Journal Description
Molecules
Molecules
is the leading international, peer-reviewed, open access journal of chemistry. Molecules is published semimonthly online by MDPI. The International Society of Nucleosides, Nucleotides & Nucleic Acids (IS3NA), the Spanish Society of Medicinal Chemistry (SEQT) and the International Society of Heterocyclic Chemistry (ISHC) are affiliated with Molecules and their members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), PubMed, MEDLINE, PMC, Reaxys, CaPlus / SciFinder, MarinLit, AGRIS, and other databases.
- Journal Rank: JCR - Q2 (Chemistry, Multidisciplinary) / CiteScore - Q1 (Chemistry (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 14.6 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Sections: published in 26 topical sections.
- Testimonials: See what our editors and authors say about Molecules.
- Companion journals for Molecules include: Foundations and Photochem.
Impact Factor:
4.6 (2022);
5-Year Impact Factor:
4.9 (2022)
Latest Articles
Rational Design of Magnetic Nanoparticles as T1–T2 Dual-Mode MRI Contrast Agents
Molecules 2024, 29(6), 1352; https://doi.org/10.3390/molecules29061352 (registering DOI) - 18 Mar 2024
Abstract
Magnetic nanoparticles (MNPs), either paramagnetic or superparamagnetic depending on their composition and size, have been thoroughly studied as magnetic resonance imaging (MRI) contrast agents using in vitro and in vivo biomedical preclinical studies, while some are clinically used. Their magnetic properties responsible in
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Magnetic nanoparticles (MNPs), either paramagnetic or superparamagnetic depending on their composition and size, have been thoroughly studied as magnetic resonance imaging (MRI) contrast agents using in vitro and in vivo biomedical preclinical studies, while some are clinically used. Their magnetic properties responsible in some cases for high magnetization values, together with large surface area-to-volume ratios and the possibility of surface functionalization, have been used in MRI-based diagnostic and theranostics applications. MNPs are usually used as positive (T1) or negative (T2) MRI contrast agents, causing brightening or darkening of selected regions in MRI images, respectively. This review focusses on recent developments and optimization of MNPs containing Gd, Mn, Fe and other lanthanide ions which may function as dual-mode T1–T2 MRI contrast agents (DMCAs). They induce positive or negative contrast in the same MRI scanner upon changing its operational mode between T1-weighted and T2-weighted pulse sequences. The type of contrast they induce depends critically on their r2/r1 relaxivity ratio, which for DMCAs should be in the 2–10 range of values. After briefly discussing the basic principles of paramagnetic relaxation in MNPs, in this review, the basic strategies for the rational design of DMCAs are presented and typical examples are discussed, including in vivo preclinical applications: (1) the use of NPs with a single type of contrast material, Gd- or Mn-based NPs or superparamagnetic NPs with appropriate size and magnetization to provide T2 and T1 contrast; and (2) inclusion of both types of T1 and T2 contrast materials in the same nanoplatform by changing their relative positions.
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(This article belongs to the Special Issue MRI Contrast Agents: Current Challenges and New Progresses)
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Green Approach to Enhance the Recovery of Polyphenols from Blackcurrant and Bilberry Leaves: Evaluation of Microwave-Assisted and Pressurized Liquid Extraction
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Ivona Elez Garofulić, Maja Repajić, Ena Cegledi, Erika Dobroslavić, Ana Dobrinčić, Zoran Zorić, Sandra Pedisić, Tatjana Franković, Martina Breški and Verica Dragović-Uzelac
Molecules 2024, 29(6), 1351; https://doi.org/10.3390/molecules29061351 (registering DOI) - 18 Mar 2024
Abstract
The aim of the present study was to evaluate microwave-assisted (MAE) and pressurized liquid extraction (PLE) for the recovery of polyphenols from blackcurrant and bilberry leaves and the preservation of their antioxidant activity. The extractions were carried out varying the solvent/solid (SS) ratio,
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The aim of the present study was to evaluate microwave-assisted (MAE) and pressurized liquid extraction (PLE) for the recovery of polyphenols from blackcurrant and bilberry leaves and the preservation of their antioxidant activity. The extractions were carried out varying the solvent/solid (SS) ratio, temperature and time. During MAE, increasing the SS ratio increased the polyphenol concentration in the extracts from blackcurrant and bilberry leaves, while increasing the temperature had a positive effect only on bilberry polyphenols. During PLE, only a temperature increase was a determining factor for the isolation of blackcurrant leave polyphenols. Based on polyphenol recovery, optimal extraction parameters were established resulting in a yield of 62.10 and 56.06 mg/g dw in the blackcurrant and bilberry MAE extracts and 78.90 and 70.55 mg/g dw in the PLE extracts. The optimized extracts were profiled by UPLC ESI MS2, and their antioxidant capacity was evaluated through FRAP, DPPH, ABTS and ORAC assays. The characterization of the extracts by UPLC ESI MS2 confirmed flavonols as the predominant compounds in both blackcurrant and bilberry leaves, while flavan-3-ols and procyanidins were the main compounds responsible for high antioxidant capacity as confirmed by the ABTS and ORAC assays. Due to the extract composition and antioxidant capacity, PLE proved to be a technique of choice for the production of blackcurrant and bilberry leave extracts with high potential for use as value-added ingredients in the food and nutraceutical industry.
