Iron promoted end-on dinitrogen-bridging in heterobimetallic complexes of uranium and lanthanides.

End-on binding of dinitrogen to low valent metal centres is common in transition metal chemistry but remains extremely rare in f-elements chemistry. In particular, heterobimetallic end-on N2 bridged complexes of lanthanides are unprecedented despite their potential relevance in catalytic reduction of dinitrogen. Here we report the synthesis and characterization of a series of N2 bridged heterobimetallic complexes of U(iii), Ln(iii) and Ln(ii) which were prepared by reacting the Fe dinitrogen complex [Fe(depe)2(N2)] (depe = 1,2-bis(diethylphosphino)-ethane), complex A with [MIII{N(SiMe3)2}3] (M = U, Ce, Sm, Dy, Tm) and [LnII{N(SiMe3)2}2], (Ln = Sm, Yb). Despite the lack of reactivity of the U(iii), Ln(iii) and Ln(ii) amide complexes with dinitrogen, the end-on dinitrogen bridged heterobimetallic complexes [{Fe(depe)2}(µ-η1:η1-N2)(M{N(SiMe3)2}3)], 1-M (M = U(iii), Ce(iii), Sm(iii), Dy(iii) and Tm(iii)), [{Fe(depe)2}(µ-η1:η1-N2)(Ln{N(SiMe3)2}2)], 1*-Ln (Ln = Sm(ii), Yb(ii)) and [{Fe(depe)2(µ-η1:η1-N2)}2{SmII{N(SiMe3)2}2}], 3 could be prepared. The synthetic method used here allowed to isolate unprecedented end-on bridging N2 complexes of divalent lanthanides which provide relevant structural models for the species involved in the catalytic reduction of dinitrogen by Fe/Sm(ii) systems. Computational studies showed an essentially electrostatic interaction of the end-on bridging N2 with both Ln(iii) and Ln(ii) complexes with the degree of N2 activation correlating with their Lewis acidity. In contrast, a back-bonding covalent contribution to the U(iii)-N2Fe bond was identified by computational studies. Computational studies also suggest that end-on binding of N2 to U(iii) and Ln(ii) complexes is favoured for the iron-bound N2 compared to free N2 due to the higher N2 polarization.

The therapeutic relationship from the perspective of patients and nurses in the first days of admission: A cross-sectional study in acute mental health units.

The therapeutic relationship (TR) is essential in mental health nursing care and plays a fundamental role in the understanding and treatment of the patient's health status. Despite being a bidirectional construct, limited evidence is available to shed light on this issue in mental health units and even less so in the first days of admission. This study aimed to examine the association and differences between nurses' and patients' perspectives on the establishment of the therapeutic relationship in acute mental health units during the first days of hospitalization. A cross-sectional study was carried out in 12 Spanish mental health units. Data were collected from patients and nurses using the Working Alliance Inventory-Short (WAI-S) questionnaire. A total of 234 cases were analysed, including 234 patients and 58 nurses. The results showed a positive association between nurses' and patients' perspectives on the therapeutic relationship, but also revealed significant differences on each WAI-S dimension. Nurses assigned higher scores compared to patients on the perception of the quality of the therapeutic relationship. The dimensions with the greatest weight from the patients' perspective regarding the quality of the therapeutic relationship were the perception of greater agreement on goals and tasks among nurses. This study demonstrates the importance of establishing shared goals and tasks with nurses from the first days of hospitalization to improve the quality of the therapeutic relationship as perceived by patients. These findings underline the need to consider the different perspectives of both parties to promote a high-quality therapeutic relationship.

Metabolic syndrome, adiposity, diet, and emotional eating are associated with oxidative stress in adolescents.

