Molecules

27 pages, 5734 KiB

Open AccessArticle

Developing Photoactive Coumarin-Caged N-Hydroxysulfonamides for Generation of Nitroxyl (HNO)

by Mohammad S. Rahman, Vinay Bharadwaj, Anau K. H. S. Lautaha, Paul Sampson, Nicola E. Brasch and Alexander J. Seed

Molecules 2024, 29(16), 3918; https://doi.org/10.3390/molecules29163918 (registering DOI) - 19 Aug 2024

Abstract

Photoactive N-hydroxysulfonamides photocaged with the (6-bromo-7-hydroxycoumarin-4-yl)methyl chromophore have been successfully synthesized, and the mechanisms of photodecomposition investigated for two of the compounds. Upon irradiation up to 97% of a diagnostic marker for (H)NO release, sulfinate was observed for the trifluoromethanesulfonamide system. In [...] Read more.

Photoactive N-hydroxysulfonamides photocaged with the (6-bromo-7-hydroxycoumarin-4-yl)methyl chromophore have been successfully synthesized, and the mechanisms of photodecomposition investigated for two of the compounds. Upon irradiation up to 97% of a diagnostic marker for (H)NO release, sulfinate was observed for the trifluoromethanesulfonamide system. In the absence of a species that reacts rapidly with (H)NO, (H)NO instead reacts with the carbocation intermediate to ultimately generate (E)-BHC-oxime and (Z)-BHC-oxime. Alternatively, the carbocation intermediate reacts with solvent water to give a diol. Deprotonation of the N(H) proton is required for HNO generation via concerted C-O/N-S bond cleavage, whereas the protonation state of the O(H) does not affect the observed photoproducts. If the N(H) is protonated, C-O bond cleavage to generate the parent N-hydroxysulfonamide will occur, and/or O-N bond cleavage to generate a sulfonamide. The undesired competing O-N bond cleavage pathway increases when the volume percentage of water in acetonitrile/water solvent mixtures is increased. Full article

(This article belongs to the Special Issue Synthesis and Application of Photoactive Compounds)

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16 pages, 1124 KiB

Open AccessArticle

Anti-Biofilm Effect of Hybrid Nanocomposite Functionalized with Erythrosine B on Staphylococcus aureus Due to Photodynamic Inactivation

by Larysa Bugyna, Katarína Bilská, Peter Boháč, Marek Pribus, Juraj Bujdák and Helena Bujdáková

Molecules 2024, 29(16), 3917; https://doi.org/10.3390/molecules29163917 - 19 Aug 2024

Abstract

Resistant biofilms formed by Staphylococcus aureus on medical devices pose a constant medical threat. A promising alternative to tackle this problem is photodynamic inactivation (PDI). This study focuses on a polyurethane (PU) material with an antimicrobial surface consisting of a composite based on [...] Read more.

Resistant biofilms formed by Staphylococcus aureus on medical devices pose a constant medical threat. A promising alternative to tackle this problem is photodynamic inactivation (PDI). This study focuses on a polyurethane (PU) material with an antimicrobial surface consisting of a composite based on silicate, polycation, and erythrosine B (EryB). The composite was characterized using X-ray diffraction and spectroscopy methods. Anti-biofilm effectiveness was determined after PDI by calculation of CFU mL⁻¹. The liquid PU precursors penetrated a thin silicate film resulting in effective binding of the PU/silicate composite and the PU bulk phases. The incorporation of EryB into the composite matrix did not significantly alter the spectral properties or photoactivity of the dye. A green LED lamp and laser were used for PDI, while irradiation was performed for different periods. Preliminary experiments with EryB solutions on planktonic cells and biofilms optimized the conditions for PDI on the nanocomposite materials. Significant eradication of S. aureus biofilm on the composite surface was achieved by irradiation with an LED lamp and laser for 1.5 h and 10 min, respectively, resulting in a 10,000-fold reduction in biofilm growth. These results demonstrate potential for the development of antimicrobial polymer surfaces for modification of medical materials and devices. Full article

(This article belongs to the Special Issue Nanocomposites Synthesis, Functionalization and Applications for Medical Purposes)

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17 pages, 7484 KiB

Open AccessReview

Recent Advances in Carborane-Based Crystalline Porous Materials

by Yuxuan Meng, Xi Lin, Jinyi Huang and Liangliang Zhang

Molecules 2024, 29(16), 3916; https://doi.org/10.3390/molecules29163916 (registering DOI) - 19 Aug 2024

Abstract

The field of carborane research has witnessed continuous development, leading to the construction and development of a diverse range of crystalline porous materials for various applications. Moreover, innovative synthetic approaches are expanding in this field. Since the first report of carborane-based crystalline porous [...] Read more.

