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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.


Related in: MedlinePlus

Temperature dependence of fluorescence decay time of C153 in dehydrated ClH (a)–filled circles, in ClH+water mixture at 2.2⋅10−3 M water concentration (a)–empty circles, in dehydrated PPN (b)–filled circles and in improperly dehydrated PPN (b)–empty circles
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Fig6: Temperature dependence of fluorescence decay time of C153 in dehydrated ClH (a)–filled circles, in ClH+water mixture at 2.2⋅10−3 M water concentration (a)–empty circles, in dehydrated PPN (b)–filled circles and in improperly dehydrated PPN (b)–empty circles

Mentions: Effects of improper dehydration of 1-chloroalkanes on 4-AP thermochromism were reported in Ref. [12]. For C153 in ClP and ClH we also noticed that incorrect dehydration of these solvents led to the τF(T) dependencies significantly different from that shown in Fig. 5 and in Ref. [7]. A similar observation was also made for C153 in PPN. Thus, following the procedure undertaken in Ref. [12] we had preliminarily dehydrated 50 mL of ClH and next we added to it 2 μL of distilled water, which corresponded to a 2.2⋅10−3 M water concentration. Fluorescence decays in such a ClH+water mixture were measured at the wavelengths corresponding to the maxima of steady-state spectra collected at subsequent temperatures. They were found to be described by double exponential decay functions with a dominant 5–6 ns component and a minor ~200 ps second component whose contribution did not exceed 1 %. Figure 6a presents the temperature dependence of the long component for C153 dissolved in ClH+water mixture along with the dependence found in dehydrated ClH shown already in Fig. 5. Additionally, Fig. 6b shows the impact of improper dehydration of PPN on C153 τF(T) dependence. The properly dehydrated sample (filled circles) was prepared with PPN dried with molecular sieves twice as long as for the improperly dehydrated one (empty circles), after changing the molecular sieves once. It was also prepared under argon atmosphere in contrast to the sample still contaminated by water.Fig. 6


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

Dobek K, Karolczak J - J Fluoresc (2012)

Temperature dependence of fluorescence decay time of C153 in dehydrated ClH (a)–filled circles, in ClH+water mixture at 2.2⋅10−3 M water concentration (a)–empty circles, in dehydrated PPN (b)–filled circles and in improperly dehydrated PPN (b)–empty circles
© Copyright Policy
Related In: Results  -  Collection

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

Fig6: Temperature dependence of fluorescence decay time of C153 in dehydrated ClH (a)–filled circles, in ClH+water mixture at 2.2⋅10−3 M water concentration (a)–empty circles, in dehydrated PPN (b)–filled circles and in improperly dehydrated PPN (b)–empty circles
Mentions: Effects of improper dehydration of 1-chloroalkanes on 4-AP thermochromism were reported in Ref. [12]. For C153 in ClP and ClH we also noticed that incorrect dehydration of these solvents led to the τF(T) dependencies significantly different from that shown in Fig. 5 and in Ref. [7]. A similar observation was also made for C153 in PPN. Thus, following the procedure undertaken in Ref. [12] we had preliminarily dehydrated 50 mL of ClH and next we added to it 2 μL of distilled water, which corresponded to a 2.2⋅10−3 M water concentration. Fluorescence decays in such a ClH+water mixture were measured at the wavelengths corresponding to the maxima of steady-state spectra collected at subsequent temperatures. They were found to be described by double exponential decay functions with a dominant 5–6 ns component and a minor ~200 ps second component whose contribution did not exceed 1 %. Figure 6a presents the temperature dependence of the long component for C153 dissolved in ClH+water mixture along with the dependence found in dehydrated ClH shown already in Fig. 5. Additionally, Fig. 6b shows the impact of improper dehydration of PPN on C153 τF(T) dependence. The properly dehydrated sample (filled circles) was prepared with PPN dried with molecular sieves twice as long as for the improperly dehydrated one (empty circles), after changing the molecular sieves once. It was also prepared under argon atmosphere in contrast to the sample still contaminated by water.Fig. 6

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