pinecone/core-2020-05-10-deduplication huggingface dataset:
Separating Para and Ortho Water

Water exists as two nuclear-spin isomers, para and ortho, determined by the
overall spin of its two hydrogen nuclei. For isolated water molecules the
conversion between these isomers is forbidden and they act as different
molecular species. Yet, these species are not readily separable, and little is
known about their specific physical and chemical properties, conversion
mechanisms, or interactions. Here we demonstrate the production of isolated
samples of both spin isomers in pure beams of para and ortho water, with both
species in their respective absolute ground state. These single-quantum-state
samples are ideal targets for unraveling spin-conversion mechanisms, for
precision spectroscopy and fundamental-symmetry-breaking studies, and for
spin-enhanced applications, e. g., laboratory astrophysics and -chemistry or
hypersensitized NMR experiments
Palladium-Templated Subcomponent Self-Assembly of Macrocycles, Catenanes, and Rotaxanes

The reaction of 2,6-diformylpyridine with diverse amines and PdII ions gave rise to a variety of metallosupramolecular species, in which the PdII ion is observed to template a tridentate bis(imino)pyridine ligand. These species included a mononuclear complex as well as [2+2] and [3+3] macrocycles. The addition of pyridine-containing macrocyclic capping ligands allows for topological complexity to arise, thereby enabling the straightforward preparation of structures that include a [2]catenane, a [2]rotaxane, and a doubly threaded [3]rotaxane.This work was underwritten by the Marie Curie Academic-Industrial Initial Training Network on Dynamic Molecular Nanostructures (DYNAMOL) of the European Union’s Seventh Framework Programme (FP7) and the UK Engineering and Physical Sciences Research Council (EPSRC). We thank the Cambridge Chemistry NMR service for experimental assistance, Diamond Light Source (UK) for synchrotron beamtime on I19 (MT7984), and the EPSRC National Crystallography Service for X-ray data collection.This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/anie.20140616
Squeezing, Then Stacking: From Breathing Pores to Three-Dimensional Ionic Self-Assembly under Electrochemical Control

We demonstrate the spontaneous and reversible transition between the two- and three-dimensional self-assembly of a supramolecular system at the solid–liquid interface under electrochemical conditions, using in situ scanning tunneling microscopy. By tuning the interfacial potential, we can selectively organize our target molecules in an open porous pattern, fill these pores to form an auto-host–guest structure, or stack the building blocks in a stratified bilayer. Using a simple electrostatic model, we rationalize which charge density is required to enable bilayer formation, and conversely, which molecular size/charge ratio is necessary in the design of new building blocks. Our results may lead to a new class of electrochemically controlled dynamic host–guest systems, artificial receptors, and smart materialsstatus: publishe
Chemical and structural stability of zirconium-based metal-organic frameworks with large three-dimensional pores by linker engineering

YesThe synthesis of metal–organic frameworks with large three-dimensional channels that are permanently porous and chemically stable offers new opportunities in areas such as catalysis and separation. Two linkers (L1=4,4′,4′′,4′′′-([1,1′-biphenyl]-3,3′,5,5′-tetrayltetrakis(ethyne-2,1-diyl)) tetrabenzoic acid, L2=4,4′,4′′,4′′′-(pyrene-1,3,6,8-tetrayltetrakis(ethyne-2,1-diyl))tetrabenzoic acid) were used that have equivalent connectivity and dimensions but quite distinct torsional flexibility. With these, a solid solution material, [Zr6O4(OH)4(L1)2.6(L2)0.4]⋅(solvent)x, was formed that has three-dimensional crystalline permanent porosity with a surface area of over 4000 m2 g−1 that persists after immersion in water. These properties are not accessible for the isostructural phases made from the separate single linkers.Financial support from EPSRC under EP/H000925, access to the HPC service ARCHER via EP/L000202. S.N. thanks the EU for a Marie Curie fellowship (PIEF-GA-2010-274952). C.M.-G. thanks the Spanish MINECO for a Ramón y Cajal Fellowship (RYC-2012-10894)
Bright, highly water soluble triazacyclononane europium complexes to detect ligand binding with time-resolved FRET microscopy.

