| Metal-Organic Frameworks?MOFs?are a series of crystalline porous structures with periodic network structures formed by the self-assembly of inorganic metal centers?metal ions or metal clusters?and bridged organic ligands.material.The MOFs network contains metal points,organic functional groups and adjustable structures,which show important application prospects in term of luminescence,adsorption and magnetism respectively.This article is designed to synthesize functional MOFs from three aspects.First,in order to find the new synthetic approaches and design strateges for function-oriented MOFs,metal ions(Co2+,Cd2+,Mn2+,Zn2+,La3+,Nd3+,Sm3+,Eu3+,Gd3+,Tb3+,Dy3+,Er3+,Tm3+)as the metal center of the structure,flexible polycarboxylic acid and N-containing organic ligands as the bridge have been chosen to synthesize two-dimensional?2D?and three-dimensional?3D?MOFs.Second,based on MOFs structural characterization,its mechanism of action has been revealed in detail.The structure of MOFs is controlled by adjusting the kind of metal center and the length of organic ligand,i.e.structure transitions from two-dimensional structure to three-dimensional structure,and interpenetrating structure to single non-interpenetrating structure.Third,the relationship between structure and performance is demonstrated by the study of the properties of the MOFs.In this paper,the metal ions are used as the metal center of MOFs,and then the flexible polycarboxylic ligands with aromatic ring have been selected as bridged ligands,such as:4,4'-oxydibenzoic acid?H2oba?,4,4'-methylene bis?oxy?dibenzoic acid?H2mba?,4,4'-?propane-1,3-diylbis?oxy??dibenzoic acid?H2pba?,5,5'-?methylenebis?oxy??di isophthalic acid?H4mopa?,5,5'-?ethane-1,2-diylbis?oxy??diisophthalic acid?H4eopa?,5,5'-?butane-1,4-diyl?-bis?oxy?-diisophth alic acid?H4bopa?,5,5'-??oxy bis?ethane-2,1-diyl??bis?oxy??diisophthalic acid?H4oepa?,5,5'-??1,4-phenylenebis?methylene??bis?oxy??diisophthalic acid?H4popa?.In the end,auxiliary ligands containing nitrogen rings have been also employed as bridged linkages,such as:1,4-bis?1H-imidazol-1-yl?-butane?bib?and 1,4-bis??1H-imidazol-1-yl?methyl?benzene?bbtz?.35 coordination polymers have been synthesized successfully by using the selected active centers and organic ligands.The crystal structure,powder diffraction,UV-Vis spectra,IR spectra,thermogravimetric,fluorescence,magnetic and luminescent properties have been studied.The main contents in this paper is as follows:First,four MOFs were synthesized using H2oba,H2mba,H2pba and transition metal ions.They are[Zn2?oba?2?4,4?-bpy?]·H2O?1?,[Zn2?mba?2?4,4?-bpy?]·2H2O?2?,[Cd2?mba?2?4,4?-bpy?2]·4H2O?3?,[Zn2?pba?2?4,4?-bpy?]?4?.Structural analysis showed compound 1 with a double interpenetrating 3D network structure;a double parallel layer interpenetrating 2D network structure has been formed in compound 2and 4;compound 3 showed a 3D framework with 1D channels.The UV-vis diffuse reflectance spectrum analysis and fluorescence spectrum analysis revealed the compound 1-4 with the ligand internal charge transfer?ILCT?.The thermal stability analysis showed that the structural framework of the compound 1 was stable at 300°C,and compound 2-4 were stable under 400°C.Second,14 MOFs have been synthesized by using H4mopa,H4eopa,H4bopa,H4oepa,H4popa,bib,bbtz and transition metal ions Co2+and Zn2+.They are[Zn2?mopa??MeOH??COOH?]·DMF?5?,[Zn?mopa?0.5?4,4'-bpy??H2O?]·H2O?6?,[Zn4?mopa?2?bib?2?H2O?2]·4H2O?7?,[Zn?eopa??4,4'-bpy?]?8?,[Zn9?eopa?4?Imidazole??MeOH?2?H2O?8]·7H2O?9?,[Zn?bopa?0.5?4,4'-bpy?]·2H2O?10?,[M?bopa?0.5?bib?]·4H2O?M=Zn?11?,Co?12??,[Zn5?bopa?2.5?bbtz?5]?13?,[M2?oepa??bib?2]·3H2O?M=Co?14?,Zn?15??,[Zn3?oepa?1.5?bbtz?3]?16?,[Zn?popa?0.5?4,4'-bpy?]·2H2O?17?,[Zn?popa?0.5?bib?]·2H2O?18?.The compound 5,13 and 16 belong to 3D network skeleton structures.The compound 6,7 and 9 exhibit 2-fold interdigitated 2D?3D and 3D?3D network skeleton structures.A 3D structure was formed through two-dimensional multilayered interpenetrating in compound 8.The compound 10,11,12,14,15,17 and 18 are 3-fold interpenetrating 3D?3D network structures.The thermal stability analysis showed that the backbone of 14 compounds could be stablised below 400°C.The solid-state fluorescence analysis indicated 12compounds of Zn-MOF with strong emission bands,which indicated ILCT existed.Compound 10 and 17 demonstrated photochromic properties which be faded under heating conditions.Third,two MOFs,[Mn2?oba?2?CH3OH??H2O?]?19?and[Mn6?oba?6?bib??DMF?2?H2O?4]·?DMF?2?CH3OH??20?,were prepared with Manganese ion and H2oba,Manganese ion,bib and H2oba respectively.Structural analysis showed that the compound 19 is a 2D network structure with irregular channels.The compound 20is a 3D network structure with an irregular channel.The measurement of temperature dependence susceptibility for compound 19,20,Tetr-1,Hept-1 and Hept-2 were carried out,and the magnetization at 2K was measured the field dependence magnetization,and antiferromagnetic interactions between the manganese ions have been found in the five compounds.Fourth,two series of Ln-MOFs were synthesized by 4,4'-methylenebis?oxy?dibenzoic acid?H2mba?,4,4'-?propane-1,3-diylbis?oxy??dibenzoic acid?H2pba?and Ln3+.[Ln?mba?3?H2O?3]?Ln=La?21?,Nd?22?,Sm?23?,Eu?24?,Gd?25?,Tb?26?,Dy?27?,Ho?28?,Er?29?,Tm?30??and[Ln?pba?x?HCOO?x]?Ln=Sm?31?,Eu?32?,Gd?33?,Tb?34?,Dy?35??.Structural analysis showed that the compound 21-35 are 2D network skeletons with channels.The UV-vis and fluorescence spectra of 21-35showed that the strong absorption peak at 230-290 nm have been found in the compounds 21-35,which belong to the characteristic absorption bands of the ligands.The characteristic absorption and emission wavelength of the lanthanide ions have been found.In conclusion,we start from the point of view of MOFs crystal structure design.First,three series of novel 2D and 3D complexes have been synthesized by selecting transition/rare earth metal ions and flexible dicarboxylic acid ligands.The structure,luminescence and magnetic properties of the complexes are studied.Two,a series of novel 3D interpenetrating and non-interpenetrating complexes are synthesized by selecting transition metal ions and flexible four carboxylic acid ligands.The structure and luminescent properties were studied,and the structure activity relationship between photochromic and interpenetrating structures was found. |
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