SPECTROPHOTOMETRIC INVESTIGATION OF TERNARY COMPLEX FORMATION BETWEEN 1,8-DIHYDROXY-9,10-ANTHRAQUINONE AND IMIDAZOLE WITH Co²⁺, Ni²⁺, Cu²⁺ AND Zn²⁺ IN METHANOL AT 25°C

ABSTRACT

The complexation reaction between 1,8-dihydroxy-9,10-anthraquinone (DHAQ) and imidazole (Im) and Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺ are studied spectrophotometrically in methanol at 25°C. The possibility of complex formation between metal ions and ligands are illustrated by visible spectra at different M²⁺:DHAQ:Im ratios. Computer fitting of experimental spectra to purposed chemical model using SQUAD program obtains the stability constants and stoichiometries of all resulting complexes. The species ML, ML₂ type (L=DHAQ) and MB, MB₂, MB₃ and MB₄ (B=Im) are obtained in binary systems. The species types detected in ternary systems are MLB, MLB₂, ML₂B₂. The higher stability of ternary systems over binary ones are discussed according to ΔLogX values.

Keywords:

• Complexation
• Mixed ligands
• Imidazole
• Dihydroxy anthraquinones
• Spectrophotometry
• Stability constants
• Nonaqueous solutions

Acknowledgments