theoretical investigation of interaction between 5-fluorouracil anticancer drug with various nitrosamine compounds

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-nu (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 the h-bond interactions in respective complexes. the electron density (ρ) and laplacian (s2ρ) properties, estimated by aim calculations, indicate that o…h bonds possess low ρ and positive s2ρ values which are in agreement with electrostatic character of the h-bonds. in addition, the examination of the h-bond in these complexes by quantum theory of nbo method supports the obtained results. natural population analysis data, electron density, and laplacian properties, as well as, the ʋ(c-h) and ʋ(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.