Synthesis Of Calixarene-Hydroxamic Acid And The Properties Of Their Transition Metal Complexes As Artificial Model Of Monooxygenase

The study of biomimetic oxygen carriers is important to reveal the mechanism of reversible bonding, activating oxygen and the oxidation reaction in organism, and to realize the separation and enrichment of oxygen, high efficiency and selectivity of catalytic oxidation under a moderate condition. We design and synthesize a kind of new mimetic monooxygenase using calixarene as the recognition site and hydroxamate as the catalytic site. The further investigation is aimed at the influence of calixarene and it's the bonding fashion on the dioxygen-affmities, biomimetic catalytic oxidation performance.We synthesize a series of calix[4]arene hanging double-wing hydroxamates H2Ln(n=1-3), single-wing hydroxamate HL4 and their metal complexes via etherification, hydrolysis, condensation from the calix[4]arene, among which 7 new compounds were unreported and characterized by IR, 1H NMR, MS and elemental analysis. The oxygenation performance of cobalt(11) hydroxmate bearing calixarene residue was investigated, it's equilibrium constants K02 and thermodynamic constants H, S for oxygenation in the pyridine solution were determined. Compared with simple hydroxamate complex CoL25, complexes bonding with calixarene hydrophobic cavity can improve the dioxygen -affinities.The monooxygenase mimicking performance of manganese(III) complexes MnL2Cl was first checked, with PhIO as the oxygen source. This complex was achieved in the catalytic epoxidation of styrene under the ambient temperature andpressure. The influence of axis ligands (pyridine, imidazole, ethylene glycol dimethyl ether) on epoxidation of styrene were examined and the active of these axis ligands decrease in the order imidazole>> ethylene glycol dimethyl ether > pyridene; The catalyst MnL2 with calixa[4]rene as recognition site has better conversion (more than 25%) in comparison with simple manganese hydroxamate(MnL25Cl)and it's selectivity is close to 90% in the catalytic epoxidation.With the dominant energy conformation diagrams for the ligands, we can get the reasonable explanation for the effects of ligand structures on the complexation ability and biomimetic catalytic performance.