Luminescent europium complexes are used in a broad range of applications as a result of their particular emissive properties. The synthesis and application of bright, highly water-soluble, and negatively charged sulfonic- or carboxylic acid derivatives of para-substituted aryl–alkynyl triazacyclononane complexes are described. Introduction of the charged solubilizing moieties suppresses cellular uptake or adsorption to living cells making them applicable for labeling and performing assays on membrane receptors. These europium complexes are applied to monitor fluorescent ligand binding on cell-surface proteins with time-resolved Förster resonance energy transfer (TR-FRET) assays in plate-based format and using TR-FRET microscopy
Chemoselective boronic ester synthesis via controlled speciation

Control of boronic acid solution speciation is presented as a new strategy for the chemoselective synthesis of boronic esters. Manipulation of the solution equilibria within a cross-coupling milieu enables the formal homologation of aryl and alkenyl boronic acid pinacol esters. The generation of a new, reactive boronic ester in the presence of an active Pd catalyst also facilitates streamlined iterative catalytic C-C bond formation and provides a method for the controlled oligomerization of sp2-hybridized boronic esters
Photocatalytic Hydrogen Production using Polymeric Carbon Nitride with a Hydrogenase and a Bioinspired Synthetic Ni Catalyst

Solar light driven H2 production in water is reported with a [NiFeSe]-hydrogenase (H2ase) and a bio-inspired synthetic nickel catalyst (NiP) in combination with a heptazine carbon nitride polymer, melon (CNx). The semi-biological and purely synthetic systems show catalytic activity during solar AM 1.5G irradiation with turnover numbers (TONs) of more than 50,000 mol H2 (mol H2ase)–1 and approximately 155 mol H2
(mol NiP)–1 in redox mediator-free aqueous solution at pH 6 and 4.5, respectively. Both systems maintained a reduced photoactivity under UV-free solar light irradiation (λ > 420 nm).This is the final version. It was first published in Angewandte Chemie International Edition at http://onlinelibrary.wiley.com/doi/10.1002/anie.201406811/abstract
Intrinsic surface-drying properties of bioadhesive proteins

Sessile marine mussels must "dry" underwater surfaces before adhering to them. Synthetic adhesives have yet to overcome this fundamental challenge. Previous studies of bioinspired adhesion have largely been performed under applied compressive forces, but such studies are poor predictors of the ability of an adhesive to spontaneously penetrate surface hydration layers. In a force-free approach to measuring molecular-level interaction through surface-water diffusivity, different mussel foot proteins were found to have different abilities to evict hydration layers from surfaces - a necessary step for adsorption and adhesion. It was anticipated that DOPA would mediate dehydration owing to its efficacy in bioinspired wet adhesion. Instead, hydrophobic side chains were found to be a critical component for protein-surface intimacy. This direct measurement of interfacial water dynamics during force-free adsorptive interactions at solid surfaces offers guidance for the engineering of wet adhesives and coatings. Home and dry underwater: Repulsive hydration forces hinder wet adhesion in the absence of applied external forces. The direct measurement of hydration-water dynamics by NMR relaxometry at 10 GHz revealed that the most hydrophobic mussel adhesive protein, and not the most enriched with 3,4-dihydroxyphenylalanine, effectively dries the surface and overcomes repulsive hydration forces to adsorb spontaneously to surfaces in preparation for adhesion.National Science Foundation (NSF) through the MRSEC Program (DMR-1121053); MRSEC Program of the NSF (DMR-1121053); NIH Innovator Award; US National Institutes of Health (R01 DE018468); Human Frontiers of Science Progra
Enhancing fullerene-based solar cell lifetimes by addition of a fullerene dumbbell

Cost-effective, solution-processable organic photovoltaics (OPV) present an interesting alternative to inorganic silicon-based solar cells. However, one of the major remaining challenges of OPV devices is their lack of long-term operational stability, especially at elevated temperatures. The synthesis of a fullerene dumbbell and its use as an additive in the active layer of a PCDTBT:PCBM-based OPV device is reported. The addition of only 20 % of this novel fullerene not only leads to improved device efficiencies, but more importantly also to a dramatic increase in morphological stability under simulated operating conditions. Dynamic secondary ion mass spectrometry (DSIMS) and TEM are used, amongst other techniques, to elucidate the origins of the improved morphological stability.EPSRC (EP/F056710/1; EP/I019278/1; EP/G037515)NS
Bimetallic cyclometalated iridium(III) diastereomers with non-innocent bridging ligands for high-efficiency phosphorescent OLEDs.

