scholarly journals Photophysical Properties of The DCM and DFSBO Styryl Dyes Consequence for Their Laser Properties

1990 ◽  
Vol 10 (5-6) ◽  
pp. 277-296 ◽  
Author(s):  
Jean-Claude Mialocq ◽  
Martine Meyer
Keyword(s):  
Excited States ◽  
Intramolecular Charge Transfer ◽  
Dipole Moments ◽  
Photophysical Properties ◽  
Stokes Shift ◽  
Emission Spectra ◽  
Intersystem Crossing ◽  
Laser Dye ◽  
Styryl Dyes ◽  
Polar Solvents

The two styryl dyes, 4-dicyanomethylene-2-methyl-6-P-dimethylaminostyryl-4H-pyran (DCM) and 7- dimethylamino-3-(p-formylstyryl)-l, 4-benzoxazin-2-one (DFSBO) exhibit similar solvent-induced shifts of their absorption and emission spectra related to a large intramolecular charge transfer (ICT) in the first singlet excited state. From the Stokes shift values (vA−vF) and a vectorial analysis of their ground state dipole moment (μg= 6.1 D for DCM and 5.8 D for DFSBO), and using the Lippert-Mataga theory, we have estimated the dipole moments of their fluorescent excited states S1 (μe = 26.3 D for DCM and 27.6 D for DFSBO). Intersystem crossing to the triplet state is totally inefficient in DCM but significant in DFSBO. Moreover the absorption of the DFSBO triplet is quite large in the emission band (600–650 nm), which makes of DFSBO a poor laser dye. Although DCM trans-cis photoisomerization can be quite efficient in non polar solvents (chloroform, tetrahydrofuran), DFSBO does not photoisomerize probably due to steric hindrance and to the S1 character which should be more "benzoxazinone" than ethylenic. DFSBO is also shown to exhibit rotamerism.

Solvent sensitive intramolecular charge transfer dynamics in the excited states of 4-N,N-dimethylamino-4′-nitrobiphenyl

2016 ◽  
Vol 18 (11) ◽  
pp. 7661-7671 ◽  
Author(s):  
Rajib Ghosh ◽  
Amitabha Nandi ◽  
Dipak K. Palit
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Triplet State ◽  
Excited States ◽  
Intramolecular Charge Transfer ◽  
Intersystem Crossing ◽  
Polar Solvents ◽  
Excited State Dynamics ◽  
Nonpolar Solvents ◽  
Charge Transfer Dynamics

Solvent sensitive excited state dynamics of DNBP is explored. In polar solvents, the ultrafast barrierless TICT process is the major relaxation pathway, whereas, in nonpolar solvents the excited state undergoes the PICT process, followed by efficient intersystem crossing to the triplet state.

Excited States Dipole Moments and Fluorescence Behaviour of Some Derivatives of Dimethylaminobenzonitrile

1990 ◽  
Vol 45 (7) ◽  
pp. 883-888
Author(s):  
C. Brittinger ◽  
A. K. Maiti ◽  
W. Baumann ◽  
N. Detzer
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Charge Transfer ◽  
Excited States ◽  
Intramolecular Charge Transfer ◽  
Dipole Moments ◽  
Solvent Polarity ◽  
Polar Solvents ◽  
Derivatives Of ◽  
Limiting Value

AbstractTwo sterically hindered derivatives of dimethylaminobenzonitrile (DMCA) have been synthesized and the dipole moment of their fluorescent excited state has been determined in differently polar solvents. Its value increases with solvent polarity up to a limiting value of (50 + 2.5) • 10-30 Cm. The results are discussed with reference to the twisted intramolecular charge transfer (TICT) state formation in the class of molecules related to DMCA.

scholarly journals Studies on Photophysical Properties of Mono-carbonyl Curcumin Analogues: Experimental and Theoretical approach

2018 ◽  
Vol 34 (4) ◽  
pp. 2170-2179
Author(s):  
Manjula Rayanal ◽  
Prasad Pralhad Pujar ◽  
Sridhar D
Keyword(s):  
Excited State ◽  
Ground State ◽  
Dipole Moments ◽  
Photophysical Properties ◽  
Stokes Shift ◽  
Solvent Polarity ◽  
Frontier Molecular Orbital ◽  
Curcumin Analogues ◽  
Td Dft ◽  
Ground State Dipole Moments

The solvatochromic fluorescence behaviour of mono-carbonyl curcumin analogues has been studied in ten different solvents ranging from non-polar to polar. The solvent effect on the spectral properties of analogues has been discussed. The ground state dipole moments were estimated experimentally by Bilot-Kawski equation which is a function of Stokes shift with the solvent polarity parameters and Guggenheim method and theoretically by TD-DFT studies. The excited state dipole moment was determined using Bilot-Kawski equations. The excited state dipole moments for the two molecules were found to be higher than their corresponding ground state dipole moments. Theoretically Frontier molecular orbital (HOMO/ LUMO) energies were determined by Gaussian 09 W software using TD-DFT.

