A new approach for characterizing paramagnetic sites in materials is introduced. It combines broadband fast magic-angle spinning (MAS) NMR data with ab initio computed paramagnetic NMR shifts using correlated wave functions. This study presents a challenging example of this. With Fe coordinated in a model compound, the PCN-224 porphyrin metal–organic framework (Fe@PCN-224 MOF) was used to elucidate the coordination geometry and electronic structure using ¹H and ¹³C MAS NMR spectra of the ligand atoms. The computationally predicted ¹³C NMR shifts on the paramagnetic Fe@PCN-224 MOF compared unprecedentedly well with experimental ¹³C NMR shifts and equally well for the diamagnetic counterpart, the Fe-free PCN-224 MOF. This is despite the 25 times wider NMR shift range of 1200 ppm for the paramagnetic Fe@PCN-224 MOF. We conclude that this approach is applicable to crystalline, noncrystalline, and molecular systems.

A novel family of lignin-based thermosets that rely on acetal linkages and do not release hazardous compounds during degradation is proposed as future circular design materials. Poly(ethylene glycol) diisopropenyl ether (PDIP) was utilized as a soft segment to form the acetal linkage with the lignin hydroxyl groups via the addition reaction to the isopropenyl double bond. The use of PDIP instead of previously utilized poly(ethylene glycol) divinyl ether (PDV) prevents the release of harmful acetaldehyde during the acidic hydrolysis of the materials. In addition to the lower toxicity of the degradation products, thermosets with PDIP are more resistant to acidic hydrolysis. Characterization of the thermosets by thermal analysis revealed that the merits of this new lignin-PDIP thermoset extended to increased thermal stability, with T_d5%, T_d30%, and T_s values of 243–253, 349–363, and 152–155 °C, respectively. Furthermore, the developed materials demonstrated intrinsically lower flammability and reduced heat release potential, paving the way for safer materials with a reduced need for potentially harmful flame retardants. The ease of synthesis and high yields achieved encourage further work toward circular and safe materials solutions based on lignin and PDIP.

Lignocellulosic nanofibrils (LCNFs) represent a promising resource-efficient alternative to lignin-free cellulose nanofibrils. Yet, developing eco-friendly pretreatments and energy-efficient disintegration of lignocellulosic biomass is essential to enable the facile production of high-quality LCNFs at low cost. This study addresses these challenges by producing multifunctional phosphorylated lignin-cellulose nanofibrils (PLCNFs) from giant reed fibers. PLCNFs containing 22.1 wt % lignin were produced through direct phosphorylation of unbleached fibers in an H₃PO₄/urea system, followed by alkali-swelling and microfluidization. This simple approach provided a higher yield than conventional lignin-free CNF production. The resulting PLCNFs exhibited a width of 3–5 nm, high aspect ratio, negative zeta potential (-30 mV), and shear-thinning behavior characteristic of a gel-like network. The incorporated phosphate moieties further enhanced flame retardancy. Overall, this work presents an inexpensive, energy-efficient, and sustainable approach to produce multifunctional PLCNFs from unbleached biomass, demonstrating the potential of renewable lignocellulosic resources for developing robust and eco-friendly nanostructured materials.

A novel Mn-based single-atom photocatalyst is disclosed in this study, designed for the dichlorination of alkenes to achieve vicinal dichlorinated products using N-chlorosuccinimide as a mild chlorinating agent, which have widespread applications as pest controlling agents, polymers, flame retardants, and pharmaceuticals. In developing this innovative catalyst, we achieved the atomic dispersion of Mn on aryl-amino-substituted graphitic carbon nitride (f-C3N4). This marks the first instance of a heterogeneous version, offering an operationally simple, sustainable, and efficient pathway for dichlorination of alkenes, including drugs, bioactive compounds, and natural products. This material was extensively characterized by using techniques such as UV-vis spectroscopy, X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), magic-angle spinning (MAS), and solid-state nuclear magnetic resonance (ssNMR) spectroscopy to understand it at the atomic level. Furthermore, mechanistic studies based on multiscale molecular modeling, combining classical reactive molecular dynamics (RMD) simulations and quantum chemistry (QC) calculations, illustrated that the controlled formation of Cl radicals from the in situ formed Mn-Cl bond is responsible for the dichlorination reaction of alkenes. In addition, gram-scale and reusability tests were also performed to demonstrate the applicability of this approach on an industrial scale.

