Low-Lying Excited States of C120 and C151: A Multireference Perturbation Theory Study

Sakata, Tetsuya; Kawashima, Yukio; Nakano, Haruyuki

doi:10.1021/jp1019872

Cited by 12 publications

(11 citation statements)

References 58 publications

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“…Here, we restrict ourselves to the lowest excitations in the optical spectra because the experiments do not explore the region below 300 nm. Calculations exploring the <300‐nm region have been reported elsewhere for Coumarin 2 , showing the next transition with significant oscillator strength to be at 5.4 eV (208 nm).…”

Section: Resultssupporting

confidence: 56%

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Coumarins: Spectroscopic measurements and first principles calculations of C4‐substituted 7‐aminocoumarins

Singh

Begoyan

Tanasova

et al. 2018

J of Physical Organic Chem

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Coumarins are widely applied in sensing devices due to their diverse fluorescence properties. In this paper, we consider the C4-substituted 7aminocoumarins to investigate the structure-property relationship via examining the effect of the various substitutions on their optical properties. Absorption and fluorescence measurements together with time-dependent density functional theory calculations are described. We find that the significant red shift in the fluorescence spectra is associated with the cyclic carbonyl group of coumarins due to a substantial increase in the dipole moment in the photoexcited state. The apparent correlation between experimental and calculated results provides an atomistic-level insight into the role of the functionality at the C4 of coumarins and sets the basis for using computational analysis to predict the fluorescence properties of coumarins.

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Section: Resultssupporting

confidence: 56%

“…The theoretical findings were correlated to the experimental data produced with chemically obtained coumarin analogs. Although analysis of few members of this set has been previously investigated, this is a systematic experimental/theoretical study of a set of C4‐substituted 7‐aminocoumarin analogs.…”

Section: Introductionmentioning

confidence: 99%

Coumarins: Spectroscopic measurements and first principles calculations of C4‐substituted 7‐aminocoumarins

Singh

Begoyan

Tanasova

et al. 2018

J of Physical Organic Chem

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“…In the literature, the reported photophysical properties on the coumarin dyes, including that of C153 dye, in different organic solvents have been realized mainly from the observations made at the emission and absorption maxima of the dyes, suggesting that these dyes mainly exist as the monomeric species in the solution. − , On the basis of these reports, we infer that the longest lifetime component (τ 3 ) of about 4.8 ns, which dominates the decays for C153 dye in EtOH solution, is due to the monomeric species. , Accordingly, the two shorter lifetime components (τ 1 and τ 2 ) observed for the dye in EtOH solution are ascribed to the dye aggregates formed in the solution. From the observed decays in Figure B and Figure B it is very evident that the contributions of these aggregates (τ 1 and τ 2 ) are always comparatively higher at the shorter emission wavelengths, suggesting that the aggregate emissions are largely blue-shifted relative to the monomer emission.…”

Section: Resultsmentioning

confidence: 82%

“…In the literature, the reported photophysical properties on the coumarin dyes, including that of C153 dye, in different organic solvents have been realized mainly from the observations made at the emission and absorption maxima of the dyes, suggesting that these dyes mainly exist as the monomeric species in the solution. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]42 On the basis of these reports, we infer that the longest lifetime component (τ 3 ) of about 4.8 ns, which dominates the decays for C153 dye in EtOH solution, is due to the monomeric species. 29,42 Accordingly, the two shorter lifetime components (τ 1 and τ 2 ) observed for the dye in EtOH solution are ascribed to the dye aggregates formed in the solution.…”

Section: Construction Of Time-resolved Emission Spectramentioning

confidence: 77%

Aggregation Studies of Dipolar Coumarin-153 Dye in Polar Solvents: A Photophysical Study

