Effect of non-covalent interactions on the stability and structural properties of 2,4-dioxo-4-phenylbutanoic complex:...

The 2,4-dioxo-4-phenylbutanoic acid (DPBA) is a subject of interest in pharmaceutical research, particularly in developing new drugs targeting viral and bacterial infections. Complexation with metal ions can improve the stability and solubility of organic compounds. The present study uses quantum chemical calculations to explore the structural and electronic results arising from the interaction between the metal cation (Fe²⁺) and the π-system of DPBA in different solvents. For this purpose, the analyses of atoms in molecules (AIM) and natural bond orbital (NBO) are employed to comprehend the interaction features and the charge delocalization during the process of complexation. The results demonstrate that the strongest/weakest interactions are evident when the complex is situated in non-polar/polar solvents, respectively. In addition, the investigated complex exhibits two intramolecular hydrogen bonds (IMHBs) characterized by the O-H···O motif. The results indicate that the HBs present in the complex fall within the category of weak to medium HBs. Moreover, the O-H···O HBs are influenced by cation-π interactions, which can increase/decrease their strength in polar/non-polar solvents. To enhance understanding of the interactions above, an examination is conducted on various physical properties including the energy gap, electronic chemical potential, chemical hardness, softness, and electrophilicity power.

All calculations are conducted within the density functional theory (DFT) using the ωB97XD functional and 6-311 +  + G(d,p) basis set. The computations are performed using the quantum chemistry package GAMESS, and the obtained results are visualized by employing the GaussView program.