Aqueous V(V)-Peroxo-Amino Acid Chemistry. Synthesis, Structural and Spectroscopic Characterization of Unusual Ternary Dinuclear Tetraperoxo Vanadium(V)-Glycine Complexes

Vanadium participation in cellular events entails in-depth comprehension of its soluble and bioavailable forms bearing physiological ligands in aqueous distributions of binary and ternary systems. Poised to understand the ternary V(V)-H2O2-amino acid interactions relevant to that metal ion’s biological role, we have launched synthetic efforts involving the physiological ligands glycine and H2O2. In a pH-specific fashion, V2O5, glycine, and H2O2 reacted and afforded the unusual complexes (H3O)2[V2(O)2(μ2:η2:η1-O2)2(η2-O2)2(C2H5NO2)]·5/4H2O (1) and K2[V2(O)2(μ2:η2:η1-O2)2(η2-O2)2(C2H5NO2)]·H2O (2). 1 crystallizes in the triclinic space group P1̅, with a = 7.805(4) Å, b = 8.134(5) Å, c = 12.010(7) Å, α = 72.298(9)°, β = 72.991(9)°, γ = 64.111(9)°, V = 641.9(6) Å3, and Z = 2. 2 crystallizes in the triclinic space group P1̅, with a = 7.6766(9) Å, b = 7.9534(9) Å, c = 11.7494(13) Å, α = 71.768(2)°, β = 73.233(2)°, γ = 65.660(2)°, V = 610.15(12) Å3, and Z = 2. Both complexes 1 and 2 were characterized by UV/visible, LC-MS, FT-IR, Raman, NMR spectroscopy, cyclic voltammetry, and X-ray crystallography. The structures of 1 and 2 reveal the presence of unusual ternary dinuclear vanadium-tetraperoxo-glycine complexes containing [(VV=O)(O2)2]− units interacting through long V−O bonds and an effective glycinate bridge. The latter ligand is present in the dianionic assembly as a bidentate moiety spanning both V(V) centers in a zwitterionic form. The collective physicochemical properties of the two ternary species 1 and 2 project the chemical role of the low molecular mass biosubstrate glycine in binding V(V)-diperoxo units, thereby stabilizing a dinuclear V(V)-tetraperoxo dianion. Structural comparisons of the anions in 1 and 2 with other known dinuclear V(V)-tetraperoxo binary anionic species provide insight into the chemical reactivity of V(V)-diperoxo species in key cellular events such as insulin mimesis and antitumorigenicity, potentially modulated by the presence of glycinate and hydrogen peroxide.

钒元素在细胞事件中的参与要求深入理解其在二元和三元体系水溶液中的可溶性及生物利用形式的生理配体。为了理解与该金属离子生物学作用相关的三元V(V)-H2O2-氨基酸相互作用，我们启动了涉及生理配体甘氨酸和H2O2的合成研究。在特定的pH条件下，五氧化二钒、甘氨酸和H2O2发生反应，生成了不寻常的配合物（H3O）2[V2(O)2(μ2:η2:η1-O2)2(η2-O2)2(C2H5NO2)]·5/4H2O（1）和K2[V2(O)2(μ2:η2:η1-O2)2(η2-O2)2(C2H5NO2)]·H2O（2）。配合物1以三斜晶系P1̅空间群结晶，其晶胞参数为a = 7.805(4) Å, b = 8.134(5) Å, c = 12.010(7) Å, α = 72.298(9)°, β = 72.991(9)°, γ = 64.111(9)°, V = 641.9(6) Å3, Z = 2。配合物2同样以三斜晶系P1̅空间群结晶，其晶胞参数为a = 7.6766(9) Å, b = 7.9534(9) Å, c = 11.7494(13) Å, α = 71.768(2)°, β = 73.233(2)°, γ = 65.660(2)°, V = 610.15(12) Å3, Z = 2。两种配合物1和2均通过紫外-可见光谱、液相色谱-质谱联用、傅里叶变换红外光谱、拉曼光谱、核磁共振波谱、循环伏安法和X射线单晶衍射等方法进行了表征。1和2的结构揭示了含有[(VV=O)(O2)2]−单元的异常三元二核钒-四过氧甘氨酸配合物的存在，这些单元通过长的V−O键和有效的甘氨酸桥相互作用。后者作为二阴离子组装中的双齿基团，以两性离子的形式跨越两个V(V)中心。两种三元物种1和2的集合物理化学性质预示了低分子量生物底物甘氨酸在结合V(V)-二过氧单元中的作用，从而稳定了二核V(V)-四过氧二阴离子。通过与已知的二核V(V)-四过氧二元阴离子物种的阴离子结构比较，揭示了V(V)-二过氧物种在关键细胞事件如胰岛素模拟和抗癌活性中的化学活性，这些活性可能受到甘氨酸和过氧化氢存在的影响。