Microporous Chiral Catalytic Materials

The individual chemical species with chiral catalytic properties, such as complex, organometallic compounds, organic ligands or molecules, anchored or grafted into the channels of microporous and mesoporous materials, and some microporous compounds possessing chiral channels or their pore structures composed of the chiral motifs, all promise further development and potential application in microporous chiral (asymmetric) catalysis and separations. It is an important frontier direction in the zeolite catalytic field at present. Therefore, the synthesis and assembly of chiral microporous compounds and materials are of particular interest for researchers engaged in porous materials. This is a research field in rapid development. 

Assembly of Chiral Catalytic Centers in the Pores (Microporous and Mesoporous) of Molecular Sieves 

Example 1 Chiral rhodium complexes anchored on modified USY zeolites.[70] For the asymmetric catalytic hydrogenation reaction of iV-acylphenylaniline, the product not only has high translation yield and ee% value ( 95%), but also has a long reaction life. The assembly process of rhodium complex catalyser is as follows  

First step L-Proline as the chelate agent to prepare Rh+ complex. 

Second step The preparation of extra-stable Y-type zeolite USY with more surface Si OH groups. NH4Y zeolite was calcined at 1000 °C for 2h, followed by the surface treatment of dealuminum and hydroxidation by citric acid at 130 °C to obtain USY (pore size 15 A) with surface Si—OH groups. 

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Chemistry of Zeolites and Related Porous Materials 4.1.8 Microporous Chiral Catalytic Materials... 

Apart from the above described chiral porous assembly materials, zeolites with chiral structural features, i.e., helical channel structure, the channels of microporous materials are composed of chiral motifs, have been continuously studied by researchers in an attempt to explore microporous chiral catalytic materials. 

In certain forms of the material, the microporous polymer creates exactly two distinct, interwoven but disconnected porespace labyrinths, separated by a continuous polymeric dividing wall. This opens up the possibility of performing enzymatic, catalytic or photosyndietic reactions in controlled, ultrafinely microporous polymeric materials with the prevention of recombination of the reaction products by their division into the two labyrinths. These features combine with specific surface areas for reaction on the order of lO -lO square meters per gram, and with the possibility of readily controllable chirality and porewall surface characteristics of the two labyrinths. 

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