Molecules

11 pages, 3356 KiB

Open AccessArticle

Identification of Key Volatile Compounds in Tilapia during Air Frying Process by Quantitative Gas Chromatography–Ion Mobility Spectrometry

by Tianyu Chen, Yong Xue, Chunsheng Li, Yongqiang Zhao, Hui Huang, Yang Feng, Huan Xiang and Shengjun Chen

Molecules 2024, 29(18), 4516; https://doi.org/10.3390/molecules29184516 - 23 Sep 2024

Abstract

Air frying as a new roasting technology has potential for roasted fish production. In this study, the changes in volatile compounds (VCs) during air frying of tilapia were studied by quantitative gas chromatography–ion mobility spectrometry, followed by the identification of key VCs based [...] Read more.

Air frying as a new roasting technology has potential for roasted fish production. In this study, the changes in volatile compounds (VCs) during air frying of tilapia were studied by quantitative gas chromatography–ion mobility spectrometry, followed by the identification of key VCs based on their odor activity value (OAV). There were 34 verified VCs, of which 16 VCs were identified as the key VCs with OAV ≥ 1. Most of the VCs were improved by air frying and peaked at 20 min. During the air frying, the total sulfhydryl content markedly decreased, while the protein carbonyl and MDA content significantly increased, suggesting the enhancement in the oxidation of lipids and proteins. The correlation network among the chemical properties and key VCs was constructed. The change in total sulfhydryl, protein carbonyl, and MDA showed significant correlation with most of the key VCs, especially 2-methyl butanal, ethyl acetate, and propanal. The results indicated that the oxidation of lipids and proteins contributed the most to the flavor improvement in air-fried tilapia. This study provides a crucial reference for the volatile flavor improvement and pre-cooked product development of roasted tilapia. Full article

(This article belongs to the Section Food Chemistry)

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15 pages, 2730 KiB

Open AccessArticle

Broadband Solar Absorber and Thermal Emitter Based on Single-Layer Molybdenum Disulfide

by Wanhai Liu, Fuyan Wu, Zao Yi, Yongjian Tang, Yougen Yi, Pinghui Wu and Qingdong Zeng

Molecules 2024, 29(18), 4515; https://doi.org/10.3390/molecules29184515 - 23 Sep 2024

Abstract

In recent years, solar energy has become popular because of its clean and renewable properties. Meanwhile, two-dimensional materials have become a new favorite in scientific research due to their unique physicochemical properties. Among them, monolayer molybdenum disulfide (MoS₂), as an outstanding [...] Read more.

In recent years, solar energy has become popular because of its clean and renewable properties. Meanwhile, two-dimensional materials have become a new favorite in scientific research due to their unique physicochemical properties. Among them, monolayer molybdenum disulfide (MoS₂), as an outstanding representative of transition metal sulfides, is a hot research topic after graphene. Therefore, we have conducted an in-depth theoretical study and design simulation using the finite-difference method in time domain (FDTD) for a solar absorber based on the two-dimensional material MoS₂. In this paper, a broadband solar absorber and thermal emitter based on a single layer of molybdenum disulfide is designed. It is shown that the broadband absorption of the absorber is mainly due to the propagating plasma resonance on the metal surface of the patterned layer and the localized surface plasma resonance excited in the adjacent patterned air cavity. The research results show that the designed structure boasts an exceptional broadband performance, achieving an ultra-wide spectral range spanning 2040 nm, with an overall absorption efficiency exceeding 90%. Notably, it maintains an average absorption rate of 94.61% across its spectrum, and in a narrow bandwidth centered at 303 nm, it demonstrates a near-unity absorption rate, surpassing 99%, underscoring its remarkable absorptive capabilities. The weighted average absorption rate of the whole wavelength range (280 nm–2500 nm) at AM1.5 is above 95.03%, and even at the extreme temperature of up to 1500 K, its heat radiation efficiency is high. Furthermore, the solar absorber in question exhibits polarization insensitivity, ensuring its performance is not influenced by the orientation of incident light. These advantages can enable our absorber to be widely used in solar thermal photovoltaics and other fields and provide new ideas for broadband absorbers based on two-dimensional materials. Full article

(This article belongs to the Special Issue Two-Dimensional Materials: From Synthesis to Applications)

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10 pages, 1336 KiB

Open AccessArticle

A New Process for the Synthesis of Budesonide 21-Phosphate and Evaluation in a Murine Model of Inflammation

by Angela Corvino, Elisabetta Granato, Antonia Scognamiglio, Ferdinando Fiorino, Francesco Frecentese, Elisa Magli, Elisa Perissutti, Vincenzo Santagada, Giuseppe Cirino, Ida Cerqua, Rocco Pavese, Antonio Petti, Francesca Pavese, Francesco Petti, Fiorentina Roviezzo, Beatrice Severino and Giuseppe Caliendo

Molecules 2024, 29(18), 4514; https://doi.org/10.3390/molecules29184514 - 23 Sep 2024

Abstract

In this study, a new and straightforward process for the preparation of budesonide 21-phosphate (Bud-21P) and its disodium salt (Bud-21P-Na2) is described. The method results in a yield comparable to those obtained by diphosphoryl chloride, but it is more manageable, less expensive, and [...] Read more.

In this study, a new and straightforward process for the preparation of budesonide 21-phosphate (Bud-21P) and its disodium salt (Bud-21P-Na2) is described. The method results in a yield comparable to those obtained by diphosphoryl chloride, but it is more manageable, less expensive, and safer. The new compounds are characterized by better water solubility compared to the parent compound. Moreover, they have been evaluated for their anti-inflammatory activity and the obtained results clearly evidence that Bud-21P and Bud-21P-Na2 retained anti-inflammatory activity like the parent compound budesonide (Bud) in mice with cutaneous induced edema. Full article

(This article belongs to the Section Medicinal Chemistry)

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13 pages, 4579 KiB

Open AccessArticle

Unveiling the Influences of In Situ Carbon Content on the Structure and Electrochemical Properties of MoS₂/C Composites

by Bofeng Zhang, Junyao Zhao, He Zhang, Jian Tian, Yang Cui and Wenjun Zhu

Molecules 2024, 29(18), 4513; https://doi.org/10.3390/molecules29184513 - 23 Sep 2024

Abstract

In this work, a MoS₂/C heterostructure was designed and prepared through an in situ composite method. The introduction of carbon during the synthesis process altered the morphology and size of MoS₂, resulting in a reduction in the size of [...] Read more.

In this work, a MoS₂/C heterostructure was designed and prepared through an in situ composite method. The introduction of carbon during the synthesis process altered the morphology and size of MoS₂, resulting in a reduction in the size of the flower-like structures. Further, by varying the carbon content, a series of characterization methods were employed to study the structure and electrochemical lithium storage performance of the composites, revealing the effect of carbon content on the morphology, structure characteristics, and electrochemical performance of MoS₂/C composites. The experimental setup included three sample groups: MCS, MCM, and MCL, with glucose additions of 0.24 g, 0.48 g, and 0.96 g, respectively. With increasing carbon content, the size of MoS₂ initially decreases, then increases. Among these, the MCM sample exhibits the optimal structure, characterized by smaller MoS₂ dimensions with less variation. The electrochemical results showed that MCM exhibited excellent electrochemical lithium storage performance, with reversible specific capacities of 956.8, 767.4, 646.1, and 561.4 mAh/g after 10 cycles at 100, 200, 500, and 1000 mA/g, respectively. Full article

(This article belongs to the Special Issue 2D Nanosheets and Their Nanohybrids)

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20 pages, 25267 KiB

Open AccessArticle

Cu-ZnO Embedded in a Polydopamine Shell for the Generation of Antibacterial Surgical Face Masks

by Nicola d’Alessandro, Francesca Coccia, Luca Agostino Vitali, Giorgia Rastelli, Amedeo Cinosi, Andrea Mascitti and Lucia Tonucci

Molecules 2024, 29(18), 4512; https://doi.org/10.3390/molecules29184512 - 23 Sep 2024

Abstract

A new easy protocol to functionalize the middle layer of commercial surgical face masks (FMs) with Zn and Cu oxides is proposed in order to obtain antibacterial personal protective equipment. Zinc and copper oxides were synthesized embedded in a polydopamine (PDA) shell as [...] Read more.

