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The importance of systematic and efficient recycling of all forms of plastic is no longer a matter for debate. Constituting the sixth most produced polymer family worldwide, polyurethanes, which are used in a broad variety of applications (buildings, electronics, adhesives, sealants, etc.), are particularly important to recycle. In this study, polyurethanes are selectively recycled to obtain high value-added molecules. It is demonstrated that depolymerization reactions performed with secondary amines selectively cleave the C–O bond of the urethane group, while primary amines unselectively break C–O and C–N bonds. The selective cleavage of C–O bonds, catalyzed by an acid:base mixture, led to the initial polyol and a functional diurea in several hours to a few minutes for both model polyurethanes and commercial polyurethane foams. Different secondary amines were employed as nucleophiles to synthesize a small library of diureas obtained in good to excellent yields. This study not only targets the recovery of the initial polyol but also aims to form new diureas which are useful building blocks for the polymerization of innovative materials. C.J. acknowledges the financial support from el Ministerio de ciencia e innovación from the Juan de la Cierva Program (FJC2020045872-I). The funding from the European Union’s Horizon 2020 framework programme under the Marie Skłodowska Curie agreement No. 101028975 and Ministerio de ciencia e innovación under PDC2021-121461-I00 project are acknowledged.

The NEXT collaboration: et al., The Neutrino Experiment with a Xenon TPC (NEXT) searches for the neutrinoless double-beta (0νββ) decay of 136Xe using high-pressure xenon gas TPCs with electroluminescent amplification. A scaled-up version of this technology with about 1 tonne of enriched xenon could reach in less than 5 years of operation a sensitivity to the half-life of 0νββ decay better than 1027 years, improving the current limits by at least one order of magnitude. This prediction is based on a well-understood background model dominated by radiogenic sources. The detector concept presented here represents a first step on a compelling path towards sensitivity to the parameter space defined by the inverted ordering of neutrino masses, and beyond., The NEXT Collaboration acknowledges support from the following agencies and institutions: the European Research Council (ERC) under the Advanced Grant 339787-NEXT; the European Union’s Framework Programme for Research and Innovation Horizon 2020 (2014–2020) under the Grant Agreements No. 674896, 690575 and 740055; the Ministerio de Economía y Competitividad and the Ministerio de Ciencia, Innovación y Universidades of Spain under grants FIS2014-53371-C04, RTI2018-095979, the Severo Ochoa Program grants SEV-2014-0398 and CEX2018-000867-S, and the María de Maeztu Program MDM2016-0692; the Generalitat Valenciana of Spain under grants PROMETEO/2016/120 and SEJI/2017/011; the Portuguese FCT under project PTDC/FIS-NUC/2525/2014 and under projects UID/FIS/04559/2020 to fund the activities of LIBPhys-UC; the Pazy Foundation (Israel) under grants 877040 and 877041; the US Department of Energy under contracts number DE-AC02-06CH11357 (Argonne National Laboratory), DE-AC02-07CH11359 (Fermi National Accelerator Laboratory), DE-FG02-13ER42020 (Texas A&M) and DE-SC0019223 / DE-SC0019054 (University of Texas at Arlington); and the University of Texas at Arlington. DGD acknowledges support from the Ramón y Cajal program (Spain) under contract number RYC-2015-18820. JM-A acknowledges support from Fundación Bancaria la Caixa (ID 100010434), grant code LCF/BQ/PI19/11690012, and from the Plan GenT program of the Generalitat Valenciana, grant code CIDEGENT/2019/049.

Observation of the neutrinoless double β decay is the only practical way to establish that neutrinos are their own antiparticles. Because of the small masses of neutrinos, the lifetime of neutrinoless double β decay is expected to be at least ten orders of magnitude greater than the typical lifetimes of natural radioactive chains, which can mimic the experimental signature of neutrinoless double β decay. The most robust identification of neutrinoless double β decay requires the definition of a signature signal—such as the observation of the daughter atom in the decay—that cannot be generated by radioactive backgrounds, as well as excellent energy resolution. In particular, the neutrinoless double β decay of Xe could be established by detecting the daughter atom, Ba, in its doubly ionized state. Here we demonstrate an important step towards a ‘barium-tagging’ experiment, which identifies double β decay through the detection of a single Ba ion. We propose a fluorescent bicolour indicator as the core of a sensor that can detect single Ba ions in a high-pressure xenon gas detector. In a sensor made of a monolayer of such indicators, the Ba dication would be captured by one of the molecules and generate a Ba-coordinated species with distinct photophysical properties. The presence of such a single Ba-coordinated indicator would be revealed by its response to repeated interrogation with a laser system, enabling the development of a sensor able to detect single Ba ions in high-pressure xenon gas detectors for barium-tagging experiments., We also acknowledge support from the following agencies and institutions: the European Research Council (ERC) under Advanced Grant 339787-NEXT; the Ministry of Science and Innovation of Spain and FEDER under grants FIS2014-53371-C04, FIS2016-76163-R, MAT2016-78293-C6-5-R, MINECO/FEDER CT2016-80955-P, CTQ2016-80375-P and CTQ2014-51912-REDC; Interred PCTEFA V-A Spain/France/Andorra Program (EFA 194/16/TNSI); the Basque Government (GV/EJ) under grants IT-1346-19 and IT-1180-19; andAgencia de Ciencia y Tecnología de la Región de Murcia (19897/GERM/15). The authors also thank the SGI/IZO-SGIker UPV/EHU, Fundación Séneca and DIPC for computational and analytical resources.

