Liangliang Huang

Zirconium-based metal–organic frameworks have emerged as promising materials for the capture and detoxification of chemical warfare agents, but the molecular mechanism by which a hierarchical MOF differentiates a hydrophobic reactant from its oxidized product remains incompletely understood. Here, we use molecular dynamics simulations, grand-canonical Monte Carlo adsorption calculations, and periodic density functional theory to examine the dual-hosting behavior of NU-1000 toward sulfur mustard (HD) and mustard sulfoxide (HDO). Rather than treating NU-1000 only as an adsorbent or oxidation catalyst, we resolve how its internal micropore, mesopore, and c-pore interfaces impose distinct confinement environments on reactant and product species. Density functional theory (DFT) calculations show that HD binds most favorably in the c-pore region, with a binding energy of approximately −12.5 kcal/mol, and similarly favorable stabilization in confined micropore environments, whereas substantially weaker binding is observed in the mesopore. Molecular dynamics simulations also reveal sharply different pore residence patterns: HD localizes predominantly in micropores, occupying this region for ∼80% of the trajectory, while HDO samples larger pore environments more broadly, with ∼45% mesopore and ∼34% c-pore occupancy. This pore-selective behavior persists under mixed HD/HDO coadsorption conditions, demonstrating that reactant–product differentiation is intrinsic to the NU-1000 pore network rather than an artifact of isolated single-component simulations. Radial distribution functions further show that HD is stabilized by dispersion-dominated confinement and weak halogen–hydrogen contacts, whereas HDO is governed by more localized, orientation-dependent interactions with hydrated zirconium node sites. These interaction differences produce a pronounced transport asymmetry, with HDO exhibiting a self-diffusion coefficient of 10.6 ± 2.11 × 10–10 m2/s compared with 0.5 ± 0.09 × 10–10 m2/s for HD at comparable loading. The results identify NU-1000 as a dual-function molecular host that couples reactant retention with product mobility, providing an interface-level mechanism relevant to selective CWA detoxification and confined transport in hierarchical porous catalysts.

Vitrimers are covalent adaptable networks that combine the structural stability of thermosets with self-healing enabled by dynamic covalent bonds. However, the molecular-level interplay among polymerization, prescribed bond-exchange reactions (BERs), finite-time mechanical relaxation, and nanoscale interfacial recovery remains incompletely understood. Here, we employ all-atom molecular dynamics simulations with the REACTER template-based reaction algorithm to construct a Bis-GMA/2-HEMA methacrylate polymer assembly and to model temperature-dependent transesterification. The resulting structure exhibits heterogeneous connectivity and a simulated glass transition temperature consistent with reported trends. With the imposed BER-acceptance window centered near the simulated T_g, mechanical and self-healing analyses reveal a model-conditioned temperature crossover. Near the glass transition region, BERs cooperate with emerging segmental mobility to accelerate finite-time mechanical relaxation and early-stage healing. At higher temperatures, thermally activated chain mobility and physical interfacial reconsolidation dominate the apparent response, making the incremental contribution of BERs secondary. Because the glass transition temperature and the topology-freezing temperature are distinct and the latter is not calculated here, the near-transition crossover is interpreted as conditional on the adopted BER schedule rather than as a universal vitrimer rule. These results clarify how dynamic covalent chemistry and temperature-controlled relaxation jointly regulate nanoscale vitrimer mechanics and repair within the accessible simulation window.

First-principles calculations show that angstrom-scale slit confinement alone activates O2 via the coupled spin, charge, and bonding reconfiguration. Across electronically distinct walls (graphene, h-BN, and g-C3N4), reducing the gap drives a stepwise evolution from triplet O2 to superoxide-like and spin-quenched peroxo-like states, followed by O–O scission and surface chemisorption. A pressure-gap relation exhibits a sharp signature at the crossover, suggesting the confinement-driven generation of reactive oxygen species without dopants, photons, or external fields.

