Molecules

14 pages, 2080 KiB

Open AccessArticle

Optimisation of a Microwave Synthesis of Silver Nanoparticles by a Quality by Design Approach to Improve SERS Analytical Performances

by Julie Horne, Pierre Beckers, Pierre-Yves Sacré, Charlotte De Bleye, Pierre Francotte, Nicolas Thelen, Philippe Hubert, Eric Ziemons and Cédric Hubert

Molecules 2024, 29(14), 3442; https://doi.org/10.3390/molecules29143442 - 22 Jul 2024

Cited by 1 | Viewed by 1314

Abstract

A major limitation preventing the use of surface-enhanced Raman scattering (SERS) in routine analyses is the signal variability due to the heterogeneity of metallic nanoparticles used as SERS substrates. This study aimed to robustly optimise a synthesis process of silver nanoparticles to improve [...] Read more.

A major limitation preventing the use of surface-enhanced Raman scattering (SERS) in routine analyses is the signal variability due to the heterogeneity of metallic nanoparticles used as SERS substrates. This study aimed to robustly optimise a synthesis process of silver nanoparticles to improve the measured SERS signal repeatability and the protocol synthesis repeatability. The process is inspired by a chemical reduction method associated with microwave irradiation to guarantee better controlled and uniform heating. The innovative Quality by Design strategy was implemented to optimise the different parameters of the process. A preliminary investigation design was firstly carried out to evaluate the influence of four parameters selected by means of an Ishikawa diagram. The critical quality attributes were to maximise the intensity of the SERS response and minimise its variance. The reaction time, temperature and stirring speed are critical process parameters. These were optimised using an I-optimal design. A robust operating zone covering the optimal reaction conditions (3.36 min–130 °C–600 rpm) associated with a probability of success was modelled. Validation of this point confirmed the prediction with intra- and inter-batch variabilities of less than 15%. In conclusion, this study successfully optimised silver nanoparticles by a rapid, low cost and simple technique enhancing the quantitative perspectives of SERS. Full article

(This article belongs to the Section Green Chemistry)

► Show Figures

Graphical abstract

22 pages, 2048 KiB

Open AccessArticle

Development and Optimization Method for Determination of the Strawberries’ Aroma Profile

by Iva Palac Bešlić, Martina Ivešić, Ivana Mandić Andačić, Danijela Bursać Kovačević, Irena Žuntar, Anica Bebek Markovinović, Fabijan Oštarić and Adela Krivohlavek

Molecules 2024, 29(14), 3441; https://doi.org/10.3390/molecules29143441 - 22 Jul 2024

Viewed by 816

Abstract

The strawberry (genus Fragaria) is a plant from the rose family (Rosaceae). As the fruits are likely to be picked mechanically, they are grown close to consumption centers. The aim of this work was to develop a suitable method for detecting as [...] Read more.

The strawberry (genus Fragaria) is a plant from the rose family (Rosaceae). As the fruits are likely to be picked mechanically, they are grown close to consumption centers. The aim of this work was to develop a suitable method for detecting as many molecules as possible in order to be able to distinguish between different strawberry cultivars and geographical origins in the future. Whole strawberries of the “Albion” cultivar, grown in the Jagodica Purgerica region of Zagreb, were used. Gas chromatography-mass spectrometry (GC-MS) in SCAN mode was used to analyze the aroma profile and to determine the proportion of individual components. The samples were prepared and analyzed using the solid-phase microextraction method (SPME). The impact of SPME fiber selection and GC column type was investigated, as well as sample weight, ionic strength, agitation temperature, and sampling time. A higher ionic strength was achieved by adding a 20% NaCl solution to the sample. The aroma profile of the studied strawberry cultivar consisted of furanone, esters, aldehydes, and carboxylic acids. Optimal results were achieved by adjusting the ionic strength during 15 min of extraction and incubation. The individual compounds were identified using NIST, Wiley libraries, and the “area normalization” method. Full article

(This article belongs to the Special Issue Food Flavor: Molecular Decoding, Multimodal Interaction and Perception)

► Show Figures

Figure 1

15 pages, 2004 KiB

Open AccessArticle

QuEChERS Extraction and Simultaneous Quantification in GC-MS/MS of Hexahydrocannabinol Epimers and Their Metabolites in Whole Blood, Urine, and Oral Fluid

by Annagiulia Di Trana, Giorgia Sprega, Giorgi Kobidze, Omayema Taoussi, Alfredo Fabrizio Lo Faro, Giulia Bambagiotti, Eva Montanari, Maria Sofia Fede, Jeremy Carlier, Anastasio Tini, Francesco Paolo Busardò, Alessandro Di Giorgi and Simona Pichini

Molecules 2024, 29(14), 3440; https://doi.org/10.3390/molecules29143440 - 22 Jul 2024

Viewed by 861

Abstract

Recently, hexahydrocannabinol (HHC) was posed under strict control in Europe due to the increasing HHC-containing material seizures. The lack of analytical methods in clinical laboratories to detect HHC and its metabolites in biological matrices may result in related intoxication underreporting. We developed and [...] Read more.

Recently, hexahydrocannabinol (HHC) was posed under strict control in Europe due to the increasing HHC-containing material seizures. The lack of analytical methods in clinical laboratories to detect HHC and its metabolites in biological matrices may result in related intoxication underreporting. We developed and validated a comprehensive GC-MS/MS method to quantify 9(R)-HHC, 9(S)-HHC, 9αOH-HHC, 9βOH-HHC, 8(R)OH-9(R)-HHC, 8(S)OH-9(S)HHC, 11OH-9(R)HHC, 11OH-9(S)HHC, 11nor-carboxy-9(R)-HHC, and 11nor-carboxy-9(S)-HHC in whole blood, urine, and oral fluid. A novel QuEChERS extraction protocol was optimized selecting the best extraction conditions suitable for all the three matrices. Urine and blood were incubated with β-glucuronidase at 60 °C for 2 h. QuEChERS extraction was developed assessing different ratios of Na₂SO₄:NaCl (4:1, 2:1, 1:1, w/w) to be added to 200 µL of any matrix added with acetonitrile. The chromatographic separation was achieved on a 7890B GC with an HP-5ms column, (30 m, 0.25 mm × 0.25 µm) in 12.50 min. The analytes were detected with a triple-quadrupole mass spectrometer in the MRM mode. The method was fully validated following OSAC guidelines. The method showed good validation parameters in all the matrices. The method was applied to ten real samples of whole blood (n = 4), urine (n = 3), and oral fluid (n = 3). 9(R)-HHC was the prevalent epimer in all the samples (9(R)/9(S) = 2.26). As reported, hydroxylated metabolites are proposed as urinary biomarkers, while carboxylated metabolites are hematic biomarkers. Furthermore, 8(R)OH-9(R)HHC was confirmed as the most abundant metabolite in all urine samples. Full article

(This article belongs to the Section Natural Products Chemistry)

► Show Figures

Figure 1

17 pages, 2026 KiB

Open AccessOpinion

Electrodeposition in Deep Eutectic Solvents: The “Obvious”, the “Unexpected” and the “Wonders”

by Thomas Doneux, Alassane Sorgho, Fousséni Soma, Quentin Rayée and Moussa Bougouma

Molecules 2024, 29(14), 3439; https://doi.org/10.3390/molecules29143439 - 22 Jul 2024

Viewed by 758

Abstract

Deep eutectic solvents (DESs) are attracting considerable attention as non-conventional media for electrodeposition processes. This opinion contribution discusses the debated nature and definition of these solvents as well as some practical considerations of relevance when performing electrodeposition studies in DESs. Using a few [...] Read more.

