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

34
An Introduction to An Introduction to Electrochemistry in Electrochemistry in Inorganic Chemistry Inorganic Chemistry Or Or Quack…. Quack….I see a Quack…. Quack….I see a duck duck

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

Page 1: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

An Introduction to An Introduction to Electrochemistry in Inorganic Electrochemistry in Inorganic

ChemistryChemistry

OrOr

Quack…. Quack….I see a duckQuack…. Quack….I see a duck

Page 2: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 3: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 4: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 5: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 6: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

[Cu(NH3)4]2+ (aq) [Cu(NH3)2]

+ (aq) Cu

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 1 2

Oxidation Number

-G

/F =

nE

o

Cu(NH3)4]2+

[Cu(OH2)5]2+ (aq) [Cu(OH2)2]

+ (aq) Cu

Page 7: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

N

N

N

NN

N

phenanthroline 4,7-dimethylphenanthroline 2,9-dimethylphenanthroline

Now we react the Cu(II) with a series of phenanthroline-based ligands

Eo for [CuL2]2+/[CuL2]

+ (Volts)

2,9-di-Mephen 0.823 V

4,7-di-Mephen 0.256 V

phen 0.322 V

Page 8: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 9: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 10: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

N

N

N

NN

N

phenanthroline 4,7-dimethylphenanthroline 2,9-dimethylphenanthroline

Now we react the Cu(II) with a series of phenanthroline-based ligands

Eo for [CuL2]2+/[CuL2]

+ (Volts)

2,9-di-Mephen 0.823 V

4,7-di-Mephen 0.256 V

phen 0.322 V

Page 11: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 12: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Ligand’s Influence on Redox Potential

Page 13: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Influence of coordinated atoms on redox potential

Page 14: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 15: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 16: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

THERE’S THERE’S METALS METALS

IN IN THERE!!!!!!!THERE!!!!!!!

!!!!!!

Page 17: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Follows Krebs CycleResults in oxidative phosphorylation

Electron transport chain

Yes! Every Step uses a metalloenzymeYes! Every Step uses a metalloenzyme

Page 18: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Redox Potential for Electron Transport Proteins

Page 19: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Oxidized rubredoxin (1IRO) from Clostridum pasterurianum at 1.1Å

Rubredoxin (Rd)

Page 20: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

oxidized Spinach ferredoxin (1A70) from Spinacia oleracea at 1.7Å

[2Fe] Ferredoxin

Page 21: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

[4Fe] Iron Proteins

(1BLU) from Chromatim vinosum at 2.1Å (1IUA) from Thermochromatium tepidum at 0.8Å

Page 22: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 23: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1

G

o' (

kJ

mo

l-1 r

ela

tiv

e t

o O

2)

0

50

100

150

200

250

E'o

(v

olt

s)

FMN

CoQ

NADH

cyt b

cyt c1

cyt a

cyt c

O2

Page 24: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 25: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

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

Page 26: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.
Page 27: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Reduction Potential Difference Reduction Potential Difference ==EºEº

  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 ETScan be used to synthesize ATP.

Page 28: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

The reduction potential can be related to free energy change by: Gº = -nFEº

where n = # electrons transferred = 1,2,3F = 96.5 kJ/volt, called the Faraday constant

Page 29: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

********************************************************************

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 negativevoltage -- (below it in Table)**********************************************************************

Page 30: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Standard Reduction Potential

Oxidant Reductant n Eº, vNAD+ NADH 2 -0.32acetaldehyde ethanol 2 -0.20pyruvate lactate 2 -0.19oxaloacetate malate 2 -0.171/2 O2+2H+ H2O 2 +0.82

Page 31: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Redox Function

Thermodynamics = redox potential: (G = -nFE0)

• 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 Zeff - all orbital energy levels(stronger ligand donation lower Zeff 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)

Page 32: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

-- Electrons can move through a chain of donors and acceptors

-- In the electron transport chain, electrons flow down a gradient.

-- Electrons move from a carrierwith low reduction potential (high tendency to donate electrons)toward carriers with higherreduction potential (high tendencyto accept electrons).

Page 33: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

Superoxide Dismutase[CuZnSOD]

Page 34: An Introduction to Electrochemistry in Inorganic Chemistry Or Quack…. Quack….I see a duck.

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?