Molecules

16 pages, 2973 KiB

Open AccessArticle

Acidity Constants of Boronic Acids as Simply as Possible: Experimental, Correlations, and Prediction

by Andrzej Sporzyński, Agnieszka Adamczyk-Woźniak, Dorota Zarzeczańska, Jan T. Gozdalik, Paulina Ramotowska and Wiktoria Abramczyk

Molecules 2024, 29(11), 2713; https://doi.org/10.3390/molecules29112713 - 6 Jun 2024

Viewed by 393

Abstract

The wide use of boronic compounds, especially boronic acids and benzoxaboroles, in virtually all fields of chemistry is related to their specific properties. The most important of them are the ability to form cyclic esters with diols and the complexation of anions. In [...] Read more.

The wide use of boronic compounds, especially boronic acids and benzoxaboroles, in virtually all fields of chemistry is related to their specific properties. The most important of them are the ability to form cyclic esters with diols and the complexation of anions. In both cases, the equilibrium of the reaction depends mainly on the acidity of the compounds, although other factors must also be taken into account. Quantification of the acidity (pK_a value) is a fundamental factor considered when designing new compounds of practical importance. The aim of the current work was to collect available values of the acidity constants of monosubstituted phenylboronic acids, critically evaluate these data, and supplement the database with data for missing compounds. Measurements were made using various methods, as a result of which a fast and reliable method for determining the pK_a of boronic compounds was selected. For an extensive database of monosubstituted phenylboronic acids, their correlation with their Brønsted analogues—namely carboxylic acids—was examined. Compounds with ortho substituents do not show any correlation, which is due to the different natures of both types of acids. Nonetheless, both meta- and para-substituted compounds show excellent correlation. From a practical point of view, acidity constants are best determined from the Hammett equation. Computational approaches for determining acidity constants were also analyzed. In general, the reported calculated values are not compatible with experimental ones, providing comparable results only for selected groups of compounds. Full article

(This article belongs to the Section Physical Chemistry)

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12 pages, 3004 KiB

Open AccessArticle

Evaluation of Aromatic Characteristics and Potential Applications of Hemerocallis L. Based on the Analytic Hierarchy Process

by Yiming Zhou, Wei Yang, Siyi Zhu, Jianan Wei, Xiaoli Zhou, Minglong Wang and Hongxiu Lu

Molecules 2024, 29(11), 2712; https://doi.org/10.3390/molecules29112712 - 6 Jun 2024

Viewed by 336

Abstract

Hemerocallis L. possesses abundant germplasm resources and holds significant value in terms of ornamental, edible, and medicinal aspects. However, the quality characteristics vary significantly depending on different varieties. Selection of a high-quality variety with a characteristic aroma can increase the economic value of [...] Read more.

Hemerocallis L. possesses abundant germplasm resources and holds significant value in terms of ornamental, edible, and medicinal aspects. However, the quality characteristics vary significantly depending on different varieties. Selection of a high-quality variety with a characteristic aroma can increase the economic value of Hemerocallis flowers. The analytic hierarchy process (AHP) is an effective decision-making method for comparing and evaluating multiple characteristic dimensions. By applying AHP, the aromatic character of 60 varieties of Hemerocallis flowers were analyzed and evaluated in the present study. Headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) was employed to identify volatile components in Hemerocallis flowers. Thirteen volatile components were found to contribute to the aroma of Hemerocallis flowers, which helps in assessing their potential applications in essential oil, aromatherapy, and medical treatment. These components include 2-phenylethanol, geraniol, linalool, nonanal, decanal, (E)-β-ocimene, α-farnesene, indole, nerolidol, 3-furanmethanol, 3-carene, benzaldehyde and benzenemethanol. The varieties with better aromatic potential can be selected from a large amount of data using an AHP model. This study provides a comprehensive understanding of the characteristics of the aroma components in Hemerocallis flowers, offers guidance for breeding, and enhances the economic value of Hemerocallis flowers. Full article

(This article belongs to the Special Issue Functional Volatile Compounds: Detection, Analysis and Applications)

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10 pages, 5510 KiB

Open AccessArticle

Molecular Insight into the Processes and Mechanisms of N₂ Adsorption and Accumulation at the Hydrophobic Solid/Liquid Interface

by Bao Li and Dan Su

Molecules 2024, 29(11), 2711; https://doi.org/10.3390/molecules29112711 - 6 Jun 2024

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Abstract

In this study, molecular dynamics (MD) simulations were employed to elucidate the processes and underlying mechanisms that govern the adsorption and accumulation of gas (represented by N₂) at the hydrophobic solid–liquid interface, using the GROMACS program with an AMBER force field. [...] Read more.

In this study, molecular dynamics (MD) simulations were employed to elucidate the processes and underlying mechanisms that govern the adsorption and accumulation of gas (represented by N₂) at the hydrophobic solid–liquid interface, using the GROMACS program with an AMBER force field. Our findings indicate that, regardless of surface roughness, the presence of water molecules is a prerequisite for the adsorption and aggregation of N₂ molecules on solid surfaces. N₂ molecules dissolved in water can cluster even without a solid substrate. In the gas–solid–liquid system, the exclusion of water molecules at the hydrophobic solid–liquid interface and the adsorption of N₂ molecules do not occur simultaneously. A loosely arranged layer of water molecules is initially formed on the hydrophobic solid surface. The two-stage process of N₂ molecule adsorption and accumulation at the hydrophobic solid/liquid interface involves initial adsorption to the solid surface, displacing water molecules, followed by N₂ accumulation via self-interaction after saturating the substrate’s surface. The process and underlying mechanisms of gas adsorption and accumulation at hydrophobic solid/liquid interfaces elucidated in this study offer a molecular-level understanding of nano-gas layer formation. Full article

(This article belongs to the Section Molecular Liquids)

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22 pages, 1325 KiB

Open AccessArticle

Comparing Nutritional Values and Bioactivity of Kefir from Different Types of Animal Milk

by Chiara La Torre, Paolino Caputo, Erika Cione and Alessia Fazio

Molecules 2024, 29(11), 2710; https://doi.org/10.3390/molecules29112710 - 6 Jun 2024

Viewed by 411

Abstract

The growing interest in fermented dairy products is due to their health-promoting properties. The use of milk kefir grains as a starter culture made it possible to obtain a product with a better nutritional and biological profile depending on the type of milk. [...] Read more.

The growing interest in fermented dairy products is due to their health-promoting properties. The use of milk kefir grains as a starter culture made it possible to obtain a product with a better nutritional and biological profile depending on the type of milk. Cow, buffalo, camel, donkey, goat, and sheep milk kefirs were prepared, and the changes in sugar, protein, and phenol content, fatty acid composition, including conjugated linoleic acids (CLAs), as well as antioxidant activity, determined by ABTS and FRAP assays, were evaluated and compared. The protein content of cow, buffalo, donkey, and sheep milk increased after 24 h of fermentation. The fatty acid profile showed a better concentration of saturated and unsaturated lipids in all fermented milks, except buffalo milk. The highest content of beneficial fatty acids, such as oleic, linoleic, and C18:2 conjugated linoleic acid, was found in the cow and sheep samples. All samples showed a better antioxidant capacity, goat milk having the highest value, with no correlation to the total phenolic content, which was highest in the buffalo sample (260.40 ± 5.50 μg GAE/mL). These findings suggested that microorganisms living symbiotically in kefir grains utilize nutrients from different types of milk with varying efficiency. Full article

(This article belongs to the Special Issue New Frontiers in Fermented Products – 2nd Edition)

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17 pages, 2614 KiB

Open AccessArticle

Unique Use of Dibromo–L–Tyrosine Ligand in Building of Cu(II) Coordination Polymer—Experimental and Theoretical Investigations

by Agnieszka Wojciechowska, Jan Janczak, Tomasz Rojek, Muhammad Ashfaq, Magdalena Malik, Natasza Trzęsowska, Rafał Wysokiński and Julia Jezierska

Molecules 2024, 29(11), 2709; https://doi.org/10.3390/molecules29112709 - 6 Jun 2024

Viewed by 402

Abstract

Although the crystals of coordination polymer {[CuCl(μ-O,O’-L-Br₂Tyr)]}n (1) (L-Br₂Tyr = 3,5-dibromo-L-tyrosine) were formed under basic conditions, crystallographic studies revealed that the OH group of the ligand remained protonated. Two adjacent [CuCl(L-Br₂Tyr)] monomers, bridged by the [...] Read more.

