10198-89-7Relevant articles and documents
Pentanuclear iron catalysts for water oxidation: Substituents provide two routes to control onset potentials
Praneeth, Vijayendran K. K.,Kondo, Mio,Okamura, Masaya,Akai, Takuya,Izu, Hitoshi,Masaoka, Shigeyuki
, p. 4628 - 4639 (2019)
The development of robust and efficient molecular catalysts based on earth-abundant transition metals for water oxidation reactions is a challenging research target. Our group recently demonstrated the high activity and stability of a pentairon-based water oxidation electrocatalyst (M. Okamura, M. Kondo, R. Kuga, Y. Kurashige, T. Yanai, S. Hayami, V. K. K. Praneeth, M. Yoshida, K. Yoneda, S. Kawata and S. Masaoka, Nature, 2016, 530, 465-468). However, the development of strategies to decrease onset potentials for catalysis remains challenging. In this article, we report the construction of a series of pentanuclear iron complexes by introducing electron-donating (methyl) and electron-withdrawing (bromo) substituents on the ligand. Two newly synthesized complexes exhibited five reversible redox processes, similar to what is seen with the parent complex. These complexes can also serve as homogeneous catalysts for water oxidation reactions, and the faradaic efficiencies of the reactions were high. Additionally, the onset potentials of the newly developed complexes were lower than that of the parent complex. Mechanistic insights revealed that there are two methods for decreasing onset potentials: control of the redox potentials of the pentairon complex and control of the reaction mechanism.
Efficient electroluminescence of sky-blue iridium(III) complexes for organic light-emitting diodes
Su, Ning,Shen, Cheng-Zhen,Zheng, You-Xuan
, p. 100 - 106 (2018)
Two novel sky-blue iridium(III) complexes Ir(dfppy)2pypzpy and Ir(dfppy)2phpzpy were synthesized, in which 2-(2,4-difluorophenyl)pyridine (dfppy) was used as main ligand, 2,2'-(1H-pyrazole-3,5-diyl)dipyridine (pypzpy) and 2-(3-2-(3-p
Highly efficient green electroluminescence of iridium(iii) complexes based on (1: H -pyrazol-5-yl)pyridine derivatives ancillary ligands with low efficiency roll-off
Su, Ning,Lu, Guang-Zhao,Zheng, You-Xuan
, p. 5778 - 5784 (2018)
Four iridium(iii) complexes, namely Ir-me, Ir-cf3, Ir-py, and Ir-ph, were synthesized, in which 2-(4-trifluoromethyl)phenylpyridine (tfmppy) was used as the main ligand and 2-(3-methyl-1H-pyrazol-5-yl)pyridine (mepzpy), 2-(3-(trifluoromethyl)-1H-pyrazol-5-yl)pyridine (cf3pzpy), 2,2′-(1H-pyrazole-3,5-diyl)dipyridine (pypzpy), and 2-(3-phenyl-1H-pyrazol-5-yl)pyridine (phpzpy) were applied as ancillary ligands, respectively. All complexes showed similar green light peaking at 494-499 nm with high phosphorescence quantum efficiency (0.76-0.82). The organic light-emitting diodes (OLEDs) with the structure of ITO/HATCN (hexaazatriphenylenehexacabonitrile) (5 nm)/TAPC (bis[4-(N,N-ditolylamino)-phenyl]cyclohexane, 50 nm)/Ir complexes (8 wt%): TCTA (4,4′,4′′-tri(9-carbazoyl)triphenylamine, 20 nm)/TmPyPB (1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, 40 nm)/LiF (1 nm)/Al (100 nm) displayed high current efficiency with low efficiency roll-off. Moreover, the device based on the Ir-me complex exhibited the best performances with a maximum luminance of 38 155 cd m-2, maximum current efficiency of 92 cd A-1, and a maximum external quantum efficiency of 28.90%. These results suggested that green Ir(iii) complexes were obtained by modification of the ppy ligand and rational introduction of (1H-pyrazol-5-yl)pyridine derivatives as the ancillary ligands for high efficient OLEDs.
Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents
Jansa, Josef,Schmidt, Ramona,Mamuye, Ashenafi Damtew,Castoldi, Laura,Roller, Alexander,Pace, Vittorio,Holzer, Wolfgang
supporting information, p. 895 - 902 (2017/06/21)
A synthesis of tetrasubstituted pyrazoles containing two, three or four pyridinyl substituents is described. Hence, the reaction of 1,3-dipyridinyl-1,3-propanediones with 2-hydrazinopyridine or phenylhydrazine, respectively, affords the corresponding 1,3,5-trisubstituted pyrazoles. Iodination at the 4-position of the pyrazole nucleus by treatment with I2/HIO3 gives the appropriate 4-iodopyrazoles which served as starting materials for different cross-coupling reactions. Finally, Negishi cross-coupling employing organozinc halides and Pd catalysts turned out to be the method of choice to obtain the desired tetrasubstituted pyrazoles. The formation of different unexpected reaction products is described. Detailed NMR spectroscopic investigations (1H, 13C, 15N) were undertaken with all products prepared. Moreover, the structure of a condensation product was confirmed by crystal structure analysis.