Parallel Flash Talk at the "XIX International Workshop on Neutrino Telescopes" on line - 18-26 February, 2021, on behalf of NEXT, {"references":["10.1038/s41586-020-2431-5"]}

The NEXT collaboration: et al., Next-generation neutrinoless double beta decay experiments aim for half-life sensitivities of ∼ 1027 yr, requiring suppressing backgrounds to < 1 count/tonne/yr. For this, any extra background rejection handle, beyond excellent energy resolution and the use of extremely radiopure materials, is of utmost importance. The NEXT experiment exploits differences in the spatial ionization patterns of double beta decay and single-electron events to discriminate signal from background. While the former display two Bragg peak dense ionization regions at the opposite ends of the track, the latter typically have only one such feature. Thus, comparing the energies at the track extremes provides an additional rejection tool. The unique combination of the topology-based background discrimination and excellent energy resolution (1% FWHM at the Q-value of the decay) is the distinguishing feature of NEXT. Previous studies demonstrated a topological background rejection factor of ∼ 5 when reconstructing electron-positron pairs in the 208Tl 1.6 MeV double escape peak (with Compton events as background), recorded in the NEXT-White demonstrator at the Laboratorio Subterráneo de Canfranc, with 72% signal efficiency. This was recently improved through the use of a deep convolutional neural network to yield a background rejection factor of ∼ 10 with 65% signal efficiency. Here, we present a new reconstruction method, based on the Richardson-Lucy deconvolution algorithm, which allows reversing the blurring induced by electron diffusion and electroluminescence light production in the NEXT TPC. The new method yields highly refined 3D images of reconstructed events, and, as a result, significantly improves the topological background discrimination. When applied to real-data 1.6 MeV e−e+ pairs, it leads to a background rejection factor of 27 at 57% signal efficiency.

Molecular entities whose fluorescence spectra are different when they bind metal cations are termed bicolour fluorescent molecular sensors. The basic design criteria of this kind of compound are presented and the different fluorescent responses are discussed in terms of their chemical behaviour and electronic features. These latter elements include intramolecular charge transfer (ICT), formation of intramolecular and intermolecular excimer/exciplex complexes and Förster resonance energy transfer (FRET). Changes in the electronic properties of the fluorophore based on the decoupling between its constitutive units upon metal binding are also discussed. The possibility of generating fluorescent bicolour indicators that can capture metal cations in the gas phase and at solid–gas interfaces is also discussed., In this perspective the main design criteria of fluorescent bicolour sensors for metallic cations are presented, as well as selected examples illustrating the high efficiency and versatility of this technique.

The aim of the present study was to analyse the neuroendocrine stress response, psychological anxiety response, and perceived match importance (PMI) between expert and non-expert control gamers in an official competitive context. We analyzed, in 25 expert esports players and 20 control participants, modifications in their somatic anxiety, cognitive anxiety, self-confidence, PMI, and cortisol in a League of Legends competition. We found how expert esports players presented higher cortisol concentrations (Z = 155.5; p = 0.03; Cohen’s d = −0.66), cognitive anxiety (Z = 99.5; p = 0.001), and PMI (Z = 50.5; p < 0.001) before the competition than non-experts participants. We found a greater statistical weight in the cognitive variables than in the physiological ones. The results obtained suggest that real competitive context and player’s expertise were factors associated with an anticipatory stress response. The PMI proved to be a differentiating variable between both groups, highlighting the necessity to include subjective variables that contrast objective measurements.

Different surface treatments including mercerization, stearic acid and growth of zinc oxide nanorods as well as their combinations were exploited to address their effects on the properties of green composites based on polylactic acid (PLA) and flax fabrics. The resulting fabrics were morphologically (SEM), crystallographically (XRD) and thermally (TGA) characterized, showing no significant changes with respect to the untreated samples. In contrast, tensile and flexural properties of composites produced by compression moulding were significantly influenced. A combination of mercerization and environmentally friendly stearic acid treatment turned the character of the flax fabric from hydrophilic to hydrophobic, and led to improved bending and tensile strengths by 20% and 12%, respectively, compared to untreated composites. The presence of ZnO nanorods promoted an increase in flexural and tensile stiffness by 58% and 31%, respectively, but at the expense of strength, with reductions ascribed to the degradation of polylactic acid under high-temperature conditions favoured by ZnO, as confirmed by a reduction in the initial thermal degradation temperature up to 26%. These latter composites can be suggested in those applications where a suitable combination of flexural properties and a shorter persistence in the environment is desired.

International audience; In a first instance, the effect of the microwave irradiation on the 1,3-Dioxa-[3,3]-sigmatropic rearrangement of aryl allylic carbamates was investigated. Under these new conditions, the reaction acceleration was clearly highlighted compared to conventional heating conditions. Depending on the electronic nature of substituents on the aromatic group, this type of rearrangement can be faster with similar or improved yields. Due to this experimental improvement, the diversity of aryl allylic carbamates able to undergo this rearrangement in a reasonable reaction time (30 min.) and with acceptable to high yields was greatly extended. Finally, an original synthetic way involving this microwave-assisted process to access new six-membered heterocyclic structures such as (E)-5-arylidene-1,3-oxazinane-2,4-diones was developed from Morita-Baylis-Hillman (MBH) adducts showing the interest of this molecular rearrangement approach. DFT and Fragment Distortion studies showed in general polar transition structures and connected high deformation and interaction energies with lower activation barriers.