The Electric Dipole Moments of Methine Dyes – Comparison of Experimental Results with Theoretical Predictions

1982 ◽  
Vol 37 (9) ◽  
pp. 1024-1026
Author(s):  
Z. Salamon ◽  
A. Skibiński ◽  
K. Celnik
Keyword(s):  
Dipole Moments ◽  
Stokes Shift ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Electronic Charge ◽  
Excited Singlet ◽  
Nonpolar Solvents ◽  
Singlet States ◽  
Theoretical Predictions ◽  
Excited Singlet States

Abstract Absorption and emission spectra of methine dyes in polar and nonpolar solvents were measured. From the Stokes shift as a function of solvent polarity the dipole moments of excited singlet states have been estimated and compared with the quantum chemical predictions. Also the π-electronic charge distribution in the ground and first excited singlet electronic states and bond orders of the dyes were calculated. All investigated methines showed an increase in dipole moment upon excitation to the first excited emitting state.

Spectroscopic Studies of Dimethylamino Derivatives of Fluorene

2000 ◽  
Vol 55 (11-12) ◽  
pp. 902-908 ◽  
Author(s):  
J. Heldt ◽  
J. R. Heldt ◽  
T. Redzimski ◽  
H. Diehl ◽  
P. Schultz
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Charge Transfer ◽  
Fluorescence Spectra ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Spectroscopic Studies ◽  
Polar Solvents ◽  
Derivatives Of ◽  
Transfer State

Abstract 2-dimethylamino-9-fluorenol and 2-dimethylamino-9(4'dimethylamino)phenyl-9-fiuorenol in polar solvents in the excited state undergo conformation changes in which two fluorescent isomers are created. The isomers (in the local excited (LE) and charge transfer (CT) configuration) possess separate fluorescence bands, one appearing from the S1 (LE) state and the second from the intramolecular charge transfer state S1 (CT) of the neutral, aromatic molecule. Both bands show a solvatochromic effect. Using the method of the solvent induced Stokes shift of the absorption and fluorescence spectra the permanent dipole moment of the excited state of fluorene and its two derivatives have been determined. The dipole moment of the ground state and the Onsager cavity radius of the studied molecules were calculated with the Auestion Model 1 (AM1) program.

scholarly journals Photophysical Properties of Nitrated and Halogenated Phosphorus Tritolylcorrole Complexes: Insights from Theory

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2779 ◽  
Author(s):  
Marta Alberto ◽  
Bruna De Simone ◽  
Gloria Mazzone ◽  
Nino Russo ◽  
Marirosa Toscano
Keyword(s):  
Excited States ◽  
Density Functional ◽  
Energy Gap ◽  
Photophysical Properties ◽  
Intersystem Crossing ◽  
Triplet States ◽  
Excited Singlet ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Singlet And Triplet States

The photophysical properties of a series of nitrated and halogenated phosphorus tritolylcorrole complexes were studied in dichloromethane solvent by using the density functional theory. Particular emphasis was given to the absorption spectra, the energy gap between the excited singlet and triplet states, and the magnitude of the spin-orbit couplings for a series of possible intersystem crossing channels between those excited states. The proposed study provides a better description of the photophysical properties of these systems while giving insights into their possible use as photosensitizers in photodynamic therapy.

scholarly journals The Synthesis and Photophysical Properties of Weakly Coupled Diketopyrrolopyrroles

Molecules ◽  
2021 ◽  
Vol 26 (16) ◽  
pp. 4744
Author(s):  
Michał Pieczykolan ◽  
James B. Derr ◽  
Amara Chrayteh ◽  
Beata Koszarna ◽  
John A. Clark ◽  
...  
Keyword(s):  
Excited States ◽  
Density Functional ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Photophysical Properties ◽  
Electronic Transitions ◽  
Intersystem Crossing ◽  
Straightforward Manner ◽  
Functional Theory ◽  
Weakly Coupled

Three centrosymmetric diketopyrrolopyrroles possessing either two 2-(2′-methoxyphenyl)benzothiazole or two 2-(2′-methoxyphenyl)benzoxazolo-thiophene scaffolds were synthesized in a straightforward manner, and their photophysical properties were investigated. Their emission was significantly bathochromically shifted as compared with that of simple DPPs reaching 650 nm. Judging from theoretical calculations performed with time-dependent density functional theory, in all three cases the excited state was localized on the DPP core and there was no significant CT character. Consequently, emission was almost independent of solvents’ polarity. DPPs possessing 2,5-thiophene units vicinal to DPP core play a role in electronic transitions, resulting in bathochromically shifted absorption and emission. Interestingly, as judged from transient absorption dynamics, intersystem crossing was responsible for the deactivation of the excited states of DPPs possessing para linkers but not in the case of dye bearing meta linker.

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