Deep eutectic solvents (DESs) are attracting considerable attention as non-conventional media for electrodeposition processes. This opinion contribution discusses the debated nature and definition of these solvents as well as some practical considerations of relevance when performing electrodeposition studies in DESs. Using a few illustrative case studies, it is shown that speciation is a key factor determining the electrochemical behaviour of chemical elements in different DESs, and that accounting for the speciation strong similarities can often be found with more conventional or more documented solvents. The need for thermodynamic data is emphasised and it is suggested to expand the composition range of these solvents beyond fixed ratios between the components to exploit the full potentialities of DESs. Full article

(This article belongs to the Special Issue New Advances in Deep Eutectic Solvents)

► Show Figures

Figure 1

17 pages, 4987 KiB

Open AccessArticle

A Series of Lanthanide Coordination Polymers as Luminescent Sensors for Selective Detection of Inorganic Ions and Nitrobenzene

by Miao Wu, Juan Song, Yun-Long Zhou, Hui-Hui Chen, Bo-Feng Duan, Ling-Xia Jin, Chuan-Qing Ren and Jiu-Fu Lu

Molecules 2024, 29(14), 3438; https://doi.org/10.3390/molecules29143438 - 22 Jul 2024

Cited by 1 | Viewed by 826

Abstract

Seven new lanthanide coordination polymers, namely [Ln(cpt)₃H₂O)]n(Ln = La (1), Pr (2), Sm (3), Eu (4), Gd (5), Dy (6), and Er (7)), which were [...] Read more.

Seven new lanthanide coordination polymers, namely [Ln(cpt)₃H₂O)]n(Ln = La (1), Pr (2), Sm (3), Eu (4), Gd (5), Dy (6), and Er (7)), which were synthesized under hydrothermal conditions using 4′-(4-(4-carboxyphenyloxy)phenyl)-4,2′:6′,4′-tripyridine (Hcpt) as the ligand. The crystal structures of these seven complexes were determined using single-crystal X-ray diffraction, and they were found to be isostructural, crystallizing in the triclinic P

\bar{1}

space group. The Ln(III) ions were nine-coordinated with tricapped trigonal prism coordination geometry. The Ln(III) cations were coordinated by carboxylic and pyridine groups from (cpt)⁻ ligands, forming one-dimensional ring-chain structures. Furthermore, the luminescent properties of complexes 1–7 were investigated using fluorescent spectra in the solid state. The fluorescence sensing experiments demonstrated that complex 4 exhibits high selectivity and sensitivity for detecting Co²⁺, Cu²⁺ ions, and nitrobenzene. Moreover, complex 3 shows good capability for detecting Cu²⁺ ions and nitrobenzene. Additionally, the sensing mechanism was also thoroughly examined through theoretical calculations. Full article

► Show Figures

Graphical abstract

25 pages, 3224 KiB

Open AccessReview

Functional Nutrients and Jujube-Based Processed Products in Ziziphus jujuba

by Weitong Cai, Haining Zhuang, Xiaoyu Wang, Xia Fu, Sheng Chen, Lingyun Yao, Min Sun, Huatian Wang, Chuang Yu and Tao Feng

Molecules 2024, 29(14), 3437; https://doi.org/10.3390/molecules29143437 - 22 Jul 2024

Cited by 2 | Viewed by 1133

Abstract

Jujube (Ziziphus jujuba Mill.) is the first tree species in China, with a long history and abundant yield. However, fresh jujubes have a short shelf-life and are not resistant to storage. Therefore, more and more processed jujube products are being studied. These [...] Read more.

Jujube (Ziziphus jujuba Mill.) is the first tree species in China, with a long history and abundant yield. However, fresh jujubes have a short shelf-life and are not resistant to storage. Therefore, more and more processed jujube products are being studied. These processed products can extend the shelf-life of jujubes and attract widespread attention for their rich functional nutrients. This review summarized changes in nutrients of fresh jujube and processed products and the research progress of different preparation methods of jujubes. Meanwhile, the pharmacological effects of bioactive components in jujube-based products were concluded. Jujube and its processed products contain rich polysaccharides, vitamin C, and other functional nutrients, which are beneficial to humans. As the initial processing method for jujubes, vacuum freezing or microwave drying have become the most commonly used and efficient drying methods. Additionally, processed jujube products cannot be separated from the maximum retention of nutrients and innovation of flavor. Fermentation is the main deep-processing method with broad development potential. In the future, chemical components and toxicological evaluation need to be combined with research to bring consumers higher quality functional jujube products and ensure the sustainable development of the jujube industry. Full article

(This article belongs to the Section Chemical Biology)

► Show Figures

Figure 1

19 pages, 5534 KiB

Open AccessArticle

A Globally Accurate Neural Network Potential Energy Surface and Quantum Dynamics Studies on Be⁺(²S) + H₂/D₂ → BeH⁺/BeD⁺ + H/D Reactions

by Zijiang Yang, Furong Cao, Huiying Cheng, Siwen Liu and Jingchang Sun

Molecules 2024, 29(14), 3436; https://doi.org/10.3390/molecules29143436 - 22 Jul 2024

Cited by 1 | Viewed by 811

Abstract

Chemical reactions between Be⁺ ions and H₂ molecules have significance in the fields of ultracold chemistry and astrophysics, but the corresponding dynamics studies on the ground-state reaction have not been reported because of the lack of a global potential energy surface [...] Read more.

Chemical reactions between Be⁺ ions and H₂ molecules have significance in the fields of ultracold chemistry and astrophysics, but the corresponding dynamics studies on the ground-state reaction have not been reported because of the lack of a global potential energy surface (PES). Herein, a globally accurate ground-state BeH₂⁺ PES is constructed using the neural network model based on 18,657 ab initio points calculated by the multi-reference configuration interaction method with the aug-cc-PVQZ basis set. On the newly constructed PES, the state-to-state quantum dynamics calculations of the Be⁺(²S) + H₂(v₀ = 0; j₀ = 0) and Be⁺(²S) + D₂(v₀ = 0; j₀ = 0) reactions are performed using the time-dependent wave packet method. The calculated results suggest that the two reactions are dominated by the complex-forming mechanism and the direct abstraction process at relatively low and high collision energies, respectively, and the isotope substitution has little effect on the reaction dynamics characteristics. The new PES can be used to further study the reaction dynamics of the BeH₂⁺ system, such as the effects of rovibrational excitations and alignment of reactant molecules, and the present dynamics data could provide an important reference for further experimental studies at a finer level. Full article

(This article belongs to the Special Issue Molecular Dynamics Study on Chemical Reactions)

► Show Figures

Figure 1

16 pages, 2332 KiB

Open AccessArticle

Optimization of Extraction Conditions from Gac Fruit and Utilization of Peel-Derived Biochar for Crystal Violet Dye Removal

by Nhat-Thien Nguyen, Pin-Ru Chen, Ru-Hau Ye, Kai-Jen Chuang, Chang-Tang Chang and Gui-Bing Hong

Molecules 2024, 29(14), 3435; https://doi.org/10.3390/molecules29143435 - 22 Jul 2024

Viewed by 863

Abstract

Gac fruit (Momordica cochinchinensis Spreng.) is a prominent source of carotenoids, renowned for its exceptional concentration of these compounds. This study focuses on optimizing the extraction of active components from the aril of gac fruit by evaluating the effects of extraction temperature, [...] Read more.

