Molecules

16 pages, 5347 KiB

Open AccessArticle

The Discovery, Molecular Cloning, and Characterization of Dextransucrase LmDexA and Its Active Truncated Mutant from Leuconostoc mesenteroides NN710

by Xiaoqiong Zuo, Lixia Pan, Wenchao Zhang, Jing Zhu, Yan Qin, Xiuying Xu and Qingyan Wang

Molecules 2024, 29(13), 3242; https://doi.org/10.3390/molecules29133242 - 8 Jul 2024

Viewed by 1021

Abstract

Dextransucrases play a crucial role in the production of dextran from economical sucrose; therefore, there is a pressing demand to explore novel dextransucrases with better performance. This study characterized a dextransucrase enzyme, LmDexA, which was identified from the Leuconostoc mesenteroides NN710. This [...] Read more.

Dextransucrases play a crucial role in the production of dextran from economical sucrose; therefore, there is a pressing demand to explore novel dextransucrases with better performance. This study characterized a dextransucrase enzyme, LmDexA, which was identified from the Leuconostoc mesenteroides NN710. This bacterium was isolated from the soil of growing dragon fruit in Guangxi province, China. We successfully constructed six different N-terminal truncated variants through sequential analysis. Additionally, a truncated variant, ΔN190LmDexA, was constructed by removing the 190 amino acids fragment from the N-terminal. This truncated variant was then successfully expressed heterologously in Escherichia coli and purified. The purified ΔN190LmDexA demonstrated optimal hydrolysis activity at a pH of 5.6 and a temperature of 30 °C. Its maximum specific activity was measured to be 126.13 U/mg, with a K_m of 13.7 mM. Results demonstrated a significant improvement in the heterologous expression level and total enzyme activity of ΔN190LmDexA. ΔN190LmDexA exhibited both hydrolytic and transsaccharolytic enzymatic activities. When sucrose was used as the substrate, it primarily produced high-molecular-weight dextran (>400 kDa). However, upon the addition of maltose as a receptor, it resulted in the production of a significant amount of oligosaccharides. Our results can provide valuable information for enhancing the characteristics of recombinant dextransucrase and potentially converting sucrose into high-value-added dextran and oligosaccharides. Full article

► Show Figures

Figure 1

13 pages, 3158 KiB

Open AccessArticle

Evaluation of Terpene Decomposition in Kaffir Lime Juice during Storage Using Gas Chromatography–Mass Spectrometry and Proton Transfer Reaction–Mass Spectrometry

by Martyna Lubinska-Szczygeł, Żaneta Polkowska, Blanka Tobolkova, Tomasz Majchrzak, Martin Polovka, Parichart Promchote and Shela Gorinstein

Molecules 2024, 29(13), 3241; https://doi.org/10.3390/molecules29133241 - 8 Jul 2024

Viewed by 1104

Abstract

Kaffir lime juice, often treated as production waste, can be a good source of terpenes. These compounds undergo various decomposition processes under the influence of external factors, especially during transportation and storage. In this paper, it was possible to monitor changes in the [...] Read more.

Kaffir lime juice, often treated as production waste, can be a good source of terpenes. These compounds undergo various decomposition processes under the influence of external factors, especially during transportation and storage. In this paper, it was possible to monitor changes in the terpene profile of kaffir lime juice under different storage conditions, namely, 4 °C, 20 °C, and 35 °C. The identification of key decomposition products was achieved using gas chromatography–mass spectrometry (GC–MS) and a data mining protocol. It was followed by tracing those products in different storage conditions using a high-throughput proton transfer reaction mass spectrometry (PTR–MS) approach. Based on our findings, degradation pathways were presented, showing that the main products resulting from storage are p-cymene, p-cymenene, terpinene-4-ol, and α-terpineol. It was shown that conversion to p-cymenene occurs after 5 days of storage. Terpinene-4-ol and α-terpineol were found to be the final products of the conversion at all temperatures. Changes in the composition of terpenes are important from the point of view of their bioactive properties. Full article

► Show Figures

Graphical abstract

11 pages, 2215 KiB

Open AccessArticle

Enhancing Performance of Organic Pollutant Degradation via Building Heterojunctions with ZnO Nanowires and Na Doped Conjugated 2,4,6-Triaminopyrimidin-g-C₃N₄

by Ziyi Liu, Zixin Ruan, Xiaojie Yang, Yaqiong Huang and Jun Xing

Molecules 2024, 29(13), 3240; https://doi.org/10.3390/molecules29133240 - 8 Jul 2024

Viewed by 825

Abstract

Organic pollutants were one of the main sources of environmental pollutants. The degradation of organic pollutants through photocatalytic technology was one of the effective solutions. By preparing zinc oxide(ZnO) nanowires modified with sodium-doped conjugated 2,4,6-triaminopyrimidin-g-C₃N₄ (NaTCN) heterojunction (ZnO/NaTCN), the photocatalytic [...] Read more.

Organic pollutants were one of the main sources of environmental pollutants. The degradation of organic pollutants through photocatalytic technology was one of the effective solutions. By preparing zinc oxide(ZnO) nanowires modified with sodium-doped conjugated 2,4,6-triaminopyrimidin-g-C₃N₄ (NaTCN) heterojunction (ZnO/NaTCN), the photocatalytic performance of NaTCN modified with different ratios of ZnO was systematically studied. The photocatalytic performance was studied through the degradation performance of methyl blue (MB) dye. The results showed that 22.5 wt% ZnO/NaTCN had the best degradation effect on MB dye. The degradation rate of MB reached 98.54% in 70 min. After three cycles, it shows good cycling stability (degradation rate is 96.99%) for dye degradation. It was found that there are two types of active species: ·OH and h⁺, of which h⁺ is the main active species produced by photocatalytic degradation of dyes. The excellent degradation performance was attributed to the fact that ZnO facilitated the extraction and transport of photogenerated carriers. The doping of sodium facilitated charge transfer. The NaTCN conjugated system promoted the extraction and transfer of photogenerated carriers. It provided guidance for designing efficient composite catalysts for use in other renewable energy fields. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis in Environmental Application)

► Show Figures

Figure 1

22 pages, 3957 KiB

Open AccessArticle

Encapsulation of Imidazole into Ce-Modified Mesoporous KIT-6 for High Anhydrous Proton Conductivity

by Agata Tabero, Aldona Jankowska, Adam Ostrowski, Ewa Janiszewska, Jolanta Kowalska-Kuś, Agnieszka Held and Stanisław Kowalak

Molecules 2024, 29(13), 3239; https://doi.org/10.3390/molecules29133239 - 8 Jul 2024

Viewed by 804

Abstract

Imidazole molecules entrapped in porous materials can exhibit high and stable proton conductivity suitable for elevated temperature (>373 K) fuel cell applications. In this study, new anhydrous proton conductors based on imidazole and mesoporous KIT-6 were prepared. To explore the impact of the [...] Read more.

