- Cationic Iridium Complexes with 3,4,5-Triphenyl-4 H-1,2,4-Triazole Type Cyclometalating Ligands: Synthesis, Characterizations, and Their Use in Light-Emitting Electrochemical Cells
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Cationic iridium complexes that show blue-shifted emission and high phosphorescent efficiency have been pursued for their optoelectronic applications. Five cationic iridium complexes with 3,4,5-triphenyl-4H-1,2,4-triazole (tPhTAZ) type cyclometalating ligands (C^N) and 2,2′-bipyridine or 2-(pyridin-2-yl)-1H-benzo[d]imidazole type ancillary ligands (N^N) have been designed and synthesized. Their structures have been confirmed by X-ray crystallography, and their photophysical and electrochemical properties have been comprehensively characterized. In solution and thin films, the complexes afford efficient yellow to blue-green emission. The highest occupied molecular orbitals (HOMOs) of these complexes are delocalized over the C^N ligand and the iridium ion, and compared with the conventional 2-phenylpyridine (Hppy) ligand, the tPhTAZ ligand largely shifts the emission of the complex toward blue by over 40 nm through stabilizing the HOMO. Moreover, the peripheral phenyl rings in tPhTAZ provide steric hindrance to the complexes, which suppresses phosphorescence concentration-quenching of the complexes, leading to high luminescent efficiencies in neat films. Theoretical calculations have shown that the emission of the complexes originates from either the charge-transfer state (Ir/C^N → N^N) or the C^N/N^N-centered 3π-π? state, depending on the local surrounding of the complex. The complexes exhibit good electrochemical stability with reversible oxidation and reduction processes in solution. Solid-state light emitting electrochemical cells (LECs) using the complexes afford yellow to blue-green emission, with peak current efficiencies of up to 34.7 cd A-1 and maximum brightness of up to 256 cd m-2 at 3.0 V, which are among the highest for LECs based on cationic iridium complexes reported so far, indicating the great potential for the use of tPhTAZ-type C^N ligands in construction of cationic iridium complexes for LEC applications.
- Bai, Rubing,Chen, Mengzhen,He, Lei,Meng, Xianwen
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- Synthesis of 1,2,4-Triazoles, N-Fused 1,2,4-Triazoles and 1,2,4-Oxadiazoles via Molybdenum Hexacarbonyl-Mediated Carbonylation of Aryl Iodides
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A convenient and efficient protocol has been developed for the synthesis of 1,2,4-triazoles, N-fused 1,2,4-triazoles and 1,2,4-oxadiazoles using molybdenum hexacarbonyl where, for the first time, molybdenum hexacarbonyl acts as a convenient and reliable s
- Nakka, Mangarao,Tadikonda, Ramu,Nakka, Srinivas,Vidavalur, Siddaiah
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supporting information
p. 520 - 525
(2016/02/27)
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- A simple and efficient synthesis of 3,4,5-trisubstituted/N-fused 1,2,4-triazoles via ceric ammonium nitrate catalyzed oxidative cyclization of amidrazones with aldehydes using polyethylene glycol as a recyclable reaction medium
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An environmentally benign protocol is described for the synthesis of 3,4,5-trisubstituted 1,2,4-triazoles and N-fused 1,2,4-triazoles via ceric ammonium nitrate catalyzed oxidative cyclization of amidrazones and aldehydes using polyethylene glycol as recyclable reaction medium. This protocol is effective toward various substrates having different functionalities. The easy recyclability of the reaction medium makes the process economic and potentially viable for commercial applications.
- Nakka, Mangarao,Tadikonda, Ramu,Rayavarapu, Srinuvasarao,Sarakula, Prasanthi,Vidavalur, Siddaiah
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p. 517 - 525
(2015/02/19)
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- Ligand-free copper(0) catalyzed direct C-H arylation of 1,2,4-triazoles and 1,3,4-oxadiazoles with aryl iodides in PEG-400
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A ligand-free copper catalyzed approach has been developed to the synthesis of 3,4,5-triaryl-1,2,4-triazoles and 2,5-diaryl-1,3,4-oxadiazoles by the direct arylation of corresponding 3,4-diaryl-1,2,4-triazoles and 2-aryl-1,3,4-oxadiazoles with aryl iodides using PEG-400 as reaction medium. The procedure is experimentally simple and free from addition of external chelating ligands or co-catalysts.
