| Metal organic frameworks with multiple luminescence emissions under single-wavelength excitation has a good deal of important advantages to fluorescent sensors with single luminescence emission,such as high sensitivity,multiple-target detection and self-reference for environment-free interferences.Therefore,ML-MOFs has potential value in the fields of chemical detection.In this thesis,multiple-metal MOFs were constructed by organic ligand containing both carboxylic acid groups and pyridine rings with rare earth metal ions Ln3+and copper(?)halide clusters.The synthesis and luminescence properties of ML-MOFs were also studied.There are four chapters in this thesis.The first chapter is the introduction.The second and third chapters are the main contents of this thesis.The fourth chapter is the conclusion and prospect.In the first chapter,the related theoretical knowledge of LMOFs,the design strategy of constructing ML-MOFs,the related theoretical knowledge of LMOFs based on copper(?)halide cluster as secondary building units are introduced.In the second chapter,four ML-MOFs containing cuprous-halide clusters and Ln3+,namely[Eu2(Cu8I8)(C12H9O2N2O2)6(H2O)3(C4H8O2)]·4C4H8O2(1),[Gd2(Cu8I8)(C12H9O2N2O2)(H2O)3(C4H8O2)]·4C4H8O2(2),[Eu2(Cu8I8)(C12H9O2N2O2)6(H2O)3](3)and[Gd2(Cu8I8)(C12H9O2N2O2)6(H2O)3](4),were synthesized by solvothermal reactions using 3-amino-5-(pyridine-4-yl)benzoic acid as organic ligand.The four coordination compounds all have three-dimensional porous structure.The single-crystal to single-crystal phase transition from compound 1to compound 3 leads to fluorescence quenching.So far,Compound 3 is the fluorescence chemosensor for the detection of methanol based on a light recovery mechanism along with single-crystal to single-crystal phase transition.In the third chapter,three isostructural ML-MOFs containing cuprous-halide clustersandLn3+,namely[Eu2(Cu4I4)(C12H8NO2)4(C8H4O4)2]·2(C2H8N)2·2(C3H7NO)·2(H2O)(5)?[Tb2(Cu4I4)(C12H8NO2)4(C8H4O4)2]·2(C2H8N)2·2(C3H7NO)·2(H2O)(6)and[Gd2(Cu4I4)(C12H8NO2)4(C8H4O4)2]·2(C2H8N)2·2(C3H7NO)·2(H2O)(7),were synthesized by solvothermal reactions using 3-(pyridine-4-yl)benzoic acid and terephthalic acid as organic ligands.The three compounds exhibit excellent photoluminescence properties at room temperature.The emission maximum of compound 7 appears red-shift at low temperature.Moreover,two isostructural ML-MOFs containing cuprous-halide clusters and Ln3+,namely[Eu2(Cu I)3(C14H8N2O5)3(H2O)3]·3C4H8O2(8)and[Gd2(Cu I)3(C14H8N2O5)3(H2O)3]·3C4H8O2(9),were synthesized by solvothermal reactions using 5-(Isonicotinoylamino)isophthalic acid as organic ligand.Compound 8and 9 have non-luminescence at room temperatures.However,the luminescence of compound 8 and 9 began to recover belong with the decrease of temperature.Compound 8 and 9 are the ML-MOFs-based luminescent thermometers based on fluorescence“turn-on”mechanism.In the last chapter,we make a summary and prospect of this thesis. |
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