Construction Of Novel Micro/Nano-reactors For Heterogeneous Catalysis Applications

The cellular environment can be regarded as a sophisticated reaction locus,where metabolic pathways take place with unsurpassed efficiency and specificity.As a long-standing goal of biosynthetic chemistry,the construction of micro-or nano-reactors that mimic the superior qualities of natural cells is highly desirable.These qualities often include the ability to operate in an aqueous solution,to provide a well-defined compartment for spatially isolated catalytic cycles and to select one substrate in light of its size or shape from a pool of structurally related molecules.In this thesis,the construction and catalytic application of micro-or nano-reactors are performed.1)A chiral molecular catalyst is encapsulated in the hollow silica nanoreactor by an in-situ polymerization method.In the aqueous phase asymmetry hydrogen transfer of aromatic ketones,the catalyst showed higher activity(TOF 991 vs 724 h^-1)and similar enantio-selectivity?94%ee?compared with its corresponding homogeneous catalyst.The high activity and selectivity of the catalyst are mainly attributed to its unique hydrophobic@hydrophilic surface properties and the freedom of the large molecular catalyst in the restricted domain.In addition,the encapsulated catalyst has better cycling performance than the single large molecular catalyst.2)According to the principle of"space isolation"of heterogeneous catalyst,we synthesized a yolk-shell nanomaterial with double pore diameter distribution.The nano-reactor effectively separates enzyme and metal nanoparticles so as to avoid mutual damage,which realize the precise positioning of these two active units.The catalyst obtained 98%conversion rate and 63%selectivity in the racemization of phenylethylamine.3)An organic-inorganic hybrid microcapsule reactor was fabricated by using the Pickering emulsion as the template and the organic polymerization reaction in theemulsion droplet internal.We control the permeability of the reactor by regulating the properties of Pickering emulsion interface particles and pore structure.The microporous structure of the surface provides the selective permeation function of similar cell membrane,which can realize the size selection of reaction substrate.The organic polymer of microcapsule inside provides a comfortable micro-environment for molecular catalyst,which can realize efficient operation of the reaction.In the water phase asymmetry hydrogen transfer of small-sized aromatic ketones,the solid catalyst showed similar catalytic activity with homogeneous Rh-VBSDPEN catalyst.Meanwhile,the solid catalyst also exhibited size selectivity to large-sized reactants.Our work provides an effective way to prepare multifunctional micro-nano reactors with size-selective properties and favorable catalysis microenvironments.