- Tadikonda, Ramu,Nakka, Mangarao,Rayavarapu, Srinuvasarao,Kalidindi, Siva Prasada Kumar,Vidavalur, Siddaiah
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supporting information
p. 690 - 692
(2015/01/30)
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- Br?nsted acid-catalyzed simple and efficient synthesis of 1,2,4-triazoles and 1,2,4-oxadiazoles using 2,2,2-trichloroethyl imidates in PEG
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A facile and highly efficient synthesis of 3,4,5-trisubstituted 1,2,4-triazoles and 3,5-disubstituted 1,2,4-oxadiazoles from 2,2,2-trichloroethyl imidates using PEG as a solvent and employing PTSA as the catalyst under mild conditions is described.
- Mangarao, Nakka,Mahaboob Basha, Gajula,Ramu, Tadikonda,Srinuvasarao, Rayavarapu,Prasanthi, Sarakula,Siddaiah, Vidavalur
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supporting information
p. 177 - 179
(2014/01/06)
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- Tunable protic ionic liquids as solvent-catalysts for improved synthesis of multiply substituted 1,2,4-triazoles from oxadiazoles and organoamines
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More than green alternatives to traditional volatile molecular organic solvents, protic ionic liquids as dual solvent-catalysts have been successfully used to promote reactions of organoamines with oxadiazoles to afford sterically hindered 1,2,4-triazoles. Among the tested protic ionic liquids, pyridinium trifluoroacetate and acetate showed the highest efficiency for the reactions of arylamines and alkylamines, respectively, indicating that tunable catalysis could be readily effected with protic ionic liquid solvent-catalysts by simply tuning their cation and anion counterparts. A general and efficient approach has been developed for synthesis of multiply substituted 1,2,4-triazoles based on the tunable protic ionic liquid solvent-catalyst systems.
- Chen, Xiaofeng,Liu, Rui,Xu, Yuan,Zou, Gang
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experimental part
p. 4813 - 4819
(2012/07/31)
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- Copolyfluorenes containing pendant bipolar carbazole and 1,2,4-triazole groups: Synthesis, characterization, and optoelectronic applications
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Three novel copolyfluorenes (P1-P3) containing pendant bipolar groups (2.5-7.7 mol %), directly linked hole-transporting carbazole and electron-transporting aromatic 1,2,4-triazole, were synthesized by the Suzuki coupling reaction and applied to enhance emission efficiency of polymer light-emitting diodes based on conventional MEH-PPV. The bipolar groups not only suppress undesirable green emission of polyfluorene under thermal annealing, but also promote electron- and hole-affinity of the resulting copolyfluorenes. Blending the bipolar copolyfluorenes with MEH-PPV results in significant enhancement of device performance [ITO/PEDOT:PSS/MEH-PPV+P1, P2 or P3/Ca(50 nm)/Al(100 nm)]. The maximum luminance and luminance efficiency were enhanced from 3230 cd/m2 and 0.29 cd/A of MEH-PPV-only device to 15,690 cd/m2 and 0.81 cd/A (blend device with MEH-PPV/P3 = 94/6 containing about 0.46 wt % of pendant bipolar residues), respectively. Our results demonstrate the efficacy of the bipolar copolyfluorenes in enhancing emission efficiency of MEH-PPV.
- Wu, Chia-Shing,Chen, Yun
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body text
p. 3928 - 3938
(2012/07/17)
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- Copolyfluorenes containing pendant bipolar groups: Synthesis, optoelectronic properties and applications
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This article reports the synthesis of copolyfluorenes (P1-P3) containing pendant bipolar groups (2.1-8.2 mol%), directly linked to hole-transporting triphenylamine and electron-transporting aromatic 1,2,4-triazole, by the Suzuki coupling reaction and their application in improving PLED performance of conventional MEH-PPV. The bipolar groups not only suppress undesirable green emission of polyfluorene under thermal annealing, but also promote electron- and hole-affinity of the resulting copolyfluorenes. Blending bipolar model compound M0 with MEH-PPV results in enhancement of device performance [ITO/PEDOT:PSS/M0 + MEH-PPV/Ca(50 nm)/Al(100 nm)]. Maximum luminance and luminance efficiency were increased from 3160 cd/m2 and 0.24 cd/A of MEH-PPV-only device to 6830 cd/m2 and 0.50 cd/A. Moreover, blending the bipolar copolyfluorenes with MEH-PPV further improves the device efficiency, with the maximum luminance and luminance efficiency being significantly enhanced up to 11090 cd/m2 and 0.56 cd/A (ca. 0.4 wt% of bipolar residue), respectively. Our results demonstrate the efficacy of the bipolar copolyfluorenes and model compound M0 in enhancing emission efficiency of MEH-PPV.