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(This article belongs to the Special Issue New Insights into Bioactive Compounds from Natural Sources)
Open AccessArticle
Novel Nanocomposites for Luminescent Thermometry with Two Different Modalities
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Masfer Alkahtani, Yahya A. Alzahrani, Abdulaziz Alromaeh and Philip Hemmer
Molecules 2024, 29(6), 1350; https://doi.org/10.3390/molecules29061350 - 18 Mar 2024
Abstract
In this work, we successfully integrated fluorescent nanodiamonds (FNDs) and lanthanide ion-doped upconversion nanoparticles (UCNPs) in a nanocomposite structure for simultaneous optical temperature sensing. The effective integration of FND and UCNP shells was confirmed by employing high-resolution TEM imaging, X-ray diffraction, and dual-excitation
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In this work, we successfully integrated fluorescent nanodiamonds (FNDs) and lanthanide ion-doped upconversion nanoparticles (UCNPs) in a nanocomposite structure for simultaneous optical temperature sensing. The effective integration of FND and UCNP shells was confirmed by employing high-resolution TEM imaging, X-ray diffraction, and dual-excitation optical spectroscopy. Furthermore, the synthesized ND@UCNP nanocomposites were tested by making simultaneous optical temperature measurements, and the detected temperatures showed excellent agreement within their sensitivity limit. The simultaneous measurement of temperature using two different modalities having different sensing physics but with the same composite nanoparticles inside is expected to greatly improve the confidence of nanoscale temperature measurements. This should resolve some of the controversy surrounding nanoscale temperature measurements in biological applications.
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Open AccessArticle
Microwave-Assisted Grafting of Coal onto Nitrogen-Doped Carbon Dots with a High Quantum Yield and Enhanced Photoluminescence Properties
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Chong Shi and Xian-Yong Wei
Molecules 2024, 29(6), 1349; https://doi.org/10.3390/molecules29061349 - 18 Mar 2024
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The fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized via a facile one-pot solvothermal process using coal (Jin 15 Anthracite and Shaerhu lignite) as raw materials and dimethyl formamide (DMF) as the solvent, employing a microwave pyrolysis method. This approach demonstrates remarkable efficacy in
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The fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized via a facile one-pot solvothermal process using coal (Jin 15 Anthracite and Shaerhu lignite) as raw materials and dimethyl formamide (DMF) as the solvent, employing a microwave pyrolysis method. This approach demonstrates remarkable efficacy in the development of nitrogen-doped carbon dots (N-CDs) with a high quantum yield (QY). The N-CDs prepared have strong photoluminescence properties. Moreover, the obtained N-CDs emit blue PL and are easily dispersed in polymethyl methacrylate (PMMA), preserving the inherent advantages of N-CDs and the PMMA matrix. The JN-CDs exhibit a high quantum yield (QY) of 49.5% and a production yield of 25.7%, respectively. In contrast, the SN-CDs demonstrate a quantum yield of 40% and a production yield of 35.1%. It is worth noting that the production yield and quantum yield of coal-based carbon dots are inversely related indices. The lower metamorphic degree of subbituminous coal favors an enhanced product yield, while the higher metamorphic degree of anthracite promotes an improved quantum yield in the product, which may be attributed to the presence of amorphous carbon within it. Consequently, we propose and discuss potential mechanisms underlying N-CD formation.
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Open AccessArticle
The Removal of Arsenic and Its Inorganic Forms from Marine Algae—A Base for Inexpensive and Efficient Fertilizers
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Jarosław Ostrowski, Alicja Drozd, Rafał Olchowski, Agnieszka Chałabis-Mazurek, Andrzej Sienkiewicz, Agnieszka Kierys, Kinga Morlo and Ryszard Dobrowolski
Molecules 2024, 29(6), 1348; https://doi.org/10.3390/molecules29061348 - 18 Mar 2024
Abstract
Newly synthesized cerium oxide was successfully obtained by the hard templating route. The optimal As(III) and As(V) adsorption onto the studied adsorbent was reached for the initial pH of 4.0 and a contact time of 10 h. The highest static adsorption capacities for
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Newly synthesized cerium oxide was successfully obtained by the hard templating route. The optimal As(III) and As(V) adsorption onto the studied adsorbent was reached for the initial pH of 4.0 and a contact time of 10 h. The highest static adsorption capacities for As(III) and As(V) were 92 mg g−1 and 66 mg g−1, respectively. The pseudo-second-order model was well fitted to the As(III) and As(V) experimental kinetics data. The Langmuir model described the As(III) and As(V) adsorption isotherms on synthesized material. The adsorption mechanism of the studied ions onto the synthesized cerium oxide was complex and should be further investigated. The optimal solid–liquid ratio during the proposed aqueous extraction of inorganic As from the Fucus vesiculosus algae was 1:50. The optimal dosage of the synthesized cerium oxide (0.06 g L−1) was successfully applied for the first time for inorganic As removal from the aqueous algal extract.
