87986-74-1Relevant academic research and scientific papers
Photoinduced, Direct C(sp2)?H Bond Azo Coupling of Imidazoheteroarenes and Imidazoanilines with Aryl Diazonium Salts Catalyzed by Eosin Y
Saba, Sumbal,Dos Santos, Caio R.,Zavarise, Bruno R.,Naujorks, Aline A. S.,Franco, Marcelo S.,Schneider, Alex R.,Scheide, Marcos R.,Affeldt, Ricardo F.,Rafique, Jamal,Braga, Antonio L.
, p. 4461 - 4466 (2020)
Herein, a greener approach to the eosin Y-Na2 catalyzed, C(sp2)?H bond azo coupling of imidazoheteroarene with aryl diazonium salts is described, under acid free conditions. This direct photoredox process resulted in the corresponding azo products in good to excellent yields. Besides, this new approach could also be applicable to anilines, which is a poorly reactive substrate by other methods. The main features of this reaction are that it provides high yields and is gram-scalable and applicable to biologically relevant imidazoheteroarenes and -anilines.
Photochemically induced structure transfer from analogous azobenzenes and stilbenes onto a liquid crystalline phase
Fischer, Thorsten,Ruhmann, Ralf,Seeboth, Arno
, p. 1087 - 1090 (2007/10/03)
The photoinduced structure transfer from different 4-N,N-diethylamino- 4′-alkoxyazobenzenes and analogous stilbenes onto a nematic liquid crystalline phase has been investigated. The structure transfer caused by the azobenzenes was found to be 7-8 times smaller than for the corresponding stilbenes. The photoinduced E→Z isomerization of the azobenzenes occurred in the liquid crystal more slowly than the thermal back reaction. In contrast, despite lower rate constants for the E→Z photoisomerization, the stilbenes under investigation brought about a greater structure transfer because no thermal back reaction was found at 25 °C. Investigations carried out with the azobenzenes in ethanol and cyclohexane showed the great influence of the polarity of the surrounding medium on the ratio between the rate constants for the E→Z photoisomerization and the thermal Z→E back reaction. This ratio kE→Z/kZ→E,therm increased at 25 °C from ca. 0.15-0.5 in the highly polar liquid crystal to ca. 13-19 in ethanol and nearly 500 in the apolar cyclohexane. This paper concludes that only the investigated stilbenes are suitable for photoaddressed displays using highly polar, thermotropic liquid crystals.
Studies on UV/VIS Absorption Spectra of Azo Dyes. XV. An Analysis of the Absorption Spectra of 4,4'-Diaminoazobenzenes
Haessner, C.,Mustroph, H.
, p. 113 - 119 (2007/10/02)
In the visible absorption spectrum 4,4'-bis-diethylaminoazobenzene shows two absorption maxima (λmax = 426 nm and λmax = 477 nm) with high intensity.Quantum chemical calculations and examinations by peak separation of six 4-substituted azobenzenes and six 4'-substituted 4-diethylaminoazobenzenes (1a-k) indicate that the longest wavelenght band is due to a n-?* transition and the other band is due to a ?-?*-transition.This is verified using an inrement system for ?-?* absorption maxima.A linear relation is found between intensity ratios of the two bands and the HAMMETT-?-constants of the substituents.With increasing electron releasing tendency of the substituents the absorption intensity of the n-?*-band increases.
SOLVENT AND SUBSTITUENT EFFECTS ON THERMAL CIS-TRANS-ISOMERIZATION OF SOME 4-DIETHYLAMINOAZOBENZENES
Marcandalli, Bruno,Pellicciari-Di Liddo, Livia,Di Fede, Cinzia,Bellobono, Ignazio Renato
, p. 589 - 594 (2007/10/02)
Thermal cis-trans-isomerization of some 4'-substituted 4-diethylaminoazobenzenes has been studied.Substitution in the 4'-position leads invariably to an acceleration of the reaction regardless of the nature of the substituent.Logarithms of kinetic constan
