Etude spectroscopique de l'aniline dans les solvants

1975 ◽  
Vol 53 (10) ◽  
pp. 1461-1467 ◽  
Author(s):  
P. Méallier ◽  
A. Berthelon ◽  
B. Pouyet
Keyword(s):  
Molecular Structure ◽  
Dipole Moment ◽  
Excited State ◽  
Charge Transfer ◽  
Ground State ◽  
Aromatic Amines ◽  
Photochemical Oxidation ◽  
Transfer Effects ◽  
Absorption Bands ◽  
Oxidation Processes

The effect of change of solvent on the positions and intensities of absorption bands of some aromatic amines between 200 and 400 nm has been examined. In particular, the behavior of the band at 280 nm has been studied.In hydroxylic solvents, this band is displaced towards shorter wavelengths, and the dipole moment in the excited state of the molecule is smaller than in the ground state. The opposite effects are found when nonhydroxylic solvents are used.The results show how the molecular structure is altered by charge transfer effects and can explain how different solvents affect photochemical oxidation processes.

Electroabsorption spectra of push–pull porphyrins in solution and in solid films

2015 ◽  
Vol 19 (01-03) ◽  
pp. 527-534
Author(s):  
Kamlesh Awasthi ◽  
Hung-Yu Hsu ◽  
Hung-Chu Chiang ◽  
Chi-Lun Mai ◽  
Chen-Yu Yeh ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Charge Transfer ◽  
Electric Dipole Moment ◽  
Electric Dipole ◽  
Ground State ◽  
Benzene Solution ◽  
Solid Films ◽  
The One ◽  
Interfacial Charge

Polarized electroabsorption (E-A) spectra of highly efficient porphyrin sensitizers (YD2 and YD2-oC8) have been measured in benzene solution. Polarized E-A spectra of these push–pull porphyrins embedded in poly(methyl methacrylate) films or sensitized on TiO 2 films are also observed. Based on the analysis of the E-A spectra, the magnitude of the electric dipole moment both in the ground state and in the lowest excited state have been evaluated in solution and in solid films. The electric dipole moment in the excited state of these compounds is very large on TiO 2 films, suggesting the interfacial charge transfer on TiO 2 surface following photoexcitation of porphyrin dyes. The electric dipole moment in the excited state evaluated from the E-A spectra is very different from the one evaluated from the electrophotoluminescence spectra on TiO 2, suggesting that the strong local field of TiO 2 films is applied to the fluorescing dyes attached to TiO 2 films.

scholarly journals Theoretical research on excited-state intramolecular proton coupled charge transfer modulated by molecular structure

RSC Advances ◽  
2018 ◽  
Vol 8 (52) ◽  
pp. 29662-29669
Author(s):  
Dapeng Yang ◽  
Guang Yang ◽  
Min Jia ◽  
Xiaoyan Song ◽  
Qiaoli Zhang ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Energy Barrier ◽  
Theoretical Research ◽  
Small Energy

Charge transfer from O1 to O2 of 3HFN results in proton H1 transfer from O1 to O2 in S1 state, while small energy barrier facilitates proton H1 transfer from O1 to N1 in S1 state of diCN-HBO, which results in charge transfer from O1 to di-cyano.

Radiationless Deactivation of an Intramolecular Charge Transfer Excited State through Hydrogen Bonding:  Effect of Molecular Structure and Hard−Soft Anionic Character in the Excited State

2001 ◽  
Vol 105 (45) ◽  
pp. 10488-10496 ◽  
Author(s):  
Akimitsu Morimoito ◽  
Tomoyuki Yatsuhashi ◽  
Tetsuya Shimada ◽  
László Biczók ◽  
Donald A. Tryk ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonding ◽  
Excited State ◽  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Bonding Effect ◽  
Hydrogen Bonding Effect

scholarly journals Ingenious modification of molecular structure effectively regulates excited-state intramolecular proton and charge transfer: a theoretical study based on 3-hydroxyflavone

RSC Advances ◽  
2018 ◽  
Vol 8 (52) ◽  
pp. 29589-29597 ◽  
Author(s):  
Jianhui Han ◽  
Xiaochun Liu ◽  
Chaofan Sun ◽  
You Li ◽  
Hang Yin ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Excited State ◽  
Charge Transfer ◽  
Proton Transfer ◽  
Theoretical Study ◽  
Intramolecular Charge Transfer ◽  
Intramolecular Proton Transfer ◽  
Great Promise ◽  
Fluorescence Sensing

Harnessing ingenious modification of molecular structure to regulate excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) characteristics holds great promise in fluorescence sensing and imaging.