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(This article belongs to the Special Issue Heavy Metals and Metalloids in Environmental, Food and Nutrients Samples)
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Open AccessArticle
Study of the Structure and Bioactivity of Polysaccharides from Different Parts of Stemona tuberosa Lour
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Xiang Qiu, Yanghui Ou, Shengjia Lu, Yibin Liang, Yali Zhang, Mengjie Li, Gang Li, Hongwei Ma, Yanting Wu, Zhaoyu He, Zhensheng Zhang, Hongliang Yao and Wen-Hua Chen
Molecules 2024, 29(6), 1347; https://doi.org/10.3390/molecules29061347 - 18 Mar 2024
Abstract
The polysaccharides from Stemona tuberosa Lour, a kind of plant used in Chinese herbal medicine, have various pharmacological activities, such as anti-inflammatory and antioxidant properties. However, the effects of the extraction methods and the activity of polysaccharides from different parts are still unknown.
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The polysaccharides from Stemona tuberosa Lour, a kind of plant used in Chinese herbal medicine, have various pharmacological activities, such as anti-inflammatory and antioxidant properties. However, the effects of the extraction methods and the activity of polysaccharides from different parts are still unknown. Therefore, this study aimed to evaluate the effects of different extraction methods on the yields, chemical compositions, and bioactivity of polysaccharides extracted from different parts of Stemona tuberosa Lour. Six polysaccharides were extracted from the leaves, roots, and stems of Stemona tuberosa Lour through the use of hot water (i.e., SPS-L1, SPS-R1, and SPS-S1) and an ultrasound-assisted method (i.e., SPS-L2, SPS-R2, and SPS-S2). The results showed that the physicochemical properties, structural properties, and biological activity of the polysaccharides varied with the extraction methods and parts. SPS-R1 and SPS-R2 had higher extraction yields and total sugar contents than those of the other SPSs (SPS-L1, SPS-L2, SPS-S1, and SPS-S2). SPS-L1 had favorable antioxidant activity and the ability to downregulate MUC5AC expression. An investigation of the anti-inflammatory properties showed that SPS-R1 and SPS-R2 had greater anti-inflammatory activities, while SPS-R2 demonstrated the strongest anti-inflammatory potential. The results of this study indicated that SPS-L1 and SPS-L2, which were extracted from non-medicinal parts, may serve as potent natural antioxidants, but further study is necessary to explore their potential applications in the treatment of diseases. The positive anti-inflammatory effects of SPS-R1 and SPS-R2 in the roots may be further exploited in drugs for the treatment of inflammation.
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(This article belongs to the Special Issue Polysaccharides and Their Biological Activities)
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Open AccessReview
Comprehensive Review on Chiral Stationary Phases in Single-Column Simultaneous Chiral–Achiral HPLC Separation Methods
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Lajos Attila Papp, Zoltán István Szabó, Gabriel Hancu, Lénárd Farczádi and Eleonora Mircia
Molecules 2024, 29(6), 1346; https://doi.org/10.3390/molecules29061346 - 18 Mar 2024
Abstract
This comprehensive review explores the utilization of chiral stationary phases (CSPs) in the context of single-column simultaneous chiral–achiral high-performance liquid chromatography (HPLC) separation methods. While CSPs have traditionally been pivotal for enantioselective drug analysis, contemporary CSPs often exhibit notable chemoselective properties. Consequently, there
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This comprehensive review explores the utilization of chiral stationary phases (CSPs) in the context of single-column simultaneous chiral–achiral high-performance liquid chromatography (HPLC) separation methods. While CSPs have traditionally been pivotal for enantioselective drug analysis, contemporary CSPs often exhibit notable chemoselective properties. Consequently, there is a discernible trend towards the development of methodologies that enable simultaneous enantio- and chemoselective separations utilizing a single CSP-based chromatographic column. This review provides an exhaustive overview of reported HPLC methods in this domain, with a focus on four major CSP types: cyclodextrin-, glycopeptide antibiotic-, protein-, and polysaccharide-based CSPs. This article delves into the diverse applications of CSPs, encompassing various chromatographic modes such as normal phase (NP), reverse phase (RP), and polar organic (PO). This review critically discusses method development, emphasizing the additional chemoselective separation mechanisms of CSPs. It also explores possibilities for method optimization and development, concluding with future perspectives on this evolving field. Despite the inherent challenges in understanding the retention mechanisms involved in chemoselective separations, this review highlights promising trends and anticipates a growing number of simultaneous enantio- and chemoselective methods in pharmaceutical analyses, pharmacokinetic studies, and environmental sample determinations.
