pinecone/core-2020-05-10-deduplication huggingface dataset:
Triplet harvesting with a simple aromatic carbonyl.

The efficiency of organic light-emitting diodes crucially depends on triplet harvesters. These accept energy from triplet correlated electron hole pairs and convert it into light. Here, experimental evidence is given that simple aromatic carbonyls, such as thioxanthone, could serve this purpose. In these compounds, the emissive 1ππ* excitation may rapidly equilibrate with an upper triplet state (3nπ*). This equilibrium may persist for nanoseconds. Population of the 3nπ* state via energy transfer from an electron hole pair should result in fluorescence emission and thereby triplet harvesting. To demonstrate the effect, solutions of 1,4-dichlorobenzene (triplet sensitizer) and thioxanthone (harvester) were excited at 266 nm with a nanosecond laser. The emission decay reveals a 100 ns decay absent in the thioxanthone only sample. This matches predictions for an energy transfer limited by diffusion and gives clear evidence that thioxanthone can convert triplet excitations into light
Understanding brønsted-acid catalyzed monomolecular reactions of Alkanes in Zeolite Pores by combining insights from experiment and theory

Acidic zeolites are effective catalysts for the cracking of large hydrocarbon molecules into lower molecular weight products required for transportation fuels. However, the ways in which the zeolite structure affects the catalytic activity at BrOnsted protons are not fully understood. One way to characterize the influence of the zeolite structure on the catalysis is to study alkane cracking and dehydrogenation at very low conversion, conditions for which the kinetics are well defined. To understand the effects of zeolite structure on the measured rate coefficient (k(app)), it is necessary to identify the equilibrium constant for adsorption into the reactant state (Kads-H+) and the intrinsic rate coefficient of the reaction (k(int)) at reaction temperatures, since k(app) is proportional to the product of Kads-H+ and k(int). We show that Kads-H+ cannot be calculated from experimental adsorption data collected near ambient temperature, but can, however, be estimated accurately from configurational-bias Monte Carlo (CBMC) simulations. Using monomolecular cracking and dehydrogenation of C-3-C-6 alkanes as an example, we review recent efforts aimed at elucidating the influence of the acid site location and the zeolite framework structure on the observed values of k(app) and its components, Kads-H+ and k(int)
PMO-immobilized Au-I-NHC complexes : heterogeneous catalysts for sustainable processes

A stable periodic mesoporous organosilica (PMO) with accessible sulfonic acid functionalities is prepared via a one-pot-synthesis and is used as solid support for highly active catalysts, consisting of gold(I)-N-heterocyclic carbene (NHC) complexes. The gold complexes are successfully immobilized on the nanoporous hybrid material via a straightforward acid-base reaction with the corresponding [Au(OH)(NHC)] synthon. This catalyst design strategy results in a boomerang-type catalyst, allowing the active species to detach from the surface to perform the catalysis and then to recombine with the solid after all the starting material is consumed. This boomerang behavior is assessed in the hydration of alkynes. The tested catalysts were found to be active in the latter reaction, and after an acidic work-up, the IPr*-based gold catalyst can be recovered and then reused several times without any loss in efficiency
Influence of a confined methanol solvent on the reactivity of active sites in UiO-66

UiO-66, composed of Zr-oxide bricks and terephthalate linkers, is currently one of the most studied metal-organic frameworks due to its exceptional stability. Defects can be introduced in the structure, creating undercoordinated Zr atoms which are Lewis acid sites. Here, additional BrOnsted sites can be generated by coordinated protic species from the solvent. In this Article, a multilevel modeling approach was applied to unravel the effect of a confined methanol solvent on the active sites in UiO-66. First, active sites were explored with static periodic density functional theory calculations to investigate adsorption of water and methanol. Solvent was then introduced in the pores with grand canonical Monte Carlo simulations, followed by a series of molecular dynamics simulations at operating conditions. A hydrogen-bonded network of methanol molecules is formed, allowing the protons to shuttle between solvent methanol, adsorbed water, and the inorganic brick. Upon deprotonation of an active site, the methanol solvent aids the transfer of protons and stabilizes charged configurations via hydrogen bonding, which could be crucial in stabilizing reactive intermediates. The multilevel modeling approach adopted here sheds light on the important role of a confined solvent on the active sites in the UiO-66 material, introducing dynamic acidity in the system at finite temperatures by which protons may be easily shuttled from various positions at the active sites
Neurophysiology of skin thermal sensations