Gac fruit (Momordica cochinchinensis Spreng.) is a prominent source of carotenoids, renowned for its exceptional concentration of these compounds. This study focuses on optimizing the extraction of active components from the aril of gac fruit by evaluating the effects of extraction temperature, solid–liquid ratio, and extraction time. The primary objective is to maximize the yield of gac oil while assessing its antioxidant capacity. To analyze the kinetics of the solid–liquid extraction process, both first-order and second-order kinetic models were employed, with the second-order model providing the best fit for the experimental data. In addition, the potential of gac fruit peel as a precursor for biochar production was investigated through carbonization. The resultant biochars were evaluated for their efficacy in adsorbing crystal violet (CV) dye from aqueous solutions. The adsorption efficiency of the biochars was found to be dependent on the carbonization temperature, with the highest efficiency observed for BCMC550 (91.72%), followed by BCM450 (81.35%), BCMC350 (78.35%), and BCMC250 (54.43%). The adsorption isotherm data conformed well to the Langmuir isotherm model, indicating monolayer adsorption behavior. Moreover, the adsorption kinetics were best described by the pseudo-second-order model. These findings underscore the potential of gac fruit and its byproducts for diverse industrial and environmental applications, highlighting the dual benefits of optimizing gac oil extraction and utilizing the peel for effective dye removal. Full article

► Show Figures

Figure 1

16 pages, 2112 KiB

Open AccessArticle

Palladium-Catalyzed Tsuji–Trost-Type Reaction of 3-Indolylmethylacetates with O, and S Soft Nucleophiles

by Antonia Iazzetti, Antonio Arcadi, Marco Chiarini, Giancarlo Fabrizi, Antonella Goggiamani, Federico Marrone, Andrea Serraiocco and Roberta Zoppoli

Molecules 2024, 29(14), 3434; https://doi.org/10.3390/molecules29143434 - 22 Jul 2024

Viewed by 699

Abstract

The chemical valorization of widespread molecules in renewable sources is a field of research widely investigated in the last decades. In this context, we envisaged that indole-3-carbinol, present in different Cruciferae plants, could be a readily available building block for the synthesis of [...] Read more.

The chemical valorization of widespread molecules in renewable sources is a field of research widely investigated in the last decades. In this context, we envisaged that indole-3-carbinol, present in different Cruciferae plants, could be a readily available building block for the synthesis of various classes of indoles through a palladium-catalyzed Tsuji–Trost-type reaction with O and S soft nucleophiles. The regiochemical outcome of this high-yielding functionalization shows that the nucleophilic substitution occurs only at the benzylic position. Interestingly, with this protocol, the sulfonyl unit could be appended to the indole nucleus, providing convenient access to new classes of molecules with potential bioactivity. Full article

(This article belongs to the Special Issue New Metal Catalysts for Sustainable Chemistry)

► Show Figures

Figure 1

17 pages, 6851 KiB

Open AccessArticle

Enhancing Sulfidization and Flotation of Smithsonite Using Eco-Friendly Triethanolamine: Insights from Experimental and Simulation Studies

by Song Zhang, Guanyu Liang, Yongjun Xian and Shuming Wen

Molecules 2024, 29(14), 3433; https://doi.org/10.3390/molecules29143433 - 22 Jul 2024

Viewed by 867

Abstract

Triethanolamine (TEA) is a promising eco-friendly alternative to inorganic ammonia for enhancing surface sulfidization and flotation recovery of smithsonite. Micro-flotation experiments revealed an enhancement in smithsonite recovery to 95.21% with TEA modification, comparable to the results obtained using ammonia. The mechanisms behind the [...] Read more.

Triethanolamine (TEA) is a promising eco-friendly alternative to inorganic ammonia for enhancing surface sulfidization and flotation recovery of smithsonite. Micro-flotation experiments revealed an enhancement in smithsonite recovery to 95.21% with TEA modification, comparable to the results obtained using ammonia. The mechanisms behind the ability of TEA to enhance the sulfidization process were investigated through surface analysis and molecular dynamics simulations. TEA modification increased the content of sulfidization products, the proportion of crucial S₂²⁻ in adsorbed products, and the thickness and size of the sulfidization product layer. The complexation of TEA with Zn sites formed positively charged Zn–TEA complexes that adsorb onto the smithsonite surface. These complexes promoted negatively charged HS⁻ adsorption, creating a multi-layered adsorption structure. Moreover, TEA modification reduced the total energy required for the sulfidization. These findings open up new possibilities for using eco-friendly reagents in mineral processing, highlighting the potential of TEA in green mineral processing practices. Full article

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

► Show Figures

Graphical abstract

15 pages, 2759 KiB

Open AccessArticle

Multicomponent Synthesis of New Fluorescent Boron Complexes Derived from 3-Hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde

by Viktorija Savickienė, Aurimas Bieliauskas, Sergey Belyakov, Eglė Arbačiauskienė and Algirdas Šačkus

Molecules 2024, 29(14), 3432; https://doi.org/10.3390/molecules29143432 - 22 Jul 2024

Viewed by 1209

Abstract

Novel fluorescent pyrazole-containing boron (III) complexes were synthesized employing a one-pot three-component reaction of 3-hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-aminobenzenecarboxylic acids, and boronic acids. The structures of the novel heterocyclic compounds were confirmed using ¹H-, ¹³C-, ¹⁵N-, ¹⁹F-, and ¹¹B-NMR, [...] Read more.

Novel fluorescent pyrazole-containing boron (III) complexes were synthesized employing a one-pot three-component reaction of 3-hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-aminobenzenecarboxylic acids, and boronic acids. The structures of the novel heterocyclic compounds were confirmed using ¹H-, ¹³C-, ¹⁵N-, ¹⁹F-, and ¹¹B-NMR, IR spectroscopy, HRMS, and single-crystal X-ray diffraction data. The photophysical properties of the obtained iminoboronates were investigated using spectroscopic techniques, such as UV–vis and fluorescence spectroscopies. Compounds display main UV–vis absorption maxima in the blue region, and fluorescence emission maxima are observed in the green region of the visible spectrum. It was revealed that compounds exhibit fluorescence quantum yield up to 4.3% in different solvents and demonstrate an aggregation-induced emission enhancement effect in mixed THF–water solutions. Full article

(This article belongs to the Special Issue Advances in Functional Organic Dye Chemistry)

► Show Figures

Graphical abstract

20 pages, 2429 KiB

Open AccessArticle

Analysis of Chemical Composition, Antioxidant Activity, and Toxicity of Essential Oil from Virola sebifera Aubl (Myristicaceae)

by Jorddy Neves Cruz, Mozaniel Santana de Oliveira, Oberdan Oliveira Ferreira, Antonio Rafael Quadros Gomes, Suraj N. Mali, Soluan Felipe Melo Pereira, Sabah Ansar, Cleydson Breno Rodrigues dos Santos, Rafael Rodrigues Lima and Eloisa Helena Aguiar de Andrade

Molecules 2024, 29(14), 3431; https://doi.org/10.3390/molecules29143431 - 22 Jul 2024

Viewed by 1101

Abstract

Volatile oils or essential oils (EOs) were extracted from three V. sebifera samples (labeled as A, B, and C) in September 2018 and February 2019; the extraction process involved hydrodistillation of the leaves. The chemical compositions of the EOs were analyzed using gas [...] Read more.