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(This article belongs to the Section Analytical Chemistry)
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Turn Waste Golden Tide into Treasure: Bio-Adsorbent Synthesis for CO2 Capture with K2FeO4 as Catalytic Oxidative Activator
by
Huijuan Ying, Chenglin Jia, Ganning Zeng and Ning Ai
Molecules 2024, 29(6), 1345; https://doi.org/10.3390/molecules29061345 - 18 Mar 2024
Abstract
Converting Sargassum horneri (SH)—a harmful marine stranding that can cause golden tide—to highly porous bio-adsorbent material (via one-step catalytic oxidative pyrolysis with K2FeO4) can be a strategically useful method for obtaining low-cost materials suitable for CO2 capture. In
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Converting Sargassum horneri (SH)—a harmful marine stranding that can cause golden tide—to highly porous bio-adsorbent material (via one-step catalytic oxidative pyrolysis with K2FeO4) can be a strategically useful method for obtaining low-cost materials suitable for CO2 capture. In this manuscript, the behavior of different mass ratios of K2FeO4/SH precursor acting on the surface physicochemical properties of carbon materials are reported. The results suggest that specific surface area and total pore volume first increased to the mass ratio of K2FeO4/carbon precursor, then decreased. Among the samples prepared, the highest specific surface area was obtained with a K2FeO4/SH precursor ratio of 1:4 (25%-ASHC), and the CO2 adsorption performance was significantly increased and faster compared with the original biochar. The fitted values of the three kinetic models showed that the double exponential model provided the best description of carbon adsorption, indicating both physical and chemical adsorption; 25%-ASHC also exhibited excellent cyclic stability. The improved CO2 adsorption performance observed after K2FeO4 activation is mainly due to the increase in material porosity, specific surface area, and the enrichment of nitrogen and oxygen functional groups.
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(This article belongs to the Special Issue Renewable Energy, Fuels and Chemicals from Biomass)
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DFT Studies of Dimethylaminophenyl-Substituted Phthalocyanine and Its Silver Complexes
by
Martin Breza
Molecules 2024, 29(6), 1344; https://doi.org/10.3390/molecules29061344 - 18 Mar 2024
Abstract
The dimethylaminophenyl-substituted silver phthalocyanine [dmaphPcAg] can be used as a UV-vis photoinitiator for in situ preparation of a silver/polymer nanocomposite. To verify early steps of the supposed mechanism of radical polymerization, we performed quantum chemical calculations of m[dmaphPcAg]q complexes with charges
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The dimethylaminophenyl-substituted silver phthalocyanine [dmaphPcAg] can be used as a UV-vis photoinitiator for in situ preparation of a silver/polymer nanocomposite. To verify early steps of the supposed mechanism of radical polymerization, we performed quantum chemical calculations of m[dmaphPcAg]q complexes with charges q = +1 to −2 in the two lowest spin states m, of a free ligand and its dehydrogenated/deprotonated products m[dmaphPcHn]q, n = 2 to 0, q = 0, −1 or −2, in the lowest spin states m. The calculated electronic structures and electron transitions of all the optimized structures in CHCl3 solutions are compared with experimental EPR and UV-vis spectra, respectively. The unstable 3[dmaphPcAg]+ species deduced only from previous EPR spin trap experiments was identified. In addition to 2[dmaphPcAg]0, our results suggest the coexistence of both reaction intermediates 1[dmaphPcAg]− and 3[dmaphPcAg]− in reaction solutions. Silver nanoparticle formation is a weak point of the supposed reaction mechanism from the energetic, stereochemistry, and electronic structure points of view.
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(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes)
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Chemical Composition Variation in Essential Oil and Their Correlation with Climate Factors in Chinese Prickly Ash Peels (Zanthoxylum armatum DC.) from Different Habitats
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Qianqian Qian, Zhihang Zhuo, Yaqin Peng and Danping Xu
Molecules 2024, 29(6), 1343; https://doi.org/10.3390/molecules29061343 - 18 Mar 2024
Abstract
Essential oils are secondary metabolites in plants with a variety of biological activities. The flavor and quality of Zanthoxylum armatum DC. are mainly determined by the essential oil components in the Chinese prickly ash peels. In this study, the correlation between climate change
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Essential oils are secondary metabolites in plants with a variety of biological activities. The flavor and quality of Zanthoxylum armatum DC. are mainly determined by the essential oil components in the Chinese prickly ash peels. In this study, the correlation between climate change in different regions and the content of essential oils of Z. armatum was investigated using gas chromatography–mass spectrometry (GC/MS) and multivariate statistical analysis. The Z1–24 refers to 24 batches of samples from different habitats. A total of 145 essential oils were detected in 24 batches of samples, with the highest number of terpene species and the highest content of alcohol. The relative odor activity (ROAV) values identified nine main flavor compounds affecting the odor of Z. armatum. Linalool, decanal, and d-limonene were the most critical main flavor compounds, giving Z. armatum a spicy, floral, oily, and fruity odor. The results of hierarchical cluster analysis (HCA) and principal component analysis (PCA) classified Z5 into a separate group, Z2 and Z7 were clustered into one group, and the rest of the samples were classified into another group. Correlation analysis and path analysis showed that temperature and precipitation were the main climatic factors affecting essential oils. Comparisons can be made with other plants in the genus Zanthoxylum to analyze differences in essential oil type and content. This study contributes to the identification of Z. armatum quality, promotes the accumulation of theories on the effects of climatic factors on essential oils, and enriches the site selection and breeding of Z. armatum under similar climatic conditions.
