Fluorene-based boronic acids as fluorescent chemosensor for monosaccharides at physiological pH.

Two fluorene-based boronic acids, 9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (1) and 9,9-dimethyl-9H-fluoren-2,7-diyl-2,7-diboronic acid (2), were synthesized and their sensing abilities for detection of D-monosaccharides were investigated by fluorescence at physiological pH. It was found that both boronic acids 1 and 2 have high selectivity and sensitivity for D-fructose with stability constant of 47.2 and 412.9, respectively. The sensor 2 showed a linear response toward D-fructose in the concentration range from 5 × 10(-5) to 10(-1) mol L(-1) with the detection limit of 2 × 10(-5) mol L(-1).