Hannover 2010 – scientific programme
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MO: Fachverband Molekülphysik
MO 17: Biomolecules
MO 17.5: Talk
Wednesday, March 10, 2010, 17:30–17:45, F 142
Aggregation of nucleosides in CDCl3 studied by FTIR spectroscopy: From self-aggregation towards the Watson-Crick base pair — •Lars Biemann1, Thomas Häber1, Klaus Schaper2, and Karl Kleinermanns1 — 1Institut für Physikalische Chemie, Heinrich-Heine Universität, 40225 Düsseldorf — 2Institut für Organische Chemie, Heinrich-Heine Universität, 40225 Düsseldorf
We reinvestigated the self-association of the nucleobase 1-cyclohexyluracil and of the nucleosides guanosine and cytidine in CDCl3 solution and present the infrared spectra of their aggregates in the spectral regions between 1500 and 1800 cm−1 and between 2700 and 3600 cm−1. Applying a simple deconvolution procedure to a series of infrared spectra measured at different concentrations allows for a separation of the contributions of monomers and clusters. This method has successfully been applied to adenine and does not require a restriction of the size of the aggregates. On this basis, wavelength dependent absolute extinction coefficients of the uracil monomer and dimers could be extracted. Comparison of the deconvoluted dimer spectra with quantum chemical calculations allows for a structural assignment of the dimer structures that coexist in solution. Extending this analysis to the guanosine-cytidine system allows for the examination of the formation of larger aggregates beyond the dimer and elucidates the question wether the Watson-Crick GC base pair is predominant in CDCl3 solution.