pinecone/core-2020-05-10-deduplication huggingface dataset:
Visible-Light Photoredox Catalysis in Flow

Photoredox catalysis: A variety of organic transformations mediated by visible-light-active photoredox catalysts have been conducted in a photochemical flow reactor. The reactor design is very simple and can be easily implemented in any laboratory (see picture). In addition, this reactor afforded a marked increase in the reaction rate compared to those observed in typical batch (round bottom flask) reactors.National Science Foundation (U.S.) (Grant CHE-1056568)National Institutes of Health (U.S.) (NIGMS Grant R01-GM096129)Alfred P. Sloan FoundationAmgen Inc.Boehringer Ingelheim PharmaceuticalsAmgen Inc. (Graduate Fellowship)NMR (CHE-0619339)MS (CHE-0443618
A Bulky Biaryl Phosphine Ligand Allows for Palladium-Catalyzed Amidation of Five-Membered Heterocycles as Electrophiles

The incredible bulk: The first palladium-catalyzed amidation of five-membered heterocyclic bromides with multiple heteroatoms was achieved using the Pd/1 catalyst system. N-Arylated imidazoles, pyrazoles, thiazoles, pyrroles, and thiophenes were synthesized in moderate to excellent yield. Experimental results and DFT calculations point to the need for an electron-rich and sterically demanding biaryl phosphine ligand to promote these difficult reactions.National Institutes of Health (U.S.) (Grant GM58160)National Science Foundation (U.S.) (Grant CHE9808061)National Science Foundation (U.S.) (Grant DBI 9729592)National Science Foundation (U.S.) (CHE-0946721
The Rate of Charge Tunneling through Self-Assembled Monolayers Is Insensitive to Many Functional Group Substitutions

Insensitivity: A series of molecules containing a common head group and body as well as structurally varied tail groups (-R) has been used in junctions with the structure Ag/S(CH2)4CONH(CH2)2R//Ga2O3/EGaIn to study the rates of charge transport by tunneling. Changing the structure of R over a range of common aliphatic, aromatic, and heteroaromatic organic groups was found to not significantly influence the rate of tunneling (see plots; the dashed lines represent calibration standards).Chemistry and Chemical Biolog
DNA Self-Assembly of Targeted Near-Infrared-Responsive Gold Nanoparticles for Cancer Thermo-Chemotherapy

Targeted cancer therapy: Inspired by the ability of DNA hybridization, a targeted near-infrared (NIR) light-responsive delivery system has been developed through simple DNA self-assembly (see picture; PEG=polyethylene glycol). This DNA-based platform shows the ability of releasing therapeutics upon near-infrared irradiation, and remarkable targeted thermo- and chemotherapeutic efficacy in vitro and in vivo.National Institutes of Health (U.S.) (Grant CA151884)Prostate Cancer Foundation (Program in Cancer Nanotherapeutics
Mechanical Drawing of Gas Sensors on Paper

Pencil it in: Mechanical abrasion of compressed single-walled carbon nanotubes (SWCNTs) on the surface of paper produces sensors capable of detecting NH[subscript 3] gas at sub-ppm concentrations. This method of fabrication is simple, inexpensive, and entirely solvent-free, and avoids difficulties arising from the inherent instability of many SWCNT dispersions.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-07-D-004)National Institutes of Health (U.S.) (National Cancer Institute (U.S.) Postdoctoral Fellowship Grant F32A1571997
Effective fixation of CO2 by iridium-catalyzed hydrosilylation

CO2 as feedstock: An air- and moisture-stable iridium(III) catalyst effectively promotes the hydrosilylation of CO2. This reaction leads to silyl formate in a highly selective manner and proceeds efficiently under mild conditions, most likely by an outer-sphere mechanism, as suggested by theoretical calculations. Copyright Â© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Financial support from MINECO/FEDER (CTQ2010-15221, CSD2009-00050 CONSOLIDER-INGENIO 2010, CTQ2011-27593, “Ramon y Cajal” (P.J.S.M.) and “Juan de la Cierva” (M.I.) programs), and DGA/FSE (group E7), is acknowledged.Peer Reviewe
Introduction of Fluorine and Fluorine-Containing Functional Groups

Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo- and transition-metal catalysis. The most challenging transformation remains the formation of the parent C[BOND]F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal—fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost-efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.Chemistry and Chemical Biolog
Why Silver Deposition is so Fast: Solving the Enigma of Metal Deposition

