Attempts to form a tethered-N-heterocyclic Carbene Aluminium hydride complex resulted in the unexpected formation of a bicyclic N-heterocyclic aminal Aluminium hydride.

Abstract

Tethered N-heterocyclic carbenes (NHCs) are an emerging class of ligand, as they feature all the desirable aspects of NHCs (ease of synthesis, high tunabilty) but also enable metal-ligand cooperativity when combined with Lewis acidic metal centres due to the donor-acceptor nature of the complexes formed. Herein we report a simple ethoxy-tethered NHC for the stabilisation of Al(III) hydrides, resulting in the unexpected formation of a bicyclic N-heterocyclic aminal (1). Compound 1 behaves as a metal hydride, capable of reducing benzophenone and carbodiimide to yield compounds 2 and 3, respectively. Furthermore, we show that 1 behaves as an efficient catalyst in the dehydrocoupling of amine-boranes due to the hemi-labile nature of the supporting ligand.

There are more chances for interfacial engineering when Janus particles with different properties and compositions are spread out on the surface of a single objector. Janus particles are a new type of interfacial active material that combines the amphiphilic properties of molecular surfactants with the Pickering effect of uniform particles. Find out more in the review article written by Fuxin Liang and co-workers.

We report a heterogeneous photocatalytic system for the construction of valuable γ-amino acid scaffolds through the carboxylation of alkenes with the ambient CO₂. The system provides a green and sustainable methodology to the synthesis of amino acid derivatives in one-step with visible light.

Abstract

A metal-free heterogeneous protocol is established herein for the synthesis of value-added γ-amino acid scaffolds via carbocarboxylation of alkenes with CO₂ and alkylamines under visible light irradiation. The protocol shows broad substrate scope under mild reaction conditions and good stability of the catalyst for recycle tests. Moreover, the methodology could be feasible to the late-stage derivatization of several natural products, enriching the chemical arsenal for practical application.

Functionalization of unactivated C(sp³)−H bonds represents one of the most explored transformation in organic synthesis. This review highlights the most recent breakthroughs in the Iron-catalyzed functionalization of unactivated C(sp³)−H bonds.

Abstract

The use of iron as a core metal in catalysis has become a research topic of interest over the last few decades. The reasons are clear. Iron is the most abundant transition metal on Earth's crust and it is widely distributed across the world. It has been extracted and processed since the dawn of civilization. All these features render iron a noncontaminant, biocompatible, nontoxic, and inexpensive metal and therefore it constitutes the perfect candidate to replace noble metals (rhodium, palladium, platinum, iridium, etc.). Moreover, direct C−H functionalization is one of the most efficient strategies by which to introduce new functional groups into small organic molecules. The majority of organic compounds contain C(sp³)−H bonds. Given the enormous importance of organic molecules in so many aspects of existence, the utilization and bioactivity of C(sp³)−H bonds are of the utmost importance. This review sheds light on the substrate scope, selectivity, benefits, and limitations of iron catalysts for direct C(sp³)−H bond activations. An overview of the use of iron catalysis in C(sp³)−H activation protocols is summarized herein up to 2022.

Organic coatings were degraded via UV-generated sulfate radicals. The degradation allowed the restoration of the original surface properties on the substrate, offering the potential for substrate recycling. Furthermore, the applicability of this approach to the degradation of the adhesive layer existing between the substrate interfaces, underscoring its versatility.

Abstract

Degradation of organic coatings is essential for recycling valuable substrates. Despite the development of strategies for this purpose, the resulting degradations are typically constrained by the composition of the coating. This paper presents a simple strategy utilizing radicals induced by UV for the degradation of diverse organic coatings. The sulfate radicals, generated from UV-exposed ammonium persulfates, induce the degradation of various organic coatings, including layer-by-layer assembled coating composed of alginate and chitosan polymers as well as polydopamine coating. This strategy also facilitates the separation of two adhered substrates by degrading the adhesive polymer layer positioned between them. This novel approach enables the complete degradation of various organic coatings in aqueous conditions without imposing restrictions on their composition, leading to the recovery of the original surface properties of the substrate.

