Transition metal complexes of new glyoxylato-aroylhydrazones and their role in l-ascorbic acid oxidation inhibition

We report here the synthesis of new ligands of the aroylhydrazone family. Glyoxylato-aroylhydrazones (gly-AH) with lipophilic character were designed for possible biological applications where metal chelation is desired. They were found to coordinate readily with a number of metals and the crystal structures of the copper and zinc complexes, M(py)2L (M = Cu, Zn); LH2 (L2) = N′-(2-hydroxy-3-(pentan-3-yl)benzylidene)-2-mesityl-2-oxoacetohydrazide have been determined. The complexes both display a distorted trigonal bipyramidal coordination geometry around the metals. Ascorbate oxidase and ascorbate peroxidase mimicking reactions were carried out to determine the ability of the title ligands to inhibit metal-induced oxidation of l-ascorbic acid via complexes generated in situ.

We report here the synthesis of new ligands of the aroylhydrazone family. Glyoxylato-aroylhydrazones (gly-AH) with lipophilic character were designed for possible biological applications where metal chelation is desired. They were found to coordinate readily with a number of metals and the crystal structures of the copper and zinc complexes, M(py)2L (M = Cu, Zn); LH2 (L2) = N′-(2-hydroxy-3-(pentan-3-yl)benzylidene)-2-mesityl-2-oxoacetohydrazide have been determined. The complexes both display a distorted trigonal bipyramidal coordination geometry around the metals. Ascorbate oxidase and ascorbate peroxidase mimicking reactions were carried out to determine the ability of the title ligands to inhibit metal-induced oxidation of l-ascorbic acid via complexes generated in situ.Figure optionsDownload as PowerPoint slideHighlights
► Novel complexes with glyoxylato-aroylhydrazones have been synthesised.
► X-ray crystal structure determinations have elucidated the coordination behavior of the new ligands.
► The inhibitory effects of the new ligands on ascorbic acid oxidation were studied.