STUDIES ON THE COORDINATION CHEMISTRY OF VANADIUM, BARIUM AND COBALAMINS A dissertation submitted to Kent State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy by Riya Mukherjee May, 2011 i Dissertation written by Riya Mukherjee B.Sc., University of Calcutta, Calcutta, India, 2000 M.Sc., University of Calcutta, Calcutta, India, 2002 Ph.D., Kent State University, 2011 Approved by ___________________________________ , Chair, Doctoral Dissertation Committee Nicola E. Brasch, Ph.D. ___________________________________ , Advisor, Doctoral Dissertation Committee Nicola E. Brasch, Ph.D. ___________________________________, Member, Doctoral Dissertation Committee Scott D. Bunge, Ph.D. ___________________________________, Member, Doctoral Dissertation Committee Derek S. Damron, Ph.D. ___________________________________, Member, Doctoral Dissertation Committee Soumitra Basu, Ph.D. ___________________________________, Graduate Faculty Representative John R. D. Stalvey, Ph.D. Accepted by _______________________________, Chair, Department of Chemistry & Biochemistry Michael J. Tubergen, Ph.D. ___________________________________ , Dean, College of Arts and Sciences John R. D. Stalvey, Ph.D. ii TABLE OF CONTENTS LIST OF FIGURES……………………………………………………………………..X LIST OF TABLES…………………………………………………………………..XVII LIST OF SCHEMES……………………………………………………………….....XX DEDICATION…………………………………………………………………...…..XXII ACKNOWLEDGEMENTS………………………………………………………..XXIII ABSTRACT……………………………………………………………………….....XXV LIST OF PUBLICATIONS…………………………………………………..……..XXX CHAPTER 1: INTRODUCTION AND BACKGROUND….………………………..1 1.1.Vitamin B12 (cobalamin)……………………………………………………………....1 1.1.1. B12−dependent enzyme reactions……………………………………………....1 1.1.2. Absorption, transport, cellular uptake and intracellular processing of cobalamins……………………………………………………….......................4 1.1.3. Structure………………………………………………………………………..5 1.1.4. Oxidation states of the cobalt atom in cobalamins……………………………..7 1.1.5. Abiological syntheses of cobalamins…………………………………………...8 1.1.6. Characterization of cobalamins…………………………………………………9 1.1.6.1. X−ray crystallography……………………………………………………...9 1.1.6.2. Spectroscopic techniques………………………………………………….10 1.1.7. Non−enzymatic roles of cobalamins in alleviating chronic inflammation……13 iii 1.2. Vitamin B12−bioconjugates in targeted drug delivery………………………………14 1.3. Coordination chemistry of vanadium……………………………………………….16 1.3.1. Vanadium complexes formed in aqueous solution……………………………18 1.3.2. Vanadium in biology and medicine…………………………………………...20 CHAPTER 2: STRUCTURAL AND SPECTROSCOPIC EVIDENCE FOR THE FORMATION OF POLYNUCLEAR V(III)/CARBOXYLATO COMPLEXES IN AQUEOUS SOLUTION….………………………….22 2.1. Introduction…………………………………………………………………………22 2.2. Experimental………………………………………………………………………...24 2.2.1. Materials……………………………………………………………………….24 2.2.2. Instrumentation and Procedures…………………………………...…………..25 2.2.3. Preparation of V(III)/carboxylato solutions for NMR and UV−visible spectrosopic measurements………………………………………26 2.2.4. PFG−NMR diffusion coefficient measurements……………………………...27 3+ 2.2.5. Syntheses of complexes [V3(3−O)(−OOCCH2Br)6(OH2)3] (1) 3+ and [V3(3−O)(−OOCCH2CH3)6(OH2)3] (2) in aqueous solution………...27 2.2.6. X−ray crystallography experiment…………………………………………….28 2.3. Results and discussion……………………………………………………...………30 2.3.1. Syntheses and characterization of complexes 1 and 2 by X-ray crystallography………………………………………………………….30 2.3.2. NMR spectroscopic studies on the formation of V(III)/carboxylato complexes in aqueous solution………………………………………………………….....34 2.3.3. UV-visible spectroscopic studies on the formation of V(III)/carboxylato complexes in aqueous solution……………………………44 iv 2.4. Summary…………………………………………………………………………....48 CHAPTER 3: SELF−ASSEMBLY OF A NOVEL TWO−DIMENSIONAL BARIUM/THIODIACETATE COORDINATION POLYMER IN AQUEOUS SOLUTION……………………………………………....51 3.1 Introduction…………………………………………………………………………..51 3.2. Experimental………………………………………………………………………...52 3.2.1. Materials………………………………………………………………………..52 3.2.2. Instrumentation………………………………………………………………....53 3.2.3. Synthesis of {Ba[S(CH2COO)2(H2O)3]•2H2O}(1)………………………….....54 3.2.4. X−ray crystallography………………………………………………………….54 3.3. Results and discussion………………………………………………………………57 3.3.1. Synthesis and characterization of 1…………………………………………….57 3.3.2. Structural characterization of 1 by X−ray diffraction…………………………..61 3.4. Summary…………………………………………………………………………….66 CHAPTER 4: STUDIES ON VANADIUM−VITAMIN B12 BIOCONJUGATES INCORPORATING A HYDROXYPYRIDINONE LINKER AS POTENTIAL THERAPEUTICS FOR TREATING DIABETES…………………………………………………………….68 4.1. Introduction………………………………………………………………………....68 4.2. Experimental………………………………………………………………………..71 4.2.1. Materials………………………………………………………………………71 4.2.2. Instrumentation………………………………………………………………..71 