Read by QxMD icon Read


Marian Hebenbrock, Linda Stegemann, Jutta Kösters, Nikos L Doltsinis, Jens Müller, Cristian A Strassert
A versatile design strategy is presented towards new monoanionic pincer luminophores, showing that cyclometallating C^N^N ligands can yield phosphorescent Pt(ii) complexes even if a neutral 1,2,3-triazole ring is inserted by click chemistry. The overall charge, intermolecular interactions and excited state properties can be manipulated and controlled by varying the nature of the ancillary ligand, and its effect on the structural and the triplet state characteristics can be thoroughly investigated and correlated by means of theory and spectroscopy...
February 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
N Wachter, M Mentzel, G Krischak, C Häderer, J Gülke
BACKGROUND: Peripheral lesions of the median nerve cause characteristic changes of the grip function of the hand. For evaluating grip force changes, measurement by dynamometers (JAMAR dynamometer and pinch dynamometer) is of high relevance. In this study the ability of grip force measurements of different grip forms was evaluated to discriminate between a simulated median nerve lesion and healthy subjects. MATERIAL AND METHODS: In 21 healthy subjects, the grip force of power grip was measured by the JAMAR dynamometer at the second stage including measurement of force at the fingertips and the thenar by a sensor glove...
February 20, 2017: Der Unfallchirurg
Jacek A Kopec, Jolanda Cibere, Linda C Li, Charlie Zhang, Morgan Barber, Hong Qian, Hubert Wong, Gavin Steininger, Helen Prlic, Jacqueline Simatovic, Charles Ratzlaff, Eric C Sayre, Joanna Ye, Bruce B Forster, John M Esdaile
OBJECTIVES: The purpose of the study was to determine if physical activity (PA) is a risk factor for persistent or recurrent hip pain in young and middle-aged persons with and without radiographic findings of cam or pincer morphology (CPM). METHODS: A population sample of persons aged 20-49 with (cases) and without (controls) hip pain in Metro Vancouver, Canada, was selected through random digit dialing. Self-reported PA was expressed as average energy expenditure (MET-hours) per year, over lifetime...
February 17, 2017: Osteoarthritis and Cartilage
Jakub Pedziwiatr, Ion Ghiviriga, Khalil A Abboud, Adam S Veige
This report describes a synthetic protocols and the crystal structures involving a novel pincer-type H3[NNN] ligand, namely di-μ-bromido-μ-{2-(2,2-di-methylpropanimido-yl)-N-[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-bis-[(diethyl ether)lithium], [Li2Br2(C24H33N3)(C4H10O)2] (1) and a dinuclear metal complex, namely di-μ-bromido-2:3κ(4)Br:Br-bis-{2-(2,2-di-methylpropanimido-yl)-N-[2-(2,2-di-methyl-propanimido-yl)-4-methyl-phen-yl]-4-methylaniline}-1κ(3)N,N',N'';4κ(3)N,N',N''-tetra-μ-iso-propano-lato-1:2κ(4)O:O;3:4κ(4)O:O-diiso-propano-lato-1κO,4κO-2,3-dilithium-1,4-dititanium, [Li2Ti2Br2(C24H32N3)2(C3H7O)6] or {[NHNNH]Ti(O (i) Pr)3(LiBr)2}2 (2)...
February 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
Nicolas Leconte, Jules Moutet, Khrystyna Herasymchuk, Ryan M Clarke, Christian Philouze, Dominique Luneau, Tim Storr, Fabrice Thomas
The electron-rich pincer ligand 1 has been synthesized and chelated to manganese. The octahedral Mn(iv) bis(diiminosemiquinonate) and Mn(v) (diiminobenzoquinone) (diiminosemiquinonate) radicals were structurally characterized.
February 17, 2017: Chemical Communications: Chem Comm
Binju Wang, Sason Shaik
QM/MM calculations reveal that the nickel pincer complex in lactate racemase functions as a reversible "single-center electrode" that accepts and donates back an electron. In this way, it catalyzes the isomerization process d-lactate⇌l-lactate through successive proton-coupled electron-transfer steps.
