Search Results (371)

Metallaphotoredox catalysis merges the powerful bond-forming abilities of transition metal catalysis with unique electron or energy transfer pathways accessible in photoexcited states, injecting new vitality into organic synthesis. However, most transition metal catalysts cannot be excited by visible light. Thus, prevalent metallaphotoredox catalytic systems require dual catalysts: a transition metal catalyst and a separate photosensitizer. This leads to inefficient electron transfer between these two low-concentration catalytic species, which often limits overall photocatalytic performance. Single-atom site catalysts (SASCs) offer a promising solution, wherein isolated and quasi-homogeneous transition metal sites are anchored on heterogeneous supports. When semiconductors are employed as the support, the photosensitive unit and transition metal catalytic site can be integrated into one system. This integration switches the electron transfer mode from intermolecular to intramolecular, thereby significantly enhancing photocatalytic efficiency. Furthermore, such heterogeneous catalysts are easier to separate and reuse. This review summarizes recent advances in the application of SASCs for photocatalytic organic synthesis, with a particular focus on elucidating structure–activity relationships of the single-atom sites. Full article

In the quest for cheap and abundant feedstocks for sustainable hydrogen production, glycerol is emerging as a cost-effective, promising liquid organic hydrogen-rich carrier (LOHC) that can be catalytically activated to produce hydrogen alongside valuable organic products. Selective catalytic acceptorless dehydrogenation of glycerol to lactate and hydrogen gas was achieved with a maximum turnover number (TON_max) of ca. 1600, using a pincer-type ruthenium(II) complex bearing a bis(aminophosphine)pyridine PN³P ligand as a homogeneous catalyst under moderate reaction conditions (24 h, 140 °C) in the presence of KOH as base. NMR experiments and DFT calculations provided insights into key steps of the catalytic process and the energetics of the proposed reaction pathway. Full article

The activation of peracetic acid (PAA) to generate highly reactive species has emerged as a promising advanced oxidation process (AOP) for the degradation of refractory organic pollutants. This review systematically summarizes the recent advancements in PAA-based AOPs, encompassing various activation strategies, underlying reaction mechanisms, and applications across different environmental matrices. The activation methods are critically discussed, including direct energy activation, homogeneous catalysis, and heterogeneous catalysis. The generation process of diverse reactive species, like hydroxyl radicals (HO·), organic radicals (CH₃C(O)O·, CH₃C(O)OO·), and singlet oxygen (¹O₂), was introduced, and their oxidation selectivity and anti-interference ability were compared. Furthermore, the practical applications of PAA-based AOPs in treating wastewater, groundwater, and contaminated soil/sediments are reviewed. Finally, this review outlines critical challenges, including potential toxic byproduct formation, catalyst stability, and economic feasibility, and proposes future research directions to facilitate the transition of PAA-based AOPs from laboratory-scale research to full-scale implementation. This review provides insights for developing efficient, selective, and sustainable oxidation technologies, thereby contributing to the mitigation of emerging contaminant threats and the advancement of environmental remediation practices. Full article

The pervasive contamination of water bodies by refractory organic pollutants necessitates the development of advanced purification technologies. Plasma has emerged as a promising solution, capable of generating a broad spectrum of reactive oxygen and nitrogen species (RONS), UV photons, and electrons in situ, thereby directly degrading contaminants. However, the practical application of plasma-alone systems is often constrained by limited energy efficiency and insufficient mineralization capacity. To overcome these challenges, the integration of plasma with homogeneous advanced oxidation processes (AOPs) has been established as a highly effective strategy. By coupling plasma with catalysts such as peroxymonosulfate (PMS), peracetic acid (PAA), periodate (PI), and Fenton reagents (Fe²⁺/Fe³⁺), a remarkable synergistic effect is achieved. This synergy arises from the multi-modal activation of catalysts by plasma via energetic electrons, UV photolysis, and radical-induced reactions, while the catalysts, in turn, consume long-lived plasma products and regulate reaction pathways. The resultant ‘plasma/catalytic’ system significantly enhances the degradation rate and mineralization efficiency of pollutants, broadens the operational pH window, and improves overall energy utilization. This review systematically examines the mechanisms, performance, and influencing factors of these hybrid systems, and discusses current challenges and future prospects to guide the development of this synergistic technology for sustainable water remediation. Full article

