Saccharides diboronic acid sensors

The observed stability constants (.Kobs) for 140( =3) 145( =g) divided by the observed stabihty constants (Kobs) of 146(pyrene) are displayed in Figure 35. Overall the diboronic acid sensors retain their selectivity for D-glucose over the other saccharides. 

The observed stability constants ( obs) of sensor 147(phenanthrene pyrene) (with Xex=299 nm and >,ex=342 nm) were calculated by fitting the emission intensities at 417 nm V5. concentration of saccharide curves and are given in Table 5. The observed stability constants (A obs) for the diboronic acid sensor 147(phenanthrene pyrene) ( ex=299 and 342 um) with D-glucose were enhanced relative to those of the monoboronic acid reference compounds 146(pyrene) and 153(phenanthrene)> while the observed stability constants (Aobs) for the diboronic acid sensor... 

Figure 40 Observed stability constants (K hs) of the diboronic acid sensors 148(pyr j-152(2. ap/it/iaiene) divided by the observed stability constants (Kobs) of the corresponding monoboronic acid reference compounds (pyrene) l (phencmthrerte) (2-naphthalerte) iO yield relative ValueS With saccharides. The n-configuration of the monosaccharides was used throughout this evaluation.

James has prepared a ferrocene monoboronic acid 64 and diboronic acid 65 as electrochemical saccharide sensors. The monoboronic acid system 64 has also been prepared and proposed as an electrochemical sensor for saccharides by Norrild and Sotofte. The electrochemical saccharide sensor 65 contains two boronic acid units (saccharide selectivity), one ferrocene unit (electrochemical read out), and a hexamethylene linker unit (for D-glucose selectivity). The electrochemical sensor 65 displays enhanced D-glucose (40 times) and D-galactose (17 times) selectivity when compared to the monoboronic acid 64. 

Shinmori et al. have synthesized a diboronic acid saccharide receptor bearing a photoresponsive azobenzene group, 51 that was used as a light-gated saccharide sensor [119]. When the azobenzene unit is switched by photoirradiation, from the more stable trans-conformation to the thermodynamically unfavorable cis-isomer, it shows high D-glucose and D-allose selectivity. The formation of cyclic 1 1 complexes between saccharide and the dye in its cis-geometry explains the selectivity order. 

Shinmori has synthesised a diboronic acid-saccharide receptor bearing a photoresponsive azobenzene group 161, which was used as a light-gated saccharide sensor. When the azobenzene unit is switched by photoirradiation... 

This book describes the recent efforts to develop practically useful receptors and sensors for saccharides using boronic acids. Since the first publication on glucose-selective diboronic acid-based PET sensors a decade ago, these systems have proved their worth and have come to find application at the cutting edge of medical care. 

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