Influence of the ortho-methoxyalkyl substituent on the properties of phenylboronic acids

Novel phenylboronic acids with methoxyalkyl groups at ortho position were synthesized. Molecular and crystal structures for two compounds were determined by single crystal X-ray diffraction. In both cases the O–H⋯O hydrogen-bonded dimers are the primary supramolecular motives in which the relatively short intramolecular B–O–H⋯O hydrogen bonds are observed between boronic group and oxygen atom of the ortho-substituent. Based on the CSD data for ortho-substitued boronic acids, the relation between the twist of the boronic moiety towards phenyl ring and the intramolecular H-bond angle is discussed. The intermolecular interactions between dimeric motives were investigated with the aid of Hirshfeld surface analysis. The weak C–H⋯O and C–H⋯π interactions were detected together with the agostic B⋯H ones. Sugar-binding ability of the methoxyalkyl compounds was evaluated for d-glucose, d-fructose and d-galactose by the competition assay with Alizarin Red S.