Stereoselective Research Articles

A Targeted LC-MRM3 Proteomic Approach for the Diagnosis of SARS-CoV-2 Infection in Nasopharyngeal Swabs

Since its first appearance, severe acute respiratory syndrome coronavirus 2 quickly spread around the world and the lack of adequate PCR testing capacities, especially during the early pandemic, led the scientific community to explore new approaches such as mass spectrometry (MS). We developed a proteomics workflow to target several tryptic peptides of the nucleocapsid protein. A highly selective multiple reaction monitoring-cubed (MRM3) strategy provided a sensitivity increase in comparison to conventional MRM acquisition. Our MRM3 approach was first tested on an Amsterdam public health cohort (alpha-variant, 760 participants) detecting viral nucleocapsid protein peptides from nasopharyngeal swabs samples presenting a cycle threshold value down to 35 with sensitivity and specificity of 94.2% and 100.0%, without immunopurification. A second iteration of the MS-diagnostic test, able to analyze more than 400 samples per day, was clinically validated on a Leiden-Rijswijk public health cohort (delta-variant, 2536 participants) achieving 99.9% specificity and 93.1% sensitivity for patients with cycle threshold values up to 35. In this manuscript, we also developed and brought the first proof of the concept of viral variant monitoring in a complex matrix using targeted MS.

Detection of ascorbic acid by persistent luminescent nanoparticles based on CoOOH nanosheets modification.

Persistent luminescent nanomaterials (PLNPs) Zn0.8Ga2O4: Cr3+, Zr3+ with high brightness and good dispersion were prepared by hydrothermal method. The PLNPs were used as luminescent units, and CoOOH nanosheets were used as quenching agents. Based on the fluorescence internal filtering effect, the luminescence of PLNPs were effectively quenched by CoOOH modification on the surface of PLNPs. However, the introduction of ascorbic acid (AA) restored the luminescence of PLNPs and successfully achieved highly sensitive and selective detection of AA. This was due to a selective redox reaction between CoOOH and AA, in which CoOOH was reduced to Co2+. The degree of luminescence recovery of PLNPs showed a good linear relationship with AA concentration in the range 5-250 µM, with a detection limit of 0.72 µM. Therecovery of actualspikedsamples were 97.9-102.2%. This method isexpected to provide reference for the study of other redox substances in biological systems.

Acquisition of para-(1-methylcyclopentyl)phenol and its acylation reaction with acetyl- and benzoyl chlorides

The article is devoted to the study of phenol cycloalkylation reactions 1-methylcyclopentene in a in periodical action installation in the presence of zeolite-containing catalyst KN-30 and acylation reactions of obtained p-(1-methylcyclopentyl)phenol with acetyl and benzoyl chlorides in the presence of a ZnCl2 catalyst. First of all, the influence kinetic parameters (temperature, time, molar ratios starting components, the amount of catalyst) on the yield and selectivity reactions of cycloalkylation of phenol with 1-methylcyclopentene in the presence of catalyst KN-30 was investigated. In the found optimal conditions for the cycloalkylation reaction: temperature – 110 оС, time – 5 hours, molar ratio of phenol to MCF 1:1, amount of catalyst 12 %, yield of the target product – p-(1-methylcyclopentyl)phenol is 77.3 % (based on phenol), the selectivity of the target product is 92.6 %. Acylation reactions of the obtained p-(1-methylcyclopentyl)phenol with acetyl- and benzoyl chlorides were performed in the presence of anhydrous catalyst ZnCl2. In order to obtain effective conditions for acylation reactions, the influence of the reaction temperature, duration, and molar ratio of the starting components on the yield and selectivity of methylcyclopentylaceto- and benzophenones was studied. As a result, it was found that for acylation reactions of p-(1-methylcyclopentyl)phenol with acetyl and benzoyl chloride in the presence of a ZnCl2 catalyst, the reaction temperature is 140–150 оC, the duration should be 35–40 minutes, and the molar ratio phenol AC(BC) should be 1:2. Under these conditions, the yield of target products is 57.2–61.7 % (based on the taken alkylphenol).

Poly(2-isopropenyl-2-oxazoline) as a Versatile Functional Polymer for Biomedical Applications.

