The Study Of Synthesis And Catalytic Performance Of A New Catalyst Cd Metallomacrocycle-keggin Type Heteropolyoxotungstates

Polyoxometalates (POMs) have popular research as industrial catalysts due to theirstrong acidity and redox properties. But the high solubility in polar solvent make it difficultto achieve in many multiphase systems catalysis and effective recovery. However, thetraditional methods of immobilization of POM lead to inactive of acid sites so that reducethe catalytic efficiency of POM and greatly limit their practical applications.Therefore, weprovide a new way to solve the above practical problems.Organometallic macrocyclic compounds are a class of macrocyclic supramolecularwith metal ion and an organic ligand. Since the pore size, shape nature and charge of thering are highly controlled by bridging ligands and the metal ion species, we selected a kindof metal-organic macrocycle with the appropriate internal aperture and charges to meet theneeds of POM, which utilize electrostatic force to build a new type of self-assembledcatalyst system that the POM are encapsuled or wrapped in the interior hollow of theMOMC.We design a polypyridine ligand with organic branch through the method of organicsynthesis. Then a polypyridine-Cd macrocycle was designed by ligand and cadmium nitratewhich is investigated by HNMS. The observations suggest that the product is puresix-member ring compound. We focused on the supermolecules Cd-MOMC@PW11Mcomprising of mono-transition-metal-substituted Keggin-type tungstophosphate[(n-C4H9)4N]4HPW11M(H2O)O39(M=CoII, NiII, CuII, ZnII) and Organometallic macrocyclic(MOMC), whose structures were fully investigated by IR, XRD, TG, MS. The results showthat the complex retains the structural identities of the two components.Finally oxidation catalytic activity of the Cd-MOMC@PW11M complex were assessedthrough the epoxidation of cyclooctene. Both we explore the solvent, reaction time, reactiontemperature and catalyst amount on the relationship between the experiment conditions andproduct. Compared with pure POMs, an enhanced oxidation catalytic activity of thecomplex is observed, which can be explained by the unique host-guest interaction betweenMOMC and organic substratescan put the organic molecules in close proximity to thecatalyst POMs. In addition, the catalytic reaction as heterogeneous catalysis, the catalystcould be recovery easily and recycling without obvious loss of activity. And at the end ofthe catalytic experiment, the structure of the catalyst remained stable.