Silica-supported Fe/Fe–O nanoparticles for the catalytic hydrogenation of nitriles to amines in the presence of aluminium additives

The hydrogenation of nitriles to amines represents an important and frequently used industrial process due to the broad applicability of the resulting products in chemistry and life sciences. Despite the existing portfolio of catalysts reported for the hydrogenation of nitriles, the development of iron-based heterogeneous catalysts for this process is still a challenge. Here, we show that the impregnation and pyrolysis of iron(II) acetate on commercial silica produces a reusable Fe/Fe-O@SiO2 catalyst with a well-defined structure comprising the fayalite phase at the Si-Fe interface and alpha-Fe nanoparticles, covered by an ultrathin amorphous iron(III) oxide layer, growing from the silica matrix. These Fe/Fe-O core-shell nanoparticles, in the presence of catalytic amounts of aluminium additives, promote the hydrogenation of all kinds of nitriles, including structurally challenging and functionally diverse aromatic, heterocyclic, aliphatic and fatty nitriles, to produce primary amines under scalable and industrially viable conditions.Web of Science51292

Interface engineering of SRu-mC(3)N(4) heterostructures for enhanced electrochemical hydrazine oxidation reactions

Hydrazine oxidation in single-atom catalysts (SACs) could exploit the efficiency of metal atom utilization, which is a substitution for noble metal-based electrolysers that results in reduced overall cost. A well-established ruthenium single atom over mesoporous carbon nitride (SRu-mC(3)N(4)) catalyst is explored for the electro-oxidation of hydrazine as one of the model reactions for direct fuel cell reactions. The electrochemical activity observed with linear sweep voltammetry (LSV) confirmed that SRu-mC(3)N(4) shows an ultra-low onset potential of 0.88 V vs. RHE, and with a current density of 10 mA/cm(2) the observed potential was 1.19 V vs. RHE, compared with mesoporous carbon nitride (mC(3)N(4)) (1.77 V vs. RHE). Electrochemical impedance spectroscopy (EIS) and chronoamperometry (i-t) studies on SRu-mC(3)N(4) show a smaller charge-transfer resistance (R-Ct) of 2950 omega and long-term potential, as well as current stability of 50 h and 20 mA/cm(2), respectively. Herein, an efficient and enhanced activity toward HzOR was demonstrated on SRu-mC(3)N(4) from its synergistic platform over highly porous C3N4, possessing large and independent active sites, and improving the subsequent large-scale reaction.Web of Science1212art. no. 156

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Reusable Co-nanoparticles for general and selective N-alkylation of amines and ammonia with alcohols

A general cobalt-catalyzed N-alkylation of amines with alcohols by borrowing hydrogen methodology to prepare different kinds of amines is reported. The optimal catalyst for this transformation is prepared by pyrolysis of a specific templated material, which is generated in situ by mixing cobalt salts, nitrogen ligands and colloidal silica, and subsequent removal of silica. Applying this novel Co-nanoparticle-based material, >100 primary, secondary, and tertiary amines including N-methylamines and selected drug molecules were conveniently prepared starting from inexpensive and easily accessible alcohols and amines or ammonia.Web of Science13111711

Interface Engineering of SRu-mC3N4 Heterostructures for Enhanced Electrochemical Hydrazine Oxidation Reactions

Hydrazine oxidation in single-atom catalysts (SACs) could exploit the efficiency of metal atom utilization, which is a substitution for noble metal-based electrolysers that results in reduced overall cost. A well-established ruthenium single atom over mesoporous carbon nitride (SRu-mC3N4) catalyst is explored for the electro-oxidation of hydrazine as one of the model reactions for direct fuel cell reactions. The electrochemical activity observed with linear sweep voltammetry (LSV) confirmed that SRu-mC3N4 shows an ultra-low onset potential of 0.88 V vs. RHE, and with a current density of 10 mA/cm2 the observed potential was 1.19 V vs. RHE, compared with mesoporous carbon nitride (mC3N4) (1.77 V vs. RHE). Electrochemical impedance spectroscopy (EIS) and chronoamperometry (i-t) studies on SRu-mC3N4 show a smaller charge-transfer resistance (RCt) of 2950 Ω and long-term potential, as well as current stability of 50 h and 20 mA/cm2, respectively. Herein, an efficient and enhanced activity toward HzOR was demonstrated on SRu-mC3N4 from its synergistic platform over highly porous C3N4, possessing large and independent active sites, and improving the subsequent large-scale reaction

