First‐Principles Study of Carbon‐Substituted ZnO Monolayer for Adjusting Lithium Adsorption in Battery Application

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First-Principles Study of Carbon-Substituted ZnO Monolayer for Adjusting Lithium Adsorption in Battery Application

We investigate the structural stability, local density of states, bonding information, and charge distribution differences of C-substituted ZnO (C/VZnxOy ) monolayer structures, as well as their interactions with lithium atoms, using the density functional theory (DFT) method. The results indicate that all C/VZnxOy structures are stable. They bind as well as turn Li3 to Li3 + with varying binding strengths.


Abstract

Structural stability, local density of states, bonding information, and charge distribution differences of C-substituted ZnO (C/VZnxOy ) monolayer structures, as well as their interactions with lithium atoms, are investigated using the density functional theory (DFT) method. The energy required to generate vacancies in pristine ZnO monolayers is considerably high, but since the C atoms are strongly adsorbed in the vacant sites, the energy required to form C/VZnxOy structures is reduced. These lattice substitutions cause an alteration of the Zn d-states. The bonding analysis shows that the C−O interaction is stronger than the C−Zn interaction. So, it generates high stability for these structures. Furthermore, because the development of C/VZnxOy is aimed at lithium battery electrode applications, the most fundamental thing that needs to be examined initially is the interaction between the C/VZnxOy surfaces and the lithium atoms. Li3 strongly binds on all C/VZnxOy surfaces, and it turns to Li3 + based on a simple analysis of charge distribution differences. These findings will have a substantial impact on the future development of ZnO monolayers, and their potential as lithium battery electrodes can be studied further.

Visible Light‐Induced Metal‐free Arylation of Coumarin‐3‐carboxylates with Arylboronic Acids

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Visible Light-Induced Metal-free Arylation of Coumarin-3-carboxylates with Arylboronic Acids

A metal free photoredox strategy for alkenyl C−H arylation has been developed for the first time to synthesize a diverse range of 4-aryl coumarin-2-oxo-3-carboxylate derivatives.


Abstract

The present work represents a novel methodology for the selective arylation of coumarin-3-carboxylates with arylboronic acids via a photochemical route, marking the first-ever attempt for the direct alkenyl C−H arylation using rose bengal as a photocatalyst, which is a readily available and cost-effective alternative to transition metal catalysis. The reaction proceeds smoothly in MeOH/H2O solvent media in the presence of radical initiator affording the arylated products in good yields (60–80 %). The reaction parameters such as visible light, radical initiator, oxidant, anhydrous solvent, and inert atmosphere play a crucial role for the success of this methodology. The substituents present on the substrate show a significant effect on the conversion. This study provides a valuable contribution to the field of organic synthesis offering a new and efficient approach to the arylation of coumarin-3-carboxylic acid esters with a broad substrate scope and high functional group tolerance. It is a versatile method and provides a direct access to biologically relevant 4-arylcoumarin-3-carboxylates.

On the Existence of Pnictogen Bonding Interactions in As(III) S‐Adenosylmethionine Methyltransferase Enzymes

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On the Existence of Pnictogen Bonding Interactions in As(III) S-Adenosylmethionine Methyltransferase Enzymes

This study advances our understanding of As(III) interactions in biological systems, revealing the important role of pnictogen bonding in As(III) S-adenosylmethionine methyltransferases. The noncovalent As⋅⋅⋅O pnictogen bonds have been analyzed energetically and characterized studied using a variety of computational tools.