Background: Metabolic syndrome (MS), a condition related to adiposity and oxidative stress, can develop in adolescence, a critical stage in life that impacts health in adulthood. However, there is scarce scientific research about the relationship between lifestyle factors, emotion management, and oxidative stress in this phase of life. Aim: To analyze whether nutritional parameters, lifestyle factors, emotion management, and MS in adolescents are associated with oxidative stress measured by the biomarker 8-isoprostane. Methods: A cross-sectional study was carried out in 132 adolescents (48.5% girls, aged 12 ± 0.48 years) and data were collected on nutritional parameters (anthropometric measurements, biochemical analyzes, and blood pressure), lifestyle factors (physical activity, sleep, and diet), and emotion management (self-esteem, emotional eating, and mood). 8-isoprostane was analyzed in spot urine samples. The study population was categorized in three groups (healthy, at-risk, and with MS) using the International Diabetes Federation definition of MS in adolescents. To capture more complex interactions, a multiple linear regression was used to analyze the association between 8-isoprostane and the aforementioned variables. Results: Urinary 8-isoprostane levels were significantly higher in the MS group compared to the healthy group (1,280 ± 543 pg./mg vs. 950 ± 416 pg./mg respectively). In addition, univariable analysis revealed positive significant associations between 8-isoprostane and body mass index, waist circumference, waist-to-height ratio, body fat percentage, blood lipid profile and glucose, emotional eating, and refined cereal intake. Conversely, a negative significant association was found between 8-isoprostane and sleep duration and fish intake. The multiple linear regression analysis revealed associations between 8-isoprostane and LDL-c (ß = 0.173 value of p = 0.049), emotional eating (low ß = 0.443, value of p = 0.036; high ß = 0.152, value of p = 0.470), refined cereal intake (ß =0.191, value of p = 0.024), and fish intake (ß = -0.187, value of p = 0.050). Conclusion: The MS group, LDL-c, emotional eating, and high refined cereals and low fish intakes were associated with higher levels of oxidative stress in an adolescent population.

Effect of moderate beer consumption (with and without ethanol) on cardiovascular health in postmenopausal women.

BACKGROUND: The main aim of this 2-year non-randomized parallel controlled clinical pilot trial was to evaluate the long-term effect of a moderate daily intake of beer (with and without alcohol) on cardiovascular health in postmenopausal women. A total of 34 participants were grouped into three study arms: 16 were administered alcoholic beer, 6 consumed non-alcoholic beer, and 12 were in the control group. Changes in glucose metabolism, lipid profile, liver enzymes, anthropometric measurements, body composition, and blood pressure variables were monitored. Data on medical history, diet, and exercise were collected, and gustatory capacities were determined. RESULTS: Moderate consumption of beer, both alcoholic and non-alcoholic, seemed to have positive effects on biochemical indicators of cardiovascular health in postmenopausal women, with 660 mL day-1 of non-alcoholic beer reducing low-density lipoprotein cholesterol blood levels, and 330 mL day-1 of alcoholic beer increasing high-density lipoprotein cholesterol. The evolution of changes in android and gynoid fat percentage and their ratio differed significantly between study groups, which was attributable to either the interventions or the disparity between groups regarding the time elapsed since menopause onset. Iso-α-acids recognition threshold could be involved in intervention group election, whereas the sensory phenotypes studied were not associated with alcohol drinking frequency. CONCLUSIONS: Moderate beer consumption was found to improve the lipid profile of postmenopausal women, although their effects in preventing cardiometabolic alterations deserve further research (trial registration number: ISRCTN13825020; https://doi.org/10.1186/ISRCTN13825020). © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Unveiling the Latent Reactivity of Cp* Ligands (C5Me5-) toward Carbon Nucleophiles on an Iridium Complex.

The divergent reactivity of the cationic iridium complex [(η5-C5Me5)IrCl(PMe2ArDipp2)]+ (ArDipp2 = C6H3-2,6-(C6H3-2,6-iPr2)2) toward organolithium and Grignard reagents is described. The noninnocent behavior of the Cp* ligand, a robust spectator in the majority of stoichiometric and catalytic reactions, was manifested by its unforeseen electrophilic character toward organolithium reagents LiMe, LiEt, and LinBu. In these unconventional transformations, the metal center is only indirectly involved by means of the Ir(III)/Ir(I) redox cycle. In the presence of less nucleophilic organolithium reagents, the Cp* ligand also exhibits noninnocent behavior undergoing facile deprotonation, which is also concomitant with the reduction of the metal center. In turn, the weaker alkylating agents EtMgBr and MeMgBr effectively achieve the alkylation of the metal center. These reactive iridium(III) alkyls partake in subsequent reactions: while the ethyl complex undergoes ß-H elimination, the methyl derivative releases methane by a remote C-H bond activation. Computational studies, including the quantum theory of atoms in molecules (QTAIM), support that the preferential activation of the non-benzylic C-H bonds takes place via sigma-bond metathesis.

