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Efficient Photooxidation of Sulfides with Amidated Alloxazines as Heavy-atom-free Photosensitizers
[Image: see text] Photooxidation utilizing visible light, especially with naturally abundant O(2) as the oxygen source, has been well-accepted as a sustainable and efficient procedure in organic synthesis. To ensure the intersystem crossing and triplet quantum yield for efficient photosensitization,...
Autores principales: | , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2020
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227068/ https://www.ncbi.nlm.nih.gov/pubmed/32426617 http://dx.doi.org/10.1021/acsomega.0c01087 |
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author | Guo, Huimin Xia, Hongyu Ma, Xiaolin Chen, Kepeng Dang, Can Zhao, Jianzhang Dick, Bernhard |
author_facet | Guo, Huimin Xia, Hongyu Ma, Xiaolin Chen, Kepeng Dang, Can Zhao, Jianzhang Dick, Bernhard |
author_sort | Guo, Huimin |
collection | PubMed |
description | [Image: see text] Photooxidation utilizing visible light, especially with naturally abundant O(2) as the oxygen source, has been well-accepted as a sustainable and efficient procedure in organic synthesis. To ensure the intersystem crossing and triplet quantum yield for efficient photosensitization, we prepared amidated alloxazines (AAs) and investigated their photophysical properties and performance as heavy-atom-free triplet photosensitizers and compared with those of flavin (FL) and riboflavin tetraacetate (RFTA). Because of the difference in the framework structure of AAs and FL and the introduction of carbonyl moiety, the absorption of FL at ∼450 nm is blue-shifted to ∼380 nm and weakened (ε = 8.7 × 10(3) for FL to ∼6.8 × 10(3) M(–1) cm(–1)), but the absorption at ∼340 nm is red-shifted to ∼350 nm and enhanced by ∼50% (from ε = 6.4 × 10(3) for FL to ∼9.9 × 10(3) M(–1) cm(–1)) in AAs. The intersystem crossing rates from the S(1) to T(1) are also enhanced in these AAs derivatives, while the fluorescence quantum yield decreases from ∼30 to ∼7% for FL and AAs, respectively, making the triplet excited state lifetime and the singlet oxygen quantum yield of AAs at least comparable to those of FL and RFTA. We examined the performance of these heave-atom-free chromophores in the photooxidation of sulfides to afford sulfoxides. In accordance with the prolonged triplet excited state lifetime and enhanced triplet quantum yield, 2–5-fold performance enhancements were observed for AAs in the photooxidation of sulfides with respect to FL. We proposed that the key reactive oxygen species of AA-sensitized photooxidation are singlet oxygen and superoxide radical anion based on mechanistic investigations. The research highlights the superior performance of AAs in photocatalysis and would be helpful to rationalize the design of efficient heavy-atom-free organic photocatalysts. |
format | Online Article Text |
id | pubmed-7227068 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-72270682020-05-18 Efficient Photooxidation of Sulfides with Amidated Alloxazines as Heavy-atom-free Photosensitizers Guo, Huimin Xia, Hongyu Ma, Xiaolin Chen, Kepeng Dang, Can Zhao, Jianzhang Dick, Bernhard ACS Omega [Image: see text] Photooxidation utilizing visible light, especially with naturally abundant O(2) as the oxygen source, has been well-accepted as a sustainable and efficient procedure in organic synthesis. To ensure the intersystem crossing and triplet quantum yield for efficient photosensitization, we prepared amidated alloxazines (AAs) and investigated their photophysical properties and performance as heavy-atom-free triplet photosensitizers and compared with those of flavin (FL) and riboflavin tetraacetate (RFTA). Because of the difference in the framework structure of AAs and FL and the introduction of carbonyl moiety, the absorption of FL at ∼450 nm is blue-shifted to ∼380 nm and weakened (ε = 8.7 × 10(3) for FL to ∼6.8 × 10(3) M(–1) cm(–1)), but the absorption at ∼340 nm is red-shifted to ∼350 nm and enhanced by ∼50% (from ε = 6.4 × 10(3) for FL to ∼9.9 × 10(3) M(–1) cm(–1)) in AAs. The intersystem crossing rates from the S(1) to T(1) are also enhanced in these AAs derivatives, while the fluorescence quantum yield decreases from ∼30 to ∼7% for FL and AAs, respectively, making the triplet excited state lifetime and the singlet oxygen quantum yield of AAs at least comparable to those of FL and RFTA. We examined the performance of these heave-atom-free chromophores in the photooxidation of sulfides to afford sulfoxides. In accordance with the prolonged triplet excited state lifetime and enhanced triplet quantum yield, 2–5-fold performance enhancements were observed for AAs in the photooxidation of sulfides with respect to FL. We proposed that the key reactive oxygen species of AA-sensitized photooxidation are singlet oxygen and superoxide radical anion based on mechanistic investigations. The research highlights the superior performance of AAs in photocatalysis and would be helpful to rationalize the design of efficient heavy-atom-free organic photocatalysts. American Chemical Society 2020-04-28 /pmc/articles/PMC7227068/ /pubmed/32426617 http://dx.doi.org/10.1021/acsomega.0c01087 Text en Copyright © 2020 American Chemical Society This is an open access article published under a Creative Commons Non-Commercial No Derivative Works (CC-BY-NC-ND) Attribution License (http://pubs.acs.org/page/policy/authorchoice_ccbyncnd_termsofuse.html) , which permits copying and redistribution of the article, and creation of adaptations, all for non-commercial purposes. |
spellingShingle | Guo, Huimin Xia, Hongyu Ma, Xiaolin Chen, Kepeng Dang, Can Zhao, Jianzhang Dick, Bernhard Efficient Photooxidation of Sulfides with Amidated Alloxazines as Heavy-atom-free Photosensitizers |
title | Efficient Photooxidation of Sulfides with Amidated
Alloxazines as Heavy-atom-free Photosensitizers |
title_full | Efficient Photooxidation of Sulfides with Amidated
Alloxazines as Heavy-atom-free Photosensitizers |
title_fullStr | Efficient Photooxidation of Sulfides with Amidated
Alloxazines as Heavy-atom-free Photosensitizers |
title_full_unstemmed | Efficient Photooxidation of Sulfides with Amidated
Alloxazines as Heavy-atom-free Photosensitizers |
title_short | Efficient Photooxidation of Sulfides with Amidated
Alloxazines as Heavy-atom-free Photosensitizers |
title_sort | efficient photooxidation of sulfides with amidated
alloxazines as heavy-atom-free photosensitizers |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7227068/ https://www.ncbi.nlm.nih.gov/pubmed/32426617 http://dx.doi.org/10.1021/acsomega.0c01087 |
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