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Title: Time resolved fluorescence and pH sensing studies of electropolymerised 5-substituted indoles
Author: Williams, Alice E.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2005
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In this thesis electropolymerised samples of the 5-cyanoindole and 5-bromoindole were studied. Steady state fluorescence and Time Correlated Single Photon Counting experiments were performed on solutions in ethanol of both types of polymer, and potentiometric experiments to ascertain the pH sensing ability of 5-cyanoindole solid films were carried out. The potential of rotating disc electrodes modified with thick (1.37μm) and thin (0.49μm) films 5-cyanoindole polymer were found to respond to changes in electrolyte pH linearly with a near-Nernstian slope, which is indicative of a promising pH sensing material. The response was independent of direction of pH change and sustainable over a time period of at least a week. The thin film shored promise as a good fast response pH sensor. Steady State (SS) fluorescence spectroscopy experiments carried out on solutions of electropolymerised 5-cyanoindole in ethanol at room temperature have shown that, when exciting at short wavelength the trimer chromophore gives the most intense emission at short wavelength, with no emission seen at longer wavelengths, and no noticeable difference between samples produced to produce trimer-rich and more extensively linked films. Exciting at longer wavelength a slight difference between the emission intensities of higher polymer and higher trimer content films was observed. Time Correlated Single Photon Counting (TCSPC) experiments were carried out at excitation wavelengths 360nm and 450nm and it was seen that the free trimer chromophore was the dominant contributor to the excited state population at all wavelengths. SS experiments were carried out on solutions of electropolymerised 5-bromoindole in ethanol and, consistent with previous work, it was seen that higher intensity of emission was seen in the polymeric region at longer emission wavelength. Additionally a marked difference was seen between higher and lower polymer content films.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available