Although the crystals of coordination polymer {[CuCl(μ-O,O’-L-Br₂Tyr)]}n (1) (L-Br₂Tyr = 3,5-dibromo-L-tyrosine) were formed under basic conditions, crystallographic studies revealed that the OH group of the ligand remained protonated. Two adjacent [CuCl(L-Br₂Tyr)] monomers, bridged by the carboxylate group of the ligand in the syn-anti bidentate bridging mode, are differently oriented to form a polymeric chain; this specific bridging was detected also by FT-IR and EPR spectroscopy. Each Cu(II) ion in polymeric compound 1 is coordinated in the xy plane by the amino nitrogen and carboxyl oxygen of the parent ligand and the oxygen of the carboxyl group from the symmetry related ligand of the adjacent [Cu(L-Br₂Tyr)Cl] monomer, as well as an independent chlorine ion. In addition, the Cu(II) ion in the polymer chain participates in long-distance intermolecular contacts with the oxygen and bromine atoms of the ligands located in the adjacent chains; these intramolecular contacts were also supported by NCI and NBO quantum chemical calculations and Hirshfeld surface analysis. The resulting elongated octahedral geometry based on the [CuCl(L-Br₂Tyr)] monomer has a lower than axial symmetry, which is also reflected in the symmetry of the calculated molecular EPR g tensor. Consequently, the components of the d-d band obtained by analysis of the NIR-VIS-UV spectrum were assigned to the corresponding electronic transitions. Full article

(This article belongs to the Section Inorganic Chemistry)

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15 pages, 3058 KiB

Open AccessArticle

Visible Light Enhancement of Biocarbon Quantum-Dot-Decorated TiO₂ for Naphthalene Removal

by Yunteng Chen, Chunxian Hong, Qiang Xu, Haihong Zheng, Chao Wang, Hongshun Lu, Shuai Zhang, Mingming Du and Ganning Zeng

Molecules 2024, 29(11), 2708; https://doi.org/10.3390/molecules29112708 - 6 Jun 2024

Viewed by 556

Abstract

In this study, carbon-quantum-dot (CQD)-decorated TiO₂ was prepared using an ultrasonic doping method and applied in the photocatalytic degradation of naphthalene under sunlight irradiation. The CQDs were synthesized from a typical macroalgae via diluted sulfuric acid pretreatment and hydrothermal synthesis using an [...] Read more.

In this study, carbon-quantum-dot (CQD)-decorated TiO₂ was prepared using an ultrasonic doping method and applied in the photocatalytic degradation of naphthalene under sunlight irradiation. The CQDs were synthesized from a typical macroalgae via diluted sulfuric acid pretreatment and hydrothermal synthesis using an optimal design, i.e., 3 wt% and 200 °C, respectively. The CQD/TiO₂ composite remarkably enhanced the photocatalytic activity. The degradation of naphthalene under a visible light environment indicated that there is a synergistic mechanism between the CQDs and TiO₂, in which the generation of reactive oxygen species is significantly triggered; in addition, the N that originated from the macroalgae accelerated the photocatalytic efficiency. Kinetic analysis showed that the photocatalytic behavior of the CQD/TiO₂ composite followed a pseudo-first-order equation. Consequently, our combined experimental approach not only provides a facile pretreatment process for bio-CQDs synthesis, but also delivers a suitable TiO₂ photocatalyst for the visible environment along with critical insights into the development of harmful macroalgae resources. Full article

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15 pages, 8638 KiB

Open AccessArticle

Effect of Rh Doping on Optical Absorption and Oxygen Evolution Reaction Activity on BaTiO₃ (001) Surfaces

by Talgat M. Inerbaev, Aisulu U. Abuova, Zhadyra Ye. Zakiyeva, Fatima U. Abuova, Yuri A. Mastrikov, Maksim Sokolov, Denis Gryaznov and Eugene A. Kotomin

Molecules 2024, 29(11), 2707; https://doi.org/10.3390/molecules29112707 - 6 Jun 2024

Viewed by 326

Abstract

In the present work, we investigate the potential of modified barium titanate (BaTiO₃), an inexpensive perovskite oxide derived from earth-abundant precursors, for developing efficient water oxidation electrocatalysts using first-principles calculations. Based on our calculations, Rh doping is a way of making [...] Read more.

In the present work, we investigate the potential of modified barium titanate (BaTiO₃), an inexpensive perovskite oxide derived from earth-abundant precursors, for developing efficient water oxidation electrocatalysts using first-principles calculations. Based on our calculations, Rh doping is a way of making BaTiO₃ absorb more light and have less overpotential needed for water to oxidize. It has been shown that a TiO₂-terminated BaTiO₃ (001) surface is more promising from the point of view of its use as a catalyst. Rh doping expands the spectrum of absorbed light to the entire visible range. The aqueous environment significantly affects the ability of Rh-doped BaTiO₃ to absorb solar radiation. After Ti→Rh replacement, the doping ion can take over part of the electron density from neighboring oxygen ions. As a result, during the water oxidation reaction, rhodium ions can be in an intermediate oxidation state between 3+ and 4+. This affects the adsorption energy of reaction intermediates on the catalyst’s surface, reducing the overpotential value. Full article

(This article belongs to the Special Issue Chemistry of Materials for Energy and Environmental Sustainability)

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21 pages, 2024 KiB

Open AccessReview

Advancements in the Synthesis and Functionalization of Zinc Oxide-Based Nanomaterials for Enhanced Oral Cancer Therapy

by Jinjin Pei, Prabhu Manickam Natarajan, Vidhya Rekha Umapathy, Bhuminathan Swamikannu, Nandini Manickam Sivaraman, Lakshmi Krishnasamy and Chella Perumal Palanisamy

Molecules 2024, 29(11), 2706; https://doi.org/10.3390/molecules29112706 - 6 Jun 2024

Viewed by 402

Abstract

The fabrication of zinc oxide-based nanomaterials (including natural and synthetic polymers like sulfated polysaccharide, chitosan, and polymethyl methacrylate) has potential to improve oral cancer treatment strategies. This comprehensive review explores the diverse synthesis methods employed to fabricate zinc oxide nanomaterials tailored for oral [...] Read more.

