Guest inclusion in porous metal-organic crystals and high-pressure single-crystal X-ray diffraction analysis at low temperatures

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dc.contributor.advisorBarbour, Leonard Jamesen_ZA
dc.contributor.authorKutama, Aluwanien_ZA
dc.contributor.otherStellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science.en_ZA
dc.date.accessioned2024-03-04T14:44:26Zen_ZA
dc.date.accessioned2024-04-26T19:43:39Zen_ZA
dc.date.available2024-03-04T14:44:26Zen_ZA
dc.date.available2024-04-26T19:43:39Zen_ZA
dc.date.issued2024-03en_ZA
dc.descriptionThesis (MSc)--Stellenbosch University, 2024.en_ZA
dc.description.abstractENGLISH ABSTRACT: Porous metal-organic materials are an intriguing class of compounds that are capable of adsorbing guest molecules, such as gases, into their cavities. This ability of these materials has stimulated research across various domains, including purification, gas storage, separation, and drug delivery. In this study, we analyzed two well-known porous metal-organic compounds namely, [Zn2(L1)(OBA)2] and [Cu2(L2)2(Cl)4]. The metal-organic framework (MOF), [Zn2(L1)(OBA)2], was successfully synthesized and fully characterized in preparation for gas sorption studies. This characterization included single crystal Xray diffraction (SCXRD), thermogravimetric analysis (TGA), and Fourier-transform infrared (FT-IR) spectroscopy. Gas sorption studies were thereafter carried out using volumetric sorption analysis and pressure-ramped differential scanning calorimetry (P-DSC) up to 50 bar using CO2 and C2H4. The sorption profiles with CO2 indicated the presence of shape memory, while the sorption profiles with C2H4 were indicative of Type 1 isotherms. In addition, the metallocycle [Cu2(L2)2(Cl)4], was synthesized using a layering methodology that required the use of three solvents (namely EtOAc, DMF and EtOH), and further studies revealed that EtOAc was the solvent that was included in the crystal structure and hence responsible for the structural channel formation. The characterization of [Cu2(L2)2(Cl)4] involved using powder X-ray diffraction, SCXRD, TGA, FT-IR, and thereafter the activated crystals were pressurized up to 20 bar with CO2 and characterized using, gravimetric sorption analysis and P-DSC. In this work a novel method for obtaining high-pressure SCXRD data at low temperatures is also described for the first time and utilized primarily to reduce the thermal motion of the included guest molecules for structural modelling purposes. This was carried out with CO2 (20 bar) and Xe (10 bar). The results revealed acceptable molecular geometrical parameters for the included CO2 guest molecule, and that the cavity of [Cu2(L2)2(Cl)4] increased in volume to accommodate the large Xe molecule, indicating the flexible nature of this metallocycle.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Poreuse metaal-organiese materiale is 'n belangwekkende klas verbindings wat in staat is om gasmolekules, soos gasse, in hul holtes te adsorbeer. Hierdie vermoë van hierdie materiale het navorsing oor verskeie domeine gestimuleer, insluitend suiwering, gasberging, skeiding en geneesmiddelaflewering. In hierdie studie het ons twee bekende poreuse metaal-organiese verbindings ontleed, naamlik [Zn2(L1)(OBA)2] en [Cu2(L2)2(Cl)4]. Die metaal-organiese raamwerk (MOF), [Zn2(L1)(OBA)2], is suksesvol gesintetiseer en volledig gekarakteriseer ter voorbereiding vir gassorpsiestudies. Hierdie karakterisering het enkelkristal Xstraaldiffraksie (SCXRD), termogravimetriese analise (TGA) en Fourier-transformasie infrarooi (FTIR) spektroskopie ingesluit. Gassorpsiestudies is daarna uitgevoer deur gebruik te maak van volumetriese sorpsie-analise en drukverhoogde differensiële skanderingkalorimetrie (P-DSC) tot 50 bar met CO2 en C2H4. Die sorpsieprofiele met CO2 het die teenwoordigheid van vormgeheue aangedui, terwyl die sorpsieprofiele met C2H4 'n aanduiding was van Tipe 1 isoterme. Daarbenewens is die metallosiklus [Cu2(L2)2(Cl)4], gesintetiseer deur gebruik te maak van 'n gelaagde metodologie wat die gebruik van drie oplosmiddels (naamlik EtOAc, DMF en EtOH) vereis het, en verdere studies het aan die lig gebring dat EtOAc die oplosmiddel was wat ingesluit in die kristalstruktuur en dus verantwoordelik vir die strukturele kanaalvorming. Die karakterisering van [Cu2(L2)2(Cl)4] behels die gebruik van poeier X-straaldiffraksie, SCXRD, TGA, FT-IR, en daarna is die geaktiveerde kristalle tot 20 bar onder druk geplaas met CO2 en gekarakteriseer deur gebruik te maak van gravimetriese sorpsie-analise en P-DSC. In hierdie werk word 'n nuwe metode vir die verkryging van hoëdruk SCXRD-data by lae temperature ook vir die eerste keer beskryf, en hoofsaaklik gebruik om die termiese beweging van die ingeslote gasmolekules vir strukturele modelleringsdoeleindes te verminder. Dit is uitgevoer met CO2 (20 bar) en Xe (10 bar). Die resultate het aanvaarbare molekulêre geometriese parameters vir die ingeslote CO2-gasmolekule geopenbaar, en dat die holte van [Cu2(L2)2(Cl)4] in volume toegeneem het om die groot Xe-molekule te akkommodeer, wat die buigsame aard van hierdie metallosiklus aandui.af_ZA
dc.description.versionMastersen_ZA
dc.format.extentviii, 81 pages : illustrationsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/130496en_ZA
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshMetal-organic frameworksen_ZA
dc.subject.lcshPorous materials en_ZA
dc.subject.lcshGas sorptionen_ZA
dc.subject.lcshVolumetric analysisen_ZA
dc.subject.lcshCrystallizationen_ZA
dc.titleGuest inclusion in porous metal-organic crystals and high-pressure single-crystal X-ray diffraction analysis at low temperaturesen_ZA
dc.typeThesisen_ZA
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Masters Degrees (Chemistry and Polymer Science)