RESUMO
The synthesis of a new structural class of isoindoline nitroxides (aminoxyls), accessible via the palladium-catalysed Heck reaction, is presented. Reaction of the aryl bromoamine, 5-bromo-1,1,3,3-tetramethylisoindoline (4) or dibromoamine, 5,6-dibromo-1,1,3,3-tetramethylisoindoline (5) or the analogous bromonitroxides 6 and 7 with methyl acrylate gives the acrylate substituted tetramethylisoindoline amines 8 and 10 and nitroxides 12 and 14. Similarly, the reaction of the aryl bromides and dibromides 4-7 with methyl 4-vinylbenzoate gives the carboxystyryl substituted tetramethylisoindoline amines 9 and 11 and the analogous nitroxides 13 and 15. The carboxystyryl tetramethylisoindoline nitroxides demonstrate strongly suppressed fluorescence, which is revealed upon removal of the free radical by reduction or radical coupling.
Assuntos
Alcenos/química , Indóis/química , Óxidos de Nitrogênio/química , Paládio/química , Estilbenos/química , Antioxidantes/síntese química , Antioxidantes/química , Catálise , Fluorescência , Indóis/síntese química , Estrutura Molecular , Óxidos de Nitrogênio/síntese químicaRESUMO
Infrared spectroscopy has been used to characterise synthesised hydrotalcites of formula Mg(x)Zn(6 - x)Cr2(OH)16(CO3) x 4H2O and Ni(x)Co(6 - x)Cr2(OH)16(CO3) x 4H2O. The infrared spectra are conveniently subdivided into spectral features based (a) upon the carbonate anion (b) the hydroxyl units (c) water units. Three carbonate antisymmetric stretching vibrations are observed at around 1358, 1387 and 1482 cm(-1). The 1482 cm(-1) band is attributed to the CO stretching band of carbonate hydrogen bonded to water. Variation of the intensity ratio of the 1358 and 1387 cm(-1) modes is linear and cation dependent. By using the water bending band profile at 1630 cm(-1) four types of water are identified (a) water hydrogen bonded to the interlayer carbonate ion (b) water hydrogen bonded to the hydrotalcite hydroxyl surface (c) coordinated water and (d) interlamellar water. It is proposed that the water is highly structured in the hydrotalcite interlayer as it is hydrogen bonded to both the carbonate anion, adjacent water molecules and the hydroxyl surface.
Assuntos
Cromo/análise , Cobalto/análise , Magnésio/análise , Níquel/análise , Água/química , Zinco/análise , Hidróxido de Alumínio/química , Ânions , Carbono/química , Cromo/química , Cobalto/química , Ligação de Hidrogênio , Íons , Magnésio/química , Hidróxido de Magnésio/química , Níquel/química , Espectrofotometria Infravermelho , Zinco/químicaRESUMO
The vibrational spectra of pseudomalachite, reichenbachite and ludjibaite have been obtained at 298 K using a combination of FTIR and Raman microscopy. The vibrational spectra of the minerals are different, in line with differences in crystal structure and composition. Some similarity in the Raman spectra of the three polymorphs pseudomalachite, reichenbachite and ludjibaite exists, particularly in the OH stretching region, but characteristic differences in the OH deformation regions are observed. Differences are also observed in the phosphate stretching and deformation regions.
