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OK, so you’ve made the Ru complexes. Now, how are you going to determine what it does with DNA?. Will your complex bind DNA, like this?. Will the other complexes also bind DNA?. Will your complex cleave (damage) DNA?. Will the other complexes cleave DNA?.
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OK, so you’ve made the Ru complexes. Now, how are you going to determine what it does with DNA? Will your complex bind DNA, like this? Will the other complexes also bind DNA? Will your complex cleave (damage) DNA? Will the other complexes cleave DNA?
How might their different structures affect their behavior with DNA? • Electronic Spectroscopy (UV/vis) • Cyclic Voltammetry (Ered)
Electronic Spectroscopy The Ru complexes are all orange: Won’t their UV/vis spectra be the same?
Cyclic Voltammetry A Method to Measure Electrochemical Behavior and Ered • Will the complexes have different Ru redox potentials?
The Same Question will be asked of your hemes: Can changing Heme substituents vary Fe(3+/2+) reduction potentials?
+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
+current, cathodic ic Starting at a + V, Initially no current flows + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic If a reducible species is present ic will increase + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic And continue to increase + 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
+current, cathodic ic Then ic decreases until… + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic It again reaches the background current level. + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic Now the potential is reversed + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic And as V is more positive, the reduced species can be re-oxidized + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic So ia decreases to a maximum + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic Where all has been oxidized, + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic Then ia decreases, back to the background level. + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic Important features: Ec + V -V +1.0 V -1.0 V -current, anodic ia Ea
+current, cathodic ic Ec E1/2is ~ 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 A little Fe(2+) formed + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic more Fe(2+) formed + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic Largest cathodic current, Max rate of Fe(2+) formed + V -V +1.0 V -1.0 V -current, anodic ia
+current, cathodic ic 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 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 + V -V 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 + V -V +1.0 V -1.0 V Nearly all Fe(2+) has been oxized -current, anodic ia
+current, cathodic ic + V -V +1.0 V -1.0 V All back to Fe(3+). Cycle could be run again, many times. -current, anodic ia
+current, cathodic ic Important features: Ec + V -V +1.0 V -1.0 V -current, anodic ia Ea
+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:
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…
the 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…
the 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…
the 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…
the 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…
the 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…
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
One more thing: Use of internal reference, ferrocene +ic -V + V E(1/2) values of sample are reported vs. ferrocene (example….) -ia
Schedule for Thursday Nov. 1 Calculate E(1/2) for your data immediately, both vs. reference and corrected, vs. ferrocene After that: 3:30 Everyone meet in 264 to discuss results 4:15 – Attend Seminar by Dr. Nathanial Nucci
How is the range of Heme Potentials in Respiration adjusted?