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New Linkers for Organic-Inorganic Hybrid Materials

  • In this study, two outstanding subgroups of organic-inorganic hybrid materials have been investigated. The first part covers the design, synthesis, characterization and application of seven novel Metal Organic Frameworks (MOFs) containing functionalized biphenyl dicarboxylates as linkers. In the second part, the surface modification of the metal oxides ZrO2, TiO2 and Al2O3 using phosphonate derivates is reported. Firstly three functionalized MOF structures; ZnBrBPDC, ZnNO2BPDC and ZnNH2BPDC were synthesised using 4,4´-biphenyldicarboxylic acid derivatives with different functional groups (-Br, -NO2, -NH2) Powder X-ray diffraction (PXRD) measurements indicated that the synthesised MOFs posses the interpenetrated IRMOF-9 structure with a cubic topology, which was also confirmed with single crystal X-ray measurements. The chemical structure of the MOF materials was further proved by solid state NMR and IR measurements. N2 adsorption measurements showed Type I isotherms for all three structures with large surface areas. TGA measurements of the evacuated samples were in good agreement with the elemental analysis data. The results proved that their thermal stability is between 325 °C - 450 °C. Adsorption properties of these MOF structures were tested using light alkanes (CH4, C2H6, C3H8, and n-C4H10) at three different temperatures. For all adsorbents, the maximum uptakes were observed at 273 K. When the temperature was increased, the amount of the adsorbed gas decreased. All three MOFs showed strong affinities for n-butane. The lowest uptakes were observed for CH4. The effect of functional groups on the IRMOF series was also examined by synthesizing amide functionalized biphenyl linkers. For this purpose, four different linkers containing amides with different alkyl chains (C1-C4) were synthesized and used for the synthesis of four new MOF structures ZnAcBPDC, ZnPrBPDC, ZnBuBPDC and ZnPeBPDC. PXRD measurements of ZnAcBPDC indicated that the structure contains two different phases. PXRD patterns of ZnPrBPDC, ZnBuBPDC and ZnPeBPDC revealed non-interpenetrated structures which were further proved by single crystal X-ray measurements. The chemical structure of the MOF materials was further confirmed by X-ray spectoscopy, solid state NMR and IR measurements. N2 adsorption measurements of the MOF structures were carried out using different activation methods. For all four MOFs, Type I isotherms were obtained. ZnAcBPDC showed the highest BET surface area. ZnAcBPDC and ZnBuBPDC were tested for their alkane, alkene and CO2 adsorption capacities. In the second part of the work, the surface modification of three different metal oxides, ZrO2, TiO2 and Al2O3 was performed. For this purpose firstly three different fluorescent phosphonate derivatives containing thiophene units were synthesized from their halo derivatives in a four step synthesis and then used as coupling molecules for the surface modification. Nine different surfaces were obtained (38@TiO2, 39@TiO2, 40@TiO2, 38@Al2O3, 39@Al2O3, 40@Al2O3, 38@ZrO2, 39@ZrO2, 40@ZrO2). All three modified metal oxide surfaces were characterized using elemental analysis, solid state NMR and IR spectroscopy. The BET surface areas of the materials were determined by N2 adsorption measurements. TGA was used to determine the stability of the surfaces. Maximum loadings were obtained for ZrO2 surfaces. Due to the strong luminescence of the coupling molecules, the modified surfaces were checked for their light emission. All ZrO2 and Al2O3 surfaces showed fluorescence with exception of 40@Al2O3. On the other hand, for the modified TiO2 surfaces, no fluorescence could be observed.

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Author:Ezgi Keceli
URN (permanent link):urn:nbn:de:hbz:386-kluedo-33852
Advisor:Werner R. Thiel
Document Type:Doctoral Thesis
Language of publication:English
Publication Date:2013/01/15
Year of Publication:2012
Publishing Institute:Technische Universität Kaiserslautern
Granting Institute:Technische Universität Kaiserslautern
Acceptance Date of the Thesis:2012/09/20
Date of the Publication (Server):2013/01/15
Number of page:XI, 207
Faculties / Organisational entities:Fachbereich Chemie
DDC-Cassification:5 Naturwissenschaften und Mathematik / 540 Chemie
Licence (German):Standard gemäß KLUEDO-Leitlinien vom 10.09.2012