- Carbazole N-substituent effect upon DTMA: Stabilizing and photochromic modulating
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Dithienylmaleimide derivatives 7-27 were synthesized by introducing N-substituted carbazole for photo-stabilizing purpose, and the structures were fully confirmed. The photochromism and photo-stability were recorded via UV-vis spectra. Only ortho compounds 8-17 with N-substituents on carbazole moiety showed escalated photochromic change, while compound 7 and the para counterparts 18-27 showed no appreciable photochromism. Additionally, compounds 8-18 exhibited good photo-stability except 17 under 254 nm irradiation. The unstability of 17 may probably due to overrunning hindrance. These photochromic patterns indicated that hindrance and electronic effect mutually paid a decisive influence on the photochromism and photo-stability, which potentially exploited a new way to construct novel photochromic materials with regulable and conceivable performance.
- Huo, Zhiming,Li, Zhipeng,Wang, Tingting,Zeng, Heping
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supporting information
p. 8964 - 8973
(2013/09/23)
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- Preparation and study of 1,8-di(pyrid-2′-yl)carbazoles
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(Figure Presented) A series of three derivatives of 1,8-di(pyrid-2′- yl)carbazole were prepared by Stille-type coupling of 2-(tri-n-butylstannyl) pyridine with the appropriate 1,8-dibromocarbazole. The carbazoles were prepared by appropriate substitution methodologies on the parent carbazole or by palladium-catalyzed cyclization of di-(p-tolyl)amine to provide the carbazole ring system. An X-ray structure of the di-tert-butyl derivative confirmed that both pyridyl groups were oriented for favorable intramolecular H-bonding to the central N-H. Two orientations of the molecule were found in the unit cell and this observation was corroborated by two N-H stretching bands in the solid state IR. Substitution of N-H by N-D led to increased emission intensity through diminished intramolecular deactivation of the excited state. The di-tert-butyl derivative formed a tridentate complex with Pd(II), which showed a red-shifted band attributed to an intraligand charge transfer state.
- Mudadu, Maria S.,Singh, Ajay N.,Thummel, Randolph P.
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p. 6513 - 6520
(2008/12/22)
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- Synthesis and isolation of nitro-β-carbolines obtained by nitration of commercial β-carboline alkaloids
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Nitration of commercial full aromatic β-carboline alkaloids nor-harmane (1), harmane (2), harmine (3), harmol (4), and the 7-acetylated derivative of harmol (5) is described. Advantages and disadvantages of different nitration reagents which involve acidic conditions (HNO3/H+) and neutral conditions (Cu(NO3)2; ceric ammonium nitrate) are discussed. A complete 1H and 13C-nmr characterization including ms and also uv absorption spectra in neutral and acid media is presented. A detailed ei-ms and ld-tof-ms study is enclosed because the nitro-β-carbolines constitute a new family of β-carboline-like chromophores with potential use as matrix in uv-maldi-tof-ms.
- Ponce,Erra-Balsells
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p. 1071 - 1082
(2007/10/03)
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- Lithiation of pivaloylamino derivatives of dibenzofuran and 9-methylcarbazole
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2-, 3- and 4-Pivaloylamino derivatives of dibenzofuran [compounds (5), (4) and (6), respectively] and analogous 3-, 2- and 1-substituted derivatives of 9-methylcarbazole [compounds (8), (7) and (9), respectively] were subjected to lithiation at 0°C and subsequent reaction with dimethylformamide. Aldehyde formation took place at positions α to δ to the heteroatom as follows: α for (4) and (7); δ for (5); δ and β (3 : 1) for (8); and α′ (6). No formylation occurred with (9).
- Deady,Sette
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p. 177 - 180
(2007/10/03)
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- A new method of nitration of carbazoles using ceric ammonium nitrate (CAN)
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A convenient procedure for the mononitration of carbazole and 9-alkylcarbazoles using CAN in CH3CN in presence of SiO2 is reported. The results with 9-acetyl, 9-benzoyl and 9- benzenesulphonylcarbazoles are also discussed.
