Macromolecular peroxo complexes of Vanadium(V) and Molybdenum(VI): Catalytic activities and biochemical relevance

Abstract

Our recent achievements concerning the synthesis and characterization of water soluble peroxo complexes of V(V) and Mo(VI) in macroligand environment, as well as some key features of biological relevance of these compounds, such as their hydrolytic stability, activity with phosphohydrolase enzyme vis-à-vis free peroxovanadium (pV) or peroxomolybdenum (pMo) complexes, and their activity in biomimetic oxidative bromination are presented here. Immobilization of pMo species on insoluble polymer matrices viz., amino acid functionalized Merrifield resins and poly(acrylonitrile) on the other hand, afforded a set of heterogeneous catalysts highly effective in facile organic transformations such as selective oxidation of organic sulfides and oxidative bromination of aromatic substrates by H 2 O 2 , at ambient temperature. The methodologies are straightforward, high-yielding, halogen-free and the catalysts afford easy regeneration. Our findings illustrate the various features which make the procedures sustainable and synthetically useful.

Peroxo Compounds of Vanadium(V) and Niobium(V) as Potent Inhibitors of Calcineurin Activity towards RII‐Phosphopeptide

“…The ligand environment of the complexes did not appear to have significant effect on the inhibitor efficiency of the compounds. This observation is in contrast to our previous findings with respect to inhibition of ACP and ALP by peroxometallates, where the nature of the ligand sphere of the inhibitors showed a marked influence on the extent as well as mode of inhibition of these enzyme functions ,,,…”

“…Moreover, the macromolecular peroxometallate synthesized by us, were found to be potent inhibitors of phosphohydrolase enzymes viz ., acid and alkaline phosphatases ,. Our detailed investigation on inhibition kinetics involving a variety of peroxo complexes of V, Mo and W revealed for the first time that polymer anchored and free monomeric peroxo compounds induce their inhibitory effects on alkaline (ALP) as well as acid phosphatases (ACP) through distinct pathways ,,,. In a recent comprehensive review, Crans et al .…”

“…Majority of the synthetic peroxovanadates have however limited clinical potential due to their long‐term stability issues and toxic effects ,. It is notable that, in our previous work we have synthesized series of stable and structurally defined peroxo complexes of the metals viz ., V, Mo and W, supported on functionalized water soluble polymers (WSP) . Usefulness of linear WSPs, which are essentially polychelatogens, as supports in diverse fields of chemistry and biology are increasingly being realized in recent years .…”

“…[32,[34][35][36][37] It is notable that, in our previous work we have synthesized series of stable and structurally defined peroxo complexes of the metals viz., V, Mo and W, supported on functionalized water soluble polymers (WSP). [38][39][40][41][42] Usefulness of linear WSPs, which are essentially polychelatogens, as supports in diverse fields of chemistry and biology are increasingly being realized in recent years. [43][44][45][46][47] These systems are often free from issues related to undesirable attributes such as toxicity, volatility, lability and odor.…”

“…[39,40] Our detailed investigation on inhibition kinetics involving a variety of peroxo complexes of V, Mo and W revealed for the first time that polymer anchored and free monomeric peroxo compounds induce their inhibitory effects on alkaline (ALP) as well as acid phosphatases (ACP) through distinct pathways. [39][40][41]49,51,52] In a recent comprehensive review, Crans et al [53] observed that despite the existence of many studies on phosphatase inhibition by vanadate and related compounds where relative inhibitory potency such as EC 50 values have been measured, reports dealing with mechanism of such inhibition supported by kinetic data with defined K i values are still very few.…”