Functional polymers play an important role in various biomedical applications. From many choices, poly(2-isopropenyl-2-oxazoline) (PIPOx) represents a promising reactive polymer with great potential in various biomedical applications. PIPOx, with pendant reactive 2-oxazoline groups, can be readily prepared in a controllable manner via several controlled/living polymerization methods, such as living anionic polymerization, atom transfer radical polymerization (ATRP), reversible addition-fragmentation transfer (RAFT) or rare earth metal-mediated group transfer polymerization. The reactivity of pendant 2-oxazoline allows selective reactions with thiol and carboxylic group-containing compounds without the presence of any catalyst. Moreover, PIPOx has been demonstrated to be a non-cytotoxic polymer with immunomodulative properties. Post-polymerization functionalization of PIPOx has been used for the preparation of thermosensitive or cationic polymers, drug conjugates, hydrogels, brush-like materials, and polymer coatings available for drug and gene delivery, tissue engineering, blood-like materials, antimicrobial materials, and many others. This mini-review covers new achievements in PIPOx synthesis, reactivity, and use in biomedical applications.

Supporting Nano Catalysts for the Selective Hydrogenation of Biomass-derived Compounds.

The selective hydrogenation of biomass derivatives presents a promising pathway for the production of high-value chemicals and fuels, thereby reducing reliance on traditional petrochemical industries. Recent strides in catalyst nanostructure engineering, achieved through tailored support properties, have significantly enhanced the hydrogenation performance in biomass upgrading. A comprehensive understanding of biomass selective upgrading reactions and the current advancement in supported catalysts is crucial for guiding future processes in renewable biomass. This review aims to summarize the development of supported nanocatalysts for the selective hydrogenation of the US DOE's biomass platform compounds derivatives into valuable upgraded molecules. The discussion includes an exploration of the reaction mechanisms and conditions in catalytic transfer hydrogenation (CTH) and high-pressure hydrogenation. By thoroughly examining the tailoring of supports, such as metal oxide catalysts and porous materials, in nano-supported catalysts, we elucidate the promoting role of nanostructure engineering in biomass hydrogenation. This endeavor seeks to establish a robust theoretical foundation for the fabrication of highly efficient catalysts. Furthermore, the review proposes prospects in the field of biomass utilization and address application bottlenecks and industrial challenges associated with the large-scale utilization of biomass.

High-throughput screening of single-atom catalysts on 1 T-TMD for highly active and selective CO2 reduction reaction: Computational and machine learning insights

The study of transition metals and various possible surface compositions has sparked great interest in low-cost materials, which exhibit high activity and selectivity in catalysis. While various single-atom catalysts loaded on transition metal dichalcogenide (TMD) substrates with excellent CO2 reduction performance have been identified, the relationship between catalytic activity and the intrinsic properties of TMD single-atom catalysts remains unclear. Hence, a high-throughput first-principle computational approach is proposed to screen 24 transition metals anchored on 8 TMD monolayers to determine their catalytic activity in CO2RR. The results show that Fe@CoS2, Pt@TiTe2 and Co@CoS2 exhibit exceptional performances with low CO2RR limiting-potentials of −0.045 eV, 0.75 eV, and 0.54 eV, respectively, showcasing selective pathways towards formic acid (HCOOH), methane (CH4), and methanol (CH3OH). Employing the Sure Independence Screening and Sparsifying Operator method(SISSO), key descriptors linking the performance of single-atom catalysts with their intrinsic features are identified, providing insights for the discovery of superior CO2RR catalysts. Moreover, it was observed that a feature of the anchored single atom, the difference between covalent radius and atomic radius (CR-R), is associated with multiple crucial reaction steps, exhibiting a strong linear relationship with the charge transfer of *COOH. This work not only identifies promising CO2RR catalysts but also establishes a predictive framework for screening catalysts based on their intrinsic properties, paving the way for future advancements in CO2 reduction research.