The field of carborane research has witnessed continuous development, leading to the construction and development of a diverse range of crystalline porous materials for various applications. Moreover, innovative synthetic approaches are expanding in this field. Since the first report of carborane-based crystalline porous materials (CCPMs) in 2007, the synthesis of carborane ligands, particularly through innovative methods, has consistently posed a significant challenge in discovering new structures of CCPMs. This paper provides a comprehensive summary of recent advances in various synthetic approaches for CCPMs, along with their applications in different domains. The primary challenges and future opportunities are expected to stimulate further multidisciplinary development in the field of CCPMs. Full article

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9 pages, 2245 KiB

Open AccessArticle

Prediction of Two-Dimensional Janus Transition-Metal Chalcogenides: Robust Ferromagnetic Semiconductor with High Curie Temperature

by Zijin Wang, Ali Hamza Qureshi, Yuanyuan Duan, Yujie Liu, Yanbiao Wang, Jun Zhu, Jinlian Lu, Tianxia Guo, Yongjun Liu and Xiuyun Zhang

Molecules 2024, 29(16), 3915; https://doi.org/10.3390/molecules29163915 - 19 Aug 2024

Abstract

Two-dimensional (2D) ferromagnetic semiconductors (FM SCs) provide an ideal platform for the development of quantum information technology in nanoscale devices. However, many developed 2D FM materials present a very low Curie temperature (T_C), greatly limiting their application in spintronic devices. In [...] Read more.

Two-dimensional (2D) ferromagnetic semiconductors (FM SCs) provide an ideal platform for the development of quantum information technology in nanoscale devices. However, many developed 2D FM materials present a very low Curie temperature (T_C), greatly limiting their application in spintronic devices. In this work, we predict two stable 2D transition metal chalcogenides, V₃Se₃X₂ (X = S, Te) monolayers, by using first-principles calculations. Our results show that the V₃Se₃Te₂ monolayer is a robust bipolar magnetic SC with a moderate bandgap of 0.53 eV, while V₃Se₃S₂ is a direct band-gap FM SC with a bandgap of 0.59 eV. Interestingly, the ferromagnetisms of both monolayers are robust due to the V–S/Se/Te–V superexchange interaction, and T_Cs are about 406 K and 301 K, respectively. Applying biaxial strains, the FM SC to antiferromagnetic (AFM) SC transition is revealed at 5% and 3% of biaxial tensile strain. In addition, their high mechanical, dynamical, and thermal stabilities are further verified by phonon dispersion calculations and ab initio molecular dynamics (AIMD) calculations. Their outstanding attributes render the V₃Se₃Y₂ (Y = S, Te) monolayers promising candidates as 2D FM SCs for a wide range of applications. Full article

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11 pages, 5935 KiB

Open AccessArticle

Tailoring Energy Transfer in Mixed Eu/Tb Metal–Organic Frameworks for Ratiometric Temperature Sensing

by Hui Tang, Siyuan Cheng, Zhihui Zhang, Mingyang He, Junfeng Qian and Liang Li

Molecules 2024, 29(16), 3914; https://doi.org/10.3390/molecules29163914 - 19 Aug 2024

Abstract

Eu/Tb metal–organic frameworks (Eu/Tb-MOFs), exhibiting Eu³⁺ and Tb³⁺ emissions, stand out as some of the most fascinating luminescent thermometers. As the relative thermal sensitivity model is limited to its lack of precision for fitting ratio of Eu³⁺ and Tb³⁺ [...] Read more.

Eu/Tb metal–organic frameworks (Eu/Tb-MOFs), exhibiting Eu³⁺ and Tb³⁺ emissions, stand out as some of the most fascinating luminescent thermometers. As the relative thermal sensitivity model is limited to its lack of precision for fitting ratio of Eu³⁺ and Tb³⁺ emissions, accurately predicting the sensing performance of Eu/Tb-MOFs remains a significant challenge. Herein, we report a series of luminescent Eu/Tb-MOF thermometers, Eu_xTb_1−xL, with excellent thermal sensitivity around physiological levels, achieved through the tuning energy transfer from ligands to Eu³⁺ and Tb³⁺ and between the Ln ions. It was found that the singlet lowest-energy excited state (S₁) of the ligand and the higher triplet energy level (T_n) are crucial in the energy transfer processes of ligand→Tb³⁺ and ligand→Eu³⁺. This enables Eu_xTb_1−xL to serve as an effective platform for exploring the impact of these energy transfer processes on the temperature-sensing properties of luminescent Eu/Tb-MOF thermometers. The relative thermal sensitivity is comparable to that of dual-center MOF-based luminescent thermometers operating at physiological levels. This study provides valuable insights into the design of new Eu/Tb thermometers and the accurate prediction of their sensing performance. Full article

