A series of substituted oxazolylfulgides have been prepared as photochromic compounds which color in the yellow region on irradiation with UV light. Some of them exhibit favorable features as photochromic yellow dyes in polymer film with fairly good photochemical reversibility, coloration quantum yields, and thermal stability.
Synthesis and spectral properties of 3-(2-aryl-5-methyl-1,3-oxazol- 4-yl)-2-(2,5-dimethylthiophen-3-yl)cyclopent-2-en-1-ones
作者:Andrey G. Lvov、Valerii Z. Shirinian、Alexey M. Kavun、Mikhail M. Krayushkin
DOI:10.1016/j.mencom.2014.09.010
日期:2014.9
Alkylation of ethyl 4-(2,5-dimethylthiophen-3-yl)-3-oxobutanoate with 2-aryl-4-bromoacetyl-5-methyl-1,3-oxazole followed by decarboxylation cyclization of the intermediate, diketo ester affords the title photochromic compounds. Relationship between the fluorescent characteristics, thermal stability of photoinduced form as well as quantum yields of photochemical reactions and the structure of these compounds was evaluated.
Synthesis and photophysical studies of oxazole rings containing compounds as electron accepting units
A series of oxazole derivatives, 5-methyl-2-(p-methylphenyl)-4-acetyl oxazole (MMPAO), 5-methyl-2-(p-methoxyphenyl)-4-acetyl oxazole (MOPAO), 5-methyl-2-(p-N,N'-dimethylamino-phenyl)-4-acetyl oxazole (MDMAPAO) and 5-methyl-2-(p-N,N-diphenylaminophenyl)-4-acetyl oxazole (MDPAPAO) have been synthesized and studied to compare their photophysical properties. The UV-visible absorption spectra of MDMAPAO and MDPAPAO are bathochromatically shifted as compared to that of MMPAO and MOPAO. The fluorescence emission of MDPAPAO is very sensitive to the polarity of solvents. The magnitude of change in the dipole moment was calculated using the Lippert-Mataga equation. MDPAPAO shows the highest change in the dipole moment (Delta u = 13.3D) than that of the other three oxazole derivatives. The spectral properties including fluorescence quantum yield and lifetime were determined in solvents with different polarities. MDPAPAO displays the highest fluorescence quantum yield and lifetime, following a bi-exponential fluorescent decay fashion. Our result demonstrates that the excited state of MDPAPAO possesses the property of intramolecular charge transfer. (C) 2012 Elsevier B.V. All rights reserved.
The synthesis of some substituted 4-acetyl-oxazoles and the corresponding acids
作者:A. W. Allan、B. H. Walter
DOI:10.1039/j39680001397
日期:——
condensation of aromatic aldehydes with hydroxyimino-β-diketones in the presence of dry hydrogen chloride and reduction of the intermediate N-oxides. The acetyl-oxazoles were oxidised to the correspondingacids with sodium hypobromite.
by deoxygenation of the corresponding N-oxides has been developed. As the deoxygenation reagent, a previously unknown complex of collidine with phosphorus trichloride in a 2:1 ratio has been used. The developed method enabled the preparation of a wide range of 2-aryl-1,3-oxazoles comprising various functional groups in good yields. The advantage of this reagent is its tolerance to nitro, methyl, hydroxyl