Diverse emission behaviors are demonstrated by investing the impact of protonated/deprotonated Carbon Dots and their interactions with solvents. Ultrafast spectroscopy reveals that the surface modification significantly affects the carrier relaxation rate and quantum yield, emphasizing a distinct preference for deprotonated surface structure in facilitating carrier radiation recombination

Abstract

The intricate nature of the surface structure of carbon dots (CDs) hinders a comprehensive understanding of their emission behavior. In this study, we employ two types of CDs created through acid-alkali treatments, one with surface protonation and the other with surface deprotonation, with the objective of investigating the impact of these surface modifications on carrier behavior using ultrafast spectroscopy techniques. TEM, XRD, FTIR and Raman spectra demonstrate the CDs’ structure, featuring graphitic core and abundant surface functional groups. XPS confirms the successful surface modifications of CDs via protonation and deprotonation. Ultrafast transient absorption (TA) spectroscopy reveals that deprotonation modification may decelerate the relaxation process, thereby increasing the visible PL quantum yields (PLQY). Conversely, protonation may accelerate the relaxation process due to the induced low-energy absorption band, resulting in self-absorption and reduced PLQY. Furthermore, TA analysis of CDs in mixed solvents with different proportions of ethanol shows the beneficial effect of ethanol in decelerating the relaxation process, leading to an increased PLQY of 33.7 % for deprotonated CDs and 22.1 % for protonated CDs. This study illuminates the intricate relationship between surface deprotonation/protonation modifications and carrier behavior in CDs, offering a potential avenue for the design of high-brightness CDs for diverse applications.

A simple catalytic process for the C−H arylation of (poly)flluoroarenes with aryl pinacol boronates mediated by a Pd/Ag system without added ligand is reported. This reaction can be carried out in air, generating unsymmetric biaryl products in up to 98 % yield. DFT calculations indicate that the presence of an electron-rich aryl ligand at Pd(II) intermediate reduces the energy barrier for the CMD process with C₆F₅H to give [Pd(DMF)₂(Ar)(C₆F₅)], and thus the desired cross-coupling product is obtained.

Abstract

We report the synergistic combination of Pd(OAc)₂ and Ag₂O for the oxidative C−H arylation of (poly)fluoroarenes with aryl pinacol boronates (Ar-Bpin) in DMF as the solvent. This procedure can be conducted easily in air, and without using additional ligands, to afford the fluorinated unsymmetrical biaryl products in up to 98 % yield. Experimental studies suggest that the formation of [PdL₂(C₆F₅)₂] in DMF as coordinating solvent does not take place under the reaction conditions as it is stable to reductive elimination and thus would deactivate the catalyst. Thus, the intermediate [Pd(DMF)₂(Ar_F)(Ar)] must be formed selectively to give desired arylation products. DFT calculations predict a low barrier (5.87 kcal/mol) for the concerted metalation deprotonation (CMD) process between C₆F₅H and the Pd(II) species formed after transmetalation between the Pd(II)X₂ complex and aryl-Bpin which forms a Pd-Ar_rich species. Thus a Pd(Ar_rich)(Ar_poor) complex is generated selectively which undergoes reductive elimination to generate the unsymmetrical biaryl product.

Disconnected nanotubular topography generated using electrochemical anodization in organic electrolytes demonstrates excellent mechanobactericidal effect, similar to nanopillars found on insect wings. The structures are mechanically robust and durable enough to sustain forces experienced in daily handling and can be generated even on complx 3D geometries, which commonly used top-down nanofabrication methods are incapable of.

