The Synthesis Of A Water Soluble Porphyrin And The Mechanism Of The Formation Of Its Zinc Complex In Aqueous Solution

Author : John Lewis Jacobsen
Publisher :
ISBN 13 : 9781267240552
Total Pages : pages
Book Rating : 4.2/5 (45 download)

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Download or read book Synthesis and Applications of New Water-soluble Porphyrins and Explorations of Synthetic Routes to Quadrone written by John Lewis Jacobsen and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Porphyrins are attractive building blocks for self-assembled functional nanomaterials because they can be modified with a wide range of substituents and they possess diverse photophysical and chemical properties that are potentially useful in applications such as solar energy conversion, molecular electronics, catalysis and sensors. Recently, ionic self-assembly of oppositely-charged porphyrin tectons has been shown to produce well-defined structures such as nanotubes and nanofiber bundles. The synthesis of a novel cationic porphyrin tecton, tin 5,10,15,20-tetrakis(4-piperidyl)porphyrin is described. This porphyrin can be self-assembled with porphyrins such as 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin that only ionize under neutral or basic conditions. The nanostructures and metalized nanocomposites obtained from the self-assembly reactions are characterized using electron microscopy and spectroscopic techniques. In addition the synthesis and characterization of zinc and tin complexes of T(N-EtOH-Py)P are described and the ionic self-assembly reactions of these compounds to produce cooperative binary ionic solids are discussed. Quadrone's complex tetracyclic skeletal structure has allowed it to serve as an excellent showcase molecule for total synthesis. Three distinct routes were developed and tested in hopes of achieving an elusive substituted 10-hydroxy-dec-8-ynoic acid. Route I explored the limits of 1,4-conjugate addition. We were able to reproduce work demonstrating the remarkable selectivity that organomanganese reagents show for 1,4-addition even when the beta-carbon bears germinal-dimethyl substitution. Unfortunately, the propargylic manganese reagent needed for addition could not be synthesized despite using a diverse set of conditions and reagents. The second route demonstrated that an 11-membered acetylenic lactone could be transesterified into the corresponding methyl ester. This methyl ester resisted hydrolysis in the most forcing conditions commonly used. In fact decomposition of the molecule was observed before hydrolysis was ever observed. Route III utilized the Ireland-Claisen rearrangement (ICR) to generate the highly hindered tertiary carbon alpha to the geminal dimethyl carbons. The early troubles encountered in route III were particularly surprising given the large amount of general literature precedence available for the ICR and test systems were synthesized to explore the reaction in more detail. We demonstrated that the alpha-carbon must be relatively unhindered for the reaction to proceed. When the alpha-carbon is hindered, like most of our systems were, the desired rearrengement does occur but in low yield, and unusual side reactions are observed. In the system designed for the synthesis we observe an elimination reaction that consumes the majority of the starting material. When we truncated the system to prevent elimination, a coupled product was isolated that does not appear to have been fully characterized in the literature. Our early explorations into the formation of this coupled product indicate that some reaction control exists. By not adding TMS-Cl to the reaction we have successfully prevented the ICR while still allowing the coupling reaction to occur. Additionally, it appears possible to control which isomer of the coupled product forms either through reaction time or equivalents of base present. Ultimately, further work exploring the ICR of substrates containing quaternary beta-carbons needs to be done. Our initial test systems lead one to believe that this coupling process is not unique and that more substrates have the potential to form this complex functional group.