Regioselective C─H bond functionalization is pivotal in modern scientific exploration, offering solutions for achieving novel synthetic methodologies and pharmaceutical development. In this aspect, achieving exceptional regioselective functionalization, like para-selective products in electron-poor aromatics, diverges from traditional methods. Leveraging the advantages of atomically dispersed photocatalysts, we designed a robust photocatalyst for an unconventional regioselective aromatic C─H bond functionalization. This innovation enabled para-selective trifluoromethylations of electron-deficient metadirecting aromatics (─NO₂, ─CF₃, ─CN, etc.), which is entirely orthogonal to the traditional approaches. Mechanistic experiments and DFT analysis confirmed the interaction between Cu-atom and the aromatic substrate, alongside the photocatalyst's molecular arrangement, driving selective exposure of the para-selective functionalization. This strategic approach elucidated pathways for precise molecular transformations, advancing the frontier of regioselective C─H bond functionalization by using atomically dispersed photocatalysts in organic synthesis.

This study focused on CO₂-triggered phase separation in concentrated dispersions of mono-, di-, and triaminated silica for CO₂ capture, based on the hypothesis of reduced regeneration energy coupled with the formation of a CO₂-rich, water-lean sediment. The sedimentation of the CO₂-rich and CO₂-lean dispersions was studied using time-resolved optical transmittance measurements. The CO₂ capacity, reaction rate, diffusivity, and solubility of the dispersions were also studied. The involved CO₂-amine chemistry was studied by using infrared (IR) and cross-polarization solid-state ¹³C and ¹⁵N NMR spectroscopy, and the fluid behavior of the dispersions was studied by rheology. The aminated silica was of the SBA-15 type and characterized by N₂ adsorption and desorption experiments, thermogravimetric analysis, powder X-ray diffraction, scanning and transmission electron microscopy, and crosspolarization solid-state ²⁹Si NMR spectroscopy. The derived energy balances for a simplified process indicated that the regeneration of the CO₂-rich sediments results in an energy demand similar to that of 30 wt % ethanolamine (MEA) in water. The bounds of the energy balances were found to be limited by the somewhat low CO₂ capacities of the dispersions, which underscores the need for increasing the amino group density of the dispersions in future efforts. The observed changes in transmittance between the CO₂-lean and CO₂-loaded dispersions showed that sedimentation occurred within the first 10 min for the CO₂-loaded dispersions, while the CO₂-lean dispersions exhibited no change in transmittance after 60 min. The analysis of the pressure decay curves of the partial CO₂ pressure showed that the absorption rates of the dispersions were smaller than those of monoethanolamine (MEA) in water but were similar to the absorption rates of 2-amino-2-methyl-1-propanol (AMP) in water. The IR spectroscopic analysis was consistent with the formation of ammonium carbamates at a low CO₂ loading and the subsequent formation of HCO₃^– at a higher loading. The flow curves displayed rich and complex fluid behavior, which was strongly affected by the capture of CO₂ by the dispersions. Phenomena such as shear thinning, jamming, and thixotropy were observed.

Nanocellulose is a promising alternative to fossil-derived materials, but its development is hindered by a limited understanding of cellulose–water interactions. Herein, quasielastic neutron scattering (QENS) is used to investigate how hydration and temperature affect the localized rotations in cellulose nanocrystals (CNC) and the diffusion of mobile water. QENS reveals that the C6 hydrogens and the C6 OH in the surface regions of CNC exhibit an isotropic rotation. The extracted mean square displacement shows that hydration enhances the overall hydrogen mobility in the cellulose chains. The mobile water diffusion at 270 K is unaffected by cellulose and consistent with diffusion of supercooled bulk water. At 310 K, the diffusion slows compared to bulk water, consistent with water diffusing on the CNC surface. Decoupling of the translational and rotational motion provides insight into the local cellulose–water motions. The localized motions of the nondiffusing water are found to be coupled with cellulose at 310 K, indicating a more complex dynamics at higher temperature. These findings provide new insights into how hydration modulates hydrogen mobility in cellulose, highlighting the interplay between water diffusion and molecular motion.

