- A new and efficient pyridine-2,6-dicarboxamide-based fluorescent and colorimetric chemosensor for sensitive and selective recognition of Pb2+ and Cu2+
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A new fluorene-bearing pyridine-2,6-dicarboxamide (3) as an effectint fluorescent and colorimetric cation sensor was successfully synthesized and well-characterized using FT-IR, NMR, ESI+-MS and elemental analysis. The metal ion binding ability of the chemosensor 3 in the presence of different metal ions was investigated using UV–vis, fluorescence experiments and results exhibited a desirable selectivity and significant sensitivity of the chemosensor 3 for the detection of Cu2+ and Pb2+ ions. The association constant (Ka) of 3-Cu2+ and 3-Pb2+ complexes were determined to be 8.89 × 103 M?1 and 5.65 × 108 M-2, respectively. The obtained limit of detection (LOD) values (1.49 × 10?6 M for Cu2+ and 2.31 × 10?6 M for Pb2+) clearly revealed the considerable sensitivity of the chemosensor 3.
- Hosseinzadeh, Rahman,Rahimi, Hannaneh,Tajbakhsh, Mahmood
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- Microwave-induced surface-mediated highly efficient regioselective nitration of aromatic compounds: Effects of penetration depth
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Surface mediated highly regioselective nitration of aromatic compounds under diverse microwave-induced conditions was investigated in this work. The effects of the penetration depth of the surfaces were found to be more crucial than other dielectric parameters. Despite significant progress of microwave-induced reactions, no reports have examined the penetration depth of the surfaces used in these processes.
- BANIK, BIMAL K.,DAS, APARNA,YADAV, RAM NARESH
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p. 2203 - 2206
(2021/08/24)
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- A new fluorene-based Schiff-base as fluorescent chemosensor for selective detection of Cr3?+ and Al3?+
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2-((9H-fluoren-2-ylimino) methyl)phenol (F3) was synthesized by condensation reaction of 9H-fluoren-2-amine and 2-hydroxybenzaldehyde in EtOH and characterized by its melting point, 1H-,13C NMR and molecular mass. F3 exhibits a high selectivity for detection of Cr3?+ and Al3?+ ions as a fluorescent chemosensor and showed a single emission band at 536?nm upon excitation at 333?nm according to fluorescence emission studies. The addition of Cr3?+ and Al3?+ make a significant increase in fluorescent intensity at 536?nm in CH3CN, while other metal ions have almost no influence on the fluorescence. The fluorescence enhancement was attributed to the inhibited C[dbnd]N isomerization and the obstructed excited state intra-molecular proton transfer (ESIPT) of compound F3. Job's plot and DFT calculations data showed that the binding stoichiometries of F3 with Cr3?+ and Al3?+ are 2:1. The association constants (Ka) for Cr3?+ and Al3?+ were calculated and found to be 8.33?×?104?M??1 and 5.44?×?104?M??1, respectively. The detection limits were also calculated for Cr3?+ and Al3?+ and found to be 2.5?×?10??7?mol/L and 3.1?×?10??7?mol/L, respectively.
- Tajbakhsh, Mahmood,Chalmardi, Gholam Babaei,Bekhradnia, Ahmadreza,Hosseinzadeh, Rahman,Hasani, Nahid,Amiri, Mohammadreza Azizi
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- Comparative analysis to explore the suitability of a short chain dyad in its pristine and nanocomposite forms for designing artificial light energy conversion device
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From the UV-vis, steady state and time resolved spectroscopic investigations on the pristine dyad, dyad-spherical gold nanoparticles (GNP) and dyad-star shaped gold nanoparticles (GNS), it was observed that though in the ground state the dyad in its pristine form possesses trans-type (elongated and planar) isomer but on photoexcitation trans-form converts into cis-structure (folded). Interestingly, the dyad exhibits different behavior when it combines with GNP or GNS. In nanocomposite form, even on photoexcitation some ground state trans-structure still retains its identity in the excited state. The 60% of the trans-species remains unchanged in the excited state due to excitation of dyad-GNS system and possibly this configuration facilitates the hindrance of energy destructive charge recombination processes as in this conformer the donor and acceptor moieties tend to move far away from each other causing lack of overlapping of charge clouds within the two redox components. The dyad-GNS nanocomposite appears to be the best possible light energy conversion or storage device within the three system studied in the present investigation. Investigations are underway to examine how the degree of surface coverage of the dyad on the surface of gold nanoparticles affect its geometry or conformational changes on photoexcitation.