- Chakrabarty,Batabyal
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- FLASH-VACUUM PYROLYSIS OF NITROARYLBENZOTRIAZOLES. A TANDEM MASS SPECTROMETRY STUDY
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Tandem mass spectrometry (MS/MS) has been applied to investigate the behaviour of 1-(2-nitrophenyl)benzotriazole upon flash-vacuum pyrolysis (FVP) conditions.Above 500 deg C, is pyrolyzed to give a mixture of 1-nitrocarbazole , 1-hydroxycarbazole and carbazole .Under similar conditions, 2-(2-nitrophenyl)benzotriazole appears to be more stable; it is however partially isomerized into 8 at high temperatures.Aza analogs of 8, like 1-(2-nitro-4-pyridyl)benzotriazole also loose nitrogen above 500 deg C to give a mixture of 1-nitro-3-azacarbazole , 1-hydroxy-3-azacarbazole and 3-azacarbazole .
- Maquestiau, Andre,Flammang-Barbieux, Monique,Flammang, Robert,Chen, Lin-Zhi
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p. 245 - 254
(2007/10/02)
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- Nitration of the Acetanilide-type Compounds
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Some aromatic compounds containing the imino group (NH) were nitrated in acetic acid or anhydride, and the ortho/para ratios were measured.N-Methyl derivatives of the aforementioned compounds are much less reactive when nitrated under comparable conditions and give significantly lower o/p ratios.These results along with the literature data support the hypothesis that the acetanilide-type compounds are nitrated via N-nitro intermediates.
- Daszkiewicz, Zdzislaw,Kyziol, Janusz B.
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- Photolysis of N-Nitrosodiphenylamines and N-Nitrosocarbazole
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N-Nitrosodiphenylamine, N-nitroso-2-nitrodiphenylamine and N-nitrosocarbazole on irradiation in benzene give products resulting from nitroso group migration.
- Sharma, K. S.,Kumari, Sharda,Goel, Vijender Kumar
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p. 435 - 436
(2007/10/02)
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- Nitration in the Carbazole Series, II
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9-Nitrocarbazole (1) was prepared and rearranged to give a mixture of 1-nitro- (2) and 3-nitrocarbazole (3) in the same ratio as observed in the case of the carbazole nitration.The evidence for the formation of 1 during the nitration of carbazole in acetic acid is given.The formation of C-nitro compounds during methylation of the 1,3,6,8-tetrachlorocarbazole/1,3,6,8-tetrachloro-9-nitrocarbazole complex can be explained by an alkali-catalysed nitramine rearrangement.The mechanism of this rearrangement is discussed.
- Kyziol, Janusz B.,Daszkiewicz, Zdislaw
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p. 1336 - 1345
(2007/10/02)
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- Synthesis and Properties of 3-Nitrosocarbazole
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The synthesis of 3-nitrosocarbazole (I) by the Fischer-Hepp rearrangement of 9-nitrosocarbazole has been described.The resistance of I to oxidation provides evidence that it cannot be the intermediate in the conversion of 9-nitrosocarbazole to the C-nitro compounds.It has also been shown that I and its derivatives cannot be synthesized by the action nitrosyl chloride on carbazoles.Methylation of I yields 9-methyl-3-nitrosocarbazole, 9,9'-dimethyl-3-azocarbazole and 9,9'-dimethyl-3-azoxycarbazole as the main products.The mechanism of this disproportionation process has been proposed.The spectral data of I are given.
- Kyziol, Janusz B.
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p. 1301 - 1305
(2007/10/02)
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- NITRATION IN THE CARBAZOLE SERIES
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Nitration of 9-tosylcarbazole in acetic anhydride solution gives 1-nitro (28percent), 2-nitro (19percent) and 3-nitro (53percent) derivatives.The mixture of the nitro compounds obtained from 9-acetylcarbazole contains 10percent, 48percent and 42percent of the isomers, respectively.Under similar conditions 9-nitrosocarbazole shows a different isomer distribution: 34percent of 1-nitro and 66percent of 3-nitrocarbazole.Nitration of carbazole is a two step process involving formation and rarrangement of 9-nitrocarbazole.The hypothesis was supported by the results of 1,3,6,8-tetrachlorocarbazole nitration and oxidation of 9-nitrosocarbazole and rearrengement of 9-nitrocarbazole in the nitration conditions.
- Kyziol, Janusz B.,Daszkiewicz, Zdzislaw
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p. 1857 - 1862
(2007/10/02)
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