The next generation of neutrinoless double beta decay searches aims to reach sensitivities in the half-life of the process up to $10^{28}$ years. This will require tonne scale detectors with almost no background in their region of interest, which represents a large improvement with respect to current technologies. One of the most interesting solutions is the possibility of tagging the daughter ion produced in the decay. The NEXT collaboration is currently involved in a strong R&D program based on fluorescent molecules that show promising results towards a single ion identification in pressure gas. I will show the latest results based on the spectral shift of the emission fluorescence of this molecule after Ba$^{++}$ capture in dry media. The emission light is then detected by Two Photon Absorption microscopy, which allows autofocus. Additionally, I will detail how this technique can be integrated into a xenon gas detector. https://www.youtube.com/watch?v=0l5_KLsLNuY&feature=youtu.be

According to the Challenge Hypothesis, high levels of testosterone (T) are associated with status-seeking behaviors, especially in competitive situations. However, there have not been many studies about rivals&rsquo, social status and pre-competition neuroendocrine responses. The aim of this study was to analyze whether the participants in a chess tournament showed different pre-match testosterone and cortisol levels depending on differences in ELO (i.e., the International Chess Federation rating to rank the competitive potential and social status between players). The sample was six male participants (mean &plusmn, SD) aged 25.5 &plusmn, 8.4 years with experience in official tournaments of 16.33 &plusmn, 5.72 years and an average ELO rating of 2217.67 &plusmn, 112.67. Saliva samples were collected before each round for hormonal determination when participants competed against a rival with a different ELO rating. After five competition rounds per participant, higher rival pre-competition T concentrations were shown when playing against the best-rated participant, but there were no differences in cortisol (C). The multilevel model confirmed rises in rivals&rsquo, precompetitive T levels modulated by the difference in the opponent&acute, s ELO rating. No significant changes were observed in C. The results suggest that the rival&acute, s status can determine the opponent&acute, s anticipatory neuroendocrine responses to an official chess tournament.

This study aimed to analyze the modulating effect of competition seriousness and competition level in the testosterone and cortisol responses in professional soccer player. Ninety five (95) soccer players were included in this study (professional, n = 39, semiprofessional, n = 27, amateur, n = 29) before and after training, friendly game and official games. Repeated measures ANOVA showed higher testosterone levels (F(1,89) = 134, p &lt, 0.0001, &eta, 2p = 0.75) in professional soccer players, when compared with semiprofessional (p &lt, 0.0001) or amateur athletes (p &lt, 0.0001). After winning a competition game an increase in testosterone levels was observed in professionals (t = &minus, 3.456, p &lt, 0.001), semiprofessionals (t = &minus, 4.400, p &lt, 0.0001), and amateurs (t = &minus, 2.835, p &lt, 0.009). In contrast, this momentary hormonal fluctuation was not observed after winning a friendly game or during a regular training day. Additionally, statistical analysis indicated that cortisol levels were lower in professional (t = &minus, 0.001) and semiprofessional athletes (t = &minus, 0.0001) than in amateurs (t = &minus, 0.009). In soccer players a rise in testosterone was only observable when the team was faced with an actual challenge but did not support a different response between categories. Thus, the desire to achieve a goal (and keep the social status) may be one of the key reasons why testosterone levels rise promptly. Conversely, testosterone did not change after friendly games, which suggests these situations are not real goals and the players do not perceive an actual threat (in terms of dominance) more than the preparation for their next competitive game.

The presence of a secondary phase between the fibres and the matrix has proved to be a good approach for interphase tailoring for enhanced load transfer. In this regard, an optimization of the low-...

International audience; The ideal mechanical performance of a composite is controlled by the level of interfacial adhesion and to overcome the incompatibility issues between plant fibres and polymeric matrices, the surface of flax yarns has been modified by zinc oxide (ZnO) nanostructures. The ZnO nanorods were synthesized through a lowtemperature hydrothermal treatment, and several parameters have been analysed in order to obtain a uniform and homogeneous ZnO interphase, such as the number of the seeding cycles, the growth reaction times and the replacement of the growth solution. The results showed that it is possible to obtain highly oriented and well aligned ZnO nanostructures (by FE-SEM), with an hexagonal wurtzite structure (by XRD) and a high degree of coverage along the whole yarn (by TGA), reducing the number of the seed cycles, with rather long growth times (5 hours) and substituting the growth solution at least once during the synthesis. The experimental conditions preserved the breaking force of the yarns, while Single Fibre Fragmentation Tests (SFFT) highlighted a better interfacial adhesion of ZnO-modified flax yarns with epoxy matrix, which displayed a 29 % reduction in average debonding length relative to untreated yarns.