- Paul, Somnath,Mitra, Ishani,Dutta, Rituparna,Bardhan, Munmun,Bose, Mridul,Das, Subrata,Saha, Mithu,Ganguly, Tapan
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p. 7873 - 7881
(2018/09/06)
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- Aromatic azoxybenzene compound and preparation method thereof
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The invention discloses an aromatic azoxybenzene compound and a preparation method thereof. The preparation method comprises the following steps: firstly reducing aromatic nitro-compounds into azoxybenzene through photoinduction in an alkaline condition; firstly synthesizing different aromatic nitro-compounds; secondly, carrying out nitro reduction under the irradiation of a xenon lamp under the conditions of potassium hydroxide, methylbenzene and isopropyl alcohol, and thus synthesizing the aromatic azoxybenzene compound. The preparation method disclosed by the invention has the advantages of simple components, mild reaction conditions, low toxicity, environmental protection, high selectivity and the like; the obtained aromatic azoxybenzene compound has potential application in the aspects of dyes, liquid crystal materials, optical materials and the like.
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Paragraph 0018; 0027
(2017/10/25)
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- Amidofluorene-appended lower rim 1,3-diconjugate of calix[4]arene: Synthesis, characterization and highly selective sensor for Cu2+
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Functionalization of calix[4]arene with amidofluorene moieties at the lower rim led to formation of the 1,3-diconjugate of calix[4]arene L as a novel fluorescent chemosensor for Cu2+. The receptor molecule L exhibited a pronounced selectivity towards Cu2+ over other mono and divalent ions. The formation of the complex between L and Cu2+ was evaluated by absorption, fluorescence and 1H NMR spectroscopy. The sensor L showed a remarkable color change from colorless to purple and a fluorescence quenching only upon interaction with Cu2+. The 1:1 stoichiometry of the obtained complex has been determined by Job's plot. The association constant determined by fluorescence titration was found to be 1.8 × 106 M-1. The sensor showed a linear response toward Cu2+ in the concentration range from 1 to 10 μM with a detection limit of 9.6 × 10-8 M.
- Hosseinzadeh, Rahman,Nemati, Mohammad,Zadmard, Reza,Mohadjerani, Maryam
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p. 1749 - 1757
(2016/10/05)
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- Fluorene-morpholine-based organic nanoparticles: Lysosome-targeted pH-triggered two-photon photodynamic therapy with fluorescence switch on-off
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Nanocarrier-mediated photodynamic therapy (PDT) is an effective tool for anti-tumour treatment due to the targeted and image-guided delivery of photosensitizers (PSs) to diseased tissues. These nanocarriers range from inorganic, ceramic, polymeric to biological nanoparticles (NPs). Such PS-grafted bicomponent nanocarriers have limitations like (i) difficulty in surface modification, (ii) lower loading percentages of the therapeutic agent, (iii) unstable physical encapsulation, etc. By any means, if we can prepare PSs directly as NPs then we can surpass the above drawbacks. Hence, we synthesised new two-photon fluorene-functionalised morpholine (Fluo-Mor)-based organic NPs that showed strong fluorescence and profound photodynamic therapy (PDT) activity only in acidic medium. Such a pH-responsive appearance of fluorescence enables Fluo-Mor NPs for the real time monitoring of photodynamic therapeutic activity selectively in low-pH organelles viz. lysosome. Cytotoxicity of Fluo-Mor NPs was monitored using time-dependent and dose-dependent cancer cell viability assay and confocal imaging.
