Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems
This dissertation focuses on the applicability of a variety of time-resolved spectroscopic techniques to probe the excited state photophysics of a range of biologically and environmentally relevant systems.;Hypericin, a biologically active perylene quinone and an efficient photosensitizing agent has...
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ftiowastateuniv:oai:lib.dr.iastate.edu:rtd-1765 2023-05-15T18:26:53+02:00 Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems Chowdhury, Pramit Kumar 2004-01-01T08:00:00Z application/pdf https://lib.dr.iastate.edu/rtd/766 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1765&context=rtd en eng Iowa State University Digital Repository https://lib.dr.iastate.edu/rtd/766 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1765&context=rtd Retrospective Theses and Dissertations Chemistry Physical chemistry Analytical Chemistry text 2004 ftiowastateuniv 2018-11-26T03:01:43Z This dissertation focuses on the applicability of a variety of time-resolved spectroscopic techniques to probe the excited state photophysics of a range of biologically and environmentally relevant systems.;Hypericin, a biologically active perylene quinone and an efficient photosensitizing agent has a wide spectrum of light induced biological activities. However, it is highly insoluble in water. Insertion of hypericin in the well-characterized AOT reverse micelles gives us the opportunity to study its excited-state photophysics as a function of varying pH. Hypomycin B, another biologically active perylene quinone is unique in the sense that it has only one hydroxyl group peri to a carbonyl group as opposed to four in hypericin. Transient absorption data failed to reveal any stimulated emission for hypomycin B. This result has been discussed in the context of the number of H-atoms that may be transferred in the excited state for hypericin and whether the transfer is stepwise or concerted.;Geminate recombination of ligands in heme proteins is mainly affected either by the proximal pocket effects or by mutations on the distal side of the heme pocket. Our transient absorption kinetics of different proximal mutants of both sperm whale myoglobin (Mb) and soybean leghemoglobin (Lba) reveal very little influence of the proximal pocket on the geminate recombination of NO. However, the first ever study of distal pocket mutations in Lba, show profound effects of the distal amino acid(s) on NO recombination on the geminate timescale.;Solvation dynamics of five different room temperature ionic liquids using coumarin 153 as the fluorescent probe reveal an initial phase of rapid solvation due to the polarizability of the cationic part of the ionic liquids. The amplitude of the rapidly decaying components correlates well with the viscosity of the ionic liquids. Finally, the complex of coumarin 153 with apomyoglobin has been exhaustively characterized. This is the first step towards analyzing the contribution of the individual amino acid residues in the heme pocket towards the total protein dielectric response. Text Sperm whale Digital Repository @ Iowa State University |
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Digital Repository @ Iowa State University |
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Chemistry Physical chemistry Analytical Chemistry Chowdhury, Pramit Kumar Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems |
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Chemistry Physical chemistry Analytical Chemistry |
description |
This dissertation focuses on the applicability of a variety of time-resolved spectroscopic techniques to probe the excited state photophysics of a range of biologically and environmentally relevant systems.;Hypericin, a biologically active perylene quinone and an efficient photosensitizing agent has a wide spectrum of light induced biological activities. However, it is highly insoluble in water. Insertion of hypericin in the well-characterized AOT reverse micelles gives us the opportunity to study its excited-state photophysics as a function of varying pH. Hypomycin B, another biologically active perylene quinone is unique in the sense that it has only one hydroxyl group peri to a carbonyl group as opposed to four in hypericin. Transient absorption data failed to reveal any stimulated emission for hypomycin B. This result has been discussed in the context of the number of H-atoms that may be transferred in the excited state for hypericin and whether the transfer is stepwise or concerted.;Geminate recombination of ligands in heme proteins is mainly affected either by the proximal pocket effects or by mutations on the distal side of the heme pocket. Our transient absorption kinetics of different proximal mutants of both sperm whale myoglobin (Mb) and soybean leghemoglobin (Lba) reveal very little influence of the proximal pocket on the geminate recombination of NO. However, the first ever study of distal pocket mutations in Lba, show profound effects of the distal amino acid(s) on NO recombination on the geminate timescale.;Solvation dynamics of five different room temperature ionic liquids using coumarin 153 as the fluorescent probe reveal an initial phase of rapid solvation due to the polarizability of the cationic part of the ionic liquids. The amplitude of the rapidly decaying components correlates well with the viscosity of the ionic liquids. Finally, the complex of coumarin 153 with apomyoglobin has been exhaustively characterized. This is the first step towards analyzing the contribution of the individual amino acid residues in the heme pocket towards the total protein dielectric response. |
format |
Text |
author |
Chowdhury, Pramit Kumar |
author_facet |
Chowdhury, Pramit Kumar |
author_sort |
Chowdhury, Pramit Kumar |
title |
Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems |
title_short |
Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems |
title_full |
Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems |
title_fullStr |
Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems |
title_full_unstemmed |
Picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems |
title_sort |
picosecond time resolved spectroscopy used as a tool to probe excited state photophysics of biologically and environmentally relevant systems |
publisher |
Iowa State University Digital Repository |
publishDate |
2004 |
url |
https://lib.dr.iastate.edu/rtd/766 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1765&context=rtd |
genre |
Sperm whale |
genre_facet |
Sperm whale |
op_source |
Retrospective Theses and Dissertations |
op_relation |
https://lib.dr.iastate.edu/rtd/766 https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1765&context=rtd |
_version_ |
1766208862531092480 |