Dynamics of intramolecular processes in electronic-excited states of 2,4,5-triarylimidazole molecules

Intramolecular processes in electronic-excited states of 2,4,5-triarylimidazole molecules were studied by femtosecond laser spectroscopy. Experiments were carried out with two types of compounds, namely, those experiencing intramolecular proton transfer and two model compounds in which it is impossible. Schemes of the processes studied were proposed and the characteristic rate constants were determined. The excited-state intramolecular proton transfer (ESIPT) in the molecules with planar structure of the reaction center is a very fast process (100 fs). If the reaction center has a nonplanar structure and, hence, the intramolecular hydrogen bond is weakened, the ESIPT time is determined by the time of conformational rearrangement of the molecule.     

A Spectral Study of the Complexation between the Hybrid Spiropyran Molecules and Metal Ions

Russian Journal of General Chemistry - The absorption and fluorescent, as well as photochromic properties exhibited by hybrid spiropyran during formation of complexes between its molecules with...     

Kinetics of photochemical reactions of a new biphotochromic compound upon photolysis with light of different wavelengths

Using the method of microsecond flash photolysis with UV and visible light, the spectral and kinetic characteristics of intermediate products of photolysis in toluene and methanol solutions of a new biphotochromic compound have been studied, in which two photochromic moieties, spironaphthoxazine and azomethine, are linked to each other in such a way that there is conjugation between π-electronic systems of the moieties in the ground state of the molecule. Two intermediate products have detected, whose relative efficiency of formation substantially depends on the solvent and the wavelength of excitation light.     

Effect of Substituents on Luminescence of New Hydroxytetraphenylimidazole Derivatives

The effect of OMe and NO₂ substituents in the phenol ring of hydroxytetraphenylimidazole (HTPI) derivatives on their luminescence in solutions and in the solid phase has been studied. The presence of the nitro group leads to multiple luminescence. In addition to the band of the photoproduct of intramolecular proton transfer, which is single for unsubstituted HTPI, nitrosubstituted imidazoles additionally have emission bands at shorter and longer wavelengths. The ratio between the bands depends on the solvent, concentration, and excitation wavelength. In solutions and polymer media, it is possible to switch luminescence by changing the excitation wavelength, and under certain conditions, white light emission is observed.     

Excited-state intramolecular proton transfer in 2,4,5-triarylimidazole molecules

Excited-state intramolecular proton transfer (ESIPT) in the 2,4,5-triarylimidazole molecules was studied by spectral-luminescent technique. For 4,5-diphenyl-(2-hydroxyphenyl)imidazoles, the ESIPT occurs in both liquid and glassy matrices at 77 K. For 4,5-diphenyl-(2-hydroxynaphthyl)imidazole, the ESIPT requires rotation of molecular fragments and is not observed at 77 K.     

Photochromic properties of the bichromophore spirooxazine and its complexes with metal cations

The properties of a bichromophore photochromic spirooxazine with a hydroxynaphthylideneimine fragment in position 8 were studied in solutions in the presence of alkali and alkaline earth metal salts. The changes in the absorption spectra of the initial form of this compound upon complexation are due to the electron density redistribution in the conjugation chain due to the incorporation of the metal cation into the ionophoric center of the chelating molecule. A complexation scheme was proposed and the stability constants of the resulting complexes were estimated. The complexation of the photoinduced merocyanine form of the compound increases its lifetime. This process is due to the interaction of the metal ion with both the chelating ionophoric center and the oxygen atom of the mercocyanine form. The efficiency of complexation of both the initial and the merocyanine forms depends on the electrostatic properties of the metal cations. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1434–1437, June, 2005.     

Spectral and Kinetic Studies of Photochromic Systems Based on Graphene and Graphene Oxide Nanostructures

Optics and Spectroscopy - A comparative spectral and kinetic study of the reactions of thiol-substituted molecules of diarylethene and spirooxazine with graphene nanoparticles and graphene oxide...     

HYDROGEN BONDING IN THE CRYSTAL OF 1,1′-((1E,1′E)-(PYRIDINE-3,4-DIYLBIS (AZANYLYLIDENE))BIS(METHANYLYLIDENE))- BIS(NAPHTHALEN-2-OL) ACETONITRILE SOLVATE: COMBINED EXPERIMENTAL AND THEORETICAL STUDY

Journal of Structural Chemistry - The title compound, 1,1′-((1E,1′E)-(pyridine-3,4-diylbis(azanylylidene))bis(methanylylidene))bis (naphthalen-2-ol) (1), was synthesized and...