This paper was accepted for publication in the journal Comprehensive Physiology and the definitive published version is available at http://dx.doi.org/10.1002/cphy.c150040Undoubtedly, adjusting our thermoregulatory behavior represents the most effective mechanism to maintain thermal homeostasis and ensure survival in the diverse thermal environments that we face on this planet. Remarkably, our thermal behavior is entirely dependent on the ability to detect variations in our internal (i.e., body) and external environment, via sensing changes\ud
in skin temperature and wetness. In the past 30 years, we have seen a significant expansion of our understanding of the molecular, neuroanatomical, and neurophysiological mechanisms that allow humans to sense temperature and humidity. The discovery of temperature-activated ion\ud
channels which gate the generation of action potentials in thermosensitive neurons, along with the characterization of the spino-thalamo-cortical thermosensory pathway, and the development of neural models for the perception of skin wetness, are only some of the recent advances which have provided incredible insights on how biophysical changes in skin temperature and wetness\ud
are transduced into those neural signals which constitute the physiological substrate of skin thermal and wetness sensations. Understanding how afferent thermal inputs are integrated and how these contribute to behavioral and autonomic thermoregulatory responses under normal brain function is\ud
critical to determine how these mechanisms are disrupted in those neurological conditions, which see the concurrent presence of afferent thermosensory abnormalities and efferent thermoregulatory\ud
dysfunctions. Furthermore, advancing the knowledge on skin thermal and wetness sensations is crucial to support the development of neuroprosthetics. In light of the aforementioned text, this review will focus on the peripheral and central neurophysiological mechanisms underpinning skin thermal and wetness sensations in humans
Kinetic study of thermal 1,3-dipolar cycloaddition of azomethine ylides using differential scanning calorimetry as monitoring window

Kinetics of 1,3-dipolar cycloaddition involving azomethine ylides, generated from thermal [1,2]-prototropy of the corresponding imino ester, employing differential scanning calorimetry (DSC), is surveyed. Glycine and phenylalanine derived imino esters have different behavior. The first one prefers reacting with itself at 75 ºC, rather than with the dipolarophile. However, the α-substituted imino ester gives the cycloadduct at higher temperatures. The thermal dynamic analysis by 1H NMR of the neat reaction mixture of the glycine derivative reveals the presence of signals corresponding to the dipole in very small proportion. The non-isothermal and isothermal DSC curves of the cycloaddition of phenylalaninate and diisobutyl fumarate are obtained from freshly prepared samples. The application of known kinetic models and mathematical multiple non-linear regressions (NLR) allow to determine and to compare Ea, lnA, reaction orders, and reaction enthalpy. Finally a rate equation for each different temperature can be established for this particular thermal cycloaddition.This work has been supported by the Spanish Ministerio de Ciencia e Innovación (MICINN) (Consolider INGENIO 2010 CSD2007-00006, CTQ2010-20387, FEDER, Generalitat Valenciana (PROMETEO/2009/039), and by the University of Alicante
Bioorthogonal Chemical Handle for Tracking Multifunctional Nanoparticles

Nanoparticle technologies have tremendous potential in clinical medicine. To fully realize this potential, one must further understand how nanoparticles interact with biological systems. Typically, reporters that are conjugated to nanoparticles during synthesis are used to monitor the nanoparticles in biological systems. Unfortunately, conjugating reporters to nanoparticles complicates the synthesis and the reporter itself may alter the nanoparticle properties. To address these challenges, a copper‐catalyzed azide–alkyne cycloaddition strategy has been developed to functionalize nanoparticles with fluorescent reporters after they have been delivered to biological systems. Using polyamidoamine dendrimers as model nanoparticles, the utility of this strategy is shown in several biological systems including a cancer cell model, primary immune cells, and a murine model of inflammation. This reporter strategy simplifies the synthesis without sacrificing the ability to monitor the nanoparticle conjugates. It is expected that this bioorthogonal reporter strategy can be used to understand nanoparticle interactions in biological systems, which will facilitate the translation of these technologies to the clinics.     Getting a handle on it : An innovative strategy for tracking multifunctional nanoparticles in biological systems is presented that simplifies the syntheses and can be used to track the nanoparticles in vitro and in vivo. The strategy is based on in situ click chemistry ligation of fluorescent reporters to the nanoparticle scaffold through copper‐catalyzed azide–alkyne cycloaddition (see figure)
The Gelling Ability of Some Diimidazolium Salts: Effect of\ud
Isomeric Substitution of the Cation and Anion