The fabrication of zinc oxide-based nanomaterials (including natural and synthetic polymers like sulfated polysaccharide, chitosan, and polymethyl methacrylate) has potential to improve oral cancer treatment strategies. This comprehensive review explores the diverse synthesis methods employed to fabricate zinc oxide nanomaterials tailored for oral cancer applications. Several synthesis processes, particularly sol–gel, hydrothermal, and chemical vapor deposition approaches, are thoroughly studied, highlighting their advantages and limitations. The review also examines how synthesis parameters, such as precursor selection, the reaction temperature, and growth conditions, influence both the physicochemical attributes and biological efficacy of the resulting nanomaterials. Furthermore, recent advancements in surface functionalization and modification strategies targeted at improving the targeting specificity and pharmaceutical effectiveness of zinc oxide-based nanomaterials in oral cancer therapy are elucidated. Additionally, the review provides insights into the existing issues and prospective views in the field, emphasizing the need for further research to optimize synthesis methodologies and elucidate the mechanisms underlying the efficacy of zinc oxide-based nanoparticles in oral cancer therapy. Full article

(This article belongs to the Special Issue Nanostructured Materials: Synthesis, Functionalization and Applications in Biomedicine)

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10 pages, 2638 KiB

Open AccessArticle

Reduced Graphene Oxide-Supported SrV₄O₉ Microflowers with Enhanced Electrochemical Performance for Sodium-Ion Batteries

by Guangming Li, Yifan Li, Yi Zhang, Shuguo Lei, Jiwei Hou, Huiling Lu and Baizeng Fang

Molecules 2024, 29(11), 2704; https://doi.org/10.3390/molecules29112704 - 6 Jun 2024

Viewed by 419

Abstract

Sodium-ion batteries (SIBs) have received considerable attention in recent years. Anode material is one of the key factors that determine SIBs’ electrochemical performance. Current commercial hard carbon anode shows poor rate performance, which greatly limits applications of SIBs. In this study, a novel [...] Read more.

Sodium-ion batteries (SIBs) have received considerable attention in recent years. Anode material is one of the key factors that determine SIBs’ electrochemical performance. Current commercial hard carbon anode shows poor rate performance, which greatly limits applications of SIBs. In this study, a novel vanadium-based material, SrV₄O₉, was proposed as an anode for SIBs, and its Na⁺ storage properties were studied for the first time. To enhance the electrical conductivity of SrV₄O₉ material, a microflower structure was designed and reduced graphene oxide (rGO) was introduced as a host to support SrV₄O₉ microflowers. The microflower structure effectively reduced electron diffusion distance, thus enhancing the electrical conductivity of the SrV₄O₉ material. The rGO showed excellent flexibility and electrical conductivity, which effectively improved the cycling life and rate performance of the SrV₄O₉ composite material. As a result, the SrV₄O₉@rGO composite showed excellent electrochemical performance (a stable capacity of 273.4 mAh g⁻¹ after 200 cycles at 0.2 A g⁻¹ and a high capacity of 120.4 mAh g⁻¹ at 10.0 A g⁻¹), indicating that SrV₄O₉@rGO composite can be an ideal anode material for SIBs. Full article

(This article belongs to the Special Issue Battery Chemistry: Recent Advances and Future Opportunities)

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18 pages, 1174 KiB

Open AccessArticle

Electronic and Nuclear Quantum Effects on Proton Transfer Reactions of Guanine–Thymine (G-T) Mispairs Using Combined Quantum Mechanical/Molecular Mechanical and Machine Learning Potentials

by Yujun Tao, Timothy J. Giese and Darrin M. York

Molecules 2024, 29(11), 2703; https://doi.org/10.3390/molecules29112703 - 6 Jun 2024

Viewed by 460

Abstract

Rare tautomeric forms of nucleobases can lead to Watson–Crick-like (WC-like) mispairs in DNA, but the process of proton transfer is fast and difficult to detect experimentally. NMR studies show evidence for the existence of short-time WC-like guanine–thymine (G-T) mispairs; however, the mechanism of [...] Read more.

Rare tautomeric forms of nucleobases can lead to Watson–Crick-like (WC-like) mispairs in DNA, but the process of proton transfer is fast and difficult to detect experimentally. NMR studies show evidence for the existence of short-time WC-like guanine–thymine (G-T) mispairs; however, the mechanism of proton transfer and the degree to which nuclear quantum effects play a role are unclear. We use a B-DNA helix exhibiting a wGT mispair as a model system to study tautomerization reactions. We perform ab initio (PBE0/6-31G*) quantum mechanical/molecular mechanical (QM/MM) simulations to examine the free energy surface for tautomerization. We demonstrate that while the ab initio QM/MM simulations are accurate, considerable sampling is required to achieve high precision in the free energy barriers. To address this problem, we develop a QM/MM machine learning potential correction (QM/MM-

Δ

MLP) that is able to improve the computational efficiency, greatly extend the accessible time scales of the simulations, and enable practical application of path integral molecular dynamics to examine nuclear quantum effects. We find that the inclusion of nuclear quantum effects has only a modest effect on the mechanistic pathway but leads to a considerable lowering of the free energy barrier for the GT*⇌G*T equilibrium. Our results enable a rationalization of observed experimental data and the prediction of populations of rare tautomeric forms of nucleobases and rates of their interconversion in B-DNA. Full article

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

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22 pages, 4130 KiB

Open AccessArticle

Screening of M^pro Protease (SARS-CoV-2) Covalent Inhibitors from an Anthocyanin-Rich Blueberry Extract Using an HRMS-Based Analytical Platform

by Alessandra Altomare, Giovanna Baron, Giulia Cambiaghi, Giulio Ferrario, Beatrice Zoanni, Larissa Della Vedova, Giulio Maria Fumagalli, Sarah D’Alessandro, Silvia Parapini, Serena Vittorio, Giulio Vistoli, Patrizia Riso, Marina Carini, Serena Delbue and Giancarlo Aldini

Molecules 2024, 29(11), 2702; https://doi.org/10.3390/molecules29112702 - 6 Jun 2024

Viewed by 459

Abstract

Background: The viral main protease (M^pro) of SARS-CoV-2 has been recently proposed as a key target to inhibit virus replication in the host. Therefore, molecules that can bind the catalytic site of M^pro could be considered as potential drug candidates [...] Read more.

Background: The viral main protease (M^pro) of SARS-CoV-2 has been recently proposed as a key target to inhibit virus replication in the host. Therefore, molecules that can bind the catalytic site of M^pro could be considered as potential drug candidates in the treatment of SARS-CoV-2 infections. Here we proposed the application of a state-of-the-art analytical platform which combines metabolomics and protein structure analysis to fish-out potential active compounds deriving from a natural matrix, i.e., a blueberry extract. Methods: The experiments focus on finding MS covalent inhibitors of M^pro that contain in their structure a catechol/pyrogallol moiety capable of binding to the nucleophilic amino acids of the enzyme’s catalytic site. Results: Among the potential candidates identified, the delphinidin-3-glucoside showed the most promising results. Its antiviral activity has been confirmed in vitro on Vero E6 cells infected with SARS-CoV-2, showing a dose-dependent inhibitory effect almost comparable to the known M^pro inhibitor baicalin. The interaction of delphinidin-3-glucoside with the M^pro pocket observed was also evaluated by computational studies. Conclusions: The HRMS analytical platform described proved to be effective in identifying compounds that covalently bind M^pro and are active in the inhibition of SARS-CoV-2 replication, such as delphinidin-3-glucoside. Full article

(This article belongs to the Special Issue Antibacterial, Antifungal, and Antiviral Bioactive Compounds from Natural Products, 2nd Edition)

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12 pages, 253 KiB

Open AccessArticle

Accurate Boron Determination in Tourmaline by Inductively Coupled Plasma Mass Spectrometry: An Insight into the Boron–Mannitol Complex-Based Wet Acid Digestion Method

by Xijuan Tan, Yonggang Feng, Ruili Zhou, Denghong Wang, Ting Liang and Yan Wang

Molecules 2024, 29(11), 2701; https://doi.org/10.3390/molecules29112701 - 6 Jun 2024

Viewed by 348

Abstract

Tourmaline, a boron-bearing mineral, has been extensively applied as a geothermometer, provenance indicator, and fluid-composition recorder in geological studies. In this paper, the decomposition capability of an HF-HNO₃–mannitol mixture for a tourmaline sample was investigated in detail for the first time, [...] Read more.

