Hydrogen bonds in phenylboronic acids with polyoxaalkyl substituents at ortho-position

Phenylboronic acids with polyoxaalkyl substituents at ortho position were synthesized from the corresponding bromides. Structures in solid state, determined by single crystal X-ray diffraction, reveal the presence of inter- and intramolecular hydrogen bonds. Presence of several oxygen atoms in oxaalkyl chains enables the formation of intramolecular hydrogen bonds by B(OH)2 group with different oxygen centers which lead to the formation of bifurcated hydrogen bonds. Investigated compounds were characterized by 1H, 13C, 11B and 17O NMR spectroscopy in solution. Assignment of 1H and 13C signals was made on the basis of HSQC and HMBC spectra. 17O NMR spectra show that in acetonitrile solution hydrogen bonds with solvent molecules are predominant.