Ground and excited state dipole moments of 1-methylindole from thermochromic shifts in absorption and emission spectra

2021 ◽  
Vol 406 ◽  
pp. 112984
Author(s):  
Mirko Matthias Lindic ◽  
Michael Schmitt
Keyword(s):  
Excited State ◽  
Dipole Moments ◽  
Emission Spectra ◽  
Absorption And Emission ◽  
Absorption And Emission Spectra ◽  
Excited State Dipole Moments

DFT Study of Substituted Effect on Absorption and Emission Spectra of Naphthoquinone Derivatives

2011 ◽  
Vol 233-235 ◽  
pp. 1878-1883 ◽  
Author(s):  
Li Zhi Wang ◽  
Run Zhou Su ◽  
Shuo Qi ◽  
Wei Yu Gong ◽  
Tai Min Cheng
Keyword(s):  
Excited State ◽  
Density Functional ◽  
Visible Region ◽  
Emission Spectra ◽  
Electron Transition ◽  
Functional Theory ◽  
Absorption And Emission ◽  
Absorption And Emission Spectra ◽  
The Density Functional Theory ◽  
Substituted Effect

The density functional theory (DFT) is used to compute the ground-state geometries of naphthoquinone derivatives, and lowest singlet excited-state geometries of them have been investigated by the singles configuration interaction (CIS) method. The absorption and emission spectra are calculated by time-dependent DFT (TDDFT) on the basis of the ground- and excited-state geometries, respectively. Our calculations are in good agreement with the available experimental results. The calculated results show that with the introduction of hydroxyl the red-shift was found in the absorption and emission, and the range of spectra reach the visible region. Furthermore, in the absorptions electron transition type was identified from the point-view of molecular orbitals. Study of the effect of hydroxyl and site on spectra can provide the helpful information on further designing molecular devices.

A study of photocyclization of O-alkyl N-(3-chloro-2-benzo[b]thienocarbonyl)monothiocarbamates

1986 ◽  
Vol 51 (9) ◽  
pp. 2002-2012 ◽  
Author(s):  
Peter Kutschy ◽  
Ján Imrich ◽  
Juraj Bernát ◽  
Pavol Kristian ◽  
Iveta Fedoriková
Keyword(s):  
Excited State ◽  
Complex Formation ◽  
Emission Spectra ◽  
Radical Mechanism ◽  
Singlet Excited State ◽  
Model Compounds ◽  
Reaction Conditions ◽  
Absorption And Emission ◽  
Absorption And Emission Spectra ◽  
High Yields

The O-alkyl N-(3-chloro-2-benzo[b]thienocarbonyl)monothiocarbamates prepared by the reaction of 2-isothiocyanatocarbonyl-3-chlorobenzo[b]thiophene with methanol, ethanol, 1-propanol, and 2-propanol are cyclized on irradiation with light of the wavelength above 300 nm to give high yields (80-90%) of 2-alkoxy-4H-benzo[b]thieno[2,3-e]-1,3-thiazin-4-one derivatives. From the absorption and emission spectra of the starting compounds as well as from a study of model compounds and influence of the reaction conditions it is presumed that the investigated intramolecular photosubstitution of chlorine by sulphur proceeds from the first singlet excited state (π, π*) by a radical mechanism through the phase of radical complex formation.

scholarly journals Relations between absorption, emission, and excited state chemical potentials from nanocrystal 2D spectra

2021 ◽  
Vol 7 (22) ◽  
pp. eabf4741
Author(s):  
Jisu Ryu ◽  
Samuel D. Park ◽  
Dmitry Baranov ◽  
Iva Rreza ◽  
Jonathan S. Owen ◽  
...  
Keyword(s):  
Excited State ◽  
Single Molecule ◽  
Chemical Potential ◽  
Emission Spectra ◽  
Optical Methods ◽  
Chemical Potential Difference ◽  
Absorption And Emission ◽  
Absorption And Emission Spectra ◽  
Standard Chemical Potential ◽  
Size Dispersion

