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).

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 시약 및 기기
  2.2. 다섯 자리 질소-산소(N3O2) 계 리간드의 합성
  2.3. 전위차적정 법에 의한 리간드의 양성자 단계해리상수측정
  2.4. 전위차적정 법에 의한 중금속(Ⅱ) 이온과의 안정도 상수 측정
 3. 결과 및 고찰
  3.1. 다섯 자리 N3O2계 리간드의 합성
  3.2. 전위차적정 법에 의한 리간드의 양성자 해리상수값 결정
  3.3. 전위차적정 법에 의한 리간드와 중금속(Ⅱ) 이온과의착물 안정도상수 값 결정
 4. 결 론
 참 고 문 헌

• 김선덕(대구대학교 자연과학대학 화학․응용화학과) | Sun Deuk Kim (Department of Chemistry and Applied Chemistry, Deagu University) Corresponding Author
• 이혜원(대구대학교 자연과학대학 화학․응용화학과) | Hye Won Lee (Department of Chemistry and Applied Chemistry, Deagu University)
• 설종민(대구대학교 자연과학대학 화학․응용화학과) | Jong Min Seol (Department of Chemistry and Applied Chemistry, Deagu University)