Vanadium(IV)-citrate complex interconversions in aqueous solutions. A pH-dependent synthetic, structural, spectroscopic, and magnetic study.

摘要: Citrate is abundantly encountered in biological fluids as a natural metal ion chelator. Vanadium participates processes catalyst the active sites of metalloenzymes, metabolic regulator, mitogenic activator, and an insulin-mimicking agent. Thus, vanadium chemistry with chelators, such citrate, may have immediate implications on its role cellular milieu, action In effort to comprehend aqueous one vanadium's oxidation states, namely, V(IV), implicated activity, reactions VCl(3) citric acid were pursued water led V(IV)-citrate complexes, nature properties which depend strongly solution pH. Analytical, FT-IR, UV/vis, EPR, magnetic susceptibility data supported formulation X(4)[[VO(H(-1)Cit)](2)] x nH(2)O (H(-1)Cit = C(6)H(4)O(7)(4-); X K(+), n 6 (1); Na(+), 12 (2); NH(4)(+), 2 (3)) (pH approximately 8) X(3)[[V(2)O(2)(H(-1)Cit)(Cit)]] (X 7 (4)) 5). Complex crystallizes space group P2(1)/c, 11.3335(9) A, b 15.788(1) c 8.6960(6) beta 104.874(3) degrees, V 1503.8(2), Z 2. 3 P macro, 9.405(1) 10.007(1) 13.983(2) alpha 76.358(4) 84.056(4) gamma 66.102(4) 1169.2(3), 4 P2(1)nb, 9.679(4) 19.618(8) 28.30(1) 5374.0(4), 8. The X-ray structures 1-4 are V(2)O(2) dimers, citrate displaying varying coordination numbers modes. 1 exhibits small ferromagnetic interaction, whereas antiferromagnetic interaction between V(IV) ions. interconvert pH, thus rendering pH determining factor promoting variable structural, electronic, species. observed behavior consistent past speciation studies, contributes understanding significant aspects biologically relevant vanadium(IV)-citrate chemistry.