Winthrop University Zayed Almadidy PRESENTER TODAY TOPIC IS Inorganic Biochemistry WE ARE CURRENTLY...

Winthrop UniversityWinthrop University

Zayed AlmadidyZayed AlmadidyPRESENTERPRESENTER

TODAY TOPIC ISTODAY TOPIC IS

Inorganic Biochemistry

Inorganic Biochemistry

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In Vitro Generation of CuI Through Redox Chemistry

And Its Stabilization By Means of Organic Stabilizing Ligands


Small INTROBackground on the preparation of CuI

Common three oxidation states:Cu0

CuI

CuII

Cu0 is most abundant

CuI is difficult to work with under anaerobic and aerobic conditions.

Comproportionation

CuII + Cu0D2CuI

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NOT STABLE


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Instability of Cu1+Equilibrium constants and reduction potential

CuII + e- D CuI ∑o = -.521 VCu0 D CuI + e- ∑o = .153 V

Cu0 + CuII D 2CuI ∑o = -.368 V









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Gibbs Free ENERGYNernst Equation and Equilibrium Theory

Using Equilibrium Theory:There will be 832.31 times more CuII than CuIZayed AlmadidyZayed Almadidy

PRESENTERPRESENTER








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Stabilizing Cu1+Utilizing BCA, BCS and MeCN

Cu0 + CuII D 2CuI 2CuI + X D 2(CuIX2)

LeChatlier’s Principle:Reaction will favor products






Ligand BCSStructures of Organic Agents






Ligand BCAStructures of Organic Agents






Ligand MeCNStructures of Organic Agents






Goals of the PROJECTWhat is the destination of the experiment?

Understand kinetics of comproportionation reaction.

Acquire a stability constant for the CuII—Ligand complex.

To optimize the reaction.

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Experimental PROCEDURE

Used spectrophotometer

10 uL injections of X ligand

Data recorded as a function of time

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How it was accomplished

1.5 mL Buffer

1.5 mL H2O

X mL CuII

400420

440460

480500

0

0.01

0.02

0.03

0.04

0.05

0.0600000000000001

0.0700000000000001

50uM Cu(II) + 10mM BCS in pH 7.5 MOPS Buffer

0 uM 33.22 uM66.23 uM 99.01 uM131.58 uM 163.93 uM196.08 uM 228.01 uM259.74 uM 291.26 uM322.58 uM 353.69 uM384.62 uM 415.34 uM445.86 uM 476.19 uM506.33 uM 536.28 uM566.038 uM 595.61 uM625 uM 654.21 uM683.23 uM 712.08 uM740.74 uM 769.23 uM

Wavelength (nm)

Abs

orba

nce

(AU

) 483 nm

Accidental FINDING









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Data ANALYSISWhat does it mean?

CuII + X D 2CuI CuI + 2BCS D CuIBCS2

483 nm peak indicative ofCuI/BCS Complex









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Electron SOURCEWhat is the reducing agent?

1. Water2. Buffer

One of these must have been the reducing agent









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Water HYPOTHESISHow is water yielding electrons?

4 OH- D 2 H2O + O2 + 4 e- ∑o = -.401 V4(CuX2)2+ + 4e- D 4(CuX2)1+ ∑o = .64 V

4(CuX2)2+ + 4 OH- D2 H2O + O2 + 4(CuX2)1+

∑o = .239 V









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Testing HYPOTHESISAltering the pH

4(CuX2)2+ + 4 OH- D2 H2O + O2 + 4(CuX2)1+

LeChatlier’s Principle:Increased hydroxide Increased products





pH 8.3 HEPES





0 25 50 75 100 125 150 175 200 225 2500

0.05

0.1

0.15

0.2

0.25

0.3

0.35

Various BCA Concentrations in pH 8.3 HEPES Buffer

Series1

0.00 uM

166 uM

333 uM

500 uM

666 uM

833 uM

Time (Minutes)

Ab

sorb

ance

(A

U)

pH COMPARISONSBCA ConcentrationT = 239.98 Minutes

MESAt pH 6.5

HEPES At pH 7.5

HEPES At pH 8.3 ∆ = pH 8.3 – pH 7.5

0 uM -0.0003 AU -0.0029 AU -0.0002 AU 0.003 AU

166.67 uM 0.152 AU 0.1312 AU 0.0997 AU -0.032 AU

333.33 uM 0.1448 AU 0.1685 AU 0.2037 AU 0.035 AU

500 uM 0.0891 AU 0.1693 AU 0.2571 AU 0.088 AU

666.67 uM 0.0951 AU 0.1702 AU 0.2924 AU 0.122 AU

833.33 uM 0.1497 AU 0.166 AU 0.3166 AU 0.151 AU






Cu0 to Cu1+

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How it was accomplished

Cu0 wire.056 mL CuII

0.060 mL BCA0.5 mL MOPS0.439 mL H2O

Vial A

Cu0 wire0.060 mL BCA0.5 mL MOPS0.44 mL H2O

Vial B


O2 HYPOTHESISEffect of oxygen on the reaction progression

2Cu0 D2CuI + 2e-

∑o = - 0.521 V2H+ + 2e- + ½O2 D H2O

∑o = 2.421 V

2Cu0 + 2H+ + ½ O2 D 2CuI + H2O

∑o = 1.900 V





Cu0 wire1000uM BCApH 6.5 MOPS H2O

Anaerobic Conditions


Observed RESULTS

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What did we see?

Cu0 wire1000uM BCApH 6.5 MOPS H2O

Anaerobic Aerobic


Reaction KINETICSQuantifying stabilization reaction

CuII + Cu0 + MeCN D(CuIMeCN)





50 mM CuII

Cu0

Various MeCNpH 6.5 MES H2O

Anaerobic Conditions

Rate DEPENDENCE

= k[CuII]a[MeCN]b[CuI]c

[MeCN] V0

0.25 M 0.0007360.50 M 0.003430.75 M 0.00711.00 M 0.008972.00 M 0.014094.00 M 0.0254

b = 0.754227 ± 0.072543





Cu2+ DEPENDENCE

0 12 24 36 48 60-0.0499999999999998

0.0500000000000002

0.15

0.25

0.35

0.45

0.55

0.65

0.75

Absorbance @ 562 nm of Various Concentrations of Cu(II) in 1000 mM MeCN

2.5 mM12.5 mM25 mM

Time (Minutes)

Ab

sorb

an

ce (

AU

)

𝑉0= k[CuII]a[MeCN]b[CuI]c









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Future WORKWhat’s next?

Further optimize the reaction





Determine what effect the concentration of CuI has on the kinetics

The CREW Mentor:

Dr. Nicholas GrossoehmeSharon JenkinsDestinee JohnsonBecca ToorPaisley Trantham






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