Tourmaline, a boron-bearing mineral, has been extensively applied as a geothermometer, provenance indicator, and fluid-composition recorder in geological studies. In this paper, the decomposition capability of an HF-HNO₃–mannitol mixture for a tourmaline sample was investigated in detail for the first time, and a wet acid digestion method based on the boron–mannitol complex for accurate boron determination in tourmaline by inductively coupled plasma mass spectrometry (ICP-MS) was proposed. With a digestion temperature of 140 °C, tourmaline samples of 25 mg (±0.5 mg) can be completely decomposed by a ternary mixture, which consisted of 0.6 mL of HF, 0.6 mL of HNO₃, and 0.7 mL of 2% mannitol (wt.), via a continuous heating treatment of 36 h. Following gentle evaporation at 100 °C, the sample residues were re-dissolved using 2 mL of 40% HNO₃ solution (wt.) and diluted to about 2.0 × 10⁵-fold by a two-step method using 2% HNO₃ solution (wt.). The boron contents in a batch of parallel tourmaline samples were then determined by ICP-MS, and results showed that the boron concentration levels were in a range of 3.20–3.44% with determination RSDs less than 4.0% (n = 5). It was found that the boron concentrations obtained at the mass of ¹⁰B were comparable with results from the measurements at the mass of ¹¹B. This revealed that the usage of 2% mannitol with a quantity as high as 0.7 mL in this developed approach did not exhibit significant effect on the quantification accuracy of boron at the mass of ¹¹B. It was also found that the processes including fluoride-forming prevention and fluoride decomposition deteriorated the boron-reserving efficiency of mannitol for tourmaline, causing the averaged boron contents to vary from 2.25% to 3.57% (n = 5). Furthermore, the stability of the boron–mannitol complex under 185 °C by applying the laboratory high pressure-closed digestion method was evaluated, which showed that there existed a 60.36% loss of boron compared to that under 140 °C by using this proposed approach. For this ternary mixture, the tourmaline decomposing efficiency was found to be weakened prominently using 100 °C as the digestion temperature, and tourmaline powders can be observed even after 72 h of continuous heating with B contents within 1.09–1.23% (n = 5). To assess the accuracy of this developed method, the boron recovery of anhydrous lithium tetraborate was studied. It was found that the boron recoveries were within 96.59–102.12% (RSD < 1%, n = 5), demonstrating the accuracy and reliability of this proposed method, which exhibits advantages of high B preserving efficiency, and giving concentration information of both B and trace elements simultaneously. By applying such a boron–mannitol complex-based wet acid digestion method, the chemical composition of boron and trace elements in three tourmaline samples from different pegmatites were quantified, which provided valuable information to distinguish regional deposits and the associated evolution stages. Full article

(This article belongs to the Section Analytical Chemistry)

16 pages, 2147 KiB

Open AccessArticle

Graphene Oxide Strengthens Gelatine through Non-Covalent Interactions with Its Amorphous Region

by Hak Jin Sim, Katarina Marinkovic, Ping Xiao and Hui Lu

Molecules 2024, 29(11), 2700; https://doi.org/10.3390/molecules29112700 - 6 Jun 2024

Viewed by 383

Abstract

Graphene oxide (GO) has attracted huge attention in biomedical sciences due to its outstanding properties and potential applications. In this study, we synthesized GO using our recently developed 1-pyrenebutyric acid-assisted method and assessed how the GO as a filler influences the mechanical properties [...] Read more.

Graphene oxide (GO) has attracted huge attention in biomedical sciences due to its outstanding properties and potential applications. In this study, we synthesized GO using our recently developed 1-pyrenebutyric acid-assisted method and assessed how the GO as a filler influences the mechanical properties of GO–gelatine nanocomposite dry films as well as the cytotoxicity of HEK-293 cells grown on the GO–gelatine substrates. We show that the addition of GO (0–2%) improves the mechanical properties of gelatine in a concentration-dependent manner. The presence of 2 wt% GO increased the tensile strength, elasticity, ductility, and toughness of the gelatine films by about 3.1-, 2.5-, 2-, and 8-fold, respectively. Cell viability, apoptosis, and necrosis analyses showed no cytotoxicity from GO. Furthermore, we performed circular dichroism, X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses to decipher the interactions between GO and gelatine. The results show, for the first time, that GO enhances the mechanical properties of gelatine by forming non-covalent intermolecular interactions with gelatine at its amorphous or disordered regions. We believe that our findings will provide new insight and help pave the way for potential and wide applications of GO in tissue engineering and regenerative biomedicine. Full article

(This article belongs to the Special Issue Advances in Nanomaterials for Biomedical Applications)

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14 pages, 2568 KiB

Open AccessArticle

Dispersive Solid Phase Extraction of Melatonin with Graphene/Clay Mixtures and Fluorescence Analysis in Surfactant Aqueous Solutions

by Lucía Gutiérrez-Fernández, Ana M. Díez-Pascual and María Paz San Andrés

Molecules 2024, 29(11), 2699; https://doi.org/10.3390/molecules29112699 - 6 Jun 2024

Viewed by 337

Abstract

In this work, the dispersive solid phase extraction (dSPE) of melatonin using graphene (G) mixtures with sepiolite (SEP) and bentonite (BEN) clays as sorbents combined with fluorescence detection has been investigated. The retention was found to be quantitative for both G/SEP and G/BEN [...] Read more.

In this work, the dispersive solid phase extraction (dSPE) of melatonin using graphene (G) mixtures with sepiolite (SEP) and bentonite (BEN) clays as sorbents combined with fluorescence detection has been investigated. The retention was found to be quantitative for both G/SEP and G/BEN 4/96 and 10/90 w/w mixtures. G/clay 4/96 w/w mixtures were selected to study the desorption process since the retention was weaker, thus leading to easier desorption. MeOH and aqueous solutions of the nonionic surfactant Brij L23 were tested as desorbents. For both clays and an initial sample volume of 25 mL, a percentage of melatonin recovery close to 100% was obtained using 10 or 25 mL of MeOH as desorbent. Further, using a G/SEP mixture, 25 mL as the initial sample volume and 5 mL of MeOH or 60 mM Brij L23 solution as the desorbent, recoveries of 98.3% and 90% were attained, respectively. The whole method was applied to herbal tea samples containing melatonin, and the percentage of agreement with the labeled value was 86.5%. It was also applied to herbal samples without melatonin by spiking them with two concentrations of this compound, leading to recoveries of 100 and 102%. Full article

(This article belongs to the Special Issue Amphiphilic Molecules, Interfaces and Colloids)

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17 pages, 5002 KiB

Open AccessArticle

Mechanochemical Synthesis of MOF-303 and Its CO₂ Adsorption at Ambient Conditions

by Sylwia Głowniak, Barbara Szczęśniak, Jerzy Choma and Mietek Jaroniec

Molecules 2024, 29(11), 2698; https://doi.org/10.3390/molecules29112698 - 6 Jun 2024

Viewed by 450

Abstract

Metal–organic structures have great potential for practical applications in many areas. However, their widespread use is often hindered by time-consuming and expensive synthesis procedures that often involve hazardous solvents and, therefore, generate wastes that need to be remediated and/or recycled. The development of [...] Read more.

Metal–organic structures have great potential for practical applications in many areas. However, their widespread use is often hindered by time-consuming and expensive synthesis procedures that often involve hazardous solvents and, therefore, generate wastes that need to be remediated and/or recycled. The development of cleaner, safer, and more sustainable synthesis methods is extremely important and is needed in the context of green chemistry. In this work, a facile mechanochemical method involving water-assisted ball milling was used for the synthesis of MOF-303. The obtained MOF-303 exhibited a high specific surface area of 1180 m²/g and showed an excellent CO₂ adsorption capacity of 9.5 mmol/g at 0 °C and under 1 bar. Full article

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15 pages, 4692 KiB

Open AccessArticle

Design, Synthesis, and Cytotoxic Assessment of New Haloperidol Analogues as Potential Anticancer Compounds Targeting Sigma Receptors

by Daniele Zampieri, Maurizio Romano, Sara Fortuna, Emanuele Amata, Maria Dichiara, Giuseppe Cosentino, Agostino Marrazzo and Maria Grazia Mamolo

Molecules 2024, 29(11), 2697; https://doi.org/10.3390/molecules29112697 - 6 Jun 2024

Viewed by 334

Abstract

Sigma receptors (SRs), including SR1 and SR2 subtypes, have attracted increasing interest in recent years due to their involvement in a wide range of activities, including the modulation of opioid analgesia, neuroprotection, and potential anticancer activity. In this context, haloperidol (HAL), a commonly [...] Read more.

