Metal-ligand cooperation facilitates bond activation and catalytic hydrogenation with zinc pincer complexes

We thank the European Research Council (ERC AdG 692775) for support of this research. M.R. acknowledges the Zuckerman STEM Leadership Program for a research fellowship. S.K. acknowledges the Sustainability and Energy Research Initiative (SAERI) Weizmann Institute of Science for a research fellowship. A. K. is thankful to the Feinberg Graduate School for the Senior Postdoctoral Fellowship.A series of PNP zinc pincer complexes capable of bond activation via aromatization/dearomatization metal-ligand cooperation (MLC) were prepared and characterized. Reversible heterolytic N-H and H-H bond activation by MLC is shown, in which hemilability of the phosphorus linkers plays a key role. Utilizing this zinc pincer system, base-free catalytic hydrogenation of imines and ketones under relatively mild conditions is demonstrated. A detailed mechanistic study supported by computation implicates the key role of MLC in facili-tating effective catalysis. This approach offers a new strategy for (de)hydrogenation and other catalytic transformations mediated by zinc and other main group metals.PostprintPeer reviewe

Formation of Alkanes by Aerobic Carbon–Carbon Bond Coupling Reactions Catalyzed by a Phosphovanadomolybdic Acid

The valorization of alkanes is possible via carbon–carbon coupling reactions. A series of dialkyl cobalt complexes [(RCH_2)_2Co^(III)(bpy)_2]ClO_4 (R = H, Me, Et, and Ph) were reacted with the H_5PV_2Mo_(10)O_(40) polyoxometalate as a catalyst, leading to a selective oxidative carbon–carbon bond coupling reaction. The reaction is initiated by electron transfer from [(RCH_2)_2Co^(III)(bpy)_2]^+ to H_5PV^V_2Mo_(10)O_(40) to yield an intermediate [(RCH_2)_2Co^(IV)(bpy)_2]^(2+)–H_5PV^(IV)V^VMo_(10)O_(40), as identified by a combination of EPR and X-ray photoelectron spectroscopy experiments. The reaction is catalytic with O_2 as terminal oxidant representing an aerobic C–C bond coupling reaction

Metal-driven folding and assembly of a minimal β-sheet into a 3D-porous honeycomb framework

This research was supported by the DST Inspire Faculty Fellowship (No. DST/INSPIRE/04/2020/002499), and National Institute of Pharmaceutical Education and Research, S. A. S. Nagar. S. B. thanks SERB, Govt. of India for the Ramanujan Fellowship (ref. no. RJF/2022/000042) and Ashoka University.In contrast to short helical peptides, constrained peptides, and foldamers, the design and fabrication of crystalline 3D frameworks from the β-sheet peptides are rare because of their high self-aggregation propensity to form 1D architectures. Herein, we demonstrate the formation of a 3D porous honeycomb framework through the silver coordination of a minimal β-sheet forming a peptide having terminal metal coordinated 4- and 3-pyridyl ligands.Peer reviewe

Nuevos datos acerca de los repertorios teatrales en el primer catálogo de «El peregrino en su patria»

En este artículo se muestra cómo los títulos que contienen los repertorios de los autores de comedias presentes en El peregrino en su patria de 1604 están dispuestos según un orden cronológico, aunque con algunos matices y no pocas excepciones. Además, se amplían los repertorios descubiertos por Thornton Wilder y se afina la fecha de composición de varias obras, prestando especial atención a textos que se han perdido, como La perdición de España, La gobernadora, La gran pintora, La bella gitana o La toma de Álora. Finalmente, el presente artículo pretende mostrar de un modo práctico cómo una base de datos digital como el Diccionario biográfico de actores del teatro clásico español (DICAT) puede resultar de gran ayuda a la hora de resolver algunos de los problemas clásicos de la filología en general y del teatro del Siglo de Oro en particular.This paper shows that the plays contained in the repertoire of the autores de comedias which appear in El peregrino en su patria (1604) are organised chronologically, although there are some nuances and exceptions. The article also expands the repertoire discovered by Thornton Wilder and sets the date of composition for some plays, paying special attention to lost texts such as La perdición de España, La gobernadora, La gran pintora, La bella gitana or La toma de Álora. Finally, this paper attempts to show in a practical way that a database such as the Diccionario biográfico de actores del teatro clásico español (DICAT) can be extremely helpful when it comes to dealing with some of the philology's classical problems in general and those of the theatre of the Golden Age in particular

