Ruiqi Wu, Yanliang Zhao, Ye Gao, Aihua Gao, Yanli Liu, Li Wang, Meishan Wang
{"title":"Theoretical study of excited state dynamics of a ratiometric fluorescent probe for detection of SO<sub>2</sub> derivatives.","authors":"Ruiqi Wu, Yanliang Zhao, Ye Gao, Aihua Gao, Yanli Liu, Li Wang, Meishan Wang","doi":"10.1016/j.saa.2024.125165","DOIUrl":null,"url":null,"abstract":"<p><p>Sulfur dioxide (SO<sub>2</sub>), a toxic air pollutant, can have harmful effects on human health when inhaled or when it forms bisulfite in the body. In the present work, a ratiometric fluorescent probe, 2-(2'-hydroxyphenyl)benzothiazole-3-ethyl-1,1,2-trimethyl-1H-benzo[e]indolium (HBT-EMBI), was selected to study the mechanism of SO<sub>2</sub> derivatives detection. This study provides insights into the attributions of ratiometric fluorescence through hydrogen bond dynamics, electronic excitation properties, radiation rates, and excited state intramolecular proton transfer (ESIPT) processes using the density functional theory (DFT) and the time-dependent density functional theory (TDDFT) level. The results confirm that the large Stokes shifts and broad emission spectra of the HBT-EMBI probe are associated with its intramolecular charge transfer (ICT) characteristics and hydrogen bonding-driven ESIPT processes, respectively. After the addition reaction between the probe and HSO<sub>3</sub><sup>-</sup>/SO<sub>3</sub><sup>2-</sup>, the conformational populations of HBT-EMBI-HSO<sub>3</sub><sup>-</sup> transfer abnormally from enol configurations to more stable keto configurations, which leads to a distinguished change in the visible color and the ratiometric fluorescence signal, and is not due to the blockage of the ICT process of HBT-EMBI-HSO<sub>3</sub><sup>-</sup>, as previously reported. This work provides a new perspective on the mechanism of detection of SO<sub>2</sub> derivatives by ESIPT fluorescent probes.</p>","PeriodicalId":94213,"journal":{"name":"Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1016/j.saa.2024.125165","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/9/20 0:00:00","PubModel":"Epub","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Sulfur dioxide (SO2), a toxic air pollutant, can have harmful effects on human health when inhaled or when it forms bisulfite in the body. In the present work, a ratiometric fluorescent probe, 2-(2'-hydroxyphenyl)benzothiazole-3-ethyl-1,1,2-trimethyl-1H-benzo[e]indolium (HBT-EMBI), was selected to study the mechanism of SO2 derivatives detection. This study provides insights into the attributions of ratiometric fluorescence through hydrogen bond dynamics, electronic excitation properties, radiation rates, and excited state intramolecular proton transfer (ESIPT) processes using the density functional theory (DFT) and the time-dependent density functional theory (TDDFT) level. The results confirm that the large Stokes shifts and broad emission spectra of the HBT-EMBI probe are associated with its intramolecular charge transfer (ICT) characteristics and hydrogen bonding-driven ESIPT processes, respectively. After the addition reaction between the probe and HSO3-/SO32-, the conformational populations of HBT-EMBI-HSO3- transfer abnormally from enol configurations to more stable keto configurations, which leads to a distinguished change in the visible color and the ratiometric fluorescence signal, and is not due to the blockage of the ICT process of HBT-EMBI-HSO3-, as previously reported. This work provides a new perspective on the mechanism of detection of SO2 derivatives by ESIPT fluorescent probes.