- Gangopadhyay, Moumita,Mukhopadhyay, Sourav K.,Gayathri, Sree,Biswas, Sandipan,Barman, Shrabani,Dey, Satyahari,Singh, N. D. Pradeep
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supporting information
p. 1862 - 1868
(2016/03/12)
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- Platinum(II) complexes bearing 2-(9,9-dihexadecyl-7-R-fluoren-2-yl)-1,10- phenanthroline ligands: Synthesis, photophysics and reverse saturable absorption
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Six platinum(II) complexes bearing 2-(9,9-dihexadecyl-7-R-fluoren-2-yl)-1, 10-phenanthroline ligands (R = NO2, CN, I, H, benzothiazole, thiophene for ligands 1-6, respectively) were synthesized and their photophysics and reverse saturable absorption (RSA) were systematically investigated. All complexes exhibit intense absorption bands between 350 and 450 nm, which are attributed to 1π,π/1ILCT (intraligand charge transfer) transitions, and broad 1MLCT (metal to ligand charge transfer) transitions between 475 and 550 nm. All complexes are emissive at room temperature in a variety of solvents and at 77 K in butyronitrile glassy matrix, with the long-lived, structured emission appearing between 600 and 750 nm. The emitting states are assigned to predominantly the 3π, π* state with an admixture of 3MLCT characters. Upon ns laser excitation at 355 nm, all complexes display broad, moderately strong transient absorption from the visible to the near-IR region. As a result, RSA is observed from all complexes at 532 nm for ns laser pulses. The strength of the RSA for these complexes follows the trend: Pt-2 > Pt-3 > Pt-4 > Pt-1 >> Pt-5 > Pt-6, which correlates well with the trend of the estimated ΦTσex/σ0 values (where ΦT is the triplet excited state quantum yield, and σex and σ0 are the excited-state and ground-state absorption cross-section, respectively) at 532 nm. It is revealed that substitution at the 7-position of the fluorenyl component exerts a distinct effect on the photophysics and RSA of the complexes. Aromatic substituents such as benzothiazol-2-yl and 2-thionyl cause pronounced red-shifts of the absorption bands, the emission bands, and the transient difference absorption bands, but a decrease of the RSA at 532 nm. Platinum(II) complexes bearing 2-(9,9-dihexadecyl-7-R-fluoren-2-yl)-1,10-phenanthroline ligands exhibit a long-lived, broadband-absorbing excited state and strong reverse saturable absorption (RSA) at 532 nm for ns laser pulses. The substituent at the 7-position of the fluorenyl component exerts a pronounced effect on both the photophysical properties and the RSA. Copyright
- Liu, Xu-Guang,Sun, Wenfang
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supporting information
p. 4732 - 4742
(2013/09/24)
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- Variation of the backbone conjugation in NLO model compounds: Torsion-angle-restricted, biphenyl-based push-pull-systems
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Terminal piperidinyl- and nitro-functionalized biphenyls, bridged between the 2 and. 2′ positions by a variable number of methylene groups, are synthesized and fully characterized. These push-pull systems with defined and restricted torsion angles between their phenyl rings are ideal model compounds to investigate the influence of the chromophore's conjugation in nonlinear optic (NLO) responses, A general synthetic route that can be implemented to access these model compounds is reported, starting from dibromo or ditriflate biphenyls. Hartwig-Buchwald cross-coupling, a selective azacycloalkylation of diaminobiphenyls and a mild oxidation of primary amines to nitro groups in the presence of a tertiary amine summarizes the synthetic pathway towards the desired model compounds. NLO properties of the series of torsionally constrained push-pull biphenyls are collected by electric-field-induced second-harmonic generation (EFISH) experiments. The results agree qualitatively with semi-empirical simulations based on the AM1 Hamiltonian. A. linear dependence of the quadratic response on the cos2(o) of the inter-aryl dihedral angle is observed, which points to oscillator strength loss as the dominant effect of increasing backbone twist
- Rotzler, Juergen,Vonlanthen, David,Barsella, Alberto,Boeglin, Alex,Fort, Alain,Mayor, Marcel
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scheme or table
p. 1096 - 1110
(2010/04/27)
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- Selective oxidation of aromatic amines to nitro derivatives using potassium iodide-tert-butyl hydroperoxide catalytic system
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The direct oxidation of aromatic primary amines to the corresponding nitro compounds selectively in 47-98% yields has been achieved by using potassium iodide as catalyst and tert-butyl hydroperoxide as the external oxidant. The present catalytic system works well for both electron-rich and electron-poor substrates.
