Investigation of four roof-shaped host compounds for their separation potential of mixtures of guest Isomers and related compounds
- Authors: Senekal, Ulrich
- Date: 2024-04
- Subjects: Grignard reagents , Optical isomers -- Analysis , Supramolecular chemistry
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64368 , vital:73684
- Description: The inclusion ability of four roof-shaped host compounds, namely trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylic acid (H1), dimethyl trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylate (H2), trans-α,α,α’,α’-tetraphenyl-9,10-dihydro-9,10- ethanoanthracene-11,12-dimethanol (H3) and trans-α,α,α’,α’-tetrakis(4-chlorophenyl)-9,10- dihydro-9,10-ethanoanthracene-11,12-dimethanol (H4), were investigated when presented with numerous guest series (eight in number), including the xylene isomers and ethylbenzene, pyridine and the methylpyridine isomers, structurally related toluene, ethylbenzene and cumene, the dichlorobenzenes, six-membered heterocyclic ring compounds (dioxane, morpholine, piperidine and pyridine), anisole and the methylanisole isomers, anisole and the bromoanisole guests, and phenol and the methoxyphenol isomers. The four host compounds were synthesized via Diels-Alder (H1), esterification (H2) and Grignard addition (H3 and H4) reactions, producing yields of product of up to 93%. The yields for the Grignard reactions were lower, 54 and 37%, for the corresponding procedures using phenylmagnesium bromide or 4-chlorophenylmagnesium bromide. Computational molecular modelling studies were conducted on all four host compounds, and the resultant molecular geometries compared with the apohost (guest-free) crystal structures, when available. The geometries of the lowest energy conformers were in close correlation with the observed host structures as obtained from the apohost crystal structures (unfortunately, H3 and H4 were not able to form adequate quality crystals for SCXRD analyses). Interestingly, H1–H4 displayed intramolecular non-classical C–H∙∙∙O hydrogen bonds, while only H1 and H2 demonstrated intermolecular interactions of this type. H3 and H4 assumed one of two forms depending on the guest that was employed: the “active” form presented a strong intramolecular O–H∙∙∙O hydrogen bond, while the “inactive” form possessed weak π∙∙∙π and O–H∙∙∙π interactions. All of the host compounds were subjected to crystallization experiments from each of the guest species, as well as from mixtures of guests from each series (the guest competition experiments), where 1H-, 13C-NMR spectroscopy, GC-MS and/or GC-FID were used to analyse any resultant solids formed, as applicable. Single crystal X-ray diffraction (SCXRD) experiments were carried out on each single solvent complex produced in this work, where the crystal quality was suitable, while thermal analyses were also employed on these to determine their relative thermal stabilities. During the single-guest crystallization experiments, H4 was found to be remarkable in its inclusion ability, forming complexes with all but p-dichlorobenzene, typically with a 1:1 host:guest (H:G) ratio. H1 was more selective in its inclusion behaviour, not enclathrating cumene, 3-bromoanisole, phenol or the three methoxyphenol isomers (favouring 1:1 or 2:1 H:G ratios where complexation was successful). Interestingly, H1 formed salts when presented with 2- and 3-methylpyridine, and morpholine and piperidine. H2 and H3 were less remarkable in their inclusion ability, furnishing apohost crystals or gels in some experiments (typically a 3:1 H:G ratio was favoured for both when complexation occurred). Of the four roof-shaped host compounds, H1 and H4 displayed enhanced selectivities for certain guest species, showing near-complete affinity for a specific guest compound when presented with a guest mixture. H1 was able to include 100.0 and 98.8% p-dichlorobenzene (p-DCB) (from m-DCB/p-DCB and o-DCB/p-DCB mixtures), 96.6 and 93.6% p-xylene (p-Xy) (from m-Xy/p-Xy and o-Xy/p-Xy), 99.3% 4-methylanisole (4-MA) (from 2-MA/4-MA) and 97.1% 4-bromoanisole (4-BA) (from ANI/2-BA/3-BA/4-BA, where ANI is anisole). Host compound H4 was able to include ≈ 90% of selected meta-substituted guests, while H2 and H3 demonstrated moderate preferences for the guest compounds employed in this work (< 60%). It was concluded that some xylene guest mixtures may be purified using all but H2, whereas only H1 and H2 showed potential in separating the pyridines. All but H2 may also be employed in the separation of selected dichlorobenzene mixtures, while H2 showed potential for the separation of the six-membered heterocyclic guest compounds (dioxane, morpholine, piperidine and pyridine), were these ever required to be separated. Both H1 and H4 exhibited an overwhelming affinity for the methyl- and bromoanisole guest compounds, and this work has shown that these are likely host candidates for the purification of a variety of these guest mixtures through supramolecular strategies. SCXRD analyses showed that H1 experienced intermolecular host···host hydrogen bonding interactions between the carboxylic acid functional groups, while H2 typically demonstrated intermolecular non-classical hydrogen bonds in its complexes, forming sheets of host molecules along the c-axis. H4 preferred the “inactive” form whereas H3 assumed either an “active” or “inactive“ form. Various host···guest interactions such as π∙∙∙π, C–H∙∙∙π, C–O∙∙∙π, hydrogen bonding and other short contacts were responsible for guest retention in the crystal structures. Thermal analyses were conducted on all of the successfully formed complexes. Ton (the guest release onset temperature) and Tp (the temperature at which the guest release was most rapid) were recorded, when possible, while the mass losses associated with the guest release event were compared with those mass losses expected, in most cases. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Senekal, Ulrich