Imidazole molecules entrapped in porous materials can exhibit high and stable proton conductivity suitable for elevated temperature (>373 K) fuel cell applications. In this study, new anhydrous proton conductors based on imidazole and mesoporous KIT-6 were prepared. To explore the impact of the acidic nature of the porous matrix on proton conduction, a series of KIT-6 materials with varying Si/Al ratios and pure silica materials were synthesized. These materials were additionally modified with cerium atoms to enhance their Brønsted acidity. TPD-NH₃ and esterification model reaction confirmed that incorporating aluminum into the silica framework and subsequent modification with cerium atoms generated additional acidic sites. UV-Vis and XPS identified the presence of Ce³⁺ and Ce⁴⁺ in the KIT-6 materials, indicating that high-temperature treatment after cerium introduction may lead to partial cerium incorporation into the framework. EIS studies demonstrated that dispersing imidazole within the KIT-6 matrices resulted in composites showing high proton conductivity over a wide temperature range (300–393 K). The presence of weak acidic centers, particularly Brønsted sites, was found to be beneficial for achieving high conductivity. Cerium-modified composites exhibited conductivity surpassing that of molten imidazole, with the highest conductivity (1.13 × 10⁻³ S/cm at 393 K) recorded under anhydrous conditions for Ce-KIT-6. Furthermore, all tested composites maintained high stability over multiple heating and cooling cycles. Full article

(This article belongs to the Special Issue Zeolites and Porous Materials: Synthesis, Properties and Applications)

► Show Figures

Graphical abstract

16 pages, 11736 KiB

Open AccessArticle

Exploring the Structural and Electronic Properties of Niobium Carbide Clusters: A Density Functional Theory Study

by Hui-Fang Li, Huai-Qian Wang and Yu-Kun Zhang

Molecules 2024, 29(13), 3238; https://doi.org/10.3390/molecules29133238 - 8 Jul 2024

Viewed by 842

Abstract

This paper systematically investigates the structure, stability, and electronic properties of niobium carbide clusters, Nb_mC_n (m = 5, 6; n = 1–7), using density functional theory. Nb₅C₂ and Nb₅C₆ possess higher dissociation energies and [...] Read more.

This paper systematically investigates the structure, stability, and electronic properties of niobium carbide clusters, Nb_mC_n (m = 5, 6; n = 1–7), using density functional theory. Nb₅C₂ and Nb₅C₆ possess higher dissociation energies and second-order difference energies, indicating that they have higher thermodynamic stability. Moreover, ab initio molecular dynamics (AIMD) simulations are used to demonstrate the thermal stability of these structures. The analysis of the density of states indicates that the molecular orbitals of Nb_mC_n (m = 5, 6; n = 1–7) are primarily contributed by niobium atoms, with carbon atoms having a smaller contribution. The composition of the frontier molecular orbitals reveals that niobium atoms contribute approximately 73.1% to 99.8% to Nb_mC_n clusters, while carbon atoms contribute about 0.2% to 26.9%. Full article

(This article belongs to the Topic Advances in Computational Materials Sciences)

► Show Figures

Graphical abstract

15 pages, 1750 KiB

Open AccessReview

High-Throughput Mining of Novel Compounds from Known Microbes: A Boost to Natural Product Screening

by Surya Nandan Meena, Anna Wajs-Bonikowska, Savita Girawale, Md Imran, Preethi Poduval and Kisan M. Kodam

Molecules 2024, 29(13), 3237; https://doi.org/10.3390/molecules29133237 - 8 Jul 2024

Viewed by 1381

Abstract

Advanced techniques can accelerate the pace of natural product discovery from microbes, which has been lagging behind the drug discovery era. Therefore, the present review article discusses the various interdisciplinary and cutting-edge techniques to present a concrete strategy that enables the high-throughput screening [...] Read more.

Advanced techniques can accelerate the pace of natural product discovery from microbes, which has been lagging behind the drug discovery era. Therefore, the present review article discusses the various interdisciplinary and cutting-edge techniques to present a concrete strategy that enables the high-throughput screening of novel natural compounds (NCs) from known microbes. Recent bioinformatics methods revealed that the microbial genome contains a huge untapped reservoir of silent biosynthetic gene clusters (BGC). This article describes several methods to identify the microbial strains with hidden mines of silent BGCs. Moreover, antiSMASH 5.0 is a free, accurate, and highly reliable bioinformatics tool discussed in detail to identify silent BGCs in the microbial genome. Further, the latest microbial culture technique, HiTES (high-throughput elicitor screening), has been detailed for the expression of silent BGCs using 500–1000 different growth conditions at a time. Following the expression of silent BGCs, the latest mass spectrometry methods are highlighted to identify the NCs. The recently emerged LAESI-IMS (laser ablation electrospray ionization-imaging mass spectrometry) technique, which enables the rapid identification of novel NCs directly from microtiter plates, is presented in detail. Finally, various trending ‘dereplication’ strategies are emphasized to increase the effectiveness of NC screening. Full article

► Show Figures

Graphical abstract

18 pages, 7519 KiB

Open AccessReview

Recent Progress in Solid-State Room Temperature Afterglow Based on Pure Organic Small Molecules

by Xin Shen, Wanhua Wu and Cheng Yang

Molecules 2024, 29(13), 3236; https://doi.org/10.3390/molecules29133236 - 8 Jul 2024

Cited by 1 | Viewed by 1113

Abstract

Organic room temperature afterglow (ORTA) can be categorized into two key mechanisms: continuous thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), both of which involve a triplet excited state. However, triplet excited states are easily quenched by non-radiative transitions due to oxygen [...] Read more.

Organic room temperature afterglow (ORTA) can be categorized into two key mechanisms: continuous thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), both of which involve a triplet excited state. However, triplet excited states are easily quenched by non-radiative transitions due to oxygen and molecular vibrations. Solid-phase systems provide a conducive environment for triplet excitons due to constrained molecular motion and limited oxygen permeation within closely packed molecules. The stimulated triplet state tends to release energy through radiative transitions. Despite numerous reports on RTP in solid-phase systems in recent years, the complexity of these systems precludes the formulation of a universal theory to elucidate the underlying principles. Several strategies for achieving ORTA luminescence in the solid phase have been developed, encompassing crystallization, polymer host-guest doping, and small molecule host-guest doping. Many of these systems exhibit luminescent responses to various physical stimuli, including light stimulation, mechanical stimuli, and solvent vapor exposure. The appearance of these intriguing luminescent phenomena in solid-phase systems underscores their significant potential applications in areas such as light sensing, biological imaging, and information security. Full article

(This article belongs to the Special Issue Chemical Insights in Photofunctional Organic Compounds—a Themed Issue Dedicated to Professor Vaidhyanathan Ramamurthy)

► Show Figures

Figure 1

15 pages, 10719 KiB

Open AccessArticle

Widely Targeted Metabolomic Analysis Reveals the Improvement in Panax notoginseng Triterpenoids Triggered by Arbuscular Mycorrhizal Fungi via UPLC–ESI–MS/MS

by Xing-Kai Zhang, Yue Wu, Xian-Nv Long, Xiao-Xu You, Di Chen, Yue Bi, Sen He and Guan-Hua Cao

Molecules 2024, 29(13), 3235; https://doi.org/10.3390/molecules29133235 - 8 Jul 2024

Viewed by 1081

Abstract

Panax notoginseng is a highly valued perennial medicinal herb in China and is widely used in clinical treatments. The main purpose of this study was to elucidate the changes in the composition of P. notoginseng saponins (PNSs), which are the main bioactive substances, [...] Read more.