A new easy protocol to functionalize the middle layer of commercial surgical face masks (FMs) with Zn and Cu oxides is proposed in order to obtain antibacterial personal protective equipment. Zinc and copper oxides were synthesized embedded in a polydopamine (PDA) shell as potential antibacterial agents; they were analyzed by XRD and TEM, revealing, in all the cases, the formation of metal oxide nanoparticles (NPs). PDA is a natural polymer appreciated for its simple and rapid synthesis, biocompatibility, and high functionalization; it is used in this work as an organic matrix that, in addition to stabilizing NPs, also acts as a diluent in the functionalization step, decreasing the metal loading on the polypropylene (PP) surface. The functionalized middle layers of the FMs were characterized by SEM, XRD, FTIR, and TXRF and tested in their bacterial-growth-inhibiting effect against Klebsiella pneumoniae and Staphylococcus aureus. Among all functionalizing agents, Cu₂O-doped-ZnO NPs enclosed in PDA shell, prepared by an ultrasound-assisted method, showed the best antibacterial effect, even at low metal loading, without changing the hydrophobicity of the FM. This approach offers a sustainable solution by prolonging FM lifespan and reducing material waste. Full article

(This article belongs to the Special Issue Preparation, Characterization and Application of Biochemical Antimicrobial Materials and Compounds)

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17 pages, 6266 KiB

Open AccessArticle

Mono- and Binuclear Complexes in a Centrifuge-Less Cloud-Point Extraction System for the Spectrophotometric Determination of Zinc(II)

by Kiril B. Gavazov, Petya V. Racheva, Antoaneta D. Saravanska, Fatma Genc and Vassil B. Delchev

Molecules 2024, 29(18), 4511; https://doi.org/10.3390/molecules29184511 - 23 Sep 2024

Abstract

The hydrophobic reagent 6-hexyl-4-(2-thiazolylazo)resorcinol (HTAR) was investigated as part of a cloud-point extraction (CPE) system for the spectrophotometric determination of Zn(II). In the system, complexes with different stoichiometries, including 1:1 and 2:2 (Zn:HTAR), are formed. Their ground-state equilibrium geometries were optimized at the [...] Read more.

The hydrophobic reagent 6-hexyl-4-(2-thiazolylazo)resorcinol (HTAR) was investigated as part of a cloud-point extraction (CPE) system for the spectrophotometric determination of Zn(II). In the system, complexes with different stoichiometries, including 1:1 and 2:2 (Zn:HTAR), are formed. Their ground-state equilibrium geometries were optimized at the B3LYP/6-31G level of theory. The obtained structures were then used to calculate vertical excitation energies in order to generate theoretical UV/Vis absorption spectra. The comparison between theoretical and experimental spectra demonstrated that, under optimal conditions, a binuclear complex containing oxygen-bridging atoms is the dominant species. The absorbance was found to be linearly dependent on the concentration of Zn(II) within the range of 15.7 to 209 ng mL⁻¹ (R² = 0.9996). The fraction extracted (%E), logarithm of the conditional extraction constant (log K_ex), and molar absorption coefficient (ε) at λ_max = 553 nm were calculated to be 98.3%, 15.9, and 4.47 × 10⁵ L mol⁻¹ cm⁻¹, respectively. The method developed is characterized by simplicity, convenience, profitability, sensitivity, and ecological friendliness. It has been successfully applied to the analysis of pharmaceutical and industrial samples. Full article

(This article belongs to the Special Issue Molecular Reactivity: Theoretical Study and Interpretation of Experimental Results—2nd Edition)

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17 pages, 1642 KiB

Open AccessArticle

Formulating Sustainable Emulsions: Mandelic Acid and Essential Oils as Natural Preservatives

by Jana Pavlačková, Pavlína Egner, Pavel Mokrejš and Magda Janalíková

Molecules 2024, 29(18), 4510; https://doi.org/10.3390/molecules29184510 - 23 Sep 2024

Abstract

Emulsion products with natural antimicrobials are becoming increasingly popular for topical application. Mandelic Acid is interesting in cosmetics due to its potent exfoliating properties, which have driven advancements in skincare technologies. Essential oils have various properties, of which the most useful in cosmetics [...] Read more.

Emulsion products with natural antimicrobials are becoming increasingly popular for topical application. Mandelic Acid is interesting in cosmetics due to its potent exfoliating properties, which have driven advancements in skincare technologies. Essential oils have various properties, of which the most useful in cosmetics are those that do not cause irritation, smell pleasant, and have other beneficial properties such as antimicrobial effects. Emulsions with Mandelic Acid and essential oils from Satureja montana, Lemongrass, and Litsea cubeba were formulated and microbiologically tested for their preservative effectiveness. The effect of the treatments on skin condition was monitored by non-invasive diagnostic methods, such as hydration, transepidermal water loss, and pH value. Sensory analysis revealed that the matrix containing Mandelic Acid alone or combined with Litsea Cubeba Oil was the best-performing formulation, consistent with the compliant results of antimicrobial efficacy. The topical form of this cosmetic product has demonstrated excellent preservative activity and desirable biophysical efficacy on the skin. Full article

(This article belongs to the Special Issue Functional Molecules as Novel Cosmetic Ingredients)

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13 pages, 1145 KiB

Open AccessArticle

On the Simulation of Photoreactions Using Restricted Open-Shell Kohn–Sham Theory

by Ralf Büchel, Luis Álvarez, Jan Grage, Dominykas Maniscalco and Irmgard Frank

Molecules 2024, 29(18), 4509; https://doi.org/10.3390/molecules29184509 - 23 Sep 2024

Abstract

It is a well-established standard to describe ground-state chemical reactions at an ab initio level of multi-electron theory. Fast reactions can be directly simulated. The most widely used approach is density functional theory for the electronic structure in combination with molecular dynamics for [...] Read more.

It is a well-established standard to describe ground-state chemical reactions at an ab initio level of multi-electron theory. Fast reactions can be directly simulated. The most widely used approach is density functional theory for the electronic structure in combination with molecular dynamics for the nuclear motion. This approach is known as ab initio molecular dynamics. In contrast, the simulation of excited-state reactions at this level of theory is significantly more difficult. It turns out that the self-consistent solution of the Kohn–Sham equations is not easily reached in excited-state simulations. The first program that solved this problem was the Car–Parrinello molecular dynamics code, using restricted open-shell Kohn–Sham theory. Meanwhile, there are alternatives, most prominently the Q-Chem code, which widens the range of applications. The present study investigates the suitability of both codes for the molecular dynamics simulation of excited-state motion and presents applications to photoreactions. Full article

(This article belongs to the Special Issue Molecular Reactivity: Theoretical Study and Interpretation of Experimental Results—2nd Edition)

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26 pages, 13815 KiB

Open AccessReview

Engineering of Green Carbon Dots for Biomedical and Biotechnological Applications

by Junjie Shang, Qian Zhou, Kehan Wang and Yunlin Wei

Molecules 2024, 29(18), 4508; https://doi.org/10.3390/molecules29184508 - 23 Sep 2024

Abstract

Carbon dots (CDs) are attracting increasing research attention due to their exceptional attributes, including their biocompatibility, water solubility, minimal toxicity, high photoluminescence, and easy functionalization. Green CDs, derived from natural sources such as fruits and vegetables, present advantages over conventionally produced CDs, such [...] Read more.

