Abstract

Transition metal catalysts with modified second-coordination sphere employed in the electrocatalytic CO₂ can result in increased activity or directed product selectivity. Calixarenes can form metal complexes and potentially catalyze reactions within its cavity, taking advantage of the surrounding phenols groups to tune the reactivity by second-coordination sphere effects. Here, we present a Mn(I) bromotricarbonyl complex with phenanthroline-functionalized calix[8]arene ligands capable of electrocatalytically reducing CO₂ into different products with 2,2,2-trifluoroethanol as proton donor. The selectivity of the reaction seems to be affected by the calixarene cavity: two calixarene-free analogous complexes reduce CO₂ to CO almost exclusively, while the calixarene complexes produce primarily CO, H₂. Interestingly, in some cases the less frequently observed CH₄ was also detected, albeit with low Faradaic efficiency. Thus, the manganese center placed within the calixarene cavity promotes the formation of reduced CO₂ products by more than two electrons and two protons, affording CH₄ in some cases.

Abstract

Despite substantial advancements in thermal and photochemical catalysis, the evolution of similar processes within the realm of organic electrochemistry has seen a slower pace. However, recent years have heralded a remarkable surge in molecular electrocatalysis. This innovative technique harnesses the power of molecular catalysts to expedite electrochemical transformations. This article underscores the application of ferrocene (Fc) as a redox catalyst in organic electrosynthesis. It delves into the extensive utilization of Fc in organic electrosynthesis, particularly emphasizing its role in the electrocatalytic generation and reactions of heteroatom- and carbon-centered radicals, among various other reactions.

M.G. thanks the “China Scholarship Council” for the fellowship, and the authors are very grateful to the CNRS and Institut Polytechnique de Paris, which support this work.

Abstract

This mini review provides an overview of a range of Ni-, Co- and Pd-catalyzed electroreductive cross-coupling reactions. The combination of homogeneous transition-metal catalysis and electrochemistry are green alternatives to traditional reductive cross-coupling reactions to form Csp²-Csp², Csp²-Csp³ and some Csp³-Csp³ bonds in one step. Most of these reactions use the sacrificial anode process.

Abstract

Mass spectrometry (MS) is a central analytical technique used to study proteins and biomolecules. It measures mass-to-charge ratio of ions to identify and quantify molecules in simple and complex mixtures. Technological advancement in instrumentation, sample preparation methodologies, and data analysis workflows continue to push the capabilities of MS to answer more complicated questions and vice versa. Structural proteomics uses MS-based methodologies to characterize protein structure. Specifically, but not limited to, hydrogen deuterium exchange MS (HDX-MS) and crosslinking MS (XL-MS) are complementary techniques that capture the structural plasticity inherent to proteins in solution. This review is intended to present recent progress in HDX-MS and XL-MS that have allowed these techniques to be used not only for simple recombinant protein systems but with complex cellular systems.

Abstract

Calix[4]arenes and calix[4]resorcinarenes are well-known macrocyclic hosts that can be tailored to bind guests of very different natures, including anions, cations, and various neutral molecules. The molecular architectures of the hosts can be altered in many ways: by attaching polar or hydrophilic groups, extending inner cavities with enlarged aromatic side walls, and adding H-bonding sites to promote the formation of molecular capsules. The attachment of different types of redox-active moieties renders calix[4]arene and calix[4]resorcinarene derivatives electrochemically active, enabling them to either control the guest-binding properties of the receptors or be used as electrochemical sensors. This review will focus on calix[4]arene and calix[4]resorcinarene macrocyclic hosts with appended redox-active groups, such as ferrocene, tetrathiafulvalene, and quinone. We will discuss molecular receptors that can serve as redox sensors for cations or electron-deficient molecules or can bind and release their guests controlled by redox or electrochemical stimuli.

Abstract

Nickel-catalyzed cross-electrophile coupling (XEC) is an efficient method to form carbon-carbon bonds and has become an important tool for building complex molecules. While XEC has most often used stoichiometric metal reductants, these transformations can also be driven electrochemically. Electrochemical XEC (eXEC) is attractive because it can increase the greenness of XEC and this potential has resulted in numerous advances in recent years. The focus of this review is on electrochemical, Ni-catalyzed carbon-carbon bond forming reactions reported since 2010 and is categorized by the type of anodic half reaction: sacrificial anode, sacrificial reductant, and convergent paired electrolysis. The key developments are highlighted and the need for more scalable options is discussed.

Abstract

A novel metal- and oxidant-free electrooxidative selenylamination of o-aminophenacetylenes with diselenides for achieving 3-selenylindoles has been developed with moderate to excellent yield. The reaction proceeded smoothly with a broad substrate scope and highly functional group tolerance. The synthetic practicality of this innovative approach was demonstrated by its easy scalability. Moreover, mechanistic studies revealed that an in-situ generated selenium cation might be the key intermediate for the electrochemical selenocyclization process.

Abstract

An “OFF/ON” electric current switching protocol was developed as a new strategy for one-pot organic synthesis. Suzuki-Miyaura coupling of 2-bromopyridines with arylboronic acids in an electrochemical cell was performed without applying an electric current, and subsequently, the Pd-catalyzed electrochemical C−H bromination was conducted using the already-present Pd catalyst to obtain 2-(2-bromoaryl)pyridines as products. The one-pot synthesis of bromoarenes can also be achieved without adding an external Br source in the second step. Furthermore, an OFF/ON/OFF two-times switching protocol also realized the formation of an N-containing teraryl derivative.

Abstract

As an organic pseudocapacitive active material, 2, 3-Dichloro-1, 4-naphthoquinone (DNQ) was used in supercapacitors. Graphene with unique structures and high electrical conductivity acts as substrate. DNQ non-covalently modified graphene composite material (DNQ@rGO) was synthesized through the simple solvothermal synthesis. The redox reaction between naphthol and naphthoquinone occurs on reduced graphene oxide(rGO), which forms an ideal pseudocapacitance without destroying its sp ² network. The optimal DNQ@rGO electrode material obtained the specific capacitance of 361.2 Fg⁻¹ at 5 mV s⁻¹ in 1 mol L⁻¹ H₂SO₄ and exhibited excellent rate capability (capacitance retention of 87.5 % at 100 mV s⁻¹) in the three-electrode system. We also prepared holey layered oxygen-rich graphene hydrogels (HLGH) material, whose electrochemical performance is superior to traditional three-dimensional (3D) graphene hydrogels (GH). Finally, two asymmetric supercapacitors (ASCs) were assembled by using the DNQ@rGO (positive electrode), the HLGH and GH (negative electrode). The results show that the ASC with HLGH as negative electrode achieved the high energy and power densities due to the perfect matching of capacitance and kinetics between the positive and negative electrodes. The specific capacitance was almost no loss after 4700 cycles, showing the excellent stability.

Abstract

The functional roles of structured RNAs in the regulation of biological processes, and hence RNA's potential as an effective therapeutic target, have only recently been appreciated. Robust and high-throughput methods that identify potent RNA ligands are critical to the development of chemical probes and therapeutics. DNA-encoded libraries (DEL) technology has emerged as a powerful tool for protein ligand discovery, and its ability to generate large, custom-tailored, and novel chemical space offers unprecedented opportunities to discover the rules of RNA ligand design. In this review, we discuss the basic principles of DEL selection, current progress on the application of DEL to RNA targets, and the outlook of targeting RNA by DEL.