Abstract

Bacterial contamination of implant surfaces is one of the primary causes of their failure, and this threat has been further exacerbated due to the emergence of drug-resistant bacteria. Nanostructured mechanobactericidal surfaces that neutralize bacteria via biophysical forces instead of traditional biochemical routes have emerged as a potential remedy against this issue. Here, we report on the bactericidal activity of titania nanotubes (TNTs) prepared by anodization, a well-established and scalable method. We investigate the differences in bacterial behavior between three different topographies and demonstrate the applicability of this technique on complex three-dimensional (3D) geometries. It was found that the metabolic activity of bacteria on such surfaces was lower, indicative of disturbed intracellular processes. The differences in deformations of the cell wall of Gram-negative and positive bacteria were investigated from electron micrographs Finally, nanoindentation experiments show that the nanotubular topography was durable enough against forces typically experienced in daily life and had minimal deformation under forces exerted by bacteria. Our observations highlight the potential of the anodization technique for fabricating mechanobactericidal surfaces for implants, devices, surgical instruments, and other surfaces in a healthcare setting in a cheap, scalable way.

Nanoscale transition metal oxides (TMO) is a promising contender for generating clean and sustainable hydrogen production from water with exceptional efficiency using water splitting approach. This review article specifically examines the use of TMO as active catalysts and current generator with this technique. It discusses the crucial component that governs the regulation of catalytic activity due to large active surface area of nanoscale TMO. The ultimate goal with the evolution of nanoscale TMO substrate is to produce a clean energy sources from environmental available water for future research to achieve the cost-effective, efficient, and environmentally friendly hydrogen production using water splitting approach.

Abstract

The development of green hydrogen generation technologies is increasingly crucial to meeting the growing energy demand for sustainable and environmentally acceptable resources. Many obstacles in the advancement of electrodes prevented water electrolysis, long thought to be an eco-friendly method of producing hydrogen gas with no carbon emissions, from coming to fruition. Because of their great electrical conductivity, maximum supporting capacity, ease of modification in valence states, durability in hard environments, and high redox characteristics, transition metal oxides (TMOs) have recently captured a lot of interest as potential cathodes and anodes. Electrochemical water splitting is the subject of this investigation, namely the role of transition metal oxides as both active and supportive sites. It has suggested various approaches for the logical development of electrode materials based on TMOs. These include adjusting the electronic state, altering the surface structure to control its resistance to air and water, improving the flow of energy and matter, and ensuring the stability of the electrocatalyst in challenging conditions. In this comprehensive review, it has been covered the latest findings in electrocatalysis of the Oxygen Evolution Reaction (OER) and Hydrogen Evaluation Reaction (HER), as well as some of the specific difficulties, opportunities, and current research prospects in this field.

Photothermal superhydrophobic coatings hold great promise in addressing the limitations of conventional superhydrophobic anti-icing coatings. However, developing such coatings with excellent impalement resistance, mechanical robustness and weather resistance remains a significant challenge. Here, we report facile preparation of robust photothermal superhydrophobic coatings with all the above advantages. The coatings were prepared by spraying a dispersion consisting of fluorinated silica nanoparticles, a silicone-modified polyester adhesive and photothermal carbon black nanoparticles onto Al alloy plates followed by thermal curing. Thermal curing caused migration of perfluorodecyl polysiloxane from within the coatings to the surface, effectively maintaining a low surface energy despite the presence of the adhesive. Therefore, combined with the hierarchical micro-/nanostructure, dense yet rough nanostructure, adhesion of the adhesive and chemically inert components, the coatings exhibited remarkable superhydrophobicity, impalement resistance, mechanical robustness and weather resistance. Furthermore, the coatings demonstrated excellent photothermal effect even in the -10 °C, 80% relative humidity and weak sunlight (0.2 sun) environment. Consequently, the coatings showed excellent passive anti-icing and active de-icing performance. Moreover, the coatings have good generalizability and scalability. We are confident that this study will accelerate the practical implementation of photothermal superhydrophobic coatings.