Monthly Archives: September 2023

Sustainable and selective transfer hydrogenation using waste shrimp shell‐based tetrazene‐Ru (II) para‐cymene catalyst with ethanol as a hydrogen source

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Sustainable and selective transfer hydrogenation using waste shrimp shell-based tetrazene-Ru (II) para-cymene catalyst with ethanol as a hydrogen source

An efficient ambient-temperature synthetic approach is presented for surface functionalization of waste shrimp shells using 3-(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DMPZ-Tz) via nucleophilic substitution with 3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (BDMPZ-Tz). The modified shrimp shells serve as a catalyst support for ruthenium-embedded transfer hydrogenation catalysts, employing ethanol as the hydrogen source and potassium carbonate as the base.


Sustainable chemical research emphasizes chitosan-based catalysts and the need to explore the direct utilization of waste shrimp shells, whereas the use of ethanol as a hydrogen source in transfer hydrogenation is less explored due to its unfavorable redox potential, higher energy barriers, generation of reactive intermediates, and catalyst poising via metal carbonyl species or decarbonylation. Herein, we disclosed an efficient synthetic approach, conducted at ambient temperature, for surface functionalization of waste shrimp shells with 3-(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (DMPZ-Tz) via nucleophilic substitution using 3,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazine (BDMPZ-Tz). This method results in a color change and a 75% increase in surface nitrogen content, eliminating the need for multiple syntheses and harsh reaction conditions. We utilized the strong coordination property between DMPZ-Tz and [Ru(p-cym)Cl2]2/RuCl3.3H2O to develop ruthenium-embedded transfer hydrogenation catalysts supported on shrimp shells. These catalysts were employed for the selective transfer hydrogenation of unsaturated carbonyl/aldehydes to saturated carbonyl/alcohols, utilizing ethanol as the hydrogen source and potassium carbonate as the base. The performance, selectivity, and reusability of the catalyst were thoroughly assessed through spectroscopic studies, in-situ monitoring of the reaction progress, initial rate kinetics, and control experiments. The obtained results strongly indicated that the anchoring of DMPZ-Tz played a crucial role in achieving superior performance compared with catalysts synthesized without it or utilizing its homogeneous counterparts. The catalyst exhibits efficient reactivity, selectivity, and broad substrate scope.

Bimetallic AuCo supported on magnetic crosslinked copoly(ionic liquid) nanohydrogel and study of its catalytic activity

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Bimetallic AuCo supported on magnetic crosslinked copoly(ionic liquid) nanohydrogel and study of its catalytic activity

AuCo bimetallic nanoparticles were supported on magnetic crosslinked copoly(ionic liquid) nanohydrogel and resulting material applied as an efficient recyclable catalyst in reduction reactions.


Synergistic effects in bimetallic catalysts produce a catalyst with superior activity than a monometallic component. In this work, a novel magnetic crosslinked copoly(ionic liquid) nanohydrogel was synthesized and employed for the stabilization of AuCo bimetallic nanoparticles (Fe3O4@PolyIL-AuCo). This material was characterized using different instrumental techniques such as FT-IR, TGA, XPS, VSM, solid-state UV–Vis, SEM mapping, and TEM. Results indicated a narrow size distribution of nanoparticles and high water dispersibility of Fe3O4@PolyIL-AuCo. Using this catalyst, a series of nitroarenes were reduced to the corresponding amines in aqueous media. In addition, organic dyes were efficiently degraded by this catalyst. Different experiments dealing with the same transformation confirmed that Fe3O4@PolyIL-AuCo exhibited higher catalytic activity than the similar monometallic Au and Co catalysts. This catalyst was recycled for at least 11 consecutive runs with very small deactivation, and TEM, VSM, and XPS confirmed the stability of the reused catalyst.

Efficient Solution Phase Synthesis of PPII Helix Mimicking Ena/VASP EVH1 Inhibitors from Proline‐Derived Modules (ProMs)

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Efficient Solution Phase Synthesis of PPII Helix Mimicking Ena/VASP EVH1 Inhibitors from Proline-Derived Modules (ProMs)

In search of EVH1 domain inhibitors as potential anti-metastasis drugs, we have developed an efficient and scalable liquid-phase synthesis of pseudo-peptidic ligands composed of conformationally defined proline-derived modules (ProMs).


