A new boronic acid fluorescent sensor based on fluorene for monosaccharides at physiological pH

• A new fluorene based fluorescent sensor for monosaccharides is introduced.
• It has high affinity (Ka = 3582.88 M−1) and selectivity for fructose.
• The interaction between 7-DMAFBA and some other saccharides were also studied.
• pH induced fluorescent changes in the absence and presence of fructose were studied.

Fluorescent boronic acids are very useful fluorescent sensor for detection of biologically important saccharides. Herein we synthesized a new fluorene-based fluorescent boronic acid that shows significant fluorescence changes upon addition of saccharides at physiological pH. Upon addition of fructose, sorbitol, glucose, galactose, ribose, and maltose at different concentration to the solution of 7-(dimethylamino)-9,9-dimethyl-9H-fluoren-2-yl-2-boronic acid (7-DMAFBA, 1), significant decreases in fluorescent intensity were observed. It was found that this boronic acid has high affinity (Ka = 3582.88 M−1) and selectivity for fructose over glucose at pH = 7.4. The sensor 1 showed a linear response toward d-fructose in the concentrations ranging from 2.5 × 10–5 to 4 × 10–4 mol L−1 with the detection limit of 1.3 × 10–5 mol L−1.

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