Carbon dots (CDs) are attracting increasing research attention due to their exceptional attributes, including their biocompatibility, water solubility, minimal toxicity, high photoluminescence, and easy functionalization. Green CDs, derived from natural sources such as fruits and vegetables, present advantages over conventionally produced CDs, such as cost-effectiveness, stability, simplicity, safety, and environmental friendliness. Various methods, including hydrothermal and microwave treatments, are used to synthesize green CDs, which demonstrate strong biocompatibility, stability, and luminescence. These properties give green CDs versatility in their biological applications, such as bioimaging, biosensing, and drug delivery. This review summarizes the prevalent synthesis methods and renewable sources regarding green CDs; examines their optical features; and explores their extensive biological applications, including in bioimaging, biosensing, drug/gene delivery, antimicrobial and antiviral effects, formatting of mathematical components, cancer diagnosis, and pharmaceutical formulations. Full article

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13 pages, 4081 KiB

Open AccessArticle

S/N Co-Doped Ultrathin TiO₂ Nanoplates as an Anode Material for Advanced Sodium-Ion Hybrid Capacitors

by Yuzhu Li, Qing Lan, Yuanfei Gao, Dan Zhang, Guangyin Liu and Jinbing Cheng

Molecules 2024, 29(18), 4507; https://doi.org/10.3390/molecules29184507 - 23 Sep 2024

Abstract

Anatase titanium dioxide (TiO₂) has emerged as a potential anode material for sodium-ion hybrid capacitors (SICs) in terms of its nontoxicity, high structure stability and cost-effectiveness. However, its inherent poor electrical conductivity and limited reversible capacity greatly hinder its practical application. [...] Read more.

Anatase titanium dioxide (TiO₂) has emerged as a potential anode material for sodium-ion hybrid capacitors (SICs) in terms of its nontoxicity, high structure stability and cost-effectiveness. However, its inherent poor electrical conductivity and limited reversible capacity greatly hinder its practical application. Here, ultrathin TiO₂ nanoplates were synthesized utilizing a hydrothermal technique. The electrochemical kinetics and reversible capacity were significantly improved through sulfur and nitrogen co-doping combined with carbon coating (SN-TiO₂/C). Sulfur and nitrogen co-doping generated oxygen vacancies and introduced additional active sites within TiO₂, facilitating accelerated Na-ion diffusion and enhancing its reversible capacity. Furthermore, carbon coating provided stable support for electron transfer in SN-TiO₂/C during repeated cycling. This synergistic strategy of sulfur and nitrogen co-doping with carbon coating for TiO₂ led to a remarkable capacity of 335.3 mAh g⁻¹ at 0.1 A g⁻¹, exceptional rate property of 148.3 mAh g⁻¹ at 15 A g⁻¹ and a robust cycling capacity. Thus, the SN-TiO₂/C//AC SIC delivered an impressive energy density of 177.9 W h kg⁻¹. This work proposes an idea for the enhancement of reaction kinetics for energy storage materials through a synergistic strategy. Full article

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53 pages, 3040 KiB

Open AccessReview

Recent Progress on Low-Temperature Selective Catalytic Reduction of NO_x with Ammonia

by Eun Duck Park

Molecules 2024, 29(18), 4506; https://doi.org/10.3390/molecules29184506 - 23 Sep 2024

Abstract

Selective catalytic reduction of nitrogen oxides (NO_x) with ammonia (NH₃-SCR) has been implemented in response to the regulation of NO_x emissions from stationary and mobile sources above 300 °C. However, the development of NH₃-SCR catalysts active [...] Read more.

Selective catalytic reduction of nitrogen oxides (NO_x) with ammonia (NH₃-SCR) has been implemented in response to the regulation of NO_x emissions from stationary and mobile sources above 300 °C. However, the development of NH₃-SCR catalysts active at low temperatures below 200 °C is still needed to improve the energy efficiency and to cope with various fuels. In this review article, recent reports on low-temperature NH₃-SCR catalysts are systematically summarized. The redox property as well as the surface acidity are two main factors that affect the catalytic activity. The strong redox property is beneficial for the low-temperature NH₃-SCR activity but is responsible for N₂O formation. The multiple electron transfer system is more plausible for controlling redox properties. H₂O and SO_x, which are often found with NO_x in flue gas, have a detrimental effect on NH₃-SCR activity, especially at low temperatures. The competitive adsorption of H₂O can be minimized by enhancing the hydrophobic property of the catalyst. Various strategies to improve the resistance to SO_x poisoning are also discussed. Full article

(This article belongs to the Section Green Chemistry)

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14 pages, 1320 KiB

Open AccessArticle

Development of a Simple and Validated LC–MS/MS Method for Quantitative Determination of Ketotifen in Beagle Dog Plasma and Its Application to Bioequivalence Study of Ketotifen Syrup Dosage Form

by Eunseo Song, Wang-Seob Shim, Doowon Choi, Yuna Song, Hyeong Geun Jo, Soobok Lee, Suk Han Jung, Yeo Jin Choi and Kyung-Tae Lee

Molecules 2024, 29(18), 4505; https://doi.org/10.3390/molecules29184505 - 23 Sep 2024

Abstract

A highly accurate, precise, and simple liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for ketotifen (KTF) estimation from Beagle dog plasma was developed and validated, with ketotifen-d3 (KTF-d3) as the internal standard (IS). KTF and IS were detected on an API 4000 mass spectrometer [...] Read more.

A highly accurate, precise, and simple liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for ketotifen (KTF) estimation from Beagle dog plasma was developed and validated, with ketotifen-d3 (KTF-d3) as the internal standard (IS). KTF and IS were detected on an API 4000 mass spectrometer in multiple reaction monitoring (MRM) mode in electrospray ionization (ESI) positive ionization mode. The transitions were monitored at m/z 310.2 → 96.0 for KTF and m/z 313.2 → 99.1 for IS. KTF and IS were extracted from plasma using liquid-liquid extraction with methyl tertiary-butyl ether and then analyzed for 3 min with extracted samples (7 µL) into the LC–MS/MS system. Analytes were separated on a Luna^® Hilic column (50 × 2.0 mm i.d., 3 μm) using the Nexera X2 HPLC. The mobile phase A consisted of 10 mmol/L ammonium formate (pH 3.0), while mobile phase B consisted of 0.05% formic acid in acetonitrile. The ratio of mobile phase was 5:95 (v/v) at a flow rate of 0.2 mL/min. The method has been thoroughly validated in accordance with the bioanalytical method validation guidelines established by the Ministry of Food and Drug Safety in Korea and the U.S. Food and Drug Administration, addressing selectivity, lower limit of quantification, linearity, carryover, precision, accuracy, recovery, matrix effect, and stability. The developed LC–MS/MS method was effectively utilized for the bioequivalence assessment of ketotifen in Beagle dog plasma following the oral administration of ketotifen syrup. Full article

(This article belongs to the Special Issue Advanced Analytical Tools for Characterization and Quality Control of Food, Drugs, and Natural Active Ingredients, 2nd Edition)

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14 pages, 5879 KiB

Open AccessArticle

Effect of Pretreatment of Activated Carbon on Iron Oxide-Loaded Catalysts to Significantly Enhance Production of Sebacic Acid from Castor Oil

by Qingyun Zhang, Zhulin Wang, Zhichao Qin, Binglin Li and Zisheng Guo

Molecules 2024, 29(18), 4504; https://doi.org/10.3390/molecules29184504 - 23 Sep 2024

Abstract

This study explores the efficient conversion of castor oil to sebacic acid utilizing iron oxide (Fe₂O₃) loaded on activated carbons as catalysts. Through a combination of saponification, acidification, and catalytic cracking, sebacic acid was produced with a notable yield [...] Read more.

