Phenyl boronic acid complexes of diols and hydroxyacids

Abstract

Abstract:Cumulative formation constants for the interaction of phenylboronic acids with 1,2-diols and structurally related α-hydroxy carboxylic acids were determined by potentiometric titration in aqueous solution. Although there is a significant electronic effect on the acidity of phenylboronic acid (ρ = 2.1), there is no marked electronic effect on the stability of the complexes. Rather, the complexes are significantly destabilized by adjacent anionic groups, by steric interactions across the face of the cyclic boronate ester, and by angle strain within the boronate ester ring. Binding that is nearly independent of pH is observed for some favorably constituted α-hydroxy acid complexes as a result of the relatively high acidity of the acids, which in turn allows tetrahedral boronate complexes to persist in acidic solution (pH < 3).

Dopamine/2-Phenylethylamine Sensitivity of Ion-Selective Electrodes Based on Bifunctional-Symmetrical Boron Receptors

“…The observed relation is a consequence of the boron Lewis acidity and the rigidity of the boronic group. OPBA, being the weakest Lewis acid in the studied series (with p K a of about 9.5 [65]), weakly interacts with amines. In turn, the PBPA molecule represents the Wulf-type receptor with two relatively strong intramolecular OH–N hydrogen bonds, found both in the theoretically optimized molecule and crystal structures of this compound [34].…”

Cation exchange/hydrophobic interaction monolithic chromatography of small molecules and proteins by nano liquid chromatography†

“…Phenyl boronic acid is a weak acid with p K a of 8.66. Because the boron atom in VPBA has tetrahedral sp 3 orbital hybridization status, the boron is negatively charged in basic conditions . The general ionization formula is given in Scheme .…”

Boronic esters of a porphyrazine and its precursor

“…The reversible nature of boronic acid complexation with diols makes this type of interaction highly suitable for the reversible self-assembly of multicomponent systems [7,8]. With these types of reversible systems any errors that occur during the assembly process may be corrected because equilibration of the reactive species results in formation of a thermodynamically favored product [9].…”