Abstract

In the search for efficient inhibitors for the enabled/vasodilator-stimulated phosphoprotein homology 1 (EVH1) domain to reduce cell motility in metastatic cancer, we previously developed a toolkit of proline-derived modules (ProMs), which mimic the PPII helix found in the natural −FPPPP− binding motif of EVH1. In this work, we describe the modular assembly of these ProM-based pentapeptidic EVH1 ligands through liquid phase peptide synthesis. We initially used pentafluorophenyl (Pfp) active esters for amide bond formation and built up the growing peptide chain from the C- to the N-terminus. Switching to HATU/DIPEA coupling conditions and changing the directionality of the synthesis from the N- to the C-terminus afforded the target ligands with improved overall yields and purity. Employing a Fmoc-protected (instead of the N-acetylated) phenylalanine derivative as N-terminal building block significantly reduced epimerization. In contrast to the originally used solid phase peptide synthesis (SPPS), the developed solution phase method allowed for a facile alteration of the C-terminal ProM unit and the production of various pentapeptidic ligands in an efficient fashion even on a multigram scale.

Characterization and Comparative Study of Energy Efficient Mechanochemically Induced NASICON Sodium Solid Electrolyte Synthesis

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In recent years, there is growing interest in solid-state electrolytes due to their many promising properties, making them key to the future of battery technology. This future depends among other things on easy processing technologies for the solid electrolyte. The sodium superionic conductor (NASICON) Na3Zr2Si2PO12 is a promising sodium solid electrolyte; however, reported methods of synthesis are time and energy consuming. To this effect, attempt was made to develop a simple time efficient alternative processing route. Firstly, a comparative study between a new method and commonly reported methods was carried out to gain a clear insight into the mechanism of formation of sodium superionic conductors (NASICON). It was observed that through a careful selection of precursors, and the use of high-energy milling (HEM) the NASICON conversion process was enhanced and optimized, this reduces the processing time and required energy, and opens up a new alternative route for synthesis. The obtained solid electrolyte was stable during Na cycling vs. Na-metal at 1mA/cm2, and a room temperature conductivity of 1.8 mS/cm was attained.

Sodium‐Selenium Batteries with Outstanding Rate Capability by Introducing Cubic Mn2O3 Electrocatalyst

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With their high volumetric capacity and electronic conductivity, sodium-selenium (Na-Se) batteries have attracted attention for advanced battery systems. However, the irreversible deposition of sodium selenide (Na2Se) results in rapid capacity degradation and poor Coulombic efficiency. To address these issues, cubic α-Mn2O3 is introduced herein as an electrocatalyst to effectively catalyze Na2Se conversion and improve the utilization of active materials. The results show that the addition of 10 wt% Mn2O3 in the Se/KB composite enhances the conversion from Na2Se to Se by lowering activation energy barrier and leads to fast sodium-ion kinetics and low internal resistance. Consequently, the Mn2O3-based composite delivers a high specific capacity of 635 mAh·g-1 at 675 mA·g-1 after 250 cycles as well as excellent cycling stability for 800 cycles with a high specific capacity of 317 mAh·g-1 even at the high current density of 3375 mA·g-1. Due to the cubic Mn2O3 electrocatalyst, the performance of the composites is mostly superior to existing state-of-the-art Na-Se batteries reported in the literature.

Combining Ligand Deuteration with Ligand Bulkiness in Non‐Heme Iron Oxidation Catalysis: Enhancing Catalyst Lifetime and Site‐Selectivity

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Bulky tri-isopropyl silyl (TIPS) substituents and deuterium atoms in the ligand design have been shown to enhance the site-selective oxidation of aliphatic C−H bonds and the epoxidation of C=C bonds in non-heme iron oxidation catalysis. In this work, a series of non-heme iron complexes were developed by combining TIPS groups and deuterium atoms in the ligand. These bulky deuterated complexes show a significant increase in catalytic performance. A broad range of substrates was oxidized with excellent yields, particularly, using [Fe(OTf)2((S,S)-TIPSBPBP-D4)] (1-TIPS-D4) via a fast or slow oxidant addition protocol, resulting in an overall improvement in catalytic performance. Notably, in the oxidation of the complex substrate trans-androsterone acetate, the use of a slow addition protocol and a lower catalyst loading of 1-TIPS-D4 resulted in significant increases in reaction efficiency. In addition, kinetic and catalytic studies showed that deuteration does not affect the catalytic activity and the secondary C-H site-selectivity but increased the catalysts’ lifetime resulting in higher conversion/yield. Accordingly, the yield of selectively oxidized secondary C-H products also increases with the overall yield by using the bulky deuterated iron complexes as catalysts. These catalytic improvements of the bulky deuterated complexes exemplify the enhanced design of ligands for homogeneous oxidation catalysis.

