Synthesis, Characterization And Properties Of Co(Salen) Based Bimetallic Complexes

In recent years,modification of the structures of M-Salen complexes,to change the asymmetric catalytic environment of the active center of the catalyst,has been gaining more attention.Although those of M-Salen complexes are nonenzymatic asymmetric catalyst,they can maintain the recognition with substrates effectively and get high level of enantiomers excess in asymmetric catalytic reaction.These efficient catalytic substrate orientation reaction including rubidium catalyzed asymmetric hydrogenation,Noyori Ru(BINAP) catalyzed hydrogenation of functional-alkene and ketone,the corresponding alkene isomerization epoxidation,asymmetric ring-opening of epoxides,hydrolytic kinetic resolution of terminal epoxides.Since homo- or hetero-bimetal complexes have different coordination structures with mononuclear complexes,they show some interesting properties:the co-existence of bimetallic active center can promote multi-electronical redox reactions;moreover multidentate ligand and chelating bimetal centers can integrate such bimetal catalytic units;in addition,high and low spin exchange of outer electrons resulted by the interaction of adjacent metal centers will lead the complex to show ferromagnetism or antiferromagnetism.Particularly,most of 3d-4f heterometal complexes have good magnetic properties.The factor that fluorescence of f-f electron transition of rare-earth ion can be almost completely quenched by adjacent transition metal ion proves that transition metal ion can transfer the energy generated by excited rare-earth ion very well.This propertity is very important in the studies of molecular wires, molecular switches and other electronic devices.We synthesized a series of Co(salen) derivatives and studied their reaction with transition metal ions like Co~â…¡,Mn~â…¡and 4f rare-earth metal ions like Nd~â…¢,Sm~â…¢,Eu~â…¢, Tb~â…¢,Er~â…¢,Yb~â…¢.The produced bimetal complexes were characterized by single crystal X-ray diffraction and IR.In the meantime,we studied catalytic properties,magnetic properties and photophysical performance of these complexes as well.In addition,we also studied the reaction of Co(salen) with TCNQ(7,7,8,8,-tetracyanoquinodimethane) which afforded a coordination polymer.This product has a wide range of applications in magnetic materials.