Panax notoginseng is a highly valued perennial medicinal herb in China and is widely used in clinical treatments. The main purpose of this study was to elucidate the changes in the composition of P. notoginseng saponins (PNSs), which are the main bioactive substances, triggered by arbuscular mycorrhizal fungi (AMF) via ultrahigh-performance liquid chromatography–electrospray ionization–tandem mass spectrometry (UPLC–ESI–MS/MS). A total of 202 putative terpenoid metabolites were detected, of which 150 triterpene glycosides were identified, accounting for 74.26% of the total. Correlation analysis, principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS–DA) of the metabolites revealed that the samples treated with AMF (group Ce) could be clearly separated from the CK samples. In total, 49 differential terpene metabolites were identified between the Ce and CK groups, of which 38 and 11 metabolites were upregulated and downregulated, respectively, and most of the upregulated differentially abundant metabolites were mainly triterpene glycosides. The relative abundances of the two major notoginsenosides (MNs), ginsenosides Rd and Re, and 13 rare notoginsenosides (RNs), significantly increased. The differential saponins, especially RNs, were more easily clustered into one branch and had a high positive correlation. It could be concluded that the biosynthesis and accumulation of some RNs share the same pathways as those triggered by AMF. This study provides a new way to obtain more notoginsenoside resources, particularly RNs, and sheds new light on the scientization and rationalization of the use of AMF agents in the ecological planting of medicinal plants. Full article

(This article belongs to the Special Issue Chromatography and Extraction Techniques for Chemical Applications)

► Show Figures

Graphical abstract

24 pages, 9313 KiB

Open AccessReview

In Silico Methods for the Discovery of Kv7.2/7.3 Channels Modulators: A Comprehensive Review

by Claudio Stagno, Francesca Mancuso, Tania Ciaglia, Carmine Ostacolo, Anna Piperno, Nunzio Iraci and Nicola Micale

Molecules 2024, 29(13), 3234; https://doi.org/10.3390/molecules29133234 - 8 Jul 2024

Viewed by 1216

Abstract

The growing interest in Kv7.2/7.3 agonists originates from the involvement of these channels in several brain hyperexcitability disorders. In particular, Kv7.2/7.3 mutants have been clearly associated with epileptic encephalopathies (DEEs) as well as with a spectrum of focal epilepsy disorders, often associated with [...] Read more.

The growing interest in Kv7.2/7.3 agonists originates from the involvement of these channels in several brain hyperexcitability disorders. In particular, Kv7.2/7.3 mutants have been clearly associated with epileptic encephalopathies (DEEs) as well as with a spectrum of focal epilepsy disorders, often associated with developmental plateauing or regression. Nevertheless, there is a lack of available therapeutic options, considering that retigabine, the only molecule used in clinic as a broad-spectrum Kv7 agonist, has been withdrawn from the market in late 2016. This is why several efforts have been made both by both academia and industry in the search for suitable chemotypes acting as Kv7.2/7.3 agonists. In this context, in silico methods have played a major role, since the precise structures of different Kv7 homotetramers have been only recently disclosed. In the present review, the computational methods used for the design of Kv.7.2/7.3 small molecule agonists and the underlying medicinal chemistry are discussed in the context of their biological and structure-function properties. Full article

(This article belongs to the Special Issue Computational Drug Discovery: Methods and Applications)

► Show Figures

Graphical abstract

21 pages, 9102 KiB

Open AccessArticle

The Recyclability of Fire-Retarded Biobased Polyamide 11 (PA11) Composites Reinforced with Basalt Fibers (BFs): The Influence of Reprocessing on Structure, Properties, and Fire Behavior

by Mateusz Barczewski, Aleksander Hejna, Jacek Andrzejewski, Joanna Aniśko, Adam Piasecki, Adrian Mróz, Zaida Ortega, Daria Rutkowska and Kamila Sałasińska

Molecules 2024, 29(13), 3233; https://doi.org/10.3390/molecules29133233 - 8 Jul 2024

Cited by 1 | Viewed by 1395

Abstract

The growing requirements regarding the safety of using polymers and their composites are related to the emergence of more effective, sustainable, and hazardous-limited fire retardants (FRs). Significant amounts of FRs are usually required to effectively affect a polymer’s burning behavior, while the knowledge [...] Read more.

The growing requirements regarding the safety of using polymers and their composites are related to the emergence of more effective, sustainable, and hazardous-limited fire retardants (FRs). Significant amounts of FRs are usually required to effectively affect a polymer’s burning behavior, while the knowledge of their recycling potential is still insufficient. At the same time, concerns are related not only to the reduced effectiveness of flame retardancy but also, above all, to the potential deterioration of mechanical properties caused by the degradation of temperature-affected additives under processing conditions. This study describes the impact of the four-time reprocessing of bio-based polyamide 11 (PA11) modified with an intumescent flame-retardant (IFR) system composed of ammonium polyphosphate (APP), melamine cyanurate (MC), and pentaerythritol (PER) and its composites containing additional short basalt fibers (BFs). Composites manufactured via twin-screw extrusion were subjected to four reprocessing cycles using injection molding. A comprehensive analysis of their structural, mechanical, and fire behavior changes in each cycle was conducted. The obtained results confirmed the safety of using the proposed fire-retarded polyamide and its composites while reprocessing under the recommended process parameters without the risk of significant changes in the structure. The partial increase in flammability of reprocessed PA-based materials caused mainly by polymer degradation has been described. Full article

(This article belongs to the Special Issue Recent Advances in Flame Retardant Polymeric Materials)

► Show Figures

Figure 1

14 pages, 2047 KiB

Open AccessArticle

Assessing the Effects of Thiazole-Carboxamide Derivatives on the Biophysical Properties of AMPA Receptor Complexes as a Potential Neuroprotective Agent

by Mohammad Qneibi, Mohammed Hawash, Sosana Bdir, Mohammad Bdair and Samia Ammar Aldwaik

Molecules 2024, 29(13), 3232; https://doi.org/10.3390/molecules29133232 - 8 Jul 2024

Viewed by 1187

Abstract

An optimal balance between excitatory and inhibitory transmission in the central nervous system provides essential neurotransmission for good functioning of the neurons. In the neurology field, a disturbed balance can lead to neurological diseases like epilepsy, Alzheimer’s, and Autism. One of the critical [...] Read more.

An optimal balance between excitatory and inhibitory transmission in the central nervous system provides essential neurotransmission for good functioning of the neurons. In the neurology field, a disturbed balance can lead to neurological diseases like epilepsy, Alzheimer’s, and Autism. One of the critical agents mediating excitatory neurotransmission is α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptors, which are concerned with synaptic plasticity, memory, and learning. An imbalance in neurotransmission finally results in excitotoxicity and neurological pathologies that should be corrected through specific compounds. Hence, the current study will prove to be an evaluation of new thiazole-carboxamide derivatives concerning AMPAR-modulating activity and extended medicinal potential. In the current project, five previously synthesized thiazole-carboxamide derivatives, i.e., TC-1 to TC-5, were used to interact with the AMPARs expressed in HEK293T cells, which overexpress different subunits of the AMPAR. Patch-clamp analysis was carried out while the effect of the drugs on AMPAR-mediated currents was followed with a particular emphasis on the kinetics of inhibition, desensitization, and deactivation. All tested TC compounds, at all subunits, showed potent inhibition of AMPAR-mediated currents, with TC-2 being the most powerful for all subunits. These compounds shifted the receptor kinetics efficiently, mainly enhancing the deactivation rates, and hence acted as a surrogate for their neuroprotective potentials. Additionally, recently published structure–activity relationship studies identified particular substituent groups as necessary for improving the pharmacologic profiles of these compounds. In this regard, thiazole-carboxamide derivatives, particularly those classified as TC-2, have become essential negative allosteric modulators of AMPAR function and potential therapeutics in neurological disturbances underlain by the dysregulation of excitatory neurotransmission. Given their therapeutic effectiveness and safety profiles, these in vivo studies need to be further validated, although computational modeling can be further developed for drug design and selectivity. This will open possibilities for new drug-like AMPAR negative allosteric modulators with applications at the clinical level toward neurology. Full article

(This article belongs to the Special Issue Synthesis of Bioactive Compounds: Volume II)

► Show Figures

Graphical abstract

20 pages, 2359 KiB

Open AccessArticle

Antiviral and Cytotoxic Activities of Ilex aquifolium Silver Queen in the Context of Chemical Profiling of Two Ilex Species

by Natalia Pachura, Maciej Włodarczyk, Barbara Bażanów, Aleksandra Pogorzelska, Tomasz Gębarowski, Robert Kupczyński and Antoni Szumny

Molecules 2024, 29(13), 3231; https://doi.org/10.3390/molecules29133231 - 8 Jul 2024

Viewed by 1673

Abstract

The leaves of Ilex paraguariensis (known as Yerba mate), used as a popular beverage, are a very well-recognized plant material with various biological activities, including analeptic (because of caffeine), anti-obesity (phenolics, saponins), antimicrobial, and antiviral (phenolics, saponins). Here, the chemical compositions of the [...] Read more.