This study explores the efficient conversion of castor oil to sebacic acid utilizing iron oxide (Fe₂O₃) loaded on activated carbons as catalysts. Through a combination of saponification, acidification, and catalytic cracking, sebacic acid was produced with a notable yield improvement. The process involved using liquid paraffin as a thinning agent, overcoming the limitations of traditional toxic agents. The catalysts were prepared via adsorption-precipitation-calcination methods, with ultrasonication pretreatment to enhance iron adsorption on activated carbons. The chemical composition, structure, and morphology properties were investigated by different characterizations; such as scanning electron microscopy (SEM), thermogravimetric analysis (TG/DTG). Systematic investigations into the adsorption capacity, catalytic activity, and operational parameters like temperature, reaction time, and catalyst recycling were conducted. The optimized method achieved a sebacic acid yield of 83.4%, significantly higher than traditional methods (60.2%), with improved safety and environmental impact. The study provides valuable insights into sustainable and efficient sebacic acid production which is crucial for industrial applications in processing of castor oil. Full article

(This article belongs to the Topic Catalysis: Homogeneous and Heterogeneous, 2nd Edition)

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28 pages, 10685 KiB

Open AccessArticle

Structural Optimization of Isoquinoline Derivatives from Lycobetaine and Their Inhibitory Activity against Neuroendocrine Prostate Cancer Cells

by Zhuo Zhang, Qianqian Shen, Yiyi Ji, Yanjie Ma, Haiyang Hou, Huajie Yang, Yinjie Zhu, Yi Chen and Youhong Hu

Molecules 2024, 29(18), 4503; https://doi.org/10.3390/molecules29184503 - 23 Sep 2024

Abstract

Neuroendocrine prostate cancer (NEPC) is a highly aggressive cancer that is resistant to hormone therapy and characterized by poor prognosis, as well as limited therapeutic options. Since the natural product lycobetaine was reported to exhibit good antitumor activities against various types of cancers, [...] Read more.

Neuroendocrine prostate cancer (NEPC) is a highly aggressive cancer that is resistant to hormone therapy and characterized by poor prognosis, as well as limited therapeutic options. Since the natural product lycobetaine was reported to exhibit good antitumor activities against various types of cancers, we initially simplified the scaffold of lycobetaine to obtain the active compound 1, an isoquinoline derivative with an aryl moiety substitution at the 4-position, which showed apparent antiproliferative activities against NPEC cell line LASCPC-01 in vitro. Subsequently, we carried out structural optimization and systematic structure–activity relationship (SAR) studies on compound 1, leading to the discovery of compound 46, which demonstrated potent inhibitory activities against the LASCPC-01 cell line with an IC₅₀ value of 0.47 μM. Moreover, compound 46 displayed remarkable selectivity over prostate cancer cell line PC-3 with a selectivity index greater than 190-fold. Further cell-based mechanism studies revealed that compound 46 and lycobetaine can effectively induce G1 cell cycle arrest and apoptosis dose dependently. However, lycobetaine inhibited the expression of neuroendocrine markers, while compound 46 slightly upregulated these proteins. This suggested that compound 46 might exert its antitumor activities through a different mechanism than lycobetaine, warranting further study. Full article

(This article belongs to the Collection Efficient Pharmaceutical and Chemical Approaches for Anticancer Therapy: Design, Preliminary Evaluations, and Further Developments)

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16 pages, 3792 KiB

Open AccessArticle

A Study of Differential Topology on the Magnetically Induced Isotropically Averaged Lorentz Force Density of a Few Simple Molecules

by Michele Orza, Francesco F. Summa, Riccardo Zanasi and Guglielmo Monaco

Molecules 2024, 29(18), 4502; https://doi.org/10.3390/molecules29184502 - 23 Sep 2024

Abstract

Quantum chemical topology addresses the study of the chemical structure by applying the tools of differential topology to scalar and vector fields obtained by quantum mechanics. Here, the magnetically induced isotropically averaged Lorentz force density was computed and topologically analyzed for 11 small [...] Read more.

Quantum chemical topology addresses the study of the chemical structure by applying the tools of differential topology to scalar and vector fields obtained by quantum mechanics. Here, the magnetically induced isotropically averaged Lorentz force density was computed and topologically analyzed for 11 small molecules. Critical points (attractors, repellers, and saddles) were determined and trajectories connecting the attractors computed. It is shown that kinds and numbers of the critical points are to some extent transferable in similar molecules. CC bonds of different orders are endowed with critical points of different kinds close to their center. The sum of topological indices of the isolated critical points is influenced by the presence of repellers on the outer part of the molecules. Full article

(This article belongs to the Special Issue Feature Papers in Computational and Theoretical Chemistry)

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15 pages, 4220 KiB

Open AccessArticle

Exploring Quinazoline Nitro-Derivatives as Potential Antichagasic Agents: Synthesis and In Vitro Evaluation

by Citlali Vázquez, Audifás-Salvador Matus-Meza, Oswaldo Nuñez-Moreno, Brenda Michelle Barbosa-Sánchez, Victor Manuel Farías-Gutiérrez, Mariana Mendoza-Conde, Francisco Hernández-Luis and Emma Saavedra

Molecules 2024, 29(18), 4501; https://doi.org/10.3390/molecules29184501 - 23 Sep 2024

Abstract

Trypanosoma cruzi is a protozoan parasite that causes Chagas disease in humans. The current antichagasic drugs nifurtimox and benznidazole have inconveniences of toxicity; therefore, the search for alternative therapeutic strategies is necessary. The present study reports the synthesis, drug-likeness predictions, and in vitro [...] Read more.

Trypanosoma cruzi is a protozoan parasite that causes Chagas disease in humans. The current antichagasic drugs nifurtimox and benznidazole have inconveniences of toxicity; therefore, the search for alternative therapeutic strategies is necessary. The present study reports the synthesis, drug-likeness predictions, and in vitro anti-trypanosome activity of a series of 14 quinazoline 2,4,6-triamine derivatives. All compounds were tested against T. cruzi (epimastigotes and trypomastigotes) and in HFF1 human foreskin fibroblasts. The bioassays showed that compounds 2–4 containing nitrobenzoyl substituents at 6-position of the quinazoline 2,4,6-triamine nucleus were the most potent on its antiprotozoal activity. The effect was observed at 24 h and it was preserved for at least 5 days. Also, compounds 2–4 were not toxic to the human control cells, showing high selectivity index. The quinazoline nitro derivatives have potential use as antichagasic agents. Full article

(This article belongs to the Special Issue Design, Synthesis and Biological Evaluation of Medicinal Potential Compounds)

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22 pages, 10758 KiB

Open AccessArticle

Molecular Simulation of the Water Diffusion Behavior and Electronic Properties of Boron-Nitride-Composited Mineral Oil

by Yang Wang, Wenchao Yan, Kunqi Cui, Chuanhui Cheng, Yuanyang Ren and Kai Wu

Molecules 2024, 29(18), 4500; https://doi.org/10.3390/molecules29184500 - 22 Sep 2024

Abstract

Despite the fact that doping nanoparticles into insulating transformer oil has proven to be an effective method of enhancing its dielectric and electrical properties, it remains unclear how different types and surface conditions of nanoparticles may affect their dielectric and electrical properties. Therefore, [...] Read more.