February 3, 2017: Angewandte Chemie
Eric W Dahl, Thomas Louis-Goff, Nathaniel K Szymczak
Modification of the classic terpyridine pincer ligand with pendent NHR (R = mesityl) groups provides enhanced activity and stability in Ru-catalyzed dehydrogenation catalysis. These second sphere modifications furnish highly active catalysts for the oxidant-free dehydrogenative oxidation of primary alcohols to carboxylates and facilitate catalyst recycling.
February 3, 2017: Chemical Communications: Chem Comm
Jonathan M Frank, Jorge Chahla, Justin J Mitchell, Eduardo Soares, Marc J Philippon
Femoroacetabular impingement (FAI) is an increasingly recognized cause of hip pain. This pathology often involves abnormal femoral neck shape (cam-type FAI), acetabular over coverage (pincer-type FAI), or mixed pathology. Surgical treatment of this entity includes labral repair and femoral head-neck osteochondroplasty. A mindful arthroscopic technique is of paramount importance, because maintaining the integrity of the labrum and a corresponding neck volume has been reported to be vital in maintaining the hip suction seal...
December 2016: Arthroscopy Techniques
Jian Sun, Lun Luo, Yi Luo, Liang Deng
N-Heterocyclic carbene based pincer ligands bearing a central silyl donor, [CSiC](-) , have been envisioned as a class of strongly σ-donating ligands that can be used for synthesizing electron-rich transition-metal complexes for the activation of inert bonds. However, this type of pincer ligand and complexes thereof have remained elusive owing to their challenging synthesis. We herein describe the first synthesis of a CSiC pincer ligand scaffold through the coupling of a silyl-NHC chelate with a benzyl-NHC chelate induced by one-electron oxidation in the coordination sphere of a cobalt complex...
March 1, 2017: Angewandte Chemie
Mathias Mastalir, Karl Kirchner
ABSTRACT: Kumada-Corriu and Negishi cross-coupling reactions, catalyzed efficiently by a Ni(II) PNP pincer complex containing a triazine backbone, are described. The catalyst is able to react with both activated and inactivated aryl halides including chlorides as well as phenol derivatives such as tosylates and mesylates to give the corresponding cross-coupling products in good to excellent isolated yields. A high diversity of substrates was tested under moderate conditions for both types of reactions...
2017: Monatshefte Für Chemie
Tao Xu, Matthew D Wodrich, Rosario Scopelliti, Clemence Corminboeuf, Xile Hu
Lactate racemase is the first enzyme known to possess a metal pincer active site. The enzyme interconverts d- and l-lactic acid, which is important for the assembly of cell walls in many microorganisms. Here, we report a synthetic model of the active site of lactate racemase, which features a pyridinium-based SCS pincer ligand framework bound to nickel. The model complex mediates the dehydrogenation of alcohols, a reaction relevant to lactate racemization. Experimental and computational data indicate ligand participation in the dehydrogenation reaction...
February 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jacob Neumann, Saravanakumar Elangovan, Anke Spannenberg, Kathrin Junge, Matthias Beller
A novel lutidine based manganese PNP pincer complex has been synthesized for the selective N methylation of aromatic amines with methanol. Using borrowing hydrogen methodology a selection of different functionalized aniline derivatives is methylated selectively in good yields.
January 20, 2017: Chemistry: a European Journal
Subrata Chakraborty, Gregory Leitus, David Milstein
The first example of a base-metal-catalyzed homogeneous hydrogenative coupling of nitriles and amines to selectively form secondary cross-imines is reported. The reaction is catalyzed under mild conditions by a well-defined (iPr-PNP)Fe(H)Br(CO) pincer pre-catalyst and catalytic tBuOK.
January 12, 2017: Angewandte Chemie
Nicklas Deibl, Rhett Kempe
The development of catalytic reactions for synthesizing different compounds from alcohols to save fossil carbon feedstock and reduce CO2 emissions is of high importance. Replacing rare noble metals with abundantly available 3d metals is equally important. We report a manganese-complex-catalyzed multicomponent synthesis of pyrimidines from amidines and up to three alcohols. Our reaction proceeds through condensation and dehydrogenation steps, permitting selective C-C and C-N bond formations. β-Alkylation reactions are used to multiply alkylate secondary alcohols with two different primary alcohols to synthesize fully substituted pyrimidines in a one-pot process...
