How different is pyrimidine as a core component of DNA base from its diazine isomers: A DFT study?

摘要: Recent photoemission spectroscopic (X-ray spectra) study revealed less dramatic chemical changes for pyrimidine (PyM, 1, 3-diazine) with in its ionization potential. Present systematic using density functional theory calculations shows that PyM is indeed quite different from diazine isomers (PyD, 2-diazine and PyA, 4-diazine). It discovered the most stable isomer relaxed C2V to C1 point symmetry a total electronic energy deduction of −15.86 kcal.mol−1. Although not substantial, has smallest molecule shape (electronic spatial extent) largest HOMO-LUMO gap 5.65 eV; only one absorption band region 200–300 nm UV-Vis spectrum but three clusters shift carbon hydrogen NMR spectra. The decomposition analyses interaction (ΔEInt) preferred over PyA by 4.08 kcal.mol−1 PyD 22.32 kcal.mol−1, NCN bond graph theory.