Synthesis carbazole groups

Y. Fu, J. Li, S. Yan, and Z. Bo, High molecular weight dendronized poly(fluorene)s with peripheral carbazole groups synthesis, characterization, and properties, Macromolecules, 37 6395-6400, 2004. 

Copolymers having the carbazole group and the oxadiazole group directly in the backbone, i.e., poly[3,6-A-Ethylcarbazole-l,3,4-oxadiaz-ole-2,5-diyl], can be prepared from A-ethylcarbazole-3,6-dicarboxylic acid and hydrazine hydrochloride.The reaction runs at 140°C with PPA. The synthesis is shown in Figure 10.4. 

The synthesis of a series of polyacrylates and methacrylates with pendant carbazole groups has been reported [587]. The polymers were prepared by the reaction of ffl-hydroxyalkylcarbazoles or the corresponding alkoholates with poly(acryloyl chloride) and poly(methacryloyl chloride) (43). GPC, H-NMR, and elemental analysis show that high-molecular weight polymers with an almost quantitative degree of substitution are obtained by this polymer analogous reaction. 

Since the discovery of photoconductivity in poly(N-vinylcarbazole) (PVK) [1,2] a variety of polymers with carbazole groups have been synthesized and their photophysical properties have been investigated. The main topic of this article is the synthesis of photoconductive polymers, so minor attention is given to their photophysical properties. PVK (2b) can be synthesized by free-radical, cationic, or charge-transfer initiated polymerization of N-vinylcarbazole (2a). A detailed description of the PVK synthesis is given in Chapter 2 of this handbook. 

Gratt J, Cohen RE (1997) Synthesis of block copolymers containing pendant carbazole groups via living ring-opening metathesis polymerization. Macromolecules 30 3137-3140... 

Accordingly for almost a decade the authors have studied, in a systematic way, the synthesis and properties of optically active polymers containing carbazole groups . In the present paper they review and evaluate the relevance of such studies to the interpretation of structural and electronic properties. 

Several poly(a-amino acids) with pendant carbazole groups have been described. Tanikawa et al. [193] reported on the synthesis of poly(y-2-(V-carbazolyl)-ethyl-L-glutamate) (18a) and discussed the photoconductivity of the polymer and its charge-transfer complex with TNF. The photocurrents in (18a) are about one order of magnitude smaller than in PVK at all measured wavelengths. Poly(5 -2-(V-carbazoly-l)ethyl-L-cysteine) [194,195] (18b) a jS-sheet forming polypeptide, was synthesized from the corresponding V-carboxy anhydride. 

Polymers with pendant carbazole groups described in this section are usually prepared either by addition polymerization (most frequently free-radical) or by polymeranalogous reactions. Ogava et al. [216] have reported on the synthesis of a carbazolyl-substituted polymer by polycondensation. By condensing a carbazole-containing bisphenol with phosgene they... 

Rovkina et al. [222,280] reported on the synthesis of oligoesters having pendant carbazole groups. They were prepared by polycondensation of EPK (32a) or 3-(9-carbazolyl)propane-diol-l,2 (34a) with dicarboxylic acids (adipic, sebacic or phthalic). The carbazole-containing oligoesters had relative molecular masses from 640 to 2640 and exhibited photoconductivity and good film-forming properties. 

In synthesis of the alkaloid tjipanazole E (19b), the required symmetric dichloro-indolo[2,3-fl]carbazole 20a was obtained in a two-step procedure starting fi-om 4-chlorophenylhydrazine hydrochloride and 1,2-cyclohexanedione employing a Fischer indolization. Subsequent attachment of an acetyl-protected glucopyranosyl moiety to one of the nitrogens, followed by cleavage of the protective groups with ammonia in methanol, produced the desired natural product (91X7739). 

Applying these methodologies monomers such as isobutylene, vinyl ethers, styrene and styrenic derivatives, oxazolines, N-vinyl carbazole, etc. can be efficiently polymerized leading to well-defined structures. Compared to anionic polymerization cationic polymerization requires less demanding experimental conditions and can be applied at room temperature or higher in many cases, and a wide variety of monomers with pendant functional groups can be used. Despite the recent developments in cationic polymerization the method cannot be used with the same success for the synthesis of well-defined complex copolymeric architectures. 

In the effort to make pure blue-emitting materials Shim and coworkers [146] synthesized a series of PPV-based copolymers containing carbazole (polymers 95 and 96) and fluorene (polymers 97 and 98) units via Wittig polycondensation. The use of trimethylsilyl substituents, instead of alkoxy groups, eliminates the electron donor influence of the latter and leads to chain distortion that bathochromically shifts the emission (Amax = 480 nm for 95 and 495 nm for 97). In addition, a very high PLQY was found for these polymers in the solid state (64 and 81%, respectively). Single-layer PLEDs fabricated with 95 and 97 (ITO/polymer/Al) showed EL efficiencies of 13 and 32 times higher than MEH-PPV, respectively (see also Ref. [147] for synthesis and PLED studies of polymers 99 and 100) (Chart 2.20). 

The formation of carbon-carbon bonds by palladium-promoted reactions has been widely used in organic synthesis [114-116]. A major advantage is that most of these coupling reactions can be performed with catalytic amounts of palladium. Palladium(II)-catalyzed reactions, e.g., the Wacker process, are distinguished from palladium(O)-catalyzed reactions, e.g., the Heck reaction, since they require oxidative regeneration of the catalytically active palladium(II) species in a separate step [117]. Several groups have applied palladium-mediated and -catalyzed coupling reactions to the construction of the carbazole framework. 

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