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(This article belongs to the Special Issue Detection of Volatile Compounds in Foods)
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Open AccessArticle
Controllable La Deficiency Engineering within Perovskite Oxides for Enhanced Overall Water Splitting
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Xiaohu Xu, Kaiwei Guo and Xinyue Yu
Molecules 2024, 29(6), 1342; https://doi.org/10.3390/molecules29061342 - 18 Mar 2024
Abstract
Recently, perovskite (ABO3) nanomaterials have been widely explored as a class of versatile electrocatalysts for oxygen evolution reactions (OER) due to their remarkable compositional flexibility and structural tunability, but their poor electrical conductivity hinders hydrogen evolution reaction (HER) activity and further
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Recently, perovskite (ABO3) nanomaterials have been widely explored as a class of versatile electrocatalysts for oxygen evolution reactions (OER) due to their remarkable compositional flexibility and structural tunability, but their poor electrical conductivity hinders hydrogen evolution reaction (HER) activity and further limits the large-scale application of perovskite oxide in overall water splitting (OWS). In this study, hollow-nanotube-structure LaxCo0.4Fe0.6O3−δ (x = 1.0, 0.9, and 0.8) perovskites with superior HER/OER activity were synthesized on nickel-iron alloy foam (denoted LaxCoFe/NFF) using hydrothermal with a subsequent calcination strategy. Among them, La0.9CoFe/NFF not only exhibited extraordinary HER electrocatalytic performance (160.5 mV@10 mA cm−2 and 241.0 mV@100 mA cm−2) and stability (20 h@10 mA cm−2), but also displayed significant OER electrocatalytic activity (234.7 mV@10 mA cm−2 and 296.1 mV@100 mA cm−2) and durability (20 h@10 mA cm−2), outperforming many recently reported HER/OER perovskite catalysts. The increase in oxygen vacancies caused by the introduction of La deficiency leads to the expansion of the lattice, which greatly accelerates the HER/OER process of La0.9CoFe/NFF. Additionally, the naturally porous skeleton can prevent catalysts from aggregating as well as delay the corrosion and dissolution of catalysts in the electrolyte under high applied potentials. Furthermore, the assembled two-electrode configuration, utilizing La0.9CoFe/NFF (cathode and anode) electrodes, only requires a low cell voltage of 1.573 V at 10 mA cm−2 for robust alkaline OWS, accompanied by remarkable durability over 20 h. This work provides inspiration for the design and preparation of high-performance and stable bifunctional perovskite electrocatalysts for OWS.
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(This article belongs to the Special Issue 2D Nanosheets and Their Nanohybrids)
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Open AccessFeature PaperArticle
Synthesis and Spectroscopic Characterization of Selected Water-Soluble Ligands Based on 1,10-Phenanthroline Core
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Jacek E. Nycz, Natalia Martsinovich, Jakub Wantulok, Tieqiao Chen, Maria Książek and Joachim Kusz
Molecules 2024, 29(6), 1341; https://doi.org/10.3390/molecules29061341 - 18 Mar 2024
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Water-soluble ligands based on a 1,10-phenanthroline core are relatively poorly studied compounds. Developing efficient and convenient syntheses of them would result in new interesting applications because of the importance of 1,10-phenanthrolines. In this manuscript, we describe novel and practical ways to introduce a
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Water-soluble ligands based on a 1,10-phenanthroline core are relatively poorly studied compounds. Developing efficient and convenient syntheses of them would result in new interesting applications because of the importance of 1,10-phenanthrolines. In this manuscript, we describe novel and practical ways to introduce a carboxyl and, for the first time, a phenol and dithiocarboxyl group under mild reaction conditions. This strategy enables highly efficient and practical synthesis of suitable organosulfur compounds with high added value, high chemoselectivity, and a broad substrate range. We present the selective conversion of a hydroxydialdehyde in the form of 10-hydroxybenzo[h]quinoline-7,9-dicarbaldehyde into its derivative, unique hydroxydicarboxylic acid, by an oxidation procedure, giving 10-hydroxybenzo[h]quinoline-7,9-dicarboxylic acid. A similar procedure resulted in the formation of 9-methyl-1,10-phenanthroline-2-carboxylic acid by oxidation of commercially available neocuproine. An alternative method of obtaining 1,10-phenanthroline derivatives possessing carboxylic acid group can be based on the hydrolysis of ester or nitrile groups; however, this synthesis leads to unexpected products. Moreover, we apply Perkin condensation to synthesize a vinyl (or styryl) analog of 1,10-phenanthroline derivatives with phenol function. This reaction also demonstrates a new, simple, and efficient strategy for converting methyl derivatives of 1,10-phenanthroline. We anticipate that the new way of converting methyl will find wide application in chemical synthesis.
