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

摘要

Novel 4-(5'-8'-hydroxyquinoline)methylene-1,4,7,10-tetraaza-cyclotridecane-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 deg C,I=0.1 mol/dm~3 NaNO_3,potentiometric titrations have been performed to determine the protonation of L-5-R-l,10-phenanthroline-Cu(II)(R=CH_3,H,Cl,NO_2)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 tetra-amine[13]ene macrocycles.Molecular mechanics(MM~+)calculations have been performed to assess the stability of ternary mixed system on Co(II)-L-5-substituted-l,10-phenanthroline-Cu(II)and Cu(II)-L-5-substituted-l,10-phenanthroline-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.