Carbazole chromophore

For some examples, see e.g. (a) Hogan CF, Harris AR, Bond AM et al (2006) Electrochemical studies of porphyrin-appended dendrimers. PhysChemChemPhys 8 2058-2065 (b) Jang W-D, Nishiyama N, Zhang G-D et al (2005) Supramolecular nanocarrier of anionic dendrimer porphyrins with cationic block copolymers modified with polyethylene glycol to enhance intracellular photodynamic efficacy. Angew Chem Int Ed 44 419 -23 (c) Loiseau F, Campagna S, Hameurlaine A et al (2005) Dendrimers made of porphyrin cores and carbazole chromophores as peripheral units. Absorption spectra, luminescence properties, and oxidation... 

All of the chrestifoline alkaloids have a UV spectrum characteristic of a carbazole chromophore. The H-NMR spectra of all these alkaloids showed signals for an NH proton at b 10.16 or 10.31, an aromatic methoxy group at b 3.84 or 3.85, and a 2H singlet at b 4.78-5.80 assigned to the benzylic methylene protons connected to... 

The absorption spectrum of a carbazole-acceptor cyclophane shows transannular 7t-7t electronic interaction and little charge transfer interaction, while the fluorescence spectrum exhibits intramolecular exciplex emission around 525 nm <2003CL910>. 6,13-Bis(9-ethyl-9//-carbazol-3-yl)pentacene (a pentacene derivative bearing two carbazole moieties) displays an absorption spectrum that consists of the bands due to the carbazole (352 nm) and the pentacene moieties (483, 523, 561, 605 nm), indicating that the electronic transition level of pentacene is not affected by the carbazole chromophore <2006MI185>. 

In PVK, hole transport occurs by hopping between adjacent carbazole chromophores pendant to the main hydrocarbon chain. The main chain exerts a secondary influence. 

Two similar systems with carbazole donor chromophores and porphyrin core acceptors were reported by the groups of Dehaen [78] and Lu [79]. With varying linker architecture and branching methods, Dehaen s system included dendrimers with 4, 8, and 12 carbazole chromophores per porphyrin core (Scheme 27). Lu s system also included materials with 4, 8, and 12 carbazole chromophores per porphyrin core, but with a different branching architecture (Scheme 27). The absorption spectra of the dendrimers in both of these studies are additive, with the visible transitions of the porphyrin cores. 

Charge transfer complexation occurs in a similar manner in poly(2-carbazolylethyl acrylate) molecularly doped with 2,4,7-trinitrofluorene. Quantum efficiency of the hole propagation of the copolymer with the 0.05-1.0 molar ratio of trinitrofluorene to carbazole chromophores is higher than in the corresponding trinitrofluorene and ethyltrinitrofluorene doped homopolymer of poly(2-carbazolylethyl acrylate) [251]. 

Hui, C. Xiaohui, T. Yizhong, Y. Jiaping, L., Preparation of Polysiloxane with Pendant Cr-Bound Carbazole Chromophore for Non-Linear Optics. J. Appl. Polym. Sci. 2008,107,4076-4081. 

Other side chains include unusually long n-alkyl groups, - cyclics (cy-clolinear carbosiloxanes), fluorocarbons, phenylethenyl substituents, Cr-bound carbazole chromophores, and pendant bicyclic fragments. ... 

Henceforth, the synthesis of multifunctional methaciylic copolymers with side-chains chiral moieties linked to a photochromic azoaromatic and to photo-conductive carbazolic chromophores based novel optically active polymers are very meaningful. 

Loiseau F, Campagna S, Hameurlaine A, Dehaen W (2005) Dendrimers made of porph)nin cores and carbazole chromophores as peripheral units. Absorption spectra, luminescence properties, and oxidation behavior. J Am Chem Soc 127(32) 11352-11363... 

Figure 9.13 Total absorption coefficient of single crystalline DCH (a carbazole-substituted polydiacetylene) obtained by Kramers-Kronig analysis of 8 K reflection data. The broken portion reflects transitions of the carbazole chromophore. is the profile of the transition leading to charge carrier formation, cn, refers to the exciton transition. The broken portion of the Ot curve reflects sensitized carrier generation via side-group excitation. Eg is the band gap inferred from electroabsorption work (see Reference 4). (From Bassler, H., in Polydiacetylenes, Bloor, D. and Chance, R. R., Eds., M. Nijhoff, Dordrecht, 1985, 135. With permission.)...

TABLE 1. Conversion efficiency of carbazole chromophore into ionized one... 

This indicates that the interaction of the two carbazole chromophores in the partial overlap excimer is weak, and that the interaction of the two carbazole chromophores in the full overlap excimer is strong. 

Electronic transitions of the carbazole chromophores afford a highly sensitive probe for studies of carbazole-containing polymers in respect of their absorption and emission characteristics as well as of either inherent or induced circular dichroism. They have been conveniently employed to describe microstructural characteristics of carbazole-containing polymers, including homopolymers of carbazolated a-aminoacids and of vinylated carbazoles with chiral substituents. Data obtained are entirely consistent with interpretation of polymer structures derived from related UV absorption, excimer fluorescence emission and NMR studies and are especially valuable as a completely new indication of copolymer sequence distributions. 

The negative influence of excimer formation has to be taken into consideration for the molecular design of new polymers having high carrier generation efficiency and effective carrier transport. Ledwith et al. have concluded that carbazole-containing polymers do not exhibit excimer emission except when the carbazole chromophores are directly bound to the polymer backbone [61]. This conclusion was corroborated by the investigation of the photophysical properties of dilute solutions of a number of polymers [62-64]. 

Polymers interesting from the points of view of both non-linear optics and photoconductivity have been prepared by Wada and co-workers [223,224]. They have synthesized a series of head-to-tail polymers with dipolar carbazole chromophores [223]. The structures... 

The fluorescence and phosphorescence emissions of the carbazole chromophore are completely quenched by the nitro or cyano derivatives of fluorene. The mechanism of quenching is explained by two fast intramolecular photoprocesses electron transfer and/or energy transfer. The evaluation of the photoactivity of oligomers (37a) and (37b) has revealed that (37b) is more photoactive than (37a) due, mainly, to a better orbital overlap between the donor and acceptor moieties in oligomer (37b) compared with oligomer (37a). Furthermore, a comparison of the polysebacate oligomers (37) with a standard PVK-TNF system has shown that the latter is much more photoactive due, again, to a better orbital overlap. The poor photoconductive... 

Zhang Y, Wang L, Wada T, Sasabe H (1996) One-pot synthesis of a new hyperbranched polyester containing 3,6-di-acceptor-substituted carbazole chromophores for nonlinear optics. Macromol Chem Phys 197 667-676... 

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