The synthesis of cavitand-capped porphyrin ligands, with a view towards their potential as ligands in homogeneous catalysis, is described. The ligand apertures, one of which is outlined in the figure below, are focal with the aim of synthesising a ligand which can control access to the active site of the porphyrin via these apertures Synthesis of the target ligand (where R' = CH2 in the figure presented) was attempted via two pathways. Synthesis commenced by using an in situ protocol, which used successive functionalisation of the cavitand structure towards the required aldehyde precursor for porphyrin formation. It was found that subsequent in situ cyclisation and porphyrin formation was hindered by steric factors, arising directly from the short -CH2O- bridges used to link the cavitand to the porphyrin. Ligand synthesis was thus unsuccessful. In a second approach, the porphyrin was synthesised in isolation before being coupled with the cavitand in a direct capping protocol, which gave more promising results. In the case of R = C11H23 (in the figure above), preliminary UV-Vis analysis indicated a successful synthesis. Subsequent analysis of the reaction product by NMR techniques and mass spectrometry could not conclusively confirm the synthesis of the target ligand. The synthesis could therefore not be deemed a success; conceivably the short bridge length being the decisive factor once more. Computational chemistry was used to investigate synthetic results, and therefore the viability of using the -CH2O- bridges to afford limited access to the porphyrin active site. By using molecular mechanics, -CH2O- bridges were found to be too short, giving an aperture of insufficient size to enable only the terminus of a linear paraffin to gain access to the inner cavity of the ligand. Further investigation using molecular dynamics indicated that a ligand bearing bridges four or five atoms in length would afford an aperture of the desired size to accommodate the terminus of a paraffin exclusively. Consequently, synthesis was redesigned towards the preparation of two new ligands, bearing - O(CH2)2O- (four atom, R' = O(CH2)2 in the figure above) and -O(CH2)3O- (five atom, R' = O(CH2)3 in the figure above) bridges. Using 2-phenylethyl feet (R = CH2CH2C6H5 in the figure presented) and adopting the in situ synthetic protocol, both ligands were successfully synthesised. Characterisation using UV-Vis and NMR spectroscopic techniques, as well as mass spectrometry confirmed that both ligands had been obtained pure. Additionally, the in situ cyclisation (in both ligands) was performed via the use of microwave heating, a technique hitherto unreported. A viable synthetic route was thus established for the preparation of two new cavitand-capped porphyrin ligands towards their use in size-selective catalysis. In addition, a number of crystal structures of synthetic intermediates are described, five of which are newly reported. These illustrated notable structural features regarding resorcin[4]arene cavitands and their abilities as host molecules. In particular, the structure of the aldehyde precursor to capped porphyrin formation following the (initial) in situ synthetic protocol was significant in illustrating the reason as to why in situ cyclisation was unsuccessful for the synthesis involving -CH2O- bridges. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2008.

Thesis (MSc)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Thesis (Ph.D.) in Chemistry--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 263-273).

Thesis (Ph. D.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 113-117).

Thesis (M.S.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2005. / Kubanek, Julia, Committee Member ; Collard, David, Committee Member ; Shuker, Suzanne, Committee Chair. Includes bibliographical references.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2009. / Committee Chair: Weck, Marcus; Committee Member: Breedveld, Victor; Committee Member: Bunz, Uwe; Committee Member: Liotta, Charles; Committee Member: Marder, Seth; Committee Member: Srinivasarao, Mohan. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Feb. 17, 2009). PDF text: xii, 219 p. : ill. (some col.) ; 5 Mb. UMI publication number: AAT 3328256. Includes bibliographical references. Also available in microfilm and microfiche formats.

Over the past quarter of a century a vast amount of research investigating the synthesis and properties of mechanically interlocked molecules has been reported. This can be largely attributed to the emergence of non-statistical, supramolecular strategies for their synthesis, starting with Jean-Pierre Sauvage’s metal template capture of a catenane – a single molecule comprising two macrocycles which could not be unlinked without breaking a covalent bond. Other molecules possessing interlocked architectures, namely rotaxanes and knots, have also been synthesised and studied. While a variety of other template strategies have been developed over the years, the use of metal ions remains popular and widespread amongst supramolecular chemists due to their diversity as both templates and catalysts. The research presented in this thesis explores that remarkable diversity, demonstrating the rapid progress that has been achieved towards the synthesis of increasingly complex molecules by the continued usage of metal template strategies. Chapter 1 reviews the current state of the art regarding metal template synthesis of mechanically interlocked molecules. Chapter 2 reports the synthesis of doubly-interlocked [2]catenanes (otherwise known as Solomon links) from supramolecular interwoven 2×2 grids. Chapter 3 details progress towards the synthesis of an “endless” knot with seven crossings from an unprecedented interwoven 3×3 grid. Chapter 4 illustrates the use of a circular iron(II) double helicate to construct a highly compact and complex molecular knot with eight crossings. Chapter 5 describes an active metal template strategy for the synthesis of the first [4]rotaxanes containing one ring and three threads.

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