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Open AccessArticle
Effects of Ti3C2Tx MXene Addition to a Co Complex/Ionic Liquid-Based Electrolyte on the Photovoltaic Performance of Solar Cells
by
Ju Hee Gu, Dongho Park, Kyung-Hye Jung, Byung Chul Lee and Yoon Soo Han
Molecules 2024, 29(6), 1340; https://doi.org/10.3390/molecules29061340 - 18 Mar 2024
Abstract
Redox mediators comprising I−, Co3+, and Ti3C2Tx MXene were applied to dye-sensitized solar cells (DSCs). In the as-prepared DSCs (I-DSCs), wherein hole conduction occurred via the redox reaction of I−/I3− ions,
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Redox mediators comprising I−, Co3+, and Ti3C2Tx MXene were applied to dye-sensitized solar cells (DSCs). In the as-prepared DSCs (I-DSCs), wherein hole conduction occurred via the redox reaction of I−/I3− ions, the power conversion efficiency (PCE) was not altered by the addition of Ti3C2Tx MXene. The I-DSCs were exposed to light to produce Co2+/Co3+-based cells (Co-DSCs), wherein the holes were transferred via the redox reaction of Co2+/Co3+ ions. A PCE of 9.01% was achieved in a Co-DSC with Ti3C2Tx MXene (Ti3C2Tx-Co-DSC), which indicated an improvement from the PCE of a bare Co-DSC without Ti3C2Tx MXene (7.27%). It was also found that the presence of Ti3C2Tx MXene in the redox mediator increased the hole collection, dye regeneration, and electron injection efficiencies of the Ti3C2Tx-Co-DSC, leading to an improvement in both the short-circuit current and the PCE when compared with those of the bare Co-DSC without MXene.
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(This article belongs to the Special Issue Feature Papers in Photochemistry and Photocatalysis)
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Open AccessArticle
Quantification of Trimethylamine-N-Oxide and Trimethylamine in Fish Oils for Human Consumption
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Dominik Dörfel, Sascha Rohn and Eckard Jantzen
Molecules 2024, 29(6), 1339; https://doi.org/10.3390/molecules29061339 - 17 Mar 2024
Abstract
Supplementing fish oil is one of the strategies to reduce the risk of cardiovascular disease, the leading cause of death around the world. Contradictorily, fish oil may also contain trimethylamine-N-oxide, a recently emerged risk factor for cardiovascular disease, as well as
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Supplementing fish oil is one of the strategies to reduce the risk of cardiovascular disease, the leading cause of death around the world. Contradictorily, fish oil may also contain trimethylamine-N-oxide, a recently emerged risk factor for cardiovascular disease, as well as one of its precursors, trimethylamine. A method suitable for routine quantification of trimethylamine-N-oxide and trimethylamine in fish oil with a quick and easy liquid extraction without derivatization has been developed. Liquid chromatography with tandem mass spectrometry detection was employed along with a zwitterionic hydrophilic interaction liquid chromatography column and a gradient elution with eluents containing 50 mmol/L of ammonium formate. An internal standard (triethylamine) was used for quantification by mass spectrometry with an external calibration. The assay proved high linearity in the ranges of 10 to 100 ng/mL and 100 to 1000 ng/mL for trimethylamine-N-oxide and trimethylamine, respectively. The lowest limit of quantification was determined to be 100 µg/kg for trimethylamine and 10 µg/kg for trimethylamine-N-oxide, with the limit of detection at 5 µg/kg and 0.25 µg/kg, respectively. Accuracy ranged from 106–119%. Precision was below 7% the relative standard deviation for both analytes. The method was successfully applied for the determination of trimethylamine-N-oxide and trimethylamine contents in nine commercially available liquid fish oils and three commercially available fish oil capsules, showing that trimethylamine and trimethylamine-N-oxide are not present in highly refined fish oils.
Full article
(This article belongs to the Special Issue Bioactive Compounds from Functional Foods, 2nd Edition)
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Open AccessArticle
Molecular Insights into the Enhanced Activity and/or Thermostability of PET Hydrolase by D186 Mutations
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Zhi Qu, Lin Zhang and Yan Sun
Molecules 2024, 29(6), 1338; https://doi.org/10.3390/molecules29061338 - 17 Mar 2024
Abstract
PETase exhibits a high degradation activity for polyethylene terephthalate (PET) plastic under moderate temperatures. However, the effect of non-active site residues in the second shell of PETase on the catalytic performance remains unclear. Herein, we proposed a crystal structure- and sequence-based strategy to
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PETase exhibits a high degradation activity for polyethylene terephthalate (PET) plastic under moderate temperatures. However, the effect of non-active site residues in the second shell of PETase on the catalytic performance remains unclear. Herein, we proposed a crystal structure- and sequence-based strategy to identify the key non-active site residue. D186 in the second shell of PETase was found to be capable of modulating the enzyme activity and stability. The most active PETaseD186N improved both the activity and thermostability with an increase in Tm by 8.89 °C. The PET degradation product concentrations were 1.86 and 3.69 times higher than those obtained with PETaseWT at 30 and 40 °C, respectively. The most stable PETaseD186V showed an increase in Tm of 12.91 °C over PETaseWT. Molecular dynamics (MD) simulations revealed that the D186 mutations could elevate the substrate binding free energy and change substrate binding mode, and/or rigidify the flexible Loop 10, and lock Loop 10 and Helix 6 by hydrogen bonding, leading to the enhanced activity and/or thermostability of PETase variants. This work unraveled the contribution of the key second-shell residue in PETase in influencing the enzyme activity and stability, which would benefit in the rational design of efficient and thermostable PETase.
