Heterogenised catalysts for the H-transfer reduction reaction of aldehydes: influence of solvent and solvation effects on reaction performances

Heterogenisation of homogeneous catalysts onto solid supports represents a potential strategy to make the homogeneous catalytic function recyclable and reuseable. Yet, it is usually the case that immobilised catalysts have much lower catalytic activity than their homogeneous counterpart. In addition, the presence of a solid interface introduces a higher degree of complexity by modulating solid/fluid interactions, which can often influence adsorption properties of solvents and reactive species and, ultimately, catalytic activity. In this work, the influence of support and solvent in the H-transfer reduction of propionaldehyde over Al((OPr)-Pr-i)(3)-SiO2, Al((OPr)-Pr-i)(3)-TiO2 and Al((OPr)-Pr-i)(3)-Al2O3 heterogenised catalysts has been studied. Reaction studies are coupled with both NMR relaxation measurements as well as molecular dynamics (MD) simulations in order to unravel surface and solvation effects during the reaction. The results show that, whilst the choice of the support does not influence significantly catalytic activity, reactions carried out in solvents with high affinity for the catalyst surface, or able to hinder access to active sites due to solvation effects, have a lower activity. MD calculations provide key insights into bulk solvation effects involved in such reactions, which are thought to play an important role in determining the catalytic behaviour. The activity of the heterogenised catalysts was found to be comparable with that of the homogeneous Al((OPr)-Pr-i)(3) catalysts for all supports used, showing that for the type of reaction studied immobilisation of the homogeneous catalyst onto solid supports is a viable, robust and effective strategy

CO₂ Reduction by an Iron(I)-Porphyrinate System. Effect of Hydrogen-Bonding in the Second-Coordination Sphere.

Transforming CO2 into valuable materials is an important reaction in catalysis, especially since CO2 concentrations in the atmosphere have been growing steadily due to extensive fossil fuel usage. From an environmental perspective, CO2 reduction into valuable materials should be catalyzed by an environmentally benign catalyst and avoid the use of heavy transition metal ions. In this work we present a computational study into a novel iron(I)-porphyrin catalyst for CO2 reduction, namely with a tetraphenylporphyrin ligand and analogs. In particular, we investigated iron(I)-tetraphenylporphyrin with one of the meso-phenyl groups substituted with ortho-urea, para-urea or ortho-2-amide groups. These substituents can provide hydrogen bonding interactions in the second coordination sphere to bound ligands and assist with proton relay. Furthermore, our studies investigate bicarbonate and phenol as stabilizers and proton donors in the reaction mechanism. Potential energy landscapes for double protonation of iron(I)-porphyrinate with bound CO2 are reported. The work shows that the bicarbonate bridges the urea/amide groups to the CO2 and iron center and provides a tight bonding pattern with strong hydrogen bonding interactions that facilitates easy proton delivery and reduction of CO2. Specifically, bicarbonate provides a low-energy proton shuttle mechanism to form CO and water efficiently. Furthermore, the ortho-urea group locks bicarbonate and CO2 in a tight orientation and helps with ideal proton transfer, while there is more mobility and lesser stability with an ortho-amide group in that position instead. Our calculations show that the ortho-urea group leads to reduction in proton transfer barriers in line with experimental observation. We then applied electric field effect calculations to estimate the environmental effects on the two proton transfer steps in the reaction. These calculations describe the perturbations that enhance the driving forces for the proton transfer steps and have been used to make predictions on how the catalysts can be further engineered for more enhanced CO2 reduction processes

The use of surfactin in inhibiting Botrytis cinerea and in protecting winter jujube from the gray mold

Abstract Surfactin has the potential to be used as a food preservative. However, efficiency and action mechanism in various applications need more assessments and research. In this study, the antifungal effects and the mechanism of action of surfactin on the fungus Botrytis cinerea were investigated. The effects of applying surfactin for the removal of gray mold on the quality of winter jujube were investigated based on the changes in fruit fatty acids. The results showed that (1) surfactin significantly inhibited the growth of B. cinerea, the EC50 at 5 d was 46.42 mg/L. (2) Surfactin significantly reduced the disease incidence and diameter of gray mold-inoculated winter jujube in a concentration-dependent manner. For that treated with surfactin at the EC50, the incidence decreased by 38.89%. (3) For B. cinerea under surfactin treatment, the mycelial morphology changed, the levels of total lipids and ergosterol decreased, the reactive oxygen species levels increased, and the cell integrity was completely damaged. (4) For winter jujube inoculated by B. cinerea, the contents of saturated fatty acids decreased and unsaturated fatty acids increased. For those under the surfactin treatments, winter jujube maintained the fatty acid composition at the level of non-inoculated groups. Mechanical injury significantly changed the fatty acid composition of winter jujube; however, surfactin not only was able to inhibit the growth of gray mold but also mitigated the adverse effects from mechanical injury. The present study demonstrated the potential applications of surfactin in the preservation of postharvest fruit quality

