A DFT and AIM study of blue-shifting hydrogen bonds and secondary interactions in small heterocyclic complexes

in this work, a computational study of molecular properties of small heterocyclic intermolecular systems is presented. fundamentally, the b3lyp/6-31g(d,p) and b3lyp/6-311++g(d,p) theoretical methods were used to determine the optimized geometries of the c2h4o···hcf3 and c4h6o···hcf3 heterocyclic complexes and thereby evaluate the existence of blue-shifting hydrogen bonds on these systems. a contraction of the c-h bond length of the fluoroform (hcf3) was observed by analyzing the main structural parameters. consequently, results of infrared spectrum analysis showed the blue-shift in the stretch frequency accompanied by a significant decrease in absorption intensity. with the purpose of comprehending this vibrational phenomenon, hybrid functional and split valence basis sets were used and topological parameters derived from atoms-in-molecules (aim) theory were also applied. moreover, the non-linear deviation in (o···h) anti-hydrogen bonds due to the secondary interaction (ha···fj) between the fluorine (fj) of fluoroform and axial hydrogen atoms (ha) of the heterocyclic structures was verified.