Structural effect of fluorophore on phenylboronic acid fluorophore/cyclodextrin complex for selective glucose recognition

Based on the design of the fluorescent site of a fluorescent probe, we have created a unique system that changes its twisting response to sugar. Two probes were synthesized, in which phenylboronic acid and two kinds of aromatic fluorescent site (pyrene or anthracene) were conjugated by an amide bond. In the fluorescence measurement of pyrene-type probe 1, dimer fluorescence was observed at high pH. In induced circular dichroism (ICD) experiments, a response was observed only in the presence of glucose and γ-cyclodextrin, and no response was seen with fructose. On the other hand, in the fluorescence measurement of anthracene-type probe 2, dimer fluorescence was observed in the presence of both glucose and galactose, and the fluorescence was different from the case of fructose. When the ICD spectra of these inclusion complexes were measured, an inversion of the Cotton effect, which indicates a change in the twisted structure, was observed in galactose and glucose. These differences in response to monosaccharides may originate in the interaction between the fluorescent site and the cyclodextrin cavity. [Figure not available: see fulltext.]