Nanoreactors cooperative activation effect

In this chapter, we summarize the recent advances in the development of nanaoreactors based on porous solid materials for chemical reactions, including the general methods for the fabrication of typical porous materials, (mesoporous silicas (MSs), carbon nanotubes (CNTs), and the MOFs), the assembly of the molecular catalysts in the cavities and pores of the porous materials, the chemical reactions in the porous-material-based nanoreactors, and some important issues concerning the porous-material-based nanoreactor, such as the pore confinement effect, the isolation effect, and the cooperative activation effect We close this chapter with an outlook of the future development of the nanoreactors. 

Through covalent and noncovalent bonding methods, different kinds of molecular catalysts could be incorporated into MSs and MOFs. These porous materials with the incorporated molecular catalyst could catalyze various kinds of chemical reactions. A review of all the related works is impossible and not necessary in this chapter. We only review some representative examples for demonstrating the unique properties of the nanoreactor for catalytic reactions, including the pore confinement effect, the enhanced cooperative activation effect, and the isolation effect, as well as the microenvironment and the porous structure engineering of the nanoreactor and the catalytic nanoreactor engineering. 

Mechanistic study shows that the high activity of the catalyst is mainly derived from the enhanced cooperative activation effect and the enrichment of reactants in the nanoreactor (Scheme 10.20b). This result strongly confirms the cooperative activation effect in the asymmetric reaction and is corroborated by a DFT calculation that the activation energy could be greatly reduced when the reaction goes through a bimolecular activation pathway (Scheme 10.22) [104]. 

In addition to the enhanced cooperative activation effect of the nanoreactor, the isolation effect could also be expected in the confined nanospace if the diameter of nanopore is similar to the size of the molecular catalysts, because the limited nanospace could restrict the free movement of the molecular catalysts. Two issues relevant to the isolation effect of the nanoreactor, namely selectivity control in organic reactions and inhibition dimerization of the molecular catalysts, will be discussed. 

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