| For the past decades, associated research on metal-organic frameworks (MOFs)has rapidly developed into one of the hot topics in chemistry and materials science.Comparing with traditional porous materials, as a novel functional material, MOFshave many advantages due to abundant topologies, structural tailorability andmodification, adjustable pore sizes, high surface area and so on. MOFs materials havecaptivated national researchers much attention due to their potential applications inthe fields of gas adsorption and separation, catalysis, magnetism, luminescence,sensors, etc. Design and synthesis of MOFs materials with novel structures anddesired functions are enormous challenges in this field.In this thesis, fifteen novel MOFs have been successfully synthesized by using2,2’-bipyridine-5,5’-dicarboxy (L1),(2,2’-bipy)2Ru(2,2’-bipyridine-5,5’-dicarboxy)(PF6)2(L2) and4-amino-3,5-bis(4-carboxyphenyl)-1,2,4-triazole (L3) as organicligands. Furthermore, the structures and properties such as gas sorption, magnetism,luminescence of these compounds were investigated.The main results in the thesis are summarized as follows:(1) Five three-dimensional (3D) MOFs and one2D layer coordination polymer,[Co3(L1)2(HCOO)2H2O]·2DMF (1),[Zn3(L1)2(HCOO)2]·H2O·DMF (2),[Mn(L1)]·DMA (3),[Co(L1)DMSO]·(DMSO)(H2O)(4),[Co(L1)H2O]·H2O (5) and[Cu(L1)]·DMSO (6), are solvothermally synthesized by using2,2’-bipyridyl-5,5’-dicarboxylic acid (L1) ligand with different transition metals.Compounds1and2display left-and right-handed helical chains, which are composedof vertex-sharing4-rings propagating along the c axial direction. Both of compounds manifest special stepwise N2and CO2adsorption behaviors with large hysteresisloops. The frameworks of1and2undergo structural transformation upon the removalof the guest molecules in the pores, which is indicated by the shift of powder X-raydiffraction peaks. These two flexible MOFs exhibit “opened” and “closed” behaviorsby the adsorption and removal of guest molecules. Furthermore, both of compoundsshow high selective CO2uptake over N2and CH4.In compound3, dinuclear Mn building units are linked by L1ligand to form a3D framework. The framework also exhibits two types of helical chains, which arecomposed of vertex-sharing4-rings propagating along the a axial direction. Incompound4, Co centers are interconnected by a bridging L1ligand to form1Dinfinite left/right helical chains of [Co-L1]nrunning along the [111] direction, andleft/right helical chains exist alternately. In compound5, the L1ligand is linked withthree Co centers to form a2D framework. The adjacent layers adopt an ABABstacking, which lead to the formation of rhombus channels. It is interesting to notethat the helical chains exist on the same layer and adjacent layers. Compounds4and5reveal two novel (3,3)-connected topologies. Compound6manifests left-andright-handed helical chains with4-connected dia topology. Additionally, the magneticproperties of compounds3-5are studied.(2) Five novel In-MOFs,[In(L1)(NO3)(DMA)0.5]·(DMA)(H2O)4.5(7),[In(L1)(HCOO)H2O]·(DMF)2(H2O)3(8),[In(L1)Cl]·(DMF)2(H2O)3(9),[In4(L1)5(HCOO)H2O]·(DMF)3(H2O)2(10) and [In(L2)H2O]·(DMF)2(11), have beensynthesized from2,2’-bipyridine-5,5’-dicarboxylic acid (L1) and(2,2’-bipy)2Ru(2,2’-bipyridine-5,5’-dicarboxy)(PF6)2(L2) ligand with indium ionsunder solvothermal conditions. Compounds7-9are constructed by the same ligand,but templated using three different anions (NO3, HCOO and Cl), and they exhibitthree different4-connected ung, crb and cbo network topologies. Compound7exhibits left-and right-handed single-helical chains alternate together. In the structureof compound8, there are two types of square metal–ligand channels with dimensionsof3.45×4.03and11.5×11.5, respectively. Compound9displays an interestingfeature of double-helical chains, each double-helical chain is made up of left-and right-handed helical chains. Furthermore, the role of anions in assisting the formationof distinct structures has been discussed. These three compounds display goodluminescence properties.In compound10, the trinuclear indium and monoatomic indium are linked withL1ligand to form2D layers, the adjacent layers are connected via the L1ligands withindium centers and generate a3D pillar-layer framework. Compound10exhibits ahigh selectively sensing ability of Fe3+based on the free pyridyl nitrogen atoms in thestructure, which exhibits potential applications for recognizing and sensing functionsto metal ions. Additionally, the N2, CO2, H2, CH4, C2H6and C3H8gas adsorption ofthis compound have been explored. The CO2/CH4, C2H6/CH4, C3H8/CH4adsorptionselectivity by IAST calculating are4.9,15.4and168.3, respectively. In structure ofcompound11, the trinuclear inorganic building units are connected with L2ligand toform a3D MOF with acs topology. Compound11reveals good luminescenceproperty.(3) One novel3D MOF with (3,4)-connected topology,[Cu3I2(L3)H2O]·(DMF)2(H2O)(12), has been synthesized by using4-amino-3,5-bis(4-carboxyphenyl)-1,2,4-triazole (L3) ligand and CuI. In compound12, dinuclear [Cu2(CO2)4] and Cu4I4inorganic building units are linked by L3ligandto generate left-and right-handed helical chains along the c axis with a pitch of23.2. In the study of single-crystal to single-crystal (SCSC) structural transformations,the crystals of compound12are solvent exchanged with dry ethanol, ethanol replacesthe guest molecules in the pores of crystals. After which the desolvated crystals ofcompound,[Cu3I2(L3)H2O](13), are obtained. Then, the crystals of compound13were soaked in dry ethanol solution of I2and cyclohexane solution of I2for one week,respectively, after which crystals of compound,[Cu3I2(L3)H2O]·(C2H6O)(0.5I2)(14),[Cu3I2(L3)H2O]·(C6H12)(0.5I2)(15), are obtained. Structural analyses show thatcompounds13and14have same frameworks, the only difference are the guestmolecules in the channels, which show SCSC transformations phenomenon uponexchange of the solvent of compound12in the pores. In the structure of compound15,Cu4I4clusters occur cleavage and regeneration of coordination bonds to generate CunInchains. Compound13displays interesting ability of the uptake and release ofiodine.In this thesis, we successfully synthesized15novel MOFs by the rationalselection of the organic linkers and metal ions. Furthermore, the characterization ofcompounds and their corresponding properties have been explored. Some compoundsshow unique gas adsorption properties, as well as good magnetic and fluorescentproperties. |
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