Two phosphorescent dinuclear iridium(III) diastereomers (ΛΔ/ΔΛ) and (ΛΛ/ΔΔ) are readily separated by making use of their different solubilities in hot hexane. The bridging diarylhydrazide ligand plays an important role in the electrochemistry and photophysics of the complexes. Organic light-emitting devices (OLEDs) that use these complexes as the green-emissive dopants in solution-processable single-active-layer architectures feature electroluminescence efficiencies that are remarkably high for dinuclear metal complexes, achieving maximum values of 37 cd A−1, 14 lm W−1, and 11 % external quantum efficiency
Preparation of stereoregular isotactic poly(mandelic acid) through organocatalytic ring-opening polymerization of a cyclic O-carboxyanhydride

Poly(mandelic acid) (PMA) is an aryl analogue of poly(lactic acid) (PLA) and a biodegradable analogue of polystyrene. The preparation of stereoregular PMA was realized using a pyridine/mandelic acid adduct (Py⋅MA) as an organocatalyst for the ring-opening polymerization (ROP) of the cyclic O-carboxyanhydride (manOCA). Polymers with a narrow polydispersity index and excellent molecular-weight control were prepared at ambient temperature. These highly isotactic chiral polymers exhibit an enhancement of the glass-transition temperature (Tg ) of 15 °C compared to the racemic polymer, suggesting potential future application as high-performance commodity and biomedical materials
Zeolites with continuously tuneable porosity

Czech Science Foundation. Grant Number: P106/12/G015Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneable surface area and micropore volume over a wide range can be prepared. This means that a particular surface area or micropore volume can be precisely tuned. The range of porosity we can target covers the whole range of useful zeolite porosity: from small pores consisting of 8-rings all the way to extra-large pores consisting of 14-rings.Publisher PDFPeer reviewe
Coexistence of 3d-ferromagnetism and superconductivity in
  [(Li(1-x)Fex)OH](Fe(1-y)Liy)Se

Superconducting [(Li(1-x)Fex)OH](Fe(1-y)Liy)Se (x ~ 0.2, y ~ 0.08) was
synthesized by hydrothermal methods and structurally characterized by single
crystal X-ray diffraction. The crystal structure contains anti-PbO type
(Fe(1-y)Liy)Se layers separated by layers of (Li(1-x)Fex)OH. Electrical
resistivity and magnetic susceptibility measurements reveal superconductivity
at 43 K. An anomaly in the diamagnetic shielding indicates ferromagnetic
ordering near 10 K while superconductivity is retained. The ferromagnetism
emerges from the iron atoms in the (Li(1-x)Fex)OH layer. Isothermal
magnetization measurements confirm the superposition of ferromagnetic with
superconducting hysteresis. The internal ferromagnetic field is larger than the
lower, but smaller than the upper critical field of the superconductor, which
gives evidence for a spontaneous vortex phase where both orders coexist.
57Fe-M\"ossbauer spectra, 7Li-NMR spectra, and muSR experiments consistently
support this rare situation, especially in a bulk material where magnetism
emerges from a 3d-element.Comment: 13 pages, 7 Figure
Emulsion ripening through molecular exchange at droplet contacts

Two coarsening mechanisms of emulsions are well established: droplet coalescence (fusion of two droplets) and Ostwald ripening (molecular exchange through the continuous phase). Here a third mechanism is identified, contact ripening, which operates through molecular exchange upon droplets collisions. A contrast manipulated small‐angle neutron scattering experiment was performed to isolate contact ripening from coalescence and Ostwald ripening. A kinetic study was conducted, using dynamic light scattering and monodisperse nanoemulsions, to obtain the exchange key parameters. Decreasing the concentration or adding ionic repulsions between droplets hinders contact ripening by decreasing the collision frequency. Using long surfactant chains and well‐hydrated heads inhibits contact ripening by hindering fluctuations in the film. Contact ripening can be controlled by these parameters, which is essential for both emulsion formulation and delivery of hydrophobic ingredients
An efficient method for the in vitro production of Azol(in)e-based cyclic peptides