The gelling ability of some geminal imidazolium salts was investigated\ud
both in organic solvents and in water solution. Organic\ud
salts differing either in the cation or anion structure\ud
were taken into account. In particular, the effects on the gelphase\ud
formation of isomeric substitution on the cation or\ud
anion as well as of the use of mono- or dianions were evaluated.\ud
As far as the cation structure is concerned, isomeric cations,\ud
such as 3,3’-di-n-octyl-1,1’-(1,4-phenylenedimethylene)diimidazolium\ud
and 3,3’-di-n-octyl-1,1’-(1,3-phenylenedimethylene)\ud
diimidazolium, were used. On the other hand, in addition\ud
to the bromide anion, isomeric dianions, such as the 1,5- and\ud
2,6-naphthalenedisulfonate anions, were also examined. After\ud
preliminary gelation tests, different factors affecting the obtained\ud
gel phases, such as the nature of the solvent, organogelator\ud
concentrations, and action of external stimuli, were analyzed.\ud
The gel-phase formation was also studied as a function\ud
of time, by using resonance light scattering measurements. Gel\ud
morphologies were analyzed by scanning electron microscopy.\ud
To further support the understanding of the different behavior\ud
shown by the isomeric cations, some representative ion pairs\ud
were analyzed by DFT-based investigations. The collected data\ud
underline the significant role played by isomeric substitution\ud
of both cation and anion structures in determining the gelling\ud
capability of the investigated salts, as well as the properties of\ud
the gel phases. Finally, DFT investigations were helpful in the\ud
identification of the structural features affecting the self-assembly
Cooperative effects in the detection of a nitroaliphatic liquid explosive and na explosive taggant in the vapor phase by calix[4]arene-based carbazole-containing conjugated polymers

Two fluorescent molecular receptor based conjugated polymers were used in the detection of a nitroaliphatic liquid explosive (nitromethane) and an explosive taggant (2,3-dimethyl-2,3-dinitrobutane) in the vapor phase. Results have shown that thin films of both polymers display remarkably high sensitivity and selectivity toward these analytes. Very fast, reproducible, and reversible responses were found. The unique behavior of these supramolecular host systems is ascribed to cooperativity effects developed between the calix[4] arene hosts and the phenylene ethynylene-carbazolylene main chains. The calix[4]-arene hosts create a plethora of host-guest binding sites along the polymer backbone, either in their bowl-shaped cavities or between the outer walls of the cavity, to direct guests to the area of the transduction centers (main chain) at which favorable photoinduced electron transfer to the guest molecules occurs and leads to the observed fluorescence quenching. The high tridimensional porous nature of the polymers imparted by the bis-calixarene moieties concomitantly allows fast diffusion of guest molecules into the polymer thin films
Fabrication of metal-nanoparticle-modified semiconducting copper--and silver--TCNQ materials as substrates for the reduction of chromium (VI) using thiosulfate ions at ambient temperature

The formation of readily recoverable and reusable organic semiconducting Cu- and AgTCNQ (TCNQ=7,7,8,8-tetracyanoquinodimethane) microstructures decorated with Pt and Pd metallic nanoparticles is described for the effective reduction of CrVI ions in aqueous solution at room temperature using both formic acid and an environmentally friendly thiosulfate reductant. The M-TCNQ (M=metal) materials were formed by electrocrystallisation onto a glassy carbon surface followed by galvanic replacement in the presence of H2PtCl6 or PdCl2 to form the composite material. It was found that loading of the surface with nanoparticles could easily be controlled by changing the metal salt concentration. Significantly, the M-TCNQ substrates facilitated the formation of well-isolated metal nanoparticles on their surfaces under appropriate galvanic replacement conditions. The semiconductor–metal nanoparticle combination was also found to be critical to the catalyst performance, wherein the best-performing material was CuTCNQ modified by well-isolated Pt nanoparticles with both formic acid and thiosulfate ions as the reductant
The development of Zn-Ce hybrid redox flow batteries for energy storage and their continuing challenges

