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https://www.readbyqxmd.com/read/28544744/structural-basis-for-copper-oxygen-mediated-c-h-bond-activation-by-the-formylglycine-generating-enzyme
#1
Marcel Meury, Matthias Knop, Florian P Seebeck
The formylglycine-generating enzyme (FGE) is a unique copper-protein that catalyzes oxygen-dependent C-H activation. We describe 1.66 Å- and 1.28 Å-resolution crystal structures of FGE from Thermomonospora curvata in complex with either Ag (I) or Cd (II) providing definitive evidence for a high-affinity metal-binding site in this enzyme. The structures reveal a bis-cysteine linear coordination of the monovalent metal, and tetrahedral coordination of the bivalent metal. Similar coordinational change may occur in the active enzyme as a result of Cu (I)/(II) redox cycling...
May 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544634/hydrogen-bond-driven-self-assembly-between-amidinium-cations-and-carboxylate-anions-a-combined-molecular-dynamics-nmr-spectroscopy-and-single-crystal-x-ray-diffraction-study
#2
Michael Thomas, Thomas Anglim Lagones, Martyna Judd, Mahbod Morshedi, Megan L O'Mara, Nicholas G White
A combination of molecular dynamics (MD), NMR spectroscopy, and single crystal X-ray diffraction (SCXRD) techniques was used to probe the self-assembly of para- and meta-bis(amidinium) compounds with para-, meta-, and ortho-dicarboxylates. Good concordance was observed between the MD and experimental results. In DMSO solution, the systems form several rapidly exchanging assemblies, in part because a range of hydrogen bonding interactions is possible between the amidinium and carboxylate moieties. Upon crystallization, the majority of the systems form 1D supramolecular polymers, which are held together by short N-H⋅⋅⋅O hydrogen bonds...
May 23, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28544561/monofluoromethyl-substituted-sulfonium-ylides-electrophilic-monofluoromethylating-reagents-with-broad-substrate-scopes
#3
Yafei Liu, Long Lu, Qilong Shen
Two electrophilic monofluoromethylating reagents S-monofluoromethyl-S-phenyl-bis(carbomethoxy) methylide sulfonium ylide 3a and S-monofluoromethyl-S-(4-nitrophenyl)-bis(carbo -methoxy) methylide sulfonium ylide 3b and their reactions with a variety of nucleophiles such as alcohols and malonate derivatives, sulfonic and carboxylic acids, phenols, amides, and nitrogen of heteroarenes under mild conditions were described. Mechanistic studies by employing deuterated reagents 3a-D2/3b-D2 suggest that these monofluoromethylating reactions proceed via an electrophilic substitution pathway...
May 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544372/deprotonation-of-a-seemingly-hydridic-diborane-6-to-build-a-b-b-bond
#4
Thomas Kaese, Hendrik Budy, Michael Bolte, Hans-Wolfram Lerner, Matthias Wagner
Deprotonation of the doubly arylene-bridged diborane(6) derivative 1H2 with (Me3 Si)3 CLi or (Me3 Si)2 NK gives the B-B σ-bonded species M[1H] in essentially quantitative yields (THF, room temperature; M=Li, K, arylene=4,4'-di-tert-butyl-2,2'-biphenylylene). With nBuLi as the base, the yield of Li[1H] drops to 20 % and the 1,1-bis(9-borafluorenyl)butane Li[2H] is formed as a side product (30 %). In addition to the 1,1-butanediyl fragment, the two boron atoms of Li[2H] are linked by a μ-H bridge. In the closely related molecule Li[3H], the corresponding μ-H atom can be abstracted with (Me3 Si)3 CLi to afford the B-B-bonded conjugated base Li2 [3] (THF, 150 °C; 15 %)...
May 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28544072/morphological-control-of-heteroleptic-cis-and-trans-pd2-l2-l-2-cages
#5
Witold M Bloch, Julian J Holstein, Wolf Hiller, Guido H Clever
Control over the integrative self-sorting of metallo-supramolecular assemblies opens up possibilities for introducing increased complexity and function into a single self-assembled architecture. Herein, the relationship between the geometry of three ligand components and morphology of three self-sorted heteroleptic [Pd2 L2 L'2 ](4+) cages is examined. Pd-mediated assembly of two bis-monodentate pyridyl ligands with native bite angles of 75° and 120° affords a cis-[Pd2 L2 L'2 ](4+) cage while the same reaction with two ligands with bite angles of 75° and 60° gives an unprecedented, self-penetrating structural motif; a trans-[Pd2 (anti-L)2 L'2 ](4+) heteroleptic cage with a "doubly bridged figure eight" topology...