Polarized Au(I)/Rh(I) bimetallic pairs cooperatively trigger ligand non-innocence and bond activation.

The combination of molecular metallic fragments of contrasting Lewis character offers many possibilities for cooperative bond activation and for the disclosure of unusual reactivity. Here we provide a systematic investigation on the partnership of Lewis basic Rh(I) compounds of type [(η5-L)Rh(PR3)2] (η5-L = (C5Me5)- or (C9H7)-) with highly congested Lewis acidic Au(I) species. For the cyclopentadienyl Rh(I) compounds, we demonstrate the non-innocent role of the typically robust (C5Me5)- ligand through migration of a hydride to the Rh site and provide evidence for the direct implication of the gold fragment in this unusual bimetallic ligand activation event. This process competes with the formation of dinuclear Lewis adducts defined by a dative Rh → Au bond, with selectivity being under kinetic control and tunable by modifying the stereoelectronic and chelating properties of the phosphine ligands bound to the two metals. We provide a thorough computational study on the unusual Cp* non-innocent behavior and the divergent bimetallic pathways observed. The cooperative FLP-type reactivity of all bimetallic pairs has been investigated and computationally examined for the case of N-H bond activation in ammonia.

Ligand Postsynthetic Functionalization with Fluorinated Boranes and Implications in Hydrogenation Catalysis.

The incorporation of boron functionalities into transition-metal catalysts has become a promising strategy to improve catalytic performance, although their synthesis typically entails the preparation of sophisticated bifunctional ligands. We report here the facile and direct postsynthetic functionalization of rhodium(I) compound [(η5-C9H7)Rh(PPh3)2] (1) by treatment with perfluorinated boranes. Borane addition to 1 results in an unusual C(sp2)-H hydride migration from the indenyl ligand to the metal with the concomitant formation of a C-B bond. In the case of Piers' borane [HB(C6F5)2], this is followed by a subsequent hydride migration that leads to an unprecedented 1,2-hydrogen shift reminiscent of Milstein's cooperative dearomatization pathways. Computational investigations provide a mechanistic picture for the successive hydride-migration steps, which enriches the non-innocent chemistry of widespread indenyl ligands. Moreover, we demonstrate that the addition of Piers' borane is highly beneficial for catalysis, increasing catalyst efficiency up to 3 orders of magnitude.

Inter-individual characteristics on basic taste recognition thresholds in a college-aged cohort: potential predictive factors.

Studying nutritional status from the perspective of taste sensitivity, rather than only dietary patterns, may provide new insights into the role of taste receptor signaling in the development of metabolic-associated diseases. In this cross-sectional study, we investigated the possible influence of sociodemographic (sex and smoking habit) and clinical variables (dental cavities, missing teeth, sinusitis, rhinitis, body mass index and metabolic high prevalence family antecedent diseases) on tastant (sucrose, monosodium glutamate, sodium chloride, citric acid, quinine, sinigrin, phenylthiocarbamide) recognition thresholds (RTs) in a college-aged cohort (n = 397). Predictive models for the tastant RTs were generated and a higher sucrose RT was found in females than in males, while sinusitis and rhinitis explained sucrose and sodium chloride RTs. Smoking habit was not an important predictive factor of taste sensitivity, although its long-term influence on RTs remains unclear. Additionally, a positive correlation was found between all the tastant RTs studied. Although results did not show a clear pattern, the statistical approach employed should prove useful in future studies of predictors of taste sensitivity.

Effect of moderate beer consumption (with and without ethanol) on osteoporosis in early postmenopausal women: Results of a pilot parallel clinical trial.