Four different strategies for mitigating the highly hydrophilic nature of flax fibers were investigated with a view to increase their compatibility with apolar polypropylene. The effects of two carbon nanostructures (graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs)), of a chemical modification with a fatty acid (stearic acid), and of maleated polypropylene on interfacial adhesion, mechanical properties (tensile and flexural), and thermal stability (TGA) were compared. The best performance was achieved by a synergistic combination of GNPs and maleated polypropylene, which resulted in an increase in tensile strength and modulus of 42.46% and 54.96%, respectively, compared to baseline composites. Stearation proved to be an effective strategy for increasing the compatibility with apolar matrices when performed in an ethanol solution with a 0.4 M concentration. The results demonstrate that an adequate selection of surface modification strategies leads to considerable enhancements in targeted properties.

Background and Aims Polycystic liver diseases (PLDs) are genetic disorders characterized by progressive development of symptomatic biliary cysts. Current surgical and pharmacological approaches are ineffective, and liver transplantation represents the only curative option. Ursodeoxycholic acid (UDCA) and histone deacetylase 6 inhibitors (HDAC6is) have arisen as promising therapeutic strategies, but with partial benefits. Approach and Results Here, we tested an approach based on the design, synthesis, and validation of a family of UDCA synthetic conjugates with selective HDAC6i capacity (UDCA-HDAC6i). Four UDCA-HDAC6i conjugates presented selective HDAC6i activity, UDCA-HDAC6i #1 being the most promising candidate. UDCA orientation within the UDCA-HDAC6i structure was determinant for HDAC6i activity and selectivity. Treatment of polycystic rats with UDCA-HDAC6i #1 reduced their hepatomegaly and cystogenesis, increased UDCA concentration, and inhibited HDAC6 activity in liver. In cystic cholangiocytes UDCA-HDAC6i #1 restored primary cilium length and exhibited potent antiproliferative activity. UDCA-HDAC6i #1 was actively transported into cells through BA and organic cation transporters. Conclusions These UDCA-HDAC6i conjugates open a therapeutic avenue for PLDs. Supported by the Spanish Carlos III Health Institute (ISCIII; J.M. Banales: FIS PI15/01132, PI18/01075 and Miguel Servet Program CON14/00129; M.J. Perugorria: PI14/00399, PI17/00022; J.J.G. Marin: FIS PI16/00598) cofinanced by "Fondo Europeo de Desarrollo Regional" (FEDER); CIBERehd (ISCIII): J.M. Banales, M.J. Perugorria, L. Bujanda, and J.J.G. Marin; Spanish Ministry of Economy and Competitiveness (M. J. Perugorria: Ramon y Cajal Program RYC-2015-17755); IKERBASQUE, Basque foundation for Science (M.J. Perugorria and J.M. Banales), Spain; "Junta de Castilla y Leon" (J.J.G. Marin: SA06P17); " Diputacion Foral Gipuzkoa" (J.M. Banales: DFG15/010, DFG16/004; M.J. Perugorria: DFG18/114, DFG19/081), BIOEF (Basque Foundation for Innovation and Health Research: EiTB Maratoia BIO15/CA/016/BD to J.M. Banales), Department of Health of the Basque Country (J.M. Banales: 2017111010; M.J. Perugorria: 2019111024), and Euskadi RIS3 (J.M. Banales: 2016222001, 2017222014, and 2018222029; 2019222054); La Caixa Scientific Foundation (J.M. Banales: HR17-00601); "Fundacion Cientifica de la Asociacion Espanola Contra el Cancer" (AECC Scientific Foundation, to J.M. Banales and J.J.G. Marin); and "Centro Internacional sobre el Envejecimiento", Spain (J.J.G. Marin: OLD-HEPAMARKER, 0348-CIE-6-E). F.J. Caballero-Camino was funded by the Spanish Ministry of Science and Innovation (BES-2014-069148), A. Santos-Laso by the Basque Government (PRE_2018_2_0195), and Pui Y. Lee-Law by the European Association for the Study of the Liver (EASL; Sheila Sherlock Award). The Spanish Ministry of Science and Innovation supported F. P. Cossio: (CTQ2016-80375-P and CTQ2014-51912-REDC) as well as the Basque Government (F.P. Cossio: IT-324-07). I. Rivilla had a postdoctoral contract from the Donostia International Physics Center.

Designed repeat proteins catalyze the 1,3-dipolar reaction between an imine and a π-deficient dipolarophile in THF solution to form unnatural nitroproline esters, a reaction that no enzyme can catalyze. NMR studies and mutation experiments show that both acidic and basic residues can catalyze the reaction. The diastereocontrol of the reaction depends on the flexibility of the protein and on the number and location of the active lysine and glutamate residues, which can participate independently or forming dyads that promote the formation of unusual diastereomeric cycloadducts. QM/MM calculations permit one to rationalize the origins of this

The aim of the present study was to analyse differences in the psychoneuroendocrine stress responses of high-level, young swimmers depending on whether an autocratic and democratic coaching style was applied. Modifications in cortisol and the motivational climate of 18 young swimmers (15.3 &plusmn, 1.86 years, 10 females and 8 males) were analysed before and after two training sessions with equivalent training loads but directed by two coaches applying different approaches, i.e., autocratic (A) and democratic (D). The basal testosterone levels of the coaches were also assessed. The basal testosterone concentration was higher in coach A than in coach D, the athletes perceived them as autocratic and democratic, respectively. Swimmers under coach A&rsquo, s instructions showed higher cortisol levels, suggesting higher cortisol production related to coaching style. Furthermore, differences in the motivational climate concerning ego (i.e., athletes comparing their ability with that of other athletes) were observed with coach A, whereas differences in motivational climate concerning the task (i.e., athletes comparing their ability with their own past performance) were observed with coach D. Cognitive variables showed negative perceptions affecting athletes&rsquo, training experience and performance when they were screamed at or insulted by coach A. There were no gender or age differences in cortisol production or motivational climate. In conclusion, this study suggests that an autocratic coaching style modulates cortisol release in both genders, affecting young elite swimmers&rsquo, motivational climate and training experience.

