Crystalline-Amorphous Interfaces Engineering of CoO-InOx for Highly Efficient CO2 Electroreduction to CO.

As a fundamental product of CO2 conversion through two-electron transfer, CO is used to produce numerous chemicals and fuels with high efficiency, which has broad application prospects. In this work, it has successfully optimized catalytic activity by fabricating an electrocatalyst featuring crystalline-amorphous CoO-InOx interfaces, thereby significantly expediting CO production. The 1.21%CoO-InOx consists of randomly dispersed CoO crystalline particles among amorphous InOx nanoribbons. In contrast to the same-phase structure, the unique CoO-InOx heterostructure provides plentiful reactive crystalline-amorphous interfacial sites. The Faradaic efficiency of CO (FECO) can reach up to 95.67% with a current density of 61.72 mA cm-2 in a typical H-cell using MeCN containing 0.5 M 1-Butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF6) as the electrolyte. Comprehensive experiments indicate that CoO-InOx interfaces with optimization of charge transfer enhance the double-layer capacitance and CO2 adsorption capacity. Theoretical calculations further reveal that the regulating of the electronic structure at interfacial sites not only optimizes the Gibbs free energy of *COOH intermediate formation but also inhibits HER, resulting in high selectivity toward CO.

Unveiling PET Hydrolase Surface Dynamics through Fluorescence Microscopy.

PET hydrolases are an emerging class of enzymes that are being heavily researched for their use in bioprocessing polyethylene terephthalate (PET). While work has been done in studying the binding of PET oligomers to the active site of these enzymes, the dynamics of PET hydrolases binding to a bulk PET surface is an unexplored area. Here, methods were developed for total internal reflection fluorescence (TIRF) microscopy and fluorescence recovery after photobleaching (FRAP) microscopy to study the adsorption and desorption dynamics of these proteins onto a PET surface. TIRF microscopy was employed to measure both on and off rates of two of the most commonly studied PET hydrolases, PHL7 and LCC, on a PET surface. It was found that these proteins have a much slower off rates on the order of 10-3  s-1 , comparable to non-productive binding in enzymes such as cellulose. In combination with FRAP microscopy, a dynamic model is proposed in which adsorption and desorption dominates over lateral diffusion over the surface. The results of this study could have implications for the future engineering of PET hydrolases, either to target them to a PET surface or to modulate interaction with their substrate.

Identification, characterization and application of M16AT, a new organic solvent-tolerant (R)-enantio-selective type IV amine transaminase from Mycobacterium sp. ACS1612.

Biocatalysis has emerged as a powerful alternative to traditional chemical methods, especially for asymmetric synthesis. As biocatalysts usually exhibit excellent chemical, regio- and enantioselectivity, they facilitate and simplify many chemical processes for the production of a broad range of products. Here, a new biocatalyst called, R-selective amine transaminases (R-ATAs), was obtained from Mycobacterium sp. ACS1612 (M16AT) using in-silico prediction combined with a genome and protein database. A two-step simple purification process could yield a high concentration of pure enzyme, suggesting that industrial application would be inexpensive. Additionally, the newly identified and characterized R-ATAs displayed a broad substrate spectrum and strong tolerance to organic solvents. Moreover, the synthetic applicability of M16AT has been demonstrated by the asymmetric synthesis of (R)-fendiline from of (R)-1-phenylethan-1-amine.

Supporting Electrolyte-Free Electrochemical Oxidative C-H Sulfonylation and Thiocyanation of Fused Pyrimidin-4-Ones in an All-Green Electrolytic System.

An electrooxidative C-H functionalization is a widely accepted route to obtain sulfur-containing arenes and heteroarenes. However, this process often involves using non-recyclable supporting electrolytes, (co)solvents like hexafluoroisopropanol, additives like acid, or catalysts. The use of additional reagents can increase costs and waste, reducing atom efficiency. Moreover, unlike other nitrogen-containing heterocycles, there have only been sporadic reports of electrochemical C-H functionalization in fused pyrimidin-4-ones, and an electrolyte-free process has yet to be developed. This work demonstrates that such anodic coupling reactions can be performed in an all-green electrolytic system without using such additional electrolytes or HFIP, maintaining a high atom economy. This C-H functionalization strategy utilizes inexpensive sodium sulfinates and ammonium thiocyanate as sulfonylating and thiocyanating agents in an undivided cell at a constant current, using a mixture of CH3 CN/H2 O as solvent at room temperature. Thus, fused pyrimidin-4-ones can be selectively converted into C3-sulfonylated and -thiocyanated derivatives in moderate to good yields.

