412 Poster
1
Background Hydrogenase Enzyme Mimic Synthesis The synthesis of the hydrogenase enzyme mimic was completed up to compound 4. The compound was identified by IR (1650cm -1 , 1670cm -1 ) and 1 H-NMR (δ = 6.77ppm, s). The IR spectra for all complexes made showed three carbonyl peaks that did not change at 1990cm -1 , 2040cm -1 , and 2080cm -1 . Discussion Adams, Richard D. and Shaobin Miao. "Metal Carbonyl Derivatives of Sulfur-Containing Quinones and Hydroquinones: Synthesis, Structures, and Electrochemical Properties ." Inorganic Chemistry 43.26 (2004): 8414-8426. Evans, David J. and Christopher J. Pickett. "Chemistry and the hydrogenases." Chem. Soc. Rev. 32 (2003): 268-275. Chen, Jinzhu, et al. "Synthesis of Diiron Hydrogenase Mimics Bearing Hydroquinone and Related Ligands. Electrochemical and Computational Studies of the Mechanism of Hydrogen Production and the Role of O-H 3 3 3 S Hydrogen Bonding†." Organometallics 29 (2010): 5330-5340. Abstract Reaction Scheme and Methods The 1 H-NMR spectra of compounds 3 and 4 show chemical shifts at 6.35 ppm, 5.40 ppm, and 5.01 ppm. This indicates the same compound is present in both spectra. It can be determined that the compound present is not the starting chloroquinone by comparing both spectra against the chloroquinone 1 H-NMR spectrum. The chloroquinone chemical shifts are further downfield indicating the protons on the chloroquinone are more deshielded than when complexed with compound 2. The shift for the single proton on compound 4 is present at 6.77ppm. The integration of compound 3’s protons was done first to show that 3 was present. The integrations was done on H A to give a value of 2.08 which indicates a ratio of 1:2 for compounds 3 and 4. For further verification, the IR of compound 4 shows carbonyl stretching peaks at 1650cm -1 and 1670cm -1 that are not present in the IR spectra of compounds 2 and 3. Sean Trumper The reactions performed gave very low yields of product. The percent yield of compounds 2, 3, and 4 were 24.58%, 22.45%, and 15.12% respectively. A possible reason for the low percent yields is the ability of the compounds to decompose while being purified on a column. Dr. Richard S. Glass, Dept. Of Chemistry, University of Arizona Matthew Swenson, Dept. Of Chemistry, University of Arizona Fe Fe S S X NC OC H 2 O CO CN S H Cys [4Fe4S] C O The Hydrogenase enzyme is a protein used by the human body to catalyze the oxidation and reduction of molecular hydrogen. This reversible redox reaction plays an important role in glycolysis. The enzyme produces H 2 from 2H + . The enzyme catalyzes this reaction with remarkable efficiency, and therefore is being investigated to determine the possible commercial production of H 2 as an alternative fuel. The goal of this project was to synthesize hydrogenzase mimics containing redox active quinone ligands to mimic the electron transport chain of the active site. The structure of the mimic is shown on the left with a chlorine for the R group. Results The mimic that was to be synthesized would have given an EPR spectrum with a G value differing from the previously made mimics shown above. As seen above the addition of the [2Fe2S] cluster shifts the G value to the left indicating the electron is more delocalized around the [2Fe2S] cluster rather than the quinone. References Acknowledgements Synthesis of Compound 2 First 20 mL of 1 was added to a round bottom flask containing 100 mL MeOH, 60 mL KOH. Next, 26.13 g of S 8 was added, followed by the addition 1 mole of HCl in 150 mL H 2 O over three hours via liquid addition funnel. The reaction was let sit for another 4 hours and was purified by column chromatography. Synthesis of Compound 3 To a quartz tube, 10 mL of DCM, 300 mg of 2, and 100 mg of the chloroquinone were added. The tube was let to react for 3 hours while under intense UV radiation. The product was purified via column chromatography. IR Spectra for Compounds 2, 3, and 4. Three carbonyl peaks are seen, 1990cm -1 , 2040cm -1 , and 2080cm -1 , representing the three different C=O ligands attached to iron. Two peaks 1650cm -1 and 1670cm -1 in the spectrum for compound 4 represent the carbonyls now present on the ring. The next steps in the research are to synthesize compound 5 and run the two different derivatives on EPR. The EPR spectra will show the effect of the two different R groups (Cl, OMe) on the placement within the complex of a radical