(This article belongs to the Special Issue Inorganic/Organic Catalysts: Moving towards an Efficient, Green, and Sustainable Future)

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16 pages, 5967 KiB

Open AccessArticle

Enhanced Tribodegradation of a Tetracycline Antibiotic by Rare-Earth-Modified Zinc Oxide

by Dobrina Ivanova, Hristo Kolev, Bozhidar I. Stefanov and Nina Kaneva

Molecules 2024, 29(16), 3913; https://doi.org/10.3390/molecules29163913 - 19 Aug 2024

Abstract

Tribocatalysis is an emerging advanced oxidation process that utilizes the triboelectric effect, based on friction between dissimilar materials to produce charges that can initiate various catalytic reactions. In this study, pure and rare-earth-modified ZnO powders (La₂O₃, Eu₂O [...] Read more.

Tribocatalysis is an emerging advanced oxidation process that utilizes the triboelectric effect, based on friction between dissimilar materials to produce charges that can initiate various catalytic reactions. In this study, pure and rare-earth-modified ZnO powders (La₂O₃, Eu₂O₃, 2 mol %) were demonstrated as efficient tribocatalysts for the removal of the tetracycline antibiotic doxycycline (DC). While the pure ZnO samples achieved 49% DC removal within 24 h at a stirring rate of 100 rpm, the addition of Eu₂O₃ increased the removal efficiency to 67%, and La₂O₃-modified ZnO powder exhibited the highest removal efficiency, reaching 80% at the same stirring rate. Additionally, increasing the stirring rate to 300 and 500 rpm led to 100% DC removal in the ZnO/La case within 18 h, with the pronounced effect of the stirring rate confirming the tribocatalytic effect. All tribocatalysts exhibited excellent recycling properties, with less than a 3% loss of activity over three cycles. Furthermore, a scavenger assay confirmed the importance of superoxide radical generation for the overall reaction rate. The results of this investigation indicate that the rare-earth-modified ZnO tribocatalysts can effectively utilize mechanical energy to decompose pollutants in contaminated water. Full article

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

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12 pages, 5448 KiB

Open AccessArticle

Investigating the Electrochemical Performance of MnFe₂O₄@xC Nanocomposites as Anode Materials for Sodium-Ion Batteries

by Shi-Wei Liu, Bai-Tong Niu, Bi-Li Lin, Yuan-Ting Lin, Xiao-Ping Chen, Hong-Xu Guo, Yan-Xin Chen and Xiu-Mei Lin

Molecules 2024, 29(16), 3912; https://doi.org/10.3390/molecules29163912 - 19 Aug 2024

Abstract

Transition metal oxides (TMOs) are important anode materials in sodium-ion batteries (SIBs) due to their high theoretical capacities, abundant resources, and cost-effectiveness. However, issues such as the low conductivity and large volume variation of TMO bulk materials during the cycling process result in [...] Read more.

Transition metal oxides (TMOs) are important anode materials in sodium-ion batteries (SIBs) due to their high theoretical capacities, abundant resources, and cost-effectiveness. However, issues such as the low conductivity and large volume variation of TMO bulk materials during the cycling process result in poor electrochemical performance. Nanosizing and compositing with carbon materials are two effective strategies to overcome these issues. In this study, spherical MnFe₂O₄@xC nanocomposites composed of MnFe₂O₄ inner cores and tunable carbon shell thicknesses were successfully prepared and utilized as anode materials for SIBs. It was found that the property of the carbon shell plays a crucial role in tuning the electrochemical performance of MnFe₂O₄@xC nanocomposites and an appropriate carbon shell thickness (content) leads to the optimal battery performance. Thus, compared to MnFe₂O₄@1C and MnFe₂O₄@8C, MnFe₂O₄@4C nanocomposite exhibits optimal electrochemical performance by releasing a reversible specific capacity of around 308 mAh·g⁻¹ at 0.1 A·g⁻¹ with 93% capacity retention after 100 cycles, 250 mAh·g⁻¹ at 1.0 A g⁻¹ with 73% capacity retention after 300 cycles in a half cell, and around 111 mAh·g⁻¹ at 1.0 C when coupled with a Na₃V₂(PO₄)₃ (NVP) cathode in a full SIB cell. Full article

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12 pages, 3199 KiB

Open AccessArticle

Protection of α-Tocopherol from UV-Induced Degradation by Encapsulation into Zein Nanoparticles

by Sanghoon Kim

Molecules 2024, 29(16), 3911; https://doi.org/10.3390/molecules29163911 - 19 Aug 2024

Abstract

Vitamin E is a fat-soluble vitamin with several forms. Among these, α-tocopherol (TOC) is preferentially absorbed and accumulated in humans. In the body, it acts as an antioxidant, helping to protect cells from the damage caused by free radicals. It is an organic [...] Read more.

