Construction And Properties Of Metal Complexes Based On 1H-Imidazol-1-yl-Containing Ligands

Coordination polymers as a new class of functional material have attracted considerable attention not only due to their fascinating structural architectures and novel topologies but also because of their potential applications in optics,magnetism,gas/solvent storage and separation,catalysis,drug release,and so on.Many studies on the construction of functional materials have been carried out,especially those with the N-donor and multicarboxylate ligands.Recently,the mixed ligand strategy has been widely utilized in the construction of functional coordination polymers.A number of coordination polymers have been obtained by using different synthetic methods and strategies,attempting to open out the relationship between structure and property so that achieving the functional targeted goal.However,the self-assembly of coordination polymers is seriously affected by some factors such as the geometry of metal center,the coordination ability and size of anion,reaction temperature,solvent,pH,the ratio of reactants,etc.In this thesis,25 new coordination polymers were synthesized by layering and solvothermal methods.Three imidazole-containing ligands 3,5-di(imidazol-1-yl)pyridine(L1),1,3,5-tris(imidazol-1-ylmethyl)benzene(L2)and 3,3',5,5'-tetra(imidazol-1-yl)-1,1'-biphenyl(L3)were used to reaction with metal salts and combination with auxiliary multicarboxylate ligands.The influence of metal center,anion,reaction condition and the auxiliary ligands on the structures and properties of the complexes were investigated.There are four parts in this thesis:1.We successfully prepared six new coordination complexes by layering method using L1 ligand,namely[Ni(L1)(H2O)3(SO4)](1),[Cu3(L1)4(H2O)2(SO4)](SO4)2·30H2O(2),[Cu(L1)2(H2O)2](NO3)2(3),[Cu(L1)2](ClO4)2(4),[Cd(L1)2(H2O)2](ClO4)2(5)and[Cd(Ll)(OAc)2(H2O)](6).Complex 1 is 1D zigzag chain,2 is a trinodal(3,4,4)-connected 3D framework,3 possess 1D hinged chain,4 and 5 show the same 2D network,while 6 is a linear chain.The results show that metal centers with different coordination numbers and geometries,counteranions with different coordination abilities and ligands with varied coordination modes play important roles in determining the structures of the complexes.Meanwhile L1 exhibits three kinds of coordination modes in these compounds owing to the discrepancy of coordination abilities between the pyridine and imidazole group.Furthermore,the photoluminescence and anion exchange properties of the complexes were investigated.2.Six new metal complexes of[Zn3(L2)2(BTC)2]·6H2O(7),[Zn3(L2)(BTC)2](8),[Cd3(L2)(BTC)2](9),[Cd3(L3)(BTC)2]·4H20(10),[Cd3(L3)(BTC)2(H20)2](11),[Zn2(L3)(BTC)(NO3)]·H2O·2CH3CN(12)have been successfully synthesized by solvothermal reactions of Zn(?)/Cd(?)salts with 1,3,5-benzenetricarboxylic acid(H3BTC)and imidazole-containing ligands of L2 and L3.H3BTC is completely deprotonated to give BTC3-in these compounds.In 7,BTC3-ligands bond with Zn(II)to give 2D network which are linked together by L2 ligands to generate the final 3D framework.Complexes 8 and 9 are isostructural,Zn(?)-BTC3-and Cd(?)-BTC3-themselves are 3D structures and L2 coordinated with metal centers filling into Zn(?)-BTC3-and Cd(?)