Syntheses And Properties Of Metal Imidazolate Frameworks

Imidazole is a molecule with five-membered ring which including two meta-position N atoms.It possesses important applications in the realm of biological medicine,pesticide and the synthesis of epoxy curing agent.Due to the similar angle between the two N donors(140°)in imidazole and Si-O-Si(145°)in zeolite,synthesis of metal imidazolate complexes could not only rich the structural types but also reach to design some zeolitic imidazolate frameworks with certain pore size,high surface area,low density and price.Inorganic chemists express great interest in constructing such kind of zeolitic imidazolate frameworks.In this thesis,we get a series of new metal imidazolate complexes by using transition metal ion(Co,Ag,Cd)and imidazolate ligands.Meanwhile,catalytic and fluorescence properties of some of these compounds were investigated.Here,we divide these 10 coordination polymers into 4 groups:(1)Complexes 1-3 are metal boron imidazolate cages templated by anions;(2)Complexes 4-7 are metal boron imidazolate frameworks constructed by Ag(I)and tridentate boron imidazolate compounds;(3)Complex 8 is a 4-conected zeolitic framework constructed by Cd(?)and quadridentate boron imidazolate compound;(4)Complexes 9-10 are chain-like structures constructed by Ag(?)and imidazole ligands.This dissertation was divided into four chapters:Chapter one is introduction.We briefly introduce the design ideas,structures and properties of some typical complexes in this field.Meanwhile,we define our research objective and significance.In the second chapter,we focus on experimantal details including materials,instruments and synthesis.The third chapter covers structural characterization and property study of metal complexes based on imidazolate ligands.Main results are summarized as follows:1.Pre-synthesized tridentate boron imidazolate ligand KBH(bim)3 and transition metal center Co(II)were used as raw materials and three metal boron imidazolate cages with different configuration(cubic M4L4 cage:{Co4[BH(bim)3]4(OH)3(H2O)}·X(X= Br,I)(1);trigonal bipyramid M5L6 cage:{Co5[BH(bim)3]6Cl2(H2O)4(X)2}·CI2(X=DMF,DEF,H2O)(2);rhombic dodecahedron M6L8 cage:{Co6[BH(bim)3]8(H2O)12}4+(3))were obtained through the control of different cobalt salts(CoCl2·6H2O,CoBr2·xH2O,Co(NO3)2·6H2O).In complexes 1 and 2,halogen ions which act as template and charge balancing agents were encapsulated in cages.Complex 2 could transfer to complex 1 through solvothermal method by introducing KBr or KI into reaction system.In addition,all three complexes could be acted as co-catalysts for catalytic reduction of CO2 to CO under visible light.2.Different pre-synthesized tridentate boron imidazolate ligands[KBH(im)3,KBH(mim)3,KBH(bim)3]and Ag2SO4 were used as raw materials and four new metal imidazolate complexes(Ag[BH(im)3](4);Ag[BH(mim)3](5);Ag[BH(bim)3](6);Ag3[BH(bim)3]2+(7))were obtained by using solventhermal and volatilization method.PXRD and TGA of these complexes were also investigated.3.Cd(CH3COO)2 and pre-synthesized quadridentate boron imidazolate lingand KB(im)4 were used as raw materials and a 4-connected zeolitic structure with ABW topology([Cd(CH3COO)B(im)4]·DMF(8))was obtained.In this complex,each Cd(II)center is chelated by an acetate to construct a distorted tetrahedral[Cd(ac)]+secondary building unit.The alternately link of[Cd(ac)]+ and B(im)4-create the zeolitic topology.This work further demonstrated the generality of the synthetic strategy.In addition,complex 8 could be regarded as a luminescent probe for testing nitrobenzene.Meanwhile,it can act as a substrate for loading of Ag nanoparticles,and the resulting samples display good catalytic performance.4.Ag2SO4 and 5,6-dimethylbenzimidazole,2-methylimidazole were chosen as raw materials and two chain-like coordination polymers(Ag(dmbim)(9)and Ag(mbim)(10))with promising fluorescence property were obtained through solventhermal method.In complex 9,two 21 helical chains were perpendicular to each other and showed obvious Ag…Ag(2.986 A)interactions which play an important role in mechanochromism.While,simple zigzag chains were found in complex 10.Because of the different position of the methyl group in the two ligands,the steric effects led to distinct structural disparity.In the last part,a brief conclusion and an outlook on this work are presented.