Volatile oils or essential oils (EOs) were extracted from three V. sebifera samples (labeled as A, B, and C) in September 2018 and February 2019; the extraction process involved hydrodistillation of the leaves. The chemical compositions of the EOs were analyzed using gas chromatography-mass spectrometry (GC/MS). The volatile components were identified by comparing their retention indices and mass spectra with standard substances documented in the literature (ADAMS). The antioxidant activity of the EOs was evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), while their toxicity was assessed using Artemia salina Leach. Molecular docking was utilized to examine the interaction between the major constituents of V. sebifera EO and acetylcholinesterase (AChE), a molecular target linked to toxicity in A. salina models. The EO obtained from specimen A, collected in September 2018, was characterized by being primarily composed of (E,E)-α-farnesene (47.57%), (E)-caryophyllene (12.26%), and α-pinene (6.93%). Conversely, the EO from specimen A, collected in February 2019, was predominantly composed of (E,E)-α-farnesene (42.82%), (E)-caryophyllene (16.02%), and bicyclogermacrene (8.85%), the EO from specimen B, collected in September 2018, primarily contained (E,E)-α-farnesene (47.65%), (E)-caryophyllene (19.67%), and α-pinene (11.95%), and the EO from the leaves collected in February 2019 was characterized by (E,E)-α-farnesene (23.57%), (E)-caryophyllene (19.34%), and germacrene D (7.33%). The EO from the leaves collected in September 2018 contained (E,E)-α-farnesene (26.65%), (E)-caryophyllene (15.7%), and germacrene D (7.72%), while the EO from the leaves collected in February 2019 was primarily characterized by (E,E)-α-farnesene (37.43%), (E)-caryophyllene (21.4%), and α-pinene (16.91%). Among these EOs, sample B collected in February 2019 demonstrated the highest potential for inhibiting free radicals, with an inhibition rate of 34.74%. Conversely, the EOs from specimen A exhibited the highest toxic potentials, with an lethal concentration 50 (LC₅₀) value of 57.62 ± 1.53 µg/mL, while specimen B had an LC₅₀ value of 74.72 ± 2.86 µg/mL. Molecular docking results suggested that hydrophobic interactions significantly contributed to the binding of the major compounds in the EO from sample B to the binding pocket of AChE. Full article

(This article belongs to the Special Issue Chemical Analyses and Applications of Essential Oils)

► Show Figures

Figure 1

19 pages, 2869 KiB

Open AccessArticle

Modification of Silica with Sucrose and Ammonium Fluoride Agents: A Facile Route to Prepare Supports of Iridium Catalysts for Hydrogenation Reaction

by Ewa Janiszewska, Mariusz Pietrowski and Michał Zieliński

Molecules 2024, 29(14), 3430; https://doi.org/10.3390/molecules29143430 - 22 Jul 2024

Viewed by 817

Abstract

Mesoporous silica materials were synthesized using inexpensive and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose and the products of its chemical transformation during synthesis (e.g., furfural polymer) significantly affected the structure of the obtained porous [...] Read more.

Mesoporous silica materials were synthesized using inexpensive and environmentally friendly sucrose as a porogeneous agent. It was found that the presence of sucrose and the products of its chemical transformation during synthesis (e.g., furfural polymer) significantly affected the structure of the obtained porous silica. The influence of synthesis conditions (pH, temperature, time) on the textural properties of the final materials was determined. Samples obtained in an acidic medium, at pH = 1, and treated at room temperature, yielded products with a large surface area and a narrow pore size distribution in the range of 2–5 nm, while the synthesis at pH = 8 allowed for the formation of mesoporous systems with pores in the range of 14–20 nm. To generate acidity, the silicas were modified with an ammonium fluoride solution and then used as supports for iridium catalysts in a hydrogenation reaction, with toluene as a model hydrocarbon. The influence of parameters such as specific surface area, support acidity, and iridium dispersion on catalytic activity was determined. It was shown that modification with sucrose improved the porous structure, and NH₄F modification generated acidity. These parameters favored better reducibility and dispersion of the active phase, resulting in higher activity of the catalysts in the studied hydrogenation reaction. Full article

(This article belongs to the Special Issue Porous and Nanoporous Materials in Heterogeneous Catalysis)

► Show Figures

Graphical abstract

13 pages, 2423 KiB

Open AccessArticle

HOO^• as the Chain Carrier for the Autocatalytic Photooxidation of Benzylic Alcohols

by Xiao-Yu Wang, Huan-E Lao, Hao-Yue Zhang, Yi Wang, Qing Zhang, Jie-Qing Wu, Yu-Feng Li, Hong-Jun Zhu, Jian-You Mao and Yi Pan

Molecules 2024, 29(14), 3429; https://doi.org/10.3390/molecules29143429 - 22 Jul 2024

Viewed by 1066

Abstract

The oxidation of benzylic alcohols is an important transformation in modern organic synthesis. A plethora of photoredox protocols have been developed to achieve the aerobic oxidation of alcohols into carbonyls. Recently, several groups described that ultraviolet (UV) or purple light can initiate the [...] Read more.

The oxidation of benzylic alcohols is an important transformation in modern organic synthesis. A plethora of photoredox protocols have been developed to achieve the aerobic oxidation of alcohols into carbonyls. Recently, several groups described that ultraviolet (UV) or purple light can initiate the aerobic oxidation of benzylic alcohols in the absence of an external catalyst, and depicted different mechanisms involving the photoinduction of ^•O₂⁻ as a critical reactive oxygen species (ROS). However, based on comprehensive mechanistic investigations, including control experiments, radical quenching experiments, EPR studies, UV–vis spectroscopy, kinetics studies, and density functional theory calculations (DFT), we elucidate here that HOO^•, which is released via the H₂O₂ elimination of α-hydroxyl peroxyl radicals [ArCR(OH)OO^•], serves as the real chain carrier for the autocatalytic photooxidation of benzylic alcohols. The mechanistic ambiguities depicted in the precedent literature are clarified, in terms of the crucial ROS and its evolution, the rate-limiting step, and the primary radical cascade. This work highlights the necessity of stricter mechanistic analyses on UV-driven oxidative reactions that involve aldehydes’ (or ketones) generation. Full article

(This article belongs to the Section Photochemistry)

► Show Figures

Figure 1

16 pages, 4029 KiB

Open AccessArticle

Pulsed Electric Field-Assisted Extraction of Inulin from Ecuadorian Cabuya (Agave americana)

by Alejandra Rivera, Marcelo Pozo, Vanessa E. Sánchez-Moreno, Edwin Vera and Lorena I. Jaramillo

Molecules 2024, 29(14), 3428; https://doi.org/10.3390/molecules29143428 - 22 Jul 2024

Viewed by 859

Abstract

Inulin is a carbohydrate that belongs to fructans; due to its health benefits, it is widely used in the food and pharmaceutical industries. In this research, cabuya (Agave americana) was employed to obtain inulin by pulsed electric field-assisted extraction (PEFAE) and [...] Read more.

