Hannover 2013 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 22: Biomolecules
MO 22.2: Vortrag
Donnerstag, 21. März 2013, 11:15–11:30, F 107
The Hydrogen Bonding in Vitamin C: A Puzzle Disentangled — Isabel Peña1, Adam M. Daly1, Carlos Cabezas1, Santiago Mata1, Celina Bermúdez1, Amaya Niño1, Juan C. López1, José L. Alonso1, and •Jens-Uwe Grabow2 — 1Universidad de Valladolid, Valladolid, Spain — 2Gottfried-Wilhelm-Leibniz-Universität, Hannover, Germany
Vitamin C is a gamma-lactone ring where up to eleven intramolecular hydrogen bonds are feasible, establishing three different types of hydrogen bonding. This hydrogen bonding puzzle can stabilize a myriad of low-energy conformers; high-level ab initio computations predict up to 17 conformers within 900 cm-1.
There is still no conclusive experimental information on the spatial nature of the hydrogen bonding network that governs the molecule's five degrees of conformational freedom. The only gas phase experiments of any vitamin have been limited to photoelectron spectra of vitamins A and D.
Supersonic-jet Fourier transform microwave (FTMW) spectroscopy is unrivalled in discerning amongst conformers due to the high resolution that is making it sensitive to even subtle structural changes. Here, we used a broadband FTMW instrument called IMPACT (in-phase/quadrature-phase-modulation passage-acquired-coherence technique) in combination with LASER ablation to overcome the vaporization difficulties of vitamin C - using the third harmonic (355nm) of a ps-LASER. Notably, this IMPACT-FTMW implementation offers the well-known sub-Doppler resolution of a coaxial arrangement.