A Dinuclear Peroxo-Vanadium(V) Complex with Coordinated Tripeptide. Synthesis, Spectra and reactivity in Bromoperoxidation

Abstract

Synthesis of a triglycine peroxo-vanadate complex, [V2O2(O2)3(Gly-Gly-Gly)2].H2O by the reaction of V2O5 with H2O2 and the tripetide at pH 2 is described; the peroxo-bridged complex is highly effective in generating a bromination competent intermediate at physiological pH.

New peroxovanadium compounds containing biogenic co-ligands: synthesis, stability and effect on alkaline phosphatase activity

“…It is pertinent to mention here that maintenance of acidic pH of ca. 3 was one of the essential requirements for the syntheses of a series of peptide containing l-peroxodivanadates synthesized previously by us [18][19][20]. These observations underscore the importance of pH for the successful synthesis of such peroxovanadium compounds, which has also been emphasized in the literature [32,33].…”

“…Although bi or tridentate co-ordination is more common in amino acid or peptide containing complexes [25,[34][35][36][37], monodentate co-ordination through a carboxylate group of the amino acid or peptide zwitterion is not unprecedented [15][16][17][18][19][20]41]. In a structurally characterized monoperoxovanadate compound, isolated from a solution of pH 6.8, glycylglycine was observed to be co-ordinated in a tridentate fashion involving carboxylate, deprotonated N-amide and -NH 2 groups [25].…”

“…The complex species with heptaco-ordinated metal centers exerted strong inhibitory effect on alkaline phosphatase activity [15][16][17]. On the other hand, a series of peptide and amino acid containing peroxo-bridged divanadium compounds, which proved to be powerful oxidants of bromide at near neutral pH, were observed to undergo instant degradation on dissolution [18][19][20].…”

Kinetics of Inhibition of Rabbit Intestine Alkaline Phosphatase by Heteroligand Peroxo Complexes of Vanadium(V) and Tungsten(VI)

“…In the present case, the pH of approximately 5.5 of the reaction medium apparently favored the coordination of triglycine in its zwitterionic form. The observed mode of coordination of triglycine as a bis(ligand) involving O (carboxylate) and O(amide) donor sites in the compounds pV1 and pW1 is not unprecedented [50,52].…”

“…Thus, in the present study, the strategically maintained pH of approximately 5.5 was found to be conducive for the successful synthesis of the desired pV and pW compounds. It is worth mentioning that maintenance of acidic pH of approximately 2.5 was observed to be one of the essential requirements for the synthesis of our previously reported triglycine containing μ-peroxodivanadates, [V 2 O 2 (O 2 ) 3 (triglycine) 2 ]·H 2 O [50]. A peptide molecule is coordinatively versatile and can serve as monodentate, bidentate, or tridentate ligand with different combinations of its donor sites, occurring in complexes in either neutral zwitterionic form or anionic form, depending on the metal ion, pH, and solution composition [40,44,51].…”