Mechanistic Applications of Nonlinear Effects in First‐Row Transition‐Metal Catalytic Systems

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Mechanistic Applications of Nonlinear Effects in First-Row Transition-Metal Catalytic Systems


Comprehensive Summary

Knowledge of asymmetric catalytic reaction mechanism is very important for rational design and synthesis of new chiral catalysts or catalytic systems with high catalytic activity and stereoselectivity. The studies of nonlinear effect have attracted wide attentions as a simple and practical mechanistic tool to probe complex asymmetric catalytic reactions. This review documents the application of the study of nonlinear effects on how to reveal the mechanism in asymmetric catalytic reactions that were catalyzed by the first-row transition-metals in the last decade and gives a brief discussion on the different models of nonlinear effect.

Palladium‐Catalyzed Carbonylation of Multifunctionalized Substituted Alkynes to Quinolinone Derivatives under Mild Conditions†

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Palladium-Catalyzed Carbonylation of Multifunctionalized Substituted Alkynes to Quinolinone Derivatives under Mild Conditions†

Fused oxazino-quinolinone derivatives have been obtained in high yield and selectivity by mild palladium-catalyzed carbonylation protocols (atmospheric pressure and mild reaction temperature). Gaseous CO can be replaced with surrogates such as TFBen or hexa-formate calix[6]arenes (CLX[6]CO), which have been employed for the first time as solid carbonylating agents.


Comprehensive Summary

A highly selective palladium-catalyzed carbonylation of 2-alkynylanilines bearing an amide moiety to condensed six-membered heterocyclic structures has been developed under mild conditions (room temperature and atmospheric pressure of CO). The carbonylative protocol is also compatible with CO surrogates, such as benzene-1,3,5-triyl triformate (TFBen) or the newly developed calix[6]arenes functionalized with six formate groups (CLX[6]CO), which are both capable to release CO in situ. A series of tricyclic fused heterocycles containing the important oxazino-quinolinone scaffold have been selectively obtained (only the 6-endo-dig cyclization mode has been observed) in good to excellent yields (up to 99%).

Study of mechanical, optical, and thermoelectric characteristics of Ba2XMoO6 (X = Zn, Cd) double perovskite for energy harvesting

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Study of mechanical, optical, and thermoelectric characteristics of Ba2XMoO6 (X = Zn, Cd) double perovskite for energy harvesting

The dielectric function of Ba2XMoO6 (X = Zn, Cd) double perovskites consists of real and imaginary parts. The real part shows the polarization and dispersion of light energy and imaginary part shows the absorption of light energy. The graphical figure shows the absorption take in the visible and infrared regions which highest peaks at 4.5 eV. Contrary to absorption the polarizations or dispersion of light energy minimum at this point. At resonance frequency the studied materials are completely polarizations, after slight shift of frequency the polarization drops, and maximum absorption of light energy take place.


Abstract

The double perovskites are become the emerging aspirant to fulfill the demand of energy. Therefore, the optoelectronic, elastic and transport characteristics of Ba2XMoO6 (X = Zn, Cd) are addressed systemically. The elastic constants show the mechanical stability. The nature of Ba2ZnMoO6 is brittle and Ba2CdMoO6 is ductile with large values of Debye temperature covalent bonding. The electronic band structures exhibit band gaps of 2.81 and 2.98 eV, which increase their importance for optoelectronic applications. The absorption of light energy, optical loss, refractive index, polarization of light energy are addressed in the energy range zero to 14 eV. Furthermore, thermoelectric characteristics are computed against chemical potentials at 300, 600, and 900 K. The chemical potential decides the p-type nature, with holes as majority carriers. The increasing temperature increases the power factor and figure of merit. Therefore, the optoelectronic and thermoelectric characteristics reveals the importance of studied DPs for energy applications.

Computational Insights on the Hydride and Proton Transfer Mechanisms of D‐Arginine Dehydrogenase

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Computational Insights on the Hydride and Proton Transfer Mechanisms of D-Arginine Dehydrogenase

PaDADH is an amine oxidase that catalyzes the conversion of D-arginine into iminoarginine. The authors formulate computational models based on the ONIOM method to elucidate the oxidation mechanism of D-arginine into iminoarginine using the crystal structure of the enzyme complexed with iminoarginine. The calculations show that the deprotonation step occurs prior to the hydride transfer step, and active site water molecule(s) may have participated in the deprotonation process.


Abstract

D-Arginine dehydrogenase from Pseudomonas aeruginosa (PaDADH) is an amine oxidase which catalyzes the conversion of D-arginine into iminoarginine. It contains a non-covalent FAD cofactor that is involved in the oxidation mechanism. Based on substrate, solvent, and multiple kinetic isotope effects studies, a stepwise hydride transfer mechanism is proposed. It was shown that D-arginine binds to the active site of enzyme as α-amino group protonated, and it is deprotonated before a hydride ion is transferred from its α-C to FAD. Based on a mutagenesis study, it was concluded that a water molecule is the most likely catalytic base responsible from the deprotonation of α-amino group. In this study, we formulated computational models based on ONIOM method to elucidate the oxidation mechanism of D-arginine into iminoarginine using the crystal structure of enzyme complexed with iminoarginine. The calculations showed that Arg222, Arg305, Tyr249, Glu87, His 48, and two active site water molecules play key roles in binding and catalysis. Model systems showed that the deprotonation step occurs prior to hydride transfer step, and active site water molecule(s) may have participated in the deprotonation process.