4.2.3. PFG−NMR diffusion coefficient measurement………………………………73 v 4.2.4. Attempted separation of complexes 2 (VO2(OH/H)2L) and 3 (VO2L2) by chromatography…………………………………………………………………73 4.2.5. In−vivo blood glucose lowering properties in the STZ−rat model for Type 1 diabetes…………………………………………………………………………..74 4.3. Results and discussion………………………………………………………………75 4.3.1. Characterization of complex 1 (3−(3−hydroxy−2−methyl−1H−pyridin−4−one) 1 propylcobalamin) by H NMR and UV-visible spectroscopy……………….....75 4.3.2 Systematic study of the binding of NaVO3 to 1 by NMR, UV-vis and FTIR spectroscopy…………………………………………………………………….78 4.3.3. Measurements of the diffusion coefficients of complexes 2 and 3 by PFG NMR experiments……………………………………………………………………..86 4.3.4 In vivo blood glucose−lowering properties complex 2 in the STZ−rat model for Type 1 diabetes………………………………………………………………….88 4.4. Summary…………………………………………………………………….............90 CHAPTER 5: SYNTHESIS, SYNCHROTRON X−RAY DIFFRACTION AND KINETIC STUDIES ON THE FORMATION AND DECOMPOSITION OF A NOVEL THIOLATOCOBALAMIN OF CAPTOPRIL…………………………………………………………..92 5.1. Introduction…………………………………………………………………………92 5.2. Experimental………………………………………………………………………...94 5.2.1. Materials………………………………………………………………………..94 5.2.2. Instrumentation………………………………………………………………...95 5.2.3. Synthesis of CapSCbl………………………..………………………………...96 5.2.4. Crystallization of CapSCbl…………………………………………………….97 5.2.5. X−ray diffraction studies on CapSCbl………………………………………....97 vi 5.2.6. Kinetic measurements on the formation of CapSCbl from aquacobalamin/ hydroxycobalamin and captopril……………………………………………....101 5.2.7. Kinetic measurements on the acid−catalyzed decomposition of CapSCbl…...102 5.3. Results and discussion……………………………………………………………..103 5.3.1. Synthesis and characterization of CapSCbl…………………………………...103 5.3.2. Evidence of cis−trans isomerization of the captopril ligand in CapSCbl by 1H NMR spectroscopy………………………………………………………...106 5.3.3. Further characterization of CapSCbl by X−ray crystallography……...……....111 5.3.3.1. Evidence for the cis−trans isomerization of the captopril ligand in CapSCbl in the solid state…………………………………………….....114 5.3.3.2. Crystal packing in CapSCbl……………………………………………..115 5.3.4. Kinetic studies on the formation of CapSCbl…………………………………118 5.3.5. Kinetic studies on the acid−catalyzed decomposition of CapSCbl in aqueous solution………………………………………………………………………...126 5.4. Summary…………………………………………………………………………...131 CHAPTER 6: KINETIC STUDIES ON THE REACTION OF COB(II)ALAMIN WITH PEROXYNITRITE………………………………………….133 6.1. Introduction………………………………………………………………………...133 6.2. Experimental……………………………………………………………………….136 6.2.1. Materials………………………………………………………………………136 6.2.2. Instrumentation………………………………………………………………..136 6.2.3. Synthesis of Na+ONOO−……………………………………………………...138 6.2.4. Synthesis of cob(II)alamin (Cbl(II))…………………………………………..139 vii 6.2.5. Solution preparation…………………………………………………………...139 6.2.6. Determination of the stoichiometry of the reaction between Cbl(II) and ONOO(H)……………………………………………………………………..140 6.2.7. Kinetic measurements on the reaction of Cbl(II) with ONOO(H)……………140 6.2.8. Generation of the calibration curves for 3−nitrotyrosine and 3−hydroxytyrosine ................................................................................................................................141 • 6.2.9. Reaction of Cbl(II) with NO2 ………………………………………………...141 6.3. Results and discussion……………………………………………………………..142 6.3.1. Determination of the acid dissociation constant and the rate constant for spontaneous decomposition of ONOOH…………………………………….142 6.3.2. Determination of the molar extinction coefficients of Cbl(II)……………….144 6.3.3. Determination of the reaction stoichiometry………………………………...144 6.3.4. Kinetic studies on the reaction between Cbl(II) and ONOO(H)…………….149 6.3.5. Studies on the reaction between Cbl(II) and peroxynitrite in the presence of tyrosine……………………………………………………………………….157 6.3.6. Attempt to determine the rate constant of the reaction between Cbl(II) and • NO2 (g)……………………………………………………………………....164 6.4. Summary………………………………………………………………………….167 CHAPTER 7: KINETIC AND MECHANISTIC STUDIES ON THE REACTION BETWEEN COB(I)ALAMIN AND PEROXYNITRITE………...169 7.1. Introduction………………………………………………………………………..169 7.2. Experimental……………………………………………………………………….170 7.2.1. Materials………………………………………………………………………170 7.2.2. Instrumentation………………………………………………………………..170 viii 7.2.3. Synthesis of cob(I)alamin (Cbl(I))…………………………………………….170 7.2.4. Preparation of solutions……………………………………………………….171 7.2.5. Determination of the stoichiometry of the reaction between Cbl(I) and ONOO(H)……………………………………………………………………..172 7.2.6. Cbl(I) does not react with fully decomposed ONOO(H)……………………...172 − 7.2.7. Determining the amount