Inulin is a carbohydrate that belongs to fructans; due to its health benefits, it is widely used in the food and pharmaceutical industries. In this research, cabuya (Agave americana) was employed to obtain inulin by pulsed electric field-assisted extraction (PEFAE) and FTIR analysis confirmed its presence. The influence of PEFAE operating parameters, namely, electric field strength (1, 3 and 5 kV/cm), pulse duration (0.1, 0.2 and 0.5 ms), number of pulses (10,000, 20,000 and 40,000) and work cycle (20, 50 and 80%) on the permeabilization index and energy expenditure were tested. Also, once the operating conditions for PEFAE were set, the temperature for conventional extraction (CE) and PEFAE were defined by comparing extraction kinetics. The cabuya meristem slices were exposed to PEFAE to obtain extracts that were quantified, purified and concentrated. The inulin was isolated by fractional precipitation with ethanol to be characterized. The highest permeabilization index and the lowest energy consumption were reached at 5 kV/cm, 0.5 ms, 10,000 pulses and 20%. The same extraction yield and approximately the same amount of inulin were obtained by PEFAE at 60 °C compared to CE at 80 °C. Despite, the lower amount of inulin obtained by PEFAE in comparison to CE, its quality was better because it is mainly constituted of inulin of high average polymerization degree with more than 38 fructose units. In addition, TGA analyses showed that inulin obtained by PEFAE has a lower thermal degradation rate than the obtained by CE and to the standard. Full article

► Show Figures

Figure 1

19 pages, 4692 KiB

Open AccessArticle

Phytochemical Investigation of Carex praecox Schreb. and ACE-Inhibitory Activity of Oligomer Stilbenes of the Plant

by Csilla Zsuzsanna Dávid, Norbert Kúsz, Orinamhe Godwin Agbadua, Róbert Berkecz, Annamária Kincses, Gabriella Spengler, Attila Hunyadi, Judit Hohmann and Andrea Vasas

Molecules 2024, 29(14), 3427; https://doi.org/10.3390/molecules29143427 - 22 Jul 2024

Cited by 2 | Viewed by 955

Abstract

Phenolic compounds are the main special metabolites of Cyperaceae species from phytochemical, pharmacological, and chemotaxonomical points of view. The present study focused on the isolation, structure determination, and pharmacological investigation of constituents from Carex praecox. Twenty-six compounds, including lignans, stilbenes, flavonoids, megastigmanes, [...] Read more.

Phenolic compounds are the main special metabolites of Cyperaceae species from phytochemical, pharmacological, and chemotaxonomical points of view. The present study focused on the isolation, structure determination, and pharmacological investigation of constituents from Carex praecox. Twenty-six compounds, including lignans, stilbenes, flavonoids, megastigmanes, chromenes, and phenylpropanoids, were identified from the methanol extract of the plant. Five of these compounds, namely, carexines A–E, are previously undescribed natural products. All compounds were isolated for the first time from C. praecox. The ACE-inhibitory activity of seven stilbenoid compounds was tested, and (–)-hopeaphenol proved to be the most active (IC₅₀ 7.7 ± 0.9 μM). The enzyme–kinetic studies revealed a mixed-type inhibition; therefore, domain-specific studies were also conducted. The in silico docking of (–)-hopeaphenol to the ACE affirmed some favorable interactions. In addition, the antiproliferative and antibacterial effects of some compounds were also evaluated. Full article

(This article belongs to the Special Issue Bioactive Compounds from Natural Sources III)

► Show Figures

Graphical abstract

8 pages, 1063 KiB

Open AccessArticle

Copper(I)-Catalyzed Formal [4 + 2] Cyclocondensation of ortho-Hydroxybenzyl Alcohol, Aromatic Terminal Alkynes, and Sulfonyl Azides: An Alternative Approach to 2-Sulfonyliminocoumarins

by Dost Muhammad Khan, Jiaying Lv and Ruimao Hua

Molecules 2024, 29(14), 3426; https://doi.org/10.3390/molecules29143426 - 22 Jul 2024

Viewed by 772

Abstract

In this paper, an alternative and efficient copper(I)-catalyzed synthesis of 2-sulfonyliminocoumarins is developed through a three-component reaction of ortho-hydroxybenzyl alcohol, alkynes, and p-toluenesulfonyl azide. The proposed route for access to the 2-iminocoumarin ring involves a [4 + 2] hetero-Diels-Alder reaction between [...] Read more.

In this paper, an alternative and efficient copper(I)-catalyzed synthesis of 2-sulfonyliminocoumarins is developed through a three-component reaction of ortho-hydroxybenzyl alcohol, alkynes, and p-toluenesulfonyl azide. The proposed route for access to the 2-iminocoumarin ring involves a [4 + 2] hetero-Diels-Alder reaction between ortho-quinone methide and ketenimine intermediates generated in situ. Full article

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

► Show Figures

Scheme 1

13 pages, 1816 KiB

Open AccessArticle

Palladium(II) and Platinum(II) Complexes Bearing ONS-Type Pincer Ligands: Synthesis, Characterization and Catalytic Investigations

by Alfonso Castiñeiras and Isabel García-Santos

Molecules 2024, 29(14), 3425; https://doi.org/10.3390/molecules29143425 - 22 Jul 2024

Viewed by 813

Abstract

This work describes the synthesis of eight new Pd(II) and Pt(II) complexes with the general formula [M(TSC)Cl], where TSC represents the 4N-monosubstituted thiosemicarbazone derived from 2-acetylpyridine N-oxide with the substituents CH₃ (H4MLO), C₂H₅ (H4ELO), phenyl (H4PLO) and (CH₃ [...] Read more.

This work describes the synthesis of eight new Pd(II) and Pt(II) complexes with the general formula [M(TSC)Cl], where TSC represents the 4N-monosubstituted thiosemicarbazone derived from 2-acetylpyridine N-oxide with the substituents CH₃ (H4MLO), C₂H₅ (H4ELO), phenyl (H4PLO) and (CH₃)₂ (H4DMLO). These complexes have been characterized by elemental analysis, molar conductivity, IR spectroscopy, ¹H, ¹³C, ¹⁹⁵Pt and ESI-MS. The complexes exhibit a square planar geometry around the metallic center coordinated by a thiosemicarbazone molecule acting as a donor ONS-type pincer ligand and by a chloride, as confirmed by the molecular structures of the complexes, [Pd(4ELO)Cl] (3) and [Pd(4PLO)Cl] (5), determined by single-crystal X-ray diffraction. The ¹⁹⁵Pt NMR spectra of the complexes of formulae [Pt(4PLO)Cl] (6) and [Pt(4DMLO)Cl] (8) in DMSO show a single signal at −2420.4 ppm, confirming the absence of solvolysis products. Complexes 3 and 5 have been tested as catalysts in the Suzuki–Miyaura cross-coupling reactions of aryl bromides with phenylboronic acid, with yields of between 50 and 90% Full article

(This article belongs to the Special Issue Recent Advances in Coordination Chemistry of Metal Complexes)

► Show Figures

Graphical abstract

13 pages, 2577 KiB

Open AccessArticle

Hydrogen Atom Abstraction and Reduction Study of 21-Thiaporphyrin and 21,23-Dithiaporphyrin

by Xiao-Rui Ren, Kang Xing, Teng Liu, Ronghui Cao, Li-Long Dang, Feng Bai and Peng-Cheng Duan

Molecules 2024, 29(14), 3424; https://doi.org/10.3390/molecules29143424 - 22 Jul 2024

Viewed by 998

Abstract

The metal-free porphyrins protonation has gained interest over five decades because its structure modification and hardly monoacid intermediate isolation. Here, upon the hydrogen atom abstraction processes, one step diproptonated H₃STTP(BF₄)₂ (STTP = 5,10,15,20-tetraphenyl-21-thiaporphyrin) (3) and stepwise [...] Read more.

