Theoretical DFT(B3LYP)/6-31+G(d) study on the prediction of the preferred interaction site of 3-methyl-4-pyrimidone with different proton donors

• 作者: Guido Maes Mayaliwa Muzomwe Okuma Emile Kasende
• 来源期刊: 自然科学期刊(英文)
• 学科: 化学
• 关键词: 3-Methyl-4-pyrimidone DFT/B3LYP CALCULATION Proton-Donor CAPABILITY
• 年，卷（期）: 2012,（5）
• 页码范围: 286-297
• 页数: 12页
• 分类号: O6

摘要

Theoretical calculations were carried out using the DFT/B3LYP/6-31+G(d) methodology in an attempt to predict the preferred interaction site of a polyfunctional heterocyclic base 3-methyl-4- pyrimidone molecule with a series of proton donors of different acidic strength, i.e. water, methanol, phenol, 1-naphtol, 2,4,5 trichlorophenol, pentachlorophenol, picric acid and hydrogen chlordide. Computed H-bond interaction energies (ΔEc), internuclear and intermolecular distances r(O…H) and r(O…O), infrared frequency shifts Δv(C=O) and (Δv(OH) are proved to be reliable parameters for predicting the preferred interaction site of 3-methyl-4-pyrimidone. These computational data suggest that the O-H…O=C complex is preferred with water, methanol, phenol, 1-naphtol, 2,4,5 trichlorophenol and pentachlorophenol. However, for H-bonding with stronger acids such as picric acid or hydrochloric acid, the computational data suggest that the H-bonding occurs at the N1 ring atom of 3-methyl-4-pyrimidone. In the O-H…O=C com- plex, where the H-bond at the carbonyl O-atom can be oriented “anti” (Ha) and “syn” (Hb) with respect to the N3 atom, the same computational data suggest a higher stability of the “anti-O” compared to the “syn-O” orientation.