Precision Chemistry最新文献

Photoresponsive coatings that can change their color in response to light at ambient temperature have large potential applications. Cholesteric liquid crystals (CLCs) are promising photochromic materials, as they are known to reflect light selectively and their optical properties can be modulated with a wide range. However, it remains a major challenge to fabricate photoresponsive coatings that combine fast and good responsivity, fabrication feasibility, and mechanical strength and, more importantly, that can be applied at a large area with excellent stability. In this study, Pickering emulsions containing CLC microdroplets doped with light-driven molecular motors as photoresponsive chiral dopants were prepared via cellulose nanocrystals (CNCs) which serve as both Pickering emulsifiers and alignment agents of CLCs. A melamine–formaldehyde (MF) resin hybrid shell was fabricated via in situ polymerization to form thermally stable CLC microcapsules. These microcapsules were mixed with curable binders, resulting in photoresponsive coatings. The photochromic material which features highly selective addressability of the reflective light wavelength in the visible light region, good reversibility, and viewing angle independence was painted in a large area on both hard and soft substrates, providing a versatile platform for enhanced encryption and smart coatings.

Photoresponsive coatings that can change their color in response to light at ambient temperature have large potential applications. Cholesteric liquid crystals (CLCs) are promising photochromic materials, as they are known to reflect light selectively and their optical properties can be modulated with a wide range. However, it remains a major challenge to fabricate photoresponsive coatings that combine fast and good responsivity, fabrication feasibility, and mechanical strength and, more importantly, that can be applied at a large area with excellent stability. In this study, Pickering emulsions containing CLC microdroplets doped with light-driven molecular motors as photoresponsive chiral dopants were prepared via cellulose nanocrystals (CNCs) which serve as both Pickering emulsifiers and alignment agents of CLCs. A melamine-formaldehyde (MF) resin hybrid shell was fabricated via in situ polymerization to form thermally stable CLC microcapsules. These microcapsules were mixed with curable binders, resulting in photoresponsive coatings. The photochromic material which features highly selective addressability of the reflective light wavelength in the visible light region, good reversibility, and viewing angle independence was painted in a large area on both hard and soft substrates, providing a versatile platform for enhanced encryption and smart coatings.

The past few decades have witnessed significant development in intercalation chemistry research aimed at precisely controlling material properties. Intercalation, as a powerful surface and interface synthesis strategy, facilitates the insertion of external guests into van der Waals (vdW) gaps in two-dimensional (2D) layered materials, inducing various modulation effects (the weakening of interlayer interactions, changes in electronic structures, interfacial charge transfer, and symmetry manipulation) to tailor material properties while preserving intralayer covalent bonds. Importantly, benefiting from the very diverse structures and properties of organic molecules, their intercalation enables the integration of various molecules with a wide array of 2D materials, resulting in the creation of numerous organic–inorganic hybrid superlattices with exotic properties, which brings extensive potential applications in fields such as spintronics, superconductor electronics, optoelectronics, and thermoelectrics. Herein, based on recent advancements in organic intercalation systems, we briefly discuss a summary and classification of various organic guest species. We also discuss three modulation effects induced by organic intercalation and further introduce intriguing modulations in physicochemical properties, including superconductivity, magnetism, thermoelectricity and thermal conductivity, chiral-induced spin selectivity (CISS) effects, and interlayer-confined chemical reaction. Finally, we offer insights into future research opportunities and emerging challenges in organic intercalation systems.

The past few decades have witnessed significant development in intercalation chemistry research aimed at precisely controlling material properties. Intercalation, as a powerful surface and interface synthesis strategy, facilitates the insertion of external guests into van der Waals (vdW) gaps in two-dimensional (2D) layered materials, inducing various modulation effects (the weakening of interlayer interactions, changes in electronic structures, interfacial charge transfer, and symmetry manipulation) to tailor material properties while preserving intralayer covalent bonds. Importantly, benefiting from the very diverse structures and properties of organic molecules, their intercalation enables the integration of various molecules with a wide array of 2D materials, resulting in the creation of numerous organic-inorganic hybrid superlattices with exotic properties, which brings extensive potential applications in fields such as spintronics, superconductor electronics, optoelectronics, and thermoelectrics. Herein, based on recent advancements in organic intercalation systems, we briefly discuss a summary and classification of various organic guest species. We also discuss three modulation effects induced by organic intercalation and further introduce intriguing modulations in physicochemical properties, including superconductivity, magnetism, thermoelectricity and thermal conductivity, chiral-induced spin selectivity (CISS) effects, and interlayer-confined chemical reaction. Finally, we offer insights into future research opportunities and emerging challenges in organic intercalation systems.

