The design of boronic acid spectroscopic reporter compounds by taking advantage of the pK(a)-lowering effect of diol binding: nitrophenol-based color reporters for diols.
The complex that forms between a boronic acid and a diol is often much more acidic than the starting boronic acid. In conditions where the solution pH is between the two pK(a) values, the boron atom will convert from a neutral trigonal form to an anionic tetrahedral form upon complexation. Such a change is likely to dramatically alter the electron density of neighboring groups. Utilizing this effect, we have designed and synthesized two nitrophenol-based boronic acid reporter compounds that change ionization states and therefore spectroscopic properties upon diol binding. Both compounds show significant UV changes upon addition of saccharides. For example, a blue shift of the absorption max from 373 to 332 nm was observed with the addition of D-fructose to 2-hydroxy-5-nitrophenylboronic acid at neutral pH. Such a reporter compound can be used as a recognition and signaling unit for the construction of polyboronic acid sensors for the selective and specific recognitions of saccharides of biological significance.
Ni
Weijuan
W
Department of Chemistry, North Carolina State University, Raleigh, NC 27695, USA.
Fang
Hao
H
Springsteen
Greg
G
Wang
Binghe
B
D001897:Boronic Acids / Q000138:chemical synthesis*; D002241:Carbohydrates / Q000032:analysis; D003124:Colorimetry; D003517:Cyclopentanes / Q000737:chemistry; D015195:Drug Design; D005632:Fructose / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D006018:Glycols / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D009596:Nitrophenols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods
D001897:Boronic Acids; D002241:Carbohydrates; D003517:Cyclopentanes; D006018:Glycols; D009596:Nitrophenols; D011108:Polymers; C016327:cyclopentanol; D005632:Fructose; D005947:Glucose