| In recent years,metal-organic frameworks(MOFs)as a new class of functional materials have attracted considerable attention not only because of their fascinating structural architectures and novel topologies but also due to their potential applications in gas storage/separation,chemical sensing,optics,magnetism and so on.Many studies on the construction of MOFs have been carried out,especially those with mixed N-donor and multicarboxylate ligands.Although a great progress has been achieved,it is still a challenge to rational design and synthesize MOFs with desired structures and properties.Because the structures of MOFs can be affected by many factors.Therefore,in order to further understand the self-assembly process,systematic studies on the factors that influence on the structures of MOFs are important.In this dissertation,18 new MOFs were synthesized based on three different rigid 1H-imidazol-4-yl containing ligands,namely 1,3-di(1H-imidazol-4-yl)benzene(L~1),1,4-di(1H-imidazol-4-yl)benzene(L~2),4,4'-di(1H-imidazol-4-yl)biphenyl(L~3)together with a series of multicarboxylic acids to react with transition metal salts under solvothermal/hydrothermal conditions.The influence of metal center,auxiliary ligand and reaction solvent on the structures and properties of the MOFs were investigated.There are four parts in this thesis:1.Reactions of L~1/L~2 and 1,3,5-tri(4-carboxyphenyl)benzene(H3BTB)with transition metal salts gave five new MOFs[Ni3(L~1)4(BTB)2(C2H5OH)2(H2O)6]· 3H2O(1),[Ni3(L~1)4(BTB)2(H2O)8]·8H2O(2),[Cd3(L~1)2(BTB)2(H2O)]·DMF·H2O(3)(DMF = N,N-dimethylformamide),[Ni3(L~2)3(BTB)2(H2O)6]·4H2O(4)and[Cd3(L~2)3(BTB)2]·H3BTB·H2O(5).1 and 2 are infinite one-dimensional(1D)chains,4 and 5 are two-dimensional(2D)networks,which are further linked together by hydrogen bonds to give eventual three-dimensional(3D)architectures,while 3 is a 3D framework.The results imply that the solvent system and metal center have subtle but important influence on the structure of the complexes.Fluorescent sensing and selectively adsorption,SHG activity and ferroelectric properties of the complexes were investigated.2.By using L~1 and multicarboxylate ligand H3BTB to react with corresponding Co(?)and Cd(?)salts under solvothermal conditions,two new MOFs[CO4(?3-OH)2(L~1)(BTB)2(H2O)3]·5.6H2O(6)and[Cd3(L~1)2(BTB)2(?2-H2O)]·7.4H2O(7)were successfully obtained.6 possesses(3,7)-connected bi-nodal 3D framework with Schlafli symbol of {4·62}2{42·616·83}.7 possesses(3,4,8)-connected 3-nodal 3D framework with Schlafli symbol of{4·62}2{42·63·7}{44·614·73·86·10}.Photoluminescence,magnetic and sorption properties were investigated.Selective and hysteretic sorption of CO2 over N2 was found for 6 and 7.The results of adsorption for dye molecules illustrated that 6 and 7 could selectively adsorpt methyl orange molecules.Meanwhile,magnetic measurements revealed that there are antiferromagnetic interactions between the Co(?)ions within the tetranuclear cluster in 6,and 7 can be considered as a potential luminescent probe for detection of acetone,cyclohexanone,acetophenone and benzophenone molecules.3.Five new MOFs[Zn(L~2)(bpdc)]·1.6H2O(8),[Ni(L~2)(bpdc)](9),[Co(L~2)(bpdc)]H2O(10),[Ni3(L~2)2(bptc)2(H2O)10]· 2H2O(11)and[Cd2(L~2)(Hbptc)2](12)(H2bpdc=4,4'-benzophenonedicarboxylic acid,H3bptc = biphenyl-2,4',5-tricarboxylic acid)were synthesized by assembly of L~2,H2bpdc,H3bptc with transition metal salts.Both 8 and 9 possesse 4-connected 3D framework with Schlafli symbol of(65·8),10 is an infinite 1D chain,11 is 2D network,which are further linked together by hydrogen bonds to give eventual 3D architectures,while 12 is a(4,5)-connected bi-nodal 3D framework with Schlafli symbol of{43·63}{43·66·8}.The influence of metal center,auxiliary ligand on the structures and properties of the complexes was investigated.In addition,the gas sorption properties of 8 and sensing properties of 8 and 12 were studied.8 and 12 can be considered as a potential candidate for selective sensing of acetone,cyclohexanone,4-heptanone,5-nonanone molecules and Fe(?)ions.4.Six novel MOFs[Cd(L~1)(oba)]·DMF(13),Ni3(L~1)2(BPT)2(H2O)4(14),[Zn2(L~1)2(HBPT)2]H2O(15),Ni(L~1)(BPTC)0.5(H2O)2(16),Ni2(?2-O)(L~3)2(oba)2(H2O)2(17)and[Ni2(L~3)3(BPTC)(H2O)2]·6H20(18)(H2oba = 4,4'-oxydibenzoic acid,H3BPT ?biphenyl-3,4',5-tricarboxylic acid,H4BPTC = biphenyl-3,3',5,5'-tetracarboxylic acid)were prepared by solvothermal reactions of L~1/L~3,H2oba,H3BPT,H4BPTC with correspnding metal salts.13,15,16 and 17 are 2D networks,14 is(4,4)-connected bi-nodal 3D framework with Schlafli symbol of {3·4·5·83}4{32·82·92},while 18 is a porous 3D framework.The influence of metal center,ligand on the structures and properties of the complexes was examined.In addition,the gas sorption and sensing properties of MOFs were studied.Selective and hysteretic sorption of CO2 over N2 was found for 18.13 and 15 can be considered as a potential candidate for selective sensing of acetone molecules and Fe(?)ions. |
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