-BTC3-.For 10,L3 ligands link Cd(?)to form 2D network and then connected by BTC3-to give rise to the 3D framework.In case of 11,L3 ligands combined with the two carboxylate groups of BTC3-coordinate with Cd(?)to form 2D network and further linked by the rest carboxylate group of BTC3-to form 3D structure.While,12 possesses 4-nodal 3,3,4,4-connected 2-fold interpenetrating 3D net and the anion takes part in coordination.The results confirm that reaction temperature,solvent system,the metal center as well as the flexibility and coordination number of organic ligand have subtle but important influence on the structure of the complexes.Meanwhile we investigated the photoluminescence property of these compounds and gas/vapor sorption properties of complexes 7,10 and 12.3.Seven novel metal complexes[Co2(L3)(HBTC)2(?2-H2O)(H2O)2]· 3H2O(13),[Co3(L3)2(BTC)2]·4H20(14),[Co2(L3)(BTC)?2-OH)(H20)2]·2H20(15),[Ni2(L3)(H20)3(HBTC)2]·3.6H20(16),[Ni(L3)(H20)2](BPDC)·2H20(17),[Ni(L3)(H20)(BPDC)]·4H20(18),[Ni2(L3)(MeOH)4(BPDC)2]·2H20(19)(H2BPDC =4,4'-biphenyldicarboxylic acid)have been obtanied by solvothermal reactions of L3 and the carboxylate ligands with Co(?)/Ni(?)salts under different conditions.13-15 with diffent structures were tuned by the reaction pH.Controlling the pH value of the solution can lead to variation in the degree of deprotonation and an introduction of a hydroxide group in 15.In 13,the Co(?)-L3 chains are connected together through the carboxylate group of HBTC2-and bridging H20 molecules to form 2D network.In case of 14,the combination of layers of Co(?)-L3 and Co(?)-BTC3-is still 2D network.For 15,the double-layer constructed by L3,OH-and Co(?)are further linked together by BTC-to form the final 3D framework.16 and 13 are isostructural.17-19 obtained by adjusting the ratio of reactants show different 2D networks.Interestingly,among these compounds,the number of carboxylate groups of BPDC2-participating in coordination is 0,1 and 2,respectively.The results show that factors referring to pH and the ratio of the starting materials have influence on the structure of the resulted coordination polymers.Meanwhile,we investigated the sorption properties of 13,14,16 and 18.13 and 16 have highly selective adsorption for H2O over MeOH and EtOH,at the same time,14 and 18 have the uptake capacity of H2O,MeOH and EtOH indicating their potential applications in vapor storage and separation.4.Six new coordination polymers were obtained by reactions of Zn(II)salts with L3 ligand and corresponding dicarboxylic acids,[Zn2(L3)(o-BDC)2](20),[Zn2(L3)(m-BDC)2]·4H2O(21),[Zn2(L3)(p-BDC)2]·2MeOH-4H20(22),[Zn2(L3)(BPDC)2]·H20(23),[Zn2(L3)(BPnDC)2]·6H20(24),[Zn2(L3)(OBA)2]·6H20(25)(o-H2BDC = phthalic acid,m-H2BDC = isophthalic acid,p-H2BDC = terephthalic acid,H2BPDC =4,4'-biphenyldicarboxylic acid,H2BPnDC = 4,4'-carbonyldibenzoic acid,H2OBA =4,4'-oxidibenzoic acid).All of these compunds are binodal(4,4)-connected 3D nets.20 has non-penetrating mot topology,21 possesses 2-fold interpenetrating bbf topology,while 22 shows 3-fold interpenetrating sta topology.In case of 23-25,they are 2-fold interpenetrating 3D nets with new topologies.Complexes 20,21,24 and 25 are 3D frameworks with infinite Zn(II)-L3 layer strucutres pillared by dicarboxylate ligands,in addition,24 and 25 are isostructural.In 22,the layers formed by L3,partial p-BDC2-and Zn(II),then pillared by the rest p-BDC2-.In case of 23,there are left-handed helical chains linked by Zn(II)-N bonds to form layer structure and then connected by BPDC2-to provide the 3D framework.This work indicates that the angle and length of dicarboxylic acids play important roles on the construction of complexes with diverse structures.We investigated the photoluminescence property of these compounds as well as the sorption properties of 21,24 and 25.All of them have no capacity of uptake N2,but sho-w adsorption capacities for H2O/MeOH/EtOH,flexible frameworks endowing the complexes with stepwise and hysteresis adsorption.