Ultralow Catalytic Loading for Optimised Electrocatalytic Performance of AuPt Nanoparticles to Produce Hydrogen and Ammonia

AbstractThe hydrogen evolution and nitrite reduction reactions are key to producing green hydrogen and ammonia. Antenna–reactor nanoparticles hold promise to improve the performances of these transformations under visible‐light excitation, by combining plasmonic and catalytic materials. However, current materials involve compromising either on the catalytic activity or the plasmonic enhancement and also lack control of reaction selectivity. Here, we demonstrate that ultralow loadings and non‐uniform surface segregation of the catalytic component optimize catalytic activity and selectivity under visible‐light irradiation. Taking Pt−Au as an example we find that fine‐tuning the Pt content produces a 6‐fold increase in the hydrogen evolution compared to commercial Pt/C as well as a 6.5‐fold increase in the nitrite reduction and a 2.5‐fold increase in the selectivity for producing ammonia under visible light excitation relative to dark conditions. Density functional theory suggests that the catalytic reactions are accelerated by the intimate contact between nanoscale Pt‐rich and Au‐rich regions at the surface, which facilitates the formation of electron‐rich hot‐carrier puddles associated with the Pt‐based active sites. The results provide exciting opportunities to design new materials with improved photocatalytic performance for sustainable energy applications.

Ultralow Catalytic Loading for Optimised Electrocatalytic Performance of AuPt Nanoparticles to Produce Hydrogen and Ammonia.

The hydrogen evolution and nitrite reduction reactions are key to producing green hydrogen and ammonia. Antenna-reactor nanoparticles hold promise to improve the performances of these transformations under visible-light excitation, by combining plasmonic and catalytic materials. However, current materials involve compromising either on the catalytic activity or the plasmonic enhancement and also lack control of reaction selectivity. Here, we demonstrate that ultralow loadings and non-uniform surface segregation of the catalytic component optimize catalytic activity and selectivity under visible-light irradiation. Taking Pt-Au as an example we find that fine-tuning the Pt content produces a 6-fold increase in the hydrogen evolution compared to commercial Pt/C as well as a 6.5-fold increase in the nitrite reduction and a 2.5-fold increase in the selectivity for producing ammonia under visible light excitation relative to dark conditions. Density functional theory suggests that the catalytic reactions are accelerated by the intimate contact between nanoscale Pt-rich and Au-rich regions at the surface, which facilitates the formation of electron-rich hot-carrier puddles associated with the Pt-based active sites. The results provide exciting opportunities to design new materials with improved photocatalytic performance for sustainable energy applications.

Metallaphotoredox deuteroalkylation utilizing thianthrenium salts

Deuterium labeling compounds play a crucial role in organic and pharmaceutical chemistry. The synthesis of such compounds typically involves deuterated building blocks, allowing for the incorporation of deuterium atoms and functional groups into a target molecule in a single step. Unfortunately, the limited availability of synthetic approaches to deuterated synthons has impeded progress in this field. Here, we present an approach utilizing alkyl-substituted thianthrenium salts that efficiently and selectively introduce deuterium at the α position of alkyl chains through a pH-dependent HIE process, using D2O as the deuterium source. The resulting α-deuterated alkyl thianthrenium salts, which bear two deuterium atoms, exhibit excellent selectivity and deuterium incorporation in electrophilic substitution reactions. Through in situ formation of isotopically labelled alkyl halides, these thianthrenium salts demonstrate excellent compatibility in a series of metallaphotoredox cross-electrophile coupling with (hetero)aryl, alkenyl, alkyl bromides, and other alkyl thianthrenium salts. Our technique allows for a wide range of substrates, high deuterium incorporation, and precise control over the site of deuterium insertion within a molecule such as the benzyl position, allylic position, or any alkyl chain in between, as well as neighboring heteroatoms. This makes it invaluable for synthesizing various deuterium-labeled compounds, especially those with pharmaceutical significance.

