Document Detail


Intrinsic and extrinsic temperature-dependency of viscosity-sensitive fluorescent molecular rotors.
MedLine Citation:
PMID:  21947609     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Molecular rotors are a group of environment-sensitive fluorescent probes whose quantum yield depends on the ability to form twisted intramolecular charge-transfer (TICT) states. TICT formation is dominantly governed by the solvent's microviscosity, but polarity and the ability of the solvent to form hydrogen bonds play an additional role. The relationship between quantum yield ϕ(F) and viscosity η is widely accepted as a power-law, ϕ(F) = C · η(x). In this study, we isolated the direct influence of the temperature on the TICT formation rate by examining several molecular rotors in protic and aprotic solvents over a range of temperatures. Each solvent's viscosity was determined as a function of temperature and used in the above power-law to determine how the proportionality constant C varies with temperature. We found that the power-law relationship fully explains the variations of the measured steady-state intensity by temperature-induced variations of the solvent viscosity, and C can be assumed to be temperature-independent. The exponent x, however, was found to be significantly higher in aprotic solvents than in protic solvents. We conclude that the ability of the solvent to form hydrogen bonds has a major influence on the relationship between viscosity and quantum yield. To use molecular rotors for the quantitative determination of viscosity or microviscosity, the exponent x needs to be determined for each dye-solvent combination.
Authors:
Sarah Howell; Marianna Dakanali; Emmanuel A Theodorakis; Mark A Haidekker
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2011-09-27
Journal Detail:
Title:  Journal of fluorescence     Volume:  22     ISSN:  1573-4994     ISO Abbreviation:  J Fluoresc     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-19     Completed Date:  2012-05-14     Revised Date:  2013-06-27    
Medline Journal Info:
Nlm Unique ID:  9201341     Medline TA:  J Fluoresc     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  457-65     Citation Subset:  IM    
Affiliation:
Faculty of Engineering, University of Georgia, 597 D.W. Brooks Drive, Athens, GA 30602, USA.
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MeSH Terms
Descriptor/Qualifier:
Fluorescent Dyes / chemistry*
Rotation*
Temperature*
Viscosity
Grant Support
ID/Acronym/Agency:
1R21 RR 025358/RR/NCRR NIH HHS; R21 RR025358/RR/NCRR NIH HHS; R21 RR025358-02/RR/NCRR NIH HHS
Chemical
Reg. No./Substance:
0/Fluorescent Dyes
Comments/Corrections

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