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Characterisation and sorption study of a highly symmetrical porous metal-organic framework
Thesis (MSc)--Stellenbosch University, 2020.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2020
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| _version_ | 1867613768139145216 |
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| access_status_str | Open Access |
| author | Wei, Xueting |
| author2 | Barbour, Leonard J. |
| author_browse | Barbour, Leonard J. Wei, Xueting |
| author_facet | Barbour, Leonard J. Wei, Xueting |
| author_sort | Wei, Xueting |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2020. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/108361 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:41:23.238Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/108361 Characterisation and sorption study of a highly symmetrical porous metal-organic framework Wei, Xueting Barbour, Leonard J. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Crystallography Metal-organic frameworks Porous materials UCTD Thesis (MSc)--Stellenbosch University, 2020. ENGLISH ABSTRACT: Supramolecular chemistry is a young yet rapidly growing interdisciplinary field. A class of compounds called metal-organic frameworks (MOFs) has attracted increasing attention over the last two decades. One of the reasons for this is their porous and dynamic nature, which make them attractive candidates for various applications. In this study the MOF CdK34pba, is investigated. In particular, we focused on the characterisation of CdK34pba and explored its sorption properties. The first section discusses the characterisation of CdK34pba. The as-synthesised framework forms large 1D channels along the crystallographic c axis, with offset face-to-face (OFF) π‒π interactions between two nearby ligands, thus stabilising the structure. The 1D channels comprise approximately 43% of the unit-cell volume. The porous nature is maintained by potassium ions binding the channel walls together, thus preventing interpenetration. The channels in the as-synthesised CdK34pba contain water and DMF, which can be successfully removed without any structural changes. The material absorbs moisture from the ambient environment. CdK34pba undergoes two thermal events, one during heating and one during cooling. The thermal event during heating could be caused by a sudden decrease in volume. The second thermal event during cooling could be due to the change in gradient at which the volume decreases. However, further investigation is required to definitively explain these events. The second section investigates the sorption properties of CdK34pba. Guest exchange experiments, using the as-synthesised CdK34pba, with a variety of organic solvents indicate that CdK34pba does not undergo structural changes with selected solvent exchanges. The guest occupancy is dependent on the physicochemical identity of the solvent molecule, which suggests the potential for solvent separation. Gas sorption experiments revealed the uptake capacity for CO2, N2, methane, ethylene, propane, and butane. The isotherms suggest that at 20 bar CdK34pba has not reached its maximum capacity for selected gases. Further higher pressure gas sorption experiments could be carried out to establish the maximum gas loading capacity. The capability of CdK34pba to sorb xylene isomers was explored using xylene solvents and vapours. The xylene solvent sorption experiments showed that the uptake is the highest for m-xylene. The m-xylene guest was successfully modelled; it is hydrogen bonded to the nitrate counter ion as well as a water molecule, possibly absorbed from the environment. Lastly, a proof of concept dye sorption experiment was performed. CdK34pba can extract 10 ppm of sunset yellow dye from EtOH solvent under 24 hours at 40 °C. The structure and thermal properties of CdK34pba were explored. Sorption and exchange experiments established the uptake capacity of CdK34pba for various guests. Further investigations should be performed to explain any unanswered questions. AFRIKAANSE OPSOMMING: Supramolekulêrechemie is 'n jong, maar vinnig groeiende interdissiplinêre veld. 