Chlorosulfate derivatives are interesting reagents that have been traditionally used to get other sulfur-containing compounds by formal nucleophilic substitution of the chlorine atom. This work describes a different mode of reactivity of alkyne-containing chlorosulfates to get sultones, the sulfur analogues of lactones. The complex skeletal rearrangement observed in this transformation is comparable to those intricate processes promoted or catalyzed by organometallic compounds. However, the reaction here described does not require any reagent or additive, being just a thermal process. Computational calculations support a mechanism based on a series of cascade reactions where almost every step is counterintuitive. Some of these steps include original processes related to classical reactions, thus adding complementary views to traditional organic chemistry.

A highly enantioselective catalytic method for the synthesis of quaternary α-trifluoromethyl derivatives of 3-oxo esters is described. The reaction uses lanthanum(III) triflate and chiral PyBOX-type C2 -symmetric ligands to generate intermediate LaIII complexes that incorporate an enolate moiety of the starting 3-oxo ester and the trifluoromethylation transfer reagent. The enantioselectivity of the reaction stems from the efficient blockage of one of the prochiral faces of the LaIII enolate by one unit of the C2 -symmetric ligand.

Although various chemistries have been introduced into polyurethanes in order to obtain self-healing abilities, implementing these materials in applications requiring high strength is challenging as strong materials imply a limited molecular motion, but without movement of polymer chains self-healing is not possible. Here, waterborne poly(urethane-urea)s (PU(U)s) based on aromatic disulfide compounds are developed which balance these contradictory requirements by presenting good mechanical properties at room temperature, while showing the mobility necessary for healing when moderately heated. The influence of hard monomers on the stability and mobility of the materials is investigated by scratch closure, cut healing and rheological measurements, so that the limits of the readily available aromatic disulfide compounds, bis(4-aminophenyl)- and bis(4-hydroxyphenyl)disulfide, can be determined. Subsequently, a modified aromatic disulfide compound, bis[4-(3'-hydroxypropoxy)phenyl]disulfide, with increased reactivity, solubility and flexibility is synthesized and incorporated into the PU backbone, so that materials with more attractive mechanical properties, reaching ultimate tensile strengths up to 23 MPa, and self-healing abilities at elevated temperatures could be obtained. The European Union’s Horizon 2020 research and innovation programme is accredited for the financial support through Project TRACKWAY-ITN 642514 under the Marie Sklodowska-Curie grant agreement. N.B. acknowledges the financial support obtained through the Post-Doctoral fellowship Juan de la Cierva - Incorporación (IJCI-2016-28442), from the Ministry of Economy and Competitiveness of Spain

International audience; An unexpected 1,3-dioxa-[3,3]-sigmatropic rearrangement during the treatment of aryl-and alkenyl-substituted allylic alcohols with activated isocyanates is reported. The reorganization of bonds is highly dependent on the electron density of the aromatic ring and the nature of isocyanate used. This metal-free tandem reaction from branched allyl alcohols initiated by a carbamoylation reaction and followed by a sigmatropic rearrangement thus offers a new access to (E)-cinnamyl and conjugated (E,E)-diene carbamates, such as N-acyl and N-sulfonyl derivatives. A computational study was conducted in order to rationalize this phenomenon, and a rearrangement progress kinetic analysis was performed.

Experimental and computational studies on dendrimers possessing a Fe(porphyrin) catalytic core and polyether dendritic arms show that these macromolecules promote efficiently the (2+1) cycloaddition between a model alkene and diazomethane. The reaction is kinetically efficient and competitive with smaller catalysts. Lower generations of dendrimers exhibit a normal hyperbolic kinetic behaviour, whereas third- and fourth-generation dendrimers show a sigmoidal kinetic profile, compatible with cooperative effects most likely due to aggregation phenomena. This behaviour resembles that observed for Fe(porphyrin) containing biomolecules such as cytochromes and haemoglobin.

NMR-based techniques are supposed to be incapable of distinguishing pure crystalline chemical enantiomers. However, through systematic studies of cross-polarization magic angle spinning (CP-MAS) NMR in a series of amino acids, we have found a rather unexpected behavior in the intensity pattern of optical isomers in hydrogen/nitrogen nuclear polarization transfer that would allow the use of CP NMR as a nondestructive enantioselective detection technique. In all molecules considered, the d isomer yields higher intensity than the l form, while the chemical shift for all nuclei involved remains unchanged. We attribute this striking result to the onset of electron spin polarization, accompanying bond charge polarization through a chiral center, a secondary mechanism for polarization transfer that is triggered only in the CP experimental setup. Electron spin polarization is due to the chiral-induced spin selectivity effect (CISS), which creates an enantioselective response, analogous to the one involved in molecular recognition and enantiospecific separation with achiral magnetic substrates. This polarization influences the molecular magnetic environment, modifying the longitudinal relaxation time T1 of 1H, and ultimately provoking the observed asymmetry in the enantiomeric response.