Photo‐Lipids: Light‐Sensitive Nano‐Switches to Control Membrane Properties

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Photo-Lipids: Light-Sensitive Nano-Switches to Control Membrane Properties

Photo-lipids: trans or cis ? The cover image represents AFM micrographs of phase-separated supported lipid bilayers containing an azobenzene-derived photo-lipid (top & bottom rows). The light-induced isomerization of the azobenzene allows remodeling of the shape of membrane domains. When the photo-lipid adopts a cis-configuration, a fluidification of the membrane is observed as small liquid-disordered (ld) domains (brown) are formed inside the liquid-ordered (lo) phase (gold). In the trans-configuration, the area of the lo domains becomes prominent over that of the ld phase, indicating an increase of membrane order. In the presence of a protein (middle row), cis-isomerization triggers the formation of domains enriched with protein clusters. More information can be found in the Review by Larissa Socrier and Claudia Steinem.


Solid‐state Chromism of Zwitterionic Triarylmethylium Salts

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Solid-state Chromism of Zwitterionic Triarylmethylium Salts

The Front Cover shows the crystal packings of a zwitterionic triarylmethylium salt and Japanese maple leaves. The zwitterion was easily synthesized by one-pot and two-step reactions from potassium 4-bromophenyltris(pentafluorophenyl)borate and exhibits vivid color change in the solid state from green to yellow and then to red by dissolution/evaporation and grinding, respectively. In addition, single crystals of the zwitterionic salts with green, yellow, and red colors could be obtained with different crystal systems, and thus the crystal packings are highlighted with the corresponding colors. Japanese maple leaves turn from green to red, heralding the arrival of autumn. The cover design also reflects a wish for the arrival of the harvest season in chemical research. More information can be found in the Research Article by Y. Mizuhata, N. Tokitoh and co-workers.


Theoretical insight on Cm(III) and Eu(III) competing with Am(III) for binding to N‐donor extractants with different dentate numbers

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Theoretical insight on Cm(III) and Eu(III) competing with Am(III) for binding to N-donor extractants with different dentate numbers

The complexation and bonding nature of Am(III), Cm(III), and Eu(III) ions with 6 N-donor ligands of different dentate numbers were theoretically investigated. The NBO analysis and QTAIM analysis revealed that the Am metal can form more covalent with the ligands than Cm and Eu. Thermodynamic analysis demonstrated effective separation of Am from Cm and Eu, with L4 showing superior performance for Am(III)/Cm(III) separation and L6 excelling in Am(III)/Eu(III) separation.


Abstract

The separation of actinides (An) from lanthanides (Ln) is crucial for nuclear resource recovery and reducing long-term radiotoxicity. While numerous N-donor ligands have been examined for the extraction separation of An and Ln, few studies have investigated the effect of the number of ligand dentate on bonding and extraction separation. To address this issue, we designed six pyridine-based ligands with different numbers of coordination dentate. We employed density functional methods to investigate their bonding properties with Am(III), Cm(III), and Eu(III), as well as the thermodynamic differences in extracting and separating these metal ions. The NBO and QTAIM analyses indicate that the metal–ligand bonds are predominantly ionic. However, the Am-N bond exhibits higher covalency compared to the Cm-N and Eu-N bonds, and it is also stronger than the latter two. This difference in bonding can be attributed to the greater involvement of the 5f orbitals of Am in coordination with the ligands, in contrast to the involvement of the Cm 5f and Eu 4f orbitals. Thermodynamic analysis reveals that the coordination ability of the ligands with metals does increase with the number of coordination teeth. However, the extraction separation effect of the ligand for Am/Cm and Am/Eu does not show a strong correlation with the number of coordination dentate. We hope that this study can offer valuable theoretical support for the design of ligands aimed at the separation of actinide(III) and lanthanide(III) ions.

Synergistic Effect of Allium‐like Ni9S8 & Cu7S4 Electrodeposited on Nickel Foam for Enhanced Water Splitting Activity

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Synergistic Effect of Allium-like Ni9S8 & Cu7S4 Electrodeposited on Nickel Foam for Enhanced Water Splitting Activity

This study investigates a water-splitting process utilizing a biphasic electrodeposited electrode on nickel foam (NF). The *Ni9S8/Cu7S4/NF electrode, reduced with citric acid, exhibits an ultralow overpotential value of 212 mV for OER and 109 mV for HER at the current density of 10 mA cm−2. The electrode demonstrated an excellent stability for 80 hours in pure water splitting and 20 hours in seawater splitting.


Abstract

This study explores a water-splitting activity using a biphasic electrodeposited electrode on nickel foam (NF). The *Ni9S8/Cu7S4/NF electrode with citric acid reduction exhibits superior OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) performance with reduced overpotential and a steeper Tafel slope. The *Ni9S8/Cu7S4/NF electrode displays the ultra-low overpotential value of 212 mV for OER and 109 mV for HER at the current density of 10 mA cm−2. The Tafel slope of 25.4 mV dec−1 for OER and 108 mV dec−1 for HER was found from that electrode. The maximum electrochemical surface area (ECSA), lowest series resistance and lowest charge transfer resistance are found in citric acid reduced electrode, showing increased electrical conductivity and quick charge transfer kinetics. Remarkably, the *Ni9S8/Cu7S4/NF electrode demonstrated excellent stability for 80 hours in pure water splitting and 20 hours in seawater splitting. The synergistic effect of using bimetallic (Cu&Ni) sulfide and enhanced electrical conductivity of the electrode are caused by reduction of metal sulfide into metallic species resulting in improved water splitting performance.