title: Infrared depletion spectra of 2-aminopyridine2-pyridone, a Watson-Crick mimic of adenine.uracil.
abstract: The 2-aminopyridine2-pyridone (2AP2PY) dimer is linked by 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-specific infrared spectra of 2AP2PY and its seven N-H deuterated isotopomers have been measured between 2550 and 3650 cm(-1) by IR laser depletion combined with UV two-color resonant two-photon ionization. The 2PY amide N-H stretch is a very intense band spread over the range 2700-3000 cm(-1) due to large anharmonic couplings. It is shifted to lower frequency by 710 cm(-1) or approximately 20% upon H bonding to 2AP. On the 2AP moiety, the "bound" amino N-H stretch gives rise to a sharp band at 3140 cm(-1), which is downshifted by 354 cm(-1) or approximately 10% upon H bonding to 2PY. The amino group "free" N-H stretch and the H-N-H bend overtone are sharp bands at approximately 3530 cm(-1) and 3320 cm(-1). Ab initio structures and harmonic vibrations were calculated at the Hartree-Fock level and with the PW91 and B3LYP density functionals. The PW91/6-311++G(d,p) method provides excellent predictions for the frequencies and IR intensities of all the isotopomers.
authors.affiliation: Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
authors.forename: Jann A
authors.initials: JA
authors.lastname: Frey
authors.forename: Andreas
authors.initials: A
authors.lastname: Müller
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Frey
authors.forename: Samuel
authors.initials: S
authors.lastname: Leutwyler
mesh_terms: D000225:Adenine / Q000737:chemistry*; D000631:Aminopyridines / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods*; D019281:Dimerization; D006859:Hydrogen / Q000737:chemistry; D007259:Infrared Rays; D013058:Mass Spectrometry; D008956:Models, Chemical; D009584:Nitrogen / Q000737:chemistry; D016011:Normal Distribution; D009690:Nucleic Acid Conformation; D011728:Pyridones / Q000737:chemistry*; D012984:Software; D013055:Spectrophotometry, Infrared; D014466:Ultraviolet Rays; D014498:Uracil / Q000737:chemistry*
chemical_list: C515690:2-aminopyridine2-pyridone; D000631:Aminopyridines; D011728:Pyridones; D014498:Uracil; C017679:2-hydroxypyridine; D006859:Hydrogen; D000225:Adenine; D009584:Nitrogen