title: Hydrogen bond vibrations of 2-aminopyridine.2-pyridone, a Watson-Crick analogue of adenine.uracil.
abstract: The 2-aminopyridine.2-pyridone complex (2AP.2PY) is linked by antiparallel N-H.O=C and N-H.N hydrogen bonds, providing a model for the Watson-Crick hydrogen bond configuration of the adenine-thymine and adenine-uracil nucleobase pairs. Mass-selected S(1) <--> S(0) vibronic spectra of the supersonically cooled 2AP.2PY base pair analogue were measured by laser resonant two-photon ionization and emission spectroscopies. The hydrogen bond vibrations nu(2) (buckle, out-of-plane) and the three in-plane vibrations nu(3) (opening), nu(5) (shear), and nu(6) (stretch) were observed in the S(0) and S(1) states, giving detailed information on the stretching and deformation force constants of the (amide)N-H.N(pyridine) and the (amino)N-H.O=C hydrogen bonds. Density functional calculations with the B3LYP functional and the 6-311++G(d,p) and 6-311++G(2d,2p) basis sets yield ground-state hydrogen bond frequencies in close agreement with experiment.
authors.affiliation: Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Müller
authors.forename: Francis
authors.initials: F
authors.lastname: Talbot
authors.forename: Samuel
authors.initials: S
authors.lastname: Leutwyler
mesh_terms: D000225:Adenine / Q000737:chemistry*; D000631:Aminopyridines / Q000737:chemistry*; D020029:Base Pairing; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011728:Pyridones / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014498:Uracil / Q000737:chemistry*
chemical_list: D000631:Aminopyridines; D011728:Pyridones; C034537:adenine-uracil dimers; D014498:Uracil; C017679:2-hydroxypyridine; D000225:Adenine; C032439:alpha-aminopyridine