Despite the fact that doping nanoparticles into insulating transformer oil has proven to be an effective method of enhancing its dielectric and electrical properties, it remains unclear how different types and surface conditions of nanoparticles may affect their dielectric and electrical properties. Therefore, the effect of doping various types of BN nanoparticles (nanosphere, nanotube, and nanosheet) in insulating mineral oil (MO) on the diffusion properties of water molecules and electrical properties across the BN/MO interface was investigated using molecular dynamics (MD) and Density Functional Theory (DFT) simulations. Our results show that different surface morphology and grafted functional groups in different types of BN nanoparticles have a significant impact both on the water diffusion behavior and the interfacial potential barrier across the interface between BN and MO. In the MO system directly doped by BN nanospheres, water diffusion behavior is not significantly restricted. However, grafting -NH₂ polar groups onto the BN nanoparticle surface may significantly limit the diffusion behavior of water due to the strong attraction between the -NH₂ polar groups and water molecules; the most significant effect is with nanospheres, followed by nanotubes and nanosheets. In terms of electrical properties across the interface between BN and MO, the h-BN surface (derived from BN nanosheets and nanotubes) acts as a trap for electrons in MO (−0.59 eV), while the c-BN surface (derived from BN nanospheres) acts as a potential barrier for electrons in MO (1.45 eV), and it is noteworthy that the presence of water molecules near the interface between BN and MO has little impact on the potential barriers. Advancing a fundamental understanding of the electrical and water diffusion properties of MO in correlation with the surface morphology of different types of nanoparticles is key to improving the insulation properties of oil-impregnated power transformers. Full article

(This article belongs to the Special Issue Computational and Theoretical Insights on Molecular Structure, Solvation, Interactions and New Materials Design)

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18 pages, 20666 KiB

Open AccessArticle

Comprehensive Investigation into the Impact of Degradation of Recycled Polyethylene and Recycled Polypropylene on the Thermo-Mechanical Characteristics and Thermal Stability of Blends

by Wencai Zhang, Jun Shen, Xiaogang Guo, Ke Wang, Jun Jia, Junting Zhao and Jinshuai Zhang

Molecules 2024, 29(18), 4499; https://doi.org/10.3390/molecules29184499 - 22 Sep 2024

Abstract

The impact of degradation on plastics is a critical factor influencing their properties and behavior, particularly evident in polyethylene (PE) and polypropylene (PP) and their blends. However, the effect of photoaging and thermal degradation, specifically within recycled polyethylene (rPE) and recycled polypropylene (rPP), [...] Read more.

The impact of degradation on plastics is a critical factor influencing their properties and behavior, particularly evident in polyethylene (PE) and polypropylene (PP) and their blends. However, the effect of photoaging and thermal degradation, specifically within recycled polyethylene (rPE) and recycled polypropylene (rPP), on the thermo-mechanical and thermostability aspects of these blends remains unexplored. To address this gap, a range of materials, including virgin polyethylene (vPE), recycled polyethylene (rPE), virgin polypropylene (vPP), recycled polypropylene (rPP), and their blends with different ratios, were comprehensively investigated. Through a systematic assessment encompassing variables such as melting flow index (MFI), functional groups, mechanical traits, crystallization behavior, microscopic morphology, and thermostability, it was found that thermo-oxidative degradation generated hydroxyl and carboxyl functional groups in rPE and rPP. Optimal mechanical properties were achieved with a 6:4 mass ratio of rPE to rPP, as validated by FTIR spectroscopy and microscopic morphology. By establishing the chemical model, the changes in the system with an rPE–rPP ratio of 6:4 and 8:2 were monitored by the molecular simulation method. When the rPE–rPP ratio was 6:4, the system’s energy was lower, and the number of hydrogen bonds was higher, which also confirmed the above experimental results. Differential scanning calorimetry revealed an increased crystallization temperature in rPE, a reduced crystallization peak area in rPP, and a diminished crystallization capacity in rPE/rPP blends, with rPP exerting a pronounced influence. This study plays a pivotal role in enhancing recycling efficiency and reducing production costs for waste plastics, especially rPE and rPP—the primary components of plastic waste. By uncovering insights into the degradation effects and material behaviors, our research offers practical pathways for more sustainable waste management. This approach facilitates the optimal utilization of the respective performance characteristics of rPE and rPP, enabling the development of highly cost-effective rPE/rPP blend materials and promoting the efficient reuse of waste materials. Full article

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17 pages, 1924 KiB

Open AccessArticle

Pharmacokinetics and Dose Proportionality Study of a Novel Antiparkinsonian Agent, a 1H-1,2,4-Triazol-3-ylthio-conjugate of Prottremine

by Daria S. Gorina, Anastasiya V. Lastovka, Artem D. Rogachev, Alexandra V. Podturkina, Alla V. Pavlova, Oleg V. Ardashov, Nikolai S. Li-Zhulanov, Tatyana G. Tolstikova, Konstantin P. Volcho and Nariman F. Salakhutdinov

Molecules 2024, 29(18), 4498; https://doi.org/10.3390/molecules29184498 - 22 Sep 2024

Abstract

The novel antiparkinsonian agent PA-96 is the focus of our research. PA-96 supported the survival of cultured naïve dopamine neurons, alleviated motor deficits in MPTP and haloperidol-based mice models of Parkinson’s disease, and increased the density of tyrosine hydroxylase positive neurons and dopamine [...] Read more.

The novel antiparkinsonian agent PA-96 is the focus of our research. PA-96 supported the survival of cultured naïve dopamine neurons, alleviated motor deficits in MPTP and haloperidol-based mice models of Parkinson’s disease, and increased the density of tyrosine hydroxylase positive neurons and dopamine concentration in the midbrain of an MPTP-damaged brain. In this work, an HPLC–MS/MS method was developed and validated, and the pharmacokinetics of the agent was investigated in mice after a single or multiple oral administration (p.o.) and intravenous injection (i.v.) at various doses. The dose proportionality was also evaluated after a single p.o. administration of three ascending doses (1, 5, and 10 mg/kg) and a single i.v. injection of two doses (1 and 10 mg/kg); also, the bioavailability was estimated. The disproportionality of pharmacokinetic parameters could be explained by the saturation of active centres of enzymes or receptors binding the substance: at low doses, part of the compound is bound, leaving a small amount circulating in blood, and rapidly metabolised and/or bound too. The bioavailability of PA-96 was c.a. 7 and 35% for the doses of 5 and 10 mg/kg, correspondingly. Full article

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20 pages, 5975 KiB

Open AccessArticle

Dynamic Adsorption of Mn²⁺ from Acid Mine Drainage by Highly Active Immobilized Particles with Fe⁰/Fe²⁺ Enhanced SRB

by He Chen, Laigui Wang, Wenbo An and Qiqi Wang

Molecules 2024, 29(18), 4497; https://doi.org/10.3390/molecules29184497 - 22 Sep 2024

Abstract

Bioremediation of acid mine drainage (AMD) was often challenged by poor tolerance of sulfate-reducing bacteria (SRB) to heavy metals and low bioactivity. The highly active immobilized particles with Fe⁰/Fe²⁺ enhanced SRB (Fe^0/2+-SRB) were prepared by the microorganism immobilization [...] Read more.