Vitamin E is a fat-soluble vitamin with several forms. Among these, α-tocopherol (TOC) is preferentially absorbed and accumulated in humans. In the body, it acts as an antioxidant, helping to protect cells from the damage caused by free radicals. It is an organic chemical compound that undergoes degradation upon irradiation with UV light. To protect this bioactive chemical compound from UV light degradation, encapsulation was carried out using zein as a shell material. Due to the unique phase diagram of TOC in aqueous ethanol, the encapsulation efficiency was >99%. The size of encapsulated particles was ~300 nm or smaller, and the thickness of the shell wall was ~30 nm. The presented procedure offers the most simple and efficient encapsulation process that yields edible products. The investigation of the irradiation effect of UV on TOC revealed that the encapsulation effectively blocks UV light and prevents TOC from being degraded. The presented procedure offers an instantaneous and highly efficient encapsulation process, which yields edible products. Full article

(This article belongs to the Special Issue Current Emerging Trends of Extraction and Encapsulation in Food)

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12 pages, 10582 KiB

Open AccessArticle

High-Efficiency Purification and Morphology Regulation of CaSO₄·2H₂O Crystals from Phosphogypsum

by Yang Lei, Yong-Ji Gong, Min He, Liangqun Li, Jun Qin and Yufei Liu

Molecules 2024, 29(16), 3910; https://doi.org/10.3390/molecules29163910 - 19 Aug 2024

Abstract

Phosphogypsum is a solid waste with great environmental stockpile pressure produced by the wet production of phosphoric acid. Although there are various methods to purify and utilize phosphogypsum, the means for environmentally friendly, low energy consumption, and high value-added utilization still need to [...] Read more.

Phosphogypsum is a solid waste with great environmental stockpile pressure produced by the wet production of phosphoric acid. Although there are various methods to purify and utilize phosphogypsum, the means for environmentally friendly, low energy consumption, and high value-added utilization still need to be further explored. Here, CaSO₄·2H₂O crystal was directly purified and regulated from phosphogypsum by using the anti-solvent method. The antisolvent can be adsorbed in the c-axis direction of the crystal and further inhibit the growth rate in this direction, resulting in a change in the morphology of the crystal. By adjusting the polarity and chain length of the anti-solvent, the morphology of CaSO₄·2H₂O crystal can change from butterfly-like flake crystals to hexagonal prism-like crystals. When n-propanol with long chain was used as the anti-solvent, the morphology of the CaSO₄·2H₂O crystal showed a hexagonal prism with a specific surface area of 19.98 m²/g and a Cu²⁺ loading efficiency of 52.67%. The encouraging results open up new possibilities for the application of phosphogypsum. Full article

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13 pages, 1687 KiB

Open AccessArticle

The Synthesis of SNAC Phenolate Salts and the Effect on Oral Bioavailability of Semaglutide

by Tovi Shapira-Furman, Ayala Bar-Hai, Amnon Hoffman and Abraham J. Domb

Molecules 2024, 29(16), 3909; https://doi.org/10.3390/molecules29163909 - 19 Aug 2024

Abstract

Purpose: Sodium N-[8-(2-hydroxybenzoyl)amino]caprylate (SNAC) is a well-known penetration enhancer widely used in commercial applications. This study aims to broaden its properties through a novel strategy of converting it into its phenolate salts. The objective is to investigate the synthesis of SNAC phenolate salts, [...] Read more.

