Heterocyclic Calix[4]arene Derivatives for Fluorescence Investigations


Maher, Niall (2013) Heterocyclic Calix[4]arene Derivatives for Fluorescence Investigations. PhD thesis, National University of Ireland Maynooth.

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Abstract

This project entails the synthesis of a family of novel Schiff base capped calix[4]arenes. These ligands were prepared using three 1,3 bis-bromo-alkyl-disubstituted calix[4]arenes (ethyl, propyl and butyl), and ortho, meta and para substituted di-imine bridged diphenol units. All these reactions yielded the desired product with the exception of the bis-bromoethyl variants which did not result in capped calix[4]arene formation. The resulting ligands were subjected to attempted metal complexation reactions with metal perchlorate salts (Cu2+, Co2+, Hg2+, Ni2+ and Zn2+) and all these reactions resulted in hydrolysis of the imine moiety. Evidence of metal complexation was noted in some cases and it is thought that ethylenediamine metal (en(M)) chelate complexes have formed. A class of novel 1,3 bis-triazole linked calix[4]arene benzaldehydes were prepared through difunctionalisation of the lower rim. A zinc(II) perchlorate complex of one of these was formed and the binding site was evaluated using 1H and 13C NMR spectroscopy. The fluorescent behaviour of two of these ligands was probed with a view to use as a fluorescent chemosensor. However, it was determined that this class of compounds was unsuitable for this role. The synthesis of a range of triazole linked Schiff base capped calix[4]arenes was attempted, but it was discovered the imine moiety was incompatible with the conditions used for triazole formation. A novel bis-propargyl di-imine diphenol precursor was prepared from the meta Schiff base linker. Finally anthracene and pyrene isoxazole calix[4]arenes sensors were prepared in collaboration with the Heaney group of NUI Maynooth. The fluorescent emission spectra of these were recorded, and the effect a range of metal cations (Cd2+, Co2+, Cu2+, Fe2+, Hg2+, Pb2+ and Zn2+) had on the spectra was recorded. The calix[4]arene based sensors should good selectivity for Cu2+ cations. Exploitation of fluorescence spectroscopic methods led to the determination of the stoichiometry (1:1) and binding constant for these chemosensors. The mode of binding was also examined by 1H NMR spectra titration studies, and through molecular modelling studies which provides a coordination geometrical explanation of the selectivity for Cu2+.

Item Type: Thesis (PhD)
Keywords: Heterocyclic Calix[4]arene Derivatives; Fluorescence Investigations;
Academic Unit: Faculty of Science and Engineering > Chemistry
Item ID: 6747
Depositing User: IR eTheses
Date Deposited: 07 Jan 2016 17:18
URI:

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