Determination of the origin of capacity fading for substituted phenothiazine within a redox-flow cell. The determination was based on experimental results and theoretical calculations.

The development of aqueous organic redox-flow batteries (AORFB) requires finding new posolyte alternatives to the ferrocyanide salts used presently. Among the potential families, phenothiazine has been reported to be of interest if its solubility in aqueous medium is successfully increased. In this article, the phenothiazine propyl sulfonate (PTZPS) is evaluated as a promising high-potential posolyte for neutral-medium aqueous redox-flow battery. It is demonstrated that electrochemical reversibility is highly dependent on pH, with namely a fast capacity loss in neutral medium. Through the preparation of the oxidized form of this molecule, a kinetic study is performed, confirming the crucial role of the electron transfer step between two molecules at this redox state. Even if density functional theory (DFT) calculations of the electron transfer are not successful due to the significant multireference character of the oxidized form's dyad, using MD simulations, the behavior of the oxidized form in various media is qualitatively predicted, including the effect of addition of chaotropic additives.

Herein, the use of stimuli-responsive poly(disulfide)s as a sealing/coating strategy for porous silicon nanoparticles (pSiNPs) is reported. The polymer matrix is formed in one-pot protocols in water and various payloads could be loaded spontaneously. The engineered hybrid nanoparticles pSiNP-SS demonstrate excellent stability in saline and tunable degradability.

Porous silicon nanoparticles (pSiNPs) represent a unique drug delivery candidate owing to the biocompatibility, degradability, high loading capacity, and production scalability. Various endeavors have been reported to make practical formulations with pSiNPs. However, existing protocols still lack simplicity and sometimes stability in physiological environment. Herein, the use of stimuli-responsive poly(disulfide)s as a sealing/coating strategy for pSiNPs is reported. The polymer matrix is formed in one-pot protocols in water, and various payloads, including small molecule drugs, drug conjugate, and small interfering RNA (siRNA), are loaded spontaneously. The engineered hybrid nanoparticles demonstrated excellent stability in saline and tunable degradability. Drugs like doxorubicin (DOX) and camptothecin (CPT) are loaded physically by polymer entrapment, with loading efficiencies (LE) of 25% and 97%, and payload-silicon ratios (P/Si) of 54% and 97%, respectively. A disulfide-based self-immolative linker (SIL) is also used to covalently load CPT (LE 93%, P/Si 12%). To load siRNA, a polymerizable ionizable lipid (PIL) strategy is developed. siRNA is loaded via electrostatic interactions followed by polymer entrapment (LE 36%, P/Si 14.4%). In vitro experiments reveal the successful delivery of therapeutic candidates in cells. These combined efforts provide a practical solution for the use of pSiNPs in drug delivery.

A carbene-catalyzed oxidative addition (OA) of a C–F bond in hexafluorobenzene to gallylenes was reported. It was shown that the catalytic amount of IMe4 enables the OA of C–F bond to a neutral Ga(I) center of two-coordinate gallylenes having NacNac or Boxm ligand under significantly milder conditions than those previously reported. Tri-coordinate Ga(I)–IMe4 adducts were successfully isolated as an intermediate and structurally characterized. Compared with the reaction of NacNac-gallylene, IMe4 is more efficient in the catalytic reaction of Boxm-gallylene, which may relate to Boxm-gallylene-IMe4 adduct immune to deprotonation of the ligand. DFT calculations supported that the coordination of IMe4 to the Ga(I) center significantly raises the HOMO energy of the gallylene to increase the nucleophilicity at the Ga center.

An acceleration effect of a carbene catalyst toward oxidative addition (OA) of a C–F bond in hexafluorobenzene to gallylenes is reported. It was shown that the catalytic amount of IMe4 (1,3,4,5-tetramethylimidazol-2-ylidene) enables the OA of C–F bond to a neutral Ga(I) center of two-coordinate gallylenes having NacNac (1,3-diketiminate) or Boxm [bis(oxazolinyl)methanide] ligand under significantly milder conditions than those previously reported. Tri-coordinate Ga(I)–IMe4 adducts were successfully isolated as an intermediate and structurally characterized. Compared with the reaction of NacNac-gallylene, IMe4 is more efficient in the catalytic reaction of Boxm-gallylene, which may relate to Boxm-gallylene-IMe4 adduct immune to deprotonation of the ligand. DFT calculations supported that the coordination of IMe4 to the Ga(I) center significantly raises the HOMO energy of the gallylene to increase the nucleophilicity at the Ga center.

A detailed synthetic, crystallographic, and spectroscopic investigation demonstrates that the hitherto elusive di-n-butylcalcium is accessible and stable at low temperature, and can be used for deprotometallation reactions.