- Wu, Chia-Shing,Chen, Yun
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experimental part
p. 7700 - 7709
(2012/01/12)
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- A novel synthesis of 3,4,5-triaryl-1,2,4-4H-triazoles from 2,5-diaryl-1,3,4-oxadiazoles and aluminium anilides
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3,4,5-Triaryl-1,2,4-4H-triazoles have been prepared in 70-91% yields by a simple and easy to control one-pot procedure from 2,5- diaryl-1,3,4-oxadiazoles and aluminium anilides.
- Chiriac, Constantin I.,Tanasa, Fulga,Nechifor, Marioara
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experimental part
p. 175 - 177
(2011/08/03)
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- Copper-mediated direct arylation of 1,3,4-oxadiazoles and 1,2,4-triazoles with aryl iodides
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The copper-mediated direct arylation of 1,3,4-oxadiazoles and 1,2,4-triazoles with aryl iodides proceeds efficiently in the presence of suitable ligands and bases. This method allows the installation of a variety of aryl moieties bearing a functional group such as ketone, ester, or nitrile so as to enable the facile construction of various functionalized oxadiazole and triazole core π systems.
- Kawano, Tsuyoshi,Yoshizumi, Tomoki,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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supporting information; experimental part
p. 3072 - 3075
(2009/12/06)
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- Synthesis and biological action of 3,4-disubstituted 5- arylsulphonylamine-1,2,4-triazoles
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The synthesis of 3,4-disubstituted 5-arylsulphonylamine-1,2,4-triazoles is described. The antimicrobial activities of the compounds were investigated as well as their acute toxicity.
- Modzelewska-Banachiewicz,Matosiuk
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p. 588 - 589
(2007/10/03)
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- Synthesis of 3H-1,3,4-Benzotriazepines from 5-Aryltetrazoles and N-Arylbenzimidoyl Chlorides
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Heating of 5-phenyltetrazole with N-phenylbenzimidoyl chloride in the absence of solvent or in toluene, dioxane, benzonitrile, pyridine or N,N-dimethylformamide results in the formation of 3,4,5-triphenyl-1,2,4-triazole 1.Thermolysis of 1-imidoyl- and 2-i
- Koldobskii, Grigorii,Ivanova, Svetlana,Nikonova, Irina,Zhivich, Alexander,Ostrovskii, Vladimir
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p. 596 - 599
(2007/10/02)
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- REACTIONS OF α-NITROALDAZINES WITH NUCLEOPHILIC REAGENTS
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The reactions of the previously unknown α-nitroazines of aromatic aldehydes with aniline and sodium azide lead to derivatives of 1,2,4-triazole and tetrazole as a result of successive substitution of the nitro group and heterocyclization.
- Nekrasova, G. V.,Lyamina, T. N.,Lipina, E. S.,Berkova, G. A.,Paperno, T. Ya.,et al.
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p. 794 - 797
(2007/10/02)
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- THE CHEMICAL SIMULATION OF THE "ATP-IMIDAZOLE" CYCLE
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The synthetic strategy inherent in the "ATP-Imidazole" cycle and centred around the vicinal disposition of -NH2 and -CONH2 functions, has been demonstrated with anthranilamide (2) and 1-benzyl-5-aminoimidazole-4-carboxamide (1) as regeneratable carriers involving specifically N-alkylated quinazolin-4-ones, hypoxantines and adenines, as key intermediates.The isolation and characterization of the enamine (22) coupled with other observations has made it possible to rationalize the pathways involved in these cyclic operations.The practical utility of the synthetic strategy using regeneratable carriers has beem illustrated with the synthesis of a range of 1,5-disubstituted imidazoles.Whilst pathways leading to specific N-alkylation in the Natural cycle and in simulation studies are comparable, the subsequent events take place in a reverse order, primarily because of the divergence in the hydrolitic profile of the alkylated substrates.The action of dilute alkali on 3-alkylated quinazolin-4-ones leads to 2-3 rather than 3-4 bond rupture.Endeavours to promote the latter path, by blocking the 2 position gave unexpected results. 2-Methyl-3-phenacyl quinazolin-4-one gave with dilute alkali the novel aromatic tricyclic system (32) from trans-annular cyclization.On the other hand the 2-blocked 3-benzamido quinazolin-4-ones (33) and (34) gave triazoles (35) and (36) arising from the desired 3-4 rupture followed by cyclization initiated by the resulting amidine unit. 2-Phenil-3-benzamidoquinazolin-4-one (34) with distilled water at 200 deg C gave a number of products whicc have been identified and their formation explained.
- Ranganathan, Darshan,Farooqui, Firdous,Bhattacharyya, Diphti,Mehrotra, Sanjiv,Kesavan, K.
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p. 4481 - 4492
(2007/10/02)
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