| In the construction of metal-organic frameworks in recent years,the compounds constructed with nitrogen heterocyclic monocarboxylic acids as ligands have attracted extensive research due to various coordination modes,strong coordination ability,applications in fields such as detection of substances,magnetism,adsorption and separation of gases and so on.Therefore,in this paper,six kinds of new metal-organic coordination polymersweresynthesizedbysolvothermalmethodwhich5-(1,2,4-triazol-4-yl)pyridine-3-carboxylic acid and 2-mercaptonicotinic acid were used as organic ligands,transition metal ions such as Zn(?)?Mn(?)?Cd(?)?Cu(?)and main group metal Pb(?)as metal centers.All the compounds were characterized by single crystal X-ray diffraction,elemental analysis,PXRD analysis,infrared spectroscopy,etc.,and some compounds were investigated for their fluorescence properties.The details are as follows:1.Five new coordination compounds{[Zn2(tynca)2(OH)(H2O)]·4H2O·NO2}n(1),[Mn(tynca)(H2O)3]n(2),[Pb(tynca)2]n(3),{[Cd2(tynca)(btc)(H2O)2]·3H2O}n(4),{[Zn2(tynca)(btc)(H2O)3]·H2O}n(5)have been obtained by reactions of the corresponding metal salts and 5-(1,2,4-triazol-4-yl)pyridine-3-carboxylic acid ligand under solvothermal conditions.Notably,in order to construct various compounds,we also introduced trimesic as the auxiliary during the construction of compounds 4-5.The structural of all the compounds showed that the central metal ions of complounds 1-5 coordinate with5-(1,2,4-triazol-4-yl)pyridine-3-carboxylic acid ligand or trimesic ligand in different modes,and five different two-dimensional structures were constructed.It indicated that synthesis conditions such as temperature,solvent selection and ratio,material ratio,and p H of the solution in the reaction process would affect the structure of the compounds,which influenced the coordination mode of metal ions and ligands and the steric configuration of the compounds.The fluorescence properties of compounds 3-5 in the solid state were carried out.Further,the high fluorescence performance of compound 4 was applyed for the detection of the metal cations and anions in water.The compound 4 displays sensitive luminescence quenching response to Fe3+,Cr O42-and Cr2O72-ions with detection limit of 3.51×10-6M,2.70×10-6M and 1.39×10-6M,respectively.2.One new coordination compound{[Cu3Zn(mna)3(en)2(H2O)]·H2O}n(6)has been obtained by reactions of Cu(I)+Zn(?)metal salts and 2-mercaptonicotinic acid ligand under solvothermal conditions.The structure analysis showed that compound 6 was a bimetallic organic compound.Each central metal Cu(I)ion in the structure was coordinated with the sulfur atom on the 2-mercaptonicotinic acid ligand to form a Cu6S6cluster structure.Then,bimetallic compound was further constucted by the oxygen atoms on the 2-mercaptonicotinic acid ligand was combined with Zn(II)ions.The fluorescence properties of compounds 6 has also been investigated,and the results showed that compound 6 had the largest emission peak at 729 nm under the excitation of 365 nm.It may be attributed to the presence of strong Cu-Cu interactions in the Cu6S6clusters contained in the structure and ligand-to-metal transition(LMCT). |
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