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Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions. / Matthew Lloyd Davies

Swansea University Author: Matthew Lloyd Davies

Abstract

The photophysics and thermal properties of a series of seven novel triarylamine (TAA) dyes are described. Fluorescence characteristics have been studied in solvents of various polarities at room temperature and at 77 K. High molar extinction coefficients of the magnitude of 3.0-4.0(+/-0.50)x104 M-1c...

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Published: 2010
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42510
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spelling 2018-08-02T16:24:29.5093962 v2 42510 2018-08-02 Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions. c6ab446ca479bb1ded5d7491c8b15903 NULL Matthew Lloyd Davies Matthew Lloyd Davies true true 2018-08-02 The photophysics and thermal properties of a series of seven novel triarylamine (TAA) dyes are described. Fluorescence characteristics have been studied in solvents of various polarities at room temperature and at 77 K. High molar extinction coefficients of the magnitude of 3.0-4.0(+/-0.50)x104 M-1cm-1 were obtained for most compounds, and relatively short radiative lifetimes were observed. Fluorescence quantum yields of the dyes at room temperature in cyclohexane were found to be between 0.34-0.57 increasing to 0.67-0.95 at 77 K. It has been shown that while at room temperature, solvent shell relaxation around the excited state can occur, and emission is from an equilibrium excited state to a twisted ground state, at 77 K in a rigid matrix environment solvent shell relaxation cannot occur and emission is from a Franck-Condon excited state to a planar ground state. The TAAs studied have excellent thermal properties for possible use in devices with thermal decomposition temperatures of greater than 300 &deg;C, they also do not crystallise readily. Three poly (9,9-bis[N,N-(trimethylammonium)hexyl] fluorene-co-l,4-phenylene), fluorescent cationic conjugated polymers (CCP), of average chain lengths- 6, 12 and 100 repeat units, and their interaction with DNA and guanine are reported. Fluorescence microscopy and atomic force microscopy have been utilised to visualise the interaction between the polymers and DNA. Results show both efficient compaction of DNA induced by the polymer and linking and bridging of DNA/polymer aggregates. CCPs are known to aggregate in water, and for the CCPs studied here this is reflected in a decrease in fluorescence. These aggregates can be broken up by mixtures of solvents, e.g. acetonitrile/water. Steady state and ps time resolved techniques have been used to study: (i) aggregation of CCPs in various acetonitrile/water mixtures, and (ii) fluorescence quenching by single and double strand DNA, and guanine. All CCPs are extremely sensitive to quenching by DNA or guanine, with sensitivity increasing with chain length of both the CCP and DNA. Stem-Volmer plots are sigmoidal and have initial quenching rates constants far in excess of the diffusion controlled limit. The results have been analysed in terms of energy migration and trapping within and between polymer chains. Quenching seems best analysed in terms of an equilibrium in which a CCP/DNA aggregate complex is formed which brings polymer chains into close enough proximity to allow interchain excitation energy migration and quenching at aggregate or DNA base traps. We also report preliminary results of modelling time resolved data, of both the aggregation and quenching, using a kinetic model in which energy migration and trapping are represented as a series of energy transfer steps between neighbours. E-Thesis Biochemistry. 31 12 2010 2010-12-31 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:29.5093962 2018-08-02T16:24:29.5093962 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Matthew Lloyd Davies NULL 1 0042510-02082018162500.pdf 10801740.pdf 2018-08-02T16:25:00.1800000 Output 12025634 application/pdf E-Thesis true 2018-08-02T16:25:00.1800000 false
title Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions.
spellingShingle Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions.
Matthew Lloyd Davies
title_short Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions.
title_full Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions.
title_fullStr Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions.
title_full_unstemmed Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions.
title_sort Photophysical studies of triarylamine dyes and an investigation into polyelectrolyte-DNA interactions.
author_id_str_mv c6ab446ca479bb1ded5d7491c8b15903
author_id_fullname_str_mv c6ab446ca479bb1ded5d7491c8b15903_***_Matthew Lloyd Davies
author Matthew Lloyd Davies
author2 Matthew Lloyd Davies
format E-Thesis
publishDate 2010
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
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description The photophysics and thermal properties of a series of seven novel triarylamine (TAA) dyes are described. Fluorescence characteristics have been studied in solvents of various polarities at room temperature and at 77 K. High molar extinction coefficients of the magnitude of 3.0-4.0(+/-0.50)x104 M-1cm-1 were obtained for most compounds, and relatively short radiative lifetimes were observed. Fluorescence quantum yields of the dyes at room temperature in cyclohexane were found to be between 0.34-0.57 increasing to 0.67-0.95 at 77 K. It has been shown that while at room temperature, solvent shell relaxation around the excited state can occur, and emission is from an equilibrium excited state to a twisted ground state, at 77 K in a rigid matrix environment solvent shell relaxation cannot occur and emission is from a Franck-Condon excited state to a planar ground state. The TAAs studied have excellent thermal properties for possible use in devices with thermal decomposition temperatures of greater than 300 &deg;C, they also do not crystallise readily. Three poly (9,9-bis[N,N-(trimethylammonium)hexyl] fluorene-co-l,4-phenylene), fluorescent cationic conjugated polymers (CCP), of average chain lengths- 6, 12 and 100 repeat units, and their interaction with DNA and guanine are reported. Fluorescence microscopy and atomic force microscopy have been utilised to visualise the interaction between the polymers and DNA. Results show both efficient compaction of DNA induced by the polymer and linking and bridging of DNA/polymer aggregates. CCPs are known to aggregate in water, and for the CCPs studied here this is reflected in a decrease in fluorescence. These aggregates can be broken up by mixtures of solvents, e.g. acetonitrile/water. Steady state and ps time resolved techniques have been used to study: (i) aggregation of CCPs in various acetonitrile/water mixtures, and (ii) fluorescence quenching by single and double strand DNA, and guanine. All CCPs are extremely sensitive to quenching by DNA or guanine, with sensitivity increasing with chain length of both the CCP and DNA. Stem-Volmer plots are sigmoidal and have initial quenching rates constants far in excess of the diffusion controlled limit. The results have been analysed in terms of energy migration and trapping within and between polymer chains. Quenching seems best analysed in terms of an equilibrium in which a CCP/DNA aggregate complex is formed which brings polymer chains into close enough proximity to allow interchain excitation energy migration and quenching at aggregate or DNA base traps. We also report preliminary results of modelling time resolved data, of both the aggregation and quenching, using a kinetic model in which energy migration and trapping are represented as a series of energy transfer steps between neighbours.
published_date 2010-12-31T03:53:06Z
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score 11.035874

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