ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 47, Number 6
JKCSEZ 47(6)
December 20, 2003 

Ligands, Br-PEMP, Cl-PEMP and CH₃O-PEMP having Br, Cl and CH₃O substituents at 5-position of the N₂O tridentate ligand, 2-[(2-pyridine-2-ethylamio)-methyl]-phenol (H-PEMP) containing pyridine and phenol were synthesized. Another ligand, Naph-PEMP having pyridine and 2-hydroxy-1-naphthalene was also synthesized. The ligands were characterized using elemental analysis, UV-visible, IR, ¹H NMR and ¹³C NMR spectroscopy and mass analysis. The potentiometric titration study in aqueous solution revealed that the proton dissociation of the ligands occurred in three steps and the order of overall proton dissociation constants (logβ) was CH₃O-PEMP > Naph-PEMP > H-PEMP > Cl-PEMP > Br-PEMP. The order of stability constants (logML and logML2) of their transition metal complexes was Co(II) < Ni(II) < Cu(II) > Zn(II). The order in their stability constants values of each transition metal complex agreed well with that in overall proton dissociation constant value of the ligands.