Purpose: Sodium N-[8-(2-hydroxybenzoyl)amino]caprylate (SNAC) is a well-known penetration enhancer widely used in commercial applications. This study aims to broaden its properties through a novel strategy of converting it into its phenolate salts. The objective is to investigate the synthesis of SNAC phenolate salts, specifically SNAC–choline (SNAC-CH), SNAC–sodium (SNAC-Na), and SNAC–phosphatidylcholine (SNAC-PC), and to explore their potential application in improving the oral absorption of semaglutide. Methods: The synthesis of SNAC phenolate salts was confirmed through 1H-NMR, FTIR, and an elemental analysis of C, H, N, and O. In vivo testing was conducted to assess the oral delivery of semaglutide using these synthesized SNAC phenolate salts. Pharmacokinetic (PK) values were measured to evaluate the impact on drug absorption. Results: The synthesis of SNAC phenolate salts (SNAC-CH, SNAC-Na, and SNAC-PC) was successfully achieved under appropriate conditions, and their structures were confirmed using analytical techniques such as IR, NMR, and CHN elemental analysis. The paradigm of their use was evaluated through an oral pharmacokinetic (PK) in vivo study using SNAC phenolate salts, which did not impair the original SNAC PK values. This suggests that this strategy holds promise as a potential new effective enhancer for oral absorption. Conclusions: The utilization of SNAC phenolate salts presents a novel and promising strategy for extending the verity of penetration enhancers’ molecules and properties. Synthesizing phenolate salts represents a new chemical strategy that may open new avenues in molecular development. This approach holds future potential to enhance the oral delivery of peptide drugs like semaglutide without compromising therapeutic efficacy. Overall, it offers significant advancements in the field by providing a potential alternative to injectable peptides through oral delivery systems. Full article

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18 pages, 13263 KiB

Open AccessArticle

Ionic Liquid Catalysis in Cyclic Carbonate Synthesis for the Development of Soybean Oil-Based Non-Isocyanate Polyurethane Foams

by Damian Kiełkiewicz, Agnieszka Siewniak, Rafał Gaida, Małgorzata Greif and Anna Chrobok

Molecules 2024, 29(16), 3908; https://doi.org/10.3390/molecules29163908 - 18 Aug 2024

Abstract

A method for obtaining non-isocyanate polyurethane (NIPU) foams from cyclic carbonate (CC) based on soybean oil was developed. For this purpose, cyclic carbonate was synthesized from epoxidized soybean oil and CO₂ using various ionic liquids (ILs) as catalysts. Among the tested ILs, [...] Read more.

A method for obtaining non-isocyanate polyurethane (NIPU) foams from cyclic carbonate (CC) based on soybean oil was developed. For this purpose, cyclic carbonate was synthesized from epoxidized soybean oil and CO₂ using various ionic liquids (ILs) as catalysts. Among the tested ILs, the highest selectivity (100%) and CC yield (98%) were achieved for 1-ethyl-3-methylimidazolium ([emim]Br). Without any purification, the resulting cyclic carbonate was reacted directly with diethylenetriamine as a model crosslinking agent to produce NIPU foams. It was found that the soybean oil-based CC synthesized with bromide imidazolium ionic liquids exhibited significantly shorter gelling times (8 min 50 s for [emim]Br and 9 min 35 s for [bmim]Br) compared to those obtained with the conventional TBAB catalyst (26 min 15 s). A shorter gelling time is a crucial parameter for the crosslinking process in foams. The obtained foams were subjected to mechanical tests and a morphology analysis. Full article

(This article belongs to the Section Organometallic Chemistry)

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13 pages, 2918 KiB

Open AccessArticle

Fluorescence Turn-Off Ligand for Parallel G-Quadruplexes

by Joanna Nowak-Karnowska, Agata Głuszyńska, Joanna Kosman and Anna Dembska

Molecules 2024, 29(16), 3907; https://doi.org/10.3390/molecules29163907 - 18 Aug 2024

Abstract

Parallel-stranded G-quadruplex structures are found to be common in the human promoter sequences. We tested highly fluorescent 9-methoxyluminarine ligand (9-MeLM) binding interactions with different parallel G-quadruplexes DNA by spectroscopic methods such as fluorescence and circular dichroism (CD) titration as well as UV melting [...] Read more.

Parallel-stranded G-quadruplex structures are found to be common in the human promoter sequences. We tested highly fluorescent 9-methoxyluminarine ligand (9-MeLM) binding interactions with different parallel G-quadruplexes DNA by spectroscopic methods such as fluorescence and circular dichroism (CD) titration as well as UV melting profiles. The results showed that the studied 9-MeLM ligand interacted with the intramolecular parallel G-quadruplexes (G4s) with similar affinity. The binding constants of 9-methoxyluminarine with different parallel G4s were determined. The studies upon oligonucleotides with different flanking sequences on c-MYC G-quadruplex suggest that 9-methoxyluminarine may preferentially interact with 3′end of the c-MYC promoter. The high decrease in 9-MeLM ligand fluorescence upon binding to all tested G4s indicates that 9-methoxyluminarine molecule can be used as a selective fluorescence turn-off probe for parallel G-quadruplexes. Full article