'n Klas verbindings genaamd metaalorganiese raamwerke (MOFs) het die afgelope twee dekades toenemende aandag getrek. Een van die redes hiervoor is hul poreuse en dinamiese aard, wat hulle aantreklikke kandidate vir verskillende toepassings maak. In hierdie studie word die MOF CdK34pba ondersoek. Ons het veral gefokus op die karakterisering van CdK34pba en het die sorpsie-eienskappe daarvan ondersoek. In die eerste afdeling word die karakterisering van CdK34pba bespreek. Die soos-gesintetiseerde raamwerk vorm groot 1D kanale in die rigting van die kristallografiese c as, met geskuifde gesig-tot-gesig (OFF) π-π interaksies tussen twee nabygeleë ligande. Dus stabiliseer hierdie interaksies die struktuur. Die 1D kanale beslaan ongeveer 43% van die eenheidsel-volume op. Die poreuse aard word gehandhaaf deur die kalium ione wat bind aan die kanaalmure en keer dus enige interpenetrasie. Die kanale in die soos-gesintetiseerde CdK34pba bevat water en DMF, wat suksesvol verwyder kan word sonder enige strukturele veranderinge. Die materiaal absorbeer vog vanuit die omringende omgewing. CdK34pba ondergaan twee termiese gebeurtenisse, een tydens verhitting en een tydens verkoeling. Die termiese verandering tydens verhitting is moontlik die oorsaak van 'n skielike afname in eenheidsel-volume. Die tweede termiese gebeurtenis tydens verkoeling is moontlik as gevolg van ‘n verandering in die gradiënt waarmee die volume afneem. Verdere ondersoek is egter nodig om hierdie gebeure daadwerklik te verklaar. Die tweede afdeling ondersoek die sorpsie-eienskappe van CdK34pba. Oplosmiddel uitruiling eksperimente van die soos-gesintetiseerde CdK34pba met 'n verskeidenheid van organiese oplosmiddels dui daarop dat CdK34pba nie strukturele veranderinge met die gekose oplosmiddel ondergaan nie. Die besetting van die oplosmiddel is afhanklik van die fisiko-chemiese identiteit van die oplosmiddel molekule, wat potensiaal aandui vir oplosmiddel skeiding. Gassorpsie-eksperimente het die opneemkapasiteit vir CO2, N2, metaan, etileen, propaan en butaan getoon. Die isoterme dui daarop dat het CdK34pba nie die maksimum kapasiteit vir die geselekteerde gasse by 20 bar bereik het nie. Verdere gassorpsie-eksperimente onder 'n hoër druk kan uitgevoer word om die maksimum kapasiteit vir die gas te bepaal. Die vermoë van CdK34pba om xileen-isomere op te neem is ondersoek deur gebruik te maak van xileen vloeistowwe en dampe. Die xileen oplosmiddel sorpsie eksperimente het getoon dat die opname die hoogste is vir m-xileen. Die m-xileen gas is suksesvol gemodelleer; dit is deur ʼn waterstofbinding met die nitraat-teenioon, sowel as 'n watermolekule, wat moontlik uit die omgewing opgeneem word, gebind. Laastens is 'n bewys-van-konsep kleurstofsorpsie-eksperiment uitgevoer. CdK34pba kan 10 ppm sonsonderganggeel kleurstof uit ‘n EtOH oplosmiddel binne 24 uur by 40 °C onttrek. Die struktuur en termiese eienskappe van CdK34pba is ondersoek. Met behulp van sorpsie- en uitruileksperimente is die opnamekapasiteit van CdK34pba vir verskillende gaste bepaal. Verdere ondersoek moet ingestel word om onbeantwoorde vrae te verklaar. Masters 2020-02-20T10:20:34Z 2020-04-28T15:10:54Z 2020-02-20T10:20:34Z 2020-04-28T15:10:54Z 2020-02 Thesis http://hdl.handle.net/10019.1/108361 en_ZA Stellenbosch University xi, 127 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Crystallography Metal-organic frameworks Porous materials UCTD Wei, Xueting Characterisation and sorption study of a highly symmetrical porous metal-organic framework |
| title | Characterisation and sorption study of a highly symmetrical porous metal-organic framework |
| title_full | Characterisation and sorption study of a highly symmetrical porous metal-organic framework |
| title_fullStr | Characterisation and sorption study of a highly symmetrical porous metal-organic framework |
| title_full_unstemmed | Characterisation and sorption study of a highly symmetrical porous metal-organic framework |
| title_short | Characterisation and sorption study of a highly symmetrical porous metal-organic framework |
| title_sort | characterisation and sorption study of a highly symmetrical porous metal organic framework |
| topic | Crystallography Metal-organic frameworks Porous materials UCTD |
| url | http://hdl.handle.net/10019.1/108361 |
| work_keys_str_mv | AT weixueting characterisationandsorptionstudyofahighlysymmetricalporousmetalorganicframework |