Bioremediation of acid mine drainage (AMD) was often challenged by poor tolerance of sulfate-reducing bacteria (SRB) to heavy metals and low bioactivity. The highly active immobilized particles with Fe⁰/Fe²⁺ enhanced SRB (Fe^0/2+-SRB) were prepared by the microorganism immobilization technique. Three dynamic columns were constructed to investigate the adsorption capacity of Fe^0/2+-SRB for Mn²⁺ under varying adsorption layer heights, inflow velocity, and initial Mn²⁺ concentrations. The role of each matrix material in the immobilized particles was explored, the mechanism of AMD remediation by Fe^0/2+-SRB was revealed, and the adaptability of Fe^0/2+-SRB to AMD under various initial conditions was investigated. The results showed that the prepared Fe^0/2+-SRB exhibited a well-developed surface pore structure. When the adsorption layer height was 200 mm, the influent flow rate was 5 × 10⁻⁵ m³/s, and the initial manganese ion concentration was 10 mg/L, the maximum dynamic adsorption capacities (q_e) of Mn²⁺ for each dynamic column were 7.8430, 4.7627, and 8.7677 mg/g, respectively. Compared to dynamic columns 1# and 2#, dynamic column 3# showed the best performance in treating AMD, and the Thomas model effectively described the adsorption kinetics of Mn²⁺ by Fe^0/2+-SRB(3#). Microstructural analysis indicated that chemical adsorption, ion exchange, dissimilation–reduction reaction, and surface complexation occurred between the various matrix materials in Fe^0/2+-SRB(3#). Mn²⁺ was primarily removed in the form of metal sulfide (MnS), and Fe⁰/Fe²⁺ could promote the dissimilatory reduction of SO₄²⁻ by SRB to form S²⁻. Fe^0/2+-SRB(3#) was able to adapt to AMD with initial conditions of pH was 2~4, SO₄²⁻ < 2500 mg/L, and Mn²⁺ < 20 mg/L. The research results provide new insights into the remediation of AMD, using a combined microbial-adsorption technology. Full article

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15 pages, 1610 KiB

Open AccessArticle

Linear and Angular Heteroannulated Pyridines Tethered 6-Hydroxy-4,7-Dimethoxybenzofuran: Synthesis and Antimicrobial Activity

by Najla A. Alshaye, Al-Shimaa Badran and Magdy A. Ibrahim

Molecules 2024, 29(18), 4496; https://doi.org/10.3390/molecules29184496 - 22 Sep 2024

Abstract

2-Chloropyridine-3-carbonitrile derivative 1 was utilized as a key precursor to build a series of linear and angular annulated pyridines linked to a 6-hydroxy-4,7-dimethoxybenzofuran moiety. Reaction of substrate 1 with various hydrazines afforded pyrazolo[3,4-b]pyridines. Treatment of substrate 1 with 1,3-N, [...] Read more.

2-Chloropyridine-3-carbonitrile derivative 1 was utilized as a key precursor to build a series of linear and angular annulated pyridines linked to a 6-hydroxy-4,7-dimethoxybenzofuran moiety. Reaction of substrate 1 with various hydrazines afforded pyrazolo[3,4-b]pyridines. Treatment of substrate 1 with 1,3-N,N-binucleophiles including 3-amino-1,2,4-triazole, 5-amino-1H-tetrazole, 3-amino-6-methyl-1,2,4-triazin-5(4H)-one and 2-aminobenzimidazole produced the novel angular pyrido[3,2-e][1,2,4]triazolo[4,3-a]pyrimidine, pyrido[3,2-e][1,2,4]tetrazolo[1,5-a]pyrimidine, pyrido[3′,2′:5,6] pyrimido[2,1-c][1,2,4]triazine and benzo[4,5]imidazo[1,2-a]pyrido[3,2-e]pyrimidine, respectively. Reaction of substrate 1 with 1,3-C,N-binucleophiles including cyanoacetamides and 1H-benzimidazol-2-ylacetonitrile furnished 1,8-naphthyridines and benzoimidazonaphthyridine. Moreover, reacting substrate 1 with 5-aminopyrazoles gave pyrazolo[3,4-b][1,8]naphthyridines. Finally, reaction of compound 1 with 6-aminouracils as cyclic enamines yielded pyrimido[4,5-b][1,8]naphthyridines. Some of the synthesized products showed noteworthy antimicrobial efficiency against all types of microbial strains. Structures of the produced compounds were established using analytical and spectroscopic tools. Full article

(This article belongs to the Special Issue Synthetic Studies Aimed at Heterocyclic Organic Compounds)

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16 pages, 5685 KiB

Open AccessArticle

A Dy(III) Coordination Polymer Material as a Dual-Functional Fluorescent Sensor for the Selective Detection of Inorganic Pollutants

by Ying Wang, Baigang An, Si Li, Lijiang Chen, Lin Tao, Timing Fang and Lei Guan

Molecules 2024, 29(18), 4495; https://doi.org/10.3390/molecules29184495 - 22 Sep 2024

Abstract

A Dy(III) coordination polymer (CP), [Dy(spasds)(H₂O)₂]_n (1) (Na₂Hspasds = 5-(4-sulfophenylazo)salicylic disodium salt), has been synthesized using a hydrothermal method and characterized. 1 features a 2D layered structure, where the spasda³⁻ anions act as [...] Read more.

A Dy(III) coordination polymer (CP), [Dy(spasds)(H₂O)₂]_n (1) (Na₂Hspasds = 5-(4-sulfophenylazo)salicylic disodium salt), has been synthesized using a hydrothermal method and characterized. 1 features a 2D layered structure, where the spasda³⁻ anions act as pentadentate ligands, adopting carboxylate, sulfonate and phenolate groups to bridge with four Dy centers in η₃-μ¹: μ², η₂-μ¹: μ¹, and monodentate coordination modes, respectively. It possesses a unique (4,4)-connected net with a Schläfli symbol of {4⁴·6²}{4}₂. The luminescence study revealed that 1 exhibited a broad fluorescent emission band at 392 nm. Moreover, the visual blue color has been confirmed by the CIE plot. 1 can serve as a dual-functional luminescent sensor toward Fe³⁺ and MnO₄⁻ through the luminescence quenching effect, with limits of detection (LODs) of 9.30 × 10⁻⁷ and 1.19 × 10⁻⁶ M, respectively. The LODs are relatively low in comparison with those of the reported CP-based sensors for Fe³⁺ and MnO₄⁻. In addition, 1 also has high selectivity and remarkable anti-interference ability, as well as good recyclability for at least five cycles. Furthermore, the potential application of the sensor for the detection of Fe³⁺ and MnO₄⁻ was studied through simulated wastewater samples with different concentrations. The possible sensing mechanisms were investigated using Ultraviolet-Visible (UV-Vis) absorption spectroscopy and density functional theory (DFT) calculations. The results revealed that the luminescence turn-off effects toward Fe³⁺ and MnO₄⁻ were caused by competitive absorption and photoinduced electron transfer (PET), and competitive absorption and inner filter effect (IFE), respectively. Full article

(This article belongs to the Special Issue Synthesis, Structural Analysis, and Applications of N,O-donor Ligands and Their Coordination Polymers)

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13 pages, 7465 KiB

Open AccessArticle

Unveiling the Dynamic Evolution of Catalytic Sites in N-Doped Leaf-like Carbon Frames Embedded with Co Particles for Rechargeable Zn–Air Batteries

by Yuebin Lian, Weilong Xu, Xiaojiao Du, Yannan Zhang, Weibai Bian, Yuan Liu, Jin Xiao, Likun Xiong and Jirong Bai

Molecules 2024, 29(18), 4494; https://doi.org/10.3390/molecules29184494 - 22 Sep 2024

Abstract

The advancement of cost-effective, high-performance catalysts for both electrochemical oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) is crucial for the widespread implementation of metal–air batteries. In this research, we fabricated leaf-like N-doped carbon frames embedded with Co nanoparticles by pyrolyzing a [...] Read more.

