title: Exploiting the reversible covalent bonding of boronic acids: recognition, sensing, and assembly.
abstract: Boronic acids can interact with Lewis bases to generate boronate anions, and they can also bind with diol units to form cyclic boronate esters. Boronic acid based receptor designs originated when Lorand and Edwards used the pH drop observed upon the addition of saccharides to boronic acids to determine their association constants. The inherent acidity of the boronic acid is enhanced when 1,2-, 1,3-, or 1,4-diols react with boronic acids to form cyclic boronic esters (5, 6, or 7 membered rings) in aqueous media, and these interactions form the cornerstone of diol-based receptors used in the construction of sensors and separation systems.  In addition, the recognition of saccharides through boronic acid complex (or boronic ester) formation often relies on an interaction between a Lewis acidic boronic acid and a Lewis base (proximal tertiary amine or anion). These properties of boronic acids have led to them being exploited in sensing and separation systems for anions (Lewis bases) and saccharides (diols).  The fast and stable bond formation between boronic acids and diols to form boronate esters can serve as the basis for forming reversible molecular assemblies. In spite of the stability of the boronate esters' covalent B-O bonds, their formation is reversible under certain conditions or under the action of certain external stimuli.  The reversibility of boronate ester formation and Lewis acid-base interactions has also resulted in the development and use of boronic acids within multicomponent systems. The dynamic covalent functionality of boronic acids with structure-directing potential has led researchers to develop a variety of self-organizing systems including macrocycles, cages, capsules, and polymers.  This Account gives an overview of research published about boronic acids over the last 5 years. We hope that this Account will inspire others to continue the work on boronic acids and reversible covalent chemistry.
authors.affiliation: Department of Chemistry, University of Bath, Bath BA2 7AY UK.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Bull
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Davidson
authors.forename: Jean M H
authors.initials: JM
authors.lastname: van den Elsen
authors.forename: John S
authors.initials: JS
authors.lastname: Fossey
authors.forename: A Toby A
authors.initials: AT
authors.lastname: Jenkins
authors.forename: Yun-Bao
authors.initials: YB
authors.lastname: Jiang
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kubo
authors.forename: Frank
authors.initials: F
authors.lastname: Marken
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakurai
authors.forename: Jianzhang
authors.initials: J
authors.lastname: Zhao
authors.forename: Tony D
authors.initials: TD
authors.lastname: James
mesh_terms: D001897:Boronic Acids / Q000737:chemistry*; D003500:Cyclization; D004298:Dopamine / Q000737:chemistry; D004586:Electrophoresis; D004952:Esters / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction
chemical_list: D001897:Boronic Acids; D004952:Esters; D005456:Fluorescent Dyes; D004298:Dopamine