The Zn-Ce flow battery is a recently introduced hybrid redox flow battery (RFB) but has been extensively studied in the laboratory and at the industrial pilot-scale since its introduction in 2005. The cell has the highest open-circuit cell potentials amongst aqueous RFBs, which can exceed 2.4 V at full charge. While original patents were filed in 2004 and 2005, the history of the half-cell reactions stretches back many decades, the Ce(IV)/Ce(III) redox couple being well studied in sulphuric acid as a redox mediator in organic electrosynthesis or in nitric acid for specialist cleaning in the chemical and nuclear industries while zinc deposition and stripping in acid media are well known in hydrometallurgy and electroplating of metals as well as in other batteries using zinc negative electrodes. Methanesulfonic acid electrolytes were introduced in surface finishing several decades ago but their use in flow batteries is only 20 years old. This review considers the thermodynamics and kinetics of the electrode reactions (desired and secondary) in each half-cell, operational variables, materials for cell components, cell design and performance of the zinc-cerium flow battery. Continuing challenges are highlighted and critical research needs for the science and technological development are considered
Mechanistic details of the membrane perforation and passive translocation of TAT peptides

The trans-activator of transcription (TAT) peptide is regarded as the “gold standard” for cell-penetrating peptides, capable of traversing a mammalian membrane passively into the cytosolic space. This characteristic has been exploited through conjugation of TAT for applications such as drug delivery. However, the process by which TAT achieves membrane penetration remains ambiguous and unresolved. Mechanistic details of TAT peptide action are revealed herein by using three complementary methods: quartz crystal microbalance with dissipation (QCM-D), scanning electrochemical microscopy (SECM) and atomic force microscopy (AFM). When combined, these three scales of measurement define that the membrane uptake of the TAT peptide is by trans-membrane insertion using a “worm-hole” pore that leads to ion permeability across the membrane layer. AFM data provided nanometre-scale visualisation of TAT punctuation using a mammalian-mimetic membrane bilayer. The TAT peptide does not show the same specificity towards a bacterial mimetic membrane and QCM-D and SECM showed that the TAT peptide demonstrates a disruptive action towards these membranes. This investigation supports the energy-independent uptake of the cationic TAT peptide and provides empirical data that clarify the mechanism by which the TAT peptide achieves its membrane activity. The novel use of these three biophysical techniques provides valuable insight into the mechanism for TAT peptide translocation, which is essential for improvements in the cellular delivery of TAT-conjugated cargoes including therapeutic agents required to target specific intracellular locations
Electropolymerisation of catalytically active PEDOT from an ionic liquid on a flexible carbon cloth using a sandwich cell configuration

We report the electropolymerization of poly(3,4-ethylenedioxythiopene) (PEDOT) from an ionic liquid, butyl-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (C4mpyrTFSI) onto flexible carbon cloth electrodes. A continuous, homogeneous and well adhered coating of the individual cloth fibres is achieved by employing a sandwich cell arrangement where the carbon cloth which is soaked with electrolyte is placed between two indium tin oxide electrodes isolated from each other by a battery separator. The resultant PEDOT modified carbon cloth electrode demonstrates excellent activity for the oxygen reduction reaction which is due to the doping level, conductivity and morphology of the PEDOT layer and is also tolerant to the presence of methanol in the electrolyte. This simple approach therefore offers a route to fabricate flexible polymer electrodes that could be used in various electronic applications
Controlling Localization and Excretion of Nanoparticles by Click Modification of the Surface Chemical Structures inside Living Cells

Surface modification of silica nanoparticles (SiNPs) inside living cells was conducted by using the copper-free bioorthogonal click reaction to evaluate the effects of surface chemical structures on dynamic behavior and excretion of SiNPs. The results demonstrated the spatial translocation of intracellular SiNPs to the plasma membrane upon surface modification in situ with phospholipids. Moreover, the extent and kinetics of excretion of the SiNPs from inside the cell were enhanced by modification
Superhydrophobic fabrics for oil-water separation based on the metal organic charge transfer complex CuTCNAQ