The advancement of cost-effective, high-performance catalysts for both electrochemical oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) is crucial for the widespread implementation of metal–air batteries. In this research, we fabricated leaf-like N-doped carbon frames embedded with Co nanoparticles by pyrolyzing a ZIF-L/carbon nanofiber (ZIF-L/CNF) composite. Consequently, the optimized ZIF-L/CNF-700 catalyst exhibit exceptional catalytic activities in both ORRs and OERs, comparable to the benchmark 20 wt% Pt/C and RuO₂. Addressing the issue of diminished cycle performance in the Zn–air battery cycle process, further detailed investigations into the post-electrolytic composition reveal that both the carbon framework and Co nanoparticles undergo partial oxidation during both OERs and ORRs. Owing to the varying local pH on the catalyst surface due to the consumption and generation of OH⁻ by OERs and ORRs, after OERs, the product is reduced-size Co particles, while after ORRs, the product is outer-layer Co(OH)₂-enveloping Co particles. Full article

(This article belongs to the Special Issue Advanced Electrode Materials for Electrochemical Energy Storage and Conversion, 2nd Edition)

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18 pages, 3884 KiB

Open AccessArticle

Towards Nickel–NHC Fluoro Complexes—Synthesis of Imidazolium Fluorides and Their Reactions with Nickelocene

by Siobhan S. Wills, Corinne Bailly and Michael J. Chetcuti

Molecules 2024, 29(18), 4493; https://doi.org/10.3390/molecules29184493 - 21 Sep 2024

Abstract

While hundreds of complexes of the general formula [Ni(η⁵-C₅H₅)(NHC)(X)] exist (NHC = a N-heterocyclic carbene, X = Cl, Br, I), none is yet known with X = F. We attempted to prepare such a species by reacting [...] Read more.

While hundreds of complexes of the general formula [Ni(η⁵-C₅H₅)(NHC)(X)] exist (NHC = a N-heterocyclic carbene, X = Cl, Br, I), none is yet known with X = F. We attempted to prepare such a species by reacting nickelocene with imidazolium fluorides. Three imidazolium fluorides (ImH)⁺ F⁻ [Im = (N,N′-bis-(R)-imidazolium: 1a, IMe, R = Me; 1b, IMes, R = 2,4,6-trimethylphenyl; 1c, IPr, R = 2,6-diisopropylphenyl)] were prepared and characterized by spectroscopic methods. In addition, the salts 1b [(IMesH)⁺ F⁻] and 1c [(IPrH)⁺ F⁻] were subjected single-crystal X-ray diffraction experiments. The reactions of these imidazolium fluorides with nickelocene did not lead to [Ni(η⁵-C₅H₅)(NHC)(F)] species. Instead, the reaction of 1a [(IMeH)⁺ F⁻] and 1b [(IMesH)⁺ F⁻] with nickelocene led to the salt 2 [Ni(η⁵-C₅H₅)(IMe)₂]⁺ F⁻ and to the square planar complex 3atrans-[NiF₂(IMes)₂] respectively. Both complexes were characterized spectroscopically and by single crystal X-ray diffraction. All four X-ray diffraction studies reveal hydrogen bonding and hydrogen interactions with the F atom or anion, and in some cases with solvent molecules of crystallization, and these phenomena are all discussed. Complex 2, in particular, exhibited a wide range of interesting H-bonded interactions in the solid state. Complexes 2 and 3a were tested as catalysts for Suzuki–Miyaura coupling but were not promising: complex 2 was inactive, and while 3a did indeed catalyze the reaction, it gave widely diverging results owing to its instability in solution. Full article

(This article belongs to the Special Issue Advances in Coordination Chemistry 2.0)

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13 pages, 3521 KiB

Open AccessArticle

Ni–Doped Pr_0.7Ba_0.3MnO_3−δ Cathodes for Enhancing Electrolysis of CO₂ in Solid Oxide Electrolytic Cells

by Fei Shan, Tao Chen, Lingting Ye and Kui Xie

Molecules 2024, 29(18), 4492; https://doi.org/10.3390/molecules29184492 - 21 Sep 2024

Abstract

Solid Oxide Electrolysis Cells (SOECs) can electro-reduce carbon dioxide to carbon monoxide, which not only effectively utilizes greenhouse gases, but also converts excess electrical energy into chemical energy. Perovskite-based oxides with exsolved metal nanoparticles are promising cathode materials for direct electrocatalytic reduction of [...] Read more.

Solid Oxide Electrolysis Cells (SOECs) can electro-reduce carbon dioxide to carbon monoxide, which not only effectively utilizes greenhouse gases, but also converts excess electrical energy into chemical energy. Perovskite-based oxides with exsolved metal nanoparticles are promising cathode materials for direct electrocatalytic reduction of CO₂ through SOECs, and have thus received increasing attention. In this work, we doped Pr_0.7Ba_0.3MnO_3−δ at the B site, and after reduction treatment, metal nanoparticles exsolved and precipitated on the surface of the cathode material, thereby establishing a stable metal–oxide interface structure and significantly improving the electrocatalytic activity of the SOEC cathode materials. Through research, among the Pr_0.7Ba_0.3Mn_1−xNi_xO_3−δ (PBMN_x = 0–1) cathode materials, it has been found that the Pr_0.7Ba_0.3Mn_0.9Ni_0.1O_3−δ (PBMN_0.1) electrode material exhibits greater catalytic activity, with a CO yield of 5.36 mL min⁻¹ cm⁻² and a Faraday current efficiency of ~99%. After 100 h of long-term testing, the current can still remain stable and there is no significant change in performance. Therefore, the design of this interface has increasing potential for development. Full article

(This article belongs to the Special Issue Electrochemical Energy Conversion and Potential Strategies in Electrochemical Energy Storage)

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9 pages, 1113 KiB

Open AccessCommunication

Chemical Derivatization and Paper Spray Ionization Mass Spectrometry for Fast Screening of Retinoic Acid in Cosmetics

by Yuzhang Bao, Ningzi Guo, Xiaowen Hu, Bin Di, Yang Liu and Huimin Sun

Molecules 2024, 29(18), 4491; https://doi.org/10.3390/molecules29184491 - 21 Sep 2024

Abstract

As a prescription drug, retinoic acid is listed as a banned cosmetic additive in the EU and China regulations. Currently, spectrophotometric methods, including thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and HPLC–MS/MS, are commonly used for the determination of retinoic acid. As these [...] Read more.