Visible‐Light‐Promoted Palladium‐Catalyzed Cross‐Coupling of Iodocarboranes with Disulfides and Phenylselenyl Chloride

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Comprehensive Summary

This work describes a general method for the synthesis of a series of sulfenylated and selenylated carboranes at room temperature using readily available iodocarboranes as starting materials via boron-centered carboranyl radicals. Such hypervalent boron radicals are generated by a visible-light-promoted Pd(0)/Pd(I) pathway. They are useful intermediates and can be trapped by disulfides and phenylselenyl chloride for the convenient construction of B-S/Se bonds.

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Aptamer‐based antibiotic electrochemical detection platform using portable plastic gold electrode and multichannel chip

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Abstract

The development of accurate, rapid and practical electrochemical sensing technology for antibiotic detection has an important application prospect in many fields such as food safety, environmental monitoring, medical and health care. In this research, kanamycin specific nucleic acid aptamer and its partially complementary short chain were self-assembled onto the surface of an integrated portable plastic gold electrode (PGE) by Au-S bond, and a simple kanamycin electrochemical biosensor interface was constructed. At the same time, the epoxy resin channel layer was designed, and the auxiliary instrument was set up independently in the laboratory, which could help to measure and analyze eight groups of samples automatically in turn. The quantitative analysis results showed that in 20 minutes, the sensor had a good linear relationship between the peak current change of square wave voltammetry and the negative logarithm of kanamycin concentration when kanamycin concentration was in the range of 1-1000 μM, and the detection limit could reach 0.40 μM. In addition, the discrimination could be achieved within 5 minutes in the real-time analysis mode. The sensor had a simple construction method, good selectivity and stability, and could be used for rapid or real-time detection of kanamycin residues in actual water samples, which provided a new direction for the practical detection of kanamycin in environmental water samples.

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Interface charge distribution engineering of Pd‐CeO2/C for efficient carbohydrazide oxidation reaction

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Carbohydrazide electrooxidation reaction (COR) is a potential alternative to oxygen evolution reaction in water splitting process. However, the sluggish kinetics process impels to develop efficient catalysts with the aim of the widespread use of such catalytic system. Since COR concerns the adsorption/desorption of reactive species on catalysts, the electronic structure of electrocatalyst can affect the catalytic activity. Interface charge distribution engineering can be considered to be an efficient strategy for improving catalytic performance, which facilitates the cleavage of chemical bond. Herein, highly dispersed Pd nanoparticles on CeO2/C catalyst are prepared and the COR catalytic performance is investigated. The self-driven charge transfer between Pd and CeO2 can form the local nucleophilic and electrophilic region, promoting to the adsorption of electron-withdrawing and electron-donating group in carbohydrazide molecule, which facilitates the cleavage of C-N bond and the carbohydrazide oxidation. Due to the local charge distribution, the Pd-CeO2/C exhibits superior COR catalytic activity with a potential of 0.27 V to attain 10 mA cm-2. When this catalyst is used for energy-efficient electrolytic hydrogen production, the carbohydrazide electrolysis configuration exhibits a low cell voltage (0.6 V at 10 mA cm-2). This interface charge distribution engineering can provide a novel strategy for improving COR catalytic activity.

Fully Conjugated Covalent Organic Frameworks: Synthesis, Structures and Applications

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Fully Conjugated Covalent Organic Frameworks: Synthesis, Structures and Applications†


Comprehensive Summary

This review presents a comprehensive examination of fully conjugated covalent organic frameworks (COFs), which constitute an emerging class of porous materials with immense potential for diverse applications. This article focuses on diversified fully conjugated COFs, including sp2 carbon-carbon linkages, pyrazine linkages, benzobisoxazole linkages, dioxin linkages, β-aminoalkenone linkages, etc. The synthesis techniques and structural attributes of these COFs are expounded upon in great detail, along with their potential applications in various fields. The review thus provides a valuable resource for researchers keen on delving into the synthesis and applications of fully conjugated COFs, thereby highlighting their potential for developing novel functional materials with distinctive properties.