- Date: 2024-04
- Subjects: Grignard reagents , Optical isomers -- Analysis , Supramolecular chemistry
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64368 , vital:73684
- Description: The inclusion ability of four roof-shaped host compounds, namely trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylic acid (H1), dimethyl trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylate (H2), trans-α,α,α’,α’-tetraphenyl-9,10-dihydro-9,10- ethanoanthracene-11,12-dimethanol (H3) and trans-α,α,α’,α’-tetrakis(4-chlorophenyl)-9,10- dihydro-9,10-ethanoanthracene-11,12-dimethanol (H4), were investigated when presented with numerous guest series (eight in number), including the xylene isomers and ethylbenzene, pyridine and the methylpyridine isomers, structurally related toluene, ethylbenzene and cumene, the dichlorobenzenes, six-membered heterocyclic ring compounds (dioxane, morpholine, piperidine and pyridine), anisole and the methylanisole isomers, anisole and the bromoanisole guests, and phenol and the methoxyphenol isomers. The four host compounds were synthesized via Diels-Alder (H1), esterification (H2) and Grignard addition (H3 and H4) reactions, producing yields of product of up to 93%. The yields for the Grignard reactions were lower, 54 and 37%, for the corresponding procedures using phenylmagnesium bromide or 4-chlorophenylmagnesium bromide. Computational molecular modelling studies were conducted on all four host compounds, and the resultant molecular geometries compared with the apohost (guest-free) crystal structures, when available. The geometries of the lowest energy conformers were in close correlation with the observed host structures as obtained from the apohost crystal structures (unfortunately, H3 and H4 were not able to form adequate quality crystals for SCXRD analyses). Interestingly, H1–H4 displayed intramolecular non-classical C–H∙∙∙O hydrogen bonds, while only H1 and H2 demonstrated intermolecular interactions of this type. H3 and H4 assumed one of two forms depending on the guest that was employed: the “active” form presented a strong intramolecular O–H∙∙∙O hydrogen bond, while the “inactive” form possessed weak π∙∙∙π and O–H∙∙∙π interactions. All of the host compounds were subjected to crystallization experiments from each of the guest species, as well as from mixtures of guests from each series (the guest competition experiments), where 1H-, 13C-NMR spectroscopy, GC-MS and/or GC-FID were used to analyse any resultant solids formed, as applicable. Single crystal X-ray diffraction (SCXRD) experiments were carried out on each single solvent complex produced in this work, where the crystal quality was suitable, while thermal analyses were also employed on these to determine their relative thermal stabilities. During the single-guest crystallization experiments, H4 was found to be remarkable in its inclusion ability, forming complexes with all but p-dichlorobenzene, typically with a 1:1 host:guest (H:G) ratio. H1 was more selective in its inclusion behaviour, not enclathrating cumene, 3-bromoanisole, phenol or the three methoxyphenol isomers (favouring 1:1 or 2:1 H:G ratios where complexation was successful). Interestingly, H1 formed salts when presented with 2- and 3-methylpyridine, and morpholine and piperidine. H2 and H3 were less remarkable in their inclusion ability, furnishing apohost crystals or gels in some experiments (typically a 3:1 H:G ratio was favoured for both when complexation occurred). Of the four roof-shaped host compounds, H1 and H4 displayed enhanced selectivities for certain guest species, showing near-complete affinity for a specific guest compound when presented with a guest mixture. H1 was able to include 100.0 and 98.8% p-dichlorobenzene (p-DCB) (from m-DCB/p-DCB and o-DCB/p-DCB mixtures), 96.6 and 93.6% p-xylene (p-Xy) (from m-Xy/p-Xy and o-Xy/p-Xy), 99.3% 4-methylanisole (4-MA) (from 2-MA/4-MA) and 97.1% 4-bromoanisole (4-BA) (from ANI/2-BA/3-BA/4-BA, where ANI is anisole). Host compound H4 was able to include ≈ 90% of selected meta-substituted guests, while H2 and H3 demonstrated moderate preferences for the guest compounds employed in this work (< 60%). It was concluded that some xylene guest mixtures may be purified using all but H2, whereas only H1 and H2 showed potential in separating the pyridines. All but H2 may also be employed in the separation of selected dichlorobenzene mixtures, while H2 showed potential for the separation of the six-membered heterocyclic guest compounds (dioxane, morpholine, piperidine and pyridine), were these ever required to be separated. Both H1 and