For quantum-confined nanomaterials, size dispersion causes a static broadening of spectra that has been difficult to measure and invalidates all-optical methods for determining the maximum photovoltage that an excited state can generate. Using femtosecond two-dimensional (2D) spectroscopy to separate size dispersion broadening of absorption and emission spectra allows a test of single-molecule generalized Einstein relations between such spectra for colloidal PbS quantum dots. We show that 2D spectra and these relations determine the thermodynamic standard chemical potential difference between the lowest excited and ground electronic states, which gives the maximum photovoltage. Further, we find that the static line broadening from many slightly different quantum dot structures allows single-molecule generalized Einstein relations to determine the average single-molecule linewidth from Stokes’ frequency shift between ensemble absorption and emission spectra.

scholarly journals Estimating the Ground and Excited State Dipole Moments of Levofloxacin and Norfloxacin Drugs Using Solvatochromic Effects and Computational Work

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Kinfe Woldegiorges ◽  
Abebe Belay ◽  
Alemu Kebede ◽  
Tamirat Abebe
Keyword(s):  
Excited State ◽  
Ground State ◽  
Dipole Moments ◽  
Bacterial Species ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Electron Charge Density ◽  
Nonpolar Solvents ◽  
Computational Work ◽  
Excited State Dipole Moments

Levofloxacin (LVF) and norfloxacin (NRF) are a group of fluoroquinolone antibiotics, broad spectrum used to treat various infections caused by many bacterial species. The drugs contain functional groups which control the type and degree of interaction with different solvents. In this research, the ground and excited state dipole moments of LVF and NRF drugs were estimated using solvatochromic effects and computational work. The dipole moments were estimated from absorption and emission spectra in polar and nonpolar solvents using Bakhshiev’s, Kawski–Chamma–Viallet, Lippert–Mataga, and Reichardt models. The results indicated the emission spectra are more strongly affected by solvent polarity than the absorption spectra. The calculated excited state dipole moment is larger than that of the ground state, indicating that the probe compounds are significantly more polarized in the excited state than in the ground state. From computational work, the HOMO-LUMO energy band gap, the dipole moments, electron charge density distribution, and oscillator strength were determined using the semiempirical MP6 method, DFT-B3LYP-6-31G, and DFT-B3LYP-3-21G employing Gaussian 09 software. In general, larger dipole moments were obtained by computation rather than from experiments due to the absence of solvent effects.

Studies of the photophysics and spectroscopy of alloxazine and related compounds in solution and in the solid state

1999 ◽  
Vol 77 (4) ◽  
pp. 472-480 ◽  
Author(s):  
M Sikorski ◽  
E Sikorska ◽  
F Wilkinson ◽  
R P Steer
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Homogeneous Solution ◽  
Emission Spectra ◽  
Quantum Yields ◽  
Adsorbed State ◽  
Absorption And Emission ◽  
Absorption And Emission Spectra ◽  
Excited State Proton Transfer ◽  
Emitting Species

The absorption and emission spectra and the fluorescence lifetimes and quantum yields of alloxazine and several of its N- and C- methyl-substituted derivatives, including two isoalloxazines, have been measured in a nonpolar solvent (1,2-dichloroethane), a polar aprotic solvent (acetonitrile), and a polar protic solvent (ethanol). The excited state decays are all single exponential, suggesting that only one emitting species is present in all cases. The spectroscopic data show that the emitting species is the π,π* electronic excited state corresponding to the ground state of the absorbing molecule; there is no evidence of excited state proton transfer for any of these solutes in any of the three solvents. The longer lifetimes and larger fluorescence quantum yields of the isoalloxazines compared with the alloxazines can be attributed exclusively to significantly slower rates of radiationless relaxation in the excited isoalloxazines. The remission and emission spectra of these same compounds adsorbed on cellulose are similar to the corresponding absorption and emission spectra in homogeneous solution, suggesting that the emitting species are the same in the adsorbed state as they are in homogeneous solution. However, the adsorbed excited species exhibit non-exponential temporal decay, attributed to inhomogeneities in the binding of the chromophore to cellulose. The emission spectra of polycrystalline samples of alloxazine and lumichrome suggest the possible occurrence of double intermolecular excited state proton transfer, but this interpretation is not supported by the further photophysical data obtained here.Key words: photophysics, spectroscopy, alloxazine, lumiflavin, cellulose.

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