This work reports on the fabrication of a superhydrophobic nylon textile based on the organic charge transfer complex CuTCNAQ (TCNAQ = 11,11,12,12-tetracyanoanthraquinodimethane). The nylon fabric that is metallized with copper undergoes a spontaneous chemical reaction with TCNAQ dissolved in acetonitrile to form nanorods of CuTCNAQ that are intertwined over the entire surface of the fabric. This creates the necessary micro and nanoscale roughness that is required for the Cassie-Baxter state thereby achieving a superhydrophobic/superoleophilic surface without the need for a fluorinated surface. The material is characterised with SEM, FT-IR and XPS spectroscopy and investigated for its ability to separate oil and water in two modes, namely under gravity and as an absorbent. It is found that the fabric can separate dichloromethane, olive oil and crude oil from water and in fact reduce the water content of the oil during the separation process. The fabric is reusable and tolerant to conditions such as seawater, hydrochloric acid and extensive time periods on the shelf. Given that CuTCNAQ is a copper based semiconductor may also open up the possibility of other applications in areas such as photocatalysis and antibacterial applications
Synthesis and Photoinduced Electron-Transfer Reactions in a La2@Ih-C80–Phenoxazine Conjugate

A newly designed electron donor–acceptor conjugate consisting of an endohedral dimetallofullerene (La2@Ih‐C80) and phenoxazine (POZ) was successfully synthesized under Prato conditions. Our results document that the 1,3‐dipolar cycloaddition took place across the [5,6] junction to afford exclusively the corresponding [5,6] cycloadduct. The structure of the conjugate was characterized by means of NMR spectroscopy, absorption spectroscopy, and electrochemical studies. Computational calculations suggest that the electron density of the highest occupied molecular orbital (HOMO) is distributed on the POZ moiety, whereas that of the lowest unoccupied molecular orbital (LUMO) is located at the endohedral La atoms, leading to efficient separation of the HOMO and LUMO in the conjugate. Time‐resolved absorption spectroscopic investigations and spectroelectrochemical measurements corroborate the formation of the energetically low‐lying (La2@Ih‐C80).−–(POZ).+ radical‐ion‐pair state by means of ultrafast through‐space electron transfer
Anticancer RuII and RhIII piano-stool complexes that are histone deacetylase inhibitors.

The first examples of RuII and RhIII piano-stool complex histone deacetylase (HDAC) inhibitors are presented. The novel complexes have antiproliferative activity against H460 non-small-cell lung carcinoma cells that is comparable to the clinically used HDAC inhibitor suberoylanilide hydroxamic acid (SAHA). Strong evidence for HDAC inhibition as a primary mechanism of action is provided. The complexes reported here represent an important step towards the design of highly active and selective HDAC inhibitors
Probing the Surface of a Laccase for Clues towards the Design of Chemo-Enzymatic Catalysts

Systems featuring a multi-copper oxidase associated with transition-metal complexes can be used to perform oxidation reactions in mild conditions. Here, a strategy is presented for achieving a controlled orientation of a ruthenium–polypyridyl graft at the surface of a fungal laccase. Laccase variants are engineered with unique surface-accessible lysine residues. Distinct ruthenium–polypyridyl-modified laccases are obtained by the reductive alkylation of lysine residues precisely located relative to the T1 copper centre of the enzyme. In none of these hybrids does the presence of the graft compromise the catalytic efficiency of the enzyme on the substrate 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). Furthermore, the efficiency of the hybrids in olefin oxidation coupled to the light-driven reduction of O2 is highly dependent on the location of the graft at the enzyme surface. Simulated RuII–CuII electron coupling values and distances fit well the observed reactivity and could be used to guide future hybrid designs.L.S. was the recipient of a MinistHre de l’Education Nationale fellowship.\ud
This study was supported by grants from the Agence Nationale de la Recherche (ANR-09-BLANC-0176 and ANR-15-CE07-0021-01) and from the Ministerio de EconomÍa, Industria y\ud
Competitividad (CTQ2016-79138-R). We thank Elise Courvoisier-Dezord from the Plateforme AVB (AMU): Analyse et Valorisation\ud
de la Biodiversit8 and Yolande Charmasson for help in the production of the recombinant enzymes, as well as Pascal Mansuelle\ud
and R8gine Lebrun from the Plateforme Prot8omique (CNRSAMU) for help in acquiring mass spectrometry data.Peer ReviewedPostprint (published version