Introduction: Osteoporosis is a chronic progressive bone disease characterized by low bone mineral density (BMD) and micro-architectural deterioration of bone tissue, leading to an increase in bone fragility and the risk of fractures. A well-known risk factor for bone loss is postmenopausal status. Beer may have a protective effect against osteoporosis associated with its content of silicon, polyphenols, iso-α-acids and ethanol, and its moderate consumption may therefore help to reduce bone loss in postmenopausal women. Methods: Accordingly, a 2-year controlled clinical intervention study was conducted to evaluate if a moderate daily intake of beer with (AB) or without alcohol (NAB) could have beneficial effects on bone tissue. A total of 31 postmenopausal women were assigned to three study groups: 15 were administered AB (330 mL/day) and six, NAB (660 mL/day), whereas, the 10 in the control group refrained from consuming alcohol, NAB, and hop-related products. At baseline and subsequent assessment visits, samples of plasma and urine were taken to analyze biochemical parameters, and data on medical history, diet, and exercise were collected. BMD and the trabecular bone score (TBS) were determined by dual-energy X-ray absorptiometry. Markers of bone formation (bone alkaline phosphatase [BAP] and N-propeptide of type I collagen [PINP]) and bone resorption (N-telopeptide of type I collagen [NTX] and C-telopeptide of type I collagen [CTX]) were determined annually. Results: Bone formation markers had increased in the AB and NAB groups compared to the control after the 2-year intervention. However, the evolution of BMD and TBS did not differ among the three groups throughout the study period. Discussion: Therefore, according to the findings of this pilot study, moderate beer intake does not seem to have a protective effect against bone loss in early post-menopausal women.

Homogeneous Electrocatalytic Reduction of CO2 by a CrN3O Complex: Electronic Coupling with a Redox-Active Terpyridine Fragment Favors Selectivity for CO.

Electrocatalyst design and optimization strategies continue to be an active area of research interest for the applied use of renewable energy resources. The electrocatalytic conversion of carbon dioxide (CO2) is an attractive approach in this context because of the added potential benefit of addressing its rising atmospheric concentrations. In previous experimental and computational studies, we have described the mechanism of the first molecular Cr complex capable of electrocatalytically reducing CO2 to carbon monoxide (CO) in the presence of an added proton donor, which contained a redox-active 2,2'-bipyridine (bpy) fragment, CrN2O2. The high selectivity for CO in the bpy-based system was dependent on a delocalized CrII(bpy•-) active state. Subsequently, we became interested in exploring how expanding the polypyridyl ligand core would impact the selectivity and activity during electrocatalytic CO2 reduction. Here, we report a new CrN3O catalyst, Cr(tpytbupho)Cl2 (1), where 2-(2,2':6',2″-terpyridin-6-yl)-4,6-di-tert-butylphenolate = [tpytbupho]-, which reduces CO2 to CO with almost quantitative selectivity via a different mechanism than our previously reported Cr(tbudhbpy)Cl(H2O) catalyst. Computational analyses indicate that, although the stoichiometry of both reactions is identical, changes in the observed rate law are the combined result of a decrease in the intrinsic ligand charge (L3X vs L2X2) and an increase in the ligand redox activity, which result in increased electronic coupling between the doubly reduced tpy fragment of the ligand and the CrII center. The strong electronic coupling enhances the rate of protonation and subsequent C-OH bond cleavage, resulting in CO2 binding becoming the rate-determining step, which is an uncommon mechanism during protic CO2 reduction.

Inverse potential scaling in co-electrocatalytic activity for CO2 reduction through redox mediator tuning and catalyst design.

Electrocatalytic CO2 reduction is an attractive strategy to mitigate the continuous rise in atmospheric CO2 concentrations and generate value-added chemical products. A possible strategy to increase the activity of molecular systems for these reactions is the co-catalytic use of redox mediators (RMs), which direct reducing equivalents from the electrode surface to the active site. Recently, we demonstrated that a sulfone-based RM could trigger co-electrocatalytic CO2 reduction via an inner-sphere mechanism under aprotic conditions. Here, we provide support for inner-sphere cooperativity under protic conditions by synthetically modulating the mediator to increase activity at lower overpotentials (inverse potential scaling). Furthermore, we show that both the intrinsic and co-catalytic performance of the Cr-centered catalyst can be enhanced by ligand design. By tuning both the Cr-centered catalyst and RM appropriately, an optimized co-electrocatalytic system with quantitative selectivity for CO at an overpotential (η) of 280 mV and turnover frequency (TOF) of 194 s-1 is obtained, representing a three-fold increase in co-catalytic activity at 130 mV lower overpotential than our original report. Importantly, this work lays the foundation of a powerful tool for developing co-catalytic systems for homogeneous electrochemical reactions.