January 12, 2017: Angewandte Chemie
Jeffrey A Therrien, Michael O Wolf
The effect of modifying the pyridyl para position of lutidine-linked bis(N-heterocyclic carbene) Pd pincer complexes is studied both experimentally (R = OMe, H, Br, and COOR) and computationally, showing a strong effect on the first reduction potential of the complex and allowing the reduction potential to be tuned over a wide range in relation to the Hammett σp constant of the para substituent. The effect of the pyridyl para substituent on electron density of the metal center, frontier orbital energies, and dissociation energy of the trans ligand are also investigated in the context of reactivity with CO2 through electrochemical characterization of the complexes under N2 and CO2 and controlled potential electrolysis experiments where CO2 is reduced to CO...
January 10, 2017: Inorganic Chemistry
Stacey A Morris, Dmitry G Gusev
Pincer-type complexes [OsH2 (CO){PyCH2 NHCH2 CH2 NHPtBu2 }] and [OsH2 (CO){HN(CH2 CH2 PiPr2 )2 }] catalyze the disproportionation reaction of aldehydes via an outer-sphere bifunctional mechanism achieving turnover frequencies up to 14 000 h(-1) . The N-H group of the catalysts is a key player in this process, elucidated with the help of DFT calculations.
January 9, 2017: Angewandte Chemie
Fernando Comba, Carlos Yacuzzi, Pablo J Ali, Gerardo Zanotti, Martin Buttaro, Francisco Piccaluga
BACKGROUND: The purpose of this study is to evaluate the clinical outcomes, radiological degenerative progression and the joint preservation rate in a series of patients with Femoroacetabular Impingement (FAI) treated with hip arthroscopy at a minimum follow-up of 7 years. The predictive factors for total hip arthroplasty (THA) requirement were analyzed. MATERIALS AND METHODS: Between February 2008 and February 2009, 42 consecutive patients treated with hip arthroscopy due to FAI syndrome were included...
July 2016: Muscles, Ligaments and Tendons Journal
Yan-Zhi Liu, Kun Yuan, Liu Liu, Zhao Yuan, Yuan-Cheng Zhu
Anion recognitions between common anions and a novel pincer-like receptor (N,N'-bis(5-fluorobenzoyloxyethyl)urea, BFUR) were theoretically explored, particularly on geometric features of the BFUR@X (X = F(-), Cl(-), Br(-), I(-), CO3(2-), NO3(-), and SO4(2-)) systems at a molecular level in this work. Complex structures show that two N-H groups as a claw and two -C6F5 rings on BFUR as a pair of tweezers simultaneously interact with captured anions through cooperative double-dentate hydrogen bond and double-side anion-π interactions...
January 23, 2017: Journal of Physical Chemistry. A
Robert H Crabtree
The different types of acceptorless alcohol dehydrogenation (AAD) reactions are discussed, followed by the catalysts and mechanisms involved. Special emphasis is put on the common appearance in AAD of pincer ligands, of noninnocent ligands, and of outer sphere mechanisms. Early work emphasized precious metals, mainly Ru and Ir, but interest in nonprecious metal AAD catalysis is growing. Alcohol-amine combinations are discussed to the extent that net oxidation occurs by loss of H2. These reactions are of potential synthetic interest because they can lead to N heterocycles such as pyrroles and pyridines...
January 4, 2017: Chemical Reviews
Yulei Wang, Chuan Qin, Xiangqing Jia, Xuebing Leng, Zheng Huang
A unique Ir complex ((tBu) NC(C) P)Ir with the pyridine-phosphine pincer as the sole ligand, featuring a dual agostic interaction between the Ir and two σ C-H bonds from a tBu substituent, has been prepared. This complex exhibits exceptionally high activity and excellent regio- and stereoselectivity for monoisomerization of 1-alkenes to trans-2-alkenes with wide functional-group tolerance. Reactions can be performed in neat reactant on a more than 100 gram scale using 0.005 mol % catalyst loadings with turnover numbers up to 19000...
January 2, 2017: Angewandte Chemie
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"