Synthesis,Structures And Properties Of Novel Metal-Organic Frameworks Based On Silicon-Centered Tetrahedral Ligand

Metal-organic frameworks （MOFs） represent a new class of hybridorganic-inorganic supramolecular materials comprised of ordered networks formedfrom organic electron donor linkers and metal cations. Since their discovery, MOFshave received extensive exploration, with applications ranging from gas storage tocatalysis to optics, and to magnetics. In light of the importance of the attractivefeatures of MOFs, there have been tremendous research efforts devoted to thedevelopment of such materials. In this account, to design always newer and newerstructures, more and more novel polycarboxylic acids have been employed in theconstruction of such materials, especially some three-dimensional tetrahedral ligandshave been adopted, instead of the most common benzene–polycarboxylate ligands,which are bent, or liner, or planar. However, there is an unfavorable lack ofinvestigation on characterization of the compounds of such three-dimensionaltetrahedral ligands. In this work, our group chose H₄TCPS as a three-dimensionaltetrahedral Silicon-centered ligand to construct MOFs. By changing the metal center,the synthesis conditions, and combination of various aromatic N-donor auxiliaryligands, we successfully obtained a series of4-connected3D coordination networksby ligand-directed. And the structure of these compounds are analyzed, meanwhile,the thermal stability, magnetic properties, and luminescent properties have been investigated. In this thesis, the research work can be divided into the followingaspects:1. Seven3D transition metal–organic frameworks （MOFs） constructed fromfour different inorganic secondary building units, have been synthesized byself-assembly of the rigid silicon-centered tetrahedral carboxylate ligand H4TCPS andcadmium（II）、zinc（II）、manganese（II）、copper（II）、cobalt（II） ions under solvothermalreactions. Cd₂（TCPS）（H₂O）₂·G（1）、 Zn₂（TCPS）（H₂O）₂·G（2）、Mn₂（TCPS）（H₂O）₂·G（3）were built from a one-dimensional chain secondary structuralunit and TCPS unit, having excellent fluorescence properties. Zn₃（HTCPS）₂·G （4） wasa （4,8）–connected3D framework constructed by trinuclear metal zinc ion clustersand TCPS unit, Schl fli symbol is（4⁴6²）₂(4⁸·6¹⁷8³).Zn₄（TCPS）₂（H₂O）₅·G（5）exhibited a （4,4）-connected2-fold interpenetratingthree-dimensional framework with SrAl₂topology, constructed of the4-connectedtetrahedral TCPS unit with the4-connected different dinuclear zinc ion secondaryunits, its Schl fli symbol is （4²?6³?8）. Cu₂（TCPS）（H₂O）₂·G （6） was a （4,4）–connected3D framework constructed by binuclear copper ion paddle-wheel SBU andTCPS unit, Schl fli symbol is（4²?8⁴）. Co₃（HTCPS）₂·G （7） exhibited a （4,8）-connected three-dimensional framework with a distorted version of the CaF2typetopology, constructed of the4-connected tetrahedral TCPS unit with the4-connectedtrinuclear zinc ion secondary units, its Schl fli symbol is （4⁶）2(4¹²?6¹⁰?8⁶).2. Two2-fold different interpenetrating metal–organic frameworks （MOFs） havebeen synthesized by self-assembly of the rigid silicon-centered tetrahedral carboxylateligand H4TCPS and Zn（II） ions with the combination of aromatic N-donor auxiliaryligands（IM and BIPY） under similar synthesis conditions. From the topological pointof view, Zn₄（TCPS）₂（IM）（DMA）·G（8） exhibits a （4,4）-connected2-foldinterpenetrating3D diamond type of network, its Schl fli symbol is （66）;Zn₂（TCPS）（BIPY）·G （9） exhibits a type of （4,6）-connected2-fold interpenetrating3D sqc422network, its Schl fli symbol is(4²·5¹⁰·7²·8)（4²·5⁴）. The fluorescenceproperties of the compounds is characterized.3. Two3D multifunctional lanthanide metal–organic frameworks （MOFs）, Pr（HTCPS）（H₂O）·2DMF·C₂H₅OH·5H₂O（10） andPr₃（TCPS）₂（NO₃）（H₂O）₄（DMA）₂·2DMA·C₂H₅OH·3H₂O （11） have been synthesizedby self-assembly of the rigid silicon-centered tetrahedral carboxylate ligand H₄TCPSand Pr（III） ions under different solvothermal reactions. X-ray crystallographyrevealed that they exhibited a rare （4,8）-connected CaF2topology framework,constructed of the4-connected tetrahedral TCPS unit with the8-connected dinuclearpraseodymium cluster unit and trinuclear praseodymium cluster unit, respectively, theSchl?i symbol is (4¹²·6¹²·8⁴)（4⁶）₂. In addition, the luminescent and magneticproperties of two compounds are investigated. The differences in the optical andmagnetic properties could be ascribed to the different structures, which mainly basedon different praseodymium clusters.4. Two3D multifunctional lanthanide metal–organic frameworks （MOF）,Er₄（TCPS）₃（H₂O）₆·10DMF·4H₂O （12） and Er（HTCPS）（H₂O）·G （13） have beensynthesized by self-assembly of Er（III） ions and rigid silicon-centered tetrahedralcarboxylate ligands under solvothermal reactions. X-ray crystallography reveals thatcompound12exhibits a unique trinodal （4,12）-connected topology, constructed fromtetranuclear erbium clusters as12-connected nodes and tetrahedral ligands TCPS as4-connected nodes. To the best of our knowledge, compound12is the first example oflanthanide MOFs with trinodal （4,12）-connected topology structure, the Schl aflisymbol is (4³⁰.6²⁶.8¹⁰)（4⁶）₃. It should be noted that, this unusual framework representsan unlisted net in the classification of EPINET, RCSR, and TTD. More interesting,compound12undergoed an unprecedented single-crystal-to-single-crystaltransformation at room temperature. Compound13, which exhibited a rare （4,8）-connected CaF₂topology framework, constructed of the4-connected tetrahedralTCPS unit with the8-connected dinuclear erbium cluster unit, was formed byleaving compound12in the original solution and kept at room temperature for twoweeks. In addition, the luminescent and magnetic property of the compounds isinvestigated.5. Six multifunctional lanthanide metal–organic frameworks （MOFs）,M（HTCPS）（H₂O）_1.5[M=Tb （14）, Er （15）, Dy （16）, Tm （17）, Y （18） and Pr （19）], have been synthesized by the reaction of the lanthanide metal ion （Ln3?） with the rigidSilicon-centered tetrahedral carboxylate ligand H4TCPS by hydrothermal synthesismethod. X-ray diffraction analyses reveal that they are extremely similar in structureand crystallized in monoclinic space group C2/c. Two eight-coordinated metal centersand four tetrahedral TCPS groups construct a paddle-wheel building block. Thepaddle-wheel building blocks assemble with each other through one oxygen bridgefrom a water molecule to lead to a one-dimensional （1D） infinite inorganic rod-shapedchain,–Ln–O–C–O–Ln–, along the [001] direction. These1D inorganic rod-shapedchains are linked with phenyl groups of the tetrahedral TCPS ligand to form a3Dframework. In addition, the luminescent and magnetic properties of these compoundsshow that they could be anticipated to be potential antiferromagnetic and fluorescentmaterials.