ChemPlusChem最新文献

The front cover showcases Au single-atoms and clusters stabilized on nanoparticulate edge-faces-rich Mg-Al layered double hydroxides (LDHs), supported on SiO₂ or CeO₂. The catalysts demonstrate impressive activity for aerobic oxidation of alcohols and selective hydrogenation of 4-nitrostyrene. In-situ XAFS and HRTEM reveal the well-dispersed Au(0) single atoms with 1.0 wt% Au loading. The surface OH of LDH NPs effectively stabilize Au and enhances catalytic activity by basic sites of LDH. More details can be found in the Research Article by Tamao Ishida and co-workers (DOI: 10.1002/cplu.202400465).

In this study, two new BOPHY-based derivatives were efficiently synthesized with high yields and characterized by using spectroscopic, electrochemical, and spectroelectrochemical techniques. The introduction of non-conjugated (carbazole (CBZ)) and conjugated (triphenylamine (TPA)) donor groups into the BOPHY macrocycle imparted different electrochemical and spectroscopic properties. Oxidation of BP-2CBZ led to the formation of unstable CBZ radical cations, which further reacted to generate dicarbazole (DCBZ) units, allowing the formation of a polymeric film during anodic cycling. In contrast, BP-2TPA exhibited a reversible oxidation process, generating stable BOPHY and TPA radical cations which inhibited the polymerization process. Spectroscopic differences were also observed, with BP-2CBZ displaying a high fluorescence quantum yield (Ff), while BP-2TPA emission was nearly quenched, exhibiting solvent-dependent fluorescence with a large Stokes shift (~160 nm). BP-2TPA also demonstrated aggregation-induced emission (AIE) properties, showing an increase in fluorescence intensity of around 12 times when the water content changes from 0 to 90%. These experimental findings were further corroborated by DFT and TDDFT calculations. The BP-2CBZ polymer presented electrochromic properties, showing color changes upon oxidation. This work represents the first report of a BOPHY-based polymer synthesized through electrochemical methods.

The present work investigates the impact of the external electric field (EEF) on the oxidizing power of N 2 O, by employing kinetics and quantum chemical calculations. We have taken the oxidation of olefin (Ethene and cyclohexene) by N 2 O as a prototype to demonstrate the effectiveness of EEF. The investigation suggests that the reaction barrier is significantly reduced by choosing an electric field in an appropriate direction. Quantitatively, we found that the rate of EEF catalyzed reaction can be as high as ∼ 13 orders of magnitude compared to the bare reaction.

Electrochemiluminescence (ECL) combines electrochemical redox processes with photochemical light emission, offering exceptional sensitivity, spatial control, and stability. Widely applied in biosensing, medical diagnostics, and environmental monitoring, its efficiency often depends on advanced catalytic materials. Single-atom catalysts (SACs), featuring isolated metal atoms dispersed on a support, have emerged as promising candidates due to their unique electronic structures, high atom utilization, and tunable catalytic properties. These features enable SACs to improve reaction kinetics, enhance light-emitting efficiency, and provide precise control over the generation of excited-state species essential for ECL. This review highlights recent advancements in SACs-boosted ECL systems, with a focus on their reaction mechanisms, design strategies, and roles in improving electrocatalytic and luminescent performance. Additionally, it summarizes the applications of SACs-boosted ECL in bioanalysis, environmental monitoring, and single-particle imaging. By highlighting the synergies between single-atom catalysis and ECL, this work aims to provide a comprehensive overview of the field and a roadmap for future research, paving the way for innovative applications in analytical and sensing technologies.

We have quantum chemically investigated the catalytic effect of hydrogen bonding organocatalysts, (H2N)2C=X (X = O, S, Se, NH, PH, AsH, CH2, SiH2 GeH2), such as urea, on the classic Diels-Alder reaction. All studied hydrogen bond donor catalysts enhance the Diels-Alder reaction between acrolein and 1,3-butadiene to a similar extent. Our activation strain and Kohn-Sham molecular orbital analyses show that these organocatalysts lower the reaction barrier by polarizing the p-orbitals away from the reactive carbon atoms of acrolein, reducing the Pauli repulsion between the reactants. Interestingly, this catalytic mechanism is not limited to >C=X moieties with relatively electronegative X (e.g., O, S, NH) but extends to situations like >C=CH2 and even >C=SiH2.