A series of Cu(I), Ag(I), and Au(I) complexes incorporating a new family of imidazopyridin-3-ylidene ligands substituted by a diphenylpyrrolidino group at N(1) and aryl groups at C(5) has been synthesized and their structures determined by X-ray diffraction analysis. This structural study has revealed an extremely high steric protection of the metal center by the bulky heterobicyclic carbenes, while the inversion at the exocyclic N(sp3) atom provides a remarkable flexibility.

Platinum complexes modified with a chiral non-racemizing SPO preligand 1 have been applied in the hydration of aromatic nitriles. [Pt(1)3Cl]Cl formed readily from Pt(COD)Cl2. The chiral secondary phosphine oxide complex showed moderate activity in the hydration of para- and meta-substituted benzonitriles, but failed in converting the ortho-substituted derivatives. The hydride complex PtH(PR2OH)(PR2O–H⋯OR2P) (PR2OH = 1) formed from Pt(PPh3)4 and 1, and the cationic complex derived from [Pt(1)3Cl]Cl via direct chloride abstraction with AgNO3 were proven to be considerably more active, allowing us to extend the scope to the hydration of ortho-substituted aromatic nitriles, including axially chiral [1,1′-binaphthalene]-2,2′-dicarbonitrile. In the hydration of the racemic dinitrile, successful kinetic resolution has been achieved. The catalysts derived from non-racemizing 1 are the first chiral transition metal–SPO complexes that provide kinetic resolution in the hydration of a racemic chiral nitrile.

A novel catalytic system based on covalently modified DNA is described., A novel catalytic system based on covalently modified DNA is described. This catalyst promotes 1,3-dipolar reactions between azomethine ylides and maleimides. The catalytic system is based on the distortion of the double helix of DNA by means of the formation of Pt(ii) adducts with guanine units. This distortion, similar to that generated in the interaction of DNA with platinum chemotherapeutic drugs, generates active sites that can accommodate N-metallated azomethine ylides. The proposed reaction mechanism, based on QM(DFT)/MM calculations, is compatible with thermally allowed concerted (but asynchronous) [π4s + π2s] mechanisms leading to the exclusive formation of racemic endo-cycloadducts.

Organocatalysis is becoming an important tool in polymer science because of its versatility and specificity. To date a limited number of organic catalysts have demonstrated the ability to promote stereocontrolled polymerizations. In this work we report one of the first examples of chirality transfer from a catalyst to a polymer in the organocatalyzed ring-opening polymerization (ROP) of rac-lactide (rac-LA). We have polymerized rac-LA using the diastereomeric densely substituted amino acids (2S,3R,4S,5S)-1-methyl-4-nitro-3,5-diphenylpyrrolidine- 2-carboxylic acid (endo-6) and (2S,3S,4R,5S)-1-methyl-4- nitro-3,5-diphenylpyrrolidine-2-carboxylic acid (exo-6), combined with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a cocatalyst. Both diastereoisomers not only showed the ability to synthesize enriched isotactic polylactide with a Pm higher than 0.90 at room temperature but also were able to preferentially promote the polymerization of one of the isomers (L or D) with respect to the other. Thus, exo-6 preferentially polymerized Llactide, whereas endo-6 preferred D-lactide as the substrate. Density functional theory calculations were conducted to investigate the origins of this unique stereocontrol in the polymerization, providing mechanistic insight and explaining why the chirality of the catalyst is able to define the stereochemistry of the monomer insertion. Financial support of this research by the MINECO (CTQ2016-80375-P, Consolider CTQ2016-81797-REDC, SUSPOL, and FDI 16507), the Gobierno Vasco/Eusko Jaurlaritza (Grants IT673-13 and IT618-13), the University of the Basque Country UPV/EHU (UFI 11/22 QOSYC), and the European Commission (SUPSOL-EJD 642671) is gratefully acknowledged. A.S.-S. is thankful for the Postdoctoral Funding for Doctoral Research Staff Improvement Grant from the Basque Government.

Both (5R)- and (5S)-1,7-diazaspiro[4.4]nonan-6-ones are obtained via a sequence of interrupted and completed stepwise (3 + 2) cycloadditions between azomethine ylides and π-deficient alkenes. The only source of chirality along the whole process is an enantiopure ferrocenyl pyrrolidine catalytic ligand. When the starting imine incorporates two aryl groups or one aryl group with one electron-releasing substituent, the reaction between the azomethine ylide and the alkene stops at the first step, leading to the corresponding Michael adduct. When imines derived from p-methoxybenzaldehyde are used, the corresponding syn-α-amino-γ-nitro ester is obtained with almost complete enantiocontrol. In contrast, imines derived from benzophenone lead to the corresponding anti analogue. From this interrupted (3 + 2) cycloaddition, cis- and trans-α-amino-γ-lactams can be obtained via hydrogenation of the nitro group followed by in situ cyclization. Imines derived from these latter compounds are the precursors of N-metalated azomethine ylides from which up to four new chiral centers can be generated via completed (3 + 2) cycloaddition reactions with full regio- and diastereocontrol. Cis- and trans-γ-lactams lead to opposite bis-spiropyrrolidine enantiomers. Therefore, both enantiomeric series of spiro compounds can be obtained by means of the same catalytic system. The potential of these rigid, densely substituted homochiral compounds in medicinal chemistry is briefly described.