- Reddy, K. Rajender,Maheswari, C. Uma,Venkateshwar,Kantam, M. Lakshmi
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supporting information; experimental part
p. 93 - 96
(2009/08/07)
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- White-light emitting hydrogen-bonded supramolecular copolymers based on #-conjugated oligomers
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Three different ?-conjugated oligomers (a blue-emitting oligofluorene, a green-emitting oligo(phenylene vinylene), and a red-emitting perylene bisimide) have been functionalized with self-complementary quadruple hydrogen bonding ureidopyrimidinone (UPy) units at both ends. The molecules self-assemble in solution and in the bulk, forming supramolecular polymers. When mixed together in solution, random noncovalent copolymers are formed that contain all three types of chromophores, resulting in energy transfer upon excitation of the oligofluorene energy donor. At a certain mixing ratio, a white emissive supramolecular polymer can be created in solution. In contrast to their unfunctionalized counterparts, bis-UPy-chromophores can easily be deposited as smooth thin films on surfaces by spin coating. No phase separation is observed in these films, and energy transfer is much more efficient than in solution, giving rise to white fluorescence at much lower ratios of energy acceptor to donor. Light emitting diodes based on these supramolecular polymers have been prepared from all three types of pure materials, yielding blue, green, and red devices, respectively. At appropriate mixing ratios of these three compounds, white electroluminescence is observed. This approach yields a toolbox of molecules that can be easily used to construct ?-conjugated supramolecular polymers with a variety of compositions, high solution viscosities, and tuneable emission colors.
- Abbel, Robert,Grenier, Christophe,Pouderoijen, Maarten J.,Stouwdam, Jan W.,Leclere, Philippe E. L. G.,Sijbesma, Rint P.,Meijer, E. W.,Schenning, Albertus P. H. J.
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supporting information; scheme or table
p. 833 - 843
(2009/07/01)
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- A new thermo- and photo-driven [2]rotaxane
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A new rotaxane with functional chromophores porphyrin and fluorene as stoppers has been synthesized. It displays dual fluorescent character. The macrocycle ring can shuttle between the fumaramide part and the succinimide part on the dumbbell. Heating and UV light irradiating on the rotaxane lead to the reversible E/Z conversion, driving the ring to shuttle between the two stations. The optical properties of porphyrin and fluorene stoppers of the thread do not change so much while the ring shuttles because the macrocycle does not interact with the two stoppers. However, the active group, propargyloxyl, is introduced onto the two sides of the ring so that the rotaxane has the potential to be functionalized by further decoration.
- Ji, Feng-Yuan,Zhu, Liang-Liang,Ma, Xiang,Wang, Qiao-Chun,Tian, He
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supporting information; experimental part
p. 597 - 600
(2009/05/27)
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- Selective nitration of aromatic compounds with bismuth subnitrate and thionyl chloride
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Bismuth subnitrate/thionyl chloride have been found to be an efficient combination of reagents for nitration of a wide range of aromatic compounds in dichloromethane. Phenols, in particular, were easily mononitrated and dinitrated with the reagents by controlling the stoichiometry.
- Muathen, Hussni A.
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p. 593 - 598
(2007/10/03)
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- Surface-mediated highly efficient regioselective nitration of aromatic compounds by bismuth nitrate
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Montmorillonite impregnated with bismuth nitrate was found to be an excellent reagent for aromatic nitration in high yield. (C) 2000 Elsevier Science Ltd.
- Samajdar,Becker,Banik
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p. 8017 - 8020
(2007/10/03)
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- Synthesis of new two-photon absorbing fluorene derivatives via Cu-mediated Ullmann condensations
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The Ullmann amination reaction was utilized to provide access to a number of fluorene analogues from common intermediates, via facile functionalization at positions 2, 7, and 9 of the fluorene ring. Through variation of amine or iodofluorene derivative, analogues bearing substitutents with varying electron-donating and electron-withdrawing ability, e.g., diphenylamino, bis-(4-methoxyphenyl)amine, nitro, and benzothiazole, were synthesized in good yield. The novel fluorene derivatives were fully characterized, including absorption and emission spectra. Didecylation at the 9-position afforded remarkably soluble derivatives. Target compounds 4, 5, and 9 are potentially useful as fluorophores in two-photon fluorescence microscopy. Their UV-vis spectra display desirable absorption in the range of interest suitable for two-photon excitation by near-IR femtosecond lasers. Preliminary measurements of two-photon absorption indicate the derivatives exhibit high two-photon absorptivity, affirming their potential as two-photon fluorophores. For example, using a 1210 nm femtosecond pump beam, diphenylaminobenzothiazolylfluorene 4 exhibited nondegenerate two-photon absorption, with two-photon absorptivity (δ) of ca. 820 x 10-50 cm4 s photon-1 molecule-1 at the femtosecond white light continuum probe wavelength of 615 nm.
- Belfield, Kevin D.,Schafer, Katherine J.,Mourad, Wael,Reinhardt, Bruce A.
