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Studies on the Coordination Chemistry of Vanadium, Barium and Cobalamins

Mukherjee, Riya

Abstract Details

2011, PHD, Kent State University, College of Arts and Sciences / Department of Chemistry.

Part 1 of this dissertation concerns studies on polynuclear V(III)/carboxylato complexes (Chapter 2) and a Ba(II)/thiodiacetato complex (Chapter 3) formed in aqueous solution. The structures of[V3(µ3-O)(µ-OOCCH2Br)6(OH2)3]CF3SO3•H2O and [V3(µ3-O)(µ-OOCCH2CH3)6(OH2)3]Cl•2H2O have been determined by X-ray diffraction in chapter 2. Electrospray mass spectrometry, 1H NMR and UV-vis spectroscopy and diffusion coefficient measurements suggest that trinuclear and tetranuclear V(III)/carboxylato complexes are present in solution. Chapter 3 concerns the synthesis of polymeric {Ba[S(CH2COO)2(H2O)3]•2H2O}n, characterized by X-ray diffraction, elemental analysis, FT-IR spectroscopy, thermogravimetric analysis and 1H and 13C NMR spectroscopy. Ba2+ is ten-coordinate, ligated to four tda (O and S) and three aqua ligands. Bridging of Ba2+ centers via the tda ligand creates an extended 2-D polymeric layered structure. Part 2 of this dissertation is concerned with cobalamin (= vitamin B12) chemistry. The development of vanadate (V(V)) therapeutics as oral insulin enhancing agents substitutes for treating diabetes is an active research field. By coordinating the therapeutic to the β axial site of cobalamin, the absorption and cellular uptake is significantly enhanced. In Chapter 4, the extensive solution characterization of two vanadate/B12 conjugates incorporating a (3-hydroxy-2-methyl-1H-pyridin-4-one)propyl linker is reported. The conjugates are tested in the streptozotocin rat model for Type 1 diabetes.

The orally administered therapeutic captopril is widely used for treating hypertension and cardiovascular disease, with undesirable side effects. Chapter 5 reports the synthesis of captoprilcobalamin (CapSCbl). Characterization by 1H NMR spectroscopy and X-ray diffraction shows that CapSCbl exists as two geometric isomers. Kinetic studies on the formation of CapSCbl and its decomposition in acidic solution are also reported.

The last two chapters report rate constants and proposed mechanisms for the reactions of peroxynitrite/peroxynitrous acid (ONOO-/ONOOH) with the reduced forms of vitamin B12, cob(II)alamin (Chapter 6) and cob(I)alamin (Chapter 7). ONOO-/ONOOH is implicated in multiple inflammatory and neurodegenerative diseases. ONOOH reacts directly with Cb(II) to give cob(III)alamin and •NO2, followed by a rapid reaction between •NO2 and Cbl(II) to primarily form nitrocobalamin. A mechanism involving rate-determining 1e- oxidation of Cbl(I) by ONOO(H) to yield Cbl(I) and •NO2 followed by multiple fast steps leading ultimately to oxidation of 5Cbl(I) to 5Cbl(II) and N2 formation is proposed.

Nicola E. Brasch, Ph.D. (Advisor)
264 p.

Recommended Citations

Citations

  • Mukherjee, R. (2011). Studies on the Coordination Chemistry of Vanadium, Barium and Cobalamins [Doctoral dissertation, Kent State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=kent1300909587

    APA Style (7th edition)

  • Mukherjee, Riya. Studies on the Coordination Chemistry of Vanadium, Barium and Cobalamins. 2011. Kent State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=kent1300909587.

    MLA Style (8th edition)

  • Mukherjee, Riya. "Studies on the Coordination Chemistry of Vanadium, Barium and Cobalamins." Doctoral dissertation, Kent State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=kent1300909587

    Chicago Manual of Style (17th edition)