0181596 - UFCH-W 20030023 RIV GB eng J - Journal Article
Hobza, Pavel - Špirko, Vladimír
Why is the N1-H stretch vibration frequency of guanine shifted upon dimerization to the red and the amino N-H stretch vibration frequency to the blue?
Physical Chemistry Chemical Physics. Roč. 5, č. 6 (2003), s. 1290-1294. ISSN 1463-9076. E-ISSN 1463-9084
R&D Projects: GA MŠMT LN00A032
Institutional research plan: CEZ:AV0Z4040901
Keywords : N1-H stretch vibration * guanine shifted
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 1.959, year: 2003

Three isomers of the guanine dimer (K9K9-1, K9K7-1 and K7K7-1) possessing two N-H...O=C H-bonds were investigated theoretically using the ab initio calculations at the HF/6-31G** level. Amino groups in these isomers were not directly involved in H-bonding. Besides the red shifts of the N-H stretch vibrations (supporting the H-bonded character of these contacts) an unexpected blue shifts of amino N-H stretch vibrations was found and this conclusion fully agrees with published experimental results. The blue shift of the amino group N-H stretch vibrations in all guanine dimer structures was clarified by the planarization of the guanine amino group. Absolute values of harmonic amino N-H stretch frequencies and their shifts upon planarization were verified by performing the two-dimensional anharmonic vibrational analysis. The planarization of the guanine amino group cannot be interpreted on the basis of an electrostatic model and is due to redistribution of electron density in subsystems.
Permanent Link: http://hdl.handle.net/11104/0078139