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KMID : 1024520110200060687
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Journal of the Environmental Sciences
2011 Volume.20 No. 6 p.687 ~ p.700
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Synthesis of Pentadentate Nitrogen-Oxygen(N3-O2) Ligands with Substituents and the Determination of Stability Constants of Their Heavy(II) Metal Complexes
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Kim Sun Deuk
Seol Jong-Min
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Abstract
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A new pentadentate ligand, H-BHPT, was synthesized. Hydrochloric acid salts of Br-BHPT, Cl-BHPT, -BHPT and -BHPT, having Br-, Cl-, and substituents at the para position of the phenol hydroxyl group of H-BHPT were synthesized. Hydrochloric acid salts of 3OH-BHPT and 4OH-BHPT, having different position of the phenol hydroxyl group of H-BHPT were also synthesized. The synthesis of each ligand was confirmed by C. H. N. atomic analysis and NMR, NMR, UV-visible, and mass spectra. The calculated proton dissociation constants () of the phenol hydroxyl group and secondary amine group of the synthesized ligands showed five steps of the proton dissociations. The order of the overall proton dissociation constants () of the ligands was Br-BHPT < Cl-BHPT < H-BHPT < -BHPT < -BHPT. The order agreed with that of Hammett substituent constants (). However, dissociation steps of 3OH-BHPT were four and that of 4OH-BHPT was three. The calculated stability constants () between the ligands and transition metal ions agreed with the order of values of the ligands. The order of the stability constants between the transition metal ions with the synthesized ligands was Co(II) < Ni(II) < Cu(II) > Zn(II) > Cd(II) > Pb(II). The order agreed well with that of the Iriving-Williams.
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KEYWORD
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New pentadentate ligand, Overall proton dissociation constants, Stability constants
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