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.