3 years of liraglutide versus placebo for type 2 diabetes risk reduction and weight management in individuals with prediabetes: a randomised, double-blind trial

Background: Liraglutide 3·0 mg was shown to reduce bodyweight and improve glucose metabolism after the 56-week period of this trial, one of four trials in the SCALE programme. In the 3-year assessment of the SCALE Obesity and Prediabetes trial we aimed to evaluate the proportion of individuals with prediabetes who were diagnosed with type 2 diabetes. Methods: In this randomised, double-blind, placebo-controlled trial, adults with prediabetes and a body-mass index of at least 30 kg/m2, or at least 27 kg/m2 with comorbidities, were randomised 2:1, using a telephone or web-based system, to once-daily subcutaneous liraglutide 3·0 mg or matched placebo, as an adjunct to a reduced-calorie diet and increased physical activity. Time to diabetes onset by 160 weeks was the primary outcome, evaluated in all randomised treated individuals with at least one post-baseline assessment. The trial was conducted at 191 clinical research sites in 27 countries and is registered with ClinicalTrials.gov, number NCT01272219. Findings: The study ran between June 1, 2011, and March 2, 2015. We randomly assigned 2254 patients to receive liraglutide (n=1505) or placebo (n=749). 1128 (50%) participants completed the study up to week 160, after withdrawal of 714 (47%) participants in the liraglutide group and 412 (55%) participants in the placebo group. By week 160, 26 (2%) of 1472 individuals in the liraglutide group versus 46 (6%) of 738 in the placebo group were diagnosed with diabetes while on treatment. The mean time from randomisation to diagnosis was 99 (SD 47) weeks for the 26 individuals in the liraglutide group versus 87 (47) weeks for the 46 individuals in the placebo group. Taking the different diagnosis frequencies between the treatment groups into account, the time to onset of diabetes over 160 weeks among all randomised individuals was 2·7 times longer with liraglutide than with placebo (95% CI 1·9 to 3·9, p<0·0001), corresponding with a hazard ratio of 0·21 (95% CI 0·13–0·34). Liraglutide induced greater weight loss than placebo at week 160 (–6·1 [SD 7·3] vs −1·9% [6·3]; estimated treatment difference −4·3%, 95% CI −4·9 to −3·7, p<0·0001). Serious adverse events were reported by 227 (15%) of 1501 randomised treated individuals in the liraglutide group versus 96 (13%) of 747 individuals in the placebo group. Interpretation: In this trial, we provide results for 3 years of treatment, with the limitation that withdrawn individuals were not followed up after discontinuation. Liraglutide 3·0 mg might provide health benefits in terms of reduced risk of diabetes in individuals with obesity and prediabetes. Funding: Novo Nordisk, Denmark

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

The Constrained Maximal Expression Level Owing to Haploidy Shapes Gene Content on the Mammalian X Chromosome.

