FTIR spectra of solid samples of co-crystallized adenine and uracil were measured at 10 K in the range below 1000 cm-1. New bands ascribable to the N3H (uracil) and NH2 (adenine) out of plane vibrations, which disappear upon D-exchange, were revealed in comparison with the spectra of pure polycrystalline adenine and uracil obtained in the same conditions. The observed changes relate to the same groups that establish the H-bonds in base pairs of naturally occurring nucleic acids, despite the presence of an extra proton donor NH-group in both molecules. The well-established empirical correlation between the out of plane NH vibrational frequencies and H-bond energies was successfully applied for estimation of the latter in the mixed crystal.
|Number of pages
|Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy
|Published - Nov 2005
Bibliographical noteFunding Information:
M.R. gratefully acknowledge the financial support from the Israel Ministry for Immigrant Absorption; I.R. and R.F. acknowledge the financial support from Fundação para a Ciência e a Tecnologia, Lisbon (grant FCT #SFRH/BPD/1661/2000 and research project POCTI/43366/QUI/2001).
- Adenine-uracil nucleobase pair
- H-bonding in solids
- Low temperature FTIR