The leaves of Ilex paraguariensis (known as Yerba mate), used as a popular beverage, are a very well-recognized plant material with various biological activities, including analeptic (because of caffeine), anti-obesity (phenolics, saponins), antimicrobial, and antiviral (phenolics, saponins). Here, the chemical compositions of the leaves of two European Ilex species (× meserveae and aquifolium) with three varieties each were investigated. The terpenoid, saponin, and polyphenolic fractions were submitted for LC-MS or GC-MS analysis against a standard Mate leaf. In addition, the aroma profiles of all the species were analysed using HS-SPME-Arrow prior to GC-MS analysis. All fractions were subjected to antiviral and cytotoxic assays. We found 86 compounds in all accessions, with limonene, linalool, and p-cymene being predominant. There were minor similarities between the volatile compositions of the European and South American species. We found ursolic and oleanolic acid to be the main compounds in the terpenoid fraction. Mono-caffeoylquinic acids and di-caffeoylquinic acids were the main constituents of the polar fractions. About 180 compounds from the saponin group were tentatively identified, of which 9 and 3 were selected as distinctive markers for I. meserveae and I. aquifolium, respectively. Based on chemical screening, I. aquifolium Silver Queen was chosen as the source of terpenoid and saponin fractions and polyphenol extracts. The most substantial inhibition of cancer cell growth was observed with saponin in the case of the MCF7 (human breast cancer) cell line, while for LoVo and L929 cell lines (human colorectal cancer and reference mouse fibroblasts), it was slightly weaker. These results should be analysed further as a promising chemoprevention of colorectal and gastrointestinal cancers. Saponin and polyphenolic extracts exhibited similar activities against HSV-1 and HAdV-5, with 4-log reduction in virus titres. This study focuses our attention on a field of potential antiviral formulations derived from European holly. Full article

(This article belongs to the Special Issue Chemical and Biological Research on Bioactive Natural Products)

► Show Figures

Figure 1

39 pages, 7169 KiB

Open AccessReview

Review of the Interfacial Structure and Properties of Surfactants in Petroleum Production and Geological Storage Systems from a Molecular Scale Perspective

by Jihui Jia, Shu Yang, Jingwei Li, Yunfeng Liang, Rongjuan Li, Takeshi Tsuji, Ben Niu and Bo Peng

Molecules 2024, 29(13), 3230; https://doi.org/10.3390/molecules29133230 - 8 Jul 2024

Cited by 1 | Viewed by 1952

Abstract

Surfactants play a crucial role in tertiary oil recovery by reducing the interfacial tension between immiscible phases, altering surface wettability, and improving foam film stability. Oil reservoirs have high temperatures and high pressures, making it difficult and hazardous to conduct lab experiments. In [...] Read more.

Surfactants play a crucial role in tertiary oil recovery by reducing the interfacial tension between immiscible phases, altering surface wettability, and improving foam film stability. Oil reservoirs have high temperatures and high pressures, making it difficult and hazardous to conduct lab experiments. In this context, molecular dynamics (MD) simulation is a valuable tool for complementing experiments. It can effectively study the microscopic behaviors (such as diffusion, adsorption, and aggregation) of the surfactant molecules in the pore fluids and predict the thermodynamics and kinetics of these systems with a high degree of accuracy. MD simulation also overcomes the limitations of traditional experiments, which often lack the necessary temporal–spatial resolution. Comparing simulated results with experimental data can provide a comprehensive explanation from a microscopic standpoint. This article reviews the state-of-the-art MD simulations of surfactant adsorption and resulting interfacial properties at gas/oil–water interfaces. Initially, the article discusses interfacial properties and methods for evaluating surfactant-formed monolayers, considering variations in interfacial concentration, molecular structure of the surfactants, and synergistic effect of surfactant mixtures. Then, it covers methods for characterizing microstructure at various interfaces and the evolution process of the monolayers’ packing state as a function of interfacial concentration and the surfactants’ molecular structure. Next, it examines the interactions between surfactants and the aqueous phase, focusing on headgroup solvation and counterion condensation. Finally, it analyzes the influence of hydrophobic phase molecular composition on interactions between surfactants and the hydrophobic phase. This review deepened our understanding of the micro-level mechanisms of oil displacement by surfactants and is beneficial for screening and designing surfactants for oil field applications. Full article

(This article belongs to the Topic Energy Extraction and Processing Science)

► Show Figures

Figure 1

15 pages, 5193 KiB

Open AccessArticle

Hydrous Molybdenum Oxide Coating of Zinc Metal Anode via the Facile Electrodeposition Strategy and Its Performance Improvement Mechanisms for Aqueous Zinc−Ion Batteries

by Jianwei Yuan, Yutao Shi, Weibai Bian, Huaren Wu, Yingjun Chen, Chengcheng Zhou, Xiaohui Chen, Wei Zhang and Hailin Shen

Molecules 2024, 29(13), 3229; https://doi.org/10.3390/molecules29133229 - 8 Jul 2024

Viewed by 1123

Abstract

Aqueous zinc−ion batteries (ZIBs) are widely recognized as highly promising energy storage devices because of their inherent characteristics, including superior safety, affordability, eco−friendliness, and various other benefits. However, the significant corrosion of the zinc metal anode, side reactions occurring between the anode and [...] Read more.

Aqueous zinc−ion batteries (ZIBs) are widely recognized as highly promising energy storage devices because of their inherent characteristics, including superior safety, affordability, eco−friendliness, and various other benefits. However, the significant corrosion of the zinc metal anode, side reactions occurring between the anode and electrolyte, and the formation of zinc dendrites significantly hinder the practical utilization of ZIBs. Herein, we utilized an electrodeposition method to apply a unique hydrous molybdenum oxide (HMoO_x) layer onto the surface of the zinc metal anode, aiming to mitigate its corrosion and side reactions during the process of zinc deposition and stripping. In addition, the HMoO_x layer not only improved the hydrophilicity of the zinc anode, but also adjusted the migration of Zn²⁺, thus facilitating the uniform deposition of Zn²⁺ to reduce dendrite formation. A symmetrical cell with the HMoO_x−Zn anode displayed reduced−voltage hysteresis (80 mV at 2.5 mA/cm²) and outstanding cycle stability after 3000 cycles, surpassing the performance of the uncoated Zn anode. Moreover, the HMoO_x−Zn anode coupled with a γ−MnO₂ cathode created a considerably more stable rechargeable full battery compared to the bare Zn anode. The HMoO_x−Zn||γ−MnO₂ full cell also displayed excellent cycling stability with a charge/discharge−specific capacity of 129/133 mAh g⁻¹ after 300 cycles. In summary, this research offers a straightforward and advantageous approach that can significantly contribute to the future advancements in rechargeable ZIBs. Full article

► Show Figures

Graphical abstract

13 pages, 3483 KiB

Open AccessArticle

The Synergetic Reduction of the Condensation Degree of Dissolved Lignin (DL) during the Refining Process of Wheat Straw Biomass Based on the MA/O₃ System

by Xiuguang Chen, Zhulan Liu, Zhenyu Zhou, Renai Li, Lizi Li and Yunfeng Cao

Molecules 2024, 29(13), 3228; https://doi.org/10.3390/molecules29133228 - 8 Jul 2024

Viewed by 853

Abstract

Lignin, a natural pol2ymer with a complex structure that is difficult to separate, is prone to C-C bond condensation during the separation process. To reduce the condensation of lignin, here, a novel method is proposed for separating the components by using a combination [...] Read more.