Iminophosphine ligands find extensive applications in homogeneous catalysis; however, their potential antitumor activity is currently being explored. Including biologically active moieties, such as aminoalcohols, could enhance this activity further. Therefore, we have synthesised a novel series of Pd(II) and Pt(II) iminophosphine complexes incorporating aminoalcohols as biologically active moieties to explore the potential of enhancing this activity. The series of Pd(II) complexes includes complexes 2a, 2f, and 2h, which were previously reported by our research group as catalysts in Suzuki–Miyaura cross-coupling reaction in aqueous media. Besides their complete characterisation, some structures have been unequivocally corroborated by single-crystal X-ray diffraction (SC-XRD). To evaluate the cytotoxic potential of the complexes, a preliminary in vitro study was conducted on different cancerous cell lines, including using COS-7 cells as a healthy cell line. Notably, complexes 2e, 2f, and 3b exhibited selectivity towards human chronic myelogenous leukaemia (K562), demonstrating IC₅₀ values of 7.73 ± 1.4 µM, 8.53 ± 1.9 µM, and 8.83 ± 1.5 µM, respectively. Remarkably, the selectivity of these complexes surpassed that of cisplatin. Furthermore, in silico analysis indicated a higher binding energy of these complexes to DNA when compared to cisplatin. Full article

This study researches the underexplored potential of the palladium-catalyzed Hayashi–Miyaura reaction in asymmetric synthesis, focusing on the preparation of novel derivatives of 2,2-diaryl-1-nitroethanes. These compounds are of interest as potential building blocks in medicinal and materials chemistry, yet they remain largely unexamined in enantioselective transformations. The study specifically targets three challenging substrates: 1,3-dimethoxy-5-(2-nitro-1-(o-tolyl)ethyl)benzene, 2-(2-nitro-1-phenylethyl)phenol, and 4-(2-nitro-1-phenylethyl)phenol. These molecules were selected to probe the reaction’s tolerance toward ortho-substitution and free hydroxyl groups—features known to complicate catalytic processes. Full article

Diphenylmethane, recently recognized as a candidate for liquid organic hydrogen carrier systems, is traditionally produced by alkylation of benzene with benzyl chloride using homogeneous catalysts. In the current context, the need for a transition toward processes that reduce environmental impact and move toward sustainability has become increasingly evident. In this work, the benzylation of benzene by benzyl chloride using metal–organic frameworks (MOFs) as catalysts is proposed, as alternative materials that combine the advantages of homogeneous and heterogeneous catalysis. Reaction experiments were carried out in an isothermal batch reactor with commercial Basolite C300 and Basolite F300 MOFs, based on Cu and Fe as active species, respectively. The results demonstrate catalytic activity using both proposed catalysts under the studied conditions, with the results of the Fe-based MOF being more favorable, given the greater standard reduction potential of Fe. Compared with their corresponding metal chlorides, the proposed MOFs improve the alkylation activity. Based on a two-step reaction mechanism, a pseudo first-order kinetic model has been developed for the reaction with MOFs as catalysts. The kinetic parameters were obtained by fitting the model to the experimental data, demonstrating good agreement and validating the proposed mechanistic pathway. Full article

The conversion of CO₂ into valuable chemicals such as formic acid offers a promising approach to reducing CO₂ emissions. This study presents a techno-economic assessment of two continuous catalytic processes for formic acid production via carbon dioxide (CO₂) hydrogenation. The processes differ in the type of nitrogenous base used, operating under either homogeneous or heterogeneous catalytic conditions. Process simulations and techno-economic evaluations were performed in SuperPro Designer^TM for a medium-scale facility with an annual CO₂ processing capacity of around 14 kMT. The homogeneous catalysis pathway demonstrated superior plant performance, producing 13.03 kMT of formic acid per year at 99.78% purity. In contrast, the heterogeneous pathway required higher capital investment and exhibited lower overall efficiency. The techno-economic analysis confirmed the economic viability of the homogeneous process, with a production cost of $1.18/kg and favorable investment indicators, whereas the heterogeneous route proved economically unattractive under the evaluated assumptions. Sensitivity analysis identified the selling price of formic acid as the most critical profitability parameter, with the homogeneous process remaining robust across varying conditions. Overall, homogeneous catalytic CO₂ hydrogenation demonstrates a technically efficient and economically promising process for the chemical transformation of CO₂, contributing to carbon management. Full article