Replacement of Toxic Hydrazines in Satellite Propulsion with Greener Dinitramide-Based Energetic Ionic Liquid Candidates.

Satellite propulsion uses liquid mono or bi-propellants composed of a hydrazine in combination with a strong oxidant. However, hydrazines are highly toxic. As a result, many research efforts for more environmentally compatible propellants have been made over the past decade. In this study we evidence green formulations that retain high propulsive performances. They are based on the dinitramide anion. From an initial library of 37 ammonium dinitramides 3 best candidates were selected after evaluation of their potential syntheses, calculated theoretical performances, experimental synthesis optimizations and decomposition temperatures. These three salts were then formulated to obtain acceptable sensitivities and melting points, which eventually led to only one formulation being retained: a 40 : 60 mixture of dimethylammonium dinitramide and ammonium dinitramide phlegmatized by 10 % of glycerol.

Green Late-Stage Functionalization of Tryptamines.

An efficient and rapid protocol for the oxidative halogenation of tryptamines with 10 % aqueous NaClO has been developed. This reaction is featured by its operational simplicity, metal-free conditions, no purification, and high yield. Notably, the resulting key intermediates are suitable for further functionalization with various nucleophiles, including amines, N-aromatic heterocycles, indoles and phenols. The overall transformation exhibits broad functional-group tolerance and is applicable to the late-stage functionalization of complex biorelevant molecules.

A Computational Study of Reactions with Boric Acid Aimed to Promote the Utilization of Lignin.

For exploring the reaction between the hydroxyl groups of lignin and boric acid under the alkaline condition, we study three proposed mechanisms for the formation of the anionic borate diester (ABDE) using the salicyl alcohol anion as the model compound by the density functional theory. ABDE has high flame retardancy and is a potentially practical application of lignin. The catalysis of sodium cation is found to enhance the deprotonation of the water cluster. The deprotonated product, hydroxide anion, is essential to the critical step, which is the cleavage of B-O bonds of the boric acid molecule, in reaction mechanisms. The energy profiles of the mechanisms show that the reaction between lignin and boric acid may start from the hydroxymethyl moieties of lignin since it requires less energy for the aforementioned critical step than from the phenol moieties of lignin. Moreover, the hydroxide anions compete with the hydroxymethyl groups in lignin for the formation of B-O bonds by forming tetrahydroxyborate anion (TBA) which requires very high activation energies to further react to the desired product ABDE. The optimal condition is to enhance the catalytic effect of sodium cations and meanwhile to control the formation of TBA.

Oxidation of Alcohols in Continuous Flow with a Solid Phase Hypervalent Iodine Catalyst.

One of the most useful transformations in the synthetic chemist arsenal is the oxidation of alcohols to their corresponding carbonyl congeners. Despite its seemingly straightforward nature, this transformative reaction predominantly relies on the use of metals or hazardous reagents, making these processes highly unsustainable. To address this challenge, we have developed a sustainable metal-free method for the oxidation of alcohols in continuous flow. Using a solid phase hypervalent iodine catalyst and nBu4HSO5 as a phase transfer catalyst and co-oxidant, primary and secondary alcohols were selectively oxidized to the corresponding carbonyl motifs. This operationally simple continuous-flow set-up is highly robust (15 cycles run without significant catalyst leaching or loss of reaction efficiency), uses green solvents, such as acetonitrile or acetic acid, and is readily scalable.

Electrochemical Dehydration of Dicarboxylic Acids to Their Cyclic Anhydrides.

