Boronic ester of a phthalocyanine precursor with a salicylaldimino moiety

4-(4-Formyl-3-hydroxyphenoxy)phthalonitrile (3) and its condensation product with 2-aminophenol have been synthesized to reach 4-(3-hydroxy-4-(((2-hydroxyphenyl)imino)-methyl)phenoxy)phthalonitrile (5), a tridentate ligand possessing ONO binding sites. Subsequent condensation of phenylboronic acid with 5 afforded a novel boronic ester of a Schiff base with a phthalonitrile group (7). Boronate 7 displays high stability and can be handled in air due to the presence of coordinative B–N and covalent B–O bonds in its structure. The novel compounds were characterized by elemental analyses, IR, UV–vis, mass, 1H-, 13C- and 11B NMR spectra.