Mueller, Andreas published the artcileProbing the Watson-Crick, Wobble, and Sugar-Edge Hydrogen Bond Sites of Uracil and Thymine, Computed Properties of 608-34-4, the publication is Journal of Physical Chemistry A (2005), 109(23), 5055-5063, database is CAplus and MEDLINE.
The nucleobases uracil (U) and thymine (T) offer three hydrogen-bonding sites for double H-bond formation via neighboring N-H and C:O groups, giving rise to the Watson-Crick, wobble and sugar-edge hydrogen bond isomers. The hydrogen bond properties of all three sites by forming hydrogen bonded dimers of U, 1-methyluracil (1MU), 3-methyluracil (3MU), and T with 2-pyridone (2PY) are probed. The mass- and isomer-specific S1 ← S0 vibronic spectra of 2PY·U, 2PY·3MU, 2PY·1MU, and 2PY·T were measured using UV laser resonant two-photon ionization (R2PI). The spectra of the Watson-Crick and wobble isomers of 2PY·1MU were separated using UV-UV spectral hole-burning. The different isomers are identified by combining three different diagnostic tools: (1) Selective methylation of the uracil N3-H group, which allows formation of the sugar-edge isomer only, and methylation of the N1-H group, which leads to formation of the Watson-Crick and wobble isomers. (2) The exptl. S1 ← S0 origins exhibit large spectral blue shifts relative to the 2PY monomer. Ab initio CIS calculations of the spectral shifts of the different hydrogen-bonded dimers show a linear correlation with experiment This correlation allows the identification of the R2PI spectra of the weakly populated Watson-Crick and wobble isomers of both 2PY·U and 2PY·T. (3) PW91 d. functional calculation of the ground-state binding and dissociation energies De and D0 are in agreement with the assignment of the dominant hydrogen bond isomers of 2PY·U, 2PY·3MU and 2PY·T as the sugar-edge form. For 2PY·U, 2PY·T and 2PY·1MU the measured wobble:Watson-Crick:sugar-edge isomer ratios are in good agreement with the calculated ratios, based on the ab initio dissociation energies and gas-phase statistical mechanics. The Watson-Crick and wobble isomers are thereby determined to be several kcal/mol less strongly bound than the sugar-edge isomers. The 36 observed intermol. frequencies of the nine different H-bonded isomers give detailed insight into the intermol. force field.
Journal of Physical Chemistry A published new progress about 608-34-4. 608-34-4 belongs to pyrimidines, auxiliary class Pyrimidine,Amide, name is 3-Methylpyrimidine-2,4(1H,3H)-dione, and the molecular formula is C5H6N2O2, Computed Properties of 608-34-4.
Referemce:
https://pubchem.ncbi.nlm.nih.gov/compound/Pyrimidine,
Pyrimidine – Wikipedia