We report herein a mild stereo- and regioselective dearomatization of quinolines using the simple low valent HCo(N2)(PPh3)3 complex that exhibits labile ligands. Conditions to form selectively, at room temperature, high-valued 1,4-bis-borylated tetrahydroquinolines from simple starting heteroaromatic compounds have been developed. The efficient and selective functionalization of a large scope of quinolines bearing various electron-donating or electron-withdrawing substituents is presented, as well as the post-modification of the resulting C–B bond. NMR and labelling studies are consistent with a cascade mechanism pathway, starting from an in situ generated paramagnetic bis-quinoline cobalt(I) hydride complex. A first quinoline dearomatization followed by a cobalt(I)-catalyzed Markovnikov hydroboration of the remaining double bond allows the introduction of the boronic ester group only at C4 position. DFT calculations particularly highlight the importance of the cobalt triplet state throughout the reaction pathway, and bring some rationalization for the observed C4 selective borylation.
Analytical Tools for Dynamic Combinatorial Libraries of Cyclic Peptides
Target-directed dynamic combinatorial chemistry is a very attractive strategy for the discovery of bioactive peptides. However, its application has not yet been demonstrated, presumably due to analytical challenges that arise from the diversity of a peptide library with combinatorial side-chains. We previously reported an efficient method to generate, under biocompatible conditions, large dynamic libraries of cyclic peptides grafted with amino acid’s side-chains, by thiol-to-thioester exchanges. In this work, we present analytical tools to easily characterize such libraries by HPLC and mass spectrometry, and in particular to simplify the isomers’ distinction requiring sequencing by MS/MS fragmentations. After structural optimization, the cyclic scaffold exhibits a UV-tag, absorbing at 415 nm, and an ornithine residue which favors the regioselective ring-opening and simultaneous MS/MS fragmentation, in the gas-phase, upon CID activation.
[ASAP] Small Plasma Membrane-Targeted Fluorescent Dye for Long-Time Imaging and Protein Degradation Analyses
Analytical Chemistry
DOI: 10.1021/acs.analchem.3c01980
Synthesis of Highly Functionalized Spirocycles, and Pentafulvene Containing Dyes Involving 2‐(2’‐ketoalkyl)‐1,3‐indandiones
Synthesis of highly functionalized spiro[4.4]nonane, and spiro[4.5]decane motifs by the reaction of dimethylacetylenedicarboxylate (DMAD) with 2-(2'-ketoalkyl)-1,3-indandiones, 2-(3'-ketoalkyl)-1,3-indandiones, respectively, has been developed by utilizing a catalytic amount of DABCO. The tertiary hydroxy-containing spiro[4.4]nonane products were converted into fully conjugated pentafulvene π-systems in an acidic medium via dehydration and unprecedented C-C bond rearrangement.
Pairing Electrocarboxylation of Unsaturated Bonds with Oxidative Transformation of Alcohol and Amine
Paired electrolysis: Coupling electrocarboxylation, incorporating CO2 into ketone, imine, and alkene, with alcohol oxidation or oxidative cyanation of amine provides an efficient access to carboxylic acids as well as aldehyde/ketone or α-nitrile amine at the cathode and anode respectively in a divided cell.
Abstract
A parallel paired electrosynthetic method, coupling electrocarboxylation incorporating CO2 into ketone, imine, and alkene with alcohol oxidation or oxidative cyanation of amine, was developed for the first time. Various carboxylic acids as well as aldehyde/ketone or α-nitrile amine were prepared at the cathode and anode respectively in a divided cell. Its utility and merits on simultaneously achieving high atom-economic CO2 utilization, elevated faradaic efficiency (FE, total FE of up to 166 %), and broad substrate scope were demonstrated. The preparation of pharmaceutical intermediates for Naproxen and Ibuprofen via this approach proved its potential application in green organic electrosynthesis.
Sustainable Polyvinyl Chloride‐Derived Soft Carbon Anodes for Potassium‐Ion Storage: Electrochemical Behaviors and Mechanism
One stone kills two birds: Sustainable polyvinyl chloride-derived soft carbon anodes were developed for potassium-ion batteries. The microstructure and electrochemical performances of this soft carbon could be tuned by altering the carbonization temperatures. Adsorption-intercalation mechanism is verified by in situ Raman spectroscopy.
Abstract
Soft carbon is a promising anode material for potassium-ion batteries due to its favorable properties such as low cost, high conductivity, stable capacity, and low potential platform. Polyvinyl chloride, as a white pollutant, is a soft carbon precursor that can be carbonized at varying temperatures to produce soft carbons with controllable defect and crystal structures. This work investigates the effect of carbonization temperature on the crystalline structures of the obtained soft carbons. In situ Raman spectroscopy was used to elucidate the adsorption-intercalation charge storage mechanism of potassium ions in soft carbons. Soft carbons prepared at the temperature of 800 °C have a defect-rich, short-range ordered structure, which provides optimal intercalation and adsorption sites for potassium ions, resulting in a satisfactory capacity of 302 mAh g−1. This work presents new possibilities for designing soft carbon materials from recycling plastics for potassium-ion batteries.