May 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28543845/noninnocent-%C3%AE-diiminate-ligands-redox-activity-of-a-bis-alkylimidazole-methane-ligand-in-cobalt-and-zinc-complexes
#6
Pradip Ghosh, Richard Naastepad, Charl F Riemersma, Martin Lutz, Marc-Etienne Moret, Robertus Johannes Klein Gebbink
A new β-diiminate ligand (the bis(1-methyl-4,5-diphenyl-1H-imidazol-2-yl)methane anion, L-) is introduced, in which the ligand framework bears an extended imidazole-based π-system in conjugation with a formal NacNac backbone. Bis-ligated transition metal complexes (Co, Zn) featuring this anionic ligand undergo a series of four consecutive single-electron oxidations that are all ligand based. The singly and doubly oxidized complexes can be synthesized on a preparative scale and have been fully characterized by various spectroscopic techniques...
May 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28543768/an-efficient-pd-catalyzed-regio-and-stereoselective-carboxylation-of-allylic-alcohols-with-formic-acid
#7
Yao Fu, Rui Shang, Ming-Chen Fu, Wan-Min Cheng
Formic acid is efficiently used as a C1 source to directly carboxylate allylic alcohols in the presence of a low loading of palladium catalyst and acetic anhydride as additive to afford β,γ-unsaturated carboxylic acids with excellent chemo-, regio-, and stereoselectivity. The reaction proceeds through a carbonylation process with in situ-generated carbon monoxide (CO) under mild conditions, avoiding the use of high-pressure gaseous CO. A bisphosphine ligand that has a large bite angle (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) was found to be uniquely effective for this transformation...
May 25, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28543642/bidirectional-superior-cavopulmonary-anastomosis-with-or-without-cardiopulmonary-bypass-a-randomized-study
#8
Sachin Talwar, Anish Gupta, Ashima Nehra, Neeti Makhija, Poonam Malhotra Kapoor, Vishnubhatla Sreenivas, Shiv Kumar Choudhary, Balram Airan
OBJECTIVES: This study aims to compare the bidirectional superior cavopulmonary anastomosis (BDG) with or without cardiopulmonary bypass (CPB). METHODS: 100 patients undergoing BDG were randomized into two groups: Off-CPB or on-CPB groups. All patients underwent near-infrared spectrophotometry (NIRS) and bispectral index (BIS) monitoring and pre- and postoperative serum 100 beta protein measurements (Sβ100) and neuro-cognitive evaluation. Postoperative intensive care unit (ICU) parameters were also studied...
May 21, 2017: Journal of Cardiac Surgery
https://www.readbyqxmd.com/read/28543444/mechanistic-studies-on-the-peroxyoxalate-chemiluminescence-using-sodium-salicylate-as-base-catalyst
#9
Glalci A Souza, André P Lang, Wilhelm J Baader
Mechanistic studies on the peroxyoxalate chemiluminescence are often conducted with imidazole as base and nucleophilic catalyst. However, it is also known that this compound, at high concentrations, leads to a drastic reduction of the chemiluminescence quantum yields, apparently due the destruction of the high-energy intermediate. Consequently, the search for new catalysts for this transformation is of importance for mechanistic studies as well as analytical application. Therefore, we report here a study on the mechanism of the peroxyoxalate reaction with sodium salicylate as base catalyst; which has already been utilized in this reaction, however, no detailed mechanistic investigation is known...
May 23, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28541944/possibilities-of-chromium-iii-separation-from-acid-solution-using-the-double-carrier-supported-liquid-membrane-dcslm
#10
Jakub Rajewski, Paulina Rajewska
This paper describes the problem of recovery and reusing chromium from aqueous solutions. The authors studied a novel double-carrier supported liquid membrane system (DCSLM) with di(2-ethylhexyl) phosphoric acid (D2EHPA) and bis(2,4,4-trimethyl) phosphinic acid (Cyanex272) as a carrier of Cr(III) ions as a method to separate chromium (III) from acid solutions. As a result, they confirmed that the presence of two carriers in the DCSLM with the most effective carrier concentration ratios, leads to approximately three times shorter pertraction, compared to a process conducted with the D2EHPA only...
May 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28541704/asymmetric-synthesis-of-amino-bis-pyrazolone-derivatives-via-an-organocatalytic-mannich-reaction
#11
Pankaj Chauhan, Suruchi Mahajan, Ugur Kaya, Anssi Peuronen, Kari Rissanen, Dieter Enders
A new series of N-Boc ketimines derived from pyrazolin-5-ones have been used as electrophiles in asymmetric Mannich reactions with pyrazolones. The amino-bis-pyrazolone products are obtained in excellent yields and stereoselectivities by employing a very low loading of 1 mol% of a bifunctional squaramide organocatalyst. Depending on the substitution in the 4-position of the pyrazolones the new protocol allows for the generation of one or two tetra-substituted stereocenters including a one-pot version combing the Mannich reaction with a base mediated halogenation...