This paper was funded by: Funded Access, Leverhulme Trust. Grant Number: RPG-2012-504, TSB. Grant Number: 131181, ERC. Grant Number: 339367, and BBSRC. Grant Number: BB/K015508/1Heterocycle-containing cyclic peptides are promising scaffolds for the pharmaceutical industry but their chemical synthesis is very challenging. A new universal method has been devised to prepare these compounds by using a set of engineered marine-derived enzymes and substrates obtained from a family of ribosomally produced and post-translationally modified peptides called the cyanobactins. The substrate precursor peptide is engineered to have a non-native protease cleavage site that can be rapidly cleaved. The other enzymes used are heterocyclases that convert Cys or Cys/Ser/Thr into their corresponding azolines. A macrocycle is formed using a macrocyclase enzyme, followed by oxidation of the azolines to azoles with a specific oxidase. The work is exemplified by the production of 17 macrocycles containing 6-9 residues representing 11 out of the 20 canonical amino acids.Publisher PDFPeer reviewe
Dual Binding of an Antibody and a Small Molecule Increases the Stability of TERRA G-Quadruplex

In investigating the binding interactions between the human telomeric RNA (TERRA) G-quadruplex (GQ) and its ligands, it was found that the small molecule carboxypyridostatin (cPDS) and the GQ-selective antibody BG4 simultaneously bind the TERRA GQ. We previously showed that the overall binding affinity of BG4 for RNA GQs is not significantly affected in the presence of cPDS. However, single-molecule mechanical unfolding experiments revealed a population (48 %) with substantially increased mechanical and thermodynamic stability. Force-jump kinetic investigations suggested competitive binding of cPDS and BG4 to the TERRA GQ. Following this, the two bound ligands slowly rearrange, thereby leading to the minor population with increased stability. Given the relevance of G-quadruplexes in the regulation of biological processes, we anticipate that the unprecedented conformational rearrangement observed in the TERRA-GQ–ligand complex may inspire new strategies for the selective stabilization of G-quadruplexes in cells.H.M. acknowledges support from NSF CHE-1026532. The Balasubramanian
lab is supported by programme funding from Cancer
Research UK.This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/anie.201408113/abstract;jsessionid=BB18FC03F2AF0C3EB95EC57CCBDB3DB9.f01t01
Ionizable Amphiphilic Dendrimer-Based Nanomaterials with Alkyl-Chain-Substituted Amines for Tunable siRNA Delivery to the Liver Endothelium In Vivo

A library of dendrimers was synthesized and optimized for targeted small interfering RNA (siRNA) delivery to different cell subpopulations within the liver. Using a combinatorial approach, a library of these nanoparticle-forming materials was produced wherein the free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers were substituted with alkyl chains of increasing length, and evaluated for their ability to deliver siRNA to liver cell subpopulations. Interestingly, two lead delivery materials could be formulated in a manner to alter their tissue tropism within the liver—with formulations from the same material capable of preferentially delivering siRNA to 1) endothelial cells, 2) endothelial cells and hepatocytes, or 3) endothelial cells, hepatocytes, and tumor cells in vivo. The ability to broaden or narrow the cellular destination of siRNA within the liver may provide a useful tool to address a range of liver diseases.National Institutes of Health (U.S.)  Centers of Cancer and Nanotechnology Excellence (Grant U54 CA151884)Armed Forces Institute of Regenerative Medicine (Grant W81XWH-08-2-0034)Alnylam Pharmaceuticals (Firm
In situ synchrotron IR microspectroscopy of CO2 adsorption on single crystals of the functionalised MOF, Sc2(BDC-NH2)3

The authors thank the EPSRC (Grant Number: EP/J02077X/1), CONACYT Mexico, and the University of Edinburgh for funding this research.Synchrotron radiation (SR) IR microspectroscopy has enabled determination of the thermodynamics, kinetics, and molecular orientation of CO2 adsorbed in single microcrystals of a functionalized metal–organic framework (MOF) under conditions relevant to carbon capture from flue gases. Single crystals of the small-pore MOF, Sc2(BDC-NH2)3, (BDC-NH2=2-amino-1,4-benzenedicarboxylate), with well-defined crystal form have been investigated during CO2 uptake at partial pressures of 0.025-0.2 bar at 298–373 K. The enthalpy and diffusivity of adsorption determined from individual single crystals are consistent with values obtained from measurements on bulk samples. The brilliant SR IR source permits rapid collection of polarized spectra. Strong variations in absorbance of the symmetric stretch of the NH2 groups of the MOF and the asymmetric stretch of the adsorbed CO2 at different orientations of the crystals relative to the polarized IR light show that CO2 molecules align along channels in the MOF.Publisher PDFPeer reviewe
Direct surface-enhanced Raman scattering analysis of DNA duplexes