Biobased Silicon and Biobased Silica: Two Production Routes Whose Time has Come
An updated bioeconomy perspective on biobased green chemistry routes to high-purity silicon and silica in the context of societal, economic and environmental trends reshaping chemical productions is presented.
Abstract
This study offers an updated bioeconomy perspective on biobased routes to high-purity silicon and silica in the context of the societal, economic and environmental trends reshaping chemical processes. We summarize the main aspects of the green chemistry technologies capable of transforming current production methods. Coincidentally, we discuss selected industrial and economic aspects. Finally, we offer perspectives of how said technologies could/will reshape current chemical and energy production.
Interplay Between Particle Size and Hierarchy of Zeolite ZSM‐5 During the CO2‐to‐aromatics Process
Aromatics derived from non-fossil feedstock are essential for a sustainable society. This work investigates the impact of particle size and hierarchy of the zeolite ZSM-5 to yield aromatics during CO2 hydrogenation over bifunctional (Fe@K/H-ZSM-5) catalytic systems.
Abstract
The CO2-to-aromatics process is a chemical reaction that converts carbon dioxide (CO2) into valuable petrochemical, i. e., aromatics (especially, benzene, toluene, and xylene) over the metal/zeolite bifunctional catalytic systems. These aromatics are used in producing plastics, fibers, and other industrial products, which are currently exclusively sourced from fossil-derived feedstocks. The significance of this process lies in its potential to mitigate climate change by reducing greenhouse gas emissions and simultaneously producing valuable chemicals. Consequently, these CO2-derived aromatics can reduce the reliance on fossil fuels as a source of feedstocks, which can help to promote a more sustainable and circular economy. Owing to the existence of a wider straight channel favoring the aromatization process, zeolite ZSM-5 is extensively used to yield aromatics during CO2 hydrogenation over bifunctional (metal/zeolite) catalytic systems. To provide a better understanding of this unique property of zeolite ZSM-5, this work investigates the impact of particle size and hierarchy of the zeolite and how these govern the reaction performance and the overall selectivity. As a result, an improved understanding of the zeolite-catalyzed hydrocarbon conversion process has been obtained.
Front Cover: Co3O4 Supported on β‐Mo2C with Different Interfaces for Electrocatalytic Oxygen Evolution Reaction (ChemSusChem 19/2023)
The Front Cover shows that a suitably regulated interface between Co3O4 and β-Mo2C can boost the electrocatalytic performance of water oxidation. The β-Mo2C support in the Co3O4@β-Mo2C composite has the capability to activate water molecules. By comparing three Co3O4@β-Mo2C composites with different interfaces, it has been shown that the compact interface from β-Mo2C nanobelt support enhanced the conductivity of the composite and regulated the interfacial electron redistribution to promote the electrocatalysis. More information can be found in the Research Article by J. Zhang et al.
Integration of Cobalt Phthalocyanine, Acetylene Black and Cu2O Nanocubes for Efficient Electroreduction of CO2 to C2H4
A tandem catalyst, Cu2O NCs-C-Copc, consisting of acetylene black, cobalt phthalocyanine (Copc) and Cu2O nanocubes was developed for efficient converting of CO2 to C2H4. We propose the Cu2O NCs-C-Copc mechanism suppressing side reactions and simultaneously enriching CO. Here, we report faradaic efficiencies of C2H4 formation of up to 58.42 % at −1.1 V vs. RHE in 0.1 M KHCO3 and 70.31 % at −0.76 V vs. RHE in 1.0 M KOH.
Abstract
Suppressing side reactions and simultaneously enriching key intermediates during CO2 reduction reaction (CO2RR) has been a challenge. Here, we propose a tandem catalyst (Cu2O NCs-C-Copc) consisting of acetylene black, cobalt phthalocyanine (Copc) and cuprous oxide nanocubes (Cu2O NCs) for efficient CO2-to-ethylene conversion. Density-functional theory (DFT) calculation combined with experimental verification demonstrated that Copc can provide abundant CO to nearby copper sites while acetylene black successfully reduces the formation energies of key intermediates, leading to enhanced C2H4 selectivity. X-ray photoelectron spectroscopy (XPS) and potentiostatic tests indicated that the catalytic stability of Cu2O NCs-C-Copc was significantly enhanced compared with Cu2O NCs. Finally, the industrial application prospect of the catalyst was evaluated using gas diffusion electrolyzers. The of Cu2O NCs-C-Copc can reach to 58.4 % at −1.1 V vs. RHE in 0.1 M KHCO3 and 70.3 % at −0.76 V vs. RHE in 1.0 M KOH. This study sheds new light on the design and development of highly efficient CO2RR tandem catalytic systems.