| In recent years,coordination polymers(CPs),also known as metal-organic frameworks(MOFs),have become more and more popular objects for many researchers because of their rich structure and properties.In this research work,4-(2-carboxyvinyl)benzoic acid(H2L)was selected as the organic ligand.Eight cases of metal-organic complexes with different structures were obtained by hydrothermal synthesis with different metal salts.{[Ln(L)1.5(H2O)2]·2H2O·2DMF}n(Ln=Gd?Dy and Eu)(1?2 and3)?{[Cd(L)2(Phen)]·(H2O)·(DMF)}n(4)?{[Zn(L)1.5(H2O)]·(DMF)}n(5)?{[Mn(L)(Phen)]·2DMF}n(6)?{[Ni(L)(4,4'-bipy)(H2O)2]·0.5DMF}n(7)and{[(Co)3(L)2(Phen)2]·2H2O·0.5DMF}n(8),and they were respectively characterized by elementary analysis,XRD,FT-IR,and TGA,etc.The whole research work includes:(1)Based on 4-(2-carboxyvinyl)benzoic acid(H2L)and lanthanide metal,three lanthanide metal organic complexes 1,2 and 3 were constructed by solvothermal method.The three complexes have similar crystal structures,all of which are triclinic,P-1 space group,with six coordination,and the center ion,such as Gd3+,is bridged in different directions by carboxylic acid groups on the ligand to form secondary building unit of Gd2(COO)2.The elementary SBU ring is connected by the L2-ligand,and finally forms a one-dimensional twisted wave band along the c axis,and a bridge connector,almost perpendicular to the wave band,is connected to another wave band at the same time.Therefore,a two-dimensional layer is formed,and the two-dimensional layers are further linked to constructe a 3D network structure.In addition,complex 3 was tested for fluorescence sensing.The results show that the complex 3 has good fluorescence selectivity and sensitivity to Fe3+and nitrobenzene molecules.It has excellent detection performance of high quenching constant,fast response and low detection limit.Its quenching constants are 5.412×103and 1.326×104L·mol-1respectively;the detection limits are 2.1×10-6and 3.44×10-4mol·L-1.In the range of 2 K to 300 K,with a field strength of 1000 Oe,complex 2 has antiferromagnetic properties.(2)Two cases of complexes 4 and 5 with different structures were synthesized by hydrothermal method using Cd(II)and Zn(II)and H2L ligands.Single crystal X-ray diffraction tests were performed on the two complexes.The results show that:complex 4belongs to the monoclinic system,and its space point group is P21/c,and the space structure of the metal center is a pentagonal double cone configuration.Complex 5 also belongs to the monoclinic system,and its space point group is C2/c.The space structure and coordination is similar with 4,the same pentagonal double cone configuration.The solid-state fluorescence test shows that the emission spectra of complexes 4 and 5 are blue-shifted compared to the emission spectra of the ligand.In the fluorescence sensing test,complex 4 shows high recognition and selectivity for Fe3+,Cr O42-,and Cr2O72-with high quenching constants(6.22×104,2.49×105,and 3.93×105L·mol-1,respectively)and lower detection limits(2.54×10-5,8.144×10-5and 2.86×10-5mol·L-1,respectively),the detection ability of anion Cr2O72-is higher than that of Cr O42-.In the test of dye adsorption properties,complex 5 shows the ability to adsorb MG dyes.After calculation,the adsorption amount of 10 mg of complex 5 is about 0.00316 mmol·g-1.(3)H2L and Mn(II),Ni(II)and Co(II)were used to construct three metal organic complexes of 6,7 and 8 by solvothermal method.The space point group of complex 6 is Cc,which has a three-dimensional frame structure.Complex 7 belongs to the trigonal crystal system,and its space point group is P3221,which has a simple two-dimensional structure.Complex 8 also belongs to the monoclinic system,and the space point group is C2/c.8 is a two-dimensional layered structure constructed by a secondary building unit containing trinuclear cobalt ions.The magnetic test results show that the metal ions of the three complexes all have antiferromagnetic coupling effects. |
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