Three new crowned bis-Schiff bases, 4',5'-bis(2- hydroxyphenylmethylideneimino)benzo-12-crown- 4(L^1H2),4',5'-bis(5- chloro-2-hydroxyphenylmethylideneimino) benzo-12-crown-4(L^2H2),4',5'- bis(5-bromo-2- hydroxyphenylmethylideneimino)benzo-12-crown-4(L^3H2) and their cobalt(Ⅱ) complexes(1,2,3) were prepared and characterized by MS,IR, NMR and elemental analysis. The stoichiometries of dioxygen uptake by the Co complexes were measured in pyridine solution. The equilibrium constants and thermodynamic parameters of oxygenation (△H°, △S°) were calculated. The catalytic activity and selectrivity of the cobalt complexes in cyclohexene oxidation were examined. The influence of the crown ether ring on dioxygen affinity of the Co complexes and on the catalytic activity are discussed in comparing with uncrowned analogues complexes.

Key words: CROWN ETHER, SCHIFF BASE, COBALT COMPLEX, CATALYTIC OXIDATION, CATALYTIC ACTIVITY