The metal-free porphyrins protonation has gained interest over five decades because its structure modification and hardly monoacid intermediate isolation. Here, upon the hydrogen atom abstraction processes, one step diproptonated H₃STTP(BF₄)₂ (STTP = 5,10,15,20-tetraphenyl-21-thiaporphyrin) (3) and stepwise protonated HS₂TTPSbCl₆ (5) and diprotonated H₂S₂TTP(BF₄)₂ (6) (S₂TTP = 5,10,15,20-tetraphenyl-21,23-thiaporphyrin) compounds were obtained using HSTTP and S₂TTP with oxidants. The closed-shell protonated compounds were fully characterized using XRD, UV-vis, IR and NMR spectra. In addition, the reduced 19π compounds [K(2,2,2)]HSTTP (2) and [K(2,2,2)]S₂TTP (7) were synthesized by the ligands with reductant KC₈ in THF solution. These two open-shell compounds were characterized with UV-vis, IR and EPR spectroscopies. The semiempirical ZINDO/S method was employed to analyze the HOMO/LUMO gap lever and identify the electronic transitions of the UV-vis spectra of the closed- and open-shell porphyrin compounds. Full article

► Show Figures

Graphical abstract

14 pages, 4396 KiB

Open AccessArticle

Deep Eutectic Solvents-Based Ultrasonic-Assisted Dispersive Liquid–Liquid Microextraction for the Determination of Organophosphorus Pesticides in Honeysuckle Dew Samples

by Kangmiao Guo, Xiaokun Wu, Fan Zhang, Ying Cao, Zenglei Tan, Shuwen Xiao and Lijie Wu

Molecules 2024, 29(14), 3423; https://doi.org/10.3390/molecules29143423 - 21 Jul 2024

Cited by 1 | Viewed by 1092

Abstract

A deep eutectic solvent (DES) with the ability to change from hydrophilic to hydrophobic was designed and synthesized and applied to the determination of organophosphorus (OPP) pesticides in honeysuckle dew samples. Choline chloride, phenol, and tetrahydrofuran (THF) were used as the hydrogen bond [...] Read more.

A deep eutectic solvent (DES) with the ability to change from hydrophilic to hydrophobic was designed and synthesized and applied to the determination of organophosphorus (OPP) pesticides in honeysuckle dew samples. Choline chloride, phenol, and tetrahydrofuran (THF) were used as the hydrogen bond acceptor, hydrogen bond donor, and demulsifier, respectively. Eight OPP pesticides were extracted by DES coupled with ultrasonic-assisted extraction (UA) and then chromatographed by GC-MS. DES used as an extract solvent has the advantages of high extraction efficiency, low cost, and environmental protection. Furthermore, DES is compatible with GC-MS. The single factor experiment design and Box–Behnken design (BBD) were applied to the optimization of experimental factors, including the type and composition of extraction solvent, type of demulsifier solvent, the volume of DES and THF, pH of sample solution, and ultrasonic time. Under the optimum experimental conditions, the high degree of linearity from 0.1 to 20.0 ng mL⁻¹ (R² ≥ 0.9989), the limits of detection from 0.014 to 0.051 ng mL⁻¹ (S/N = 3), and the recoveries of analytes from 81.4 to 104.4% with relative standard deviation below 8.6%. In addition, the adsorption mechanism of OPPs on DES was explored by adsorption kinetic studies. These results have demonstrated that the present method has offered an effective, accurate, and sensitive methodology for OPP pesticides in honeysuckle dew samples, and this method provides a reference for the detection of pesticide residues in traditional Chinese medicine. Full article

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

► Show Figures

Graphical abstract

14 pages, 7369 KiB

Open AccessArticle

New Series of Hydrogen-Bonded Liquid Crystal with High Birefringence and Conductivity

by Manel Ben Salah, Lotfi Saadaoui, Taoufik Soltani, Naoufel Ben Hamadi, Ahlem Guesmi and Ulrich Maschke

Molecules 2024, 29(14), 3422; https://doi.org/10.3390/molecules29143422 - 21 Jul 2024

Viewed by 1107

Abstract

Liquid crystals with high dielectric anisotropy, low operational thresholds, and significant birefringence (Δn) represent a key focus in soft matter research. This work introduces a novel series of hydrogen-bonded liquid crystals (HBLCs) derived from 4-n-alkoxybenzoic, 4-alkoxy-3-fluorobenzoic derivatives (nOBAF), 4-alkoxy-2,3-fluorobenzoic derivatives (nOBAFF), [...] Read more.

Liquid crystals with high dielectric anisotropy, low operational thresholds, and significant birefringence (Δn) represent a key focus in soft matter research. This work introduces a novel series of hydrogen-bonded liquid crystals (HBLCs) derived from 4-n-alkoxybenzoic, 4-alkoxy-3-fluorobenzoic derivatives (nOBAF), 4-alkoxy-2,3-fluorobenzoic derivatives (nOBAFF), and 2-fluoro-4-nitrobenzoic acid. The HBLCs were characterized using Fourier transform infrared spectroscopy, and their thermal behavior was evaluated via differential scanning calorimetry. Optical observations were conducted using polarized optical microscopy. The results indicate that mixtures containing benzoic acid with a bilateral fluorine substituent exhibit both SmA and SmC phases, while those with a unilateral fluorine substituent exhibit nematic and SmA phases. Moreover, an increase in the length of the alkoxy chain results in an expanded mesophase temperature range. This study demonstrates that the presence of a fluorine substituent and the incorporation of an NO₂ group in the molecular structure result in an increase in dielectric permittivity, DC conductivity, dielectric anisotropy, and birefringence. Full article

(This article belongs to the Special Issue Liquid Crystals II)

► Show Figures

Figure 1

14 pages, 1431 KiB

Open AccessArticle

Modulation of the Antimelanoma Activity Imparted to Artemisinin Hybrids by the Monoterpene Counterpart

by Elisa De Marchi, Silvia Filippi, Silvia Cesarini, Beatrice Di Maio, Bruno Mattia Bizzarri, Raffaele Saladino and Lorenzo Botta

Molecules 2024, 29(14), 3421; https://doi.org/10.3390/molecules29143421 - 21 Jul 2024

Viewed by 884

Abstract

Molecular hybridization is a widely used strategy in drug discovery and development processes that consists of the combination of two bioactive compounds toward a novel entity. In the current study, two libraries of hybrid derivatives coming from the linkage of sesquiterpene counterparts dihydroartemisinin [...] Read more.

Molecular hybridization is a widely used strategy in drug discovery and development processes that consists of the combination of two bioactive compounds toward a novel entity. In the current study, two libraries of hybrid derivatives coming from the linkage of sesquiterpene counterparts dihydroartemisinin and artesunic acid, with a series of monoterpenes, were synthesized and evaluated by cell viability assay on primary and metastatic melanoma cell lines. Almost all the obtained compounds showed micromolar antimelanoma activity and selectivity toward the metastatic form of this cancer. Four hybrid derivatives containing perillyl alcohol, citronellol, and nerol as monoterpene counterpart emerged as the best compounds of the series, with nerol being active in combination with both sesquiterpenes, dihydroartemisinin and artesunic acid. Preliminary studies on the mechanism of action have shown the dependence of the pharmacological activity of newly synthesized hybrids on the formation of carbon- and oxygen-centered radical species. This study demonstrated the positive modulation of the pharmacodynamic effect of artemisinin semisynthetic derivatives dihydroartemisinin and artesunic acid due to the hybridization with monoterpene counterparts. Full article

(This article belongs to the Section Organic Chemistry)

► Show Figures

Graphical abstract

21 pages, 2478 KiB

Open AccessArticle

Ru(II)-Catalyzed Asymmetric Transfer Hydrogenation of α-Alkyl-β-Ketoaldehydes via Dynamic Kinetic Resolution

by Daiene P. Lapa, Leticia H. S. Araújo, Sávio R. Melo, Paulo R. R. Costa and Guilherme S. Caleffi

Molecules 2024, 29(14), 3420; https://doi.org/10.3390/molecules29143420 - 21 Jul 2024

Viewed by 984

Abstract

The (R,R)-Teth-TsDPEN-Ru(II) complex promoted the one-pot double C=O reduction of α-alkyl-β-ketoaldehydes through asymmetric transfer hydrogenation/dynamic kinetic resolution (ATH-DKR) under mild conditions. In this process, ten anti-2-benzyl-1-phenylpropane-1,3-diols (85:15 to 92:8 dr) were obtained in good yields (41–87%) and excellent [...] Read more.