Abstract

As(III) S-adenosylmethionine methyltransferases, pivotal enzymes in arsenic metabolism, facilitate the methylation of arsenic up to three times. This process predominantly yields trivalent mono- and dimethylarsenite, with trimethylarsine forming in smaller amounts. While this enzyme acts as a detoxifier in microbial systems by altering As(III), in humans, it paradoxically generates more toxic and potentially carcinogenic methylated arsenic species. The strong affinity of As(III) for cysteine residues, forming As(III)-thiolate bonds, is exploited in medical treatments, notably in arsenic trioxide (Trisenox®), an FDA-approved drug for leukemia. The effectiveness of this drug is partly due to its interaction with cysteine residues, leading to the breakdown of key oncogenic fusion proteins. In this study, we extend the understanding of As(III)′s binding mechanisms, showing that, in addition to As(III)−S covalent bonds, noncovalent O⋅⋅⋅As pnictogen bonding plays a vital role. This interaction significantly contributes to the structural stability of the As(III) complexes. Our crystallographic analysis using the PDB database of As(III) S-adenosylmethionine methyltransferases, augmented by comprehensive theoretical studies including molecular electrostatic potential (MEP), quantum theory of atoms in molecules (QTAIM), and natural bond orbital (NBO) analysis, emphasizes the critical role of pnictogen bonding in these systems. We also undertake a detailed evaluation of the energy characteristics of these pnictogen bonds using various theoretical models. To our knowledge, this is the first time pnictogen bonds in As(III) derivatives have been reported in biological systems, marking a significant advancement in our understanding of arsenic‘s molecular interactions.

Synthesis and in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes activity of aldehyde and Schiff base substituted cobalt (II), copper (II), and zinc (II) phthalocyanines

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Synthesis and in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes activity of aldehyde and Schiff base substituted cobalt (II), copper (II), and zinc (II) phthalocyanines

Synthesis and characterization of 4-(5-(diethylamino)-2-formylphenoxy)phthalonitrile, aldehyde-, and Schiff base-substituted peripheral tetra-substituted Co(II), Cu(II), and Zn(II) phthalocyanine compounds. In vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes activity of aldehyde- and Schiff base-substituted cobalt (II), copper (II), and zinc (II) phthalocyanines


In this work, a series of aldehyde-substituted phthalocyanine compounds (1, 3, and 5) were prepared by the cyclotetramerization of the 4-(5-(diethylamino)-2-formylphenoxy) phthalonitrile (a) and the corresponding metal salts. Schiff base-substituted phthalocyanines (2, 4, and 6) were derived from an aldehyde-substituted phthalocyanine (1, 3, and 5) via the reaction of aldehyde-substituted phthalocyanines with an amine reagent. The compounds that were obtained were characterized using FT-IR, 1H {13C} NMR, UV–Vis, and MS spectra (a and 1–6). The inhibitory qualities of synthesized aldehyde and Schiff base-substituted complexes against the enzymes butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) were assessed. The majority of phthalocyanines exhibited strong enzyme-inhibiting properties. Out of the six produced phthalocyanines, 3 and 4 displayed the most intriguing profiles as submicromolar selective AChE inhibitors (IC50 = 0.060 μM), whereas 1 demonstrated the most potent BChE inhibitor (IC50 = 0.024 μM). The aggregation studies of CoPcs, CuPcs, and ZnPcs (1–6) were also carried out in this work.

Electrocatalytic Applications of Carbon Dots and Their Composites

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Carbon dots (CDs) have attracted much attention in the field of electrocatalysis due to their many advantages. These reactions are of great significance for energy conversion and storage, as well as environmental remediation. In this review, we summarize the latest achievements in the electrochemical applications of CDs and their composites, with a focus on environmentally relevant electrocatalysis. We present some representative examples of CDs-based electrocatalysts for different reactions and analyze the catalytic mechanisms and the factors that affect the electrocatalytic performance. Furthermore, we conclude with some challenging issues and future perspectives of this emerging material. This review aims to help readers better understand the application of CDs in the field of electrocatalysis, reveal the reasons that affect electrocatalytic performance, and guide further constructing more efficient, stable, and green electrocatalysts.

Modifications of Protein‐Bound Substrates by Trans‐Acting Enzymes in Natural Products Biosynthesis

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Modifications of Protein-Bound Substrates by Trans-Acting Enzymes in Natural Products Biosynthesis

In polyketide biosynthesis, modifications commonly occur after the completion of the polyketide backbone assembly and the mature products are released from the acyl-carrier protein (ACP). However, exceptions to this rule are widespread, and some are modified on-line by discrete enzymes. This review article highlights more recently reported trans-acting proteins that catalyze modifications of ACP-bound substrates in natural product biosynthesis.