Intermetallic copper-based electride catalyst with high activity for C-H oxidation and cycloaddition of CO2 into epoxides

Inorganic electrides have been proved to be efficient hosts for incorporating transition metals, which can effectively act as active sites giving an outstanding catalytic performance. Here, it is demonstrated that a reusable and recyclable (for more than 7 times) copper-based intermetallic electride catalyst (LaCu0.67Si1.33), in which the Cu sites activated by anionic electrons with low-work function are uniformly dispersed in the lattice framework, shows vast potential for the selective C-H oxidation of industrially important hydrocarbons and cycloaddition of CO2 with epoxide. This leads to the production of value-added cyclic carbonates under mild reaction conditions. Importantly, the LaCu0.67Si1.33 catalyst enables much higher turnover frequencies for the C-H oxidation (up to 25 276 h(-1)) and cycloaddition of CO2 into epoxide (up to 800 000 h(-1)), thus exceeding most nonnoble as well as noble metal catalysts. Density functional theory investigations have revealed that the LaCu0.67Si1.33 catalyst is involved in the conversion of N-hydroxyphthalimide (NHPI) into the phthalimido-N-oxyl (PINO), which then triggers selective abstraction of an H atom from ethylbenzene for the generation of a radical susceptible to further oxygenation in the presence of O-2.Web of Science1838art. no. 220171

The hallmarks of copper single atom catalysts in direct alcohol fuel cells and electrochemical CO2 fixation

Single-atom catalysts (SACs) are highly enviable to exploit the utmost utilization of metallic catalysts; their efficiency by utilizing nearly all atoms to often exhibit high catalytic performances. To architect the isolated single atom on an ideal solid support with strong coordination has remained a crucial trial. Herein, graphene functionalized with nitrile groups (cyanographene) as an ideal support to immobilize isolated copper atoms G(CN)-Cu with strong coordination is reported. The precisely designed mixed-valence single atom copper (G(CN)-Cu) catalysts deliver exceptional conversions for electrochemical methanol oxidation (MOR) and CO2 reduction (CO2RR) targeting a "closed carbon cycle." An onset of MOR and CO2RR are obtained to be approximate to 0.4 V and approximate to-0.7 versus Ag/AgCl, respectively, with single active sites located in an unsaturated coordination environment, it being the most active Cu sites for both studied reactions. Moreover, G(CN)-Cu exhibited significantly lower resistivity and higher current density toward MOR and CO2RR than observed for reference catalysts.Web of Scienceart. no. 200182

Single Co-atoms as electrocatalysts for efficient hydrazine oxidation reaction

Single-atom catalysts (SACs) have aroused great attention due to their high atom efficiency and unprecedented catalytic properties. A remaining challenge is to anchor the single atoms individually on support materials via strong interactions. Herein, single atom Co sites have been developed on functionalized graphene by taking advantage of the strong interaction between Co2+ ions and the nitrile group of cyanographene. The potential of the material, which is named G(CN)-Co, as a SAC is demonstrated using the electrocatalytic hydrazine oxidation reaction (HzOR). The material exhibits excellent catalytic activity for HzOR, driving the reaction with low overpotential and high current density while remaining stable during long reaction times. Thus, this material can be a promising alternative to conventional noble metal-based catalysts that are currently widely used in HzOR-based fuel cells. Density functional theory calculations of the reaction mechanism over the material reveal that the Co(II) sites on G(CN)-Co can efficiently interact with hydrazine molecules and promote the N-H bond-dissociation steps involved in the HzOR.Web of Science1716art. no. 200647