This work reports the synthesis and characterization of a novel rhenium(I) complex incorporating a phosphorus–nitrogen (P,N) ligand. The compound crystallizes in a distorted octahedral geometry, as confirmed by single-crystal X-ray diffraction analysis. The complexes were evaluated as catalysts in the transfer hydrogenation of acetophenone using 2-propanol as the hydrogen source. Comparative studies with other rhenium(I) complexes bearing polypyridine ligands revealed high catalytic performance, achieving conversions between 68% and 99%. These results highlight the promising potential of P,N-ligand rhenium complexes in homogeneous transfer hydrogenation catalysis. The optimal reaction time was found to be 4 h for the complexes studied, with only the fac-[Re(CO)₃(PN)Cl] complex showing improved conversion upon extending the reaction time to 7 h, likely due to the donor effects provided by the P,N-ligand. Full article

Developing a robust Fenton-like catalyst through a feasible method is a significant challenge and is crucial for sustainability in wastewater treatment. Herein, we report a novel dual-phase H₂O₂ activation for ^•OH generation via both heterogeneous surface-mediated reactions and homogeneous radical propagation pathways. Mechanistic investigations revealed that the surface Fe²⁺/Fe³⁺ redox cycle was the primary driver of catalysis at pH 5. Notably, the catalyst produced fewer secondary pollutants than Fenton reactions and was effective in treating pollutants with high concentrations. The oxidative performance of the PAS-ISe was comparable to that of commercial FeSO₄·7H₂O in terms of chemical oxygen demand (COD) removal efficiency and reaction kinetics. Besides, the utility of the catalyst was 2-75-fold greater than that of state-of-the-art Fenton or photo-Fenton-like catalysts. A detailed techno-economic analysis confirmed the feasibility of this strategy and significant cost advantages over existing heterogeneous catalyst synthesis methods. This study concurrently proposes a low-cost approach to valorizing hazardous sludge and effectively treating industrial wastewater, which may support circular economic principles. Full article

Catalysis plays a pivotal role in green chemistry practices, particularly in reducing waste generated during chemical synthesis. Decatungstate (DT) emerges as a potent photocatalyst for Type I oxidations, exhibiting remarkable resilience to oxygen quenching, a characteristic that sets it apart from other excited triplet state photocatalysts. While homogeneous DT catalysis demonstrates effectiveness, its solubility poses challenges for its separation and recycling. To address these limitations, we focus on the development and comparison of heterogeneous DT photocatalysts, aiming to optimize their yield, recovery, and reusability. We synthesized tetrabutylammonium decatungstate (TBADT)-supported catalysts using silica, alumina, titanium dioxide, and glass wool and characterized them using diffuse reflectance measurements. Subsequently, we evaluated their photocatalytic performance by monitoring the oxidation of 1-phenylethanol and cyclohexanol under UVA irradiation. Our findings reveal that TBADT@silica emerges as the most effective catalyst, achieving approximately 20% conversion of cyclohexanol and 50% conversion of 1-phenylethanol with good reusability. Interestingly, we observed that 3-aminopropyl-triethoxysilane (APTES) treatment, intended to enhance DT anchoring, unexpectedly quenches the ³DT* triplet state, reducing catalytic activity. This unexpected finding underscores the importance of careful consideration in designing robust and recyclable heterogeneous decatungstate catalysts. Our research contributes significantly to the advancement of heterogeneous photocatalysis, paving the way for future applications in flow photochemistry. Further, we share a Python code (Google 3.12.11) to correct spectra obtained in Cary spectrometers. Full article

A series of half-titanocenes containing different trialkylsilyl para-phenoxy substituents, Cp*TiCl₂(O-2,6-ⁱPr₂-4-R-C₆H₂) [Cp* = C₅Me₅; R = Si(n-Bu)₃ (5), SiMe₂(n-C₈H₁₇) (6), SiMe₂(t-Bu) (7)], were prepared and identified. Catalytic activity in ethylene polymerization by Cp*TiCl₂(O-2,6-ⁱPr₂-4-R-C₆H₂) [R = H (1), SiMe₃ (2), SiEt₃ (3), Si(i-Pr)₃ (4), 5–7]–MAO (methylaluminoxane) catalysts increased in the following order (in toluene at 25 °C, ethylene 4 atm): R = H (1) < SiMe₃ (2), SiEt₃ (3), Si(i-Pr)₃ (4) < SiMe₂(t-Bu) (7) < SiMe₂(n-C₈H₁₇) (6) < Si(n-Bu)₃ (5, activity = 6.56 × 10⁴ kg-PE/mol-Ti·h). The results thus suggest that the introduction of an alkyl group into a silyl substituent led to an increase in activity. The activities of 5 were affected by the Al/Ti molar ratio (amount of MAO charged), and the highest activity (7.00 × 10⁵ kg-PE/mol-Ti·h) was observed under optimized conditions at 50 °C, whereas the activity decreased at 80 °C. In ethylene copolymerization with 1-dodecene, the Si(n-Bu)₃ analog (5) exhibited remarkable catalytic activity (4.32 × 10⁶ kg-polymer/mol-Ti·h at 25 °C), which was higher than those of the reported catalysts (1–3), affording poly(ethylene-co-1-dodecene)s with efficient comonomer incorporation as observed in 3 [r_E = 3.77 (5) vs. 3.58 (3)]. Full article

