The paper presents a combined experimental and computational study on a mixed chelate copper(II) complex containing the bidentate ligands N,N-diethyl,N'-benzyl-1,2-diaminoethane (diamEt) and 1-phenyl-1,3-butanedione (Ph-acac). The complex [Cu(Ph-acac)(diamEt)]ClO4 was characterized by elemental analysis, IR, molar conductivity measurements and single crystal X-ray analysis. The square pyramidal geometry of the complex made it a good solvatochromic probe with the color change range from purple to green in 14 organic solvents. The observed solvatochromism was analyzed by statistical method. The obtained results revealed that the donor number (DN) parameter of the solvent plays a dominate contribution to the observed positive solvatochromism. The cationic structure of the complex was optimized by DFT methods. Infrared spectral analysis of the compound was carried out by theoretical calculation and compared with the experimental spectrum to assign the vibrational transitions. The solvatochromic behavior of the complex was also explored by TD-DFT method in different solvents. The calculated visible absorption spectra of the complex were in harmony with the experimental ones.
