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981.
Ketimido Metallophthalocyanines: An Approach to Phthalocyanine‐Supported Mononuclear High‐Valent Ruthenium Complexes 下载免费PDF全文
Dr. Jie‐Sheng Huang Dr. Kwok‐Ming Wong Dr. Sharon Lai‐Fung Chan Ken Chi‐Hang Tso Tao Jiang Prof. Dr. Chi‐Ming Che 《化学:亚洲杂志》2014,9(1):338-350
A “metal–ketimine+ArI(OR)2” approach has been developed for preparing metal–ketimido complexes, and ketimido ligands are found to stabilize high‐valent metallophthalocyanine (M? Pc) complexes such as ruthenium(IV) phthalocyanines. Treatment of bis(ketimine) ruthenium(II) phthalocyanines [RuII(Pc)(HN?CPh2)2] ( 1a ) and [RuII(Pc)(HNQu)2] ( 1b ; HNQu=N‐phenyl‐1,4‐benzoquinonediimine) with PhI(OAc)2 affords bis(ketimido) ruthenium(IV) phthalocyanines [RuIV(Pc)(N?CPh2)2] ( 2a ) and [RuIV(Pc)(NQu)2] ( 2b ), respectively. X‐ray crystal structures of 1b and [RuII(Pc)(PhN?CHPh)2] ( 1c ) show Ru? N(ketimine) distances of 2.075(4) and 2.115(3) Å, respectively. Complexes 2a , 2b readily revert to 1a , 1b upon treatment with phenols. 1H NMR spectroscopy reveals that 2a , 2b are diamagnetic and 2b exists as two isomers, consistent with a proposed eclipsed orientation of the ketimido ligands in these ruthenium(IV) complexes. The reaction of 1a , 1b with PhI(OAc)2 to afford 2a , 2b suggests the utility of ArI(OR)2 as an oxidative deprotonation agent for the generation of high‐valent metal complexes featuring M? N bonds with multiple bonding characters. DFT and time‐dependent (TD)‐DFT calculations have been performed on the electronic structures and the UV/Vis absorption spectra of 1b and 2b , which provide support for the diamagnetic nature of 2b and reveal a significant barrier for rotation of the ketimido group about the Ru? N(ketimido) bond. 相似文献
982.
Luminescent Palladium(II) Complexes with π‐Extended Cyclometalated [RC^N^NR′] and Pentafluorophenylacetylide Ligands: Spectroscopic,Photophysical, and Photochemical Properties 下载免费PDF全文
A series of cyclometalated PdII complexes that contain π‐extended R? C^N^N? R′ (R? C^N^N? R′=3‐(6′‐aryl‐2′‐pyridinyl)isoquinoline) and chloride/pentafluorophenylacetylide ligands have been synthesized and their photophysical and photochemical properties examined. The complexes with the chloride ligand are emissive only in the solid state and in glassy solutions at 77 K, whereas the ones with the pentafluorophenylacetylide ligand show phosphorescence in the solid state (λmax=584–632 nm) and in solution (λmax=533–602 nm) at room temperature. Some of the complexes with the pentafluorophenylacetylide ligand show emission with λmax at 585–602 nm upon an increase in the complex concentration in solutions. These PdII complexes can act as photosensitizers for the light‐induced aerobic oxidation of amines. In the presence of 0.1 mol % PdII complex, secondary amines can be oxidized to the corresponding imines with substrate conversions and product yields up to 100 and 99 %, respectively. In the presence of 0.15 mol % PdII complex, the oxidative cyanation of tertiary amines could be performed with product yields up to 91 %. The PdII complexes have also been used to sensitize photochemical hydrogen production with a three‐component system that comprises the PdII complex, [Co(dmgH)2(py)Cl] (dmgH=dimethylglyoxime; py=pyridine), and triethanolamine, and a maximum turnover of hydrogen production of 175 in 4 h was achieved. The excited‐state electron‐transfer properties of the PdII complexes have been examined. 相似文献
983.
Designed Synthesis of a Highly Conjugated Hexaethynylbenzene‐Based Host for Supramolecular Architectures 下载免费PDF全文
Dr. Yongjun Li Liang Xu Dr. Sharon Lai‐Fung Chan Prof. Yuliang Li Runsheng Jiang Prof. Huibiao Liu Prof. Chi‐Ming Che 《化学:亚洲杂志》2014,9(10):2842-2849
The construction of efficient synthetic functional receptors with tunable cavities, and the self‐organization of guest molecules within these cavities through noncovalent interactions can be challenging. Here we have prepared a double‐cavity molecular cup based on hexaethynylbenzene that possesses a highly π‐conjugated interior for the binding of electron‐rich guests. X‐ray crystallography, NMR spectroscopy, UV/Vis spectroscopy, fluorescent spectroscopy, cyclic voltammetry, and SEM were used to investigate the structures and the binding behaviors. The results indicated that the binding of a guest in one cavity would affect the binding of the same or another guest in the other cavity. The effect of electron transfer in this system suggests ample opportunities for tuning the optical and electronic properties of the molecular cup and the encapsulated guest. The encapsulation of different guests would also lead to different aggregate nanostructures, which is a new way to tune their supramolecular architectures. 相似文献
984.
Efficient Red Electroluminescent Devices with Sterically Hindered Phosphorescent Platinum(II) Schiff Base Complexes and Iridium Complex Codopant 下载免费PDF全文
Dr. Liang Zhou Chun‐Lam Kwong Dr. Chi‐Chung Kwok Dr. Gang Cheng Prof. Hongjie Zhang Prof. Chi‐Ming Che 《化学:亚洲杂志》2014,9(10):2984-2994
Sterically hindered platinum(II) Schiff base complexes were prepared. Complex 4 , which displays red emission with a quantum yield of 0.29 in a thin film and a self‐quenching rate constant of 1×10?7 dm3 mol?1 s?1, was used to fabricate organic light‐emitting diodes with single or double emissive layers (EMLs). An iridium(III) complex with a wide band gap was codoped into the electron‐dominant EML to act as a deep electron trapper, and red‐light‐emitting devices with the highest current, power, and external quantum efficiencies of 20.43 cd A?1 18.33 Lm W?1, and 11.7 %, respectively, were fabricated. A high current efficiency and EQE of up to 14.69 cd A?1 and 8.3 %, respectively, were achieved at a high brightness of 1000 cd m?2. The significant delay of efficiency roll‐off is attributed to the bulky 3D structure of the norbornene moiety at the periphery of the Schiff base ligand of 4 and to the new device design strategy. The fabricated device had a projected lifetime (LT50) of 18 000 h. 相似文献
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Che‐Man Cheng Xiao‐Qing Jin Yi‐Min Wei 《Numerical Linear Algebra with Applications》2006,13(7):513-521
A matrix is said to be stable if the real parts of all the eigenvalues are negative. In this paper, for any matrix An, we give some sufficient and necessary conditions for the stability of superoptimal preconditioner EU(An) proposed by Tyrtyshnikov (SIAM J. Matrix Anal. Appl. 1992; 13 :459–473). Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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