It is generally accepted that the catalytic isomerization of monoterpene epoxides with bicyclo[3.1.1]heptane core (α- and β-pinenes and their derivatives) over Lewis acids predominantly yield carbonyl compounds with cyclopentane ring, whereas Brønsted acids favor the formation of p‑menthene‑type alcohols with a cyclohexane ring. In the present work, a series of layered silicates with varying Mg and Al contents was synthesized hydrothermally and evaluated for the first time as catalysts for the isomerization of verbenol epoxide to p-mentha-1,8-diene-5,6-diol (diol) known as Prottremine, a compound exhibiting high antiparkinsonian activity. Over a synthetic trioctahedral magnesium silicate with a low degree of crystallinity and a predominance of Lewis acid sites (L/B 71), verbenol epoxide was converted predominantly via opening of its bicyclic carbon framework to afford a p-menthene diol with a selectivity of 58%, although this reaction pathway is generally associated with Brønsted acid catalysis. In contrast, weakly acidic aluminosilicates with L/B in the range of 7–15 exhibited low reaction rates and diol selectivities of 45–46%, whereas a synthetic montmorillonite possessing strong Lewis and Brønsted acidity (L/B 0.9) produced ketones as the major products (65%). The dose‑dependent decrease in the reaction rate upon pyridine addition confirms the essential role of Lewis acid sites of magnesium silicate in the reaction. A plausible mechanism for diol formation is proposed. On a 1.5 g scale, magnesium silicate afforded the diol in an isolated yield of 58%, which exceeds that obtained over the benchmark K-10 catalyst (44%). The magnesium silicate catalyst is resistant to leaching and can be recycled with some loss of activity.
Hydrogen production by electrocatalytic water splitting is an important route for sustainable energy conversion, but activating inert basal planes in 2D catalysts remains challenging. In this work, first-principles calculations were used to screen 60 transition-metal and nonmetal (TM-NM) dual-substituted Janus CrSSnN2 structures, from which 47 configurations with high stability were identified. HER activity evaluation further revealed 14 promising candidates with near-thermoneutral hydrogen adsorption (|ΔGH*| < 0.09 eV). Among them, Si-Ni@CrSSnN2 showed the optimal adsorption free energy of ΔGH* = 0.003 eV. To clarify the origin of activity, five machine-learning models were applied to analyze the descriptor-activity relationship. To reduce model-dependent bias and improve prediction robustness, a weighted ensemble model was constructed using sequential least-squares programming (SLSQP). Compared with the individual models, the ensemble model showed more balanced training and testing performance and enabled reliable identification of activity-related descriptor ranges. The results indicate that high HER activity generally requires a d-band center (εd) of -1.2 to 0.1 eV and a TM-H bond length (dTM−H) of 1.58 to 1.73 Å, while the TM-NM distance (dTM−NM) helps regulate local coordination. This work provides a physically interpretable and data-driven guideline for designing efficient Janus CrSSnN2-based HER electrocatalysts.
The Doyle–Kirmse reaction provides direct access to chiral allylic sulfides through sulfur-ylide formation and subsequent [2,3]-sigmatropic rearrangement, although asymmetric control remains challenging. This study reports the engineering of Vitreoscilla hemoglobin (VHb) into a stereoselective biocatalyst for the Doyle-Kirmse reaction, utilizing an integrated strategy that combines computer-aided design, semi-rational protein engineering, and directed evolution. Through this approach, we successfully developed a VHb variant, VHbVF (Y29V/L57F), which serves as a highly efficient and enantioselective catalyst. Under mild conditions (PBS buffer, pH 7.4, 25 °C), the VHbVF-catalyzed model reaction achieved a yield of 98% with an enantiomeric excess (ee) of up to 85%. The biocatalytic system also exhibited a broad substrate scope, accommodating a variety of substituted allyl phenyl thioethers and diazo esters, demonstrating good functional group tolerance and stereoselectivity (up to 85% ee). This work provides the first example of employing engineered VHb for asymmetric Doyle–Kirmse reactions, expanding the catalytic repertoire of hemoproteins in non-natural carbene-transfer chemistry and offering an alternative biocatalytic approach to chiral sulfur-containing compounds.
Herein, we disclose a photocatalytic carbamoylation cascade of unsaturated aldehyde hydrazones with oxamic acids for the modular synthesis of carboxamide-functionalized tetrahydropyridazines and dihydropyrazoles. The reaction proceeds via carbamoyl radical generation and subsequent radical addition/cyclization under metal-free conditions with visible-light irradiation at room temperature. This protocol accommodates a range of substrates with good functional-group compatibility, although reduced efficiency is observed for certain sterically hindered substrates and nitrogen-containing heteroaromatic derivatives, allowing access to diverse N–N heterocycles. The method can be further extended to trifluoromethyl-containing carboxylic acids, Minisci-type carbamoylation, and radical cascade cyclization. The successful implementation of a recirculating-flow photochemical system further highlights the scalability and practical utility of the protocol. Mechanistic experiments and DFT calculations support the proposed radical pathway.
Photoelectrochemical (PEC) catalysis has attracted considerable attention in the context of sustainability, enabling opportunities for solar powered processes such as water splitting to hydrogen, CO2 reduction to hydrocarbons (fuels), or conversion of nitrogen-based species (e.g. nitrates) to ammonia. The PEC catalytic systems considered here entail light absorption, charge generation, bulk charge-carrier transport, recombination, interfacial charge transfer and surface reactions, inherently spanning multiple length and time scales. Such processes have traditionally been developed through chemical intuition and trial-and-error experimentation, but computational methods are increasingly proving useful in guiding innovation in this field. Yet, while electronic-structure methods provide indispensable microscopic descriptors, and continuum models address device-level transport, a persistent gap remains in the handoffs through the mesoscopic regime, where spatial heterogeneity, stochasticity, and non-equilibrium driving forces collectively determine catalytic performance.In this Review, we examine modelling approaches for PEC catalysis across multiple scales. We first discuss recent advances in electronic-structure methods for describing excited states, band alignment, charge localisation, polarons and excitons. We then proceed to explore the atomistic modelling approaches for treating nonadiabatic dynamics, thermally assisted charge transfer, polaron hopping and elementary reaction mechanisms. Finally, we consider mesoscale kinetic and multiscale transport-reaction models, including kinetic Monte Carlo (kMC) and related stochastic approaches, emphasising how different choices of mesoscale state variables enable descriptions of charge transport, reaction kinetics, material evolution and reactor-scale coupling. Building on this multiscale perspective, we discuss emerging challenges specific to PEC catalysis and conclude by outlining future directions towards integrated multiscale modelling frameworks that connect parameter transfer and atomistic reaction energetics with stochastic reaction dynamics and macroscopic PEC performance.
