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1月, 2016の投稿を表示しています

Previous Article Next Article ASAP Copper Complexes with NH-Imidazolyl and NH-Pyrazolyl Units and Determination of Their Bond Dissociation Gibbs Energies

Alexander Wilting † ,  Merle Kügler † , and  Inke Siewert * † †   Georg-August-University Göttingen , Tammannstr. 4, D-37077 Göttingen,  Germany Inorg. Chem. , Article ASAP DOI:  10.1021/acs.inorgchem.5b02084 Publication Date (Web): January 20, 2016 Copyright © 2016 American Chemical Society *E-mail:  inke.siewert@chemie.uni-goettingen.de . Synopsis The bond dissociation Gibbs energy has been determined for two isoelectronic Cu complexes having an imidazole and pyrazole unit, respectively. Both complexes show a thermodynamic coupling between the redox event at the metal center and the proton transfer event at the ligand backbone. http://pubs.acs.org/doi/10.1021/acs.inorgchem.5b02084 Abstract We synthesized two dinuclear copper complexes, which have ionizable  N  imidazole and  N pyrazole protons in the ligand, respectively, and determined the BDFE of the hypothetical H atom transfer reactions Cu II (LH –1 ...

Iron catalyzed highly enantioselective epoxidation of cyclic aliphatic enones with aqueous H2O2

Olaf Cussó ,  Marco Cianfanelli ,  Xavi Ribas ,  Robertus J.M. Klein Gebbink , and  Miquel Costas J. Am. Chem. Soc. , Just Accepted Manuscript DOI:  10.1021/jacs.5b12681 Publication Date (Web): January 22, 2016 Copyright © 2016 American Chemical Society 1 QBIS Research Group, Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Uni ‐ versitat de Girona, Campus Montilivi, Girona E ‐ 17071, Catalonia, Spain. 2 Organic Chemistry & Catalysis, Debye Institute for Nanomaterials Science, Utrecht University. Universiteitsweg 99, 3584 CG Utrecht, The Netherlands.  http://pubs.acs.org/doi/abs/10.1021/jacs.5b12681 Abstract An iron complex with a C1-symmetric tetradentate N-based ligand catalyze the asymmetric epoxidation of cyclic enones and cyclohexene ketones with aqueous hydrogen peroxide, providing the corresponding epoxides in good to excellent yields and enantioselectivities (up to 99 % yield, and 95 %...

Homogeneous Photocatalytic Water Oxidation with a Dinuclear CoIII–Pyridylmethylamine Complex

Tomoya Ishizuka † ,  Atsuko Watanabe † ,  Hiroaki Kotani † ,  Dachao Hong † ,  Kenta Satonaka † ,  Tohru Wada ‡ ,  Yoshihito Shiota § ,  Kazunari Yoshizawa § ⊥ ,  Kazuaki Ohara ¶ ,  Kentaro Yamaguchi ¶ ,  Satoshi Kato ∥ ,  Shunichi Fukuzumi * ∥ ⧫ ∞ , and  Takahiko Kojima * † †  Department of Chemistry, Graduate School of Pure and Applied Sciences,  University of Tsukuba , 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571,  Japan ‡  Department of Chemistry, College of Science,  Rikkyo University , 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501,  Japan §  Institute for Materials Chemistry and Engineering,  Kyushu University , Motooka, Nishi-ku, Fukuoka 819-0395,  Japan ⊥  Elements Strategy Initiative for Catalysts & Batteries,  Kyoto University , Nishi-ku, Kyoto 615-8520,  Japan ¶  Faculty of Pharmaceutical Science at Kagawa Campus,  Tokushima Bunri ...

Spectroscopic and Crystallographic Evidence for the Role of a Water- Containing H‐Bond Network in Oxidase Activity of an Engineered Myoglobin

J. Am. Chem. Soc. , Article ASAP DOI: 10.1021/jacs.5b12004 Publication Date (Web): December 30, 2015 Copyright © 2015 American Chemical Society Igor D. Petrik, † , § Roman Davydov, ‡ , § Matthew Ross, † , ‡ Xuan Zhao, † Brian Ho ff man, * , ‡ and Yi Lu * , †   † Department of Chemistry, University of Illinois at Urbana − Champaign, Urbana, Illinois 61801, United States ‡ The Department of Chemistry, Northwestern University, Evanston, Illinois 60201, United States  http://pubs.acs.org/doi/pdf/10.1021/jacs.5b12004 Abstract Heme-copper oxidases (HCOs) catalyze efficient reduction of oxygen to water in biological respiration. Despite progress in studying native enzymes and their models, the roles of non-covalent interactions in promoting this activity are still not well understood. Here we report EPR spectroscopic studies of cryoreduced oxy-F33Y-Cu B Mb, a functional model of HCOs engineered in myoglobin (Mb). We find that cryoreduction at 77 K of th...

Synthesis and Catalytic Reactivity of a Dicopper(II) μ-η2:η2-Peroxo Species Supported by 1,4,7-Tri-tert-butyl-1,4,7-triazacyclononane

Inorganic Chemistry: Latest Articles (ACS Publications)  by Gregory J. Karahalis, Arumugam Thangavel, Bryant Chica, John Bacsa, R. Brian Dyer and Christopher C. Scarborough Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States O 2 -derived Cu n O 2 adducts are attractive targets for aerobic oxidation catalysis because of their remarkable reactivity, but oxidation of the supporting ligand limits catalytic turnover. We report that t Bu 3 tacn (1,4,7-tri- tert -butyl-1,4,7-triazacyclo- nonane) supports a dicopper(II) μ - η 2 : η 2 -peroxo species with the highest solution stability outside of an enzyme. Decomposition of this species proceeds without oxidation of the t Bu 3 tacn ligand. Additive-free catalytic aerobic oxidation reactions at or above room temperature are described, highlighting the potential of oxidatively robust ligands in aerobic copper catalysis. Inorganic Chemistry DOI: 10.1...