The (R,R)-Teth-TsDPEN-Ru(II) complex promoted the one-pot double C=O reduction of α-alkyl-β-ketoaldehydes through asymmetric transfer hydrogenation/dynamic kinetic resolution (ATH-DKR) under mild conditions. In this process, ten anti-2-benzyl-1-phenylpropane-1,3-diols (85:15 to 92:8 dr) were obtained in good yields (41–87%) and excellent enantioselectivities (>99% ee for all compounds). Notably, the preferential reduction of the aldehyde moiety led to the in situ formation of 2-benzyl-3-hydroxy-1-phenylpropan-1-one intermediates. These intermediates played a crucial role in enhancing both reactivity and stereoselectivity through hydrogen bonding. Full article

(This article belongs to the Special Issue Recent Advances of Catalytic Asymmetric Synthesis)

► Show Figures

Figure 1

16 pages, 6116 KiB

Open AccessArticle

Preparation and Properties of High Sound-Absorbing Porous Ceramics Reinforced by In Situ Mullite Whisker from Construction Waste

by Kaihui Hua, Xiaobing Chen, Anze Shui, Xiuan Xi, Pinhai Gao, Yu Zheng and Chuncan He

Molecules 2024, 29(14), 3419; https://doi.org/10.3390/molecules29143419 - 21 Jul 2024

Cited by 1 | Viewed by 1103

Abstract

Porous sound absorption ceramic is one of the most promising materials for effectively eliminating noise pollution. However, its high production cost and low mechanical strength limit its practical applications. In this work, low-cost and in situ mullite whisker-reinforced porous sound-absorbing ceramics were prepared [...] Read more.

Porous sound absorption ceramic is one of the most promising materials for effectively eliminating noise pollution. However, its high production cost and low mechanical strength limit its practical applications. In this work, low-cost and in situ mullite whisker-reinforced porous sound-absorbing ceramics were prepared using recyclable construction waste and Al₂O₃ powder as the main raw materials, and AlF₃ and CeO₂ as the additives, respectively. The effects of CeO₂ content, AlF₃ content, and sintering temperature on the microstructure and properties of the porous ceramics were systematically investigated. The results showed that a small amount of CeO₂ significantly promoted the growth of elongated mullite crystals in the resultant porous ceramics, decreased the growth temperature of the mullite whiskers, and significantly increased the biaxial flexural strength. When 2 wt.% CeO₂ and 12 wt.% AlF₃ were added to the system, mullite whiskers were successfully obtained at a sintering temperature of 1300 °C for 1 h, which exhibited excellent properties, including an open porosity of 56.4 ± 0.6%, an average pore size of 1.32–2.54 μm, a biaxial flexural strength of 23.7 ± 0.9 MPa, and a sound absorption coefficient of >0.8 at 800–4000 Hz. Full article

(This article belongs to the Special Issue Modern Materials in Energy Storage and Conversion)

► Show Figures

Graphical abstract

13 pages, 1579 KiB

Open AccessCommunication

A Nickel/Organoboron-Catalyzed Coupling of Aryl Bromides with Sodium Sulfinates: The Synthesis of Sulfones under Visible Light

by Siyi Ding, Weina Tian, Qiaohuan Lv, Zongcheng Miao and Liang Xu

Molecules 2024, 29(14), 3418; https://doi.org/10.3390/molecules29143418 - 21 Jul 2024

Viewed by 841

Abstract

An efficient cross-coupling of aryl bromides with sodium sulfinates, using an organoboron photocatalyst with nickel, is described herein. Under the irradiation of white light, this dually catalytic system enables the synthesis of a series of sulfone compounds in moderate to good yields. A [...] Read more.

An efficient cross-coupling of aryl bromides with sodium sulfinates, using an organoboron photocatalyst with nickel, is described herein. Under the irradiation of white light, this dually catalytic system enables the synthesis of a series of sulfone compounds in moderate to good yields. A broad range of functional groups and heteroaromatic compounds is tolerated under these reaction conditions. The use of an organoboron photocatalyst highlights a sustainable alternative to iridium or ruthenium complexes. These findings contribute to the field of photochemistry and provide a greener approach to sulfone synthesis. Full article

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

► Show Figures

Figure 1

17 pages, 5056 KiB

Open AccessArticle

Praseodymium-Doped Cr₂O₃ Prepared by In Situ Pyrolysis of MIL-101(Cr) for Highly Efficient Catalytic Oxidation of 1,2-Dichloroethane

by Pengfei Zhu, Zhaoxia Hu and Shouwen Chen

Molecules 2024, 29(14), 3417; https://doi.org/10.3390/molecules29143417 - 21 Jul 2024

Viewed by 888

Abstract

The development of economical catalysts that exhibit both high activity and durability for chlorinated volatile organic compounds (CVOCs) elimination remains a challenge. The oxidizing and acidic sites play a crucial role in the oxidation process of CVOCs; herein, praseodymium (Pr) was introduced into [...] Read more.

The development of economical catalysts that exhibit both high activity and durability for chlorinated volatile organic compounds (CVOCs) elimination remains a challenge. The oxidizing and acidic sites play a crucial role in the oxidation process of CVOCs; herein, praseodymium (Pr) was introduced into CrOx catalysts via in situ pyrolysis of MIL-101(Cr). With the decomposition of the ligand, a mixed micro-mesoporous structure was formed within the M-Cr catalyst, thereby reducing the contact resistance between catalyst active sites and the 1,2-dichloroethane molecule. Moreover, the synergistic interaction between chromium and praseodymium facilitates O_β species and acidic sites, significantly enhancing the low-temperature catalytic performance and durability of the M-PrCr catalyst for 1,2-dichloroethane (1,2-DCE) oxidation. The M-30PrCr catalyst possess enhanced active oxygen sites and acid sites, thereby exhibiting the highest catalytic activity and stability. This study may provide a novel and promising strategy for practical applications in the elimination of 1,2-DCE. Full article

► Show Figures

Figure 1

16 pages, 3569 KiB

Open AccessArticle

Suitable Stereoscopic Configuration of Electrolyte Additive Enabling Highly Reversible and High—Rate Zn Anodes

by Binrui Xu, Yong Liu, Bo Zhao, Haoming Li, Min Liu, Huanxiao Mai and Quanan Li

Molecules 2024, 29(14), 3416; https://doi.org/10.3390/molecules29143416 - 21 Jul 2024

Cited by 1 | Viewed by 797

Abstract

Electrolyte additive engineering is a crucial method for enhancing the performance of aqueous zinc—ion batteries (AZIBs). Recently, most research predominantly focuses on the role of functional groups in regulating electrolytes, often overlooking the impact of molecule stereoscopic configuration. Herein, two isomeric sugar alcohols, [...] Read more.