electron. The different spectra will serve as a guideline for other electron donating and electron withdrawing groups. The difference in electron character has a large impact on the efficiency of the hydrogenase enzyme mimics. Synthesis of Compound 4 To a round bottom flask, 20 mL of DCM, 100mg of 3, and 60 mg of DDQ were added. The reaction was stirred for 2 hours. After 2 hours the solution was concentrated and purified by column chromatography. Synthesis of Compound 5 To a round bottom flask, add 20 mL THF, 20 mg of compound 4, and 2.0 mL of ONMe 3 is added dropwise over 5 minutes. The reaction is let sit for 3 hours then filtered and washed with cold methanol. The compound is then purified by column chromatography. 80 82 84 86 88 90 92 94 96 98 100 1500 1600 1700 1800 1900 2000 2100 2200 % Transmi*ance Wavenumber cm 1 Compound 2 83 85 87 89 91 93 95 97 99 101 1500 1600 1700 1800 1900 2000 2100 2200 % Transmi*ance Wavenumber cm 1 Compound 3 40 45 50 55 60 65 70 75 80 85 90 1500 1600 1700 1800 1900 2000 2100 2200 % Transmi*ance Wavenumber cm1 Compound 4 The enzyme is a large protein with an active site containing an [2Fe2S] cluster. The enzyme uses the [4Fe4S] cluster as an electron transport chain to shovel electrons to the [2Fe2S] active Fe Fe S S PPh3 OC CO CO OC PPh3 O O R Hydrogenase Enzyme Active Site EPR of the Naphthaquinone Series 3444 3449 3454 3459 3464 3469 3474 3479 Magnetic Field (G) Sample Spectra provided by Matthew Swenson Department of Chemistry Reaction Scheme OC Fe CO CO CO CO MeOH/KOH (RT) S 8 (excess) 0 o C HCl 0 o C Fe Fe S S CO OC CO CO OC OC O O R hv Fe Fe S S CO OC CO CO OC OC OH HO R 1 2 3 O O Cl Cl NC NC Fe Fe S S CO OC CO CO OC OC O O R THF, -78 o C 4 ONMe 3 , PPh 3 THF Fe Fe S S PPh 3 OC CO CO OC Ph 3 P O O R 5 R = Cl, OMe Fe Fe S S CO OC CO CO OC OC O O Cl H B H C H D H B H D H C 1 H-NMR Compound 3 Fe Fe S S CO OC CO CO OC OC O O Cl H A H A H B H D H C 1 H-NMR Compound 4 Future Research 1 H-NMR ChloroQuinone O O Cl H A H B H C H B H A H C Fe Fe S S CO OC CO CO OC OC O O Cl H B H C H D site. The compound synthesized is a mimic of this active site with a quinone acting as the ETC. The compound synthesized was to be analyzed by electron paramagnetic resonance (EPR). This analysis would show where a free radical electron would be delocalized to, either delocalized to the [2Fe2S] complex or to the quinone. The spectrum would then be compared to other iron quinone complexes. A sample EPR spectra is show below.
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Transcript of 412 Poster
Background
Hydrogenase Enzyme Mimic Synthesis q The synthesis of the hydrogenase enzyme mimic was completed up to compound 4. The compound was identified by IR (1650cm-1, 1670cm-1) and 1H-NMR (δ = 6.77ppm, s). The IR spectra for all complexes made showed three carbonyl peaks that did not change at 1990cm-1, 2040cm-1, and 2080cm-1.
Discussion
q Adams, Richard D. and Shaobin Miao. "Metal Carbonyl Der ivat ives of Sul fur-Contain ing Quinones and Hydroquinones: Synthesis, Structures, and Electrochemical Properties ." Inorganic Chemistry 43.26 (2004): 8414-8426. q Evans, David J. and Christopher J. Pickett. "Chemistry and the hydrogenases." Chem. Soc. Rev. 32 (2003): 268-275. q Chen, Jinzhu, et al. "Synthesis of Diiron Hydrogenase Mimics Bearing Hydroquinone and Related Ligands. Electrochemical and Computational Studies of the Mechanism of Hydrogen Production and the Role of O-H 3 3 3 S Hydrogen Bonding†." Organometallics 29 (2010): 5330-5340.
Abstract Reaction Scheme and Methods q The 1H-NMR spectra of compounds 3 and 4 show chemical shifts at 6.35 ppm, 5.40 ppm, and 5.01 ppm. This indicates the same compound is present in both spectra. It can be determined that the compound present is not the starting chloroquinone by comparing both spectra against the chloroquinone 1H-NMR spectrum. The chloroquinone chemical shifts are further downfield indicating the protons on the chloroquinone are more deshielded than when complexed with compound 2. The shift for the single proton on compound 4 is present at 6.77ppm. The integration of compound 3’s protons was done first to show that 3 was present. The integrations was done on HA to give a value of 2.08 which indicates a ratio of 1:2 for compounds 3 and 4. For further verification, the IR of compound 4 shows carbonyl stretching peaks at 1650cm-1 and 1670cm-1 that are not present in the IR spectra of compounds 2 and 3.
Sean Trumper
q The reactions performed gave very low yields of product. The percent yield of compounds 2, 3, and 4 were 24.58%, 22.45%, and 15.12% respectively. A possible reason for the low percent yields is the ability of the compounds to decompose while being purified on a column.
q Dr. Richard S. Glass, Dept. Of Chemistry, University of Arizona q Matthew Swenson, Dept. Of Chemistry, University of Arizona
Fe Fe
S S
X
NCOC
H2O
COCN
SH
Cys
[4Fe4S]
CO
q The Hydrogenase enzyme is a protein used by the human body to catalyze the oxidation and reduction of molecular hydrogen. This reversible redox reaction plays an important role in glycolysis. The enzyme produces H2 from 2H+. The enzyme catalyzes this reaction with remarkable efficiency, and therefore is being investigated to determine the possible commercial production of H2 as an alternative fuel.
q The goal of this project was to synthesize hydrogenzase mimics containing redox active quinone ligands to mimic the electron transport chain of the active site. The structure of the mimic is shown on the left with a chlorine for the R group.
Results
q The mimic that was to be synthesized would have given an EPR spectrum with a G value differing from the previously made mimics shown above. As seen above the addition of the [2Fe2S] cluster shifts the G value to the left indicating the electron is more delocalized around the [2Fe2S] cluster rather than the quinone.
References
Acknowledgements
Synthesis of Compound 2 q First 20 mL of 1 was added to a round bottom flask containing 100 mL MeOH, 60 mL KOH. Next, 26.13 g of S8 was added, followed by the addition 1 mole of HCl in 150 mL H2O over three hours via liquid addition funnel. The reaction was let sit for another 4 hours and was purified by column chromatography.
Synthesis of Compound 3 q To a quartz tube, 10 mL of DCM, 300 mg of 2, and 100 mg of the chloroquinone were added. The tube was let to react for 3 hours while under intense UV radiation. The product was purified via column chromatography.
q IR Spectra for Compounds 2, 3, and 4. Three carbonyl peaks are seen, 1990cm-1, 2040cm-1, and 2080cm-1, representing the three different C=O ligands attached to iron. Two peaks 1650cm-1 and 1670cm-1 in the spectrum for compound 4 represent the carbonyls now present on the ring.
q The next steps in the research are to synthesize compound 5 and run the two different derivatives on EPR. The EPR spectra will show the effect of the two different R groups (Cl, OMe) on the placement within the complex of a radical electron. The different spectra will serve as a guideline for other electron donating and electron withdrawing groups. The difference in electron character has a large impact on the efficiency of the hydrogenase enzyme mimics.
Synthesis of Compound 4 q To a round bottom flask, 20 mL of DCM, 100mg of 3, and 60 mg of DDQ were added. The reaction was stirred for 2 hours. After 2 hours the solution was c o n c e n t r a t e d a n d p u r i f i e d b y c o l u m n chromatography.
Synthesis of Compound 5 q To a round bottom flask, add 20 mL THF, 20 mg of compound 4, and 2.0 mL of ONMe3 is added dropwise over 5 minutes. The reaction is let sit for 3 hours then filtered and washed with cold methanol. The c o m p o u n d i s t h e n p u r i f i e d b y c o l u m n chromatography.
80
82
84
86
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90
92
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96
98
100
1500 1600 1700 1800 1900 2000 2100 2200
% Transmi*an
ce
Wavenumber cm-‐1
Compound 2
83
85
87
89
91
93
95
97
99
101
1500 1600 1700 1800 1900 2000 2100 2200
% Transmi*an
ce
Wavenumber cm-‐1
Compound 3
40
45
50
55
60
65
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75
80
85
90
1500 1600 1700 1800 1900 2000 2100 2200
% Transmi*an
ce
Wavenumber cm-‐1
Compound 4
q The enzyme is a large protein with an active site containing an [2Fe2S] cluster. The enzyme uses the [4Fe4S] c l u s t e r a s a n e l e c t r o n transport chain to shovel electrons to the [2Fe2S] active
Fe Fe
SSPPh3
OC COCOOC
PPh3
OO
R
Hydrogenase Enzyme Active Site
EPR of the Naphthaquinone Series
3444 3449 3454 3459 3464 3469 3474 3479
Magnetic Field (G)Sample Spectra provided by Matthew Swenson Department of Chemistry
Reaction Scheme
OC FeCO
CO
CO
CO
MeOH/KOH (RT)S8 (excess) 0oC
HCl 0oC
Fe Fe
SSCO
OC COCOOC
OCO O
R
hv
Fe Fe
SSCO
OC COCOOC
OC
OHHO
R
1 2 3
O
O
Cl
ClNC
NC
Fe Fe
SSCO
OC COCOOC
OC
OO
R
THF, -78oC
4
ONMe3, PPh3
THF
Fe Fe
SSPPh3
OC COCOOC
Ph3P
OO
R
5
R = Cl, OMe
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site. The compound synthesized is a mimic of this active site with a quinone acting as the ETC. q The compound synthesized was to be analyzed by electron paramagnetic resonance (EPR). This analysis would show where a free radical electron would be delocalized to, either delocalized to the [2Fe2S] complex or to the quinone. The spectrum would then be compared to other iron quinone complexes. A sample EPR spectra is show below.