An intramolecular electrochemical dehydration reaction of dicarboxylic acids to their cyclic anhydrides is presented. This electrolysis allows dicarboxylic acids as naturally abundant, inexpensive, safe, and readily available starting materials to be transformed into carboxylic anhydrides under mild reaction conditions. No conventional dehydration reagent is required. The obtained cyclic anhydrides are highly valuable reagents in organic synthesis, and in this report, we use them in-situ for acylation reactions of amines to synthesize amides. This work is part of the recent progress in electrochemical dehydration, which - in contrast to electrochemical dehydrogenative reactions for example - is an underexplored field of research. The reaction mechanism was investigated by 18O isotope labeling, revealing the formation of sulfate by electrochemical oxidation and hydrolysis of the thiocyanate-supporting electrolyte. This transformation is not a classical Kolbe electrolysis, because it is non-decarboxylative, and all carbon atoms of the carboxylic acid starting material are contained in the carboxylic anhydride. In total, 20 examples are shown with NMR yields up to 71 %.

Sniffing Out the Sustainable Future: The Renewability Revolution in Fragrance Chemistry.

In this review, the impact of the transition from today's resource-wasting petrochemical economy towards a 100/100 renewable and biodegradable future is discussed with respect to the fragrance families: "citrus", "green", "fruity", "floral", "floriental", "oriental", "woody", "chypre" and "fougère". After benchmark data on ingredients usage, definitions on biodegradation and sustainability are given. Celebrating the 150th anniversary of synthetic vanillin, its historic synthesis from renewable starting materials serves as introduction. In the grand scheme of things, citrus scents upcycled from the beverages industry, are already an ideal case for 100/100 with new opportunities for artificial essential oils. In the fruity domain, transparent and lactonic ingredients are available in a sustainable manner. However, in the domain of green odorants, there is a lack of green chemistry for important key materials. In the floral family, renewability is more critical than biodegradability, but cost is an issue. Thanks to Ambrox and maltol, florientals and orientals will persist, while woody notes severely lack an Iso E Super replacer. In the chypre genre, patchouli became the new moss, but more musks are increasingly in demand. With their high percentage of linalool and dihydromyrcenol, the construction of fougères could well become a precedent for other families, despite challenges in vetiver and salicylates. Still, the challenges exemplified here create immense opportunities for new perfumery materials.

Wittig Reaction in Deep Eutectic Solvents: Expanding the DES Toolbox in Synthesis.

Wittig reaction between substituted phosphonium salts and (hetero)aromatic and alkyl carbonyl compounds in Deep Eutectic Solvents has been developed under a scalable and friendly protocol. Highly efficient reactions were successfully run with a wide range of bases including organic (DBU, LiTMP, t-BuOK) and inorganic (NaOH, K2CO3) ones in ChCl/Gly 1 : 2 (mol/mol) as solvent under mild conditions, at room temperature and under air. The proposed protocol was applied to a wide range of substrates, including (hetero)aromatic aldehydes with substituents as halogens (I, Br, Cl), EDG (alkoxy, methyl), EWG (NO2, CF3) or reactive groups as CN, esters, and ketones. Vinylic, alkynyl and cycloalkyl, alicyclic and α,ß-unsaturated aldehydes can also be used. Highly electrophilic ketones gave good yields. The diastereoselectivity of the reaction is in complete agreement with the E/Z ratio predictable under traditional conditions. We demonstrated that the protocol is scalable to 2 g (5 mmol) of phosphonium salt, furthermore the proposed workup protocol allows to remove TPPO without need of additional chromatographic purification.

Mimicking Ozonolysis via Mechanochemistry: Internal Alkynes to 1,2-Diketones using H5IO6.

Utilizing periodic acid as an environmentally benign oxidizing agent, this study introduces a novel mechanochemical method that mimics ozonolysis to convert internal alkynes into 1,2-diketones, showcasing effective emulation of ozone's reactivity. Notably, this oxidation occurs at room temperature in aerobic conditions, eliminating the need for toxic transition metals, hazardous oxidants, or expensive solvents. Through control experiments validating the mechanism, substantial evidence supports a concerted reaction pathway. This progress marks a significant stride toward cleaner and more efficient chemical synthesis, mitigating the environmental impact of conventional processes. Assessing the green chemistry metrics in both solvent-free and previously reported solvent-based methods, our eco-friendly protocol demonstrates an E-factor of 7.40, a 51.7 % atom economy, a 45.5 % atom efficiency, 100 % carbon efficiency, and 11.9 % reaction mass efficiency when solvents are not used.

Green Synthesis of the Triazine Derivatives and their Application for the Benign Electrocatalytic Reaction of Nitrate Reduction to Ammonia.