Engineering single-atom catalysts on triazine-based covalent organic frameworks for enhanced photocatalytic performance in N2 reduction

The solar conversion of nitrogen to ammonia is a green, sustainable, and promising way to fix nitrogen. However, designing a photocatalyst with high activity, selectivity, and stability for the N2 reduction reaction (NRR) is challenging because of the slow inert activation of N2 and competitive hydrogen evolution reaction (HER). Herein, a single metal site anchored to a triazine-based covalent organic framework (Tr-COF) backbone (named TM@Tr-COF; TM = Fe, Co and Ni) is fabricated for high-performance catalytic N2 reduction. Density functional theory calculations show that the Fe@Tr-COF, Co@Tr-COF and Ni@Tr-COF can effectively activate N2 and reduce it to NH3 via the electron “acceptance–donation” process. Meanwhile, the NRR occurs via the enzymatic pathway on the Fe@Tr-COF, Co@Tr-COF and Ni@Tr-COF with a limiting potential of 0.38 V, 0.58 V and 0.54 V, respectively. Furthermore, the anchoring of Fe/Co/Ni on the Tr-COF allows the Tr-COF to be adjusted to the appropriate edge position and visible light-absorption region, indicating that the system may be a promising and efficient photocatalyst. Compared with other competitive reactions, the system exhibits high selectivity for NH3 production and inhibits competitive HERs. These findings have considerable implications for innovatively designing highly active single-atom catalysts supported by COFs.

Ammonia-free selective catalytic reduction of NO by coal-based activated carbon supported Cu-Mn oxides at low temperature

Selective catalytic reduction of ammonia is the most widely technology for removing NOx, but there were serious ammonia leakage and high temperature reaction. To overcome these limitations, a series of Cu and Mn metals supported on coal-based activated carbon (CuxMny/CAC) were synthesized, for ammonia-free catalytic reduction of NO at low temperature. The results demonstrated that Cu and/or Mn catalysts significantly improved low-temperature SCR performance and char-NO reaction selectivity when combined with CAC. In particular, Cu6Mn4/CAC showed excellent NO removal rate (100 %) and higher char-NO selectively (111.21 mg/g) at 290 ℃ under O2-rich condition. Characterization analyses revealed that Cu6Mn4/CAC had a larger BET surface area and preferable pore structure, and the synergistic effect mainly came from the redox cycle between CuOx and MnOy, as well as the interaction between Cu-Mn oxides and the CAC support. Cu-Mn metals promote the adsorption of NO and O2 in the char-NO process, leading to the generation of abundant surface adsorption oxygen species (O2-, O22-, and O-) and C(O) complex, which facilitated the char-NO reaction. Therefore, a mechanism for ammoniac-free selective catalytic reduction of NO by Cu6Mn4/CAC was proposed. These finding provide new insights for developing low-temperature ammonia-free denitrification technology and improving high-value utilization of coal resources.

Copper and silver nano-schiff base complexes: Efficient catalysts for triazole synthesis and antimicrobial assessment

1,2,3-Triazoles are one of the most important nitrogen-containing five-membered heterocycles and have a wide range of applications in pharmaceuticals, chemical biology, and industry. Therefore, the development of facile and straightforward methodology for the synthesis of 1,2,3-triazoles is of noteworthy interest. Click chemistry represents the most facile, easy and one pot reaction method to synthesize catalyzed azide–alkyne cycloaddition reaction. Nano-scaled bis(2‑hydroxy-1-naphthylmethylidene) ethane-1,2-diamine copperII [CuSB1] and nano-silver ethane-1,2-diamine bis(2-hydroxy-1-naphthylmethylidene) [AgHSB2] complexes where H2SB= 1,2-diamino ethane-N,N’-bis(2-hydroxy-1-naphthylmethylidene), were synthesized utilizing ultrasonic green method. The catalysts were examined by elemental analyses, molar conductance, and spectrophotometric tests. The optimized geometrical structures of H2SB, [CuSB1], [AgHSB2], and HOMO–LUMO representations were performed by Cluster calculations using DMOL3 program. TEM images showed narrower morphology and regular nanostructures of the catalysts. CuSB1] and [AgHSB2] exhibit efficient catalytic activity to prepare different triazoles (3–8). using single-pot selective cycloaddition reaction within very short time and excellent yield without presence of biproducts. The complexes [CuSB1], [AgHSB2] and the triazoles 3, 4, as representative examples, have efficient antimicrobial activity making them promising drugs for treating the bacterial and fungal infections.

