Browsing by Author "Batisai, Eustina"
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- ItemPreparation and coordination chemistry of bis-pyridyl diamide ligands(Stellenbosch : University of Stellenbosch, 2010-03) Batisai, Eustina; Barbour, Leonard J.; Le Roex, Tanya; University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science.ENGLISH ABSTRACT: The number of coordination complexes utilizing bis-pyridyl diamide ligands has increased significantly over the past decade. This is attributed to the relatively easy synthetic procedure of the ligands and interesting structural features such as helicity, water clusters and porosity that the coordination complexes possess. In the first part of this study, the following eight structurally related bis-pyridyl diamide ligands: • N,N'-bis(pyridin-4-ylmethyl)isophthalamide (ISO); • N,N'-bis(pyridyl-4-ylmethyl)terephthalamide (TER); • N,N'-bis(pyridin-4-ylmethyl)hexanediamide (ADI); • N,N'-bis(pyridin-4-ylmethyl)butanediamide (SUC); • N,N'-bis(pyridin-4-ylmethyl)biphenyl-4,4'-dicarbonyl dicarboxamide (DIP); • N,N'-dipyridin-2-ylpentanediamide (GLUT); • (2E)-N,N'-bis(2-pyridin-4-ylmethyl)but-2-enediamide (FUM); • 4-(pyridin-4-ylmethyl)aminocarbonyl benzoic acid (TER-A). were synthesized and characterized by NMR, FTIR, MS and SCD. In the second part, the synthesized ligands were reacted with a variety of transition metal salts to yield fifteen novel coordination polymers and one discrete complex. SCD analysis showed that of the sixteen complexes thirteen formed 1-D chains, two formed 2-D networks, and one formed a discrete unit. Hydrogen bonding interactions between water molecules, the counterions and the amide groups resulted in connection of the lower dimension entities into higher dimension networks. The synthesized ligands were co-crystallized with trimesic acid and a novel co-crystal consisting of ADI and trimesic acid was obtained. SCD analysis showed that the co-crystal featured the amide homosynthon as well as the pyridine/carboxylic acid heterosynthon.
- ItemSynthesis and sorption studies of porous metal-organic hosts(Stellenbosch : Stellenbosch University, 2013-03) Batisai, Eustina; Barbour, Leonard J.; Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science.ENGLISH ABSTRACT: The first part of this study describes the synthesis of new porous materials from basic building blocks. Five structurally related ligands namely: N,N'-bis(3-pyridylmethyl)-naphthalene diimide (L1), N,N'-bis(4-pyridylmethyl)-naphthalene diimide (L2), N,N'-bis(4-pyridylmethyl)- pyromellitic diimide (L3), N,N'-bis(3-pyridylmethyl)-pyromellitic diimide (L4) and 2-(pyridin-4- ylmethyl)-benzene tricarboxylic anhydride (L5) were synthesised. Ligands L1 and L2 were reacted with metal nitrates and carboxylates as co-ligands in a systematic manner with a view to obtaining potentially porous 3–D coordination polymers. Ten structurally diverse coordination polymers were obtained and they were characterised by single-crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analysis. Four of these compounds absorb moderate amounts of CO2 and, in addition, show sorption selectivity towards CO2 over N2. The reaction of L3 and L4 with transition metal halides yielded two 1–D chains, while the reaction of L5 with transition metal nitrates yielded seven coordination polymers of which four are 2–D and three are 1–D. Of the 2–D structures three are isostructural. The second part of this work describes a variable pressure study of a flexible metal-organic framework [Zn2(BDC)2(BPY)] (BPY = 4,4 -bipyridine and BDC = 1,4-benzene dicarboxylic acid). [Zn2(BDC)2(BPY)] is one of the few examples of a flexible metal-organic framework that undergoes phase transformations in response to gas pressure. The high pressure sorption recorded for this metal-organic framework displays two inflection steps in the pressure range 0 to 30 bar, possibly indicating two phase transformations. The gas-loaded structures for each phase transformation were determined by means of single-crystal X-ray diffraction. High-pressure differential scanning calorimetry was also carried out on the system in order to determine accurate gate-opening pressures, as well as the energies involved with each phase transformation. The results correlate with those obtained from single-crystal X-ray diffraction and high-pressure sorption. The final section reports the mechanochemical synthesis of two Werner complexes [NiCl2(4- PhPy)4] (1), [CoCl2(4-PhPy)4] (2) and their corresponding solid solution [Ni0.5Co0.5Cl2(4-PhPy)4] (3) (PhPy = phenyl pyridine). The solid solution could only be formed by mechanochemical synthesis and not by conventional solution crystallisation methods. The solid solution exhibits sorption properties that differ from those of the pure compounds.