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.     

Asymmetric nitrogen−35 : Structure and properties of l(s)-α-carboxyethyl-3, 3-bis(trifluoromethyl)diaziridine and its derivatives

A second-kind asymmetric transformation involving N-atom inversion has been observed at 20° for 1(S) - α - carboxyethyl - 3,3 - bis(trifluoromethyl)diaziridine 1 and its methyl ester 2. X-Ray data for the diastereomer (1S, 2S, α-S), 1A (which is thermodynamically preferred in the crystalline phase), ¹H NMR spectra of ethyl ester 3-¹⁵N(1) and 3-¹⁵N(2), CD spectra of 1A,B, 2A,B, potassium salt 4A,B and semiempirical calculations (MINDO/3 and INDO) for 1A, show that the stereospecificity of crystallization of the diastereomer A is due to the higher energy of the crystal lattice of the diastereomer (1R, 2R, α-S), 1B because of hindered charge compensation as well as to the hindrance by the CF₃, groups to intermolecular H-bonds. According to semiempirical calculations, the stability of 3,3 - bis(trifluoromethyl) - diaziridines (TFD) to the action ofel w-orbital energies and depolarization of the C-N bonds due to hyperconjugation and the inductive effect of the CF₃,-groups. The steric effect of these groups is the reason of the low configurational stability of TFD compared with the 3,3-dimethyl analogues.     

Magnetoelectrolytic Dispersion of Ferromagnetic Metals

Processes of electrolytic dispersion of ferromagnetic metals (nickel and cobalt) to give oxides or metal powders were studied. The influence of an external magnetic field and current reversal on the processes of anodic dissolution was analyzed.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 6, 2005, pp. 924–927.Original Russian Text Copyright © 2005 by Zaichenko.     

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.     

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...     

2-Alkylisoxazolidine-3,3-dicarboxylic acid derivatives

1,3-Dipolar cycloaddition of,-bis(alkoxycarbonyl)-N-alkylnitrones to olefins gave 2-alkylisoxazolidine-3,3-dicarboxylic acid esters, the yields of which are determined by the steric conditions and are virtually independent of the electronic effect of the substituents attached to the C=C bond of the dipolarophiles. The structures of the compounds obtained were established by analysis of the PMR spectra. The retention of the cis configuration of the substituents in the isoxazolidines obtained from maleic acid esters constitutes evidence for a one-step, four-center, concerted cycloaddition mechanism. The energy parameters for inversion of the nitrogen atom of dimethyl 2,5,5-trimethylisoxazolidine-5,5-dicarboxylate were measured.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 599–603, May, 1979.