Sigma receptors (SRs), including SR1 and SR2 subtypes, have attracted increasing interest in recent years due to their involvement in a wide range of activities, including the modulation of opioid analgesia, neuroprotection, and potential anticancer activity. In this context, haloperidol (HAL), a commonly used antipsychotic drug, also possesses SR activity and cytotoxic effects. Herein, we describe the identification of novel SR ligands, obtained by a chemical hybridization approach. There wereendowed with pan-affinity for both SR subtypes and evaluated their potential anticancer activity against SH-SY5Y and HUH-7 cancer cell lines. Through a chemical hybridization approach, we identified novel compounds (4d, 4e, 4g, and 4j) with dual affinity for SR1 and SR2 receptors. These compounds were subjected to cytotoxicity testing using a resazurin assay. The results revealed potent cytotoxic effects against both cancer cell lines, with IC₅₀ values comparable to HAL. Interestingly, the cytotoxic potency of the novel compounds resembled that of the SR1 antagonist HAL rather than the SR2 agonist siramesine (SRM), indicating the potential role of SR1 antagonism in their mechanism of action. The further exploration of their structure-activity relationships and their evaluation in additional cancer cell lines will elucidate their therapeutic potential and may pave the way for the development of novel anticancer agents that target SRs. Full article

(This article belongs to the Special Issue Small Molecules in Targeted Cancer Therapy)

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12 pages, 810 KiB

Open AccessArticle

Synthesis and Characterization of Cross-Linked Aggregates of Peroxidase from Megathyrsus maximus (Guinea Grass) and Their Application for Indigo Carmine Decolorization

by Angie V. Perez, Jorge A. Gaitan-Oyola, Diana P. Vargas-Delgadillo, John J. Castillo, Oveimar Barbosa and Roberto Fernandez-Lafuente

Molecules 2024, 29(11), 2696; https://doi.org/10.3390/molecules29112696 - 6 Jun 2024

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Abstract

We present the synthesis of a cross-linking enzyme aggregate (CLEAS) of a peroxidase from Megathyrsus maximus (Guinea Grass) (GGP). The biocatalyst was produced using 50%v/v ethanol and 0.88%w/v glutaraldehyde for 1 h under stirring. The immobilization yield [...] Read more.

We present the synthesis of a cross-linking enzyme aggregate (CLEAS) of a peroxidase from Megathyrsus maximus (Guinea Grass) (GGP). The biocatalyst was produced using 50%v/v ethanol and 0.88%w/v glutaraldehyde for 1 h under stirring. The immobilization yield was 93.74% and the specific activity was 36.75 U mg⁻¹. The biocatalyst surpassed by 61% the free enzyme activity at the optimal pH value (pH 6 for both preparations), becoming this increase in activity almost 10-fold at pH 9. GGP-CLEAS exhibited a higher thermal stability (2–4 folds) and was more stable towards hydrogen peroxide than the free enzyme (2–3 folds). GGP-CLEAS removes over 80% of 0.05 mM indigo carmine at pH 5, in the presence of 0.55 mM H₂O₂ after 60 min of reaction, a much higher value than when using the free enzyme. The operational stability showed a decrease of enzyme activity (over 60% in 4 cycles), very likely related to suicide inhibition. Full article

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14 pages, 5404 KiB

Open AccessArticle

Pickering Emulsion of Oleoresin from Dipterocarpus alatus Roxb. ex G. Don and Its Antiproliferation in Colon (HCT116) and Liver (HepG2) Cancer Cells

by Piman Pocasap, Kawintra Tamprasit, Thanyathanya Rungsri, Karnchanok Kaimuangpak, Tarapong Srisongkram, Somporn Katekaew, Khanita Kamwilaisak, Ploenthip Puthongking and Natthida Weerapreeyakul

Molecules 2024, 29(11), 2695; https://doi.org/10.3390/molecules29112695 - 6 Jun 2024

Viewed by 450

Abstract

Oleoresin of Dipterocarpus alatus Roxb. ex G. Don (DA) has been traditionally used for local medicinal applications. Several in vitro studies have indicated its pharmacological potential. However, the low water solubility hinders its use and development for pharmaceutical purposes. The study aimed to [...] Read more.

Oleoresin of Dipterocarpus alatus Roxb. ex G. Don (DA) has been traditionally used for local medicinal applications. Several in vitro studies have indicated its pharmacological potential. However, the low water solubility hinders its use and development for pharmaceutical purposes. The study aimed to (1) formulate oil-in-water (o/w) Pickering emulsions of DA oleoresin and (2) demonstrate its activities in cancer cells. The Pickering emulsions were formulated using biocompatible carboxylated cellulose nanocrystal (cCNC) as an emulsifier. The optimized emulsion comprised 3% (F1) and 4% (v/v) (F2) of oleoresin in 1% cCNC and 0.1 M NaCl, which possessed homogeneity and physical stability compared with other formulations with uniform droplet size and low viscosity. The constituent analysis indicated the presence of the biomarker dipterocarpol in both F1 and F2. The pharmacological effects of the two emulsions were demonstrated in vitro against two cancer cell lines, HepG2 and HCT116. Both F1 and F2 suppressed cancer cell viability. The treated cells underwent apoptosis, as demonstrated by distinct nuclear morphological changes in DAPI-stained cells and Annexin V/PI-stained cells detected by flow cytometry. Our study highlights the prospect of Pickering emulsions for oleoresin, emphasizing enhanced stability and potential pharmacological advantages. Full article

(This article belongs to the Special Issue Natural Products in Anticancer Activity)

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20 pages, 2849 KiB

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UPLC-ESI-MS/MS Profiling of Secondary Metabolites from Methanol Extracts of In Vivo and In Vitro Tissues of Daucus capillifolius Gilli (A Comparative Study)

by Rehab H. Abdallah, Wafaa H. B. Hassan, Shaza M. Al-Massarani, Wael M. Abdel-Mageed, Samih I. Eldahmy, Omer A. Basudan, Mehtab Parveen, Entesar El Senosy and Sahar Abdelaziz

Molecules 2024, 29(11), 2694; https://doi.org/10.3390/molecules29112694 - 6 Jun 2024

Viewed by 369

Abstract

Daucus capillifolius Gilli is a rare annual wild herb grown in Libya. It belongs to the Apiaceae family, which is one of the largest flowering plant families. Plants of this family are outstanding sources of various secondary metabolites with various biological activities. A [...] Read more.

