Structural, spectroscopic (FTIR, FT-Raman and UV-Vis) investigations, Fukui function analysis and thermodynamic properties of diethyl 3,3′-(ethane-1,2-diylbis(azanediyl))(2Z,2′Z)-bis(but-2-enoate)

Diethyl 3,3′-(ethane-1,2-diylbis(azanediyl))(2Z,2′Z)-bis(but‑2-enoate) (DBE) molecule is characterized by infrared, Raman and UV–visible spectroscopic techniques. The structural parameters obtained using density functional theory (DFT) with B3LYP/6-311++G(d,p) level of theory closely match the experimental data. The molecule's characteristic functional groups were identified through vibrational spectra analysis. The IR and Raman spectra vibrational peaks were assigned based on Potential Energy Distribution (PED) analysis. Excitation wavelengths, oscillator strengths and excitation energies were determined through time dependent density functional theory (TD-DFT) calculations and compared to experimental data. Nonlinear optical (NLO) properties were calculated to predict the electric dipole moment and first-order hyperpolarizability of the molecule. The significant nonlinear optical properties values indicated that these materials possess excellent nonlinear optical properties, making them suitable for applications in telecommunication and signal processing. The Mulliken atomic charge, chemical activity analysis and Fukui functions were utilized to investigate the electron-poor, rich and reactive sites in conjunction with the optimized structures using the DFT method with B3LYP function and 6-311++G(d,p) basis set. Thermodynamic investigations have shown that key molecular parameters such as entropy, heat capacity and enthalpy increase as temperature rises.