- A new method for recycling asymmetric catalysts via formation of charge transfer complexes
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A new concept for recycling asymmetric bis(oxazoline)-type catalysts is reported. The formation of charge-transfer complexes between the chiral ligand and trinitrofluorenone and their subsequent precipitation and reuse by addition of new substrate solutions is described. The efficiency of this procedure is demonstrated in a Diels-Alder reaction to reach the expected endo product as major isomer (up to 97% de and 94% ee): the catalyst was used up to 12 times without loss of either activity or selectivity.
- Chollet, Guillaume,Rodriguez, Fernand,Schulz, Emmanuelle
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- Synthesis and reactions of trinitro-9,10-phenanthrenequinone derivatives
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The reaction of 2,4,7-trinitro-9,10-phenanthrenequinone with CuCl in aqueous dimethylformamide or dimethyl sulfoxide at room temperature, followed by acidification, gave a stable red complex of 2,4,7-trinitro-9,10- dihydroxyphenanthrene with a solvent molecule. On heating in a polar aprotic solvent in the presence of CuCl or other metal salt, 2,4,7-trinitro-9,10- phenanthrenequinone underwent benzilic acid rearrangement with formation of 2,4,7-trinitrofluorenone. The nitration of 9,10-sulfuryldioxyphenanthrene and subsequent decomposition of cyclic sulfates afforded previously unknown 1,3,6-trinitro- and 1,8-dinitro-9,10-phenanthrenequinones.
- Andrievskii,Linko,Grachev
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- Nitroaromatics as n-type organic semiconductors for field effect transistors
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The nitro group (NO2) is one of the most common electron-withdrawing groups but it has rarely been used in the design of organic semiconductors (OSCs). Herein, we report the n-type semiconducting behavior of simple fluorenone derivatives functionalized with NO2and CN groups. While the electron mobilities measured in the thin film field-effect transistors are modest (10?6-10?4cm2V?1s?1), the nitrofluorenone OSCs offer excellent air-stability and remarkable tunability of energy levelsviafacile modification of the substitution pattern. We study the effect of substituents on the electrochemical properties, molecular and crystal structure, and the charge transport properties of nitrofluorenones to revitalize the underestimated potential of NO2functionalization in organic electronics.
- Ghamari, Pegah,Hamzehpoor, Ehsan,Niazi, Muhammad Rizwan,Perepichka, Dmitrii F.,Perepichka, Igor F.
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- Fullerene acting as an electron donor in a donor-acceptor dyad to attain the long-lived charge-separated state by complexation with scandium ion
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A long-lived charge-separated (CS) state of fullerene-trinitrofluorenone linked dyad in which fullerene acts as an electron donor is formed by photoinduced electron transfer from C60 to TNF in the presence of Sc(OTf)3; the CS lifetime is determined as 23 ms in PhCN at 298 K. The Royal Society of Chemistry.
- Ohkubo, Kei,Ortiz, Javier,Martin-Gomis, Luis,Fernandez-Lazaro, Fernando,Sastre-Santos, Angela,Fukuzumi, Shunichi
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- A Charge-Transfer-Induced Self-Healing Supramolecular Hydrogel
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In this study, a dual-component charge-transfer (CT)-induced supramolecular hydrogel was fabricated using pyrene-tailored pyridinium (PYP) and 2,4,7-trinitrofluorenone (TNF) as the electron donor and acceptor, respectively. Its thermal stability and mechanical property have been modulated effectively by altering the concentration or molar ratio of PYP and TNF. Moreover, this CT hydrogel exhibited a distinct injectable self-healing property that could be utilized to create desired patterns on substrates. Such property holds potential for this CT hydrogel in fields like three-dimensional printing and surface coating.
- Gao, Lei,Gao, Yuxia,Lin, Yuan,Ju, Yong,Yang, Song,Hu, Jun
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- Improved, highly efficient, and green synthesis of bromofluorenones and nitrofluorenones in water
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A series of bromo-, nitro-, and bromonitrofluorenones were synthesized chemo-and regioselectively in 90-98% yield via electrophilic aromatic bromination and nitration under mild conditions using water as the sole solvent. These synthetic methods involve simple workup procedures and use only minimal amounts of organic solvents during the purification of products. The newly developed methods have the advantages of being cost-effective and environmentally friendly and could potentially be used for the large-scale synthesis of fluorenone derivatives. Copyright Taylor & Francis Group, LLC.
