Synthesis, characterization and thermodynamic properties of metal complexes of a phenanthroline-bridging macrocyclic ligand

Abstract

A macrocyclic ligand incorporating phenanthroline has been synthesized by the reaction of 2,9-dichloromethyl-1,10-phenanthroline with dioxo[13]aneN₄(dioxo[13]aneN₄ = 1,4,7,11-tetraazacyclotridecane-8,10-dione). The stability constants of its Cu²⁺, Co²⁺, Hg²⁺ and Pd²⁺ metal complexes have been measured by potentiometric pH titration technique. It was found that a π-dp electrostatic interaction between Cu²⁺ and the phenanthroline moiety does exist in the binary systems. Stability constants of ternary systems containing Cu²⁺, ligand L(L₁) and α-amino acids (AA, L₂) in aqueous solution were also determined. Linear free energy relationships (LFER) exist in the ternary systems.

Keywords:

• Phenanthroline
• Dioxotetraamine macrocycles
• α-Amino acids
• Metal complexes
• Thermodynamics
• LFER

Acknowledgements

This project was supported by the National Science Foundation of the P.R. China (20371018) and the National Science Foundation of Tianjin (023605811).