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(This article belongs to the Special Issue Feature Papers in Chemical Biology—Edition of 2022-2023)
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Open AccessArticle
Novel Meta-Diamide Compounds Containing Sulfide Derivatives Were Designed and Synthesized as Potential Pesticides
by
Jingwen Wu, Shuaihui Dang, Yan Zhang and Sha Zhou
Molecules 2024, 29(6), 1337; https://doi.org/10.3390/molecules29061337 - 17 Mar 2024
Abstract
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The meta-diamide (m-diamide) insecticide, Broflanilide, was characterized by its high efficiency, low toxicity and lack of cross-resistance with traditional GABA receptors. In accordance with the principles of drug molecular design, easily derivable sulfur with diverse bioactivities was introduced while leading with
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The meta-diamide (m-diamide) insecticide, Broflanilide, was characterized by its high efficiency, low toxicity and lack of cross-resistance with traditional GABA receptors. In accordance with the principles of drug molecular design, easily derivable sulfur with diverse bioactivities was introduced while leading with the parent Broflanilide. Twelve novel m-diamide target compounds containing sulfide derivatives were synthesized through exploration guided by the literature. Their structures were confirmed by melting points, 1H NMR, 13C NMR and HRMS. Insecticidal activity assessments revealed that most target compounds A–D exhibited 100% lethality against Plutella xylostella (P. xylostella) and Aphis craccivora Koch (A. craccivora) at 500 mg·L−1. Notably, for P. xylostella, compounds C-2, C-3, C-4 and D-2 demonstrated 60.00–100.00% insecticidal activity even at a concentration as low as 0.625 mg·L−1. As determined by structure–activity relationship (SAR) analysis, compounds with R1 = CH3 and R2 = Br (B-1, C-2 and D-2) and sulfoxide compound C-3 contained 100.00% lethality against A. craccivora at 500 mg·L−1, surpassing the lethality when leading with the parent Broflanilide in terms of efficacy. Consequently, it can be inferred that the sulfoxide compound (C-3) requires further investigation as a potential active molecule for new insecticides. These explorations provide valuable references for future research on the synthesis and insecticidal activities of sulfide-containing m-diamide compounds.
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Open AccessReview
Mass-Spectrometry-Based Research of Cosmetic Ingredients
by
Alina Florina Serb, Marius Georgescu, Robert Onulov, Cristina Ramona Novaconi, Eugen Sisu, Alexandru Bolocan and Raluca Elena Sandu
Molecules 2024, 29(6), 1336; https://doi.org/10.3390/molecules29061336 - 17 Mar 2024
Abstract
Cosmetic products are chemical substances or mixtures used on the skin, hair, nails, teeth, and the mucous membranes of the oral cavity, whose use is intended to clean, protect, correct body odor, perfume, keep in good condition, or change appearance. The analysis of
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Cosmetic products are chemical substances or mixtures used on the skin, hair, nails, teeth, and the mucous membranes of the oral cavity, whose use is intended to clean, protect, correct body odor, perfume, keep in good condition, or change appearance. The analysis of cosmetic ingredients is often challenging because of their huge complexity and their adulteration. Among various analytical tools, mass spectrometry (MS) has been largely used for compound detection, ingredient screening, quality control, detection of product authenticity, and health risk evaluation. This work is focused on the MS applications in detecting and quantification of some common cosmetic ingredients, i.e., preservatives, dyes, heavy metals, allergens, and bioconjugates in various matrices (leave-on or rinse-off cosmetic products). As a global view, MS-based analysis of bioconjugates is a narrow field, and LC- and GC/GC×GC-MS are widely used for the investigation of preservatives, dyes, and fragrances, while inductively coupled plasma (ICP)-MS is ideal for comprehensive analysis of heavy metals. Ambient ionization approaches and advanced separation methods (i.e., convergence chromatography (UPC2)) coupled to MS have been proven to be an excellent choice for the analysis of scented allergens. At the same time, the current paper explores the challenges of MS-based analysis for cosmetic safety studies.