This work uses green sustainable reactions twice. Firstly, it is microwave synthesis: 2,4,6-tribiphenyl-4-yl-1,3,5-triazine and similar compounds were prepared in a closed microwave reactor in n-octane by the Friedel-Crafts reaction. Second, a hybrid electrocatalyst for the highly demanded electrochemical reaction of nitrate reduction to ammonia (NO3RR) was prepared based on this material. This reaction has great potential to replace the energy-intensive Haber-Bosch process, and in addition, has independent value for the elimination of nitrate contamination of water resources. As shown in the work, microwave synthesis is an eco-friendly method for the synthesis of complex organic compounds; fast, selective and with a high yield of the target product. The electrocatalyst deposited on the graphite electrode consisted of a layer of 2,4,6-tribiphenyl-4-yl-1,3,5-triazine and related compounds coated with cobalt oxide. The hybrid catalyst was firmly retained on the graphite electrode during NO3RR and the material showed impressive stability with almost no decrease in catalytic activity even after the fifth cycle. Both 2,4,6-tribiphenyl-4-yl-1,3,5-triazine and the catalyst based on this substance were characterized by SEM, XPS, XRD, UV-vis spectra, cyclic (and linear) voltammetry, and chronoamperometry. This work can serve as a starting point for the development of stable and durable electrocatalysts for NO3RR using triazine derivatives.

The Strategies towards Electrochemical Generation of Aryl Radicals.

The advancement in electrochemical techniques has unlocked a new path for achieving unprecedented oxidations and reductions of aryl radical precursors in a controlled and selective manner. This approach facilitates the construction of aromatic carbon-carbon and carbon-heteroatom bonds. In light of the green merits and the growing importance of this technique in aryl radical chemistry, this review aims to provide an overview of the recent advance in the electrochemical generation of aryl radicals organized by the aryl radical precursor type, with a focus on the substrate scope, limitation, and underlying mechanism, thereby inspiring future work on electrochemical aryl radical generation.

Onset of Nitriles Hydration with an Environmentally Benign Catalyst: in-Water versus on-Water Conditions.

The reaction yield of nitriles hydration using a catalyst depends on the aqueous medium. Using ab initio molecular dynamics, we probed whether "in-water" (in bulk medium) or "on-water" (at the interface with vacuum) conditions can change the onset of the reaction. Investigating a hydrogen-bond mediated mechanism, the lifetimes of the intermolecular interaction between benzonitrile and choline in the two protocols were compared, and the diffusion of the hydroxide anion around the cyano group was discussed.

Greener Approach Towards Synthesis of Palladium-Decorated Graphene Derivatives for Hydrogen Adsorption.

A simple, green, and relatively fast procedure was used to prepare palladium decorated graphene-based materials. A parent graphene-like material with a high specific surface area of up to 384 m2 /g and a total pore volume of 0.42 cm3 /g was prepared via a fast, solvent-free ball milling of graphite powder only. Post-synthetic modification of this graphene-like material was performed via a simplified method using palladium chloride and a small amount of a non-harsh reducing agent - formic acid. Palladium decoration (2.1 wt%) allowed obtaining a few times higher hydrogen adsorption (0.42 wt% at 30 °C and 40 bar) compared to that on bare graphene-based materials. Palladium-decorated graphene materials are promising for hydrogen storage and their usage in this application represents an alternative for conventional fossil fuels. The proposed synthesis and post-modification strategies are in line with green synthesis strategies.

Dihydroazolopyrimidines: Past, Present and Perspectives in Synthesis, Green Chemistry and Drug Discovery.

Dihydroazolopyrimidines are an important class of heterocycles that are isosteric to natural purines and are therefore of great interest primarily as drug-like molecules. In contrast to the heteroaromatic analogs, synthetic approaches to these compounds were developed much later, and their chemical properties and biological activity have not been studied in detail until recently. In the review, different ways to build dihydroazolopyrimidine systems from different building blocks are described - via the initial formation of a partially hydrogenated pyrimidine ring or an azole ring, as well as a one-pot assembly of azole and azine fragments. Special attention is given to modern approaches: multicomponent reactions, green chemistry, and the use of non-classical activation methods. Information on the chemical properties of dihydroazolopyrimidines and the prospects for their use in the design of drugs of various profiles are also summarized in this review.