A perfect match: Silver deposition is one of the fastest electrochemical reactions, even though the Ag+ ion loses more than 5 eV solvation energy in the process. This phenomenon, an example of the enigma of metal deposition, was investigated by a combination of MD simulations, DFT, and specially developed theory. At the surface, the Ag+ ion experiences a strong interaction with the sp band of silver, which catalyzes the reaction.Fil: Pinto, Leandro M. C.. Universidade Estadual Paulista Julio de Mesquita Filho. Facultad de Filosofia E Ciencias-campus de Marilia; Brasil. Universitat Ulm; AlemaniaFil: Spohr, Eckhard. Universitat Duisburg - Essen; AlemaniaFil: Quaino, Paola Monica. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Electroquímica Aplicada E Ingeniería Electroquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; ArgentinaFil: Santos, Elizabeth del Carmen. Universitat Ulm; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Instituto de Física "Enrique Gaviola"; ArgentinaFil: Schmickler, Wolfgang. Institute Of Theoretical Chemistry; Alemania. Universitat Ulm; Alemani
メン　フセイ　シクロペンタジエニルルテニウム　サクタイ　ヲ　モチイタ　シンキ　フセイ　アリル　イチカン　ハンノウ　ト　フセイ　ジュウゴウ　ハンノウ　二　カンスル　ケンキュウ

This is the author's version of a work that was accepted for publication in Angewandte Chemie International Edition. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms, may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Angewandte Chemie International Edition, 52(18), 2013, DOI: 10.1002/anie.20130239
Enzymatic “Click” Ligation: Selective Cysteine Modification in Polypeptides Enabled by Promiscuous Glutathione S-Transferase

Singled out for special treatment: Naturally occurring glutathione S-transferase (GST) was used to catalyze an efficient “click” ligation between polypeptides with an N-terminal glutathione sequence and biomolecules or chemical probes containing perfluorinated aromatic groups (see scheme). The site-specific modification of one cysteine residue was possible in the presence of other unprotected cysteine residues and reactive functional groups.National Institutes of Health (U.S.) (GM101762)National Institutes of Health (U.S.) (Award GM46059)MIT Faculty Start-up FundDamon Runyon Cancer Research FoundationAmgen Inc. (Summer Graduate Research Fellowship
Tailoring Chimeric Ligands for Studying and Biasing ErbB Receptor Family Interactions

Described is the development and application of a versatile semisynthetic strategy, based on a combination of sortase-mediated coupling and tetrazine ligation chemistry, which can be exploited for the efficient incorporation of tunable functionality into chimeric recombinant proteins. To demonstrate the scope of the method, the assembly of a set of bivalent ligands, which integrate members of the epidermal growth factor (EGF) ligand family, is described. By using a series of bivalent EGFs with variable intraligand spacing, the differences in structure were correlated with the ability to bias signaling in the ErbB receptor family in a cell motility assay. Biasing away from EGFR-HER2 dimerization with a bivalent EGF was observed to reduce cell motility in an intraligand distance-dependent fashion, thus demonstrating the utility of the approach for acutely perturbing receptor-mediated cell signaling pathways.National Cancer Institute (U.S.). Integrative Cancer Biology Program (Grant U54-CA112967)National Institutes of Health (U.S.) (R01DE019523-13)Massachusetts Institute of Technology. Computational and Systems Biology Program. MIT-Merck Postdoctoral FellowshipSwiss National Science Foundation (Postdoctoral Fellowship)National Institute of Environmental Health Sciences (Training Grant in Environmental Toxicology 5-T32-ES007020
Nickel-Catalyzed Mizoroki-Heck Reaction of Aryl Sulfonates and Chlorides with Electronically Unbiased Terminal Olefins: High Selectivity for Branched Products

Achieving high selectivity in the Heck reaction of electronically unbiased alkenes has been a longstanding challenge. Using a nickel-catalyzed cationic Heck reaction, we were able to achieve excellent selectivity for branched products (≥19:1 in all cases) over a wide range of aryl electrophiles and aliphatic olefins. A bidentate ligand with a suitable bite angle and steric profile was key to obtaining high branched/linear selectivity, whereas the appropriate base suppressed alkene isomerization of the product. Although aryl triflates are traditionally used to access the cationic Heck pathway, we have shown that, by using triethylsilyl trifluoromethanesulfonate, we can effect a counterion exchange of the catalytic nickel complex, such that cheaper and more stable aryl chlorides, mesylates, tosylates, and sulfamates can be used to yield the same branched products with high selectivity.National Institute of General Medical Sciences (U.S.) (NIGMS (GM62755))National Institutes of Health (U.S.) (NIH Postdoctoral Fellowship)National Science Foundation (U.S.) (NSF Graduate Research Fellowship
Synthesis and catalytic activities of porphyrin-based PCP pincer complexes.