Understanding how the electrolyte pH affects electrocatalytic activity is a topic of crucial importance in a large variety of systems. However, unraveling the origin of the pH effects is complicated often by the fact that both the reaction driving forces and reactant concentrations in the electric double layer (EDL) change simultaneously with the pH value. Herein, we employ the hydrogen evolution reaction (HER) at Au(111)-aqueous solution interfaces as a model system to disentangle different pH-dependent factors. In 0.1 M NaOH, the HER current density at Au(111) in the potential range of -0.4 V < E _RHE < 0 V is up to 60 times smaller than that in 0.1 M HClO₄. A reaction model with proper consideration of the local reaction conditions within the EDL is developed. After correcting for the EDL effects, the rate constant for HER is only weakly pH-dependent. Our analysis unambiguously reveals that the observed pH effects are mainly due to the pH-dependent reorganization free energy, which depends on the electrostatic potential and the local reaction conditions within the EDL. Possible origins of the pH and temperature dependence of the activation energy and the electron transfer coefficients are discussed. This work suggests that factors influencing the intrinsic pH-dependent kinetics are easier to understand after proper corrections of EDL effects.

Understanding how the electrolyte pH affects electrocatalytic activity is a topic of crucial importance in a large variety of systems. However, unraveling the origin of the pH effects is complicated often by the fact that both the reaction driving forces and reactant concentrations in the electric double layer (EDL) change simultaneously with the pH value. Herein, we employ the hydrogen evolution reaction (HER) at Au(111)-aqueous solution interfaces as a model system to disentangle different pH-dependent factors. In 0.1 M NaOH, the HER current density at Au(111) in the potential range of −0.4 V < E_RHE < 0 V is up to 60 times smaller than that in 0.1 M HClO₄. A reaction model with proper consideration of the local reaction conditions within the EDL is developed. After correcting for the EDL effects, the rate constant for HER is only weakly pH-dependent. Our analysis unambiguously reveals that the observed pH effects are mainly due to the pH-dependent reorganization free energy, which depends on the electrostatic potential and the local reaction conditions within the EDL. Possible origins of the pH and temperature dependence of the activation energy and the electron transfer coefficients are discussed. This work suggests that factors influencing the intrinsic pH-dependent kinetics are easier to understand after proper corrections of EDL effects.

The shelf-stable heteroleptic borane B(2,6-Cl₂C₆H₃)(3,5-Br₂-2,6-F₂C₆H)₂ (B ⁷ ) efficiently catalyzes the solvent-free hydrogenation of various substituted indoles to indolines with an unprecedented turnover number of 8,500, which is more than 400-fold higher than that reported for B(C₆F₅)₃ under diluted conditions. Mechanistic studies revealed that this hydrogenation proceeds via an olefin-to-nitrogen switching of Lewis bases involved in the H₂-cleavage steps: initially, H₂ cleavage is mediated by a frustrated Lewis pair (FLP) comprising the indole C3-carbon and boron atoms, which then switches to an FLP system comprising the indoline nitrogen and boron atoms after formation of the indoline. This study demonstrates the potential of relatively benign main-group elements for the catalytic synthesis of valuable N-containing molecules using H₂.

The shelf-stable heteroleptic borane B(2,6-Cl₂C₆H₃)(3,5-Br₂-2,6-F₂C₆H)₂ (B⁷) efficiently catalyzes the solvent-free hydrogenation of various substituted indoles to indolines with an unprecedented turnover number of 8,500, which is more than 400-fold higher than that reported for B(C₆F₅)₃ under diluted conditions. Mechanistic studies revealed that this hydrogenation proceeds via an olefin-to-nitrogen switching of Lewis bases involved in the H₂-cleavage steps: initially, H₂ cleavage is mediated by a frustrated Lewis pair (FLP) comprising the indole C3-carbon and boron atoms, which then switches to an FLP system comprising the indoline nitrogen and boron atoms after formation of the indoline. This study demonstrates the potential of relatively benign main-group elements for the catalytic synthesis of valuable N-containing molecules using H₂.