Association of phenylthiocarbamide perception with anthropometric variables and intake and liking for bitter vegetables.

Phenylthiocarbamide (PTC) sensitivity, a sensory trait mediated by the bitter taste receptor 38 (TAS2R38), has been described as a promising biomarker of health status or disease risk. The aim of this cross-sectional study was to evaluate the influence of PTC phenotypes on (1) individual anthropometric and clinical history variables; (2) other basic taste recognition thresholds (RTs), and (3) the hedonic perception and habitual intake of Brassicaceae vegetables in a young adult population (18.9 ± 1.7 years old). The PTC phenotype was determined by the quantitative measure of the PTC recognition threshold (non-tasters, 24.1%; tasters, 52.3%; and super tasters, 23.6%). No significant differences in smoking habits, oral and nasal disorders, family antecedents of diseases related to metabolic syndrome, and Brassicaceae vegetable hedonic perception and consumption were found between the PTC phenotype groups. The average BMI of super-taster females and males was significantly lower compared to non-tasters. In addition, the PTC taster status was a predictor of lower scores for other basic taste RTs. Overall, the defined PTC super-taster cohort could be differentiated from the non-tasters by variables related to weight control such as BMI and sucrose RT.

Mediated Inner-Sphere Electron Transfer Induces Homogeneous Reduction of CO2 via Through-Space Electronic Conjugation.

The electrocatalytic reduction of CO2 is an appealing method for converting renewable energy sources into value-added chemical feedstocks. We report a co-electrocatalytic system for the reduction of CO2 to CO comprised of a molecular Cr complex and dibenzothiophene-5,5-dioxide (DBTD) as a redox mediator, which achieves high activity (TOF=1.51-2.84×105  s-1 ) and quantitative selectivity. Under aprotic or protic conditions, DBTD produces a co-electrocatalytic response with 1 by coordinating trans to the site of CO2 binding and mediating electron transfer from the electrode with quantitative efficiency for CO. This assembly is reliant on through-space electronic conjugation between the π frameworks of DBTD and the bpy fragment of the catalyst ligand, with contributions from dispersive interactions and weak sulfone coordination.

A dicoordinate gold(I)-ethylene complex.

The use of the exceptionally bulky tris-2-(4,4'-di-tert-butylbiphenylyl)phosphine ligand allows the isolation and complete characterization of the first dicoordinate gold(I)-ethylene adduct, filling a missing fundamental piece on the organometallic chemistry of gold. Besides, the bonding situation of this species has been investigated by means of state-of-the-art Density Functional Theory (DFT) calculations indicating that π-backdonation plays a minor role compared with tricoordinate analogues.

DFT Study on the Electrocatalytic Reduction of CO2 to CO by a Molecular Chromium Complex.

A variety of molecular transition metal-based electrocatalysts for the reduction of carbon dioxide (CO2) have been developed to explore the viability of utilization strategies for addressing its rising atmospheric concentrations and the corresponding effects of global warming. Concomitantly, this approach could also meet steadily increasing global energy demands for value-added carbon-based chemical feedstocks as nonrenewable petrochemical resources are consumed. Reports on the molecular electrocatalytic reduction of CO2 mediated by chromium (Cr) complexes are scarce relative to other earth-abundant transition metals. Recently, our group reported a Cr complex that can efficiently catalyze the reduction of CO2 to carbon monoxide (CO) at low overpotentials. Here, we present new mechanistic insight through a computational (density functional theory) study, exploring the origin of kinetic selectivity, relative energetic positioning of the intermediates, speciation with respect to solvent coordination and spin state, as well as the role of the redox-active bipyridine moiety. Importantly, these studies suggest that under certain reducing conditions, the formation of bicarbonate could become a competitive reaction pathway, informing new areas of interest for future experimental studies.

Reductive C-C Coupling from Molecular Au(I) Hydrocarbyl Complexes: A Mechanistic Study.

