- Extended heterocyclic systems 2. The synthesis and characterisation of (2-furyl)pyridines, (2-thienyl)pyridines, and furan-pyridine and thiophene-pyridine oligomers
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The Stetter procedure has been adapted to produce simple 2-furyl- and 2-thienyl-pyridines and their related oligomers, which have been characterised by 13C NMR spectroscopy. σ values for the 2-furyl and 2-thienyl rings have been deduced from the pK(a) values of the conjugate acids of the 2-furyl- and 2-thienylpyridines.
- Jones, R. Alan,Civcir, Pervin U.
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- Dark-field oxidative addition-based chemosensing: New bis-cyclometalated Pt(II) complexes and phosphorescent detection of cyanogen halides
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Heavy metal complexes that are phosphorescent at room temperature are becoming increasingly important in materials chemistry, principally due to their use in phosphorescent organic light-emitting devices (OLEDs). Their use in optical sensory schemes, however, has not been heavily explored. Homoleptic biscyclometalated Pt(II) complexes are known to undergo oxidative addition with appropriate electrophiles (principally alkyl halides) by either thermal or photochemical activation. We have applied this general reaction scheme to the development of a phosphorescence-based sensing system for cyanogen halides. To carry out structure-property relationship studies, a series of previously unreported Pt(II) complexes was prepared. Most of the complexes (excluding those that incorporated substituents on the ligands that forced steric crowding in the square plane) were strongly orange-red phosphorescent (Φ = 0.2-0.3) in a room-temperature oxygen-free solution. These sterically demanding ligands also accelerated the addition of cyanogen bromide to these complexes but slowed the addition of methyl iodide, indicating that the oxidative addition mechanisms for these two electrophiles is different. The lack of solvent-polarity effect on the addition of BrCN suggests a radical mechanism. Oxidative addition of BrCN to the metal complexes in solution or dispersed in poly(methyl methacrylate) gave blue-shifted emissive Pt(IV) complexes. The blue-shifted products give a dark-field sensing scheme that is in sharp contrast to energy transfer-based sensing schemes, which have limited signal-to-noise because of the presence of lower-energy vibronic bands of the energy donor that can overlap with the emission of the acceptor.
- Thomas III, Samuel W.,Venkatesan, Koushik,Mueller, Peter,Swager, Timothy M.
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- Bis/hetero aromatic compound and preparation method thereof
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The invention discloses a bi/hetero aromatic compound and a preparation method thereof. The structural formula of the bi/hetero aromatic compound is as shown in formula 3. The preparation method comprises the following steps: taking an aryl tetrafluorobor
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Paragraph 0035-0036
(2021/07/17)
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- Regioselective oxidative Pd-catalysed coupling of alkylboronic acids with pyridin-2-yl-substituted heterocycles
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A total of 19 alkylated heterocycles (thiophenes, benzothiophenes, pyrroles, furans) were prepared (36-99% yield) from the respective pyridin-2-yl-substituted precursors employing alkylboronic acids as the C-H alkylating reagents in an oxidative (Ag2
- Wippich, Julian,Schnapperelle, Ingo,Bach, Thorsten
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supporting information
p. 3166 - 3168
(2015/06/11)
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- Direct C-H arylation of thiophenes at low catalyst loading of a phosphine-free bis(alkoxo)palladium complex
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An efficient phosphine-free direct C-H arylation of thiophenes at the α-position has been developed at low catalyst loading of bis(alkoxo)palladium complex (Cat.I, 0.1-0.2 mol %). The developed synthetic method can be applied to the synthesis of α-aryl/heteroaryl thiophenes from aryl or heteroaryl bromides in good to excellent yields and is compatible with the substrates bearing electron-donating or electron-withdrawing groups. The reactivities of the 2- and 5-positions of thiophenes are equivalent and not dependent on steric hindrance under optimal conditions. This condition can also be applied to other heterocyclic moieties such as benzothiophene, benzofuran, and pyrrole with high conversion yields.