Perovskite-type oxyhydrides stand out as hydride-ion conductors of relevance for diverse technological applications, but fundamental questions surrounding the relationship between the mechanism of hydride-ion diffusion and the local structure of these materials remain to be elucidated. Here, in a quasielastic neutron scattering (QENS) study of two perovskite-type oxyhydrides of barium titanate, BaTiO2.67H0.12□0.21 (□ refers to anion vacancies) and BaTiO2.88H0.12, we establish that the mechanism of hydride-ion diffusivity relies on hydride-ion jumps to nearest-neighbor anion vacancies. Combined analyses of QENS and structural data for BaTiO2.67H0.12□0.21 show that the diffusion process is characterized by two different time scales, possibly related to diffusion in regions featured by different concentrations of anion vacancies. It follows that designing materials with specific concentrations of anion vacancies may be an effective route to optimize hydride-ion conductivity toward specific applications.

Green hydrogen is critical to establish a sustainable energy future as it offers a clean, renewable, and a versatile alternative for decarbonizing industries, transportation, and power generation. However, the limitations of current methods significantly restrict the scope and hinder many of the envisioned applications. This study aims to report on the first example of a 3d-metal-based (Cu) heterogeneous photocatalytic system to produce green hydrogen via dehydrogenation of methyl formate (MF), a reaction previously known to require 4d/5d transition metals. Employing a Cu-based atomically dispersed heterogeneous photocatalyst supported on aryl-amino-substituted graphitic carbon nitride (d-gC3N4), the protocol offers numerous key advantages, including the recyclability of the photocatalyst for >10 cycles without significant activity loss, sustained hydrogen production (>15 days!) with high hydrogen yield (19.8 mmol gcat−1) and negligible CO emission, following an operationally simple, sustainable, and efficient catalytic pathway. Furthermore, the photocatalyst is characterized (using HAADF-STEM, SS-NMR, XAS, EPR, and XPS), all of which clearly demonstrated the presence of single atomic Cu-site. Additionally, comprehensive mechanistic investigations together with DFT calculations allow for a thorough mechanistic rationale for this reaction. It is strongly believed that this atomically dispersed heterogeneous photocatalytic approach will open new avenues for establishing liquid organic hydrogen career (LOHC) technologies.

Green hydrogen is widely regarded as a key to a sustainable future, offering a clean and flexible fuel option for decarbonizing the energy, transport, and industrial sectors. While photocatalytic approaches are known for generating hydrogen directly from water, most existing methods require (over)stoichiometric amounts of sacrificial reagents, which is far from ideal for the production of green hydrogen. To address this challenge, we have developed an atomically dispersed Ni-based photocatalyst that achieves hydrogen evolution rates of up to 270 μmol/g/h (168 mmol/g_Ni/h). Remarkably, this photocatalyst also exhibits high photoreactivity under direct sunlight, producing up to 17 μmol/g/h (10.6 mmol/g_Ni/h) of hydrogen. Impressively, the catalyst can even generate green hydrogen directly from seawater, up to 144 μmol/g/h, demonstrating significant potential for real-world applications. The photocatalyst is exceptionally stable, remaining active even after 720 h (140 h of irradiation and 580 h resting time) of operation and retaining high performance over more than 15 cycles. Furthermore, comprehensive spectroscopic and structural analyses─including HRTEM, PXRD, ssNMR, XPS, and XAS─provide detailed structural insights and confirm the atomically dispersed nature of the Ni species. In-depth mechanistic studies have elucidated the critical role of atomic dispersion in enabling robust photocatalytic efficiency.