determination of torsional barriers of itaconic acid and n-acetylethanolamine using chirped-pulsed...
DESCRIPTION
Be careful what you wish for! Introduction Itaconic Acid m.p. 168 °C N-Acetylethanolamine b.p. 150 °C Be careful what you wish for!TRANSCRIPT
Determination of Torsional Barriers of Itaconic Acid and N-acetylethanolamine usingChirped-pulsed FTMW Spectroscopy.
Josiah R. Bailey, Timothy J. McMahon, Ryan G. BirdUniversity of Pittsburgh Johnstown
David PrattUniversity of Vermont
Introduction
Itaconic Acidm.p. 168 °C
N-Acetylethanolamineb.p. 150 °C
Be careful what you wish for!
CP-FTMW Spectrometer
MW Synthesizer
Arbitrary Waveform Generator
Fourier Transform
Free Induction Decay
Chirped Pulse240 MHz
500 MHzDigitizer(10 Gs/s)
Itaconic Acid
• Itaconic acid (methylenesuccinic acid) is an important chemical in the immune system’s response bacteria.
• Recently, it was discovered that white blood cell macrophages release itaconic acid to disrupt the metabolism of bacteria such as salmonella and tuberculosis.1
• How this molecule is utilized by our immune system is greatly dependent on its three-dimensional structure.
1Michelucci, A.; et.al. Proc. Natl. Acad. Sci. USA. 2013, 110, 7820
Itaconic Acid Spectrum10,000 averages~240 MHz chirped pulse50°C
Itaconic Acid Conformations
Conformer 1:0 kJ/mol
Conformer 3:14.5 kJ/mol
Conformer 2:1.7 kJ/mol
m052x/6-311g(d,p)
Itaconic Anhydride
JB95 MP2/ 6-311+G(2d,p)
A (MHz) 3914.62(3) 3901.42B (MHz) 1886.05(2) 1912.60C (MHz) 1282.791(9) 1293.768
ΔI -3.089(4) -3.185
Torsional Splitting
b-typea-type
N-Acetylethanolamine (AEA)
• AEA or (2-hydroxyethyl)acetamide contains both an acetamide and an alcohol functional group
• Amides form the backbone of peptide chains• Additionally, the alcohol group allows for an
intramolecular hydrogen bond• How this molecule folds up on itself dramatically
effects the barrier of the acetamide methyl rotor
10,000 averages~240 MHz chirped pulse40°C
AEA Spectrum
Rotational Constants and BarrierXIAM MP2/6-
311+G(2d,p)A (MHz) 5114.(1) 5103.1701B (MHz) 1726.(1) 1732.8742C (MHz) 1409.4(6) 1403.0590χaa (MHz) 1.55(3)a 1.61b
χbb (MHz) 1.54(5)a 1.66b
χcc (MHz) -3.09(5)a -3.27b
V3 (cm-1) 123.(4) 160c
aFit with A-band using JB95bb3pw91/6-311+g(df,pd)cm052x/6-31+g(d,p)
Structure vs. Barrier
~420 cm-1
24 cm-1 73 cm-1
123 cm-1
Suenram, R. D., et.al.. Journal of Molecular Spectroscopy 2001, 208, 188.
Ohashi, N., et.al., , J. Journal of Molecular Spectroscopy 2004, 227, 28.
Conclusion
• Collected and fit the spectra of itaconic anhydride and n-acetylethanolamine
• Both molecules displayed unexpected torsional splitting
• Compare similar molecules to help understand these motions
Future Work
• Research ways to heat itaconic acid without reacting it
• Study other dicarboxylic acids to see how methyl and methylene groups affects structure and dynamics
• Study more anhydrides of above molecules to further investigate the cause of the torsional splitting in itaconic acid
• Investigate the dynamics and structure of other acetamide to compare with AEA
Acknowledgements
Josiah Bailey
Bird Group at UPJ
Tim McMahon
Dr. David Pratt – University of Vermont