Invited lecture: NMR spectroscopic paramaters of HB containing molecules and agregates of DNA base pairs

GUSTAVO A. AUCAR; FERNANDO MARTINEZ; MARCOS MONTERO; TERESITA SANTA CRUZ

Munich

Congreso; 11th Triennial Congress of the World Association of Theoretical and Computational Chemists; 2017

Comité organizador local e internacional

The nature of the hydrogen bond, HB, as such, is still unknown, though some of its most fundamental features are being precisely described. Among the spectroscopic methods available to study molecules containing HBs, the NMR could give deeper insights about the electronic origin of properties and phenomena associated with them. One can mention two phenomena: resonance assisted HBs and charge assisted Hbs.[1]During the last few years we have being studying the dependence of NMR spectroscopic parameters with the type of HB in malonaldehyde and its derivatives.[2] They could arise from both, electronic and geometric factors. In this presentation we will show how the NMR spectroscopic parameters can be incorporated as descriptors of the magnetic nature of HBs. On the other side, π-π stacking or interbase interactions were recently studied to get a deeper understanding of the stacking forces necessary to break fragments of DNA base-pairs while leaving hydrogen bonds intact, at the level of individual pairs.[3] These studies are of great interest due to its applied use.We are then interested to study the likely effects of the stacking interactions on the NMR spectroscopic parameters. One of our main interest is to describe the effect of piling up Watson-Crick base-pairs on the magnetic properties of a given pair, using two different systems: guanine-cytosine-rich sequences and adenine-thymine-rich sequences.[4] We are also interested to answer the question about whether stacking interactions may support the appearance of cooperativity effects transmitted through the fragments of DNA. In this communication we will describe the dependence of nuclear magnetic shieldings and J-couplings with cooperativity effects, in addition to that of stacking and HB in short complexes of DNA base-pairs.Acknowledgments: The argentinian research council, CONICET and the argentinian agency for science and technology, FONCYT are greatly acknowledged for financial support.[1] P. Gilli, V. Bertolasi, L. Pretto, A. Lycka and G. Gilli. J. Am. Chem. Soc. 124, 13554 (2002). [2] M. Montero, F. Martínez and G. A. Aucar, J. Phys. Chem. A. Submitted.[3] F. Kilchherr, C. Wachauf, B. Pelz, M. Rief, M. Zacharias and H. Dietz, Science 353, aaf5508 (2016).[4] F. Martínez and G. A. Aucar, Phys. Chem. Chem Phys. Submitted.