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(This article belongs to the Special Issue Applied Chemistry in Europe 2024)
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Open AccessArticle
Multifaceted Characterization for the Hepatic Clearance of Graphene Oxide and Size-Related Hepatic Toxicity
by
Zongyi Su, Wei Chen, Shanshan Liang, Hao Fang, Minglu Zhang, Meng Wang, Lingna Zheng, Bing Wang, Yi Bi and Weiyue Feng
Molecules 2024, 29(6), 1335; https://doi.org/10.3390/molecules29061335 - 17 Mar 2024
Abstract
Understanding the final fate of nanomaterials (NMs) in the liver is crucial for their safer application. As a representative two-dimensional (2D) soft nanomaterial, graphene oxide (GO) has shown to have high potential for applications in the biomedical field, including in biosensing, drug delivery,
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Understanding the final fate of nanomaterials (NMs) in the liver is crucial for their safer application. As a representative two-dimensional (2D) soft nanomaterial, graphene oxide (GO) has shown to have high potential for applications in the biomedical field, including in biosensing, drug delivery, tissue engineering, therapeutics, etc. GO has been shown to accumulate in the liver after entering the body, and thus, understanding the GO–liver interaction will facilitate the development of safer bio-applications. In this study, the hepatic clearance of two types of PEGylated GOs with different lateral sizes (s-GOs: ~70 nm and l-GOs: ~300 nm) was carefully investigated. We found that GO sheets across the hepatic sinusoidal endothelium, which then may be taken up by the hepatocytes via the Disse space. The hepatocytes may degrade GO into dot-like particles, which may be excreted via the hepatobiliary route. In combination with ICP-MS, LA-ICP-MS, and synchrotron radiation FTIR techniques, we found that more s-GO sheets in the liver were prone to be cleared via hepatobiliary excretion than l-GO sheets. A Raman imaging analysis of ID/IG ratios further indicated that both s-GO and l-GO generated more defects in the liver. The liver microsomes may contribute to GO biotransformation into O-containing functional groups, which plays an important role in GO degradation and excretion. In particular, more small-sized GO sheets in the liver were more likely to be cleared via hepatobiliary excretion than l-GO sheets, and a greater clearance of s-GO will mitigate their hepatotoxicity. These results provide a better understanding of the hepatic clearance of soft NMs, which is important in the safer-by-design of GO.
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(This article belongs to the Special Issue Bioactive Molecules Targeting Inflammation Processes in Related Diseases—2nd Edition)
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Open AccessArticle
Purification and Biochemical Characterization of Polyphenol Oxidase Extracted from Wheat Bran (Wan grano)
by
Kun Yu, Wei He, Xiaoli Ma, Qi Zhang, Chunxu Chen, Peiyan Li and Di Wu
Molecules 2024, 29(6), 1334; https://doi.org/10.3390/molecules29061334 - 17 Mar 2024
Abstract
Currently, little is known about the characteristics of polyphenol oxidase from wheat bran, which is closely linked to the browning of wheat product. The wheat PPO was purified by ammonium sulfate precipitation, DEAE-Sepharose ion-exchange column, and Superdex G-75 chromatography column. Purified wheat PPO
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Currently, little is known about the characteristics of polyphenol oxidase from wheat bran, which is closely linked to the browning of wheat product. The wheat PPO was purified by ammonium sulfate precipitation, DEAE-Sepharose ion-exchange column, and Superdex G-75 chromatography column. Purified wheat PPO activity was 11.05-fold higher, its specific activity was 1365.12 U/mg, and its yield was 8.46%. SDS-PAGE showed that the molecular weight of wheat PPO was approximately 21 kDa. Its optimal pH and temperature were 6.5 and 35 °C for catechol as substrate, respectively. Twelve phenolic substrates from wheat and green tea were used for analyzing the substrate specificity. Wheat PPO showed the highest affinity to catechol due to its maximum Vmax (517.55 U·mL−1·min−1) and low Km (6.36 mM) values. Docking analysis revealed strong affinities between catechol, gallic acid, EGCG, and EC with binding energies of −5.28 kcal/mol, −4.65 kcal/mol, −4.21 kcal/mol, and −5.62 kcal/mol, respectively, for PPO. Sodium sulfite, ascorbic acid, and sodium bisulfite dramatically inhibited wheat PPO activity. Cu2+ and Ca2+ at 10 mM were considered potent activators and inhibitors for wheat PPO, respectively. This report provides a theoretical basis for controlling the enzymatic browning of wheat products fortified with green tea.
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(This article belongs to the Special Issue Extraction and Analysis of Natural Product in Food)
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Open AccessArticle
The Importance of Substituent Position for Antibacterial Activity in the Group of Thiosemicarbazide Derivatives
by
Sara Janowska, Joanna Stefańska, Dmytro Khylyuk and Monika Wujec
Molecules 2024, 29(6), 1333; https://doi.org/10.3390/molecules29061333 - 17 Mar 2024
Abstract
The search for new antibacterial compounds is still a huge challenge for scientists. Each new chemotherapy drug is not 100% effective when introduced into treatment. Bacteria quickly become resistant to known structures. One promising group of new compounds is thiosemicarbazides. In the presented
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The search for new antibacterial compounds is still a huge challenge for scientists. Each new chemotherapy drug is not 100% effective when introduced into treatment. Bacteria quickly become resistant to known structures. One promising group of new compounds is thiosemicarbazides. In the presented work, we looked for the relationship between structure and antibacterial activity within the group of thiosemicarbazide derivatives. This is a continuation of our previous work. Here, we decided to check to what extent the position of the 3-methoxyphenyl substituent affects potency. We obtained new structures that differ in the positions of the substituent in the thiosemicarbazide skeleton. Based on the obtained results of the biological tests, it can be concluded that the substituent in position 1 of thiosemicarbazide derivatives significantly determines their activity. Generally, among the substituents used, trifluoromethylphenyl turned out to be the most promising. The MIC values for compounds with this substituent are 64 µg/mL towards Staphylococci sp. Using molecular docking, we tried to explain the mechanism behind the antibacterial activity of the tested compounds.
Full article
(This article belongs to the Section Medicinal Chemistry)
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