Porosity studies of isoreticular mixed-ligand metal-organic frameworks
| dc.contributor.advisor | Oliver, Clive | |
| dc.contributor.author | Gcwensa, Nolwazi | |
| dc.date.accessioned | 2020-02-28T11:27:22Z | |
| dc.date.available | 2020-02-28T11:27:22Z | |
| dc.date.issued | 2019 | |
| dc.date.updated | 2020-02-28T08:54:09Z | |
| dc.description.abstract | The syntheses of four novel mixed-ligand metal-organic frameworks (MOFs) are reported. Isoreticular, Zn(II)-based mixed-ligand MOFs with formulae [Zn(μ2-ia)(μ2-bpe)]n·nDMF (1) and [Zn(μ2-mia)(μ2- bpe)]n·nDMF (2), where ia = isophthalate, mia = 5-methoxyisophthalate, bpe = 1,2-bis(4-pyridyl)ethane and DMF = N,N’-dimethylformamide were synthesised and characterised. Both compounds 1 and 2 exhibit sql, 2-periodic, 2D net coordination layers. Catenation of neighbouring frameworks form 2-fold interpenetrated bilayers which are interdigitated resulting in channel voids containing DMF. Experimental void calculations indicate 2′ has larger void space per unit cell than 1′; however, experimentally, 1′ showed higher water vapour and carbon dioxide 195 K sorption as well as significant hysteresis upon desorption of carbon dioxide 195 K. This hysteresis behaviour of 1′ is interchanged with 2′ for water vapour sorption at 298 K. Sorption isotherm inflection points indicate that structural changes occur, and empirical evidence point to weak bilayer···bilayer interactions in 1′ which allow the separation of the bilayers as well as the limiting effect on structural changes of the methoxy group present in 2′. Isoreticular mixed-ligand Cd(II)-based MOFs with formulae [Cd(μ2-mia)(μ2-bpe)1.5]n·n(DMF)0.5n(H2O)0.5 (3) and [Cd(μ2-nia)(μ2-bpee)1.5]n·nDMF (4), where nia = 5-nitroisophthalate and bpee = 1,2-bis(4-pyridyl)ethylene were also synthesised and characterised. Both compounds 3 and 4 exhibit sql, 2-periodic, 3D net coordination layers with disorder around a single bpe or bpee ligand. These structures are compared to published structure [Cd(bpee)1.5(nbdc)]n·nDMF (JECRAN) which is isoreticular to both MOFs. Activation of 4 and JECRAN occurs via single-crystal-to-single-crystal transformations. Potential and actual void space calculations indicate that 4′ has a larger void space than 3′ and JECROB. Liquid sorption experiments revealed that 3′ and 4′ showed affinities for different solvents. Although carbon dioxide 195 K sorption for 4′ is initially higher than for JECROB, structural changes, indicated by sorption isotherm inflection points, allow JECROB to adsorb more carbon dioxide than 4′ | |
| dc.identifier.apacitation | Gcwensa, N. (2019). <i>Porosity studies of isoreticular mixed-ligand metal-organic frameworks</i>. (). ,Faculty of Science ,Department of Chemistry. Retrieved from http://hdl.handle.net/11427/31385 | en_ZA |
| dc.identifier.chicagocitation | Gcwensa, Nolwazi. <i>"Porosity studies of isoreticular mixed-ligand metal-organic frameworks."</i> ., ,Faculty of Science ,Department of Chemistry, 2019. http://hdl.handle.net/11427/31385 | en_ZA |
| dc.identifier.citation | Gcwensa, N. 2019. Porosity studies of isoreticular mixed-ligand metal-organic frameworks. . ,Faculty of Science ,Department of Chemistry. http://hdl.handle.net/11427/31385 | en_ZA |
| dc.identifier.ris | TY - Thesis / Dissertation AU - Gcwensa, Nolwazi AB - The syntheses of four novel mixed-ligand metal-organic frameworks (MOFs) are reported. Isoreticular, Zn(II)-based mixed-ligand MOFs with formulae [Zn(μ2-ia)(μ2-bpe)]n·nDMF (1) and [Zn(μ2-mia)(μ2- bpe)]n·nDMF (2), where ia = isophthalate, mia = 5-methoxyisophthalate, bpe = 1,2-bis(4-pyridyl)ethane and DMF = N,N’-dimethylformamide were synthesised and characterised. Both compounds 1 and 2 exhibit sql, 2-periodic, 2D net coordination layers. Catenation of neighbouring frameworks form 2-fold interpenetrated bilayers which are interdigitated resulting in channel voids containing DMF. Experimental void calculations indicate 2′ has larger void space per unit cell than 1′; however, experimentally, 1′ showed higher water vapour and carbon dioxide 195 K sorption as well as significant hysteresis upon desorption of carbon dioxide 195 K. This hysteresis behaviour of 1′ is interchanged with 2′ for water vapour sorption at 298 K. Sorption isotherm inflection points indicate that structural changes occur, and empirical evidence point to weak bilayer···bilayer interactions in 1′ which allow the separation of the bilayers as well as the limiting effect on structural changes of the methoxy group present in 2′. Isoreticular mixed-ligand Cd(II)-based MOFs with formulae [Cd(μ2-mia)(μ2-bpe)1.5]n·n(DMF)0.5n(H2O)0.5 (3) and [Cd(μ2-nia)(μ2-bpee)1.5]n·nDMF (4), where nia = 5-nitroisophthalate and bpee = 1,2-bis(4-pyridyl)ethylene were also synthesised and characterised. Both compounds 3 and 4 exhibit sql, 2-periodic, 3D net coordination layers with disorder around a single bpe or bpee ligand. These structures are compared to published structure [Cd(bpee)1.5(nbdc)]n·nDMF (JECRAN) which is isoreticular to both MOFs. Activation of 4 and JECRAN occurs via single-crystal-to-single-crystal transformations. Potential and actual void space calculations indicate that 4′ has a larger void space than 3′ and JECROB. Liquid sorption experiments revealed that 3′ and 4′ showed affinities for different solvents. Although carbon dioxide 195 K sorption for 4′ is initially higher than for JECROB, structural changes, indicated by sorption isotherm inflection points, allow JECROB to adsorb more carbon dioxide than 4′ DA - 2019 DB - OpenUCT DP - University of Cape Town KW - Chemistry LK - https://open.uct.ac.za PY - 2019 T1 - Porosity studies of isoreticular mixed-ligand metal-organic frameworks TI - Porosity studies of isoreticular mixed-ligand metal-organic frameworks UR - http://hdl.handle.net/11427/31385 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/31385 | |
| dc.identifier.vancouvercitation | Gcwensa N. Porosity studies of isoreticular mixed-ligand metal-organic frameworks. []. ,Faculty of Science ,Department of Chemistry, 2019 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/31385 | en_ZA |
| dc.language.rfc3066 | eng | |
| dc.publisher.department | Department of Chemistry | |
| dc.publisher.faculty | Faculty of Science | |
| dc.subject | Chemistry | |
| dc.title | Porosity studies of isoreticular mixed-ligand metal-organic frameworks | |
| dc.type | Master Thesis | |
| dc.type.qualificationlevel | Masters | |
| dc.type.qualificationname | MSc |