2. An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck

7. [Cu(NH 3 ) 4 ] 2+ (aq) [Cu(NH 3 ) 2 ] + (aq) Cu [Cu(OH 2 ) 5 ] 2+ (aq) [Cu(OH 2 ) 2 ] + (aq) Cu

8. phenanthroline 4,7-dimethylphenanthroline 2,9-dimethylphenanthroline Now we react the Cu(II) with a series of phenanthroline-based ligands E o for [CuL 2 ] 2+ /[CuL 2 ] + (Volts) 2,9-di-Mephen0.823 V 4,7-di-Mephen0.256 V phen0.322 V

11. phenanthroline 4,7-dimethylphenanthroline 2,9-dimethylphenanthroline Now we react the Cu(II) with a series of phenanthroline-based ligands E o for [CuL 2 ] 2+ /[CuL 2 ] + (Volts) 2,9-di-Mephen0.823 V 4,7-di-Mephen0.256 V phen0.322 V

13. Ligand’s Influence on Redox Potential

14. Influence of coordinated atoms on redox potential

17. THERE’S METALS IN THERE!!!!!!!!!!

18. Follows Krebs Cycle Results in oxidative phosphorylation Electron transport chainYes! Every Step uses a metalloenzyme

19. Redox Potential for Electron Transport Proteins

20. Oxidized rubredoxin ( 1IRO ) from Clostridum pasterurianum at 1.1Å Rubredoxin (Rd)

21. oxidized Spinach ferredoxin ( 1A70 ) from Spinacia oleracea at 1.7Å [2Fe] Ferredoxin

22. [4Fe] Iron Proteins ( 1BLU ) from Chromatim vinosum at 2.1Å( 1IUA ) from Thermochromatium tepidum at 0.8Å

26. So, the more negative the reduction potential is, the easier a reductant can reduce an oxidant and The more positive the reductive potential is, the easier an oxidant can oxidize a reductant The difference in reduction potential must be important

28. Reduction Potential Difference =  Eº   Eº = E°  (acceptor) - E  (donor)  measured in volts.  The more positive the reduction potential difference is, the easier the redox reaction  Work can be derived from the transfer of electrons and the ETS can be used to synthesize ATP.

29.  The reduction potential can be related to free energy change by:  Gº = -n F  Eº where n = # electrons transferred = 1,2,3 F = 96.5 kJ/volt, called the Faraday constant

30. ******************************************************************** Table of Standard Reduction Potentials --- Oxidant + e -  reductant -- e.g., M&vH, 3rd ed., p. 527 Note:  oxidants can oxidize every compound with less positive voltage -- (above it in Table)  reductants can reduce every compound with a less negative voltage -- (below it in Table) **********************************************************************

31. Standard Reduction Potential Oxidant Reductant n Eº, v NAD + NADH 2 -0.32 acetaldehyde ethanol 2 -0.20 pyruvate lactate 2 -0.19 oxaloacetate malate 2 -0.17 1/2 O 2 +2H + H 2 O 2 +0.82

32. Redox Function Thermodynamics = redox potential: (  G = -nFE 0 ) ionization energy - electronic structure a) HOMO/LUMO - redox active orbital energy (stronger metal-ligand bonding  raises the orbital energy  easier to oxidize  potential goes down) b) metal Z eff - all orbital energy levels (stronger ligand donation  lower Z eff  raised d-orbitals...) c) electron relaxation - allow for orbital reorg. after redox (creation of a hole upon oxidation  passive electrons shift  larger thermodynamic driving force  potential goes down)

33. -- Electrons can move through a chain of donors and acceptors -- In the electron transport chain, electrons flow down a gradient. -- Electrons move from a carrier with low reduction potential (high tendency to donate electrons) toward carriers with higher reduction potential (high tendency to accept electrons).

34. Superoxide Dismutase [CuZnSOD]

35. 12Influenceson Redoxpotential:1)Metalcenter2 )Electrostatic (ligand charge)3)σ/π-Donor strength of ligand (pKa)4)π-Acceptor strength of ligand5)Spin state6)Steric factors/ constraints (enthatic state)How can a protein chain generate these diverse redox potentials?