Abstract
Flexible hosts, regioselectively hetero-labeled 6A-anthranilate-6X-O-p-tosyl-labeled β-cyclodextrins (X=B or G, C or F, and D or E for β-1, β-2, and β-3, respectively), have been synthesized to investigatetheir chemo-sensor potential as host compounds for biochemical substances such as bile acids and terpenoidsas guest molecules. These hosts showed pure monomer fluorescence, exhibiting increase in fluorescence intensityon complexation of the all guests examined. The extent of the fluorescence variation with a guest wasemployed to evaluate the sensing abilities of these hosts, and the sensing parameter (ΔI/I0) was used to describethe sensing abilities of the hosts. Hosts β-2 and β-3 recognized bile acids with high sensitivity, whereas β-1 detected all guests examined with low sensitivity. On the whole, the sequence of the bindingability of these hosts was β-3>β-2>β-1 for bile acids. The behaviors of the appended units of these hostsduring a formation of the host-guest complexation were studied by induced circular dichroism (ICD) andfluorescence spectra. The ICD spectra of these hosts showed same patterns. The guest-induced variations in ICD and fluorescence spectra suggest that anthranilate and tosyl units take movement with a changing theirmutual relationship in the place to work as spacers. The parameter values of the titled hosts are much higherthan those of homo-labeled anthranilate β-cyclodextrin analogs.
