NMR 1H-Shielding Constants of hydrogen-bond donor reflect manifestation of the Pauli principle.

FONSECA GUERRA, CÉLIA; M. NATALIA C. ZARYCZ

San Luis

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica; 2019

NMR spectroscopy is one of the most useful methods fordetection and characterization of hydrogen bond (H-bond) interactions inbiological systems. For H-bonds X-H⋯Y, where X and Y areO or N, it is generally believed that a decrease of 1H-shielding constants relatesto a shortening of H-bonds donor-acceptor distance. Here, we investigated computationallythe trend of 1H-shielding constants for hydrogen-bonded protons in a series ofGuanine C8-substituted GC pair model compounds as a function of the molecularstructure. Furthermore, the electron density distribution around the hydrogen atomwas analyzed with the Voronoi deformation density (VDD) method. Our findings demonstratethat 1H-shielding values of the hydrogen bond are determined by the depletionof charge around the hydrogen atom which stems from the fact that electrons obeythe Pauli exclusion principle.