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KMID : 1024520100190070849
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Journal of the Environmental Sciences
2010 Volume.19 No. 7 p.849 ~ p.860
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Synthesis of New Nitrogen-Oxygen(N3O2) Pentadentate Ligands and the Substituent Effect on the Stability Constants of the Heavy(2) Metal Complexes
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Kim Sun Deuk
Lee Hye-Won
Seol Jong-Min
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Abstract
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A new N3O2 pentadentate ligand, N,N’-Bis(2-hydroxybenzyl)-ethylenetriamine(H-BHET?3HCl) was synthesized. The
hydrochloric acid salts of Br-BHET?3HCl, Cl-BHET?3HCl, CH3O-BHET?3HCl and CH3-BHET?3HCl containing Br-, Cl-, H-, CH3O- and CH3- groups at the para-site of the phenol group of the H-BHEP were synthesized. The structures of the
ligands were confirmed by C. H. N. atomic analysis and 1H NMR, 13C NMR, UV-visible and mass spectra. The calculated
stepwise protonation constants(logKnH) of the synthesized N3O2 ligands showed six steps of the proton dissociation. The
orders of the overall protonation constants(logβp) of the ligands were Br-BHET < Cl-BHET < H-BHET < CH3O-BHET <
CH3-BHET. The orders agreed well with that of para Hammett substituent constants(δp). The calculated stability
constants(logKML) between the ligands and heavy metal ions (Co(Ⅱ) , Ni(Ⅱ), Cu(Ⅱ), Zn(Ⅱ), Cd(Ⅱ) and Pb(Ⅱ)) agreed
well with the order of the overall proton dissociation constants of the ligands but they showed a reverse order in para
Hammestt substituent constants(δp). The order of the stability constants between the heavy metal ions with the synthesized ligands were Co(Ⅱ) < Ni(Ⅱ) < Cu(Ⅱ) > Zn(Ⅱ) > Cd(Ⅱ) > Pb(Ⅱ).
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KEYWORD
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N3O2 Pentadentate Ligand, Dissociation constants, Stability constants, Heavy metal ions
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