Metal Organic Frameworks:Synthesis, Structure And Property

A series of Metal-Organic frameworks (MOFs) were synthesized and structurally characterized. Accordingly, their potential properties such as photoluminescence, metal ion-exchange, catalysis and gas separation were investigated. In this thesis, six chapters are included. Chapter1mainly reviews background knowledge about Metal-Organic Frameworks including the definition, structure characteristics, topology, as well as recently research advance in some applications such as photoluminescence, ion-exchange, catalysis and gas separation. Chapters2-6mainly describe my research work in this area.In chapter2, a series of Zn2+based Metal Organic Frameworks (MOFs): Zn(DBTA)(imid)2, Zn(DBTA)(2,2’-bpy), Zn2(DBTA)2(Py),[Zn(DBTA)(DPP)]-DMF, Zn(DBTA)(DPEA), Zn2(DBTA)2(4,4’-bpy),[Zn(DBTA)(3,4’-DPEE)]-DMF and Zn3(DBTA)3(3,4’-DPEE)2DMF were rationally designed and synthesized using a conjugated thiophene derived aromatic carboxylic acid (H2DBTA) under the regulation of different N-donor co-ligands such as imid (imidazole),2,2’-bpy (2,2’-bipyridine), Py (pyridine), DPP (1,3-di(pyridin-4-yl)propane), DPEA (1,2-di(pyridin-4-yl)ethane) and3,4’-DPEE ((E)-3,4’-(ethene-1,2-diyl)dipyridine). The N-donor co-ligands play a crucial role in crystal fabrication of the eight compounds by directing the coordination modes of Zn2+and the H2DBTA ligands. The photoluminescent properties of these compounds, including excitation, emission and radiactive lifetime, have also been investigated in order to tentatively explore their structure-property relationships.In chapter3, four new metal-organic frameworks (MOFs):[Cd(DBTDC-O2)(Py)2]n, Zn2(DBTDC-O2)2(4,4’-bipy)]n,[Zn(DBTDC-O2)(DIB)]n and [Co(DBTDC-O2)(2,2’-bipy)]n (H2DBTDC-O2=Dibenzothiophene-5,5’-dioxide-3,7-dicarboxylic acid, Py=pyridine,4,4’-bipy=4,4’-bipyridine,2,2’-bipy=2,2’-bipyridine, DIB=1,4-di(1H-imidazol-1-yl)butane) were constructed from H2DBTDC-O2, different metal ions in the presence of various N-donor co-ligands, under solvothermal conditions. Solid-state properties for these crystalline materials, such as thermal stability, luminescent emission and the radiative lifetime of their emissions have been investigated. In particular,[Zn2(DBTDC-O2)2(4,4’-bipy)]n and [Zn(DBTDC-O2)(DIB)]npresent guest-responsive luminescent properties.In chapter4, four new metal organic frameworks based on flexible V-type tetracaboxylate ligands [Me2NH][In(mdip)]?2.5DMF?4H2O,[Zn2(mdip)(bpe)2]-3H2O,[Co2(mdip)(4,4’-bipy)2]?2.5DMF?7H2Oand [Co4(mdip)2(μ2-O)2(py)7]’3DMF?7.5H2O (H4mdip=5,5’-methylenediisophthalic acid,4,4’-bipy=4,4’-bipyridine, bpe (E)-1,2-di(pyridin-4-yl)ethene, py=pyridine), were synthesized using solvothermal reactions.[Me2NH][In(mdip)]?2.5DMF?4H2Ois a3D anionic framework with a (42?63?8) Schlafli symbol and exhibits selective ion exchange (M=Li+, Na+, K+, Mg2+Ca2+, Sr2+, Ba2+, Cu2+, Fe3+). What is more, it has a suitable Lewis acidity and good chemical stability, which makes it a good heterogeneous catalyst for the Friedel-Crafts alkylation of pyrrole with nitroolefins.[Zn2(mdip)(bpe)2]?has a3D framework with a novel (62?84)(64?82)2Schlafli symbol, which is first found for4-connected binodal network.[Co2(mdip)(4,4’-bipy)2]?2.5DMF?7H2Ois a3D open porous framework and exhibits a (4,6)-connected binodal network with a (44?610?8)(44?62) Schlafli symbol.[Co4(mdip)2(μ2-O)2(py)7]?3DMF?7.5H2O crystallizes in a chiral space group P32and has a3D4-connected uninodal network with a Schlafli symbol of (65?8). It possesses regular triangular (ID) homochiral channels with an edge of14.7A along the c axis. The crystal structures and coordination modes of H4midp, as well as regulatory effect of N-donor co-ligands in these compounds were discussed.In chapter5, a new three-dimensional microporous metal-organic framework [Cu(N-(pyridin-4-yl)isonicotinamide)2(SiF6)](EtOH)2(H2O)12(UTSA-48, UTSA=University of Texas at San Antonio) with functional-CONH-groups on the pore surfaces was synthesized and structurally characterized. The small pores and the functional-CONH-groups on the pore surfaces within the activated UTSA-48a have enabled their strong interactions with C2H2and CO2of adsorption enthalpy of34.4and30.0KJmol-1, respectively. Accordingly, activated UTSA-48exhibits highly selective gas sorption of C2H2and CO2over CH4with the Henry Law’s selectivities of53.4and13.2respectively, at296K, thereby, highlighting the promise for its application in industrially important gas separation.In chapter6, a Zeolite-like Zinc-Tetrazole Framework based metal organic framework [Zn(mtz)2](UTSA-49) with open donor N atoms on the pore surfaces was synthesized and structurally characterized. The small pores, open donor N atoms and π-electron system of aromatic tetrazole rings on the pore surface have enable strong interactions with CO2of adsorption enthalpy of33KJmol"1. Accordingly, activated UTSA-49shows highly selective gas sorption of CO2over CH4with the Henry Law’s selectivities of25.5at296K and43.3at273K, thereby highlighting the promise for its application in industrially important gas separation.