Heidelberg 2015 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 11: Posters 2: Novelties in Molecular Physics

MO 11.11: Poster

Dienstag, 24. März 2015, 17:00–19:00, C/Foyer

Structural investigations on an isolated depsipeptide by combined IR/UV laser spectroscopy in a molecular beam — •Dominic Bernhard, Anke Stamm, and Markus Gerhards — Physikalische Chemie, TU Kaiserslautern, Erwin-Schrödinger-Straße 52, 67663 Kaiserslautern

Depsipeptides are often found to be natural antibiotics, such as the cyclic depsipeptides beauvericin and valinomycin. For a better understanding of their antibiotic effect on a molecular level, knowledge on the structure of the isolated molecules is of importance. As a first model system we chose the linear depsipeptide cyclohexylcarbonyl-glycine-lactate-2-anisidine (CyCO-Gly-Lac-NH-PhOMe) whose structural investigation should give basic insights into conformational preferences of isolated depsipeptides. For that reason combined double and triple resonance IR/UV laser spectroscopic methods were applied in a molecular beam experiment. In combination with DFT calculations the mass- and isomerselective experimental methods are suitable tools to get information on conformational preferences of the isolated depsipeptides in the electronic ground state (S₀). The recorded spectra revealed the existence of more than one isomer in the molecular beam. A comparison of the IR spectra with DFT calculations allowed structural assignments; the influence of dispersion interactions was taken into account. The most stable structure was found to be a strongly folded one involving C-H π interactions.