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p. 4475 - 4481
(2007/10/03)
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- Nitration of polycyclic aromatic hydrocarbons using a supported catalyst
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We report the use of a catalyst, sulfuric acid supported on silica-gel, as a promising method for facile, high yielding, regioselective syntheses of mononitrated polycyclic aromatic hydrocarbons, 6-nitrochrysene, 1- nitropyrene, 1-nitronaphthalene, 2-nitrofluorene, 3-nitrofluoranthene, and 9- nitroanthracene.
- Smith, Amy C.,Narvaez, Lorena D.,Akins, Bridget G.,Langford, Moses M.,Gary, Thomas,Geisler, Victoria J.,Khan, Farooq A.
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p. 4187 - 4192
(2007/10/03)
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- Characterization of 9-(p-Substituted Benzylidenehydrazono)fluorenes
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The title azine was obtained by a reaction of the corresponding fluorenone hydrazone and p-substituted benzaldehyde. The hydrazone formed from the unsymmetrical fluorenone afforded configurational isomers; the E-isomer was thermodynamically more stable than the Z-isomer. The structure of the title azines, derived from symmetrical fluorenone, was assigned to be (s-translE) form. The azines from unsymmetrical fluorenone gave isomeric mixtures due to the 9-iminofluorene moiety. The electronic spectra of these azines show an intramolecular charge transfer; the red shift beyond 250 nm is observed in the case of 9-[p-(diethylamino)benzylidenehydrazono]-2,4,7-trinitrofluorene, compared to the mother azine. 9-[p-(Pentyloxy)benzylidenehydrazono]-2,7-dinitrofluorene and some of the homologs possess a liquid-crystalline property; the phase-transition temperature of the dinitro compound is K (172 °C) M1 (185)M2 (187) I between the crystalline and liquid phases.
- Minabe, Masahiro,Takabayashi, Yutaka,Setta, Yuji,Nakamura, Hidenao,Kimura, Takao,Tsubota, Motohiro
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p. 3633 - 3638
(2007/10/03)
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- Orbital distortion arising from remote substituents. Nitration, reduction, and epoxidation of fluorenes bearing a carbonyl or an olefin group in spiro geometry
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Nitration of spiro[cyclopentane-1,9′-fluoren]-2-one with acetyl nitrate predominantly gave the 4-nitro derivative. In the reduction of substituted spiro[cyclopntane-1,9′-fluoren]-2-ones, the anti alcohols were favored in all cases. In the epoxidation of substituted spiro[cyclopent-2-ene-1,9′-fluorenes], the syn epoxides were favored. These distributions of the products can be interpreted in terms of orbital perturbations arising from interactions of the π orbitals of the aromatic and the carbonyl moieties or of the π orbitals of the aromatic and the olefin moieties, i.e., orbital mixing perturbation of the aromatic π orbitals through the π orbital of the bisected carbonyl (or olefin) group and the reciprocal perturbation of the π orbital of the carbonyl (or olefin) group arising from the orthogonal π aromatic orbitals.
- Ohwada, Tomohiko
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p. 8818 - 8827
(2007/10/02)
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- Regiospecific Syntheses of All Isomeric Nitrofluorenones and Nitrofluorenes by Transition Metal Catalyzed Cross-Coupling Reactions
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Regiospecific efficient syntheses of 1-, 2-, 3-, and 4-nitrofluorenones 8 and the corresponding nitrofluorenes 10 by palladium(0)-catalyzed cross-coupling reactions of aryl boronic acids 1 with bromonitrotoluenes 2 and bromonitrobenzene 3 are described.
- Iihama, T.,Fu, J.-m.,Bourguignon, M.,Snieckus, V.
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p. 184 - 188
(2007/10/02)
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- Non-specific tritiation of some carcinogenic aromatic amines
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2-Aminofluorene, 4-amino-3-methylbiphenyl, 4-amino-biphenyl and 4-amino-4'-fluorobiphenyl were tritiated by acid catalyzed exchange of the corresponding nitro compounds followed by catalytic reduction. The exchange reactions were carried out by heating the nitro compounds in [3H]-trifluoroacetic acid with a catalytic amount of trifluoromethanesulphonic acid (TFMS). No loss of tritium could be detected during the conversion of the tritiated nitro compounds into the corresponding amines by catalytic hydrogenation. Incorporation into the ortho position is very low (4%). During the metabolic activation and binding of the tritiated N-acetyl-2-aminofluorene to rat liver DNA in vivo, no tritium exchange occurred.
- Breeman,Kaspersen,Westra
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p. 741 - 750,748,749
(2007/10/05)
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