Metalloporphyrin Based Coordination Polymers As Heterogeneous Catalysts:Preparation And Characterization

The heterogenization of homogeneous metalloporphyrin(MP)is a development tendency for metalloporphyrin-based catalysts.Nowadays,metalloporphyrins are immobilized in the coordination polymers as metalloligands to form the metalloporphyrin-based coordination polymers(MPCPs)which are rapidly developing among strategies of the heterogenization.In this work,porphyrins bearing trazol-,tetrazol-and cyano substituents are chosen and metalized.Then,the metalloporphyrins as metalloligands and cuprous iodide clusters([CuxIy]x-y)as inorganic units,both of which are hybridized to form the MPCPs.The main work as follows:(1)Three metal free porphyrins,5,10,15,20-tetrakis(4-(1H-1,2,4-triazol-1-yl)phenyl)porphyrin(P1),5,10,15,20-tetrakis(4-(2H-tetrazol-5-yl)phenyl)porphyrin(P2)and 5,10,15,20-tetra(4-cyanophenyl)porphyrin(P3),were synthesized and characterized by UV-Vis,Mass,Elemental analysis and single crystal X-ray diffraction of their metalloporphyrins.Their infrared spectra were tested.(2)The suitable single crystals of MP1(M = Mn2+,MP1-1;Co2+,MP1-3;Cu2+,MP1-5;Zn2+,MP1-6;Ag2+,MP1-7),MnP2(MP2-1)and NiP3(MP3-4)were obtained via solvothermal,and characterized by single crystal X-ray diffraction.MP1-1,MP1-3,MP1-5,MP1-6 and MP1-7 are discrete compounds and possess similar structures in which the metal ions locate at the central of the porphyrins,coordinating to four nitrogen atoms from four pyrrole rings.MnP2(MP2-1)is distinct,it is 2D coordination polymer.Mn(IV)locate at the central of the porphyrins coordinating with six nitrogen atoms,four of which from four pyrrole rings in equatorial plane,the other two ones from the deprotonation tetrazole rings of adjacent two equivalent MnP2 at the axial direction of the distort octahedron.Finally,2D rhombus nets are formed in(101)plane,the sizes of the windows are 13.346 × 13.346 A2,and the solvent accessible volume is 27.4%in MnP2(MP2-1).The crystalline solid MP3-4 is an accumulation of "saddle" NiP3 molecules.By virtue of these metalloporphyrins,on one hand,the composition and structure of P1,P2,P3 and metalloporphyrins can be confirmed;on the other hand,their UV-Vis and IR spectra are the foundations based on which the formation of the others metalloporphyrins and MPCPs whose structure unknown could be speculated.The others MP1(M = Fe3+,MP1-2;Ni2+,MP1-4),MP2(M = Fe3+,MP2-2;Co2+,MP2-3;Ni2+,MP2-4;Cu2+,MP2-5;Zn2+,MP2-6;Ag+,MP2-7)and MP3(M = Mn3+,MP3-1;Fe3+,MP3-2;Co2+,MP3-3;Cu2+,MP3-5;Zn2+,MP3-6;Ag+,MP3-7)were synthesized by solution-based methods.They are characterized by UV-Vis,IR and EA analyses,and their formations are confirmed by combining the relevant data of known structures of the metalloporphyrins.(3)21 kinds of MPCPs were synthesized,i.e.MP1-CuI(M = Mn2+,MP1CP-1;Fe3+,MP1CP-2;Co2+,MP1CP-3;Ni2+,MP1CP-4;Cu2+,MP1CP-5;Zn2+,MP1CP-6;Ag2+,MP1CP-7),MP2-CuI(M = Mn3+,MP2CP-1;Fe3+,MP2CP-2;Co2+,MP2CP-3;Ni2+,MP2CP-4;Cu2+,MP2CP-5;Zn2+,MP2CP-6;Ag+,MP2CP-7)and MP3-CuI(M = Mn3+,MP3CP-1;Fe3+,MP3CP-2;Co2+,MP3CP-3;Ni2+,MP3CP-4;Cu2+,MP3CP-5;Zn2+,MP3CP-6;Ag+,MP3CP-7).They are characterized by UV-Vis,EDS,IR,powder XRD and TG-DSC analyses,and based on which the formation of the MPCPs are speculated.The metalloporphyrins bind to cuprous iodide clusters by coordination bonds,for which the isolation of metalloporphyrins active sites achieved.(4)To assess the catalytic properties of MP1CP-(1-7),MP2CP-(1-7)and MP3CP-(1-7),the oxidation of Ethylbenzene(EB),Propylbenzene(PB)and Diphenylmethane(DPM)were carried out using tert-Butyl hydroperoxide(TBHP)as the oxidant.It is confirmed that MP1CP-(1-7),MP2CP-(1-7)and MP3CP-(1-7)possess the catalytic activities to the alkylbenzene oxidation,and the activities are derived from metalloporphyrin sites.Compared with the corresponding metalloporphyrins,MP1CP-(1-7),MP2CP-(1-7)and MP3CP-(1-7)hardly any detectable metalloporphyrin leaching and decomposition in the oxidation of alkylbenzenes,suggests that metalloporphyrins bind to cuprous iodide clusters with coordination bonds and the active sites are insulated from each other,thereby avoiding the self-oxidation decomposition.This result shows that the way of hybridization of metalloporphyrins and cuprous iodide clusters for heterogeneous catalysts preparation,which could improve the stabilities of metalloporphyrins homogeneous catalysts.