The synthesis and detailed characterization by NMR spectroscopy of di-n-butylcalcium are reported. The reaction of [Ca{N(SiMe3)2}2.(thf)2] with equimolar n BuLi in thf at −83 °C generates [Ca( n Bu){N(SiMe3)2}.(thf)3] (6), a complex which evolves toward [Ca{N(SiMe3)(SiMe2-μ-CH2)}.(thf)3]2 (7) upon warming to −35 °C. With two equivalents of the lithium reagent versus [Ca{N(SiMe3)2}2.(thf)2], NMR investigations attest to the formation of [Ca( n Bu)2.(thf)4] (9). Both 6 and 9 are stable in solution at low temperatures. DFT calculations corroborate the stability of the two compounds. In petroleum ether, the reaction of the solvent-free [Ca{N(SiMe3)2}2]2 with 1, 1.5, or 2 equivalents of n BuLi versus Ca reproducibly yields the heterobimetallic aggregate [Ca3(μ- n Bu)4{μ′-N(SiMe3)2}4Li2] (5). The molecular solid-state structures of 5 and 7 have been confirmed by XRD analysis. Unlike the reactions with [Ca{N(SiMe3)2}2.(thf)2], it cannot be asserted that reaction of crystalline [CaI2.(thf)4] with two molar equivalents of n BuLi in thf generates 9, even if the spectroscopic and reactivity data suggest that with equimolar n BuLi, the formation of [Ca( n Bu)(I).(thf)2]2 is clean and quantitative. The protocols described herein for the production of discrete calcium/n-butyl species only require easily accessible calcium precursors. They are readily implantable, and may hence constitute a convenient entry point for broad uptake of alkylcalcium reagents in organic synthesis.

Two NDI-di-NHC metal complexes with Au(I) and Ru(II) are studied, revealing that (Cl)lp…π interactions are strongly governed by geometry and metal identity. In the Au complex, geometry favors intermolecular lp…π and Au–π interactions, while in the Ru complex, this interaction is intramolecular, and induces atropisomerism, enabling quantification of one of the strongest lp…π interactions reported (ΔH≠ = 10.4 kcal mol–1).

Two dimetallic complexes of Au(I) and Ru(II), featuring a naphthalene-diimide (NDI)-linked bis-N-heterocyclic carbene (NHC) ligand, have been synthesized and fully characterized. Spectroscopic analyses, combined with structural data, reveal the presence of lone pair–π (lp–π) interactions between the chloride ligands coordinated to the metal centers and the central NDI unit. The nature of this interaction varies with the metal's coordination geometry: in the di-Au(I) complex, the lp–π interaction is intermolecular, whereas in the di-Ru(II) complex it is intramolecular, leading to the formation of two atropisomers that are distinguishable by conventional spectroscopic techniques. NMR studies of both complexes provided key insights into the lp–π interaction. For the di-Ru(II) complex in particular, these studies enabled the determination of the kinetic and thermodynamic parameters governing the equilibrium between the atropisomers, revealing a barrier to interconversion (ΔH≠) of 10.4 kcal mol– 1, indicative of a strong covalent character in the lp–π interaction.

The mechanical strength of polymer-based electrolyte is one of its important properties. This mini-review summarizes advancements in mechanical enhancement of polymer-based electrolytes for lithium metal batteries and zinc metal batteries. It concludes by discussing the challenges and future directions of improving the mechanical strength of polymer-based electrolytes.

Lithium (Li) and zinc (Zn) metals are promising anode materials for next generation rechargeable metal batteries due to their high theoretical capacities and excellent electrical conductivity. However, uncontrolled dendrite growth can lead to rapid capacity decay, poor electrochemical stability, and limited cycle life. Polymer-based electrolytes with high mechanical strength offer a viable solution. This mini-review begins with an overview of the challenges of polymer-based electrolytes for Li and Zn metal batteries due to insufficient mechanical properties. It then explores recent advancements in the mechanical enhancement strategies. Finally, perspectives on current challenges and future research directions are provided.

In this study, 20 metal catalysts are studied at elevated pressures and temperatures for their ability to perform electrochemical CO2 reduction. Medium catalysts at ambient conditions can become excellent at the proper operating conditions with nearly 100% Faradaic efficiency, but inferior catalysts at ambient conditions do not become excellent by changing the operating conditions.

