ChemPlusChem最新文献

Au single atoms and clusters were stabilized on Mg-Al layered double hydroxide nanoparticles (LDH NPs), and the obtained Au@LDH NPs were supported on SiO₂ and CeO₂. After hydrogen reduction, Au single atoms were found together with Au clusters on LDH/SiO₂. In contrast to Au single-atom catalysts which are deposited in metal vacancies of oxide supports, the LDH NPs stabilize very small Au species despite the absence of metal vacancies. The obtained Au(0)@LDH/SiO₂ catalyzed aerobic oxidation of alcohols, and Au single atoms maintained after the reaction. Given that only Au NPs were observed on bulk LDH, the abundant surface OH group of LDH NPs would contribute to stabilize Au, resulting in higher activity than Au/LDH-bulk. After calcination to transform LDH to mixed metal oxide (MMO), the obtained Au(0)@MMO/SiO₂ also exhibited high catalytic activity. Moreover, Au(0)@LDH/CeO₂ exhibited higher activity and excellent selectivity for hydrogenation of 4-nitrostyrene to 4-aminostyrene than conventional Au catalysts such as Au/CeO₂ and Au/TiO₂. We demonstrated that Au size can be minimized using LDH NPs, exhibiting high catalytic performance. The basic surface OH groups of LDH would be also beneficial for deprotonation of alcohols and heterolytic dissociation of H₂ in the catalytic reactions.

Organic compounds bearing one or more carbocycles in their molecular structure have a discernible presence in all major classes of organic products of industrial significance. However, sourcing carbocyclic compounds from exhaustible, anthropogenic carbon (e. g., petroleum) raises serious concerns about sustainability in the chemical industries. This review discusses recent advances in the renewable synthesis of carbocyclic compounds from biomass components following catalytic pathways. The mechanistic insights, process optimizations, green metrics, and alternative synthetic strategies of carbocyclic compounds have been detailed. Moreover, the renewable syntheses of carbocycles have been assessed against their existing synthetic routes from petroleum for better perspectives on their sustainability and technological preparedness. This work will assist the researchers in acquiring updated information on the sustainable synthesis of carbocyclic compounds from various biomass components, comprehending the research gaps, and developing superior synthetic processes for their commercial production.

N. Hussain, A. Gogoi, R. Sarma, P. Sharma, A. Barras, R. Boukherroub, R. Saikia, P. Sengupta, and M. Das, “Reduced Graphene Oxide Nanosheets Decorated with Au Nanoparticles as an Effective Bactericide: Investigation of Biocompatibility and Leakage of Sugars and Proteins,” ChemPlusChem 79, no. 12 (2014): 1774–1784, https://doi.org/10.1002/cplu.201402240.

This Expression of Concern is for the above article, published online on 2 October 2014, in Wiley Online Library (wileyonlinelibrary.com), and has been published by agreement between the journal′s Editor-in-Chief, Axel Straube; Chemistry Europe; and Wiley-VCH GmbH, following an investigation from Wiley's Integrity in Publishing Group. The Expression of Concern has been agreed due to concerns raised by a third party after publication regarding the similarity of images in Figure 9 and the underlying data that they represent. The authors shared their original data, but were unable to provide a satisfactory explanation to the concerns. An investigation by the CNRS and Université Lille is ongoing. The journal is issuing this Expression of Concern because the concerns regarding the integrity of the data and the results presented cannot be resolved at this time.

The Co(salen) ([LCo(II)]) mediated hydrofunctionalization of alkenes is a highly significant method for forming enantioselective products. In this work, we conducted comprehensive computational investigations to gain insights of the reaction mechanism. The orbital analysis and intrinsic bond orbital analysis (IBO) were utilized to unravel the flow of electrons during the progress of the reaction. We explored various spin state surfaces to understand the possible pathways for the reaction. Initially, [LCo(II)] reacts with an oxidant tertbutyl peroxybenzoate, yielding [LCo(III)OC(O)Ph] and [LCo(III)O^tBu]. Subsequently, [LCo(III)OC(O)Ph] reacts with silane to form cobalt hydride ([LCo(III)H]), with the triplet spin state surface being the preferred pathway, featuring an energy barrier of 14.2 kcal mol^-1. IBO analysis across this step revealed that it involves the transfer of hydrogen as a hydride. Subsequently, the [LCo(III)H] complex in a triplet spin state undergoes a minimum energy crossing point (MECP) to transition into the singlet spin state, representing its most stable configuration. The [LCo(III)H] complex further reacts with styrene via hydrogen atom transfer on the singlet spin state surface, followed by oxidation and subsequent reaction with indole on the doublet spin surface to yield the hydrofunctionalized product. This work also explores potential enantioselective steps in the reaction.