Verma

Pal

2014

J. Phys. Chem. A

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Photophysical studies have been carried out to explore the aggregation behavior of coumarin-153 (C153) dye in polar organic solvents of both aprotic and protic nature, namely acetonitrile (ACN) and ethanol (EtOH). No unusual behavior is observed in aprotic ACN solvent, suggesting only the monomers of the dye as the single emitting species in the solution. In protic EtOH solvent, however, the dye shows the presence of multiple emitting species in the solution. The concentration-, temperature- and wavelength-dependent changes in the fluorescence decays, and the time-resolved emission spectra (TRES) and area-normalized emission spectra (TRANES) suggest the coexistence of dye aggregates along with the dye monomers in the EtOH solution. Observed results indicate that the emission spectra of the aggregates are substantially blue-shifted compared to the spectra of the monomers, suggesting the H-aggregation of the dye in the present cases. Time-resolved fluorescence anisotropy, ultrafast fluorescence up-conversion measurements and scanning electron microscopy studies support the aggregation of the dye in EtOH solution. Strong dipole-dipole interaction is supposedly responsible for the aggregation of C153 dye (dipole moment ∼6.4 D) and the polar protic solvent EtOH apparently stabilizes the aggregates through solute-solvent hydrogen bonding interaction, which is not possible in aprotic ACN solvent. This is further supported by the time-resolved fluorescence results in a strongly hydrogen bond donating solvent, 2,2,2-trifluoroethanol. Aggregation of C153 dye observed in the present study in polar protic organic solvent is an intriguing finding, as the dye is widely used as a fluorescent probe for various photochemical studies, where overlooking such aggregation will definitely mislead the observed results.

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“…We have succeeded in obtaining accurate excitation and fluorescence energies of coumarin 120 and 151 in a previous work of ours. 24 The electrons of the solvent molecules may play an important role in the excitation process, where they instantly respond to the change of the solute electronic structure. 25,67,68 In the previous work, 30 we investigated the effect of the solvent MM induced dipoles, which were introduced in the first QM/MM calculations, 25 on the absorption spectra.…”

Section: Introductionmentioning

confidence: 99%

Solvent effect on the absorption spectra of coumarin 120 in water: A combined quantum mechanical and molecular mechanical study

Sakata

Kawashima

Nakano

2011

The Journal of Chemical Physics

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The solvent effect on the absorption spectra of coumarin 120 (C120) in water was studied utilizing the combined quantum mechanical∕molecular mechanical (QM∕MM) method. In molecular dynamics (MD) simulation, a new sampling scheme was introduced to provide enough samples for both solute and solvent molecules to obtain the average physical properties of the molecules in solution. We sampled the structure of the solute and solvent molecules separately. First, we executed a QM∕MM MD simulation, where we sampled the solute molecule in solution. Next, we chose random solute structures from this simulation and performed classical MD simulation for each chosen solute structure with its geometry fixed. This new scheme allowed us to sample the solute molecule quantum mechanically and sample many solvent structures classically. Excitation energy calculations using the selected samples were carried out by the generalized multiconfigurational perturbation theory. We succeeded in constructing the absorption spectra and realizing the red shift of the absorption spectra found in polar solvents. To understand the motion of C120 in water, we carried out principal component analysis and found that the motion of the methyl group made the largest contribution and the motion of the amino group the second largest. The solvent effect on the absorption spectrum was studied by decomposing it in two components: the effect from the distortion of the solute molecule and the field effect from the solvent molecules. The solvent effect from the solvent molecules shows large contribution to the solvent shift of the peak of the absorption spectrum, while the solvent effect from the solute molecule shows no contribution. The solvent effect from the solute molecule mainly contributes to the broadening of the absorption spectrum. In the solvent effect, the variation in C-C bond length has the largest contribution on the absorption spectrum from the solute molecule. For the solvent effect on the absorption spectrum from the solvent molecules, the solvent structure around the amino group of C120 plays the key role.

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Low-Lying Excited States of C120 and C151: A Multireference Perturbation Theory Study

Cited by 12 publications

References 58 publications

Coumarins: Spectroscopic measurements and first principles calculations of C4‐substituted 7‐aminocoumarins

Coumarins: Spectroscopic measurements and first principles calculations of C4‐substituted 7‐aminocoumarins

Aggregation Studies of Dipolar Coumarin-153 Dye in Polar Solvents: A Photophysical Study

Solvent effect on the absorption spectra of coumarin 120 in water: A combined quantum mechanical and molecular mechanical study

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