Homochiral Coordination Polymers Based On Terephthalic Acid Ligands With Different Chiral Substituents

At the present day,chiral coordination polymers(CPs)have got universal attentions from researchers all over the world because of their great potential application in chiral recognition,isomer separation,asymmetric phase catalysis,fluorescence sensing,magnetism,and so on.In this paper,we synthesized three semi-rigid chiral dicarboxylic acid ligands in monosubstituted or disubstituted form by attaching L-alanine and L-proline to terephthaloyl groups.Under the guidance of crystal engineering,six new homochiral coordination polymer have been constructed,including 2D and 3D structure.The fluorescence,photocatalytic,dyes adsorption and guest molecules adsorption/desorption properties of some complexes were studied after the crystal structure analysis.The specific research work mainly includes the following three parts:1.Synthesis and characterization of coordination polymers based on bis-substituted chiral aminodiacetic acid ligands and Cd(?)ions:(1)The chiral ligand terephthaloyl-bis(L-alanine)(H2L1)has been obtained through amide condensation reaction and characterized by IR and 1H NMR.(2)Two complexes have been synthesized in the presence/absence of linear bipyridine auxiliary ligands:[Cd(L1)(bpea)(H20)]·3H2O·3DMF(1)and[Cd(L1)](2)(bpea =1,2-Di(4-pyridyl)ethane,DMF=N,N-Dimethylformamide).Complex 1 has a 3D structure in which exist right-handed helix chains(-Cdl-O5-C14-06-)n.Complex 2 possesses a 2D layered structure in which exist left-handed helix chains(-Cd1-05-)n.What's interesting,the oxygen atom of amide group in 2 takes participate in coordination.In addition,the differet structure of complexes 1-2 show that the ligand coordination mode and the N-donor auxiliary ligand have important effect on the structure of the coordination polymer.(3)Fluorescence tests indicate that complex 1 will be a potential luminescent material.The photocatalytic experiments show that both of these two complexes have some degradation effect on methylene blue.2.Synthesis and characterization of coordination polymers based on bis-substituted chiral aminodiacetic acid ligands and Co(?)/Ni(?)ions:(1)Two complexes with isomorphous structure have been synthesized by solvothermal or volatile methods using different bipyridyl auxiliary ligands:[Co(L1)(bpee)(H2O)2]·3H20(3)and[Ni(Ll)(bpea)(H20)2]·3H2O(4)(bpee = 1,2-bis(4-pyridyl)ethylene).Complex 3 displays a(4,4)grid 2D coordination network in which exist zigzag chains[Co(L1)]n and straight chains[Co(bpee)]n.Different synthetic conditions lead to the same crystal structure,which is detail analyzed and discussed in this paper.(2)Complexes 3 and 4 have the ability to photocatalytic degradate methylene blue,which effect is not as good as the first part.Moreover,complex 3 will be a potential dye adsorbent because of the effective adsorbsion for methyl orange which contains sulfonic acid groups.3.Synthesis and characterization of coordination polymers based on mono-substituted chiral aminodiacetic acid ligands and Cd(II)ions:(1)The chiral ligand terephthaloyl-mono(L-alanine)(H2L2)and terephthaloyl-mono-(L-proline)disodium salt(Na2L3)have been obtained through amide condensation reaction and characterized by IR and 1HNMR.(2)Two complexes have been synthesized through solvothermal or Layer method using linear or V-shaped auxiliary ligands:[Cd(L2)(bpipa-4)]·2H2O·CH3OH(5)and[Cd4(L3)4(bpea)6]·10H2O-4C2H5OH(6)(bpipa-4 = N,N'-bis(pyridin-4-yl)isophthala- mide).Complex 5 exhibits a(4,4)grid 2D coordination network in which exist small zigzag chains[Cd(L2)]n and large zigzag chain[Cd(bpipa-4)]n.Complex 6 features a triple-interspersed 3D structure with the characteristics of hexagonal boron nitride topology.Different shapes of auxiliary ligands play an effective role in regulating the structure of the complexes.(3)Fluorescence tests show that complex 5 will be a nice potential luminescent material.Both of these two complexes have little degradation effect on methylene blue.The thermogravimetric analysis and guest molecular desorption/desorption studies indicate that the framework of complex 5 is relatively stable and can be used as a material for reversible desorption/desorption guest molecules.