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Synthesis and applications of novel azolium salts

Dallas, Andrea (2003) Synthesis and applications of novel azolium salts. PhD thesis, Dublin City University.

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The application of azole and azolium compounds is o f widespread interest both industrially and academically. There are many lively and diverse research areas employing these compounds, including organometallic processes, molecular recognition and biological research. Thus, the objective of this research was the preparation novel azolium salts and their application in some o f these areas. Ferrocenyl-imidazole and ferrocenyl-benzimidazole compounds and their respective salts were prepared and their catalytic, chemoreceptor and biological properties studied. Monosubstituted ferrocenyl-azolium salts (l-ferrocenylmethy-3-alkylazolium halides), acyclic bisazolium-ferrocenyl salts {l-[(l-ferrocenylmethyl-3-butyl)azolium]-3-ferrocenylmethylazolium diiodides and l,l'-bis(l-methyl-3-methylbenzimidazolium) ferrocenyl iodides} were synthesised. In addition, a very interesting macrocyclic benzimidazolium-ferrocenyl cyclophane was prepared - bis{l-[(l,r-ferrocenylmethyl-3-butyl)benzimidazolium]-3-ferrocenylmethyl}benzimidazolium tetraiodide. The action of these ferrocenyl-azolium salts as highly effective auxiliary ligands in transition metal-mediated catalysis was shown through catalytic studies using the Heck reaction. Furthermore, different catalytic efficiencies of benzimidazolium vs. imidazolium salts in the Heck reaction depending on the system was demonstrated in a comparitive study. In addition, l-butyl-3-methylimidazollium hexafluorophosphate was successfully employed as a recyclable, highly efficient solvent in the Heck reaction compared to DMF. Potential biological applications of these compounds include molecular recognition and antimicrobial studies. Coupling the redox active ferrocenyl unit with the cationic azolium nucleus allowed them to be realised as ionophores. Acyclic ferrocenyl-azolium salts demonstrated evidence o f anion co-ordination in ‘H NMR anion titration experiments. Also screening o f a range o f ferrocenyl-azole/azolium compounds against P. aeruginosa and C. albicans showed that azolium compounds with two ferrocene units in their structure had highly effective antifungal properties. Furthermore, a second co-ordination functionality was introduced into the ferrocenyl-azolium system. Thus, the preparation o f a 1,1 '-disubstituted ferrocenyl salt system with an imidazolium nucleus on one Cp ring and a diphenyl(sulphido)phosphine entity on the second Cp ring and a series of 1-ferrocenylmethylazole-diphenylphosphine functionalised compounds was carried out. Thus, developing a range o f compounds that show great potential as ligands.

Item Type:Thesis (PhD)
Date of Award:2003
Supervisor(s):Nolan, Kieran
Uncontrolled Keywords:azole; azolium compounds; preparation
Subjects:Physical Sciences > Chemistry
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:17201
Deposited On:17 Aug 2012 14:01 by Fran Callaghan. Last Modified 17 Aug 2012 14:01

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