Controlled one pot synthesis of polyoxofluorovanadate molecular hybrids exhibiting peroxidase like activity

Abstract

Three unique mixed-valence polyoxofluorovanadate clusters have been synthesized through a facile preparation process. The structure of these clusters is controlled by the addition of organic ligands. Single-crystal X-ray diffraction revealed that the clusters have the formula (XyH₂)₄[V^V₁₀V^IV₄O₁₄(μ-O)₁₀(μ₃-O)₁₀(μ₃-F)₂F₄] (1), (Xy = m-xylylenediamine), (pyH)₄(H)₂[V^V₁₀V^IV₂O₁₂(μ-O)₈(μ₃-O)₁₀(μ₃-F)₂(pic)₂] (2) and (pyH)₄(H)₃(Na⁺)[V^V₇V^IV₂O₉(μ-O)₈(μ₃-O)₄(μ₅-F)(pic)₄]₂ (3), (py = pyridine, pic⁻ = picolinate), with 2 and 3 representing the first examples of polyoxofluorovanadate clusters coordinated to a chelating ligand. The electron paramagnetic resonance (EPR) spectroscopy of 1 revealed that the spins of the V^IV centers are coupled to each other, in contrast to the isolated spins of the isostructural [V^V₁₂V^IV₂O₁₆(μ-O)₁₀(μ₃-O)₁₀(μ₃-F)₂(L)₂]⁶⁻, where L: im = imidazole (4); py (5). The trigonal bipyramidal coordinated V^V atoms of 1, 4 and 5 mimic the structure of the active site of the vanadium dependent peroxidases and 4 and 5 exhibit peroxidase like activity.