Determination of excited state dipole moments in solution via thermochromic methods

Mirko Matthias Lindic,Matthias Zajonz,Marie-Luise Hebestreit,Michael Schneider,W Leo Meerts,Michael Schmitt

doi:10.1016/j.mex.2020.101101

Mirko Matthias Lindic, Matthias Zajonz + Show 4 more

Open Access

https://doi.org/10.1016/j.mex.2020.101101

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Abstract

The method basically combines the existing ideas of excited state dipole moment determination via thermochromic fluorescence spectroscopy with the determination of the solvent cavity volume via concentration dependent density measurements of the solution densities at different weight fractions. Additionally, the determination of the cavity volume in dependence of the solvent temperature is included here, which provides a better accuracy of the excited state dipole moment determination. With this step two major sources of errors are eliminated: the use of the very imprecise Onsager radius and the assumption, that the cavity size is temperature independent.•Thermochromic absorption and fluorescence spectroscopy.•Cavity volume determination by density measurements.•Temperature dependent cavity volume determination.

Highlights

The determination of excited state dipole moments using solvatochromic shifts of absorption/emission spectra in different solvents has many shortcomings, that are well-documented [1,2,3,4,5], it is still widely applied experimentally [6,7,8,9] and investigated theoretically [10], due to its conceptual and experimental simplicity
The determination of the cavity volume in dependence of the solvent temperature is included here, which provides a better accuracy of the excited state dipole moment determination
Some of the problems that are connected with the solvatochromic method can be solved, if one makes use of the fact, that variation of the solvent polarity function might as well be reached by variation of the temperature of the solution in spite of the solvent

Summary

Introduction

The determination of excited state dipole moments using solvatochromic shifts of absorption/emission spectra in different solvents has many shortcomings, that are well-documented [1,2,3,4,5], it is still widely applied experimentally [6,7,8,9] and investigated theoretically [10], due to its conceptual and experimental simplicity. Determination of excited state dipole moments in solution via thermochromic methods Mirko Matthias Lindic a, Matthias Zajonz a, Marie-Luise Hebestreit a, Michael Schneider a, W. The determination of the cavity volume in dependence of the solvent temperature is included here, which provides a better accuracy of the excited state dipole moment determination.

Results

Conclusion