Diagnostic value of galactomannan detection in bronchoalveolar lavage fluid in COVID-19 associated invasive pulmonary fungal infection

Objective To analyze the concentration of galactomannan (GM) in bronchoalveolar lavage fluid (BALF) and its value in the diagnosis of COVID-19 related invasive pulmonary fungal infection(IPFI). Methods From 2022 to 2023, 41 patients with COVID-19 related IPFI confirmed, clinically diagnosed or to be diagnosed in the First Affiliated Hospital of Anhui Medical University were taken as the experimental group, and 42 patients with simple pneumonia were taken as the control group. Bronchoscopic alveolar lavage was performed in both groups, and the contents of GM in both BALF and serum were detected at the same time. The concentration difference and clinical diagnostic value of GM between the two groups of different specimens were analyzed, and ROC was used to evaluate the diagnostic efficacy. Results Compared with the control group, the experimental group had higher BALF GM concentrations [（2.27±1.78） ng/L vs (0.51±0.28) ng/L, t =6.329, P＜0.01) and serum GM concentrations [(1.57±0.56) ng/L vs (0.32±0.11) ng/L, t =14.190, P＜0.01＝. The optimal cut-off value for diagnosing IPFI with BALF was 1.82 ng/L, with sensitivity and specificity of 77.9% and 89.2%, respectively, and AUC of 0.92 (95%CI: 0.871-0.955). The optimal cut-off value for serum was 0.67 ng/L, with sensitivity and specificity of 64.9% and 92.2%, respectively, and AUC of 0.89 (95%CI: 0.854-0.925). However, the false positive rate of BALF was slightly higher than that of serum (10.8% vs 7.8%). Conclusion GM can be serve of as a good indicator for evaluating IPFI related to COVID-19. The GM detection in BALF has more clinical value in the diagnosis of IPFI than serum

High-Purity Fucoxanthin Can Be Efficiently Prepared from Isochrysis zhangjiangensis by Ethanol-Based Green Method Coupled with Octadecylsilyl (ODS) Column Chromatography

The exploitation of new economically valuable microalgae as a sustainable source of minor high-value products can effectively promote the full utilization of microalgae. The efficient preparation of minor products from microalgae remains the challenge, owing to the coexistence of various components with a similar polarity in the microalgae biomass. In this study, a novel approach based on the sustainable-oriented strategy for fucoxanthin (FX) production was proposed, which consisted of four steps, including the culture of microalga, ethanol extraction, ODS column chromatography, and ethanol precipitation. The high-purity FX (around 95%) was efficiently obtained in a total recovery efficiency of 84.28 ± 2.56%. This study reveals that I. zhangjiangensis is a potentially promising feedstock for FX production and firstly provides a potentially eco-friendly method for the scale-up preparation of FX from the microalga I. zhangjiangensis

Isolation and Purification of Fucoxanthin from Brown Seaweed Sargassum horneri Using Open ODS Column Chromatography and Ethanol Precipitation

As an abundant marine xanthophyll, fucoxanthin (FX) exhibits a broad range of biological activities. The preparation of high-purity FX is in great demand, however, most of the available methods require organic solvents which cannot meet the green chemistry standard. In the present study, a simple and efficient purification approach for the purification of FX from the brown seaweed Sargassum horneri was carried out. The FX-rich ethanol extract was isolated by octadecylsilyl (ODS) column chromatography using ethanol–water solvent as a gradient eluent. The overwhelming majority of FX was successfully eluted by the ethanol–water mixture (9:1, v/v), with a recovery rate of 95.36%. A parametric study was performed to optimize the aqueous ethanol precipitation process by investigating the effects on the purity and recovery of FX. Under the optimal conditions, the purity of FX was 91.07%, and the recovery rate was 74.98%. Collectively, the eco-friendly method was cost-efficient for the purification of FX. The developed method provides a potential approach for the large-scale production of fucoxanthin from the brown seaweed Sargassum horneri