Abstract

Enzymatic modifications of small molecules are a common phenomenon in natural product biosynthesis, leading to the production of diverse bioactive compounds. In polyketide biosynthesis, modifications commonly take place after the completion of the polyketide backbone assembly by the polyketide synthases and the mature products are released from the acyl-carrier protein (ACP). However, exceptions to this rule appear to be widespread, as on-line hydroxylation, methyl transfer, and cyclization during polyketide assembly process are common, particularly in trans-AT PKS systems. Many of these modifications are catalyzed by specific domains within the modular PKS systems. However, several of the on-line modifications are catalyzed by stand-alone proteins. Those include the on-line Baeyer-Villiger oxidation, α-hydroxylation, halogenation, epoxidation, and methyl esterification during polyketide assembly, dehydrogenation of ACP-bound short fatty acids by acyl-CoA dehydrogenase-like enzymes, and glycosylation of ACP-bound intermediates by discrete glycosyltransferase enzymes. This review article highlights some of these trans-acting proteins that catalyze enzymatic modifications of ACP-bound small molecules in natural product biosynthesis.

Molybdenum Catalyzed Acceptorless Dehydrogenation of Alcohols for the Synthesis of Quinolines

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Molybdenum Catalyzed Acceptorless Dehydrogenation of Alcohols for the Synthesis of Quinolines

Molybdenum triazolylidene complexes displayed excellent catalytic activity in the synthesis of a wide variety of quinolines through acceptorless dehydrogenative coupling reactions.


Abstract

The first molybdenum triazolylidene complexes catalyzing the atom-economical synthesis of quinolines through acceptorless dehydrogenative coupling of alcohols is reported. A new family of Mo(0) complexes bearing chelating bis-1,2,3-triazolylidene, pyridyl-1,2,3-triazolylidene, and bis-triazole ligands have been prepared and applied as catalysts for the synthesis of quinolines. Interestingly, Mo complexes bearing bis-1,2,3-triazolylidene ligands with alkyl groups (Et, n-Bu) displayed superior catalytic activities than those containing aryl substituents on the triazolylidene rings. Control experiments corroborated that the catalytic reaction involves the dehydrogenation pathway.

Achieving 78.2 % Faraday Efficiency for Electrochemical Ammonia Production Via Covalent Modification of CNTs with B4C

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Achieving 78.2 % Faraday Efficiency for Electrochemical Ammonia Production Via Covalent Modification of CNTs with B4C

carbon nanotubes (CNTs) have been demonstrated to have far-reaching applications in modifying electrodes, and electrocatalysts due to their high surface area and high mobility for charge carriers. Present study shows a catalyst constructed from covalent modification of CNTs with B4C for electrochemical nitrogen reduction. The formation of new C−B−O covalent bonds was verified by a series of characterizations.


Abstract

Electrochemical reduction of N2 to NH3 provides an alternative to the Haber-Bosch process for sustainable NH3 production driven by renewable electricity. Here, we reported carbon nanotubes (CNTs) covalently modified with boron carbide (B4C) as a nonmetallic catalyst for efficient electrochemical nitrogen reduction reaction (NRR) under ambient conditions. The structure of the catalyst was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), elemental mapping, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The catalyst held a superior selectivity for NRR with high Faraday efficiency of 78.2 % accompanying with NH3 yield rate of 14.0 μg mg−1 cat. h−1 under the condition of 0.1 M Na2SO4 and −0.6 V vs. RHE. Electrochemical experiments including cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization curves were performed to explain the best electrochemical properties of B4C/CNTs among the samples. This work demonstrates that the strategy of covalent modification plays an important role to improve the selectivity of electrochemical NRR catalyst, thus allowing the reactions to proceed more efficiently.