+ current, cathodic ic + potential, V - potential, V - current, anodic

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+ current, cathodic ic + potential, V - potential, V - current, anodic ia

+ current, cathodic ic Reduction + potential, V - potential, V Oxidation - current, anodic ia

+ current, cathodic ic When no electroactive species is present, no current flows, no ic nor ia This is what background electrolyte should look like. + V - V +1.0 V -1.0 V - current, anodic ia

Initially no current flows + current, cathodic ic Starting at a + V, Initially no current flows + V - V +1.0 V -1.0 V - current, anodic ia

is present ic will increase + current, cathodic ic If a reducible species is present ic will increase + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

And continue to increase + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

Until all of the species is reduced. ic has reached a maximum. + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

Then ic decreases until… + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

background current level. + current, cathodic ic It again reaches the background current level. + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

Now the potential is reversed + current, cathodic ic - current, anodic ia

And as V is more positive, The reduced species can be Re-oxidixed + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

So ia decreases to a maximum + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

Where all has been oxidized, + current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

Then ia decreases, back to the background level. + current, cathodic - current, anodic ia

Important features: + current, cathodic ic +1.0 V -1.0 V Ec + V - V +1.0 V -1.0 V - current, anodic ia Ea

+ current, cathodic ic E1/2 is ~ EoRed +1.0 V -1.0 V - current, anodic Ec E1/2 is ~ EoRed E1/2 + V - V +1.0 V -1.0 V - current, anodic ia Ea

+ current, cathodic ic Using an Fe(3+) heme, Fe is electroactive, (and also the heme!) … All Fe(3+) + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia A little Fe(2+) formed + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia more Fe(2+) formed + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia Largest cathodic current, Max rate of Fe(2+) formed + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia Little Fe(3+) left; Less Fe(2+) forms; Decrease in ic + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia all Fe(2+) now + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia A little Fe(2+) is re-oxidized to Fe(3+) +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic + V - V +1.0 V -1.0 V - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia Nearly all Fe(2+) has been oxized - current, anodic ia

+ current, cathodic ic +1.0 V -1.0 V - current, anodic ia All back to Fe(3+). Cycle could be run again, many times. - current, anodic ia

Important features: + current, cathodic ic +1.0 V -1.0 V Ec + V - V +1.0 V -1.0 V - current, anodic ia Ea

E1/2 for Fe(3+/2+) reduction + current, cathodic ic Ec E1/2 for Fe(3+/2+) reduction E1/2 + V - V +1.0 V -1.0 V - current, anodic ia Ea

the black box Working Electrode: Where the redox reaction action occurs

the black box Working Electrode: Where the redox reaction action occurs Reference Electrode: Defines “0” potential for the cell. We use Ag/AgCl

the black box Working Electrode: Where the redox reaction action occurs Auxilliary Electrode: Needed to complete circuit. We use a Pt wire Reference Electrode:

At start of CV experiment… the black box Working Electrode: Where the redox reaction action occurs Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) At start of CV experiment…

Moving up the cathodic current peak… black box Working Electrode: Where the redox reaction action occurs Fe(2+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Moving up the cathodic current peak…

Still moving up the cathodic current peak… black box Working Electrode: Where the redox reaction action occurs Fe(2+) Fe(3+) Fe(3+) Fe(3+) Fe(2+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Still moving up the cathodic current peak…

After the maximum cathodic current peak… black box Working Electrode: Where the redox reaction action occurs Fe(2+) Fe(2+) Fe(3+) Fe(3+) Fe(2+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) After the maximum cathodic current peak…

Moving down the anodic current peak… black box Working Electrode: Where the redox reaction action occurs Fe(2+) Fe(3+) Fe(3+) Fe(3+) Fe(2+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Moving down the anodic current peak…

Sill moving down the anodic current peak… black box Working Electrode: Where the redox reaction action occurs Fe(2+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Sill moving down the anodic current peak…

At end of CV experiment… the black box Working Electrode: Where the redox reaction action occurs Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) Fe(3+) At end of CV experiment…

In your CV scans of Fe(porphyrin)Cl, you will see: + ic - V + V Interpretation???? - ia

How is the range of Heme Potentials in Respiration adjusted?

The Question asked: Can changing Heme substituents vary Fe(3+/2+) redcution potentials?