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Counterion Migration Driven by Light-Induced Intramolecular Charge Transfer
[Image: see text] A series of D−π–A(+) pyridinium compounds, in which D = −NPh(2) and A(+) = −PyMe(+) are linked by various amounts of linear phenyl spacers, were strategically designed and synthesized. Their characterization revealed the presence of excited-state intramolecular charge transfer (ESI...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
American Chemical Society
2021
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8395631/ https://www.ncbi.nlm.nih.gov/pubmed/34467293 http://dx.doi.org/10.1021/jacsau.0c00107 |
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author | Lin, Ta-Chun Liu, Zong-Ying Liu, Shih-Hung Koshevoy, Igor O. Chou, Pi-Tai |
author_facet | Lin, Ta-Chun Liu, Zong-Ying Liu, Shih-Hung Koshevoy, Igor O. Chou, Pi-Tai |
author_sort | Lin, Ta-Chun |
collection | PubMed |
description | [Image: see text] A series of D−π–A(+) pyridinium compounds, in which D = −NPh(2) and A(+) = −PyMe(+) are linked by various amounts of linear phenyl spacers, were strategically designed and synthesized. Their characterization revealed the presence of excited-state intramolecular charge transfer (ESICT) that triggers a corresponding response from the counterion. In medium and strong polar solvents, the fast solvent relaxation occurring after ESICT overwhelms the counterion effect, showing typical emission solvatochromism. In weakly polar solvents, ESICT induces counteranion migration for electrostatic stabilization, the time scale of which is dependent on the radius of the counteranion, the length of the π-linker, and the viscosity of the solvent. In low-viscosity organic solvents such as toluene, counteranion migration occurs within several tens to hundreds of picoseconds, resulting in a time-dependent continuous emission that can be resolved from the spectral temporal evolution. Concrete evidence for this is provided by the chemical synthesis of a D−π–A(+) pyridinium–sulfur trioxide(–) zwitterion, where anion migration is restricted due to its internally locked ion pair. As a result, only a single emission band can be observed. These comprehensive studies prove that the ion migration process may be significant for a wide range of ESICT-type ionic fluorophores. Such an ionic movement, triggered by optically pumped ESICT of the D−π–A(+) dyad, is similar to the molecular machine driven by the redox reaction, but with a facile access and fast response. |
format | Online Article Text |
id | pubmed-8395631 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2021 |
publisher | American Chemical Society |
record_format | MEDLINE/PubMed |
spelling | pubmed-83956312021-08-30 Counterion Migration Driven by Light-Induced Intramolecular Charge Transfer Lin, Ta-Chun Liu, Zong-Ying Liu, Shih-Hung Koshevoy, Igor O. Chou, Pi-Tai JACS Au [Image: see text] A series of D−π–A(+) pyridinium compounds, in which D = −NPh(2) and A(+) = −PyMe(+) are linked by various amounts of linear phenyl spacers, were strategically designed and synthesized. Their characterization revealed the presence of excited-state intramolecular charge transfer (ESICT) that triggers a corresponding response from the counterion. In medium and strong polar solvents, the fast solvent relaxation occurring after ESICT overwhelms the counterion effect, showing typical emission solvatochromism. In weakly polar solvents, ESICT induces counteranion migration for electrostatic stabilization, the time scale of which is dependent on the radius of the counteranion, the length of the π-linker, and the viscosity of the solvent. In low-viscosity organic solvents such as toluene, counteranion migration occurs within several tens to hundreds of picoseconds, resulting in a time-dependent continuous emission that can be resolved from the spectral temporal evolution. Concrete evidence for this is provided by the chemical synthesis of a D−π–A(+) pyridinium–sulfur trioxide(–) zwitterion, where anion migration is restricted due to its internally locked ion pair. As a result, only a single emission band can be observed. These comprehensive studies prove that the ion migration process may be significant for a wide range of ESICT-type ionic fluorophores. Such an ionic movement, triggered by optically pumped ESICT of the D−π–A(+) dyad, is similar to the molecular machine driven by the redox reaction, but with a facile access and fast response. American Chemical Society 2021-01-25 /pmc/articles/PMC8395631/ /pubmed/34467293 http://dx.doi.org/10.1021/jacsau.0c00107 Text en © 2021 The Authors. Published by American Chemical Society https://pubs.acs.org/page/policy/authorchoice_ccbyncnd_termsofuse.htmlThis is an open access article published under a Creative Commons Non-Commercial No Derivative Works (CC-BY-NC-ND) Attribution License (https://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 | Lin, Ta-Chun Liu, Zong-Ying Liu, Shih-Hung Koshevoy, Igor O. Chou, Pi-Tai Counterion Migration Driven by Light-Induced Intramolecular Charge Transfer |
title | Counterion Migration Driven by Light-Induced Intramolecular
Charge Transfer |
title_full | Counterion Migration Driven by Light-Induced Intramolecular
Charge Transfer |
title_fullStr | Counterion Migration Driven by Light-Induced Intramolecular
Charge Transfer |
title_full_unstemmed | Counterion Migration Driven by Light-Induced Intramolecular
Charge Transfer |
title_short | Counterion Migration Driven by Light-Induced Intramolecular
Charge Transfer |
title_sort | counterion migration driven by light-induced intramolecular
charge transfer |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8395631/ https://www.ncbi.nlm.nih.gov/pubmed/34467293 http://dx.doi.org/10.1021/jacsau.0c00107 |
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