2, 18-Bis(diphenylphosphino)porphyrins undergo peripheral cyclometalation with group 10 transition-metal salts to afford the corresponding porphyrin-based PCP pincer complexes. The porphyrinic plane and the PCP-pincer unit are apparently coplanar, with small strain. The catalytic activities of the porphyrin-based pincer complexes at the periphery were investigated in the allylation of benzaldehyde with allylstannane and in the 1, 4-reduction of chalcone to discover the electronic interplay between the inner metal and the outer metal in catalysis
Rational Perturbation of the Fluorescence Quantum Yield in Emission‐Tunable and Predictable Fluorophores (Seoul‐Fluors) by a Facile Synthetic Method Involving C—H Activation†

Abstract Fluorescence imaging enables the uniquely sensitive observation of functional‐ and molecular‐recognition events in living cells. However, only a limited range of biological processes have been subjected to imaging because of the lack of a design strategy and difficulties in the synthesis of biosensors. Herein, we report a facile synthesis of emission‐tunable and predictable Seoul‐Fluors, 9‐aryl‐1,2‐dihydrolopyrrolo[3,4‐b]indolizin‐3‐ones, with various R1 and R2 substituents by coinage‐metal‐catalyzed intramolecular 1,3‐dipolar cycloaddition and subsequent palladium‐mediated C—H activation. We also showed that the quantum yields of Seoul‐Fluors are controlled by the electronic nature of the substituents, which influences the extent of photoinduced electron transfer. On the basis of this understanding, we demonstrated our design strategy by the development of a Seoul‐Fluor‐based chemosensor 20 for reactive oxygen species that was not accessible by a previous synthetic route
Chemical synthesis, 3D structure and ASIC binding site of mambalgin-2

Mambalgins are a novel class of snake venom components that exert potent analgesic effects mediated through the inhibition of acid-sensing ion channels (ASICs). The 57-residue polypeptide mambalgin-2 (Ma-2) was synthesized by using a combination of solid-phase peptide synthesis and native chemical ligation. The structure of the synthetic toxin, determined using homonuclear NMR, revealed an unusual three-finger toxin fold reminiscent of functionally unrelated snake toxins. Electrophysiological analysis of Ma-2 on wild-type and mutant ASIC1a receptors allowed us to identify -helix 5, which borders on the functionally critical acidic pocket of the channel, as a major part of the Ma-2 binding site. This region is also crucial for the interaction of ASIC1a with the spider toxin PcTx1, thus suggesting that the binding sites for these toxins substantially overlap. This work lays the foundation for structure-activity relationship (SAR) studies and further development of this promising analgesic peptide
Organozinc pivalate reagents : segregation, solubility, stabilisation and structural insights

The pivalates RZnOPiv⋅Mg(OPiv)X⋅n LiCl (OPiv=pivalate; R=aryl; X=Cl, Br, I) stand out amongst salt-supported organometallic reagents, because apart from their effectiveness in Negishi cross-coupling reactions, they show more resistance to attack by moist air than conventional organometallic compounds. Herein a combination of synthesis, coupling applications, X-ray crystallographic studies, NMR (including DOSY) studies, and ESI mass spectrometric studies provide details of these pivalate reagents in their own right. A p-tolyl case system shows that in [D8]THF solution these reagents exist as separated Me(p-C6H4)ZnCl and Mg(OPiv)2 species. Air exposure tests and X-ray crystallographic studies indicate that Mg(OPiv)2 enhances the air stability of aryl zinc species by sequestering H2O contaminants. Coupling reactions of Me(p-C6H4)ZnX (where X=different salts) with 4-bromoanisole highlight the importance of the presence of Mg(OPiv)2. Insight into the role of LiCl in these multicomponent mixtures is provided by the molecular structure of [(THF)2Li2(Cl)2(OPiv)2Zn]
Quantitative analysis of location- and sequence-dependent deamination by APOBEC3G using real-time NMR spectroscopy.

