A new mixed-chelate copper(II) complex, [Cu(L)(acac)(ClO4)]ClO4 (L = 2-[(2-diisopropylamino-ethylamino)-methyl]-pyridine), was synthesized and thoroughly characterized. X-ray diffraction confirmed its unique, distorted square pyramidal geometry. The complex exhibited solvatochromism, with its visible absorption band shifting red (bathochromic shift) in different solvents. This sensitivity to solvent polarity suggests interactions between the solvent and the weakly bound perchlorate ion. Statistical analysis (stepwise multiple linear regression) revealed the Gutmann donor number (DN) as the key factor influencing the shift. Higher DN solvents caused a larger red shift, suggesting stronger interactions. This opens potential applications for this complex as a chromogenic sensor for solvent polarity determination.