Lignin, a natural pol2ymer with a complex structure that is difficult to separate, is prone to C-C bond condensation during the separation process. To reduce the condensation of lignin, here, a novel method is proposed for separating the components by using a combination of maleic acid (MA)/ozone (O₃) to co-treat wheat straw. The removal of lignin, glucan, and xylan was 38.07 ± 0.2%, 31.44 ± 0.1%, and 71.98 ± 0.1%, respectively, under the conditions of ball-milling of wheat straw for 6 h, reaction temperature of 60 °C, and O₃ holding time of 9 min. Lignin-rich solutions were collected to extract the dissolved lignin (DL) after washing the treated samples. The DL obtained under MA/O₃ conditions had a carboxyl group (-COOH) content of 2.96 mmol/g. The carboxyl group of MA underwent esterification with the hydroxyl group (-OH) at the γ position of lignin and O₃ reacted on the positions of the lignin side chain or the phenolic ring, resulting in a break in the side chain and the opening of the phenolic ring to introduce the carboxyl group. The 2D-HSQC-NMR results revealed that the phenolic ring-opening reaction of lignin in the presence of O₃ was essentially free of β-β and β-5 condensation bonds. Full article

► Show Figures

Figure 1

12 pages, 1680 KiB

Open AccessArticle

Bismuth(III)-Catalyzed Regioselective Selenation of Indoles with Diaryl Diselenides: Synthesis of 3-Selanylindoles

by Mio Matsumura, Airi Umeda, Yuika Sumi, Naoki Aiba, Yuki Murata and Shuji Yasuike

Molecules 2024, 29(13), 3227; https://doi.org/10.3390/molecules29133227 - 8 Jul 2024

Viewed by 883

Abstract

Heterocyclic aryl selenides have recently attracted considerable research interest owing to their applications in biological and pharmaceutical fields. Herein, we describe a simple and general synthesis of 3-selanylindoles via a novel regioselective C–H selenation of indoles using a bismuth reagent as a catalyst. [...] Read more.

Heterocyclic aryl selenides have recently attracted considerable research interest owing to their applications in biological and pharmaceutical fields. Herein, we describe a simple and general synthesis of 3-selanylindoles via a novel regioselective C–H selenation of indoles using a bismuth reagent as a catalyst. The reactions of indoles with diselenides in the presence of 10 mol% BiI₃ at 100 °C in DMF afforded the corresponding 3-selanylindoles in moderate-to-excellent yields. The reaction proceeded efficiently under aerobic conditions by adding only a catalytic amount of BiI₃, which was non-hygroscopic and less toxic, and both selanyl groups of the diselenide were transferred to the desired products. Full article

(This article belongs to the Special Issue Organosulfur and Organoselenium Chemistry)

► Show Figures

Graphical abstract

4 pages, 167 KiB

Open AccessEditorial

Bioactive Properties and Chemical Composition of Wild Edible Species

by Spyridon A. Petropoulos

Molecules 2024, 29(13), 3226; https://doi.org/10.3390/molecules29133226 - 8 Jul 2024

Viewed by 731

Abstract

Wild edible species are usually collected from the wild, and they have been included in the human diet beyond the advent of agriculture, as confirmed by several ethnobotanical surveys [...] Full article

(This article belongs to the Special Issue Bioactive Properties and Chemical Composition of Wild Edible Species)

18 pages, 2777 KiB

Open AccessArticle

The Impact of Chemical Modifications on the Interferon-Inducing and Antiproliferative Activity of Short Double-Stranded Immunostimulating RNA

by Ali Bishani, Mariya I. Meschaninova, Marina A. Zenkova and Elena L. Chernolovskaya

Molecules 2024, 29(13), 3225; https://doi.org/10.3390/molecules29133225 - 7 Jul 2024

Viewed by 1714

Abstract

A short 19 bp dsRNA with 3′-trinucleotide overhangs acting as immunostimulating RNA (isRNA) demonstrated strong antiproliferative action against cancer cells, immunostimulatory activity through activation of cytokines and Type-I IFN secretion, as well as anti-tumor and anti-metastatic effects in vivo. The aim of this [...] Read more.

A short 19 bp dsRNA with 3′-trinucleotide overhangs acting as immunostimulating RNA (isRNA) demonstrated strong antiproliferative action against cancer cells, immunostimulatory activity through activation of cytokines and Type-I IFN secretion, as well as anti-tumor and anti-metastatic effects in vivo. The aim of this study was to determine the tolerance of chemical modifications (2′-F, 2′-OMe, PS, cholesterol, and amino acids) located at different positions within this isRNA to its ability to activate the innate immune system. The obtained duplexes were tested in vivo for their ability to activate the synthesis of interferon-α in mice, and in tumor cell cultures for their ability to inhibit their proliferation. The obtained data show that chemical modifications in the composition of isRNA have different effects on its individual functions, including interferon-inducing and antiproliferative effects. The effect of modifications depends not only on the type of modification but also on its location and the surrounding context of the modifications. This study made it possible to identify leader patterns of modifications that enhance the properties of isRNA: F2/F2 and F2_S/F2 for interferon-inducing activity, as well as F2_S5/F2_S5, F2-NH2/F2-NH2, and Ch-F2/Ch-F2 for antiproliferative action. These modifications can improve the pharmacokinetic and pharmacodynamic properties, as well as increase the specificity of isRNA action to obtain the desired effect. Full article

(This article belongs to the Special Issue The Current Landscape of Nucleic-Acid-Based Drugs)

► Show Figures

Figure 1

13 pages, 5106 KiB

Open AccessArticle

The Preparation of N, P-Doped NiSe Nanorod Electrode Materials on Nickel Foam Using the Microwave Method for High-Performance Supercapacitors

by Zhen Lu, Hongjie Kang, Qianwen Duan, Chao Lv, Rui Liu, Feng Feng and Haidong Zhao

Molecules 2024, 29(13), 3224; https://doi.org/10.3390/molecules29133224 - 7 Jul 2024

Cited by 1 | Viewed by 933

Abstract

Transition metal selenides have the leading position in the field of energy storage and conversion due to their high theoretical capacity, good electrical conductivity, and cycling stability. Nickel is widely used for the construction of positive electrodes in devices due to its good [...] Read more.

Transition metal selenides have the leading position in the field of energy storage and conversion due to their high theoretical capacity, good electrical conductivity, and cycling stability. Nickel is widely used for the construction of positive electrodes in devices due to its good conductivity, variable valence state, and ideal redox activity. NiSe materials have high internal resistance and are prone to volume change during charging and discharging, thus affecting the practical application of this electrode material, and the reported NiSe materials have not achieved a more desirable capacity value. Therefore, in this study, N, P-NiSe nanoelectrode materials were prepared using nickel foam as the nickel source and hexachlorocyclotriphonitrile as the nitrogen and phosphorus dopant using an efficient, energy-saving, and simple microwave method. It was also characterised by XRD and XPS to confirm the successful preparation of N, P-NiSe materials. In addition, the material yielded a high capacitance value (3184 F g⁻¹) and good cycling stability (72% of the initial capacitance value was retained after 4000 cycles) in electrochemical tests. To demonstrate its excellent suitability for practical applications, an asymmetric supercapacitor was assembled using N, P-NiSe as the anode and activated carbon as the cathode. At an operating voltage of 1.6 V, the device achieved an energy density of 289.06 Wh kg⁻¹ and a power density of 799.26 W kg⁻¹ and retained 80% of its initial capacity after 20,000 cycles. Full article

(This article belongs to the Special Issue Advanced Nanomaterials for Energy Storage Devices)

► Show Figures

Figure 1

19 pages, 4629 KiB

Open AccessArticle

Indigo Carmine Binding to Cu(II) in Aqueous Solution and Solid State: Full Structural Characterization Using NMR, FTIR and UV/Vis Spectroscopies and DFT Calculations

by Sofia Braz, Licínia L. G. Justino, M. Luísa Ramos and Rui Fausto

Molecules 2024, 29(13), 3223; https://doi.org/10.3390/molecules29133223 - 7 Jul 2024

Viewed by 1100

Abstract

The food industry uses indigo carmine (IC) extensively as a blue colorant to make processed food for young children and the general population more attractive. Given that IC can act as a ligand, this raises concerns about its interactions with essential metal ions [...] Read more.