- Zhang, Xin,Han, Jun-Bin,Li, Peng-Fei,Ji, Xuan,Zhang, Zhao
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- Self-assembly of dendronized triphenylenes into helical pyramidal columns and chiral spheres
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The synthesis and structural and retrostructural analyses of a library containing 10 triphenylenes functionalized with self-assembling benzyl ether and phenyl propyl ether dendrons are reported. These dendronized triphenylenes adopt a crown rather than discotic conformation. Their crown conformation mediates the self-assembly of the discotic triphenylene unit in helical pyramidal columns and in chiral spheres. The chiral spheresare generated from short segments of helical pyramidal columns that are spherically distorted. Therefore, the chirality of the sphere is determ ined by a short helical pyramidal column that represents the inner part of the supramolecular sphere. Both the helical pyramidal columns and thechiral spheres represent supramolecular architectures that were self-as sembled for the first time from discotic molecules. The helical pyramidal columns self-organize in various hexagonal and rectangular lattices, while the chiral spheres self-organize into cubic and tetragonal periodicarrays and into a quasiperiodic 12-fold liquid quasicrystal. The helica l sense of the helical pyramidal columns and of helical spheres is selected by a stereocenter that can be incorporated either in the alkyl groups of the dendron or in the triphenylene part of the dendritic crown via donor-acceptor interactions. The self-assembly process of the dendronized triphenylene donor can be programmed by a new supramolecular "polymer effect" generated by donor-acceptor interactions.
- Percec, Virgil,Imam, Mohammad R.,Peterca, Mihai,Wilson, Daniela A.,Graf, Robert,et al.
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supporting information; experimental part
p. 7662 - 7677
(2009/10/17)
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- Indenoxadiazine, indenopyrazole and spiro triazole derivatives from (substituted ylidene)-N-phenylhydrazine carbothioamides
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In a multistep reaction, indeno[2,1-e][1,3,4]oxadiazine-9-one, oxoindeno[1,2-c]- pyrazolecarbothioamide, (thioxo-1,2,4-triazaspiro[4.5] decadienylidene)malononitrile and spiro-(fluorine-9,3′-[1,2,4]triazoline)- 5′-thione derivatives have been formed from a series of (substituted ylidene)-N-phenylhydrazinecarbothioamides 1a-e with (1,3-dioxo-2,3-dihydro-1H- inden-2-ylidene)propanedinitrile, 7,7′,8,8′-tetracyanoquinodimethane and (2,4,7-trinitro-9H-fluoren-9-ylidene)propanedinitrile in aerated pyridine. Rationales of these conversions involving the nucleophilic reactions, condensation, dehydrogenation and oxidation are presented.
- Hassan, Alaa A.,Shehata, Hamdy S.
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p. 629 - 635
(2008/09/19)
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- Reaction of 4-substituted thiosemicarbazides with (2,4,7-trinitro-9H- fluoren-9-ylidene)propanedinitrile
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4-Substituted thiosemicarbazides 4a-c reacted with (2,4,7-trinitro-9H- fluoren-9-ylidene)-propanedinitrile (2) in pyridine with admission of air to form spiro[fluorene-9,3'-(1,2,4-triazole)]derivatives 5a-c and (4-substituted thiosemicarbazono)propanedinitriles 6a-c in modest yields. 2,4,7-Trinitro-9- fluorenone (8) as well as one reduction product thereof and of 2, namely compounds 9 and 10, respectively are also found. A rationale for the conversions observed is presented.
- Hassan, Alaa A.,Ibrahim, Yusria R.,Shawky, Ahmed M.,Doepp, Dietrich
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p. 849 - 854
(2007/10/03)
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- Electrophotographic member
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Disclosed is an electrophotographic member containing as a charge transport material a fluorine-containing N,N,N',N'-tetraarylbenzidine derivative which is remarkably excellent in solubility in an organic solvent and/or a binder such as polycarbonate resin, etc., can show very excellent electrophotographic properties such as high sensitivity, low residual potential and high durability. Further, a fluorine-containing N,N,N',N'-tetraarylbenzidine derivative usable as a charge transport material, and a process for producing the same are disclosed. Furthermore, a fluorine-containing diarylamine usable for producing the fluorine-containing N,N,N',N'-tetraarylbenzidine derivative, and a process for producing the same are disclosed.
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- Electrophotographic recording medium containing τ and η metal-free phthalocyanine
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The disclosure is concerned with an electrophotographic recording medium having a layer of a photoconductive material containing at least one member selected from the group consisting of τ, τ', η, and/or η' form metal free phthalocyanine, the layer being formed on an electroconductive supporter. The recording medium of this invention is characterized in that the recording medium exhibits high sensitivity to longer wavelength light.
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