The Functionalization, Size Control And Properties Of Metal-Organic Framework Materials

Recent years, Metal-Organic Framework (MOF) materials have drawn great attentions due to their potential applications in gas sorption/separation and luminescent sensing. In this dissertation, the recent progress of MOF materials is reviewed, with specific focus on the functionalization, size control and properties of MOF materials. A cationic MOF material was synthesized, and small hydrocarbons C1/C2sorption/separation properties were studied. A MOF with both open metal sites and Lewis basic pyridyl sites was developed, and C2H2, CO2and CH4gas sorption/separation properties were explored. A nanoscale MOF material with controllable size was realized whose morphology has been simulated base on the BFDH method, and the sensing of bacteria endospores was research in detail. We also report the synthesis and sensing of nitroaromatic explosives of a nanoscale MOF material.A new cationic MOF material ZJU-48(ZngO (EDDA)4(ad)4·(HEDDA)2·6DMF·27H2O; H2EDDA=(E)-4,4’-(ethene-1,2-diyl) dibenzoic acid; ad=adenine) was solvothermally synthesized and the gas sorption/separation properties for small hydrocarbons was studied. ZJU-48features a three-dimensional structure with cationic skeleton and has one-dimensional pores of about9.1×9.1A2. The N2sorption isotherm at77K showed that ZJU-48a displayed Type-I sorption behavior with a BET surface area of1450m2g-1. ZJU-48a takes up C2H2(57cm3g-1), and this value is higher than the one with similar Zn4O structure MOF-5(26cm3g-1), which revealed that the structrue feature of charged skeleton in ZJU-48a played an important role in its acetylene storage. The enthalpy of C2H6is28.0KJmol-1, which is very high and is even comparable to that of Mg-MOF-74. This indicated that the charged skeleton in ZJU-48a do enhance the affinity between MOF and small hydrocarbon molecules, presumably by charge-induced forces between the charged skeleton and polarized gas molecules. Moreover, the adsorption selectivities of C2H6with respect to CH4are in excess of6.0for a range of pressure to100KPa, indicating the feasibility of this MOF for the practical application on C2/C1separation. To further demonstrate the feasibility for the practical separation, the breakthrough and pulse chromatographic experiments were simulated and the result showed that ZJU-48a has the ability of separating CH4in pure form from this quaternary mixture. The results indicated that the charged skeleton strategy can enhance the affinity between MOF material and polarized C2gas molecules, this strategy provided a new design approach for MOF materials.To immobilize both open metal sites and Lewis basic pyridyl sites into a microporous MOF material, UTSA-50(Cu6(PDC)6-2.6H2O; PDC=3,5-pyridine-dicarboxylate) was solvothermally synthesized and the C2H2, CO2and CH4gas sorption/separation properties were explored. UTSA-50features a three-dimensional structure with both open metal sites and Lewis pyridyl sites. The pore size is6-11A. The N2sorption isotherm at77K showed that UTSA-50a displayed Type-I sorption behavior with a BET surface area of604m2g"’. The amount of C2H2absorbed in UTSA-50(90.6cm3g-1) is higher than the ones without functionalization sites such as MOF-5, ZIF and cationic MOF ZJU-48. The storage density of adsorbed acetylene in UTSA-50a micropores is0.30g cm-3, which is among the high end for MOF materials. The enthalpy for acetylene reached a high value of39.4KJmol-1, which indicated that the high density of open metal sites and Lewis basic pyridyl sites do enhance the affinity between the MOF surface and acetylene molecules, presumably by Coulomb interactions and hydrogen bonding. The most remarkable feature of UTSA-50a is the significant high C2H2/CH4selectivity of68.0, which is the highest one ever reported. The results illustrated the power of collaborative immobilization of multiple functional sites and further realize both high acetylene capacity and selectivity. This research initiated an important design approach for highly effective gas sorption/separation MOF materials.A nanoscale MOF material EuFO (Eu2(FMA)2(OX)(H2O)4-4H2O; FMA=fumarate, OX=oxalate) with controllable size and morphology is realized whose morphology has been simulated based on the BFDH method, and the sensing properties of bacteria spores was researched in detail. The sizes and morphologies can be tuned by the molar ratio of surfactant and H2O molar ratio (W value), which resulted the EuFO evolution from large to micro crystals, and finally became nano crystals. Hexagonal nanoplates with size of100nm can be synthesized at W=15. The BFDH method calculation showed that there were three possible growing facets for EuFO crystals, they are{022},{004} and {111}, and the addition of surfactant makes different facets growth rates, which finally leads to different sizes and morphologies of EuFO crystals. The hexagonal nanoplates showed highly sensitive and selective sensing of bacteria spore. Luminescent lifetime showed that the DPA molecules are involved in the binding with Eu(III) which can significantly enforce the intramolecule energy transfer. It is foreseen that functional nanoscale MOF will establish the foundation for in vivo biosensors.A nanoscale MOF EuBDC (Eu2(BDC)3(H2O)2·(H2O)2; BDC=benzene-1,4-dicarboxylate) has been realized for sensing of nitroaromatic explosives. EuBDC nanorods with size of100nm can be synthesize by microemulsion method at W=15. The nanoscale EuBDC showed both highly sensitive and selective sensing of nitroaromatic explosives. Luminescent lifetime and UV-Vis showed that luminescence change of the nanoscale EuBDC was attributed to a competition of absorption of the light source energy, which decreased the probability of energy transferr from ligand to Eu(Ⅲ) and subsequently quenched the luminescence of Eu(Ⅲ). The results showed that size control of MOF materials is an important strategy to realize straightforward and high sensitive environmental and biological sensing.