Daucus capillifolius Gilli is a rare annual wild herb grown in Libya. It belongs to the Apiaceae family, which is one of the largest flowering plant families. Plants of this family are outstanding sources of various secondary metabolites with various biological activities. A UPLC-ESI-MS/MS analysis of different extracts of in vivo and in vitro tissues of Daucus capillifolius together with the fruit extract of the cultivated plant in both ionization modes was carried out for the first time in the current study. Our results reveal the tentative identification of eighty-seven compounds in the tested extracts, including thirty-two phenolic acids and their derivatives; thirty-seven flavonoid glycosides and aglycones of apigenin, luteolin, diosmetin, myricetin and quercetin, containing glucose, rhamnose, pentose and/or glucuronic acid molecules; seven anthocyanins; six tannins; three acetylenic compounds; and three nitrogenous compounds. The tentative identification of the above compounds was based on the comparison of their retention times and ESI-MS/MS fragmentation patterns with those previously reported in the literature. For this Apiaceae plant, our results confirm the presence of a wide array of secondary metabolites with reported biological activities. This study is among the first ones to shed light on the phytoconstituents of this rare plant. Full article

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16 pages, 4396 KiB

Open AccessArticle

Preparation, Characterization, and Antioxidant Properties of Self-Assembled Nanomicelles of Curcumin-Loaded Amphiphilic Modified Chitosan

by Qizhou Chen, Yuwei Jiang, Linlan Yuan, Lifen Liu, Xufeng Zhu, Rimeng Chen, Zhuo Wang, Kefeng Wu, Hui Luo and Qianqian Ouyang

Molecules 2024, 29(11), 2693; https://doi.org/10.3390/molecules29112693 - 6 Jun 2024

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Abstract

Curcumin (Cur) is a phytochemical with various beneficial properties, including antioxidant, anti-inflammatory, and anticancer activities. However, its hydrophobicity, poor bioavailability, and stability limit its application in many biological approaches. In this study, a novel amphiphilic chitosan wall material was synthesized. The process was [...] Read more.

Curcumin (Cur) is a phytochemical with various beneficial properties, including antioxidant, anti-inflammatory, and anticancer activities. However, its hydrophobicity, poor bioavailability, and stability limit its application in many biological approaches. In this study, a novel amphiphilic chitosan wall material was synthesized. The process was carried out via grafting chitosan with succinic anhydride (SA) as a hydrophilic group and deoxycholic acid (DA) as a hydrophobic group; ¹H-NMR, FTIR, and XRD were employed to characterize the amphiphilic chitosan (CS—SA—DA). Using a low-cost, inorganic solvent-based procedure, CS—SA—DA was self-assembled to load Cur nanomicelles. This amphiphilic polymer formed self-assembled micelles with a core–shell structure and a critical micelle concentration (CMC) of 0.093 mg·mL⁻¹. Cur-loaded nanomicelles were prepared by self-assembly and characterized by the Nano Particle Size Potential Analyzer and transmission electron microscopy (TEM). The mean particle size of the spherical Cur-loaded micelles was 770 nm. The drug entrapment efficiency and loading capacities were up to 80.80 ± 0.99% and 19.02 ± 0.46%, respectively. The in vitro release profiles of curcumin from micelles showed a constant release of the active drug molecule. Cytotoxicity studies and toxicity tests for zebrafish exhibited the comparable efficacy and safety of this delivery system. Moreover, the results showed that the entrapment of curcumin in micelles improves its stability, antioxidant, and anti-inflammatory activity. Full article

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16 pages, 3737 KiB

Open AccessArticle

Screening the Optimal Probe by Expounding the ESIPT Mechanism and Photophysical Properties in Bis-HBX with Multimodal Substitutions

by Min Yang, Hongyan Mu, Jiaan Gao, Qi Zhen, Xiaonan Wang, Xiaotong Guan, Hui Li and Bo Li

Molecules 2024, 29(11), 2692; https://doi.org/10.3390/molecules29112692 - 6 Jun 2024

Viewed by 306

Abstract

DFT and TD-DFT were used in this article to investigate the effects of different substitutions at multiple sites on the photophysical mechanism of bis-HBX in the gas phase. Four different substitution modes were selected, denoted as A₁ (X=Me, Y=S), A₂ (X=OMe, [...] Read more.

DFT and TD-DFT were used in this article to investigate the effects of different substitutions at multiple sites on the photophysical mechanism of bis-HBX in the gas phase. Four different substitution modes were selected, denoted as A₁ (X=Me, Y=S), A₂ (X=OMe, Y=S), B₁ (X=Me, Y=NH), and C₁ (X=Me, Y=O). The geometric parameters proved that the IHBs enhanced after photoexcitation, which was conducive to promote the ESIPT process. Combining the analysis of the PECs, it was revealed that the bis-HBX molecule underwent the ESIPT process, and the ease of the ESIPT process was in the order of A₁ > A₂> B₁ > C₁. In particular, the TICT process in A₁ and B₁ promoted the occurrence of the ESIPT process. In addition, the IC process was identified, particularly in C₁. Meanwhile, the calculation of fluorescence lifetime and fluorescence rate further confirmed that A₁ was the most effective fluorescent probe molecule. This theoretical research provides an innovative theoretical reference for regulating ESIPT reactions and optimizing fluorescent probe molecules. Full article

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

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17 pages, 4684 KiB

Open AccessArticle

L-Theanine Prolongs the Lifespan by Activating Multiple Molecular Pathways in Ultraviolet C-Exposed Caenorhabditis elegans

by Liangwen Chen, Guijie Chen, Tingting Gai, Xiuhong Zhou, Jinchi Zhu, Ruiyi Wang, Xuemei Wang, Yujie Guo, Yun Wang and Zhongwen Xie

Molecules 2024, 29(11), 2691; https://doi.org/10.3390/molecules29112691 - 6 Jun 2024

Viewed by 568

Abstract

L-theanine, a unique non-protein amino acid, is an important bioactive component of green tea. Previous studies have shown that L-theanine has many potent health benefits, such as anti-anxiety effects, regulation of the immune response, relaxing neural tension, and reducing oxidative damage. However, little [...] Read more.

L-theanine, a unique non-protein amino acid, is an important bioactive component of green tea. Previous studies have shown that L-theanine has many potent health benefits, such as anti-anxiety effects, regulation of the immune response, relaxing neural tension, and reducing oxidative damage. However, little is known concerning whether L-theanine can improve the clearance of mitochondrial DNA (mtDNA) damage in organisms. Here, we reported that L-theanine treatment increased ATP production and improved mitochondrial morphology to extend the lifespan of UVC-exposed nematodes. Mechanistic investigations showed that L-theanine treatment enhanced the removal of mtDNA damage and extended lifespan by activating autophagy, mitophagy, mitochondrial dynamics, and mitochondrial unfolded protein response (UPR^mt) in UVC-exposed nematodes. In addition, L-theanine treatment also upregulated the expression of genes related to mitochondrial energy metabolism in UVC-exposed nematodes. Our study provides a theoretical basis for the possibility that tea drinking may prevent mitochondrial-related diseases. Full article

(This article belongs to the Special Issue Advances in Natural Products and Their Biological Activities)

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16 pages, 11694 KiB

Open AccessArticle

Solvothermal Synthesis of Rare Earth Bisphthalocyanines

by Lina M. Bolivar-Pineda, Carlos U. Mendoza-Domínguez, Petra Rudolf, Elena V. Basiuk and Vladimir A. Basiuk

Molecules 2024, 29(11), 2690; https://doi.org/10.3390/molecules29112690 - 6 Jun 2024

Viewed by 346

Abstract

Rare earth bisphthalocyanines (MPc₂) are of particular interest because of their behavior as single-molecular magnets, which makes them suitable for applications in molecular spintronics, high-density data storage and quantum computation. Nevertheless, MPc₂ are not commercially available, and the synthesis routes [...] Read more.

