Frontiers in Chemistry最新文献

The photophysical properties of tris(polypyridyl)ruthenium(II) complex [Ru(dmbpy)₃]²⁺ [dmbpy = 4,4'-dimethyl-2,2'-bipyridine] were investigated and compared with [Ru(bpy)₃]²⁺ following both experimental and computational approaches. The variations in the electronic properties of the complex in the ground and excited states were determined by density functional theory (DFT) methods, and their effects on the anticancer, antioxidant, and antimicrobial activities were also evaluated by molecular docking and dynamic simulation studies. The potential of these complexes to serve as bioanalytes was investigated by their ability to bind with quinones, the well-known electron mediators in numerous light-driven reactions. Following the above, the anticancer properties were evaluated against breast cancer-related proteins. The results revealed that the complex possesses comparable anticancer and antioxidant potential to that of [Ru(bpy)₃]²⁺. The physical, electronic, and biological properties of this complex depend on the nature of the ligands and the medium of investigation. Herein, the potential applications of [Ru(bpy)₃]²⁺ in clinical diagnostics as antioxidants and therapeutic agents were evaluated.

[This corrects the article DOI: 10.3389/fchem.2022.802890.].

Introduction: Bitumen is the viscoelastic fluid binding the crushed stones and mineral aggregates in the asphalt material used to pave roads around the world. During the paving procedure, the volatile compounds are lost and oxidization occurs with variation of the mechanical characteristics (aging); thus, the material becomes rigid and brittle over time and may need replacement. Instead of being landfilled, aged asphalts can be reused in new pavements after pretreatment with specific additives to restore their original properties.

Methods: By considering conscious utilization of natural resources, we propose using the condensable fraction (oil) obtained from the pyrolysis of waste tires (WTs) as the agent to rejuvenate aged bitumen. The pyrolysis oil from WTs was produced and characterized using elemental analysis, gas chromatography coupled with mass spectrometry (GCMS), and thermogravimetry. Bitumen was aged by the rolling thin-film oven test procedure and blended with the WT pyrolysis oil at three different concentrations (1%, 3%, and 6% w/w) to evaluate the rheological behaviors. The blends were also investigated using atomic force microscopy, and the asphaltenic fraction was assessed via optical microscopy.

Results and discussion: All the data consistently indicate that oil addition not only reduces the viscosity of bitumen and restores it to values close to the original unaged bitumen but also changes the intermolecular structure to recover the self-assembly pattern typical of the unaged sample. The physicochemical mechanisms of this phenomenon are proposed in light of the oil characteristics. Hence, it is concluded that the pyrolysis oil from WTs can be used to rejuvenate asphalts, which can then be used in reclaimed asphalt pavement technology. The impacts of our findings are expected to be extensive because bitumens are globally used for paving roads. In addition, since the proposed method couples/fuses urban waste treatment with asphalt maintenance processes, two types of wastes (oil from pyrolysis of WTs and aged bitumens) can be simultaneously recovered and reused to produce new and performing asphalts.

Introduction: New bioactive hybrid materials to prevent biofilm-induced biodeterioration are a significant challenge in indoor environments, where contaminants from microbial films compromise structural integrity and contribute to air pollution, posing health risks from prolonged exposure to biological agents.

Methods: For the first time, diatomaceous earth or diatomite (Dt) was functionalized with quaternary ammonium salt (QAS) and a biogenic compound, citronellol, to develop a bioactive hybrid material (Dt*QC). The hybrids obtained were characterized by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). The antifungal and antibacterial activity were assessed by agar diffusion assay, and micro/macro-dilution tests.

Results and discussion: Characterization confirmed successful functionalization. TGA revealed organic contents of 50.9% with citronellol incorporation reaching 48.1%. SEM-EDS corroborated the incorporation of organic components. FTIR further verified the integration of functional groups while preserving the structural stability of the siliceous framework. Antimicrobial assays revealed a broader range of activity for Dt*QC. For bacterial strains, Dt*QC achieved a minimum inhibitory concentration (MIC) of 0.15 mg/mL against Staphylococcus aureus and demonstrated over 99.9% bacterial reduction, even at lower concentrations. This study highlights a novel approach to developing antimicrobial materials by functionalizing Dt with QAS and citronellol. Overall, these findings underscore the potential of Dt*QC as an advanced antimicrobial material for applications in coatings and preservation systems, offering a sustainable solution to prevent biodeterioration and microbial contamination.