The food industry uses indigo carmine (IC) extensively as a blue colorant to make processed food for young children and the general population more attractive. Given that IC can act as a ligand, this raises concerns about its interactions with essential metal ions in the human body. In view of this interest, in the present investigation, the copper(II)/indigo carmine system was thoroughly investigated in aqueous solution and in the solid state, and the detailed structural characterization of the complexes formed between copper(II) and the ligand was performed using spectroscopic methods, complemented with DFT and TD-DFT calculations. NMR and UV/Vis absorption spectroscopy studies of the ligand in the presence of copper(II) show changes that clearly reveal strong complexation. The results point to the formation of complexes of 1:1, 1:2 and 2:1 Cu(II)/IC stoichiometry in aqueous solution, favored in the pH range 6–10 and stable over time. DFT calculations indicate that the coordination of the ligand to the metal occurs through the adjacent carbonyl and amine groups and that the 1:1 and the 2:1 complexes have distorted tetrahedral metal centers, while the 1:2 structure is five-coordinate with a square pyramidal geometry. FTIR results, together with EDS data and DFT calculations, established that the complex obtained in the solid state likely consists of a polymeric arrangement involving repetition of the 1:2 complex unit. These results are relevant in the context of the study of the toxicity of IC and provide crucial data for future studies of its physiological effects. Although the general population does not normally exceed the maximum recommended daily intake, young children are highly exposed to products containing IC and can easily exceed the recommended dose. It is, therefore, extremely important to understand the interactions between the dye and the various metal ions present in the human body, copper(II) being one of the most relevant due to its essential nature and, as shown in this article, the high stability of the complexes it forms with IC at physiological pH. Full article

(This article belongs to the Section Inorganic Chemistry)

► Show Figures

Graphical abstract

23 pages, 1801 KiB

Open AccessArticle

Probiotic-Enriched Ice Cream with Fermented White Kidney Bean Homogenate: Survival, Antioxidant Activity, and Potential for Future Health Benefits

by Małgorzata Ziarno, Patrycja Cichońska, Ewa Kowalska and Dorota Zaręba

Molecules 2024, 29(13), 3222; https://doi.org/10.3390/molecules29133222 - 7 Jul 2024

Viewed by 1287

Abstract

This study investigated a novel probiotic-enriched ice cream containing fermented white kidney bean homogenate to explore its potential health benefits in the future. We assessed the viability of various probiotic strains during ice cream production and storage, focusing on their potential to reach [...] Read more.

This study investigated a novel probiotic-enriched ice cream containing fermented white kidney bean homogenate to explore its potential health benefits in the future. We assessed the viability of various probiotic strains during ice cream production and storage, focusing on their potential to reach the gut, and evaluated overall antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and total polyphenol content (TPC) assays. The incorporation of fermented white bean homogenate significantly increased antioxidant capacity compared to the control group. Notably, strains such as Lacticaseibacillus rhamnosus GG and Lactiplantibacillus plantarum 299v demonstrated the most pronounced effects on antioxidant activity, suggesting potential synergistic benefits between probiotics and bioactive compounds in fermented white beans. Although all probiotic strains experienced decreased viability during storage, certain strains, particularly L. plantarum 299v and Lacticaseibacillus casei DN-114001, showed promising survival rates even after 6 months. These results suggest the potential for developing probiotic ice cream containing viable bacteria capable of reaching the gut and contributing to a healthy gut microbiota. Overall, this study highlights the potential of probiotic-enriched ice cream with fermented white kidney bean homogenate to combine the established benefits of probiotics for gut health with the enjoyment of consuming ice cream. Full article

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

► Show Figures

Figure 1

14 pages, 2295 KiB

Open AccessArticle

The Role of Ovalbumin in Manganese Homeostasis during Chick Embryogenesis: An EPR Spectroscopic Study

by Ana Vesković, Aleksandra M. Bondžić and Ana Popović Bijelić

Molecules 2024, 29(13), 3221; https://doi.org/10.3390/molecules29133221 - 7 Jul 2024

Viewed by 1009

Abstract

Ovalbumin (OVA), a protein vital for chick embryo nutrition, hydration, and antimicrobial protection, together with other egg-white proteins, migrates to the amniotic fluid and is orally absorbed by the embryo during embryogenesis. Recently, it has been shown that for optimal eggshell quality, the [...] Read more.

Ovalbumin (OVA), a protein vital for chick embryo nutrition, hydration, and antimicrobial protection, together with other egg-white proteins, migrates to the amniotic fluid and is orally absorbed by the embryo during embryogenesis. Recently, it has been shown that for optimal eggshell quality, the hen diet can be supplemented with manganese. Although essential for embryonic development, manganese in excess causes neurotoxicity. This study investigates whether OVA may be involved in the regulation of manganese levels. The binding of Mn(II) to OVA was investigated using electron paramagnetic resonance (EPR) spectroscopy. The results show that OVA binds a maximum of two Mn(II) ions, one with slightly weaker affinity, even in a 10-fold excess, suggesting it may have a protective role from Mn(II) overload. It seems that the binding of Mn(II), or the presence of excess Mn(II), does not affect OVA’s tertiary structure, as evidenced from fluorescence and UV/vis measurements. Comparative analysis with bovine and human serum albumins revealed that they exhibit higher affinities for Mn(II) than OVA, most likely due to their essentially different physiological roles. These findings suggest that OVA does not play a role in the transport and storage of manganese; however, it may be involved in embryo protection from manganese-induced toxicity. Full article

(This article belongs to the Special Issue Molecular Spectroscopy in Applied Chemistry)

► Show Figures

Graphical abstract

14 pages, 4414 KiB

Open AccessArticle

Reactivity of Resorcinol on Pt(511) Single-Crystal Surface and Its Effect on the Kinetics of Underpotentially Deposited Hydrogen and Hydrogen Evolution Reaction in 0.1 M NaOH Electrolyte

by Bogusław Pierożyński, Mateusz Kuczyński, Tomasz Mikołajczyk and Piotr Sołowiej

Molecules 2024, 29(13), 3220; https://doi.org/10.3390/molecules29133220 - 7 Jul 2024

Viewed by 790

Abstract

This article presents cyclic voltammetry, Tafel polarization, and ac. impedance spectroscopy examinations of resorcinol (RC) ion reactivity on Pt(511) single-crystal plane and the effect of surface-electrosorbed RC ions on the kinetics of UPD H (underpotentially deposited hydrogen) and HER (hydrogen evolution reaction) [...] Read more.