Black phosphorus is a two-dimensional layer material with promising applications due to its many excellent physicochemical properties, including high carrier mobility, ambipolar field effect and unusual in-plane anisotropy. Currently, BP has been widely used in biomedical engineering, photocatalysis, semiconductor devices, and energy storage electrode materials. However, the unique structure of BP makes it highly chemically active, leading to its easy oxidation and degradation in air, which limits its practical applications. Recently, researchers have proposed a number of initiatives that can address the environmental instability of BP, and the application of these physical and chemical passivation techniques can effectively enhance the environmental stability of BP, including four modification methods: covalent functionalization, non-covalent functionalization, surface coordination, physical encapsulation and edge passivation. This review highlights the mechanisms of the above modification techniques in addressing the severe instability of BP in different application scenarios, as well as the advantages and disadvantages of each method. This review can provide guidance for more researchers in studying the marvellous properties of BP and accelerate the practical application of BP in different fields.

The reaction of cyanogen azide with strained-ring containing primary and secondary amines led to the isolation of energetic molecules deriving their energy content from both strained rings as well as aminotetrazoles. Azo-coupling of these materials afforded novel high-nitrogen energetic materials of very high sensitivity. All compounds were chemically characterized by IR, NMR, single-crystal X-ray crystallography, and high-resolution mass spectrometry. Their impact and friction sensitivities were experimentally determined, and their energetic performances were calculated.

The challenges in the fuel cell industry lie in the cost, performance, and durability of the electrode components, especially the platinum-based catalysts. Alloying has been identified as an effective strategy to reduce the cost of the catalyst and increase its efficiency and durability. So far, most studies focused on the design of PtM bimetallic nanocatalyst, where M is a transition metal. The resulting PtM materials show higher catalytic activity, but their stability remained challenging. In addition, most of the transition metals M are expensive or low abundant. Tin (Sn) has gained attention as alloying element due to its versatility in manufacturing both anode and cathode electrodes. If used as anode catalyst, it is able to overcome poisoning from CO and related intermediates. As cathode catalyst, it improves the kinetics of the oxygen reduction reaction (ORR). Additionally, Sn is an abundant and cheap element. The current contribution outlines the state of the art on the alloy and shape effect on PtSn activity and stability, demonstrating its high potential to develop cheaper, more efficient and durable catalysts for fuel-cell electrodes. Additionally, in situ analytical and spectroscopic studies can shed light on the elementary steps involved in the use of PtSn catalytic systems. Finally, this intriguing material can be used as a parent system for the synthesis of high-entropy-alloys and intermetallics materials.

An efficiency of delocalization in strongly conjugated systems remains an important factor crucial for modulation of the optical properties directly correlated with its range. An ortho-substituted phenylene derivative bearing electron donating/accepting functionality was built-in a fully unsaturated macrocyclic system with a global delocalization of a diatropic and/or a paratropic current. A precisely located structural modification influence observed behaviour in spectroscopic parameters that are only slightly recognizable in 4n+2 systems but showing a significant influence on the reduced derivatives with a contribution of 4n π-electrons delocalization path.

Pt-based intermetallics are regarded as highly efficient electrocatalysts for oxygen reduction reaction (ORR). However, Pt-based intermetallics with different Pt: M atomic ratios have different atomic arrangements and crystal structures, which will change the electronic structure and coordination environment of Pt, thus affecting the electrocatalytic activity. In this work, we prepared L1₂-Pt₃Co and L1₀-PtCo intermetallic catalysts by modulating the molar ratio of Pt and Co precursors using a thermal annealing method. The mass activity (MA) of L1₀-PtCo is 0.52 A mg^-1 _Pt at 0.9 V, which is 1.44 times larger than that of L1₂-Pt₃Co (0.36 A mg^-1 _Pt). In addition, the MA of L1₀-PtCo decreases by 17.31 % after 10,000 CV cycles, which is smaller than that of L1₂-Pt₃Co (25.00 % loss in MA), showing excellent structural stability. Theoretical calculations reveal that compared to L1₂-Pt₃Co, L1₀-PtCo has more electrons transferred to the Pt sites, which further optimizes the electronic structure of Pt and reduces the d-band center, leading to the increase of the electrocatalytic performance. This work provides new insights into the study of Pt-based intermetallics with different Pt: M ratios, which is helpful for the screening and preparation of high-performance Pt-based intermetallics.

The Protein Data Bank (PDB) was scrutinized for the presence of noncovalent O ⋅ ⋅ ⋅ Al Triel Bonding (TrB) interactions, involving protein residues (e. g. GLU and GLN), adenosine/guanine diphosphate moieties (ADP and GDP), water molecules and two aluminum fluorides (AlF₃ and AlF₄ ^-). The results were statistically analyzed, revealing a vast number of O ⋅ ⋅ ⋅ Al contacts in the active sites of phosphoryl transfer enzymes, with a marked directionality towards the Al σ-/π-hole. The physical nature of the TrBs studied herein was analyzed using Molecular Electrostatic Potential (MEP) maps, the Quantum Theory of Atoms in Molecules (QTAIM), the Non Covalent Interaction plot (NCIplot) visual index and Natural Bonding Orbital (NBO) studies. As far as our knowledge extends, it is the first time that O ⋅ ⋅ ⋅ Al TrBs are analyzed within a biological context, participating in protein trapping mechanisms related to phosphoryl transfer enzymes. Moreover, since they are involved in the stabilization of aluminum fluorides inside the protein's active site, we believe the results reported herein will be valuable for those scientists working in supramolecular chemistry, catalysis and rational drug design.