Study of Spectroscopic (FTIR and UV-Vis) and Theoretical Calculations on (E)-N-(4-methoxyphenyl)-1-(5-nitro-2-(piperidin-1-yl)phenyl)Methanamine

In this study, the structure of the new Schiff base (E)-N-(4-methoxyphenyl)-1-(5-nitro-2-(piperidin-1-yl)phenyl)methanimine was investigated using experimental methods such as X-ray single crystal analysis, UV-Vis, and FTIR spectroscopy. NBO analysis, the FTIR, and UV-Vis calculations were theoretically carried out with the help of B3LYP/DFT. Additionally, the optical properties were investigated through DFT calculations, and the experimental UV-Vis spectrum was related to the HOMO–LUMO transitions. Apart from this, the volecular electrostatic surface potential and determination of thermodynamic properties for the title compound were done at the same level of theoretical approach. The structural state and crystal packing of the compound were also analyzed by three-dimensional Hirshfeld surfaces, and two-dimensional fingerprint maps. It was observed that crystallization occurs in the monoclinic system with the P2₁/n space group, along with intermolecular hydrogen bonds between C6–H6⋯O1. The π⋯π interactions detected in the molecule are present only between the R₁ and R₂ rings, while the most significant contribution to crystal packing comes from H⋯H interactions. Additionally, remarkable stabilization is provided by the highest hyperconjugative interaction between the intramolecular donor LP(1)N1 and the acceptor O1–O2.