X chromosomes are unusual in many regards, not least of which is their nonrandom gene content. The causes of this bias are commonly discussed in the context of sexual antagonism and the avoidance of activity in the male germline. Here, we examine the notion that, at least in some taxa, functionally biased gene content may more profoundly be shaped by limits imposed on gene expression owing to haploid expression of the X chromosome. Notably, if the X, as in primates, is transcribed at rates comparable to the ancestral rate (per promoter) prior to the X chromosome formation, then the X is not a tolerable environment for genes with very high maximal net levels of expression, owing to transcriptional traffic jams. We test this hypothesis using The Encyclopedia of DNA Elements (ENCODE) and data from the Functional Annotation of the Mammalian Genome (FANTOM5) project. As predicted, the maximal expression of human X-linked genes is much lower than that of genes on autosomes: on average, maximal expression is three times lower on the X chromosome than on autosomes. Similarly, autosome-to-X retroposition events are associated with lower maximal expression of retrogenes on the X than seen for X-to-autosome retrogenes on autosomes. Also as expected, X-linked genes have a lesser degree of increase in gene expression than autosomal ones (compared to the human/Chimpanzee common ancestor) if highly expressed, but not if lowly expressed. The traffic jam model also explains the known lower breadth of expression for genes on the X (and the Z of birds), as genes with broad expression are, on average, those with high maximal expression. As then further predicted, highly expressed tissue-specific genes are also rare on the X and broadly expressed genes on the X tend to be lowly expressed, both indicating that the trend is shaped by the maximal expression level not the breadth of expression per se. Importantly, a limit to the maximal expression level explains biased tissue of expression profiles of X-linked genes. Tissues whose tissue-specific genes are very highly expressed (e.g., secretory tissues, tissues abundant in structural proteins) are also tissues in which gene expression is relatively rare on the X chromosome. These trends cannot be fully accounted for in terms of alternative models of biased expression. In conclusion, the notion that it is hard for genes on the Therian X to be highly expressed, owing to transcriptional traffic jams, provides a simple yet robustly supported rationale of many peculiar features of X's gene content, gene expression, and evolution

Crystal structure of disodium 2-amino-6-oxo-6,7-dihydro-1H-purine-1,7-diide heptahydrate

In the title compound, disodium 2-amino-6-oxo-6,7-dihydro-1H-purine-1,7-diide heptahydrate, 2Na+·C5H3N5O2−·7H2O, the structure is composed of alternating (100) layers of guanine molecules and hydrated Na+ ions. Within the guanine layer, the molecules are arranged in centrosymmetric pairs, with a partial overlap between the guanine rings. In this compound, guanine exists as the amino–keto tautomer from which deprotonation from N1 and N7 has occurred (purine numbering). There are no direct interactions between the Na+ cations and the guanine anions. Guanine molecules are linked to neighboring water molecules by O—H...N and O—H...O hydrogen bonds into a network structure

Methylene transfer from SnMe groups mediated by a rhodium(I) pincer complex: Sn-C, C-C, and C-H bond activation

The PCP-Rh(I) complex 1a based on the [1,3-phenylenebis(methylene)]bis(diisopropylphosphine) ligand reacts with [diazo(phenyl)methyl]trimethylstannane (2) at room temperature to give novel pincer-type phenyl(dimethylstannyl)methylene]hydrazinato complex 3a. The reaction sequence involves a unique combination of Sn-C bond cleavage, C-C bond formation, C-H activation and intramolecular deprotonation of a rhodium hydride intermediate, which results in methylene transfer from an SnMe group to the pincer system and PCP-chelate expansion. A methylene-transfer reaction was also demonstrated with tetramethyltin as the methylene source in the presence of KOC(CH(3))(3) at room temperature. The resulting unstable "chelate-expanded" Rh(I) complex [(C(10)H(5)(CH(2)PiPr(2))(2))(CH(2))Rh(L)] (L=N(2), THF; 4a) was isolated as its carbonyl derivative 5a. Heating 4a in benzene yielded an equimolar amount of toluene and 1a, which demonstrates the ability of the Rh(I) pincer complex to extract a methylene group from an unactivated alkyl tin substrate and transfer it, via C-C followed by C-H activation, to an arene. Use of fluorobenzene resulted in formation of fluorotoluene. Catalytic methylene-group transfer mediated by 1a was not possible, because of formation of o-xylylene complex 8 under the reaction conditions. Steric parameters play a decisive role in the reactivity with tin compounds; while iPrP derivative 1 a underwent facile reactions, tBuP complex 1b was inert