Structural evolution in S-vacancy-rich Co@Co9S8 during selective benzyl alcohol electrooxidation reaction

Electrooxidation of organics using electrons as oxidants is a clean approach to produce commodity chemicals. However, designing an electrocatalyst with superior performance at low cell voltage remains a challenge. In this study, a series of VS-Co@Co9S8 electrocatalysts were fabricated by thermal reduction method using MOFs as templates. The catalytic oxidation performance and reaction mechanism of such specimens for benzyl alcohol were comprehensively analyzed by electrochemical measurement method and ex-situ structure characterization. The results show that Co@Co9S8-30 M has a unique three-dimensional (3D) micro cubic structure with abundant S vacancy (VS). These features accelerate the electrons and substrate transfer as well as provide plentiful active sites for benzyl alcohol electrooxidation reaction (BAOR). Consequently, the Co@Co9S8-30 M presented outstanding catalytic activity. The overpotential of 10 mA cm−2 (η10) was only 265.4 mV for BAOR. The conversion rate and benzoic acid selectivity were achieved to 72% and 90%, respectively. Particularly, the formation rate of benzoic acid was 7.247 mmol·gcat.−1·h−1. Moreover, the Co@Co9S8-30 M exhibited superior durability over 135 h. The coordination number of octahedral metal sites in Co9S8 did not match the number of Co 3 d orbital electrons, resulting in the weakening of bonding strength between Co and S elements. Thus, the Co@Co9S8 was reconstructed to Co3O4@CoOOH. Based on this assessment, the Co3O4@CoOOH was the active site of BAOR. This work provides theoretical guidance for the design of Co-based catalysts.

Recent Advances in the Use of Controlled Nanocatalysts in Methane Conversion Reactions

This study investigates the utilization of controlled nanocatalysts in methane conversion reactions, addressing the pressing need for the efficient utilization of methane as a feedstock for valuable chemicals and clean energy. The methods employed include a comprehensive review of recent advancements in nanocatalyst synthesis, characterization, and application, as well as the critical analysis of underlying mechanisms and controversies in methane activation and transformation. The main findings reveal significant progress in the design and synthesis of controlled nanocatalysts, enabling enhanced activity, selectivity, and stability in methane conversion reactions. Moreover, the study highlights the importance of resolving controversies surrounding metal–support interactions for rational catalyst design. Overall, the study underscores the pivotal role of nanotechnology in shaping the future of methane utilization and sustainable energy production, providing valuable insights for guiding future research directions and technological developments in this field.

Comparative study of catalytic conversion of glucose over γ-alumina supported tungsten oxide catalysts with controlling acidity

For the advancement of sustainable energy systems, biomass holds the potential to become a primary energy source worldwide. Glucose is one of the most economical and abundant carbohydrates, which can be converted to more value-added chemical feedstock. Here, a series of tungsten oxide catalysts supported on γ-alumina with varying tungsten content were synthesized using the wet impregnation method, and applied on the glucose conversion. The physicochemical properties of the prepared catalysts were investigated through powder X-ray diffraction, N2 sorption, scanning electron microscopy, UV-diffuse reflectance spectroscopy, and Raman spectroscopy. Pyridine-adsorption IR analysis was conducted to elucidate the acidic properties of the catalysts. As the loaded tungsten content increased, the concentration of Brønsted acid sites increased while the Lewis acid sites exhibited a decreasing trend. By controlling the acid concentration by the tungsten content, it was possible to adjust the optimal glucose conversion and the product selectivity in this cascade chemical reaction. When the tungsten content is too high, the Brønsted acid site is excessively present, and the resulting side reaction can be occurred. Here, we propose a catalyst design with appropriate acidity, which can obtain the target product with high yield.

Development of a Cryogenic Flow Reactor to Optimize Glycosylation Reactions Based on the Active Donor Intermediate.

The development of a continuous flow reactor for stereospecific glycosylation reactions with deoxy sugars is described. This apparatus that permits optimizing the selectivity of glycosylation reactions based on the stability of the activated intermediate is described. By coupling a flow apparatus with HPLC analysis, we can optimize the yield of TsCl-mediated β-linked deoxy sugar construction in a matter of hours. In all cases, results from continuous flow processing translate into improved results in batch-scale reactions, as demonstrated by competition experiments. This is the result of carrying out optimization to identify the ideal temperature for the reaction of the activated intermediate, as opposed to the initial activation conditions. Such an approach allows for the rapid development of highly selective glycosylation reactions in cases in which classical neighboring group participation is not possible.

