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Synthesis and reactions of organometallic porphyrins

Atefi, Farzad (2007) Synthesis and reactions of organometallic porphyrins. PhD thesis, Queensland University of Technology.

Abstract

This thesis reports progress in three major aspects of σ-bonded organometallic porphyrins that are described in the published papers found in chapters 4, 5 and 6. meso-Iodoporphyrins, which were prepared in a rapid, selective and high yielding methodology from the respective 1-palladioporphyrins or bromoporphyrins, are important starting materials for further functionalisations of porphyrins. Their utility was confirmed in a palladium-catalysed coupling reaction and this novel synthetic strategy could potentially be applied for iodine/bromine exchange on other organic substrates..

A 1-palladioporphyrin was also utilised to optimise the reaction conditions leading to the formation of porphyrinylphosphine oxides. This synthetic strategy simplified the challenging optimisation of the palladium-catalysed reaction and has great potential to be applied in other catalytic processes. Subsequently a suite of porphyrinylphosphine oxides was prepared under the optimised catalytic conditions. These macrocycles, which represent a new class of porphyrins, were isolated cleanly in very high yields. Detailed spectroscopic investigations as well as X-ray single crystal analysis demonstrated their structures unambiguously and established their potential as ligands for supramolecular chemistry.

The coordinating properties of phosphine oxides in general and porphyrinylphosphine oxides in particular, towards Mg(II) centred porphyrins were examined in further experiments. Triphenylphosphine oxide showed a strong affinity towards Mg(II) porphyrins and the calculated displacement constant of 5.3 × 105 M-1 was two orders of magnitude larger than any other Mg(II) porphyrin-ligand binding constant reported thus far. Di- and triporphyrin arrays consisting of Mg(II) porphyrin coordinated to free base and Ni(II) porphyrinyl mono- and bis-phosphine oxides were also prepared in high yields. Spectroscopic studies indicated that these porphyrin oligomers exhibit strong inter-porphyrin electronic interaction.

A Mg(II) porphyrinylphosphine oxide dimer was also isolated in a satisfactory yield. The large self-association constant of 5.5 × 108 M-1 confirmed the strong affinity of porphyrinylphosphine oxides towards Mg(II) porphyrins and established these complexes as the first strongly bound synthetic Mg(II) porphyrin analogues of the "special pair" of the photosynthetic reaction centre.

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ID Code: 17563
Item Type: QUT Thesis (PhD)
Supervisor: Arnold, Dennis& McMurtrie, John
Keywords: porphyrinoids, iodination, palladium, organometallic, crystal structure, ligand design, phosphine oxides, oligomers, special pair, photosynthesis
Divisions: Past > QUT Faculties & Divisions > Faculty of Science and Technology
Past > Schools > School of Physical & Chemical Sciences
Institution: Queensland University of Technology
Deposited On: 06 Feb 2009 12:23
Last Modified: 29 Oct 2011 05:51

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