Electrolyte additive engineering is a crucial method for enhancing the performance of aqueous zinc—ion batteries (AZIBs). Recently, most research predominantly focuses on the role of functional groups in regulating electrolytes, often overlooking the impact of molecule stereoscopic configuration. Herein, two isomeric sugar alcohols, mannitol and sorbitol, are employed as electrolyte additives to investigate the impact of the stereoscopic configuration of additives on the ZnSO₄ electrolyte. Experimental analysis and theoretical calculations reveal that the primary factor for improving Zn anode performance is the regulation of the solvation sheath by these additives. Among the isomers, mannitol exhibits stronger binding energies with Zn²⁺ ions and water molecules due to its more suitable stereoscopic configuration. These enhanced bindings allow mannitol to coordinate with Zn²⁺, contributing to solvation structure formation and reducing the active H₂O molecules in the bulk electrolyte, resulting in suppressed parasitic reactions and inhibited dendritic growth. As a result, the zinc electrodes in mannitol—modified electrolyte exhibit excellent cycling stability of 1600 h at 1 mA cm⁻² and 900 h at 10 mA cm⁻², respectively. Hence, this study provides novel insights into the importance of suitable stereoscopic molecule configurations in the design of electrolyte additives for highly reversible and high—rate Zn anodes. Full article

(This article belongs to the Special Issue Novel Electrode Materials for Rechargeable Batteries, 2nd Edition)

► Show Figures

Graphical abstract

16 pages, 2468 KiB

Open AccessArticle

Optimization of Enzymolysis Modification Conditions of Dietary Fiber from Bayberry Pomace and Its Structural Characteristics and Physicochemical and Functional Properties

by Zhaolin Zhang, Qin Ruan, Xiaoming Sun and Jianfeng Yuan

Molecules 2024, 29(14), 3415; https://doi.org/10.3390/molecules29143415 - 21 Jul 2024

Cited by 1 | Viewed by 880

Abstract

Bayberry pomace, a nutrient-rich material abundant in dietary fiber (DF), has historically been underutilized due to a lack of thorough research. This study aimed to investigate the physicochemical and functional properties of the DF. Ultrasonic enzymatic treatment was performed to extract the total [...] Read more.

Bayberry pomace, a nutrient-rich material abundant in dietary fiber (DF), has historically been underutilized due to a lack of thorough research. This study aimed to investigate the physicochemical and functional properties of the DF. Ultrasonic enzymatic treatment was performed to extract the total DF, which was then optimized to produce modified soluble dietary fiber (MSDF) and insoluble dietary fiber (MIDF). The optimized conditions yielded 15.14% of MSDF with a water-holding capacity (WHC) of 54.13 g/g. The DFs were evaluated for their structural, physicochemical, and functional properties. The MSDF showed a higher (p < 0.05) WHC, oil-holding capacity (OHC), swelling capacity (SC), cation exchange capacity (CEC), and glucose adsorption capacity (GAC) (about 14.15, 0.88, 1.23, 1.22, and 0.34 times) compared to the DF. Additionally, the MSDF showed strong, superior radical scavenging and blood sugar-lowering capabilities, with a more porous surface morphology. A Fourier-transform infrared (FT-IR) spectroscopy analysis indicated that enzymatic modification degraded the cellulose and hemicellulose, reducing the DF crystallinity. Overall, the results demonstrated that cellulase hydrolysis could effectively improve the physicochemical and functional properties of DF, thereby paving the way for its development into functional food products. Full article

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

► Show Figures

Figure 1

12 pages, 1270 KiB

Open AccessArticle

Enhancing Bioactivity through the Transfer of the 2-(Hydroxymethoxy)Vinyl Moiety: Application in the Modification of Tyrosol and Hinokitiol

by Marcin Molski

Molecules 2024, 29(14), 3414; https://doi.org/10.3390/molecules29143414 - 21 Jul 2024

Viewed by 779

Abstract

Utilizing Density Functional Theory (DFT) calculations at the B3LYP/QZVP level and incorporating the Conductor-like Polarizable Continuum Model (C-PCM) for solvation, the thermodynamic and chemical activity properties of 21-(hydroxymethoxy)henicosadecaenal, identified in cultured freshwater pearls from the mollusk Hyriopsis cumingii, have been elucidated. The [...] Read more.

Utilizing Density Functional Theory (DFT) calculations at the B3LYP/QZVP level and incorporating the Conductor-like Polarizable Continuum Model (C-PCM) for solvation, the thermodynamic and chemical activity properties of 21-(hydroxymethoxy)henicosadecaenal, identified in cultured freshwater pearls from the mollusk Hyriopsis cumingii, have been elucidated. The study demonstrates that this compound releases formaldehyde, a potent antimicrobial agent, through dehydrogenation and deprotonation processes in both hydrophilic and lipophilic environments. Moreover, this polyenal exhibits strong anti-reductant properties, effectively scavenging free radicals. These critical properties classify the pearl-derived ingredient as a natural multi-functional compound, serving as a coloring, antiradical, and antimicrobial agent. The 2-(hydroxymethoxy)vinyl (HMV) moiety responsible for the formaldehyde release can be transferred to other compounds, thereby enhancing their biological activity. For instance, tyrosol (4-(2-hydroxyethyl)phenol) can be modified by substituting the less active 2-hydroxyethyl group with the active HMV one, and hinokitiol (4-isopropylotropolone) can be functionalized by attaching this moiety to the tropolone ring. A new type of meso-carrier, structurally modeled on pearls, with active substances loaded both in the layers and the mineral part, has been proposed. Full article

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

► Show Figures

Figure 1

24 pages, 746 KiB

Open AccessReview

Ion Chromatography and Related Techniques in Carbohydrate Analysis: A Review

by Rajmund Michalski and Joanna Kończyk

Molecules 2024, 29(14), 3413; https://doi.org/10.3390/molecules29143413 - 20 Jul 2024

Viewed by 2341

Abstract

Ion chromatography and related techniques have been the most popular separation methods used in the determination of organic and inorganic anions and cations, predominantly in water and wastewater samples. Making progress in their development and introducing new stationary phases, methods of detection and [...] Read more.

Ion chromatography and related techniques have been the most popular separation methods used in the determination of organic and inorganic anions and cations, predominantly in water and wastewater samples. Making progress in their development and introducing new stationary phases, methods of detection and preparation of samples for analyses have given rise to the broadening of their analytical range. Nowadays, they are also used for substances that are not ionic by nature but can convert to such forms under certain conditions. These encompass, among others, carbohydrates, whose role and significance in humans’ lives and environment is invaluable. Their presence in the air is mostly due to the industrial burning of biomass for energy production purposes. In addition, the content of sugars in plants, fruits and vegetables, constituting the base of human diets, affects our health condition. Given that, there is not only a need for their determination by means of routine methods but also for searching for novel analytical solutions. Based on literature data from the past decade, this paper presents the possibilities and examples of applications regarding ion chromatography and related techniques for the determination of carbohydrates in environmental samples, biomass and plants constituting food or raw materials for food production. Attention has been paid to the virtues and limitations of the discussed separation methods in this respect. Moreover, perspectives on their development have been defined. Full article

(This article belongs to the Special Issue A New Perspective on the Determination and Removal of Pollutants in the Environment)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Molecules, Volume 29, Issue 14 (July-2 2024) – 200 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI