N N H C HC N CH HC N CH H C Fe N HC C H N CH Fe Fe N HC N C H CH N N N N N N N N O O O O O O O O Structural Characterization and Electronic Properties of a Cyclic Non-heme-iron- dinitrosyl Complex: [Fe(NO) 2 Imidazole] 4 Eric Sundberg and Lijuan Li California State University, Long Beach
Eric Sundberg and Lijuan Li California State University, Long Beach
Jan 20, 2016
Structural Characterization and Electronic Properties of a Cyclic Non-heme-iron-dinitrosyl Complex: [Fe(NO) 2 Imidazole] 4. Eric Sundberg and Lijuan Li California State University, Long Beach. Nitric Oxide Chemistry. 30 Years ago: A major contributor to smog - PowerPoint PPT Presentation
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N N
HC
HC
NCH HC N
CH
HC
Fe
N
HC
CH
N
CH
Fe
Fe
NHC
NCH
CH
N
N
NN
N
N
NN
O O
O
O
OO
O
O
Structural Characterization and Electronic Properties of a Cyclic
Non-heme-iron-dinitrosyl Complex: [Fe(NO)2Imidazole]4
Structural Characterization and Electronic Properties of a Cyclic
Non-heme-iron-dinitrosyl Complex: [Fe(NO)2Imidazole]4
Eric Sundberg and Lijuan Li
California State University, Long Beach
Eric Sundberg and Lijuan Li
California State University, Long Beach
Nitric Oxide ChemistryNitric Oxide Chemistry• 30 Years ago:
– A major contributor to smog– An ingredient in cigarette smoke and automobile exhaust – A suspected carcinogen– An ozone depleting agent– Toxic, noxious chemical
Koshland, D. E., Jr. Science 1992, 258, 1861-1902
Nitric Oxide ChemistryNitric Oxide Chemistry
• In 1992, it was named the “Molecule of the Year” by the journal Science in an article titled, “NO News is Good News”
• In 1998 three gentlemen were awarded the nobel prize in medicine and physiology for their work involving the biological aspects of nitric oxide
Nitric Oxide ChemistryNitric Oxide Chemistry
Furchgott Ignarro MuradDiscovered that nitric oxide works as a signaling
molecule in the cardiovascular systemDiscovered that nitric oxide works as a signaling
molecule in the cardiovascular system
http://www.nobel.se/medicine/laureates/1998/index.html
Nitric Oxide ChemistryNitric Oxide Chemistry
• Maintains blood Maintains blood pressure by dilating pressure by dilating blood vesselsblood vessels
• Kills foreign invadersKills foreign invaders• Involved in Involved in
neurotransmissionneurotransmission
• Maintains blood Maintains blood pressure by dilating pressure by dilating blood vesselsblood vessels
• Kills foreign invadersKills foreign invaders• Involved in Involved in
neurotransmissionneurotransmission
• Involved in learning Involved in learning and memory processesand memory processes
• Controls platelet Controls platelet aggregationaggregation
• Stimulates penile Stimulates penile erectionserections
• Involved in learning Involved in learning and memory processesand memory processes
• Controls platelet Controls platelet aggregationaggregation
• Stimulates penile Stimulates penile erectionserections
Numerous Physiological Functions
Feldman, P. L.; Griffith, O. W.; Stuehr, D. J. Chem Eng. News 1993, 71 (Dec), 26-38
Heme Versus Non-hemeHeme Versus Non-heme• Nitrosyl (NO) on a
hemoglobin molecule• Nitrosyl attached to a
non-heme molecule• Nitrosyl attached to a
non-heme molecule
Fe
N
N
N
N
CH3
CH3CH3
CH3
COOH COOH
NO
Fe
NO
Fe
NO
NO
L
L
+ NO
Muller, B.; kleschyov, A. L.; Stoclet, J. C. Br. J. Pharm. 1996, 119, 1281-1285
Density Functional Theory
Stability UV-vis
Electrochemistry
EPR and NMR
ClassificationSynthesis
OutlineOutlineNon-heme iron Dinitroyls
Characterization
FT-IR X-ray Crystallography
SynthesisSynthesis
Fe(CO)2(NO)2 + C3H4N2
C
NN
C
O
Fe
O
O O
Starting Material:Dicarbonyldinitrosyliron(0)
N
NH
Ligand: Imidazole
SynthesisSynthesis• After 2 Hours: • After 24 Hours:
N
HN
N N
O O
Fe
C
O
N N
HC
HC
NCH HC N
CH
HC
Fe
N
HC
CH
N
CH
Fe
Fe
NHC
NCH
CH
N
N
NN
N
N
NN
O O
O
O
OO
O
O
1757.5
7
1806.8
3
2031.6
9
2088.0
1Fe(CO)2(NO)2
60
80
100
%T
1686.6
3
1731.0
1
1982.5
0
Fe(CO)(NO)2(Im)
20
40
60
80
%T
1725.9
5
1796.7
8
Fe(NO)2(Im)2
10
15
20
%T
1600 1800 2000 2200 2400 2600
Wavenumbers (cm-1)
CharacterizationCharacterization
N
HN
N N
O O
Fe
C
O
C
NN
C
O
Fe
O
O O
CharacterizationCharacterization
• X-ray Crystallography shows a cyclic compound with an acetone molecule trapped inside
Materials and MethodsMaterials and Methods
• Recrystallized [Fe(NO)2Im]4
• Nuclear Magnetic Resonance– Dissolved 50mg of sample into 2 mls of deuterated
THF and transferred to a NMR tube
– AC200 Spectrometer
• Electron Paramagnetic Resonance– Dissolved 2 mg of sample into degassed 1 ml of THF
and transferred to EPR tube
– Brooker EMX Model EPR Spectrometer
Materials and MethodsMaterials and Methods• Electrochemistry
– 3 electrode system with a gold working electrode
– THF was used as the solvent– Scan Rate of 100 mV sec-1
– 10mM [Fe(NO)2(Imidazole)]4 solution and a 0.1M electrolyte solution, (tetrabutylammonium perchlorate)
– Computer Controlled Electrochemical Analyzer
Autolab Electrochemical Insturments
http://www.ecochemie.nl/
Materials and MethodsMaterials and Methods
• UV-vis Spectroscopy– Varian 300 Bio UV-vis spectrophotometer– Dilution Series in THF: 0.1-0.8 mM
Cary Uv-vis Spectrometer
www.varianinc.com
Materials and MethodsMaterials and Methods
• Stability– FT-IR spectroscopy (Nicholet 380
Spectrometer) – 0.2mM in THF at 15 and 30 minutes
• Spin Density Functional Theory– Performed using X-ray crystallographic
coordinates– Dr. Fu-Ming Tao at Cal. State Univ. Fullerton
Nuclear Magnetic ResonanceNuclear Magnetic Resonance
ppm9.0 01.02.03.04.05.06.07.08.0
1H NMR
(H1)
(H2&H3)
H2&H3
H1
Nuclear Magnetic ResonanceNuclear Magnetic Resonance
306090120150180210240
ppm
13C NMR
C2&C3
C1
C1
C2&C3
Electron Paramagnetic ResonanceElectron Paramagnetic ResonanceElectron Paramagnetic ResonanceElectron Paramagnetic Resonance
g=2.03
20G
Hyperfine Structure
ElectrochemistryElectrochemistry
UV-vis SpectroscopyUV-vis Spectroscopy
MLCT
d-d transitions
Stability under Oxygen
1725.9
5
1796.7
8
Fe(NO)2(Im)2
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
%T
ransm
ittance
1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400
Wavenumbers (cm-1)
Spin Density Functional Calculations
• Will provide wavefunction analysis of the molecule = a + b + c…– A diagram of the electron density on the
molecule
1757.5
7
1806.8
3
2031.6
9
2088.0
1Fe(CO)2(NO)2
60
80
100
%T
1686.6
3
1731.0
1
1982.5
0
Fe(CO)(NO)2(Im)
20
40
60
80
%T
1725.9
5
1796.7
8
Fe(NO)2(Im)2
10
15
20
%T
1600 1800 2000 2200 2400 2600
Wavenumbers (cm-1)
Spin Density Functional Calculations
N
HN
N N
O O
Fe
C
O
C
NN
C
O
Fe
O
O O
Spin Density Functional CalculationsSpin Density Functional Calculations
Fe ON:NNH
:
:NN
: N OFe +
Fe
Single- Substituted Product
Cyclic Product
ConclusionConclusion• [Fe(NO)2Im]4 has been characterized by
– X-ray Crystallography and FT-IR Spectroscopy– NMR and EPR techniques
• Electrochemistry showed 2 chemically reversible reductions
• UV-vis spectroscopy showed MLCT and d-d orbital transitions
ConclusionConclusion
• Low stability of compound in solution when exposed to oxygen
• Spin Density Functional Theory showed excess electronic density on the imidazole
• Potential Medicinal Applications
Future StudiesFuture Studies
• Mass spectrometry
• Elemental analysis
• NMR studies of decomposed sample
• Laser flash photolysis
AcknowledgementsAcknowledgements
• Dr. Lijuan Li
• Dr. Ximeng Wang
• The Beckman Scholars Foundation
• Howard Huges Medical Institute
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