In this study, a comprehensive investigation of PET glycolysis has been performed. The research included the development of analytical techniques, experiments with different reactor systems, and the development of mathematical models to understand the kinetics of the process. Quantitative HPLC analysis was adopted and optimized for the detection of BHET, while the size-exclusion chromatography method was developed to determine the molecular weight distribution of solid PET residues. Over 33 experiments were performed with magnetically coupled shaft-stirred Amar reactors, resulting in more than 300 experimentally determined BHET concentration points at various reaction times, temperatures, catalyst concentrations, and ethylene glycol-to-PET ratios. Afterwards, a kinetic model was developed to describe the observed phenomena with a validation step. Full article

In some cases, the catalytic processes involve the formation of self-organized supramolecular structures due to H-bonds and other non-covalent interactions. It has been suggested that the construction of self-assembled catalytic systems is a promising strategy to mimic enzyme catalysis at the model level. As a rule, the real catalysts are not the primary catalytic complexes, but rather, those that are formed during the catalytic process. In our earlier works, we have established that the effective catalysts M(II)_xL¹_y(L¹_ox)_z(L²)_n(H₂O)_m (M = Ni, Fe, L¹ = acac⁻, L² = activating electron-donating ligand) for the selective oxidation of ethylbenzene to α-phenyl ethyl hydroperoxide are the result of the transformation of primary (Ni(Fe)L¹)_x(L²)_y complexes during the oxidation of ethylbenzene. In addition, the mechanism of the transformation to active complexes is similar to the mechanism of action of NiFeARD (NiFe-acireductone dioxygenase). Based on kinetic and spectrophotometric data, we hypothesized that the high stability of effective catalytically active complexes may be associated with the formation of stable supramolecular structures due to intermolecular hydrogen bonds and possibly other non-covalent bonds. We confirmed this assumption using AFM. In this work, using AFM, we studied the possibility of forming supramolecular structures based on iron complexes with L²-crown ethers and quaternary ammonium salts, which are catalysts for the oxidation of ethylbenzene and are models of FeARD (Fe-acireductone dioxygenase). The formation of supramolecular structures based on complexes of natural Hemin with PhOH and L-histidine or Hemin with L-tyrosine and L-histidine, which are models of heme-dependent tyrosine hydroxylase and cytochrome P450-dependent monooxygenases (AFM method), may indicate the importance of outer-sphere regulatory interactions with the participation of Tyrosine and Histidine in the mechanism of action of these enzymes. Full article

Catalytic and bioelectrocatalytic properties of four white rot fungal laccases (Trametes hirsuta, ThL; Coriolopsis caperata, CcL; Steccherinum murashkinskyi, SmL; and Antrodiella faginea, AfL) from different orthologous groups were comparatively studied in homogeneous reactions of electron donor substrate oxidation and in a heterogeneous reaction of dioxygen electroreduction. The ThL and CcL laccases belong to high-redox-potential enzymes (E⁰_T1 = 780 mV), while the AfL and SmL laccases are medium-redox-potential enzymes (E⁰_T1 = 620 and 650 mV). We evaluated the efficiency of laccases in mediatorless bioelectrocatalytic dioxygen reduction by the steady-state potential (E_ss), onset potential (E_onset), half-wave potential (E_1/2), and the slope of the linear segment of the polarization curve. A good correlation was observed between the T1 center potential of the laccases and their electrocatalytic characteristics; however, no correlation with the homogeneous reactions of electron donor substrates’ oxidation was detected. The results obtained are discussed in the light of the known data on the three-dimensional structures of the laccases studied. Full article