Synthesis and characterization of novel N-functionalized macrocyclic dioxotetraamines bearing 8-hydroxyquinoline and its metal complexes: Stability in aqueous solutions

Abstract

<span style="font-size:12.0pt;font-family:" times="" new="" roman";mso-ansi-language:nl"="" lang="NL">Novel 4-(5'-8'-hydroxyquinoline)methylene-1,4,7, 10-tetraazacyclotridecane-

11,13-dione ligand (L) has been synthesized by simple method, and characterized by elemental analyses, IR and ¹H NMR. It has two chelating sites each able to react with a

transition metal ion to form complexes. At 25.0 0.1^oC, I = 0.1 mol/dm³ NaNO₃, potentiometric titrations have been performed to determine the protonation of L-5-R-1, 10-phenanthroline-Cu(II) (R = CH₃, H, Cl, NO₂) and the stability constants of Cu(II) and

Co(II). The results show that for Cu(II) and Co(II) complexes, 8- hydroxyquinoline is a stronger chelating reagent than tetraamine[13]ene macrocycles. Molecular mechanics (MM⁺) calculations have been performed to assess the stability of ternary mixed system on CO(II)- L-5-substituted-10, 10-phenanthrolineCu(II) and CU(II)-L-5-substituted-1,10-phenanthro line-Cu(II). The coordination ability for different coordination sites and for different metal ions (Co(II) and Cu(II) at the same sites have been compared. The calculated results agree with those obtained experimentally.

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