This article presents cyclic voltammetry, Tafel polarization, and ac. impedance spectroscopy examinations of resorcinol (RC) ion reactivity on Pt(511) single-crystal plane and the effect of surface-electrosorbed RC ions on the kinetics of UPD H (underpotentially deposited hydrogen) and HER (hydrogen evolution reaction) processes in 0.1 M NaOH solution. Obtained data delivered a proof for the RC ion surface adsorption and its later electroreduction over the potential range characteristic for the UPD H. A favourable role of platinum-adsorbed resorcinol anions on the kinetics of the UPD H and HER processes is also discussed. The above was explained via the recorded capacitance and charge-transfer resistance parameters (the presence of resorcinol at 1.5 × 10⁻³ M in 0.1 M NaOH caused significant reduction in the resistance parameter values by 3.9 and 2.6 times, correspondingly, for the UPD of H at 50 mV and the HER process, examined at −50 mV vs. RHE) along with the charge transients, produced by injecting small amounts of RC-based 0.1 M NaOH solution to initially RC-free base electrolyte on the Pt(511) electrode plane (a large cathodic charge-transient density of −90 µC cm⁻² was recorded at the electrode potential of 50 mV). Full article

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

► Show Figures

Figure 1

18 pages, 7285 KiB

Open AccessArticle

A Strategy for Anode Recovery and Upgrading by In Situ Growth of Iron-Based Oxides on Microwave-Puffed Graphite

by Wenxin Chen, Jing Sun, Pingshan Jia, Wenlong Wang, Zhanlong Song, Ziliang Wang, Xiqiang Zhao and Yanpeng Mao

Molecules 2024, 29(13), 3219; https://doi.org/10.3390/molecules29133219 - 7 Jul 2024

Viewed by 907

Abstract

Faced with the increasing volume of retired lithium-ion batteries (LIBs), recycling and reusing the spent graphite (SG) is of great significance for resource sustainability. Here, a facile method for transforming the SG into a carbon framework as well as loading Fe₂O [...] Read more.

Faced with the increasing volume of retired lithium-ion batteries (LIBs), recycling and reusing the spent graphite (SG) is of great significance for resource sustainability. Here, a facile method for transforming the SG into a carbon framework as well as loading Fe₂O₃ to form a composite anode with a sandwich structure is proposed. Taking advantage of the fact that the layer spacing of the spent graphite naturally expands, impurities and intercalants are eliminated through microwave thermal shock to produce microwave-puffed graphite (MPG) with a distinct three-dimensional structure. Based on the mechanism of microwave-induced gasification intercalation, a Fe₂O₃-MPG intercalation compound (Fe₂O₃-MPGIC) anode material was constructed by introducing iron precursors between the framework layers and subsequently converting them into Fe₂O₃ through annealing. The Fe₂O₃-MPGIC anode exhibits a high reversible capacity of 1000.6 mAh g⁻¹ at 200 mA g⁻¹ after 100 cycles and a good cycling stability of 504.4 mAh g⁻¹ at 2000 mA g⁻¹ after 500 cycles. This work can provide a reference for the feasible recycling of SG and development of high-performance anode materials for LIBs. Full article

(This article belongs to the Special Issue Carbon-Based Electrochemical Materials for Energy Storage)

► Show Figures

Graphical abstract

12 pages, 2335 KiB

Open AccessArticle

[Fe(µ₂-OH)₆]³⁻ Linked Fe₃O Triads: Mössbauer Evidence for Trigonal µ₃-O²⁻ or µ₃-OH⁻ Groups in Bridged versus Unbridged Complexes

by D. Nirosha T. De Silva, Tyson N. Dais, Geoffrey B. Jameson, Casey G. Davies, Guy N. L. Jameson and Paul G. Plieger

Molecules 2024, 29(13), 3218; https://doi.org/10.3390/molecules29133218 - 7 Jul 2024

Viewed by 1133

Abstract

The syntheses, coordination chemistry, and Mössbauer spectroscopy of hepta-iron(III) complexes using derivatised salicylaldoxime ligands from two categories; namely, ‘single-headed’ (H₂L) and ‘double-headed’ (H₄L) salicylaldoximes are described. All compounds presented here share a [Fe₃-µ₃-O] [...] Read more.

The syntheses, coordination chemistry, and Mössbauer spectroscopy of hepta-iron(III) complexes using derivatised salicylaldoxime ligands from two categories; namely, ‘single-headed’ (H₂L) and ‘double-headed’ (H₄L) salicylaldoximes are described. All compounds presented here share a [Fe₃-µ₃-O] core in which the iron(III) ions are µ₃-hydroxo-bridged in the complex C1 and µ₃-oxo-bridged in C2 and C3. Each compound consists of 2 × [Fe₃-µ₃-O] triads that are linked via a central [Fe(µ₂-OH)₆]³⁻ ion. In addition to the charge balance and microanalytical evidence, Mössbauer measurements support the fact that the triads in C1 are µ₃-OH bridged and are µ₃-O bridged in C2 and C3. Full article

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

► Show Figures

Graphical abstract

14 pages, 3381 KiB

Open AccessArticle

Preparation and Screening of SRB Gel Particles Used for Deep Purification of Acid Mine Drainage

by Chunpeng Leng, Xi He, Yukuo Liu, Lifeng Shi, Fuping Li, Hao Wang, Cong Zhao, Siyu Yi and Lei Yu

Molecules 2024, 29(13), 3217; https://doi.org/10.3390/molecules29133217 - 6 Jul 2024

Cited by 1 | Viewed by 1229

Abstract

The progressive decline of the coal industry necessitates the development of effective treatment solutions for acid mine drainage (AMD), which is characterized by high acidity and elevated concentrations of heavy metals. This study proposes an innovative approach leveraging sulfate-reducing bacteria (SRB) acclimated to [...] Read more.

The progressive decline of the coal industry necessitates the development of effective treatment solutions for acid mine drainage (AMD), which is characterized by high acidity and elevated concentrations of heavy metals. This study proposes an innovative approach leveraging sulfate-reducing bacteria (SRB) acclimated to contaminated anaerobic environments. The research focused on elucidating the physiological characteristics and optimal growth conditions of SRB, particularly in relation to the pH level and temperature. The experimental findings reveal that the SRB exhibited a sulfate removal rate of 88.86% at an optimal temperature of 30 °C. Additionally, SRB gel particles were formulated using sodium alginate (SA) and carboxymethyl cellulose (CMC), and their performance was assessed under specific conditions (pH = 6, C/S = 1.5, T = 30 °C, CMC = 4.5%, BSNa = 0.4 mol/L, and cross-linking time = 9 h). Under these conditions, the SRB gel particles demonstrated an enhanced sulfate removal efficiency of 91.6%. Thermal analysis via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) provided further insights into the stability and properties of the SRB gel spheres. The findings underscore the potential of SRB-based bioremediation as a sustainable and efficient method for AMD treatment, offering a novel and environmentally friendly solution to mitigating the adverse effects of environmental contamination. Full article

(This article belongs to the Topic Sustainable Water Purification Technologies for Multiple Applications)

► Show Figures

Graphical abstract

24 pages, 5247 KiB

Open AccessReview

Recent Advances on the Functionalities of Polyoxometalate-Based Ionic Liquids

by Hongxue Wang and Bao Li

Molecules 2024, 29(13), 3216; https://doi.org/10.3390/molecules29133216 - 6 Jul 2024

Cited by 1 | Viewed by 1208

Abstract

Polyoxometalate (POM)-based ionic liquids (POM-ILs) are gaining increasing attention due to their diverse structures and functionalities. POMs in POM-ILs not only act as essential structural building blocks but also play a crucial role in their functional performance. With the incorporation of POMs, POM-ILs [...] Read more.

