Porphyrin-based Transition Metal Coordination Polymers:Preparation,Characterization And Catalytic Performance

Porous coordination polymers(PCPs)have attracted wide attention in recent years,due to their unique structures and perfect properties.As a kind of functional materials,the porous coordination polymers have the dual characteristics of the organic polymer and inorganic metal.With metalloporphyrins as building unit,the porphyrin-based coordination polymers are hopeful for the applications in gas adsorption,molecular recognition,heterogeneous catalysis and so on.The porphyrins with peripheral pentafluorophenyl and carboxyl groups were designed as building units for porphyrin-based PCPs in the paper,and we hope the stable PCPs can be obtained and will have good properties in the aspects of gas adsorption and heterogeneous catalysis.Firstly,we synthesized four free porphyrins,named 5-(pentafluorophenyl)-10,15,20-tri-(4-methoxycarbonyl)phenylporphyrin(H2F5EPP),5,15-di-(pentafluorophenyl)-10,20-di-(4-methoxycarbonyl)phenylporphyrin(H2F10EPP),5-(pentafluorophenyl)-10,15,20-tri-(4-carboxy)phenylporphyrin(H2F10CPP),5,15-di-(pentafluorophenyl)-10,20-di-(4-carboxy)phenylporphyrin(H2F10CPP)and corresponding(Cu(?)n Zn(?)?Co(?)?Ni(?)?Mn(?)?Fe(?))metalloporphyrins.All the synthesized compounds were characterized by 1H NMR,mass spectra(MS),ultra violet-visible(UV-vis),foruier transform infrared(FT-IR)and elemental analyses(EA),and the crystal structures of Zn(F10EPP),Cu(F101EPP)and Co(FsEPP)were obtained and analyzed.Secondly,twenty-four porous coordination polymers(CP1-CP24)were synthesized solvothermally by the reactions of carboxylic-containing metalloporphyrins with transition metal salts(Co(?),Mn(?),Ni(?)).These porous coordination polymers were characterized by FT-IR,XRD,TGA,SEM,TEM and N2 adsorption.The TGA indicates that these coordination polymers are stable until 350?.The images of SEM,TEM show that they are all have regular morphologies and sizes,and the results of nitrogen adsorption experiment indicate that they have porous structures and a larger specific surface areas.Thirdly,the catalytic properties of these porous coordination polymers as heterogeneous catalysts were tested by the oxidation of ethylbenzene.The results reveal that all of these can catalyze efficiently the conversion of ethylbenzene to acetophenone with nearly 100%selectivity,and higher than the corresponding metalloporphyrins.In addition,their catalytic activities remain high after several repeats.These results could be useful for the further research that design new porous heterogeneous catalysts with highly activities.