May 25, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28541688/circularly-polarized-luminescence-of-silica-grafted-europium-chiral-derivatives-prepared-through-a-sequential-functionalization
#12
Lidia Armelao, Daniela Belli Dell'Amico, Luca Bellucci, Gregorio Bottaro, Lorenzo Di Bari, Luca Labella, Fabio Marchetti, Simona Samaritani, Francesco Zinna
We describe a new organic/inorganic material emitting circularly polarized luminescence (CPL). The hybrid system was obtained by the following steps: (i) preliminary grafting of the europium N,N-dibutylcarbamate [Eu(O2CNBu2)3] complex onto silica, (ii) substitution of the residual carbamato groups with anionic 1,3-diphenyl-1,3-propanedionato ligands (dbm), and (iii) subsequent introduction of the neutral tridentate chiral ligand 2,6-bis(isopropyl-2-oxazolin-2-yl)pyridine ((i)Pr-PyBox) in the metal coordination sphere...
May 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28541672/impacts-of-unregulated-novel-brominated-flame-retardants-on-human-liver-thyroid-deiodination-and-sulfotransferation
#13
Tristan Alexander Smythe, Craig M Butt, Heather M Stapleton, Kerri Pleskach, Geemitha Ratnayake, Chae Yoon Song, Nicole Riddell, Alex Konstantinov, Gregg Thomas Tomy
The inhibitory effects of five novel brominated flame retardants: 1,2-bis(2,4,5-tribromophenoxy)ethane (BTBPE), decabromodiphenylethane (DBDPE), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB), bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP), and β-tetrabromoethylcyclohexane (β-TBECH) on thyroid hormone deiodinase (DIO) and sulfotransferase (SULT) activity were investigated using human in vitro liver microsomal and cytosolic bioassays. Enzymatic activity was measured by incubating active human liver sub-cellular fractions with thyroid hormones (T4 and rT3 separately) and measuring changes in thyroid hormone (T4, T3, rT3, and 3,3'-T2) concentrations...
May 25, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28541048/monoanionic-bis-pyrazolyl-methylborate-ph3b-ch-3-5-ch3-2pz-2-as-a-supporting-ligand-for-copper-i-ethylene-cis-2-butene-and-carbonyl-complexes
#14
Shawn G Ridlen, Naveen V Kulkarni, H V Rasika Dias
The monoanionic bidentate ligand [(Ph3B)CH(3,5-(CH3)2Pz)2)](-) has been prepared from lithium bis(pyrazolyl)methanide and triphenylborane. This useful new ligand is closely related to the well-established bis(pyrazolyl)borate and bis(pyrazolyl)methane ligands but has key differences to both analogues as well. The ethylene, cis-2-butene, and carbon monoxide adducts [(Ph3B)CH(3,5-(CH3)2Pz)2]Cu(L) (where L = C2H4, cis-CH3HC═CHCH3, and CO) have been prepared from [(Ph3B)CH(3,5-(CH3)2Pz)2)]Li(THF), copper(I) triflate, and the corresponding coligand...
May 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28540372/bis-and-mono-m-benzoic-acid-functionalized-pillar-5-arenes
#15
Xin-Lang Wu, Yi Chen, Wen-Jing Hu, Yahu A Liu, Xue-Shun Jia, Jiu-Sheng Li, Biao Jiang, Ke Wen
Installation of m-benzoic acid functionalities on pillar[5]arene rims resulted in bis- and mono(m-benzoic acid)-functionalized pillar[5]arenes 1 and 2. Bis(m-benzoic acid)-functionalized pillar[5]arene 1 was able to self-assemble to form one-dimensional channels with DMF molecules residing in pillar[5]arene cavities. Esterification of two carboxylic acids in 1 with decane-1,10-diol did not afford a [1]catenane, but a bicyclic compound. Although 1-decanol esterification of mono(m-benzoic acid)-functionalized pillar[5]arene 2 did not form a self-included [1]pseudorotaxane-like structure, a mono(decyl m-benzoate)-functionalized pillar[5]arene bearing an ethyl acetate chain was found to form a self-included complex with the ethyl acetate moiety residing inside the pillar[5]arene cavity...