The exploration of the genetic information carried by DNA has become a major scientific challenge. Routine DNA analysis, such as PCR, still suffers from important intrinsic limitations. Surface-enhanced Raman spectroscopy (SERS) has emerged as an outstanding opportunity for the development of DNA analysis, but its application to duplexes (dsDNA) has been largely hampered by reproducibility and/or sensitivity issues. A simple strategy is presented to perform ultrasensitive direct label-free analysis of unmodified dsDNA with the means of SERS by using positively charged silver colloids. Electrostatic adhesion of DNA promotes nanoparticle aggregation into stable clusters yielding intense and reproducible SERS spectra at nanogram level. As potential applications, we report the quantitative recognition of hybridization events as well as the first examples of SERS recognition of single base mismatches and base methylations (5-methylated cytosine and N6-methylated Adenine) in duplexes
Catalyst-Controlled Stereoselective Olefin Metathesis as a Principal Strategy in Multistep Synthesis Design: A Concise Route to (+)-Neopeltolide

Molybdenum-, tungsten-, and ruthenium-based complexes that control the stereochemical outcome of olefin metathesis reactions have been recently introduced. However, the complementary nature of these systems through their combined use in multistep complex molecule synthesis has not been illustrated. A concise diastereo- and enantioselective route that furnishes the anti-proliferative natural product neopeltolide is now disclosed. Catalytic transformations are employed to address every stereochemical issue. Among the featured processes are an enantioselective ring-opening/cross-metathesis promoted by a Mo monoaryloxide pyrrolide (MAP) complex and a macrocyclic ring-closing metathesis that affords a trisubstituted alkene and is catalyzed by a Mo bis(aryloxide) species. Furthermore, Z-selective cross-metathesis reactions, facilitated by Mo and Ru complexes, have been employed in the stereoselective synthesis of the acyclic dienyl moiety of the target molecule.National Institutes of Health (U.S.) (NIH grant GM-59426)National Institutes of Health (U.S.) (NIH grant GM-57212)AstraZeneca (Firm) (Graduate Fellowship)National Science Foundation (U.S.) (NSF award CHE-1362763
Spontaneous CO Release from RuII(CO)2–Protein Complexes in Aqueous Solution, Cells, and Mice

We demonstrate that RuII(CO)2–protein complexes, formed by the reaction of the hydrolytic decomposition products of [fac-RuCl(κ2-H2NCH2CO2)(CO)3] (CORM-3) with histidine residues exposed on the surface of proteins, spontaneously release CO in aqueous solution, cells, and mice. CO release was detected by mass spectrometry (MS) and confocal microscopy using a CO-responsive turn-on fluorescent probe. These findings support our hypothesis that plasma proteins act as CO carriers after in vivo administration of CORM-3. CO released from a synthetic bovine serum albumin (BSA)–RuII(CO)2 complex leads to downregulation of the cytokines interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α in cancer cells. Finally, administration of BSA–RuII(CO)2 in mice bearing a colon carcinoma tumor results in enhanced CO accumulation at the tumor. Our data suggest the use of RuII(CO)2–protein complexes as viable alternatives for the safe and spatially controlled delivery of therapeutic CO in vivo.We thank the FCT, the EU, and the EPSRC for funding. G.J.L.B. is
a Royal Society University Research Fellow.This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/anie.201409344/abstract
A Systems Approach towards an Intelligent and Self-Controlling Platform for Integrated Continuous Reaction Sequences

Performing reactions in flow can offer major advantages over
batch methods. However, laboratory flow chemistry processes are currently
often limited to single steps or short sequences due to the complexity
involved with operating a multi-step process. Using new modular
components for downstream processing, coupled with control technologies,
more advanced multi-step flow sequences can be realized. Here, we report
the application of these tools to the synthesis of 2-aminoadamantane-2-
carboxylic acid. A system comprising three chemistry steps and three
workup steps was developed, having sufficient autonomy and selfregulation
to be managed by a single operator.The authors gratefully acknowledge support from Ralph Raphael
Scholarship (RJI), Woolf Fisher Trust (DEF), UK Engineering
and Physical Sciences Research Council (ES and SVL) and
Pfizer Worldwide Research and Development (CB and JMH).This is thefinal version. It was first published by Wiley at http://onlinelibrary.wiley.com/doi/10.1002/anie.201409356/abstrac