OICC Press International Journal of Nano Dimension 2228-5059 8 2 2024 02 28 Theoretical calculations of solvation 12-Crown-4 (12CN4) in aqueous solution and its experimental interaction with nano CuSO4 10.22034/ijnd.2017.24995 EN Laila I. Ali Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11711, Cairo, Egypt 0000-0003-1734-7441 Shimaa Abdel Halim Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11711, Cairo, Egypt. Sameh Gamal Sanad Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11711, Cairo, Egypt Journal Article 2024 02 28 Theoretical study of the electronic structure, and nonlinear optical properties (NLO) analysis of 12-crown-4were done using Density Functional Theory (DFT) evaluations at the B3LYP/6-311G (d,p) level of theory. The optimized structure is nonlinear compound as indicated from the dihedral angles were presented. The calculated EHOMO and ELUMO energies of 12-Crown-4 (12CN4) can be used to explain the charge transfer in 12-Crown-4 (12CN4) and to calculated the global properties; the chemical hardness (η), softness (S) and electronegativity (χ). The NLO parameters: static dipole moment (µ), polarizability (α), anisotropy polarizability (Δα) and first order hyperpolarizability (βtot) of the 12-Crown-4 (12CN4) have been calculated at the same level of theory.The molecular electrostatic potential (MEP) and electrostatic potential (ESP) for the title molecule were investigated and analyzed.  Also the electronic absorption spectra were measured in ethanol and water solvents and the assignment of the observed bands has been discussed by time-dependent density functional theory (TD-DFT) calculations. The correspondences between calculated and experimental transitions energies are satisfactory. From the experimental conductance measurements, the association thermodynamic parameters (KA, ∆GA, ∆HA and ∆SA) and complex formation thermodynamic parameters (Kf, ∆Gf, ∆Hf and ∆Sf) for nano-CuSO4 in presence of 12-crown-4 (12CN4) as chelating agent in 10% ethanol – water solvents at different temperatures (298.15, 303.15, 308.15 and 313.15K) were applied and calculated.