Please use this identifier to cite or link to this item:
https://hdl.handle.net/10316/10640
Title: | Dramatic Pressure-Dependent Quenching Effects in Supercritical CO2 Assessed by the Fluorescence of 4‘-Dimethylamino-3-hydroxyflavone. Thermodynamic versus Kinetics Control of Excited-State Intramolecular Proton Transfer | Authors: | Barroso, Mónica Chattopadhyay, Nitin Klymchenko, Andrey S. Demchenko, Alexander P. Arnaut, Luís G. Formosinho, Sebastião J. |
Issue Date: | 21-Dec-2006 | Publisher: | American Chemical Society | Citation: | The Journal of Physical Chemistry A. 110:50 (2006) 13419-13424 | Abstract: | Steady-state fluorescence of 4‘-dimethylamino-3-hydroxyflavone (DMA3HF) was observed in supercritical carbon dioxide (scCO2). Excited-state intramolecular proton transfer (ESIPT) occurs resulting in two well-separated emission bands corresponding to the normal and tautomer forms. As the scCO2 density exceeds 0.7 g/mL, the relative intensity of the two bands tends to a constant value, comparable to that observed for organic solvents with ET(30) = 33.0 ± 0.5 kcal/mol, such as toluene and di-n-butyl ether. At lower densities, the substantial decrease of the total fluorescence intensity (a 600-fold decrease as the pressure decreases from 100 to 80 bar) is accompanied by an even more accentuated decrease of the tautomer fluorescence. This can be explained by a shift in the equilibrium between normal and tautomer forms, concomitant with a more efficient quenching of the less solvated fluorophore, that may change the thermodynamic control of the relative population of the two emissive species to a kinetic control. | URI: | https://hdl.handle.net/10316/10640 | ISSN: | 1089-5639 | DOI: | 10.1021/jp0643606 | Rights: | openAccess |
Appears in Collections: | FCTUC Química - Artigos em Revistas Internacionais |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
Dramatic Pressure-Dependent Quenching Effects in Supercritical.pdf | 99.5 kB | Adobe PDF | View/Open |
SCOPUSTM
Citations
16
checked on May 1, 2023
WEB OF SCIENCETM
Citations
5
17
checked on Aug 2, 2024
Page view(s) 50
480
checked on Sep 24, 2024
Download(s) 50
465
checked on Sep 24, 2024
Google ScholarTM
Check
Altmetric
Altmetric
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.