The direct functionalization of aromatic C-H bonds by carbene insertion from diazocompounds catalyzed by gold complexes with N-heterocyclic ligands is described. The reaction is completely selective toward the Csp2-H bonds, other Csp3-H bonds remaining unreacted. A study with a several NHC ligands in Au(I) and Au(III) complexes has been performed. A potential application in profen derivatives has also been developed, DGI (CTQ2008-00042BQU and Consolider Ingenio 2010, Grant CSD2006-0003) and Junta de Andalucía (P07-FQM-02870)

New C- ansa -zirconocene complexes containing methoxythiophenolate and mercaptophenolate ligands have been synthesized and characterized. The reaction of (HSC 6 H 4 - n -OMe) ( n = 2, 3 or 4) with [Zr{( t -Bu)HC(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Me 2 ] ( 1 ) led to the formation of monosubstituted complexes [Zr{( t -Bu)HC(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Me(κ,S-SC 6 H 4 - n -OMe)] ( n = 2 ( 2 ); n = 3 ( 3 )) and the disubstituted complex [Zr{( t -Bu)HC(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}(κ,S-SC 6 H 4 -4-OMe) 2 ] ( 4 ). The complexes [Zr{(R)HC(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}(κ,O-OC 6 H 4 -4-SH) 2 ] (R = t -Bu ( 6 ); R = CH 2 CH CH 2 ( 7 )) and [Zr(η 5 -C 5 H 4 ) 2 (OC 6 H 4 - n -SH) 2 ] ( n = 3 ( 9 ); n = 4 ( 10 )) have been synthesized using the corresponding dimethyl zirconocene and mercaptophenol. However, the reaction of [Zr{( t -Bu)HC(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Cl 2 ] ( 11 ) with 4-mercaptophenol in the presence of NEt 3 led to the formation of the first example of a homoleptic six-coordinate mercaptophenolate complex of zirconium, namely [HNEt 3 ] 2 [Zr(κ,O-OC 6 H 4 -4-SH) 6 ] ( 12 ). Complex 12 can be obtained in higher yield by the reaction of ZrCl 4 with six equivalents of 4-mercaptophenol and NEt 3. The reaction of 12 with [Zr(η 5 -C 5 H 4 ) 2 Cl 2 ] gave the unexpected disubstituted complex [Zr(η 5 -C 5 H 4 ) 2 (OC 6 H 4 -4-SH) 2 ] ( 10 ). The molecular structures of 4 and 12 have been determined by single-crystal X-ray diffraction studies.

The allyl-substituted group 4 metal complexes [M{(R)CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Cl 2 ] [M = Ti, R = CH 2 CH CH 2 , ( 2 ); R = CH 2 C(CH 3 ) CH 2 ( 3 ); M = Zr, R = CH 2 CH CH 2 ( 4 ), R = CH 2 C(CH 3 ) CH 2 ( 5 )] have been synthesized by the reaction of allyl ansa -magnesocene derivatives and the tetrachloride salts of the corresponding transition metal. The dialkyl complexes [ M ( R ) CH ( η 5 - C 5 Me 4 ) ( η 5 - C 5 H 4 ) R 2 ′ ] [M = Ti, R = CH 2 =CHCH 2 , R′ = Me ( 6 ), R′ = CH 2 Ph ( 7 ); R = CH 2 C(CH 3 ) CH 2 , R′ = Me ( 8 ), R′ = CH 2 Ph ( 9 ); M = Zr, R = CH 2 CH CH 2 , R′ = Me ( 10 ), R′ = CH 2 Ph ( 11 ); R = CH 2 C(CH 3 ) CH 2 , R′ = Me ( 12 ), R′ = CH 2 Ph ( 13 )] have been synthesized by the reaction of the corresponding ansa -metallocene dichloride complexes 2–5 and two molar equivalents of the alkyl Grignard reagent. Compounds 2–5 reacted with H 2 under catalytic conditions (Wilkinson’s catalyst or Pd/C) to give the hydrogenation products [M{(R)CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Cl 2 ] [M = Ti and R = CH 2 CH 2 CH 3 ( 14 ) or R = CH 2 CH(CH 3 ) 2 ( 15 ); M = Zr and R = CH 2 CH 2 CH 3 ( 16 ) or R = CH 2 CH(CH 3 ) 2 ( 17 )]. The reactivity of 2–5 has also been tested in hydroboration and hydrosilylation reactions. The hydroboration reactions of 3 , 4 and 5 with 9-borabicyclo[3.3.1]nonane (9-BBN) yielded the complexes [M{(9-BBN)CH 2 CH(R)CH 2 CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Cl 2 ] [M = Ti and R = H ( 18 ); M = Zr and R = H ( 19 ) or R = CH 3 ( 20 )]. The reaction with the silane reagents HSiMe 2 Cl gave the corresponding [M{ClMe 2 SiCH 2 CHRCH 2 CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Cl 2 ] [M = Ti and R = H ( 21 ); M = Zr and R = H ( 22 ) or R = CH 3 ( 23 )]. The reaction of 22 with t -BuMe 2 SiOH produced a new complex [Zr{ t -BuMe 2 SiOSi(Me 2 )CH 2 CH 2 CH 2 CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Cl 2 ] ( 24 ) through the formation of Si–O–Si bonds. On the other hand, reactivity studies of some zirconocene complexes were carried out, with the insertion reaction of phenyl isocyanate (PhNCO) into the zirconium–carbon σ-bond of [Zr{( n -Bu)CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )} 2 Me 2 ] ( 25 ) giving [{( n -Bu)CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )]}Zr{Me{κ 2 -O,N-OC(Me)NPh}] as a mixture of two isomers 26a–b . The reaction of [Zr{( n -Bu)(H)C(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}(CH 2 Ph) 2 ] ( 27 ) with CO also provided a mixture of two isomers [{( n -Bu)CH(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )]}Zr(CH 2 Ph){κ 2 -O,C-COCH 2 Ph}] 28a–b . The molecular structures of 4 , 11 , 16 and 17 have been determined by single-crystal X-ray diffraction studies.