As a prescription drug, retinoic acid is listed as a banned cosmetic additive in the EU and China regulations. Currently, spectrophotometric methods, including thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and HPLC–MS/MS, are commonly used for the determination of retinoic acid. As these conventional methods require complex pretreatment and are time-consuming, chemical derivatization combined with paper spray ionization mass spectrometry was developed for the fast detection of retinoic acid in cosmetics. N,N-dimethylpiperazine iodide (DMPI) was utilized as a derivatization reagent. Carboxylic acid in retinoic acid was derivatized to carry a positive charge and was subjected to mass spectrometry analysis. Results showed that compared with non-derivatized compounds, the detection limit was increased by about 50 times. The linearity in the range of 0.005–1 μg·mL⁻¹ was good. The limit of detection (LOD) was 0.0013 μg·mL⁻¹, and the limit of quantification (LOQ) was 0.0043 μg·mL⁻¹. The recoveries of spiked samples were in the range of 95–105%, and the RSDs were below 5%. Derivatization and paper spray ionization MS render a quick, sensitive, and accurate method for the detection of retinoic acid in a complex matrix. Full article

(This article belongs to the Section Analytical Chemistry)

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10 pages, 3461 KiB

Open AccessArticle

A Fluorescence Enhancement Sensor Based on Silver Nanoclusters Protected by Rich-G-DNA for ATP Detection

by Yuxia Li, Jingxuan Ren, Zeting Meng and Baozhu Zhang

Molecules 2024, 29(18), 4490; https://doi.org/10.3390/molecules29184490 - 21 Sep 2024

Abstract

In this study, a turn-on fluorescence sensor for the detection of adenosine 5′-triphosphate (ATP) was developed and tested using ATP-DNA2-Ag NCs. The results showed that the fluorescence of ATP-DNA2-Ag NCs was significantly enhanced with the addition of ATP. The fluorescence enhancement was a [...] Read more.

In this study, a turn-on fluorescence sensor for the detection of adenosine 5′-triphosphate (ATP) was developed and tested using ATP-DNA2-Ag NCs. The results showed that the fluorescence of ATP-DNA2-Ag NCs was significantly enhanced with the addition of ATP. The fluorescence enhancement was a result of the specific binding activity of the ATP aptamer and ATP, which caused G-rich sequences to approach the dark DNA-Ag NCs, owing to the alteration in ATP aptamer conformation. The proposed sensor demonstrated a good linear range of 18–42 mM and a limit of detection (LOD) of 2.8 μM. The sensor’s features include sensitivity, selectivity, and simple operation. In addition, the proposed sensor successfully measured ATP in 100-fold diluted fetal bovine serum. Full article

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14 pages, 1801 KiB

Open AccessArticle

Strength of London Dispersion Forces in Organic Structure Directing Agent—Zeolite Assemblies

by Karima Ata, Tzonka Mineva and Bruno Alonso

Molecules 2024, 29(18), 4489; https://doi.org/10.3390/molecules29184489 - 21 Sep 2024

Abstract

Herein, we study the London dispersion forces between organic structure directing agents (OSDAs)—here tetraalkyl-ammonium or -phosphonium molecules—and silica zeolite frameworks (FWs). We demonstrate that the interaction energy for these dispersion forces is correlated to the number of H atoms in OSDAs, irrespective of [...] Read more.

Herein, we study the London dispersion forces between organic structure directing agents (OSDAs)—here tetraalkyl-ammonium or -phosphonium molecules—and silica zeolite frameworks (FWs). We demonstrate that the interaction energy for these dispersion forces is correlated to the number of H atoms in OSDAs, irrespective of the structures of OSDAs or FWs, and of variations in charges and thermal motions. All calculations considered—DFT-D3 and BOMD undertaken by us, and molecular mechanics from an accessible database—led to the same trend. The mean energy of these dispersion forces is ca. −2 kcal.mol⁻¹ per H for efficient H-O contacts. Full article

(This article belongs to the Special Issue Advances in Computational and Theoretical Chemistry—2nd Edition)

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18 pages, 3022 KiB

Open AccessArticle

Biosorption Ability of Pharmaceutically Active Compounds by Anabaena sp. and Chroococcidiopsis thermalis

by Jerzy Pogrzeba and Anna Poliwoda

Molecules 2024, 29(18), 4488; https://doi.org/10.3390/molecules29184488 - 21 Sep 2024

Abstract

Drug overuse harms the biosphere, leading to disturbances in ecosystems’ functioning. Consequently, more and more actions are being taken to minimise the harmful impact of xenopharmaceuticals on the environment. One of the innovative solutions is using biosorbents—natural materials such as cells or biopolymers—to [...] Read more.

Drug overuse harms the biosphere, leading to disturbances in ecosystems’ functioning. Consequently, more and more actions are being taken to minimise the harmful impact of xenopharmaceuticals on the environment. One of the innovative solutions is using biosorbents—natural materials such as cells or biopolymers—to remove environmental pollutants; however, this focuses mainly on the removal of metal ions and colourants. Therefore, this study investigated the biosorption ability of selected pharmaceuticals—paracetamol, diclofenac, and ibuprofen—by the biomass of the cyanobacteria Anabaena sp. and Chroococcidiopsis thermalis, using the LC-MS/MS technique. The viability of the cyanobacteria was assessed by determining photosynthetic pigments in cells using a UV–VIS spectrophotometer. The results indicate that both tested species can be effective biosorbents for paracetamol and diclofenac. At the same time, the tested compounds did not have a toxic effect on the tested cyanobacterial species and, in some cases, stimulated their cell growth. Furthermore, the Anabaena sp. can effectively biotransform DCF into its dimer. Full article

(This article belongs to the Special Issue Advanced Analysis of Contaminants of Emerging Concern: Volume II)

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15 pages, 2514 KiB

Open AccessArticle

Synthesis of Novel Planar-Chiral Charge-Compensated nido-Carborane-Based Amino Acid

by Dmitry A. Gruzdev, Angelina A. Telegina, Marina A. Ezhikova, Mikhail I. Kodess, Galina L. Levit and Victor P. Krasnov

Molecules 2024, 29(18), 4487; https://doi.org/10.3390/molecules29184487 - 21 Sep 2024

Abstract

Amino acids with unusual types of chirality and their derivatives have recently attracted attention as precursors in the synthesis of chiral catalysts and peptide analogues with unique properties. In this study, we have synthesized a new nido-carborane-based planar-chiral amino acid, in the [...] Read more.

Amino acids with unusual types of chirality and their derivatives have recently attracted attention as precursors in the synthesis of chiral catalysts and peptide analogues with unique properties. In this study, we have synthesized a new nido-carborane-based planar-chiral amino acid, in the molecule of which the amino group is directly bonded to the B(3) atom, and the carboxyl group is attached to the B(9) atom through the CH₂S⁺(Me) fragment. 3-Amino-9-dimethylsulfonio-nido-carborane, prepared in three steps from 3-amino-closo-carborane in a high yield, was a key intermediate in the synthesis of the target planar-chiral amino acid. The carboxymethyl group at the sulfur atom was introduced by the demethylation reaction of the dimethylsulfonio derivative, followed by S-alkylation. The structure of new 3,9-disubstituted nido-carboranes was studied for the first time using NMR spectroscopy. The resonances of all boron atoms in the ¹¹B NMR spectrum of 3-amino-9-dimethylsulfonio-nido-carborane were assigned based on the 2D NMR correlation experiments. The nido-carborane-based planar-chiral amino acid and related compounds are of interest as a basis for peptide-like compounds and chiral ligands. Full article

(This article belongs to the Special Issue Boron Chemistry and Applications)

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Molecules, Volume 29, Issue 18 (September-2 2024) – 235 articles

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