Physicochemical reactions in e-waste recycling.

Electronic waste (e-waste) recycling is becoming a global concern owing to its immense quantity, hazardous character and the potential loss of valuable metals. The many processes involved in e-waste recycling stem from a mixture of physicochemical reactions, and understanding the principles of these reactions can lead to more efficient recycling methods. In this Review, we discuss the principles behind photochemistry, thermochemistry, mechanochemistry, electrochemistry and sonochemistry for metal recovery, polymer decomposition and pollutant elimination from e-waste. We also discuss how these processes induce or improve reaction rates, selectivity and controllability of e-waste recycling based on thermodynamics and kinetics, free radicals, chemical bond energy, electrical potential regulation and more. Lastly, key factors, limitations and suggestions for improvements of these physicochemical reactions for e-waste recycling are highlighted, wherein we also indicate possible research directions for the future.

Selective catalytic oxidation of DMF over Cu-Ce/H-MOR by modulating the surface active sites

Selective catalytic oxidation of the hazardous DMF exhaust gas presents a significant challenge in balancing oxidation activity and products selectivity (CO, NOx, N2, etc.). It is found that Cu/H-MOR demonstrates superior performance for DMF oxidation compared to CuO on other supports (γ-Al2O3, HY, ZSM-5) in terms of product selectivity and stability. The geometric and electronic structures of CuO active sites in Cu/H-MOR have been regulated by CeO2 promoter, leading to an increase in the ratio of active CuO (highly dispersed CuO and Cu+ specie). As a result, the oxidation activity and stability of the Cu/H-MOR catalyst were enhanced for DMF selective catalytic oxidation. However, excessive CuO or CeO2 content led to decreased N2 selectivity due to over-high oxidation activity. It is also revealed that Ce3+ species, active CuO species, and surface acid sites play a critical role in internal selective catalytic reduction reaction during DMF oxidation. The 10Cu-Ce/H-MOR (1/4) catalyst exhibited both high oxidation activity and internal selective catalytic reduction activity due to its abundance of active CuO specie as well as Ce3+ species and surface acid sites. Consequently, the 10Cu-Ce/H-MOR (1/4) catalyst demonstrated the widest temperature window for DMF oxidation with high N2 selectivity. These findings emphasize the importance of surface active sites modification for DMF selective catalytic oxidation.

Boosted scavenger-free photocatalytic H2O2 production over alkali-doped poly(heptazine imide) under controlled solution conditions

Photocatalysis renders appealing mechanisms for synthesizing hydrogen peroxide (H2O2) under ambient conditions; however, it still suffers from low efficiency due to the high kinetic barriers, low reaction selectivity, and severe recombination of photo-generated charge carriers. This study contributes to establishing a fundamental understanding of the influence of the solution environment, specifically the solution pH, on the photocatalytic performance of H2O2 production. By adjusting the solution environment from neutral to alkaline, the photocatalytic system, consisting of a prototype photocatalyst of alkali-doped poly(heptazine imide), exhibited a 9-fold increase in the production of H2O2, with an unprecedented rate of 6.78 gcat−1h−1. Mechanistic studies demonstrate that alkaline conditions can trigger the rarely occurring two-electron water oxidization, thus enabling H2O2 formation through both the oxygen reduction reaction and water oxidization pathways simultaneously. Moreover, the high pH condition also plays an important role in shifting the band edge of the photocatalyst and alleviating the photocatalytic decomposition of H2O2. These fundamental insights may provide guidelines for the development of superior photocatalytic systems.

Latest Developments of the Julia-Kocienski Olefination Reaction: Mechanistic Considerations.

Since its discovery, the Julia-Kocienski olefination reaction has over past 30 years become one of the key C-C connective methods that is used in late-stage natural product synthesis. The reaction proceeds under mild reaction conditions, with a wide substrate scope and functional group tolerance range and with high (E) selectivity. In this focused review, we discuss the reaction from a mechanistic point of view and disclose key features that play an important role in reaction selectivity. Finally, the mechanistic aspects of the newly developed modification of the Julia-Kocienski reaction, which allows the formation of both (E) and (Z) olefins from the same reaction partners, are discussed.