Author(s)

Mayaliwa Muzomwe, Guido Maes, Okuma Emile Kasende

Department of Chemistry, University of Leuven, Leuven, Belgium.
Faculty of Sciences, University of Kinshasa, Kinshasa, Democratic Republic of Congo;.

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 (ΔE_c), 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” (H_a) and “syn” (H_b) with respect to the N3 atom, the same computational data suggest a higher stability of the “anti-O” compared to the “syn-O” orientation.

3-Methyl-4-pyrimidone; DFT/B3LYP Calculation; Proton-Donor Capability

Muzomwe, M. , Maes, G. and Kasende, O. (2012) 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. Natural Science, 4, 286-297. doi: 10.4236/ns.2012.45041.