Organometallic ferromagnets

1990 ◽  
Vol 330 (1610) ◽  
pp. 205-215 ◽  
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Ground State ◽  
Magnetic Coupling ◽  
Organometallic Complexes ◽  
Electron Configuration ◽  
Ferromagnetic Coupling ◽  
New Materials ◽  
Linear Chains ◽  
Configuration Mixing

Some organometallic solids comprising linear chains of alternating m 8 = 1/2 metallocenium donors, D, and cyanocarbon acceptors, A, i.e. ••• D +*A~*D+*A- * •••, exhibit cooperative magnetic phenomena, i.e. ferro-, antiferro-, ferri-, and meta-magnetism. For [Fe II (C 5 Me 5 ) 2 ]+*[T C N E ]- (Me = methyl; T C N E = tetracyanoethylene) bulk ferromagnetic behaviour is observed below the Curie temperature of 4.8 K. Replacement of Fe III with Fe II , Ni III and Cr III leads to complexes with dia-, antiferro- and ferrimagnetic behaviour, respectively. These results are consistent with a model of configuration mixing of the lowest charge transfer excited state with the ground state developed earlier to understand the magnetic coupling of such systems. The model predicts the magnetic coupling as a function of electron configuration and direction of charge transfer (retro or reverse) and is a useful guide to designing new organic and /or organometallic complexes with cooperative magnetic coupling. To test the model and identify new materials with ferromagnetic coupling new TCNE-based electron transfer salts were prepared.

scholarly journals Role of active site conformational changes in photocycle activation of the AppA BLUF photoreceptor

2017 ◽  
Vol 114 (7) ◽  
pp. 1480-1485 ◽  
Author(s):  
Puja Goyal ◽  
Sharon Hammes-Schiffer
Keyword(s):  
Electron Transfer ◽  
Free Energy ◽  
Excited State ◽  
Charge Transfer ◽  
Conformational Changes ◽  
Ground State ◽  
Active Site ◽  
Locally Excited ◽  
Proton Relay ◽  
Locally Excited State

Blue light using flavin adenine dinucleotide (BLUF) proteins are essential for the light regulation of a variety of physiologically important processes and serve as a prototype for photoinduced proton-coupled electron transfer (PCET). Free-energy simulations elucidate the active site conformations in the AppA (activation of photopigment and puc expression) BLUF domain before and following photoexcitation. The free-energy profile for interconversion between conformations with either Trp104 or Met106 closer to the flavin, denoted Trpin/Metout and Trpout/Metin, reveals that both conformations are sampled on the ground state, with the former thermodynamically favorable by ∼3 kcal/mol. These results are consistent with the experimental observation of both conformations. To analyze the proton relay from Tyr21 to the flavin via Gln63, the free-energy profiles for Gln63 rotation were calculated on the ground state, the locally excited state of the flavin, and the charge-transfer state associated with electron transfer from Tyr21 to the flavin. For the Trpin/Metout conformation, the hydrogen-bonding pattern conducive to the proton relay is not thermodynamically favorable on the ground state but becomes more favorable, corresponding to approximately half of the configurations sampled, on the locally excited state. The calculated energy gaps between the locally excited and charge-transfer states suggest that electron transfer from Tyr21 to the flavin is more facile for configurations conducive to proton transfer. When the active site conformation is not conducive to PCET from Tyr21, Trp104 can directly compete with Tyr21 for electron transfer to the flavin through a nonproductive pathway, impeding the signaling efficiency.

Molecular and structural characterization of New Red and Erythrosine by fluorescence polarization spectroscopy

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740062
Author(s):  
Chun Zhu ◽  
Jia-Meng Du ◽  
Jin-Chen Zhao ◽  
Tuo Zhu ◽  
Guo-Qing Chen
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Ground State ◽  
Dipole Moments ◽  
Linear Structure ◽  
Polarization Spectroscopy ◽  
Angle Shift ◽  
Ground State Structures ◽  
Average Angle

The fundamental and the fluorescence anisotropies of New Red and Erythrosine were measured. The intersection angles between the absorption and the emission dipole moments for New Red and Erythrosine are 4.44[Formula: see text] and 23.26[Formula: see text], respectively. The average angle shift of the emission dipole moment of New Red is 3.91[Formula: see text] during the lifetime of the excited state. This indicates that it has a bifurcated linear structure with weak rotational capacity. The average angle shift of the emission dipole moment of Erythrosine is 9.25[Formula: see text], indicating that it has a partial planar structure and is easier to rotate. The spatial ground state structures were simulated with Gaussian 09.

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