Dresden 2014 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 37: Poster Session 2
CPP 37.72: Poster
Mittwoch, 2. April 2014, 15:00–19:00, P3
Determining the stereochemistry and key excitations in the CD spectra of organic molecules by theoretical methods — •Zlatko Brkljača1, David M. Smith2,3, and Ana-Sunčana Smith1,2 — 1Institut für Theoretische Physik, Universität Erlangen–Nürnberg, Erlangen, Germany — 2Institute Ruđer Bošković, Zagreb, Croatia — 3Computer Chemie Centrum, Universität Erlangen–Nürnberg, Erlangen, Germany
Circular dichroism (CD) spectroscopy is one of the most useful methods for the determination of the absolute configuration of optically active molecules, which is one of the key aspects of molecular stereochemistry. However, since the CD spectrum very strongly depends on the molecular flexibility of the chromophores, the interpretation of the experimental data is challenging, and hence theoretical modelling is necessary to properly assign the absolute configurations. In a recent study we have shown that a combination of replica exchange molecular dynamics, clustering procedure, and TD-DFT methods can provide a general framework for the calculation of the CD spectra of flexible molecules. We find that successful modelling of CD spectra requires systematic treatment of the solvent induced polarisation. We validate our methodology by finding excellent agreement with the experimental spectra of 3 novel compounds, namely rhodomyrtals 1–3, for which we successfully determine the absolute configurations. We furthermore apply our method to flexible peptides and explore how the predominant amide and aromatic excitations shape the overall result.