Both (5R)- and (5S)-1,7-diazaspiro[4.4]nonan-6-ones are obtained via a sequence of interrupted and completed stepwise (3 + 2) cycloadditions between azomethine ylides and π-deficient alkenes. The only source of chirality along the whole process is an enantiopure ferrocenyl pyrrolidine catalytic ligand. When the starting imine incorporates two aryl groups or one aryl group with one electron-releasing substituent, the reaction between the azomethine ylide and the alkene stops at the first step, leading to the corresponding Michael adduct. When imines derived from p-methoxybenzaldehyde are used, the corresponding syn-α-amino-γ-nitro ester is obtained with almost complete enantiocontrol. In contrast, imines derived from benzophenone lead to the corresponding anti analogue. From this interrupted (3 + 2) cycloaddition, cis- and trans-α-amino-γ-lactams can be obtained via hydrogenation of the nitro group followed by in situ cyclization. Imines derived from these latter compounds are the precursors of N-metalated azomethine ylides from which up to four new chiral centers can be generated via completed (3 + 2) cycloaddition reactions with full regio- and diastereocontrol. Cis- and trans-γ-lactams lead to opposite bis-spiropyrrolidine enantiomers. Therefore, both enantiomeric series of spiro compounds can be obtained by means of the same catalytic system. The potential of these rigid, densely substituted homochiral compounds in medicinal chemistry is briefly described.

The dialkyl complexes, [ Zr { R ( H ) C ( η 5 - C 5 Me 4 ) ( η 5 - C 5 H 4 ) } R 2 ′ ] (R = Pr i , R′ = Me ( 2a ), CH 2 Ph ( 3a ); R = Bu n , R′ = Me ( 2b ), CH 2 Ph ( 3b ); R = Bu t , R′ = Me ( 2c ), CH 2 Ph ( 3c ); R = Ph, R′ = Me ( 2d ), CH 2 Ph ( 3d )), have been synthesized by the reaction of the ansa -metallocene dichloride complex, [Zr{R(H)C(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}Cl 2 ] (R = Pr i ( 1a ), Bu n ( 1b ), Bu t ( 1c ), Ph ( 1d )), and two molar equivalents of the alkyl Gringard reagent. The insertion reaction of the isocyanide reagent, CNC 6 H 3 Me 2 -2,6, into the zirconium–carbon σ-bond of 2 gave the corresponding η 2 -iminoacyl derivatives, [Zr{R(H)C(η 5 -C 5 Me 4 )(η 5 -C 5 H 4 )}{η 2 -MeC NC 6 H 3 Me 2 -2,6}Me] (R = Pr i ( 4a ), Bu n ( 4b ), Bu t ( 4c ), Ph ( 4d )). The molecular structures of 1b , 1c and 3b have been determined by single-crystal X-ray diffraction studies.

This communication describes the synthesis and structural characterization of a potassium fulvene-substituted cyclopentadienyl compound which acts as a synthon in the facile preparation of ansa-metallocene complexes with variable substitution at the bridging atom.

We examined the ability of TpxM (Tpx = hydrotris(pyrazolyl)borate ligand; M = Cu and Ag) and IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene; M = Cu, Ag, Au) complexes as catalyst precursors for the cross-coupling of diazo compounds. Experimental data showed that the metal centre can be tuned with the appropriate selection of the ligand to yield either the homo- or hetero-coupling (cross-coupling) products. A computational study of the reaction mechanism allowed the rationalization of the experimental reactivity patterns, and the identification of the key reaction step controlling the selectivity: the initial reaction between the metallocarbene intermediate and one of the diazo compounds. This journal is © 2013 The Royal Society of Chemistry.

A novel hybrid dendrimer (TRANSGEDEN) that combines a conjugated rigid polyphenylenevinylene (PPV) core with flexible polyamidoamine (PAMAM) branches at the surface was synthesized and characterized. The potential of this material as a nonviral gene delivery system was also examined, and it was observed that dendriplexes formed by TRANSGEDEN and small interfering ribonucleic acids (siRNAs) can be incorporated into >90% of neuronal cells without any toxicity up to a dendrimer concentration of 3 μM. TRANSGEDEN was used to deliver a specific siRNA to rat cerebellar granular neurons (CGNs) to knock down the cofilin-1 protein. Cofilin-1 removal partially protects CGNs from N-methyl D-aspartate (NMDA)-mediated neuronal death.