NMR法を用いた実時間追跡で抗エイズウイルス酵素反応の定量解析に成功 -新規抗エイズウイルス薬創製に期待-. 京都大学プレスリリース. 2014-01-29.The human antiretroviral factor APOBEC3G (A3G) deaminates the newly synthesized minus strand of the human immunodeficiency virus 1 (HIV-1), which results in the abolition of the infectivity of virus-infectivity-factor (Vif)-deficient HIV-1 strains.1-6 A unique property of A3G is that it deaminates a CCC hot spot that is located close to the 5' end more effectively than one that is less close to the 5' end. However, the mechanism of this process is elusive as it includes nonspecific binding of A3G to DNA and sliding of A3G along the DNA strand. Therefore, this process cannot be analyzed by existing methods using the Michaelis-Menten theory. A new real-time NMR method has been developed to examine the nonspecific binding and the sliding processes explicitly, and it was applied to the analysis of the deamination by A3G. As a result, the location-dependent deamination can be explained by a difference in the catalytic rates that depend on the direction of the approach of A3G to the target cytidine. Real-time NMR experiments also showed that A3G deaminates CCCC tandem hotspots with little redundancy, which suggests that A3G efficiently mutates many CCC hotspots that are scattered throughout the HIV-1 genome
Total Synthesis of the Antimitotic Marine Macrolide (−)-Leiodermatolide

Leiodermatolide is an antimitotic macrolide isolated from the marine sponge Leiodermatium sp. whose potentially novel tubulin-targeting mechanism of action makes it an exciting lead for anticancer drug discovery. In pursuit of a sustainable supply, we report a highly stereocontrolled total synthesis (3.2 % yield) based on a convergent sequence of palladium-mediated fragment assembly and macrolactonization. Boron-mediated aldol reactions were used to configure the three key fragments 2, 5, and 6 by employing the appropriate enantiomer of the lactate-derived ketone 7.This research was supported by a SCAST postgraduate research
scholarship (K.K.-H.N.), the Todd-Raphael Fund (S.W.), and Clare
College, Cambridge (S.M.D.). We thank Dr. Amy Wright (HBOI,
Florida Atlantic University) for helpful discussions and the EPSRC
UK National Mass Spectrometry Facility at Swansea University.This is the final published version. It's also available from Wiley at http://onlinelibrary.wiley.com/doi/10.1002/anie.201310164/abstract
Boron Clusters as Highly Stable Magnesium‐Battery Electrolytes

Boron clusters are proposed as a new concept for the design of magnesium‐battery electrolytes that are magnesium‐battery‐compatible, highly stable, and noncorrosive. A novel carborane‐based electrolyte incorporating an unprecedented magnesium‐centered complex anion is reported and shown to perform well as a magnesium‐battery electrolyte. This finding opens a new approach towards the design of electrolytes whose likelihood of meeting the challenging design targets for magnesium‐battery electrolytes is very high.     A b(o)rilliant improvement : An electrolyte incorporating an unprecedented magnesium‐centered complex anion was developed for use in rechargeable magnesium batteries. The carboranyl magnesium halide (see structure; B purple, Cl green, O red, C white, Mg orange) exhibited compatibility with magnesium‐metal anodes as well as remarkable oxidative stability (3.2 V vs. Mg) on non‐noble‐metal electrodes
Crystal structures of the carborane dianions, [1,4-(PhCB10H10C)2C6H4]2- and [1,4-(PhCB10H10C)2C6F4]2-, and the stabilizing role of the para-phenylene unit on unusual 2n+3 SE clusters.

While carboranes with 2 n+2 and 2 n+4 (n=number of skeletal atoms) skeletal electrons (SE) are widely known, little has been reported on carboranes with odd SE numbers. Electrochemical measurements on two-cage assemblies, where two C-phenyl-ortho-carboranyl groups are linked by a para-phenylene or a para-tetrafluorophenylene bridge, revealed two well separated and reversible two-electron reduction waves indicating formation of stable dianions and tetraanions. The salts of the dianions were isolated by reduction with sodium metal and their unusual structures were determined by X-ray crystallography. The diamagnetic dianions contain two 2 n+3 SE clusters where each cluster has a notably long carborane C–carborane C distance of ca 2.4 Å. The π conjugation within the phenylene bridge plays an important role in the stabilization of these carboranes with odd SE counts
Chemically Orthogonal Three‐Patch Microparticles