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14 pages, 4499 KiB

Open AccessArticle

Visual Tracking of Hydrogen Sulfide: Application of a Novel Lysosome-Targeted Fluorescent Probe for Bioimaging and Food Safety Assessment

by Likun Liu, Yitong Liu, Haoqing Ren, Peng Hou, Haijun Wang, Jingwen Sun, Lei Liu, Chuan He and Song Chen

Molecules 2024, 29(16), 3906; https://doi.org/10.3390/molecules29163906 - 18 Aug 2024

Abstract

The equilibrium state of hydrogen sulfide (H₂S), a gaseous signaling molecule produced by lysosomal metabolites, in vivo is crucial for cellular function. Abnormal fluctuations in H₂S concentration can interfere with the normal function of lysosomes, which has been closely [...] Read more.

The equilibrium state of hydrogen sulfide (H₂S), a gaseous signaling molecule produced by lysosomal metabolites, in vivo is crucial for cellular function. Abnormal fluctuations in H₂S concentration can interfere with the normal function of lysosomes, which has been closely linked to the pathogenesis of a variety of diseases. In view of this, a novel fluorescent probe Lyso-DPP based on 1,3,5-triarylpyrazolines was developed for the precise detection of H₂S in lysosomes by using the hydrophilic morpholine moiety as a lysosomal targeting unit, and 2,4-dinitroanisole as a fluorescence-quenching and H₂S-responsive unit. The probe cleverly combines the advantages of simple synthesis, sensitive blue fluorescence turn-on with a limit of detection, LOD, of 97.3 nM, good stability, and fast response time (10 min), which makes Lyso-DPP successful in portable monitoring of meat freshness in the form of test strips. Moreover, the excellent biocompatibility and precise targeting capability of the probe Lyso-DPP make it perform well in the monitoring of H₂S in lysosomes, living cells, and zebrafish. This work not only provides new technical tools for food quality control but also paves up new ideas for early diagnosis and treatment of H₂S-related diseases. Full article

(This article belongs to the Special Issue Fluorescent Probes in Biomedical Detection and Imaging)

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30 pages, 2284 KiB

Open AccessReview

Recent Research Progress on the Chemical Constituents, Pharmacology, and Pharmacokinetics of Alpinae oxyphyllae Fructus

by Junfa Liao and Xueying Zhao

Molecules 2024, 29(16), 3905; https://doi.org/10.3390/molecules29163905 - 18 Aug 2024

Abstract

Alpinae oxyphyllae fructus (AOF), the dried mature fruit of Alpinia oxyphylla Miquel of the Zingiberaceae family, shows many special pharmacological effects. In recent years, there has been an abundance of research results on AOF. In this paper, the new compounds isolated from AOF [...] Read more.

Alpinae oxyphyllae fructus (AOF), the dried mature fruit of Alpinia oxyphylla Miquel of the Zingiberaceae family, shows many special pharmacological effects. In recent years, there has been an abundance of research results on AOF. In this paper, the new compounds isolated from AOF since 2018 are reviewed, including terpenes, flavonoids, diarylheptanoids, phenolic acid, sterols, alkanes, fats, etc. The isolation methods that were applied include the microwave-assisted method, response surface method, chiral high-performance liquid chromatography–multiple reaction monitoring–mass spectrometry (HPLC-MRM-MS) analytical method, ultra-high-performance liquid chromatography–quadrupole–electrostatic field orbitrap high-resolution mass spectrometry (UPLC-Orbitrap-HRMS) method, ultra-high-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) method, hot water leaching method, ethanol leaching method, and so on. Additionally, the pharmacological effects of AOF found from 2018 to 2024 are also summarized, including neuroprotection, regulation of metabolic disorders, antioxidant activity, antiapoptosis, antiinflammatory activity, antidiabetic activity, antihyperuricemia, antiaging, antidiuresis, immune regulation, anti-tumor activity, renal protection, hepatoprotection, and anti-asthma. This paper provides a reference for further research on AOF. Full article

(This article belongs to the Special Issue Bioactivity of Natural Compounds: From Plants to Humans)

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32 pages, 7058 KiB

Open AccessReview

Recent Developments in Photoinduced Decarboxylative Acylation of α-Keto Acids

by Shuaiqi Lu, Yilong Xiang, Jingfu Chen and Chao Shu

Molecules 2024, 29(16), 3904; https://doi.org/10.3390/molecules29163904 - 18 Aug 2024

Abstract

Ketones are ubiquitous patterns found in various biological molecules and natural products. In recent years, a number of acylation methods have been developed based on the use of α-oxocarboxylic acids as acyl-transfer reagents, with particular emphasis on the photoinduced decarboxylative acylation of α [...] Read more.