Polyoxometalate (POM)-based ionic liquids (POM-ILs) are gaining increasing attention due to their diverse structures and functionalities. POMs in POM-ILs not only act as essential structural building blocks but also play a crucial role in their functional performance. With the incorporation of POMs, POM-ILs find applications in various fields such as chemical catalysis, energy science, materials science, sensors, and more. The abundant availability of POMs and other building blocks in POM-ILs, along with their versatile combination possibilities, present promising opportunities for the future. Rather than focusing solely on discovering new structures of POM-ILs, current developments in this field emphasize exploring their functions, leading to the emergence of numerous new applications. Summarizing these advancements aids in understanding the latest trends and facilitates rapid evolution. This review examines the recent five years’ worth of results to analyze the new functions of POM-ILs, categorizing them based on their unique characteristics. Full article

(This article belongs to the Section Inorganic Chemistry)

► Show Figures

Graphical abstract

21 pages, 5417 KiB

Open AccessArticle

Ruthenium p-Cymene Complexes Incorporating Substituted Pyridine–Quinoline-Based Ligands: Synthesis, Characterization, and Cytotoxic Properties

by Afroditi Kokkosi, Elpida Garofallidou, Nikolaos Zacharopoulos, Nikolaos Tsoureas, Konstantina Diamanti, Nikolaos S. Thomaidis, Antigoni Cheilari, Christina Machalia, Evangelia Emmanouilidou and Athanassios I. Philippopoulos

Molecules 2024, 29(13), 3215; https://doi.org/10.3390/molecules29133215 - 6 Jul 2024

Cited by 1 | Viewed by 1564

Abstract

Organometallic complexes of the formula [Ru(N^N)(p-cymene)Cl][X] (N^N = bidentate polypyridyl ligands, p-cymene = 1-methyl-4-(1-methylethyl)-benzene, X = counter anion), are currently studied as possible candidates for the potential treatment of cancer. Searching for new organometallic compounds with good to moderate cytotoxic [...] Read more.

Organometallic complexes of the formula [Ru(N^N)(p-cymene)Cl][X] (N^N = bidentate polypyridyl ligands, p-cymene = 1-methyl-4-(1-methylethyl)-benzene, X = counter anion), are currently studied as possible candidates for the potential treatment of cancer. Searching for new organometallic compounds with good to moderate cytotoxic activities, a series of mononuclear water-soluble ruthenium(II)–arene complexes incorporating substituted pyridine–quinoline ligands, with pending -CH₂OH, -CO₂H and -CO₂Me groups in the 4-position of quinoline ring, were synthesized, for the first time, to study their possible effect to modulate the activity of the ruthenium p-cymene complexes. These include the [Ru(η⁶-p-cymene)(pqhyme)Cl][X] (X = Cl⁻ (1-Cl), PF₆⁻ (1-PF₆), pqhyme = 4-hydroxymethyl-2-(pyridin-2-yl)quinoline), [Ru(η⁶-p-cymene)(pqca)Cl][Cl] ((2-Cl), pqca = 4-carboxy-2-(pyridin-2-yl)quinoline), and [Ru(η⁶-p-cymene)(pqcame)Cl][X] (X = Cl⁻ (3-Cl), PF₆⁻ (3-PF₆), pqcame = 4-carboxymethyl-2-(pyridin-2-yl)quinoline) complexes, respectively. Identification of the complexes was based on multinuclear NMR and ATR-IR spectroscopic methods, elemental analysis, conductivity measurements, UV–Vis spectroscopic, and ESI-HRMS techniques. The solid-state structures of 1-PF₆ and 3-PF₆ have been elucidated by single-crystal X-ray diffraction revealing a three-legged piano stool geometry. This is the first time that the in vitro cytotoxic activities of these complexes are studied. These were conducted in HEK293T (human embryonic kidney cells) and HeLa cells (cervical cancer cells) via the MTT assay. The results show poor in vitro anticancer activities for the HeLa cancer cell lines and 3-Cl proved to be the most potent (IC₅₀ > 80 μΜ). In both cell lines, the cytotoxicity of the ligand precursor pqhyme is significantly higher than that of cisplatin. Full article

(This article belongs to the Special Issue Recent Advance in Transition Metal Complexes and Their Applications II)

► Show Figures

Graphical abstract

53 pages, 15874 KiB

Open AccessReview

How the Chemical Properties of Polysaccharides Make It Possible to Design Various Types of Organic–Inorganic Composites for Catalytic Applications

by Sandugash Akhmetova, Alima Zharmagambetova, Eldar Talgatov, Assemgul Auyezkhanova, Makpal Malgazhdarova, Murat Zhurinov, Arlan Abilmagzhanov, Aigul Jumekeyeva and Alima Kenzheyeva

Molecules 2024, 29(13), 3214; https://doi.org/10.3390/molecules29133214 - 6 Jul 2024

Viewed by 1013

Abstract

Recently, the use of plant-origin materials has become especially important due to the aggravation of environmental problems and the shortage and high cost of synthetic materials. One of the potential candidates among natural organic compounds is polysaccharides, characterized by a number of advantages [...] Read more.

Recently, the use of plant-origin materials has become especially important due to the aggravation of environmental problems and the shortage and high cost of synthetic materials. One of the potential candidates among natural organic compounds is polysaccharides, characterized by a number of advantages over synthetic polymers. In recent years, natural polysaccharides have been used to design composite catalysts for various organic syntheses. This review is devoted to the current state of application of polysaccharides (chitosan, starch, pectin, cellulose, and hydroxyethylcellulose) and composites based on their catalysis. The article is divided into four main sections based on the type of polysaccharide: (1) chitosan-based nanocomposites; (2) pectin-based nanocomposites; (3) cellulose (hydroxyethylcellulose)-based nanocomposites; and (4) starch-based nanocomposites. Each section describes and summarizes recent studies on the preparation and application of polysaccharide-containing composites in various chemical transformations. It is shown that by modifying polysaccharides, polymers with special properties can be obtained, thus expanding the range of biocomposites for catalytic applications. Full article

(This article belongs to the Special Issue Chitosan, Chitosan Derivatives, Polysaccharides and Their Applications—2nd Edition)

► Show Figures

Figure 1

16 pages, 6283 KiB

Open AccessArticle

Base-Free Oxidation of HMF to FDCA over Ru/Cu-Co-O·MgO under Aqueous Conditions

by Shuang Zhang, Guoning Chu, Sai Wang, Ji Ma and Chengqian Wang

Molecules 2024, 29(13), 3213; https://doi.org/10.3390/molecules29133213 - 6 Jul 2024

Viewed by 1105

Abstract

The copper–cobalt metal oxide composite magnesium oxide catalyst loaded with Ru has achieved the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to the bio-based polyester monomer 2,5-furandicarboxylic acid (FDCA) under base-free conditions. Several Ru/Cu-Co-O·MgO catalysts were prepared, with Cu-Co-O being a combination of CuO and [...] Read more.

The copper–cobalt metal oxide composite magnesium oxide catalyst loaded with Ru has achieved the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to the bio-based polyester monomer 2,5-furandicarboxylic acid (FDCA) under base-free conditions. Several Ru/Cu-Co-O·MgO catalysts were prepared, with Cu-Co-O being a combination of CuO and Co₃O₄. The catalyst’s activity was boosted by the synergistic interaction between copper and cobalt, as well as an optimal copper-to-cobalt molar ratio. Optimal catalytic activity was observed in the Ru₄/Cu1-Co1-O·MgO catalyst, loaded with 4 wt% Ru when copper-to-cobalt molar ratio of 1:1 and magnesium oxide compounding amount of 6 mmol were employed. The inclusion of MgO and the load of Ru not only expanded the specific surface area of the catalyst but also heightened its basicity. Additionally, the presence of loaded Ru improved the catalyst’s reducibility at low temperatures. In aqueous solution under oxygen pressure, the conversion rate of HMF achieved 100%, and the yield of FDCA was 86.1%. After five reaction cycles, examining the catalyst and solution revealed that Ru nanoparticles resisted leaching or oxidation, and MgO exhibited only slight dissolution. The green separation of the product was achieved using semi-preparative liquid chromatography, selectively collecting the FDCA-containing solution by exploiting variations in interactions between solutes and the stationary/mobile phases. The subsequent steps involved rotary evaporation and drying, resulting in FDCA powder with a purity exceeding 99%. Notably, this approach eliminated the need to introduce concentrated hydrochloric acid into the system for FDCA separation, providing a novel method for synthesising powdered FDCA. Full article

► Show Figures

Figure 1

Journal Menu

Journal Browser

Molecules, Volume 29, Issue 13 (July-1 2024) – 295 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI