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How different is pyrimidine as a core component of DNA base from its diazine isomers: A DFT study?
Author(s) -
Chatterjee Subhojyoti,
Wang Feng
Publication year - 2016
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.25229
Subject(s) - diazine , chemistry , ionization energy , pyrimidine , homo/lumo , density functional theory , crystallography , molecule , ionization , computational chemistry , stereochemistry , organic chemistry , ion
Recent photoemission spectroscopic (X‐ray photoemission spectra) study revealed less dramatic chemical changes for pyrimidine (PyM, 1, 3‐diazine) with in its ionization potential. Present systematic study using density functional theory calculations shows that PyM is indeed quite different from its diazine isomers (PyD, 1, 2‐diazine and PyA, 1, 4‐diazine). It is discovered that the most stable isomer PyM is relaxed from C 2V to C 1 point symmetry with a total electronic energy deduction of −15.86 kcal.mol −1 . Although not substantial, PyM has the smallest molecule shape (electronic spatial extent) and the largest HOMO‐LUMO energy gap of 5.65 eV; only one absorption band in the region of 200–300 nm of the UV‐Vis spectrum but three clusters of chemical shift in the carbon and hydrogen NMR spectra. The energy decomposition analyses revealed that the interaction energy (Δ E Int ) of PyM is preferred over PyA by 4.08 kcal.mol −1 and over PyD by 22.32 kcal.mol −1 , with the preferred NCN bond revealed by graph theory.