Complexation study on the Cu(II) complexes of ligands 13-(2'-hydroxyl)-substituted benzyl-1, 4, 8, 11-tetraazacyclotetradecane-12, 14-dione has been carried out by pH potentiometric titration at 25℃, I=0.10mol.cm^-^3 (KNO3). The protonation constants of ligands and the formation constants of complexes were obtained. The coordination form of ligands with copper(II) and the stability of complexes were discussed. A kinetic study of acid-induced decomposition for these ligands' Cu(II) ocmplexes has also been investigated, in which reaction mechanism was postulated, and the rate constants were calculated. The results show there exists LFER between equilibrium constants of complexes and protonation constants of ligands. Good Bronsted-type LFER between rate constants and equilibrium constants of complexes has also been found. The effects of macrocyclic substitutents on the formation and the decomposition of complexes were also discussed.

Key words: SPECTROPHOTOMETRY, REACTION MECHANISM, NITROGEN HETEROCYCLICS, COPPER COMPLEX, REACTION RATE CONSTANT