Carbazole-containing

Similar PPV-based copolymers with carbazole and fluorene units in the backbone 101 and 102 (and also similar copolymers with oxadiazole substituents 103 and 104) have been synthesized by Ree and coworkers [148], Much lower PL efficiency in films was found in this case for carbazole-containing polymers 102 and 104 (1-4%), when compared to materials prepared by Shim (95 and 96, 59-64%) (Chart 2.21). 

Blends of yellowish-green-light emissive carbazole-containing PPV-based copolymer 105 (Apl = 490, 520 nm, AEL = 533 nm) with blue-emissive oxadiazole- poly-/ -phenylene (PPP) copolymer 106 (AEL = 426 nm) allowed to tune the emission of PLEDs (ITO/polymer blend/Al) from AEL = 533 nm to AEL = 451 nm, although the device turn-on voltage was essentially higher for the blends with increased content of 106 [149] (Chart 2.22). 

J.V. Grazulevicius, P. Strohriegl, J. Pielichowski, and K. Pielichowski, Carbazole-containing polymers synthesis, properties and applications, Prog. Polym. Sci., 29 1297-1353, 2003. 

Vetrichelvan M, Nagarajan R, Vahyaveettil S. Carbazole-containing conjugated copolymers as colorimetric/fluorimetric sensor for iodide anion. Mactomolecules 2006 39 8303-8310. 

Recent developments in the total syntheses and structural modifications of the natural carbazole-containing ellipti-cine alkaloids and related indolocarbazoles were the subject of a review <2001COR507>. Modifications designed to effect changes in biological activities were emphasized. 

Donor-Acceptor Complexes of Carbazole-Containing Polymers... 

Intrinsically carbazole containing polymers are photosensitive in the UV range of spectra. The applications of such polymers in electrophotography and related processes need sensitization to the visual wavelengths. The most acceptable method is charge transfer formation between polymer donor and acceptor molecules. Hoegl pointed out that 0.1-2% of acceptor molecules inserted in the polymer matrix lead to a substantial increase in the photoconductivity especially in the CT bands. Subsequently, a lot of paper were published for CT-carbazole-containing complexes and such materials were used in photosensitive processes. Various types of molecules were used as a photosensitizers. 

Carbazole-containing PODs have been obtained (53) by cyclodehydration (in the presence of POCl3) of polyhydrazides prepared by polycondensation of IV-ethyl-3,6-carbaZoledicarbonyl chloride with dihydrazides of the corresponding dicarboxylic acids. Thermal decomposition of the polymers containing aliphatic units occurs at 365-380°C, compared to 400-405°C for polymers containing aromatic units. 

Subsequently, Cao et al. incorpated electron and hole transporting groups on to the zinc(II) Schiff base polymer chain for PLEDs application (Fig. 21).35 Fluorene and carbazole-containing polymers were prepared by reacting the... 

Chigwada, G., Jiang, D. D., and Wilkie, C. A. Polystyrene nanocomposites based on carbazole-containing surfactants, Thermochimica Acta (2005), 436, 13-121. 

Carbazole-containing stilbene analogues have been shown to be efficient two-photon absorbing chromophores <2000TL8573>. 

The following photoconductive polymers can also be clarified as polymers of aromatic amines poly(N-vinylphenothiazine) and poly(N-vinylphenoxazine ° and poly(N-acrylodibenzazepine) ° Poly(N-vinylcarbazole) is basically a modified vinyldiphenylamine polymer . It has yet to be detemined if the transport characteristics of PVK with the diphenyl amino group forced into planarity are different from those of poly(N-vinyldiphenylamine) which would possess a greater freedom of rotation. The properties of PVK have been discussed in many articles and reviews [for example see Ref. ]. Several articles and patents have been published recently which deal with carbazole containing polymers other than PVK, and copolymers of N-vinylcarbazole with some other monomers. 

Aniline, indole, and carbazole contain nitrogen bonding in their chemical structure. Tables 1-3 show where to these model compounds belong. 

Almost aU of the pyrrole-, indole-, and carbazole-containing systems afforded stable Fe(ll) and Co(II) complexes. The only exceptions are hgands 44 and 47 which contain only aryl substituents. This indicates that two pairs of o-phenyl groups on the N-pyrrolyl substituents impose too much of a steric hindrance and/ or are too electron-withdrawing for the corresponding [N,N,N] metal complex to form. The two Fe(lII) precatalysts 54c, 55c were synthesized to evaluate the dependence of the polymerization performance on the oxidation state of the metal center. In total, twenty-one different N-azolyl complexes were prepared aiming at a thorough structure-activity evaluation (vide infra). 

Very little has been published on the full assignment of protons in carbazole-containing systems because of the difficulties in full assignment of the often overlapping signals. The basic chemical shifts are as follows 1-H (8-H) 7.49 ppm 2-H (7-H) 7.36 ppm 3-H (6-H) 7.16 ppm 4-H (5-H) 8.08... 

Carbon-13 NMR has established itself as an indispensable tool for structure determination in the area of carbazole-containing natural products, and the reader is encouraged to consult the articles by Chakraborty <87FORi59, 9lFOR7l> for a more exhaustive treatment of carbazole alkaloids. A shorter overview of the typical C resonances for carbazoles is included in Table 24. 

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