Light-driven isotopic labeling is currently dominated by homogeneous catalysis and largely relies on separate thiol-based hydrogen-atom-transfer catalysts. Metal–organic frameworks (MOFs), with their modular structures, confined pore environments, and tunable optoelectronic properties, offer an attractive but largely unexplored heterogeneous platform for controlled isotopic incorporation in chemicals. Herein, we report a systematic investigation of MOF-photocatalyzed hydrogen/deuterium (H/D) exchange, demonstrating that UiO-66-type materials uniquely enable thiol-free, formyl-selective deuteration of aromatic aldehydes using D2O as the sole deuterium source. Under UV irradiation, UiO-66 materials achieve up to 97% H/D incorporation over 3 h with 99% product selectivity, a level of control far surpassing that of catalyst-free photochemistry. Evaluation of the influence of linker functionalization shows that efficiency depends on multiple interdependent parameters, including radical generation, porosity, substrate binding and diffusion, and D2O accessibility, thereby establishing it as a key design handle for controlling reactivity in H/D exchange. Mechanistic investigations using electron paramagnetic resonance spectroscopy, controls using isotopically enriched UiO-66 and zirconium oxo clusters, and density functional theory analysis demonstrate that the Zr6O4(OH)4 nodes actively participate in catalysis, enabling deuterium transfer via proton-coupled electron-transfer mechanisms involving in situ-generated μ3-OD groups. Aldehyde confinement at the Zr6-cluster surface suppresses competing oxidation pathways and promotes a surface-confined radical mechanism that is inaccessible to homogeneous photocatalysts. Our findings establish UiO-66 as a single-component heterogeneous photocatalyst for selective isotopic labeling and mechanistically probe a previously unexplored mode of node-centered photoreactivity in MOFs. This work provides mechanistic insights into the use of MOFs for isotopic labeling and late-stage functionalization under mild conditions, highlighting the role of node-centered photochemistry.

To apply molecular dynamics (MD) simulations in the study of virgin asphalt binder, researchers have relied on basis sets of representative model structures from the SARA categories of saturated aliphatics (S), naphthenic aromatics (A), polar aromatics or resins (R), and asphaltenes (A). The evolution of these model compounds for MD of binder is reviewed with emphasis on addition of oxidized species for simulations of recycled aged binders. The level and type of oxygen functional groups in many MD simulations are not consistent with reported findings. Oxidation of primary, secondary, and tertiary benzylic carbons has been used as a rational approach to generate an extended basis set with functional groups reflecting ageing of virgin binder model compounds. Moieties known to be present in aged binder, though not wholly represented in prior work, include carboxylic acids, ketones, alcohols, anhydrides, and sulfoxides. A specific modified basis set for oxidized asphalt binder is proposed along with a methodology for generating other oxygen-consistent basis sets from virgin binder structures. An example illustrates how selection of compounds from the modified basis set and their amounts can be used to match observed functional group compositions. The objective of this approach is more realistic representation of the molecular interactions between aged asphalt binder structures and those in a waste cooking/motor oil, for example, used to rejuvenate the rheological properties of a binder.

In a biological medium, nanoparticles (NPs) can spontaneously interact with proteins, adsorb onto their surface, and cause conformational and orientation changes of the proteins. As a result, the protein function is influenced in a complex manner. Therefore, a detailed understanding of the nature and specificity of protein–nanoparticle interactions is crucial for the application of functional NPs in medicine. In the presented work, we studied the interactions of GMA-treated SiO₂ NPs with the Fe₃O₄ core and attached carborane compounds (Fe₃O₄/TEOS/TMSPM/GMA/Carborane), designed for boron neutron capture therapy, with human serum albumin (HSA) and insulin. We combined different techniques: spectrofluorometry, circular dichroism spectroscopy, and isothermal titration calorimetry to address this issue. The results show that the adsorption of protein onto the NP surface is enthalpy–entropy-driven, with ensuing structural changes of the protein. As for albumin, the percentage of the α-helix structure in the protein is significantly reduced from 87.59 (free protein) to 40.9% for an NP concentration of 1.8 mg/mL, while the content of the β-sheet and random coil increases from 0.48 to 8.78% and from 11.93 to 50.32%, respectively. The interaction between NPs and small protein–insulin is weaker than that for HSA, confirming less negative ΔH and a 15% decrease in the α-structure content for the highest concentration of NPs. For both proteins, the exposure on Fe₃O₄/TEOS/TMSPM/GMA/Carborane affects the polarity of the microenvironment around Trp, which is consequently exposed to a more hydrophobic environment. Calculated values of the radius of gyration and the minimum distance between the proteins and the NPs indicate a stronger interaction and closer binding proximity to the NPs, corroborating experimental observations of the higher binding affinity of HSA to NPs.

Aluminosilicates enable direct C–C bond formation of furans with naturally sourced allylic alcohols at room temperature. C(sp²)–H alkylation shows structure-dependent efficiency and selectivity.