The structure of a nanocatalyst during electrocatalytic reactions often deviates from its pristine structure due to intrinsic properties, or physical and chemical adsorption at the catalytic surfaces. Taking Cu-based catalysts for CO₂ electroreduction reactions (CO₂RR) as an example, they often experience segregation, leaching, and alloying during reactions. With the recent breakthrough development of high-resolution polymer electrochemical liquid cells, in-situ electrochemical liquid cell transmission electron microscopy (EC-TEM) alongside other advanced microscopy techniques, has become a powerful platform for revealing electrocatalysts restructuring at the atomic level. Considering the complex reactions involving electrified solid-liquid interfaces and catalyst structural evolution with intermediates, systematic studies with multimodal approaches are crucial. In this article, we demonstrate a research protocol for the study of electrocatalysts structural evolution during reactions using the in-situ EC-TEM platform. Using Cu and CuAg nanowire catalysts for CO₂RR as model systems, we describe the experimental procedures and findings. We highlight the platform's crucial role in elucidating atomic-scale pathways of nanocatalyst restructuring and identifying catalytic active sites, as well as avoiding potential artifacts to ensure unbiased conclusions. Using the multimodal characterization toolbox, we provide the opportunity to correlate the structure of a working catalyst with its performance. Finally, we discuss advancements as well as the remaining gap in elucidating the structural-performance relationship of working catalysts. We expect this article will assist in establishing guidelines for future investigations of complex electrochemical reactions, such as CO₂RR and other catalytic processes, using the in-situ EC-TEM platform.

In this study, a new MOF (metal-organic framework) based on vanadium and 2,2-bipyridine-4,4-dicarboxylic acid (V/BP-MOF) was synthesized. Synthesized V/BP-MOF was introduced as a strong adsorbent of Congo Red (CR) and an effective agent in eliminating microbial species. In the investigation of CR absorption activity, several factors such as concentration of V/BP-MOF, pH, time, and temperature were investigated. Antimicrobial evaluations were carried out on Common bacterial strains in wastewater and values of MIC (minimum inhibitory concentration) and MBC (Minimum Bactericidal Concentration) were reported. The V/BP-MOF was confirmed and characterized by EA, EDS, EDS mapping, FT-IR, XRD, TGA, BET, SEM, and TEM. In checking the characteristics of V/BP-MOF, size, specific surface area, and thermal stability were obtained, respectively, 68 nm, 325 m²/g, and 320°C. The highest adsorption of CR, at 94%, was obtained at natural pH, ambient temperature, and after 150 min. In kinetic studies, a correlation coefficient of 0.99 was observed with the pseudo-second-order kinetic model, while in isotherm studies, a correlation coefficient of 0.97 was observed with the Freundlich isotherm model. In the biological evaluations, the best inhibition was against Escherichia coli, and MIC and MBC were observed as 4 μg/mL and 2 μg/mL, respectively. As a general result, V/BP-MOF can be introduced as a potent absorbent agent of CR dye and antimicrobial properties. Therefore, the compound synthesized in this study can be introduced as a suitable option for the wastewater treatment industry, with multiple capabilities including the removal of chemical pollutants and pathogenic agents.

Fluorine spin pairs that are constrained in spatial proximity show large scalar spin-spin couplings, despite the atoms being separated by several bonds. This is due to a non-bonded atomic interaction related to partial overlapping of fluorine p-orbitals. In this paper we exploit this phenomenon to create long-lived singlet spin order on the fluorine spin pair. This form of order, which, in this example molecule, is more than an order of magnitude longer than longitudinal order, has the potential to be useful in magnetic resonance imaging and molecular tracing experiments, because of the lack of endogenous fluorine in the human body and the high sensitivity achievable in ¹⁹F NMR.