Ketones are ubiquitous patterns found in various biological molecules and natural products. In recent years, a number of acylation methods have been developed based on the use of α-oxocarboxylic acids as acyl-transfer reagents, with particular emphasis on the photoinduced decarboxylative acylation of α-keto acids. This review focuses on the latest advancements in acylation methodologies through the decarboxylation of α-keto acids over the past several years, highlighting their product diversity, selectivity, and applicability. Where possible, the mechanistic rationale is presented, providing a positive outlook for the promising future of this field. Full article

(This article belongs to the Special Issue Recent Progress of Organic Photochemistry)

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18 pages, 5377 KiB

Open AccessArticle

Synthesis and Characterization of Copper(II) and Nickel(II) Complexes with 3-(Morpholin-4-yl)propane-2,3-dione 4-Allylthiosemicarbazone Exploring the Antibacterial, Antifungal and Antiradical Properties

by Ianina Graur, Vasilii Graur, Marina Cadin, Olga Garbuz, Pavlina Bourosh, Elena Melnic, Carolina Lozan-Tirsu, Greta Balan, Victor Tsapkov, Valeriu Fala and Aurelian Gulea

Molecules 2024, 29(16), 3903; https://doi.org/10.3390/molecules29163903 - 17 Aug 2024

Abstract

The eleven new copper(II) and nickel(II) coordination compounds [Cu(L)Br]₂ (1), [Cu(L)Cl] (2), [Cu(L)NO₃] (3), [Ni(L)Cl] (4), [Ni(HL)₂](NO₃)₂ (5), and [Cu(A)(L)]NO₃, where A is [...] Read more.

The eleven new copper(II) and nickel(II) coordination compounds [Cu(L)Br]₂ (1), [Cu(L)Cl] (2), [Cu(L)NO₃] (3), [Ni(L)Cl] (4), [Ni(HL)₂](NO₃)₂ (5), and [Cu(A)(L)]NO₃, where A is 1,10-phenanthroline (6), 2,2′-bipyridine (7), 3,4-dimethylpyridine (8), 3-methylpyridine (9), pyridine (10) and imidazole (11) were synthesized with 3-(morpholin-4-yl)propane-2,3-dione 4-allylthiosemicarbazone (HL). The new thiosemicarbazone was characterized by NMR and FTIR spectroscopy. All the coordination compounds were characterized by elemental analysis and FTIR spectroscopy. Also, the crystal structures of HL and complexes 1, 6, 7, and 11 were determined using single-crystal X-ray diffraction analysis. Complex 1 has a dimeric molecular structure with two bromide bridging ligands, while 6, 7, and 11 are ionic compounds and comprise monomeric complex cations. The studied complexes manifest antibacterial and antifungal activities and also have an antiradical activity that, in many cases, surpasses the activity of trolox, which is used as a standard antioxidant in medicine. Copper complexes 1–3 have very weak antiradical properties (IC₅₀ > 100 µM), but nickel complexes 4–5 are strong antiradicals with IC₅₀ values lower than that of trolox. The mixed ligand copper complexes with additional ligand of N-heteroaromatic base are superior to complexes without these additional ligands. They are 1.4–5 times more active than trolox. Full article

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29 pages, 2253 KiB

Open AccessArticle

Clustering Molecules at a Large Scale: Integrating Spectral Geometry with Deep Learning

by Ömer Akgüller, Mehmet Ali Balcı and Gabriela Cioca

Molecules 2024, 29(16), 3902; https://doi.org/10.3390/molecules29163902 - 17 Aug 2024

Abstract

This study conducts an in-depth analysis of clustering small molecules using spectral geometry and deep learning techniques. We applied a spectral geometric approach to convert molecular structures into triangulated meshes and used the Laplace–Beltrami operator to derive significant geometric features. By examining the [...] Read more.

