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SINGLET OXYGEN GENERATION USING NEW FLUORENE-BASED PHOTOSENSITIZERS UNDER ONE- AND TWO-PHOTON EXCITATION

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Date Issued:
2007
Abstract/Description:
Molecular oxygen in its lowest electronically excited state plays an important roll in the field of chemistry. This excited state is often referred to as singlet oxygen and can be generated in a photosensitized process under one- or two-photon excitation of a photosensitizer. It is particularly useful in the field of photodynamic cancer therapy (PDT) where singlet oxygen formation can be used to destroy cancerous tumors. The use of two-photon activated photosensitizers possesses great potential in the field of PDT since near-IR light is used to activate the sensitizer, resulting in deeper penetration of light into biological tissue, less photo-bleaching of the sensitizer, and greatly improved resolution of excitation. The synthesis and photophysical characterization of new fluorene-based photosensitizers for efficient singlet oxygen production were investigated. The spectral properties for singlet oxygen production were measured at room temperature and 77 K. Two-photon absorption (2PA) cross-sections of the fluorene derivatives were measured by the open aperture Z-scan method. The quantum yields of singlet oxygen generation under one- and two-photon excitation (ΦΔ and 2PAΦΔ, respectively) were determined by the direct measurement of singlet oxygen luminescence at ≈ 1270 nm. The values of ΦΔ were independent of excitation wavelength, ranging from 0.6 - 0.9. The singlet oxygen quantum yields under two-photon excitation were 2PAΦΔ ≈ ½ΦΔ, indicating that the two processes exhibited the same mechanism of singlet oxygen production, independent of the mechanism of photon absorption.
Title: SINGLET OXYGEN GENERATION USING NEW FLUORENE-BASED PHOTOSENSITIZERS UNDER ONE- AND TWO-PHOTON EXCITATION.
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Name(s): Andrasik, Stephen, Author
Belfield, Kevin, Committee Chair
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2007
Publisher: University of Central Florida
Language(s): English
Abstract/Description: Molecular oxygen in its lowest electronically excited state plays an important roll in the field of chemistry. This excited state is often referred to as singlet oxygen and can be generated in a photosensitized process under one- or two-photon excitation of a photosensitizer. It is particularly useful in the field of photodynamic cancer therapy (PDT) where singlet oxygen formation can be used to destroy cancerous tumors. The use of two-photon activated photosensitizers possesses great potential in the field of PDT since near-IR light is used to activate the sensitizer, resulting in deeper penetration of light into biological tissue, less photo-bleaching of the sensitizer, and greatly improved resolution of excitation. The synthesis and photophysical characterization of new fluorene-based photosensitizers for efficient singlet oxygen production were investigated. The spectral properties for singlet oxygen production were measured at room temperature and 77 K. Two-photon absorption (2PA) cross-sections of the fluorene derivatives were measured by the open aperture Z-scan method. The quantum yields of singlet oxygen generation under one- and two-photon excitation (ΦΔ and 2PAΦΔ, respectively) were determined by the direct measurement of singlet oxygen luminescence at ≈ 1270 nm. The values of ΦΔ were independent of excitation wavelength, ranging from 0.6 - 0.9. The singlet oxygen quantum yields under two-photon excitation were 2PAΦΔ ≈ ½ΦΔ, indicating that the two processes exhibited the same mechanism of singlet oxygen production, independent of the mechanism of photon absorption.
Identifier: CFE0001860 (IID), ucf:47411 (fedora)
Note(s): 2007-12-01
Ph.D.
Sciences, Department of Chemistry
Doctorate
This record was generated from author submitted information.
Subject(s): Singlet oxygen
Luminescence
Two-photon absorption
Photochemistry
Photosensitization
Photodynamic therapy
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFE0001860
Restrictions on Access: campus 2008-12-04
Host Institution: UCF

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