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The influence of temperature on C153 steady-state absorption and fluorescence kinetics in hydrogen bonding solvents.

Dobek K, Karolczak J - J Fluoresc (2012)

Bottom Line: It leads to a modulation of the fluorescence transition dipole moment and it is the primary source of the experimental effects observed.Additionally, we have found that proticity of the solvent induces a rise in the fluorescence transition dipole moment, which leads to a shortening of the fluorescence lifetime.We show that while such bonds do not affect the transition probability, they do change the S(0) an S(1) energy gap which in turn implies a change in non-radiative transition rate in a similar way as in protic solvents, as well as in the fluorescence spectrum position.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Physics, Adam Mickiewicz University, Poznań, Poland. dobas@amu.edu.pl

ABSTRACT
In a recent paper (J Fluoresc (2011) 21:1547-1557) a temperature induced modulation of Coumarin 153 (C153) fluorescence lifetime and quantum yield for the probe dissolved in the polar, nonspecifically interacting 1-chloropropane was reported. This modulation was also observed in temperature dependencies of the radiative and nonradiative rates. Here, we show that the modulation is also observed in another 1-chloroalkane-1-chlorohexane, as well as in hydrogen bonding propionitrile, ethanol and trifluoroethanol. Change in the equilibrium distance between S (0) an S (1) potential energies surfaces was identified as the source of this modulation. This change is driven by temperature changes. It leads to a modulation of the fluorescence transition dipole moment and it is the primary source of the experimental effects observed. Additionally, we have found that proticity of the solvent induces a rise in the fluorescence transition dipole moment, which leads to a shortening of the fluorescence lifetime. Hydrogen bonds are formed by C153 also with hydrogen accepting solvents like propionitrile. We show that while such bonds do not affect the transition probability, they do change the S(0) an S(1) energy gap which in turn implies a change in non-radiative transition rate in a similar way as in protic solvents, as well as in the fluorescence spectrum position. Finally, the influence of temperature on the energies of hydrogen bonds formed by C153 when acting as hydrogen donor or acceptor is reported.

No MeSH data available.


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Temperature dependencies of the fluorescence decay time for C153 in ClH (a), PPN (b), EtOH (c) and TFEtOH (d). In the alcohols the dominant long component time (filled circles) of the double-exponential decay function fitted to the experimental decays is presented along with the single exponential decay time for TFEtOH (empty circles)
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Fig5: Temperature dependencies of the fluorescence decay time for C153 in ClH (a), PPN (b), EtOH (c) and TFEtOH (d). In the alcohols the dominant long component time (filled circles) of the double-exponential decay function fitted to the experimental decays is presented along with the single exponential decay time for TFEtOH (empty circles)

Mentions: First of all, fluorescence decays were measured for C153 in all solvents in the same temperature ranges as in the case of steady-state absorption and emission spectra. Due to some limitation of our experimental setup, during the experiment the excitation wavelength was constant and set to the maximum of the room temperature absorption spectrum in a selected solvent, while the emission wavelength was set to the maximum of the emission spectrum at a selected temperature. In ClH and PPN the decay was found to be properly described by a single exponential decay function in the full temperature range. In EtOH below 293 K and in TFEtOH in the full T range a double exponential fit was necessary to correctly reconstruct the data. The double exponential function consisted of a dominant long component. A decrease in temperature induced a change in the second component decay time from 100 ps (contribution F = 0.2 %) to 2,200 ps (F = 25 %) in EtOH, and from 100 ps (F = 0.6 %) to 900 ps (F = 4 %) in TFEtOH. The long component decay time had been found in both protic solvents to follow a similar temperature dependence as the single exponential decay time, also fitted to the data. Therefore, Fig. 5 shows τF of the single exponential fit for ClH, PPN and the long component of the double exponential fit for both protic solvents.Fig. 5


The influence of temperature on C153 steady-state absorption and fluorescence kinetics in hydrogen bonding solvents.

Dobek K, Karolczak J - J Fluoresc (2012)

Temperature dependencies of the fluorescence decay time for C153 in ClH (a), PPN (b), EtOH (c) and TFEtOH (d). In the alcohols the dominant long component time (filled circles) of the double-exponential decay function fitted to the experimental decays is presented along with the single exponential decay time for TFEtOH (empty circles)
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3473193&req=5

Fig5: Temperature dependencies of the fluorescence decay time for C153 in ClH (a), PPN (b), EtOH (c) and TFEtOH (d). In the alcohols the dominant long component time (filled circles) of the double-exponential decay function fitted to the experimental decays is presented along with the single exponential decay time for TFEtOH (empty circles)
Mentions: First of all, fluorescence decays were measured for C153 in all solvents in the same temperature ranges as in the case of steady-state absorption and emission spectra. Due to some limitation of our experimental setup, during the experiment the excitation wavelength was constant and set to the maximum of the room temperature absorption spectrum in a selected solvent, while the emission wavelength was set to the maximum of the emission spectrum at a selected temperature. In ClH and PPN the decay was found to be properly described by a single exponential decay function in the full temperature range. In EtOH below 293 K and in TFEtOH in the full T range a double exponential fit was necessary to correctly reconstruct the data. The double exponential function consisted of a dominant long component. A decrease in temperature induced a change in the second component decay time from 100 ps (contribution F = 0.2 %) to 2,200 ps (F = 25 %) in EtOH, and from 100 ps (F = 0.6 %) to 900 ps (F = 4 %) in TFEtOH. The long component decay time had been found in both protic solvents to follow a similar temperature dependence as the single exponential decay time, also fitted to the data. Therefore, Fig. 5 shows τF of the single exponential fit for ClH, PPN and the long component of the double exponential fit for both protic solvents.Fig. 5

Bottom Line: It leads to a modulation of the fluorescence transition dipole moment and it is the primary source of the experimental effects observed.Additionally, we have found that proticity of the solvent induces a rise in the fluorescence transition dipole moment, which leads to a shortening of the fluorescence lifetime.We show that while such bonds do not affect the transition probability, they do change the S(0) an S(1) energy gap which in turn implies a change in non-radiative transition rate in a similar way as in protic solvents, as well as in the fluorescence spectrum position.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Physics, Adam Mickiewicz University, Poznań, Poland. dobas@amu.edu.pl

ABSTRACT
In a recent paper (J Fluoresc (2011) 21:1547-1557) a temperature induced modulation of Coumarin 153 (C153) fluorescence lifetime and quantum yield for the probe dissolved in the polar, nonspecifically interacting 1-chloropropane was reported. This modulation was also observed in temperature dependencies of the radiative and nonradiative rates. Here, we show that the modulation is also observed in another 1-chloroalkane-1-chlorohexane, as well as in hydrogen bonding propionitrile, ethanol and trifluoroethanol. Change in the equilibrium distance between S (0) an S (1) potential energies surfaces was identified as the source of this modulation. This change is driven by temperature changes. It leads to a modulation of the fluorescence transition dipole moment and it is the primary source of the experimental effects observed. Additionally, we have found that proticity of the solvent induces a rise in the fluorescence transition dipole moment, which leads to a shortening of the fluorescence lifetime. Hydrogen bonds are formed by C153 also with hydrogen accepting solvents like propionitrile. We show that while such bonds do not affect the transition probability, they do change the S(0) an S(1) energy gap which in turn implies a change in non-radiative transition rate in a similar way as in protic solvents, as well as in the fluorescence spectrum position. Finally, the influence of temperature on the energies of hydrogen bonds formed by C153 when acting as hydrogen donor or acceptor is reported.

No MeSH data available.


Related in: MedlinePlus