Rare earth bisphthalocyanines (MPc₂) are of particular interest because of their behavior as single-molecular magnets, which makes them suitable for applications in molecular spintronics, high-density data storage and quantum computation. Nevertheless, MPc₂ are not commercially available, and the synthesis routes are mainly focused on obtaining substituted phthalocyanines. Two preparation routes depend on the precursor: synthesis from phthalonitrile (PN) and the metalation of free or dilithium phthalocyanine (H₂Pc and Li₂Pc). In both options, byproducts such as free-base phthalocyanine and in the first route additional PN oligomers are generated, which influence the MPc₂ yield. There are three preparation methods for these routes: heating, microwave radiation and reflux. In this research, solvothermal synthesis was applied as a new approach to prepare yttrium, lanthanum, gadolinium and terbium unsubstituted bisphthalocyanines using Li₂Pc and the rare earth(III) acetylacetonates. Purification by sublimation gave high product yields compared to those reported, namely 68% for YPc₂, 43% for LaPc₂, 63% for GdPc₂ and 62% for TbPc₂, without any detectable presence of H₂Pc. Characterization by infrared, Raman, ultraviolet–visible and X-ray photoelectron spectroscopy as well as elemental analysis revealed the main featuresof the four bisphthalocyanines, indicating the success of the synthesis of the complexes. Full article

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15 pages, 2068 KiB

Open AccessArticle

Organosiloxane-Modified Auricularia Polysaccharide (Si-AP): Improved High-Temperature Resistance and Lubrication Performance in WBDFs

by Fan Zhang, Yu Wang, Bo Wang, Yuan Geng, Xiaofeng Chang, Wenzhe Zhang, Yutong Li and Wangyuan Zhang

Molecules 2024, 29(11), 2689; https://doi.org/10.3390/molecules29112689 - 6 Jun 2024

Viewed by 333

Abstract

This study introduces a novel organosilicon-modified polysaccharide (Si-AP) synthesized via grafting and comprehensively evaluates its performance in water-based drilling fluids (WBDFs). The molecular structure of Si-AP was characterized using Fourier-transform infrared spectroscopy (FTIR) and ¹H-NMR experiments. Thermalgravimetric analysis (TGA) confirmed the good [...] Read more.

This study introduces a novel organosilicon-modified polysaccharide (Si-AP) synthesized via grafting and comprehensively evaluates its performance in water-based drilling fluids (WBDFs). The molecular structure of Si-AP was characterized using Fourier-transform infrared spectroscopy (FTIR) and ¹H-NMR experiments. Thermalgravimetric analysis (TGA) confirmed the good thermal stability of Si-AP up to 235 °C. Si-AP significantly improves the rheological properties and fluid loss performance of WBDFs. With increasing Si-AP concentration, system viscosity increases, API filtration rate decreases, clay expansion is inhibited, and drilling cuttings hydration dispersion is suppressed, especially under high-temperature conditions. Additionally, mechanistic analysis indicates that the introduction of siloxane groups can effectively inhibit the thermal degradation of AP chains and enhance their high-temperature resistance. Si-AP can form a lubricating film by adsorbing on the surface of clay particles, improving mud cake quality, reducing the friction coefficient, and significantly enhancing the lubricating performance of WBDFs. Overall, Si-AP exhibits a higher temperature-resistance limit compared to AP and more effectively optimizes the lubrication, inhibition, and control of the filtration rate of WBDFs under high-temperature conditions. While meeting the requirements of drilling fluid systems under high temperatures, Si-AP also addresses environmental concerns and holds promise as an efficient solution for the exploitation of deep-seated oil and gas resources. Full article

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12 pages, 3444 KiB

Open AccessArticle

Bimetallic Perthiocarbonate Complexes of Cobalt: Synthesis, Structure and Bonding

by Alaka Nanda Pradhan, Shivankan Mishra, Urminder Kaur, Bikram Keshari Rout, Jean-François Halet and Sundargopal Ghosh

Molecules 2024, 29(11), 2688; https://doi.org/10.3390/molecules29112688 - 6 Jun 2024

Viewed by 389

Abstract

The syntheses and structural elucidation of bimetallic thiolate complexes of early and late transition metals are described. Thermolysis of the bimetallic hydridoborate species [{Cp*CoPh}{µ-TePh}{µ-TeBH₃-ĸ²Te,H}{Cp*Co}] (Cp* = ɳ⁵-C₅Me₅) ( [...] Read more.

The syntheses and structural elucidation of bimetallic thiolate complexes of early and late transition metals are described. Thermolysis of the bimetallic hydridoborate species [{Cp*CoPh}{µ-TePh}{µ-TeBH₃-ĸ²Te,H}{Cp*Co}] (Cp* = ɳ⁵-C₅Me₅) (1) in the presence of CS₂ afforded the bimetallic perthiocarbonate complex [(Cp*Co)₂(μ-CS₄-κ¹S:κ²S′)(μ-S₂-κ²S″:κ¹S‴)] (2) and the dithiolene complex [(Cp*Co)(μ-C₃S₅-κ¹S,S′] (3). Complex 2 contains a four-membered metallaheterocycle (Co₂S₂) comprising a perthiocarbonate [CS₄]²⁻ unit and a disulfide [S₂]²⁻ unit, attached opposite to each other. Complex 2 was characterized by employing different multinuclear NMR, infrared spectroscopy, mass spectrometry, and single-crystal X-ray diffraction studies. Preliminary studies show that [Cp*VCl₂]₃ (4) with an intermediate generated from CS₂ and [LiBH₄·THF] yielded thiolate species, albeit different from the cobalt system. Furthermore, a computational analysis was performed to provide insight into the bonding of this bimetallic perthiocarbonate complex. Full article

(This article belongs to the Special Issue Exclusive Feature Papers in Inorganic Chemistry 2.0)

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12 pages, 880 KiB

Open AccessArticle

An Attempt to Replace Pure Citric Acid with Natural Lemon Juice during Potato Starch Esterification

by Ewa Tomaszewska-Ciosk, Ewa Zdybel, Małgorzata Kapelko-Żeberska, Bartosz Raszewski, Krzysztof Buksa, Agnieszka Maj, Tomasz Zięba and Artur Gryszkin

Molecules 2024, 29(11), 2687; https://doi.org/10.3390/molecules29112687 - 6 Jun 2024

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Abstract

The application of chemical operations in food processing, in which pure chemical compounds are used to modify food ingredients, often raises social concerns. One of the most frequently modified dietary substances is starch, e.g., E1401–E1404, E1412–E1414, E1420, E1422, E1440, E1442, and E1450–E1452. An [...] Read more.

The application of chemical operations in food processing, in which pure chemical compounds are used to modify food ingredients, often raises social concerns. One of the most frequently modified dietary substances is starch, e.g., E1401–E1404, E1412–E1414, E1420, E1422, E1440, E1442, and E1450–E1452. An alternative solution to chemical treatments seems to be the use of raw materials naturally containing substrates applied for starch modification. Heating starch with a lemon juice concentrate can be considered a novel and effective method for producing starch citrate, which is part of the so-called “green chemistry”. The modified preparations obtained as a result of potato starch esterification with natural lemon juice had a comparable degree of esterification to that of the esters produced with pure citric acid. In addition, the use of the juice doubled their resistance to amylolytic enzymes compared to the preparations made with pure acid. Replacing citric acid with lemon juice can facilitate the esterification process, and the analyzed properties of both types of modified preparations indicate that starch esters produced with pure citric acid can be successfully replaced by those produced using natural lemon juice, which may increase the social acceptance of these modified preparations. Full article

(This article belongs to the Special Issue Food Polysaccharides: Structure, Properties and Application II)

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15 pages, 5618 KiB

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Thermal Stability of Dispersions of Amino-Functionalized Silica in Glycol and in 50–50 Aqueous Glycol

by Marta Kalbarczyk, Sebastian Skupiński and Marek Kosmulski

Molecules 2024, 29(11), 2686; https://doi.org/10.3390/molecules29112686 - 6 Jun 2024

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Abstract

Dispersions of amino-functionalized silica in ethylene glycol (EG) and in aqueous glycol show excellent stability at room temperature. Stability at elevated temperatures would be much desired with respect to their potential application as heat-transfer fluids. Amino-functionalized silica was dispersed in EG and in [...] Read more.

