Salen with two aza-crown ether pendants H2L1 and its analogues H2L2—H2L4 were successfully synthesized starting from benzo-10-aza-15-crown-5 (BN15C5) or morpholine. Their structures were characterized by IR, MS, 1H NMR and elemental analysis, and were confirmed by X-ray diffraction analysis of H2L1. Moreover, the saturated oxygen uptake of their cobalt(II) complexes CoL1—CoL4 in diethyleneglycol dimethyl ether was determined at dif-ferent temperature. The oxygenation contants (2OK) and thermodynamic parameters (腍 and 腟) were calculated. The modulation of O2-binding capabilities by pendant substituents were investigated as compared with the parent Schiff base complex CoL5 (CoSalen). The results indicate that the dioxygen affinities of CoL have been much more enhanced by aza-crown pendants than that by morpholino pendants, and the O2-binding capabilities of CoL1 and CoL2 with aza-crown pendants would also be enhanced by adding alkali metal cations.
Four polyether-bridged dihydroxamic acids transition-mental complexes were used as mimic hydrolytic enzyme model catalyzing carboxylic acid esters (PNPP)hydrolysis.The kinetics and the mechanism on PNPP hydrolysis catalyzed by these complexes were investigated.The kinetic mathematical model of PNPP cleavage catalyzed by these complexes was proposed.The results showed that the rate for the PNPP hydrolysis catalyzed by the complexes became larger as the increase of pH of the buffer solution and four complexes exhibited high activity in the PNPP catalytic hydrolysis.
