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 ring-opening polymerization (ROP) of ?-caprolactone catalysed by isomeric pyridyl β-diketonate iron(III) complexes
Lee, Sze-Ling,Hu, Fei-Long,Shang, Xiu-Juan,Shi, Yi-Xiang,Tan, Ai Ling,Mizera, Jens,Clegg, Jack K.,Zhang, Wen-Hua,Young, David J.,Lang, Jian-Ping
, p. 14457 - 14465 (2017)
A series of Fe(iii) complexes of β-diketonate ligands, 1-(2-pyridyl)-3-(3-pyridyl)-1,3-propanedione (L1), 1-(2-pyridyl)-3-(2-pyridyl)-1,3-propanedione (L2), 1-(2-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L3), 1-(3-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L4), 1-(3-pyridyl)-3-(3-pyridyl)-1,3-propanedione (L5) and 1-(4-pyridyl)-3-(4-pyridyl)-1,3-propanedione (L6), viz. [Fe(L1)3] (1), [Fe(L2)3] (2), [Fe(L3)3] (3), [Fe(L4)3] (4), [Fe(L5)3] (5) and [Fe(L6)3] (6) have been structurally characterized. All but one complex (1) catalyzed the ring-opening polymerization (ROP) of ?-caprolactone (?-CL) in near quantitative yield at 110 °C to give polymers with relatively narrow polydispersities (PDI). The comparison of in situ reaction and a reaction with preformed 1 indicated that the latter was a better catalyst, giving a higher molecular weight. Complex 2 catalyzed this reaction in a more modest yield reflecting its greater thermal stability, shorter Fe-O bonds and minimal distortion in fold angle among the isomeric complexes, suggesting that ligand dissociation is important for catalytic activity.
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
Formation of HoIII trinuclear clusters and GdIII monodimensional polymers induced by ortho and para regioisomers of pyridyl-functionalised a-diketones: Synthesis, structure, and magnetic properties
Andrews, Philip C.,Deacon, Glen B.,Frank, Rene,Fraser, Benjamin H.,Junk, Peter C.,MacLellan, Jonathan G.,Massi, Miliano,Moubaraki, Boujemaa,Murray, Keith S.,Silberstein, Morry
, p. 744 - 751 (2009)
Reaction of GdCl3(H2O)6 and 1,3-bis(pyridin-4-yl)propane-1,3-dione in methanol with an excess of triethylamine produced a monodimensional polymeric chain [Gd(p-dppd) 3-(H2O)]∞, whereas treatment of HoCl 3(H2O)6 with 1,3-bis(pyridin-2-yl)propane-1,3- dione yielded a trinuclear cluster [Ho3(o-dppd) 3(μ3-OH)2(H2O)4Cl 2]Cl2. The compounds were characterised by elemental analysis, IR spectroscopy and magnetism, and their structures were investigated by X-ray crystallography. The 8.20-μB magnetic-moment value of the polymeric [Gd(p-dppd)3(H2O)]∞, between 300 and 20 K, and the magnetisation isotherms (2-20 K; fields 0-5 T), are in agreement with essentially uncoupled single-ion Gd3+ f7 centres, a small decrease in μeff below 20 K being indicative of zero-field splitting. A temperature-dependent dc-susceptibility and magnetisation investigation of the trinuclear (tri-angular) [Ho 3(o-dppd)3(μ3-OH)2(H 2O)4Cl2]Cl2 revealed that spin-orbit and ligand-field effects on the Ho3+ centres, leading to thermal depopulation of Zeeman levels and consequent decreases in μeff values with decreasing temperature, are occurring rather than weak intra-cluster antiferromagnetic coupling. Frequency- and temperature-dependent acsusceptibility studies on this homometallic Ho3+ cluster did not show clear evidence for slow magnetisation reversal, characteristic of single-molecule magnetism (SMM), and this contrasts with such behaviour recently reported, elsewhere, for a Dy3+ triangle having the same core structure but with different chelating {O,O} ligands. Wiley-VCH Verlag GmbH & Co. KGaA, 2009.
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.
Lanthanoid pyridyl-β-diketonate 'triangles'. New examples of single molecule toroics
Caporale, Chiara,Fuller, Rebecca O.,Massi, Massimiliano,Murray, Keith S.,Ogden, Mark I.,Phonsri, Wasinee,Rajaraman, Gopalan,Sobolev, Alexandre N.,Swain, Abinash
, p. 17421 - 17432 (2020)
Trinuclear lanthanoid clusters have been synthesised and investigated as toroidal spin systems. A pyridyl functionalised β-diketonate, 1,3-bis(pyridin-2-yl)propane-1,3-dione (o-dppdH) has been used to synthesise a family of clusters of the form [Dy3(OH)2(o-dppd)3Cl2(H2O)4]Cl2·7H2O (1), [Tb3(o-dppd)3(μ3-OH)2(CH3CH2OH)3Cl3][Tb3(o-dppd)3(μ3-OH)2(H2O)(CH3CH2OH)2Cl3]Cl2·H2O (2), [Ho3(OH)2(o-dppd)3Cl(H2O)5]Cl3·3H2O (3) and [Er3(OH)2(o-dppd)3Cl2(H2O)3(CH3OH)]Cl2·3H2O·CH3OH (4). Despite the previous occurrence of this structural motif in the literature, these systems have not been widely investigated in terms of torodic behaviour. Magnetic studies were used to further characterise the complexes. DC susceptibility studies support weak antiferromagnetic exchange in the complexes. Slow magnetic relaxation behaviour is observed in the dynamic AC magnetic studies for complex 1. Theoretical studies predict that complex 1 and 3 have a non-magnetic ground state based on a toroidal arrangement of spins. Changes to the coordination environment in 2 do not support a toroic spin state. The prolate nature of the ErIII centres in complex 4 and large transverse anisotropy do not support the toroidal arrangement of lanthanoid spins in the complex.
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.
Mono- and Bi-nuclear complexes of the doubly bidentate, bridging ligand 4,6-Di(2-pyridyl)pyrimidine
Phillips, Ian G.,Steel, Peter J.
, p. 371 - 382 (2007/10/03)
Thirteen mononuclear, homobinuclear and heterobinuclear transition metal complexes of 4,6-di(2-pyridyl)pyrimidine have been prepared. Assignments of the 1H n.m.r. spectra of the molybdenum(0) and ruthenium(II) complexes were achieved by a combination of one- and two-dimensional n.m.r. techniques, especially 1D-TOCSY. For the ruthenium complexes, electronic absorption spectroscopy and cyclic voltammetry were used to probe the nature of the metal-ligand and, for the binuclear complexes, metal-metal interactions. The complexes have low HOMO-LUMO energy gaps. Metal-metal interactions are shown to be of similar magnitude to those in complexes of the better-studied ligands 2,2′-bipyrimidine and 2,3-di(2-pyridyl)pyrazine.
