Saccharidnachweis mit Rezeptoren auf Boronsäurebasis

Chiral Binol–Bisboronic Acid as Fluorescence Sensor for Sugar Acids

“…[2,14,15] Binding of l-glycerate by 1 (R or S) was not observed presumably because this substrate lacks a second binding site for bridging. Similarly, the cyclic substrate dglucuronic acid has smaller binding constants than the linear d-glucaric acid.…”

“…The fluorescence enhancement for the complexes formed by either R-or S-1 at pH 8.3 is expected. [2,14,15] Remarkably, at pH 5.6 the fluorescence of S-1 is enhanced by the presence of l-tartaric acid, but for R-1 with the same analyte, the fluorescence is diminished relative to that of the free bisboronic acid. Conversely, the fluorescence of the sensor R-1 is enhanced by the presence of d-tartaric acid, but for S-1 with d-tartaric acid, the fluorescence is diminished relative to that of the free bisboronic acid.…”

“…The fluorescence of the binol moiety can be enantioselectively diminished (via a non-emissive exiplex, or by charge-transfer between the analyte and the sensor), [19][20][21] or enantioselectively enhanced (usually by photoinduced electron transfer (PET)). [2,14,15,19,27,29] However, previous reports of chiral discrimination were based solely on a different extent of the spectral change in a single sense (either enhanced or diminished), [19] rather than on the sense of the change. Fluorescence intensity-pH profiles for titrations with all four saccharides (glucaric acid, gluconic acid, glucuronic acid, and sorbitol) showed that they were bound by R/S-1.…”

“…[19][20][21][22][23][24][25][26][27][28][29][30] In early work, a binol-based bisboronic acid (1) was used to recognize the enantiomers of monosaccharides, such as d/l-glucose, -fructose, and -galactose. [2,14,15] Recently…”

“…[31] The binding constant reported for tartaric acid (1.41 10 3 m À1 at pH 7.77) is comparable to the strengths of interactions with monosaccharides. [2,14,15] Boronic-acid-based fluorescence sensors for tartaric acid, [32] d-glucuronate, [33,34] and d-glucarate [35] have been reported, as has a boronic-acidbased colorimetric indicator-displacement assay for the determination of the enantiomeric excess of a-hydroxy acids. [36] Hydrogen-bonding receptors for the binding of tartaric acid [37] and the chiral discrimination of hydroxy carboxylates [38] and tartaric acid [39,40] are also known.…”