Compared to two‐dimensional substrates, only a few methodologies exist for the spatially controlled decoration of three‐dimensional objects, such as microparticles. Combining electrohydrodynamic co‐jetting with synthetic polymer chemistry, we were able to create two‐ and three‐patch microparticles displaying chemically orthogonal anchor groups on three distinct surface patches of the same particle. This approach takes advantage of a combination of novel chemically orthogonal polylactide‐based polymers and their processing by electrohydrodynamic co‐jetting to yield unprecedented multifunctional microparticles. Several micropatterned particles were fabricated displaying orthogonal click functionalities. Specifically, we demonstrate novel two‐ and three‐patch particles. Multi‐patch particles are highly sought after for their potential to present multiple distinct ligands in a directional manner. This work clearly establishes a viable route towards orthogonal reaction strategies on multivalent micropatterned particles.     Patchwork family : Three‐patch microparticles (see scheme) containing functionalized poly(lactide) derivatives in select compartments were fabricated through the electrohydrodynamic (EHD) co‐jetting process. The microparticles were characterized by Raman confocal microspectroscopy and the bio‐orthogonal surface modification of each patch was demonstrated
The role of ligand-field states in the ultrafast photophysical cycle of the prototypical iron(II) spin-crossover compound [Fe(ptz)6](BF4)2

International audienceLight-induced excited spin-state trapping (LIESST) in iron(II) spin-crossover compounds, that is, the light-induced population of the high-spin (S=2) state below the thermal transition temperature, was discovered thirty years ago. For irradiation into metal-ligand charge transfer (MLCT) bands of the low-spin (S=0) species the acknowledged sequence takes the system from the initially excited 1MLCT to the high-spin state via the 3MLCT state within ca. 150 fs, thereby bypassing low-lying ligand-field (LF) states. Nevertheless, these play a role, as borne out by the observation of LIESST and reverse-LIESST on irradiation directly into the LF bands for systems with only high-energy MLCT states. Herein we elucidate the ultrafast reverse-LIESST pathway by identifying the lowest energy S=1 LF state as an intermediate state with a lifetime of 39 ps for the light-induced high-spin to low-spin conversion on irradiation into the spin-allowed LF transition of the high-spin species in the NIR
Structural Reevaluation of the Electrophilic Hypervalent Iodine Reagent for Trifluoromethylthiolation Supported by the Crystalline Sponge Method for X-ray Analysis

Hypervalent iodine λ[superscript 3]-benziodoxoles are common electrophilic transfer reagents known for their enhanced stability compared to their non-cyclic analogues. Herein we present data showing that chlorobenziodoxole reacts with two different thiolate nucleophiles (thiocyanate and trifluoromethylthiolate), resulting in the formation of stable thioperoxy complexes rather than the expected benziodoxole derivatives. We further report a revised structure for the earlier described electrophilic trifluoromethylthiolation reagent (1), which was previously believed to contain the benziodoxole framework. Our findings, which are based on a combination of analytical techniques, including the recently introduced crystalline sponge method for X-ray analysis, unambiguously demonstrate that 1 is a thioperoxy compound both in solution and the solid state.National Institutes of Health (U.S.) (Award GM58160
Substrate Activity Screening with Kinases: Discovery of Small‐Molecule Substrate‐Competitive c‐Src Inhibitors

Substrate‐competitive kinase inhibitors represent a promising class of kinase inhibitors, however, there is no methodology to selectively identify this type of inhibitor. Substrate activity screening was applied to tyrosine kinases. By using this methodology, the first small‐molecule substrates for any protein kinase were discovered, as well as the first substrate‐competitive inhibitors of c‐Src with activity in both biochemical and cellular assays. Characterization of the lead inhibitor demonstrates that substrate‐competitive kinase inhibitors possess unique properties, including cellular efficacy that matches biochemical potency and synergy with ATP‐competitive inhibitors.     SASsy inhibitors : Small‐molecule substrate‐competitive inhibitors of the tyrosine kinase c‐Src were discovered through the application of substrate activity screening (SAS). Characterization of the lead inhibitor demonstrates that substrate‐competitive kinase inhibitors possess unique properties, including cellular efficacy that matches biochemical potency and synergy with ATP‐competitive inhibitors