Dispersions of amino-functionalized silica in ethylene glycol (EG) and in aqueous glycol show excellent stability at room temperature. Stability at elevated temperatures would be much desired with respect to their potential application as heat-transfer fluids. Amino-functionalized silica was dispersed in EG and in 50–50 aqueous EG by mass. HCl and acetic acid were added to enhance the positive ζ potential. The dispersions were stored at 40, 60, 80, and 100 °C for up to 28 days, and ζ potential and apparent particle radius were studied as a function of elapsed time. The particles showed a positive ζ potential in excess of 40 mV (Smoluchowski), which remained unchanged for 28 days. Such a high absolute value of ζ potential is sufficient to stabilize the dispersion against flocculation and sedimentation. The apparent particle radius in acidified dispersions was about 70 nm, and it was stable for 28 days. The particles were larger in pH-neutral dispersions. The apparent particle radius was about 80 nm in fresh dispersions and it increased on long storage at 80 and 100 °C. Full article

(This article belongs to the Section Physical Chemistry)

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11 pages, 5576 KiB

Open AccessArticle

Chalcogen-Bond-Assisted Formation of the N→C Dative Bonds in the Complexes between Chalcogenadiazoles/Chalcogenatriazoles and Fullerene C₆₀

by Yu Zhang and Weizhou Wang

Molecules 2024, 29(11), 2685; https://doi.org/10.3390/molecules29112685 - 6 Jun 2024

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Abstract

The existence of the N→C dative bonds in the complexes between N-containing molecules and fullerenes have been verified both theoretically and experimentally. However, finding stable N→C dative bonds is still a highly challenging task. In this work, we investigated computationally the N→C dative [...] Read more.

The existence of the N→C dative bonds in the complexes between N-containing molecules and fullerenes have been verified both theoretically and experimentally. However, finding stable N→C dative bonds is still a highly challenging task. In this work, we investigated computationally the N→C dative bonds in the complexes formed by fullerene C₆₀ with 1,2,5-chalcogenadiazoles, 2,1,3-benzochalcogenadiazoles, and 1,2,4,5-chalcogenatriazoles, respectively. It was found that the N→C dative bonds are formed along with the formation of the N–Ch···C (Ch = S, Se, Te) chalcogen bonds. In the gas phase, from S-containing complexes through Se-containing complexes to Te-containing complexes, the intrinsic interaction energies become more and more negative, which indicates that the N–Ch···C chalcogen bonds can facilitate the formation of the N→C dative bonds. The intrinsic interaction energies are compensated by the large deformation energy of fullerene C₆₀. The total interaction energies of Te-containing complexes are negative, while both total interaction energies of the S-containing complexes and Se-containing complexes are positive. This means that the N→C dative bonds in the Te-containing complexes are more easily observed in experiments in comparison with those in the S-containing complexes and Se-containing complexes. This study provides a new theoretical perspective on the experimental observation of the N→C dative bonds in complexes involving fullerenes. Further, the formation of stable N→C dative bonds in the complexes involving fullerenes can significantly change the properties of fullerenes, which will greatly simulate and expand the application range of fullerenes. Full article

(This article belongs to the Special Issue Gulliver in the Country of Lilliput: An Interplay of Noncovalent Interactions (Volume II))

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10 pages, 1738 KiB

Open AccessArticle

Synthesis of Unsymmetrically Condensed Benzo- and Thienotriazologermoles

by Cong-Huan Wang, Yohei Adachi and Joji Ohshita

Molecules 2024, 29(11), 2684; https://doi.org/10.3390/molecules29112684 - 5 Jun 2024

Viewed by 414

Abstract

Germoles and siloles unsymmetrically condensed with heteroaromatic units are attracting much interest. In this study, compounds containing a triazologermole core unit condensed with a benzene or thiophene ring were prepared. Thienotriazologermole was subjected to bromination to obtain the bromide, which underwent transformation via [...] Read more.

Germoles and siloles unsymmetrically condensed with heteroaromatic units are attracting much interest. In this study, compounds containing a triazologermole core unit condensed with a benzene or thiophene ring were prepared. Thienotriazologermole was subjected to bromination to obtain the bromide, which underwent transformation via the palladium-catalyzed Stille coupling reaction to form triphenylamine-substituted thienotriazolegermole, with an effective extension of conjugation. The electronic states and properties of these triazologermole derivatives are discussed on the basis of optical and electrochemical measurements and density functional theory calculations. Triphenylamine-substituted thienotriazolegermole showed clear solvatochromic properties in photoluminescence measurements, suggesting that intramolecular charge transfer occurs at the photo-excited state. This clearly indicates that the triazologermole unit is useful as an acceptor of donor–acceptor compounds. The potential application of triphenylamine-substituted thienotriazolegermole as a sensing material was also explored. Full article

(This article belongs to the Section Organometallic Chemistry)

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23 pages, 10067 KiB

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The Isolation, Structural Characterization and Anti-Inflammatory Potentials of Neutral Polysaccharides from the Roots of Isatis indigotica Fort.

by Yu Shen, Shihao Wu, Mingming Song, Huiming Zhang, Hong Zhao, Lili Wu, Hongbo Zhao, Hongbin Qiu and Yu Zhang

Molecules 2024, 29(11), 2683; https://doi.org/10.3390/molecules29112683 - 5 Jun 2024

Viewed by 382

Abstract

Polysaccharides have been assessed as a potential natural active component in Chinese herbal medicine with anti-inflammatory properties. However, the complex and indefinite structures of polysaccharides limit their applications. This study explains the structures and anti-inflammatory potentials of three neutral polysaccharides, RIP-A1 (M_w [...] Read more.

Polysaccharides have been assessed as a potential natural active component in Chinese herbal medicine with anti-inflammatory properties. However, the complex and indefinite structures of polysaccharides limit their applications. This study explains the structures and anti-inflammatory potentials of three neutral polysaccharides, RIP-A1 (M_w 1.8 × 10⁴ Da), RIP-B1 (M_w 7.4 × 10⁴ Da) and RIP-B2 (M_w 9.3 × 10⁴ Da), which were isolated from the roots of Isatis indigotica Fort. with sequenced ultrafiltration membrane columns, DEAE-52 and Sephadex G-100. The planar structures and microstructures of RIP-A1, RIP-B1 and RIP-B2 were further determined by HPGPC, GC–MS, methylation analysis, FT-IR, SEM and AFM, in which the structure of RIP-A1 was elucidated in detail using 1D/2D NMR. The Raw 264.7 cells were used for the anti-inflammatory activity in vitro. The results showed that RIP-A1, RIP-B1 and RIP-B2 are all neutral polysaccharides, with RIP-A1 having the smallest M_w and the simplest monosaccharide composition of the three. RIP-A1 is mainly composed of Ara and Gal, except for a small quantity of Rha. Its main structure is covered with glycosidic linkages of T-α-Araf, 1,2-α-Rhap, 1,5-α-Araf, T-β-Galp, 1,2,4-α-Rhap, 1,3,5-α-Araf and 1,6-β-Galp with 0.33:0.12:1.02:0.09:0.45:11.41:10.23. RIP-A1 significantly inhibited pro-inflammatory cytokines (NO, TNF-α, IL-6 and IL-1β) and increased anti-inflammatory cytokines (IL-4) in LPS-stimulated RAW 264.7 cells. Moreover, RIP-A1 could significantly inhibit the mRNA expression of TNF-α, IL-6 and L-1β. It could also activate IKK, p65 and IκBα (the components of the NF-κB signaling pathway). In conclusion, the above results show the structural characterization and anti-inflammatory potentials of RIP-A1 as an effective natural anti-inflammatory drug. Full article

(This article belongs to the Special Issue Research and Application of Plant Sourced Polysaccharides—2nd Edition)

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