with various organic guests in an aqueous solution. 1 Recently, chromophore-modified CyDs have been shown to exhibit remarkable variations in circular dichroism, absorption and fluorescence spectra, depending on the formation of host-guest complexation; 2-6 therefore, the appended chromophores can be used as a probe to sense guest molecules. Previously, we have discussed fluorescence molecular sensing systems of CyDs modified with fluorescent active units at the upper rim. [7][8][9][10][11][12] In these systems, it was found that the fluorescence spectra are most sensitively observed in spectrophotometry, in which variations of guest-induced fluorescence intensities effectively work as a sensing probe, showing much more complete and accurate sensing patterns. In contrast, there are several papers which describe the fluorescent binding property of CyD derivatives substituted at the lower rim (C-2 or C-3 positions) and the difficulties to sulfonate the secondary hydroxyl group. [13][14][15][16][17] However, Teranishi has prepared mono-and regioselectively di-sulfonyl β-and γ-CyDs at the lower rim (C-2 position) from sulfonyl imidazole treated with molecular sieves 4A under mild condition. [18][19][20][21] These new modifications produced CyDs at the lower rim which are very interesting. During the last year, we discussed a selective fluorescent sensing system of CyDs modified with pyrene and tosyl at the lower and upper rims, respectively, 22 in which the pyrene moiety at the lower rim of CyD worked as a more sensitive fluorescent probe to distinguish the structures of steroidal compounds. For a further extension of our work, we tried to study the fluorescent molecular sensing abilities for endocrine disruptors based on β-CyD capping at the lower rim, which is 2 A ,2 D -disulfonyl dibenzosulfolane-diphenyl capped β-CyD (β-1), 23 in an aqueous solution. A couple of fluorescent capped CyDs at the upper rim have been reported that shows a low molecular sensing ability due to a difficulty to move these fluorescent linker. 3,24 However, the host β-1, which is the first example of a regioselectively capped CyD at the lower rim, can peculiarly recognize phenolic guests, such as p-nonylphenol and bisphenol A. Experimental MeasurementsFluorescence spectra were measured at 25˚C using a PerkinElmer LS 40B fluorescence spectrometer. The excitation wavelength was 330 nm, and the excitation and emission slits were 4 nm. Five microliters of guest species (0.5, 0.05 and 0.005 M) in MeOH or dimethyl sulfoxide (DMSO) were injected into a 10 vol.% ethylene glycol aqueous solution of β-1 (2.5 mL, 1.0 × 10 -6 M). This procedure gave a guest concentration of 1.0, 0.1 and 0.01, respectively, in the sample solution. Energy-minimized structuresEnergy-minimized structures were calculated by molecular mechanics using MM2 in CS Chem 3D. The paramete...

Laser Spectroscopy for Atmospheric and Environmental Sensing

“…Despite the thorough nature of this review, only a limited number of topics relevant to PL-based sensing have been covered. Due to time and space limitations, the review of totally organic-based VOC sensing compounds such as luminescent β–cyclodextrins [380-393] was omitted. Also, recent reports on PL-based microarrays and artificial noses [394-400] were not discussed in detail.…”

Structural investigations of pyridin-4-yl indolizine modified β-cyclodextrin derivatives as fluorescent chemosensors for organic guest molecules

“…1 Cyclodextrins being essentially inert to photochemical excitation, their chemical modification with chromophoric entities can allow to associate spectroscopic properties to the inclusion of guest molecules. [2][3][4][5][6][7][8][9][10][11][12] Thus, modified CDs bearing fluorophores such as dansyl 3 and p-(dimethylamino)-benzoyl (DMAB) moieties 4 are examples of sensoring systems with which spectroscopically inert organic molecules could be detected by variations in their emissions spectra in aqueous solution.…”