May 25, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28539727/bioassay-guided-isolation-and-identification-of-antioxidant-flavonoids-from-cyclotrichium-origanifolium-labill-manden-and-scheng
#16
Abdussamat Guzel, Huseyin Aksit, Mahfuz Elmastas, Ramazan Erenler
BACKGROUND: Medicinal and aromatic plants play a significant role in drug discovery and development process. Flavonoids, revealing a wide spectrum of biological activities, extensively found in plants are important secondary metabolites. MATERIALS AND METHODS: Aerial parts of Cyclotrichium origanifolium were collected, dried, and boiled in water then extracted with hexane, ethyl acetate, and n-butanol. Total phenolic content, DPPH(•) scavenging activity, reducing power (FRAP) activity, and ABTS(•+) scavenging activity assays were applied for all extracts...
April 2017: Pharmacognosy Magazine
https://www.readbyqxmd.com/read/28539721/phytochemical-and-biological-evaluations-of-arum-hygrophilum-boiss-araceae
#17
Fatma U Afifi, Violet Kasabri, Simona Litescu, Ismail F Abaza, Khalid Tawaha
BACKGROUND: Arum hygrophilum is a traditional medicinal plant indigenous to Jordan. The present study explores its phytochemistry, antioxidative, antidiabesity, and antiproliferative potentialities. MATERIALS AND METHODS: Column chromatography and HPLC-MS analysis were used for its phytochemical evaluation. Using leaf crude water and ethanol extracts, the antioxidative capacities, their modulation of pancreatic β-cell proliferation, and insulin secretion as well as glucose diffusion and enzymatic bioassays were evaluated...
April 2017: Pharmacognosy Magazine
https://www.readbyqxmd.com/read/28538832/nasalance-scores-of-brazilian-portuguese-speakers-at-5-years-of-age
#18
Débora Natália de Oliveira, Ana Claudia Martins Sampaio-Teixeira, Bianca Gonçalves Alvarenga, Ana Paula Fukushiro, Renata Paciello Yamashita, Inge Elly Kiemle Trindade
Purpose: To determine nasalance scores of Brazilian Portuguese speaking children without evident speech disorders, language delay and orofacial deformities, at age 5 years, and analyze differences between types of speech samples and genders. Methods: Twenty children were analyzed, 11 males, age ranging from 4 years and 10 months to 5 years and 11 months. The Nasometer II 6450 (KayPENTAX) was used for nasalance assessment. Speech samples were eight consonant-vowel syllables and one sequence of nine words...
May 22, 2017: CoDAS
https://www.readbyqxmd.com/read/28537311/naphthodifuran-based-zigzag-type-polycyclic-arene-with-conjugated-side-chains-for-efficient-photovoltaics
#19
Hongjian Peng, Xiangfeng Luan, Liuliu Feng, Jun Yuan, Zhi-Guo Zhang, Yongfang Li, Yingping Zou
Ladder-type conjugated structures with rigid and coplanar molecular frameworks feature longer effective conjugation, affirmative optoelectronic properties and strong intermolecular π-π interactions, which are ideal characteristics for organic photovoltaics. Here, a new "zigzag" angular-fused naphthodifuran (zNDF) based on alkoxyphenyl side chains was designed and synthesized. The distannylated zNDF building block was copolymerized with 4,7-di(5-bromothiophen-2-yl)-5,6-dioctyloxybenzo[c][1,2,5]thiadiazole and 5,8-bis(5-bromothiophen-2-yl)-2,3-bis(4-(2-ethylhexyloxy)-3-fluorophenyl)-6,7-difloroquinoxaline (Br-BT and Br-ffQx) acceptor units by Stille cross coupling reaction to form two new medium bandgap donor-acceptor polymers PzNDFP-BT and PzNDFP-ffQx, respectively...
May 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28537303/palladium-mediated-11-c-carbonylations-using-aryl-halides-and-cyanamide
#20
P Nordeman, S Y Chow, A F Odell, G Antoni, L R Odell
A robust and high-yielding radiochemical synthesis of (11)C-N-cyanobenzamides using a palladium-mediated aminocarbonylation with (11)C-CO, aryl halides and cyanamide is described. The bidentate ligand 1,1'-bis(diphenylphosphino)ferrocene provided (11)C-N-cyanobenzamides from aryl-iodides, bromides, triflates and even chlorides in 28-79% radiochemical yield after semi-preparative HPLC. To further highlight the utility of this method, novel (11)C-N-cyanobenzamide analogs of flufenamic acid, meflanamic acid, dazoxiben and tamibarotene were synthesized in 34-71% radiochemical yields...
May 24, 2017: Organic & Biomolecular Chemistry
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