Cellulose-derived materials, like paper and cellulose acetate, are known to be vulnerable to degradation within museum collections. Studies have been conducted and degradation markers have been identified on these materials. However, the degradation of man-made cellulose-derived fibres in collections is not well understood. This study aims to provide insights into historical cellulose acetate and regenerated cellulose textiles to quantify their physical and chemical changes during degradation using accelerated ageing experiments. Potential physical and chemical markers for degradation were identified, including changes in surface morphology, mass loss, discolouration and changes in spectral bands. These markers can be used to improve understanding of the degradation mechanisms of historical cellulose acetate and regenerated cellulose textiles and guide the development of conservation strategies. These findings have important implications for understanding the stability of man-made cellulosic fibres in museum collections.

The direct effects of ionizing radiation on antibiotics are largely unknown. Here, we report mass spectra of the cationic products of the irradiation of three antibiotics by carbon ions at 10.4 MeV kinetic energy. Carbon ion beams used in cancer treatments have this energy when they deliver the maximum dose to malignant cells. We find that upon single carbon ion collision, extensive fragmentation of antibiotics occurs, predominantly through channels similar to those observed in soft X-ray photoabsorption. However, new product ions are also detected and attributed to the ability of MeV carbon ions to eject electrons from the molecular target in an unspecific manner. Proton transfer appears to play a key role in the dissociation dynamics of rifamycin and actinomycin, and it is complemented by sodium transfer in sodiated rifamycin and its dimer. Importantly, we report the first evidence for abundant loss of H from precursor ions, as well as for intramolecular cross-linking triggered by carbon ion collision. All these processes most probably take place in the vibrationally hot electronic ground state of the molecular system.

Polyoxometalate (POM) gel is well-known but mostly with organic molecules.  Pure inorganic POM gel, i.e., a combination of a 'POM anion and a metal cation', is hardly known and unexplored area of materials research.  When an aqueous solution of sodium tungstate is mixed with an aqueous solution of ferric chloride, the resulting suspension forms a straw-color hydrogel. The behavior of this hydrogel {W72Fe30}HG has been studied by performing rheology studies. Dehydration of hydrogel at room temperature brings about the corresponding xerogel, characterization of which confirms that the xerogel is a {W72Fe30} type giant Keplerate-based POM compound [Fe(H2O)6]14[W72Fe30O252(H2O)72(OH)60]·166H2O ({W72Fe30}XG) and the basic building unit of the gel is {W72Fe30} cluster. The xerogel is macroporous material characterized with 60 hydroxyl groups per formula unit and these hydroxyl groups are acidic in nature. Interestingly, the title xerogel {W72Fe30}XG, which is nothing but an inorganic acid and an inexpensive metal-oxide-based material, exhibits proton conduction in its solid state. The xerogel material shows super proton conductivity of 1.71×10-2 S cm-1 at 80 ⁰C and 98% relative humidity with an activation energy (Ea) of 0.18 eV.

A couple of novel crystalline aluminium(III) derivatives containing tridentate Schiff base ligand (HL) and β-diketones (acetylacetone = acac, benzoylacetone = bnzac, dibenzoylmethane = dbnz) viz [Al(L)bnzac] [Al1], [Al(L)dnbz] [Al2] and [Al(L)acac] [Al3] were synthesized and characterized well using different spectroscopic techniques and elemental analysis. Single crystal X-ray diffraction (SCXRD) analysis of Al2 & Al3 exhibited hexacoordinated geometry around aluminium centre atom. The ring opening polymerization (ROP) of caprolactone (CL) was evaluated to determine the catalytic potential of the complexes Al1-Al3 in absence as well as in presence of benzyl alcohol. IEnd group study was performed using MALDI-TOF spectrometry and 1H NMR spectral analysis verified the existence of the -OBn group as an end group. First order kinetics were found in the monomer aligned with the activated monomer mechanism for the catalysts. Density functional theory (DFT) was carried out to optimize the geometries at B3LYP/LANL2DZ level.

Metal-organic interfaces are critical in organic electronic devices, influencing key performance properties. Understanding these relationships is essential for improving such devices. Polycyclic conjugated hydrocarbons (PCHs) with alternant and non-alternant topologies are promising candidates for exploring these interfaces since they show physisorption and chemisorption, respectively. Using density functional theory with periodic boundary conditions, we modeled the interfaces between a Cu(111) surface and 22 PCHs (11 alternant and 11 non-alternant). We identified quantitative correlations among interface properties, showing that these properties form a "fixed set" of properties for individual molecules. A clear distinction emerges between physisorption and chemisorption for most properties, except for work function changes, which are consistently governed by the Pauli pushback effect resulting from dispersion pull. Interestingly, molecules with larger π-electron systems exhibit stronger dispersion attraction yet higher adsorption heights. This study provides chemically intuitive explanations for these findings and highlights the interconnected nature of interface properties. The insights gained offer valuable guidance for understanding and optimizing Cu(111)-organic interfaces, contributing to advancements in organic electronics.