Investigating the influence of substituent groups in TTM based radicals for the excitation process: a theoretical study
Tri-(2,4,6-trichlorophenyl)methyl (TTM) based radicals can be promising in providing relatively high fluorescence quantum efficiency. In this study, we have evaluated the photoluminescence properties of a series of TTM-based radicals by means of DFT and TD-DFT methods. The optimized structures of th...
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Veröffentlicht in: | Physical chemistry chemical physics : PCCP 2023-09, Vol.25 (37), p.25871-25879 |
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Sprache: | eng |
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Zusammenfassung: | Tri-(2,4,6-trichlorophenyl)methyl (TTM) based radicals can be promising in providing relatively high fluorescence quantum efficiency. In this study, we have evaluated the photoluminescence properties of a series of TTM-based radicals by means of DFT and TD-DFT methods. The optimized structures of the ground states (D
0
) and the first excited states (D
1
) of all the radicals are calculated and the computed emission bands are comparable with previous experimental results.
k
nr
is determined from transition dipole moments (
12
) and the energy gaps between D
0
and D
1
(
E
), both of which can be regulated by the conjugated structures from the substituent groups.
k
nr
was derived from the mode-averaging method and is consistent with the experimental results. Factors influencing
k
r
and
k
nr
, including the potential energy differences (
G
0
), the vibrational reorganization energies (
) and the electron coupling term (
H
ab
), are discussed. By comparing
k
r
and
k
nr
in solvents with different polarities (cyclohexane, toluene, and chloroform), TTM based radicals in cyclohexane exhibit the most promising fluorescence efficiencies. Besides, two substituted radicals, namely 2Br-TTM-3PCz and 2F-TTM-3PCz, have been fabricated. The results show that fluorine atoms are able to increase
G
0
and a considerably small
k
nr
has been predicted. We expect that our calculation can benefit the design of light-emitting molecules in further experiments.
The mode-average method was employed to compute the
k
nr
for several TTM-based radicals. The conjugated structures and the polarity of solvents can influence
k
r
and
k
nr
. The fluorine substituted trichlorophenyl group can lead to a decrease of
k
nr
. |
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ISSN: | 1463-9076 1463-9084 |
DOI: | 10.1039/d3cp01248d |