Traditionally, catalysts for the electrochemical CO2 reduction reaction (CO2RR) have been categorized in four groups: producing either mainly H2, CO, HCOOH, or C2+ products. However, this categorization is based on experiments at ambient conditions. Using a high-pressure, high-temperature electrochemical cell, herein, CO2 reduction is performed at vastly different conditions. Twenty metal catalysts have been screened for their ability to perform CO2 reduction at conditions up to 30 bar and 100 °C at 1.5 V versus SHE in aqueous electrolyte. It is shown that at this potential, catalysts which have average activity at ambient conditions can reach near 100% efficiency for CO2RR at 30 bar and maintain this high efficiency at high temperatures. Both temperature and pressure can increase the CO2RR activity significantly. However, if a catalyst does not perform CO2RR at ambient conditions, increasing pressure and temperature will only increase CO2RR selectivity by up to a maximum of 30%. Nevertheless, some of these inferior CO2RR catalysts at room temperature do show interesting products beyond CO and HCOOH at higher pressure and temperature, such as long-chain hydrocarbons and methanol.

This review summarizes the applications of MOF composites in adsorption, energy storage, catalysis, biomedicine, and sensing. It also discusses the functionality of MOF composites from a dimensional perspective.

Environmental issues have intensified, and demand for energy continues to grow, making it challenging for conventional materials to meet the needs of further exploration in these fields recently. Metal-organic frameworks (MOFs) offer considerable promise for such endeavors owing to their multichannel architecture, large specific surface area, and multifunctional structures. Unfortunately, the inherent instability and unsatisfactory conductivity of original MOFs pose unavoidable challenges in practical applications. Therefore, composites based on MOFs retain the advantages of original MOFs while integrating the functionalities of guest materials (including inorganic carbon materials, metal oxides, and polymers, etc.), are emerging as frontrunners in the future of energy, environment, and biomedical sciences. This article provides a comprehensive review of the applications of MOF composites across various fields, including adsorption, energy storage, catalysis, biomedicine, and sensors. Additionally, it analyzes the physical and chemical properties of various composites based on MOFs from a dimensional viewpoint. In this regard, we not only emphasize the advantages of MOF composites but also provide a detailed analysis and objective overview of their application effects, offering innovative solutions to global challenges.

A pH-programmable site-selective cysteine modification in peptides is reported using a triazine–thiol exchange, termed TriTEx. At acidic pH, internal cysteines are targeted while preserving N-terminal sites; at neutral pH, N-terminal cysteines are selectively modified via an irreversible S–N shift. This strategy provides defined molecular control over cysteine functionalization for precision peptide engineering.

The chemical modification of peptides is a powerful method to enhance their pharmacological properties, including membrane permeability, metabolic stability, and binding affinity. Over recent decades, advances in chemoselective modifications have enabled the construction of well-defined peptide scaffolds with uniform and precise molecular architectures. However, beyond chemoselectivity, achieving true site-selectivity by differentiating between identical amino acids at distinct positions within complex peptide scaffolds remains a key challenge. So far, site-selectivity of cysteine labeling has been largely restricted to N-terminal cysteines. Herein, a programmable strategy for site-selective cysteine modifications is reported, ultimately enabling precise control over the location of cysteine functionalization within peptides. This is accomplished by employing a triazine–thiol exchange, a dynamic covalent reaction with pH-adjustable site-selectivity. It is shown that under acidic conditions internal cysteines are modified while preserving the N-terminal cysteine functionality. Conversely, at neutral pH, site-selective modification of N-terminal cysteines is achieved. The modification of N-terminal cysteines using triazine–thiol exchange proceeds via an S–N shift, which converts the dynamic linkage into an irreversible modification. Density functional theory computations reveal that the site-selectivity originates from modulation of the formed intermediate, providing insights for future mechanism-based designs of site-selective peptide chemistries. The here presented methodology allows chemists to gain control over site-selectivity and unlock new possibilities for precision peptide engineering.

Enaminomaleimides are versatile building blocks for the construction of functionalized heterocycles. Their unique nucleophilic character, contrasting with the classical electrophilic nature of maleimides, enables diverse synthetic applications, showing promising potential in both materials science and medicinal chemistry. This review discusses their synthesis, chemical reactivity, and applications, while also highlighting emerging trends and future perspectives in this evolving field.

Interest in enaminomaleimides has grown significantly over the past decades, as they have proven to be versatile building blocks for the synthesis of functionalized heterocycles. Their unique nucleophilic character, in contrast to the classical electrophilic nature of maleimides, has unlocked new synthetic possibilities, enabling their application across a wide range of chemical transformations. Moreover, their potential extends beyond synthetic chemistry, with promising results reported in both materials science and medicinal chemistry. This review provides a comprehensive overview of the synthesis and chemical applications of enaminomaleimides over time, while also highlighting emerging trends and future directions in this rapidly evolving field.