- Li, Yabo,Wang, Jingran,Huang, Mengmeng,Wang, Zhiwei,Wu, Yusheng,Wu, Yangjie
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p. 2890 - 2897
(2014/05/06)
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- Pd-catalyzed oxidative C-H/C-H cross-coupling of pyridines with heteroarenes
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We have developed for the first time a general, concise and highly selective method for the C2-heteroarylation of pyridines and related azines with a broad range of heteroarenes via a two-fold C-H activation, which streamlines the previous approaches that require the activated azine N-oxide as the coupling partner.
- Liu, Bo,Huang, Yumin,Lan, Jingbo,Song, Feijie,You, Jingsong
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p. 2163 - 2167
(2013/05/09)
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- Efficient Pd-catalyzed direct arylations of heterocycles with unreactive and hindered aryl chlorides
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A highly electron-rich Pd complex can efficiently catalyze the direct arylation of heteroaromatics with unreactive and sterically congested aryl chlorides.
- Ghosh, Debalina,Lee, Hon Man
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supporting information
p. 5534 - 5537,4
(2012/12/12)
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- Homoleptic Cyclometalated Iridium Complexes with Highly Efficient Red Phosphorescence and Application to Organic Light-Emitting Diode
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Phosphorescence studies of a series of facial homoleptic cyclometalated iridium(III) complexes have been carried out. The complexes studied have the general structure Ir(III)(C-N)3, where (C-N) is a monoanionic cyclometalating ligand: 2-(5-methylthiophen-2-yl)pyridinato, 2-(thiophen-2-yl)-5-trifluoromethylpyridinato, 2,5-di(thiophen-2-yl)pyridinato, 2,5-di(5-methylthiophen-2-yl)pyridinato, 2-(benzo[b]thiophen-2-yl)pyridinato, 2-(9,9-dimethyl-9H-fluoren-2-yl)pyridinato, 1-phenylisoquinolinato, 1-(thiophen-2yl)isoquinolinato, or 1-(9,9-dimethyl-9H-fluoren-2-yl)isoquinolinato. Luminescence properties of all the complexes at 298 K in toluene are as follows: quantum yields of phosphorescence φp = 0.08-0.29, emission peaks λ max = 558-652 nm, and emission lifetimes τ = 0.74-4.7 μs. Bathochromic shifts of the Ir(thpy)3 family [the complexes with 2-(thiophen-2-yl)pyridine derivatives] are observed by introducing appropriate substituents, e.g., methyl, trifluoromethyl, or thiophen-2-yl. However, φp of the red emissive complexes (λmax > 600 nm) becomes small, caused by a significant decrease of the radiative rate constant, kr. In contrast, the complexes with the 1-arylisoquinoline ligands are found to have marked red shifts of λmax and very high φp (0.19-0.26). These complexes are found to possess dominantly 3MLCT (metal-to-ligand charge transfer) excited states and have kr values approximately 1 order of magnitude larger than those of the Ir(thpy)3 family. An organic light-emitting diode (OLED) device that uses Ir(1-phenylisoquinolinato)3 as a phosphorescent dopant produces very high efficiency (external quantum efficiency ηex = 10.3% and power efficiency 8.0 Im/W at 100 cd/m2) and pure-red emission with 1931 CIE (Commission Internationale de L'Eclairage) chromaticity coordinates (x = 0.68, y = 0.32).
- Tsuboyama, Akira,Iwawaki, Hironobu,Furugori, Manabu,Mukaide, Taihei,Kamatani, Jun,Igawa, Satoshi,Moriyama, Takashi,Miura, Seishi,Takiguchi, Takao,Okada, Shinjiro,Hoshino, Mikio,Ueno, Kazunori
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p. 12971 - 12979
(2007/10/03)
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- A CONVENIENT SYNTHESIS OF FIVE-MEMBERED HETEROARYL -SUBSTITUTED PYRIDINES
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Five-membered heteroarylpyridines (3) or (4) such as furylpyridines, thienylpyridines, imidazolylpyridines and pyrrolylpyridines were obtained regioselectively in appreciable yields (40-67percent) by reaction of heteroaryllithium salts with N-ethoxycarbonylpyridinium chloride (1) followed by oxygen oxidation.
- Shiao, Min- Jen,Shih, Li- Hua,Chia, Win- Long,Chau, Tay- Yuan
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p. 2111 - 2118
(2007/10/02)
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