H4 exhibited an overwhelming affinity for the methyl- and bromoanisole guest compounds, and this work has shown that these are likely host candidates for the purification of a variety of these guest mixtures through supramolecular strategies. SCXRD analyses showed that H1 experienced intermolecular host···host hydrogen bonding interactions between the carboxylic acid functional groups, while H2 typically demonstrated intermolecular non-classical hydrogen bonds in its complexes, forming sheets of host molecules along the c-axis. H4 preferred the “inactive” form whereas H3 assumed either an “active” or “inactive“ form. Various host···guest interactions such as π∙∙∙π, C–H∙∙∙π, C–O∙∙∙π, hydrogen bonding and other short contacts were responsible for guest retention in the crystal structures. Thermal analyses were conducted on all of the successfully formed complexes. Ton (the guest release onset temperature) and Tp (the temperature at which the guest release was most rapid) were recorded, when possible, while the mass losses associated with the guest release event were compared with those mass losses expected, in most cases. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
Novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine: an investigation of their inclusion ability
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
- Authors: Senekal, Ulrich
- Date: 2019
- Subjects: Microbiology -- Research , Organic compounds -- Environmental aspects Natural products -- Synthesis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43644 , vital:36952
- Description: The closely related and novel host compounds N,N’-bis(9-cyclohexyl-9-xanthenyl)ethylenediamine (103) and N,N’-bis(9-cyclohexyl-9-thioxanthenyl)ethylenediamine (104) were investigated for their host ability in the presence of various potential organic guest solvent series’. These hosts were readily synthesized from xanthone and thioxanthone, respectively, in low to adequate yields of >33%. Initially, the hosts 103 and 104 were subjected to a computational study, and these results compared with the geometries of these molecules from the apohost crystal structures. Differences were noted, and the geometry of 103 in the crystal resembled more closely the geometry of the second lowest energy conformer, while that of 104 resembled the third lowest calculated conformer. However, striking was the difference in geometry of the two apohost molecules from the crystal structures, despite their only variance being the heteroatom in the B ring. The significant differences were noted in both the orientation of the cyclohexyl and xanthenyl moieties, and in the ethylenediamine linker. Three organic guest solvent series’ were investigated here, including pyridine and its methylpyridine isomers, ethylbenzene and the xylene isomers, and the six-membered heterocyclic ring guests pyridine, dioxane, morpholine and piperidine. 1H-NMR spectroscopy and/or GC-MS were employed in the analyses of all experiments, as applicable, while thermal and single crystal diffraction analyses were performed on all successfully-formed complexes of suitable crystal quality that resulted from the single solvent experiments. From these single solvent experiments, where the host was recrystallized from each individual guest solvent, it was observed that 103 was a very efficient host in the presence of these guests, while 104 fared less well. Host 103 was able to clathrate all of the considered guests with the exception of 2-methylpyridine and m-xylene. Host 104, on the other hand, was only able to successfully clathrate the heterocyclic pyridine, dioxane, morpholine and piperidine solvents. Competition experiments were also conducted, where the hosts were presented with mixed guests, in order to determine whether they displayed any selective behaviour. It was observed that 103 was indeed selective in the presence of the pyridine/methylpyridine, xylene/ethylbenzene and heterocyclic guest series’. Selectivity orders of 92.8% 4-methylpyridine >> 6.0% pyridine > 0.9% 3-methylpyridine > 0.3% 2-methylpyridine, 49.2% o-xylene > 24.8% p-xylene > 17.9% ethylbenzene > 8.1% m-xylene, and 55.7% morpholine > 24.1% dioxane > 15.0% piperidine > 5.2% pyridine were noted for this host. Host 104, on the other hand, did not form complexes when it was recrystallized from the pyridine/methylpyridine and xylene/ethylbenzene guest mixtures. However, the heterocyclic guest mixtures did furnish complexes, and a selectivity order of 32.9% morpholine > 30.0% piperidine > 22.2% dioxane > 14.9% pyridine was obtained. Single crystal diffraction analyses showed that the 103•2(4-methylpyridine) complex, containing the most favoured substituted pyridine guest of 103, was the only one to experience a hydrogen bond between host and guest molecules, explaining the high preference of this guest by 103. Thermal data were obtained for all but two complexes: 103•PIP and 4(104)•3(DIO) experienced complete guest loss during sample preparation. The guest release onset temperatures of the other complexes, indicative of relative thermal stability, did not always correlate with the selectivity orders that were obtained from competition experiments.
- Full Text:
- Date Issued: 2019
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