Organometallic gold complexes are used in a range of catalytic reactions, and they often serve as catalyst precursors that mediate C-C bond formation. In this study, we investigate C-C coupling to form ethane from various phosphine-ligated gem-digold(I) methyl complexes including [Au2(µ-CH3)(PMe2Ar')2][NTf2], [Au2(µ-CH3)(XPhos)2][NTf2], and [Au2(µ-CH3)(tBuXPhos)2][NTf2] {Ar' = C6H3-2,6-(C6H3-2,6-Me)2, C6H3-2,6-(C6H2-2,4,6-Me)2, C6H3-2,6-(C6H3-2,6-iPr)2, or C6H3-2,6-(C6H2-2,4,6-iPr)2; XPhos = 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl; tBuXPhos = 2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl; NTf2 = bis(trifluoromethyl sulfonylimide)}. The gem-digold methyl complexes are synthesized through reaction between Au(CH3)L and Au(L)(NTf2) {L = phosphines listed above}. For [Au2(µ-CH3)(XPhos)2][NTf2] and [Au2(µ-CH3)(tBuXPhos)2][NTf2], solid-state X-ray structures have been elucidated. The rate of ethane formation from [Au2(µ-CH3)(PMe2Ar')2][NTf2] increases as the steric bulk of the phosphine substituent Ar' decreases. Monitoring the rate of ethane elimination reactions by multinuclear NMR spectroscopy provides evidence for a second-order dependence on the gem-digold methyl complexes. Using experimental and computational evidence, it is proposed that the mechanism of C-C coupling likely involves (1) cleavage of [Au2(µ-CH3)(PMe2Ar')2][NTf2] to form Au(PR2Ar')(NTf2) and Au(CH3)(PMe2Ar'), (2) phosphine migration from a second equivalent of [Au2(µ-CH3)(PMe2Ar')2][NTf2] aided by binding of the Lewis acidic [Au(PMe2Ar')]+, formed in step 1, to produce [Au2(CH3)(PMe2Ar')][NTf2] and [Au2(PMe2Ar')]+, and (3) recombination of [Au2(CH3)(PMe2Ar')][NTf2] and Au(CH3)(PMe2Ar') to eliminate ethane.

Dual Behavior of Long-Chain Fatty Acids and Their Cyclooxygenase/Lipoxygenase Metabolites on Human Intestinal Caco-2 Cell Growth.

Etiology of colorectal cancer (CRC) is related, at least in part, with nutritional profile and epidemiological data indicating a key role of dietary fat on CRC pathogenesis. Moreover, inflammation and eicosanoids produced from arachidonic acid might have a pivotal role in CRC development. However, the effect of specific fatty acids (FAs) on intestinal epithelial cell growth is not completely studied now. By this reason, the aim of this work is to unravel the effect of different saturated and unsaturated long-chain fatty acids (LCFA) and some LCFA metabolites on CRC cell line growth and their possible mechanisms of action. Our results demonstrated that oleic acid is a potent mitogenic factor to Caco-2 cells, at least in part, through 10-hydroxy-8-octadecenoic synthesized by lipoxigenase pathway, whereas polyunsaturated FAs such as eicosapentaenoic (EPA) acid has a dual behavior effect depending on its concentration. A high concentration, EPA induced apoptosis through intrinsic pathway, whereas at low concentration induced cell proliferation that could be related to the synthesis of eicosanoids such as prostaglandin E3 and 12-hydroxyeicosapentaenoic acid and the subsequent induction of mitogenic cell signaling pathways (ERK 1/2, CREB, p38α). Thus, this study contributes to understand the complicated relationship between fat ingest and CRC.

Mechanistic insight into initiation and regioselectivity in the copolymerization of epoxides and anhydrides by Al complexes.

Pentacoordinate Al catalysts comprising bipyridine (bpy) and phenanthroline (phen) backbones were synthesized and their catalytic activity in epoxide/anhydride copolymerization was investigated and compared to (t-Busalph)AlCl. Stoichiometric reactions of tricyclic anhydrides with Al alkoxide complexes produced ring-opened products that were characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography, revealing key regio- and stereochemical aspects.