This study conducts an in-depth analysis of clustering small molecules using spectral geometry and deep learning techniques. We applied a spectral geometric approach to convert molecular structures into triangulated meshes and used the Laplace–Beltrami operator to derive significant geometric features. By examining the eigenvectors of these operators, we captured the intrinsic geometric properties of the molecules, aiding their classification and clustering. The research utilized four deep learning methods: Deep Belief Network, Convolutional Autoencoder, Variational Autoencoder, and Adversarial Autoencoder, each paired with k-means clustering at different cluster sizes. Clustering quality was evaluated using the Calinski–Harabasz and Davies–Bouldin indices, Silhouette Score, and standard deviation. Nonparametric tests were used to assess the impact of topological descriptors on clustering outcomes. Our results show that the DBN + k-means combination is the most effective, particularly at lower cluster counts, demonstrating significant sensitivity to structural variations. This study highlights the potential of integrating spectral geometry with deep learning for precise and efficient molecular clustering. Full article

(This article belongs to the Special Issue Deep Learning in Molecular Science and Technology)

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16 pages, 5195 KiB

Open AccessArticle

Polyurethane Nanocomposite Coatings Coupled with Titanium-Based Conversion Layers for Enhanced Anticorrosion, Icephobic Properties, and Surface Protection

by Shamim Roshan, Reza Jafari and Gelareh Momen

Molecules 2024, 29(16), 3901; https://doi.org/10.3390/molecules29163901 - 17 Aug 2024

Abstract

This study examines the efficacy of icephobic polyurethane nanocomposite coatings in mitigating corrosion on an aluminum substrate. A titanium-based conversion coating is applied to modify the substrate, and the research focuses on optimizing the dual functionalities of icephobicity and anticorrosion within the polyurethane [...] Read more.

This study examines the efficacy of icephobic polyurethane nanocomposite coatings in mitigating corrosion on an aluminum substrate. A titanium-based conversion coating is applied to modify the substrate, and the research focuses on optimizing the dual functionalities of icephobicity and anticorrosion within the polyurethane coatings while ensuring strong substrate adhesion. The coatings are formulated using fluoropolyol, isocyanate, and silica nanoparticles treated with polydimethylsiloxane. Surface properties are analyzed using contact angles, contact angle hysteresis measurements, and atomic force microscopy, and the coatings’ icephobicity is evaluated through differential scanning calorimetry, freezing time delay, ice adhesion under impact and non-impact conditions, and ice accretion tests. The corrosion resistance and adhesive strength of the coatings are assessed using electrochemical impedance spectroscopy and cross-cut tests, respectively. Increasing the concentration of silica nanoparticles to 10 wt.% increases contact angles to 167°, although the 4 wt.% coating produces the lowest contact angle hysteresis (3° ± 0.5°) and ice nucleation temperature (−23 °C). The latter coating is then applied to a substrate pretreated with a titanium/cerium-based conversion coating. This prepared surface maintains an ice adhesion of about 15 kPa after 15 icing/de-icing cycles and provides approximately 90 days of surface protection (|Z|_lf = 1.6 × 10⁹ Ω·cm²). Notably, the impedance value exceeds that of untreated substrates, underscoring the effectiveness of the titanium/cerium-based conversion coating in enhancing both corrosion resistance and coating adhesion to the substrate. Full article

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35 pages, 2087 KiB

Open AccessReview

Analytical Methods for the Determination of Pharmaceuticals and Personal Care Products in Solid and Liquid Environmental Matrices: A Review

by Abdulmalik M. Alqarni

Molecules 2024, 29(16), 3900; https://doi.org/10.3390/molecules29163900 - 17 Aug 2024

Abstract

Among the various compounds regarded as emerging contaminants (ECs), pharmaceuticals and personal care products (PPCPs) are of particular concern. Their continuous release into the environment has a negative global impact on human life. This review summarizes the sources, occurrence, persistence, consequences of exposure, [...] Read more.

Among the various compounds regarded as emerging contaminants (ECs), pharmaceuticals and personal care products (PPCPs) are of particular concern. Their continuous release into the environment has a negative global impact on human life. This review summarizes the sources, occurrence, persistence, consequences of exposure, and toxicity of PPCPs, and evaluates the various analytical methods used in the identification and quantification of PPCPs in a variety of solid and liquid environmental matrices. The current techniques of choice for the analysis of PPCPs are state-of-the-art liquid chromatography coupled to mass spectrometry (LC-MS) or tandem mass spectrometry (LC-MS²). However, the complexity of the environmental matrices and the trace levels of micropollutants necessitate the use of advanced sample treatments before these instrumental analyses. Solid-phase extraction (SPE) with different sorbents is now the predominant method used for the extraction of PPCPs from environmental samples. This review also addresses the ongoing analytical method challenges, including sample clean-up and matrix effects, focusing on the occurrence, sample preparation, and analytical methods presently available for the determination of environmental residues of PPCPs. Continuous development of innovative analytical methods is essential for overcoming existing limitations and ensuring the consistency and diversity of analytical methods used in investigations of environmental multi-class compounds. Full article

(This article belongs to the Special Issue Advanced Analytical Techniques for the Detection and Quantification of Emerging Contaminants)

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