H-bonded complexes of the 5-fluorouracil anticancer drug with various six-membered cyclic nitrosamine compounds:A quantum chemical study

We present detailed theoretical studies of the H-bonded complexes formed from interaction between 5-fluorouracil and various six-membered cyclic nitrosamine compounds. In this study, an investigation on intermolecular interactions in X-NA…5FU (X = CH2, SiH2,BH, AlH, NH, PH, O and S) complexes is carried out using density functional theory. The calculations are conducted on B3LYP/6-311++G** level of theory for optimization of geometries of complexes and monomers. Furthermore, quantum theory of ‘‘Atoms in Molecules’’ (AIM) and natural bond orbital (NBO) method are applied to analyze H-bond interactions in respective complexes. The electron density (?) and Laplacian (?2?) properties, estimated by atoms in molecules calculations, indicate that O…H bonds possess low ? and positive ?2? values that these properties are typical for closed shell interactions. In addition, the examination of H-bond in these complexes by quantum theory of NBO method supports the ab initio results. Natural population analysis data, the electron density, and Laplacian properties, as well as, the ?(C-H) and ?(N-H) frequencies of complexes, calculated at the B3LYP/6-311++G** level of theory, are used to evaluate the H-bond interactions. Several correlations between topological, geometrical and energetic parameters are also found.

کلیدواژه ها:

Interaction energy ، intermolecular hydrogen bonding ، AIM and NBO