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18 pages, 3815 KiB

Open AccessArticle

Sea Urchin-like NiCo₂O₄ Catalyst Activated Peroxymonosulfate for Degradation of Phenol: Performance and Mechanism

by Chunguang Chen, Junkai Zhang, Jia Liu, Jiani Li, Shuo Ma and Aishui Yu

Molecules 2024, 29(1), 152; https://doi.org/10.3390/molecules29010152 - 26 Dec 2023

Cited by 1 | Viewed by 2070

Abstract

How to efficiently activate peroxymonosulfate (PMS) in a complex water matrix to degrade organic pollutants still needs greater efforts, and cobalt-based bimetallic nanomaterials are desirable catalysts. In this paper, sea urchin-like NiCo₂O₄ nanomaterials were successfully prepared and comprehensively characterized for [...] Read more.

How to efficiently activate peroxymonosulfate (PMS) in a complex water matrix to degrade organic pollutants still needs greater efforts, and cobalt-based bimetallic nanomaterials are desirable catalysts. In this paper, sea urchin-like NiCo₂O₄ nanomaterials were successfully prepared and comprehensively characterized for their structural, morphological and chemical properties via techniques, such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), among others. The sea urchin-like NiCo₂O₄ nanomaterials exhibited remarkable catalytic performance in activating PMS to degrade phenol. Within the NiCo₂O₄/PMS system, the removal rate of phenol (50 mg L⁻¹, 250 mL) reached 100% after 45 min, with a reaction rate constant k of 0.091 min⁻¹, which was 1.4-times higher than that of the monometallic compound Co₃O₄/PMS system. The outstanding catalytic activity of sea urchin-like NiCo₂O₄ primarily arises from the synergistic effect between Ni and Co ions. Additionally, a comprehensive analysis of key parameters influencing the catalytic activity of the sea urchin-like NiCo₂O₄/PMS system, including reaction temperature, initial pH of solution, initial concentration, catalyst and PMS dosages and coexisting anions (HCO₃⁻, Cl⁻, NO₃⁻ and humic acid), was conducted. Cycling experiments show that the material has good chemical stability. Electron paramagnetic resonance (EPR) and quenching experiments verified that both radical activation (SO₄^•−, ^•OH, O₂^•−) and nonradical activation (¹O₂) are present in the NiCo₂O₄/PMS system. Finally, the possible degradation pathways in the NiCo₂O₄/PMS system were proposed based on gas chromatography–mass spectrometry (GC-MS). Favorably, sea urchin-like NiCo₂O₄-activated PMS is a promising technology for environmental treatment and the remediation of phenol-induced water pollution problems. Full article

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

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13 pages, 3969 KiB

Open AccessArticle

The Conformational Change of the L3 Loop Affects the Structural Changes in the Substrate Binding Pocket Entrance of β-Glucosidase

by Ki Hyun Nam

Molecules 2023, 28(23), 7807; https://doi.org/10.3390/molecules28237807 - 27 Nov 2023

Cited by 4 | Viewed by 1126

Abstract

β-glucosidase (Bgl) hydrolyzes cellobiose to glucose, thereby releasing non-reducing terminal glucosyl residues. Bgl is an essential enzyme belonging to the biomass-degrading enzyme family, which plays a vital role in enzymatic saccharification during biofuel production. The four loops above the Bgl substrate-binding pocket undergo [...] Read more.

β-glucosidase (Bgl) hydrolyzes cellobiose to glucose, thereby releasing non-reducing terminal glucosyl residues. Bgl is an essential enzyme belonging to the biomass-degrading enzyme family, which plays a vital role in enzymatic saccharification during biofuel production. The four loops above the Bgl substrate-binding pocket undergo a conformational change upon substrate recognition. However, the structural dynamism of this loop and how it is conserved among Bgl family members remain unknown. Herein, to better understand the four loops above the substrate-binding pocket of Bgl, four Bgl crystal structures in Thermoanaerobacterium saccharolyticum (TsaBgl) were determined at 1.5–2.1 Å. The L1, L2, and L4 loops of TsaBgl showed a rigid conformation stabilized by their neighboring residues via hydrogen bonds and hydrophobic interactions. The TsaBgl L3 loop showed relatively high flexibility and two different N-terminal region conformations. The conformational change in the TsaBgl L3 loop induced a change in charge and shaped at the substrate-binding pocket entrance. The amino acid sequences and structures of the TsaBgl L1–4 loops were compared with other 45 Bgl proteins, and a diversity of the L2 and L3 loops was observed. Differences in amino acids and lengths of Bgls L2–L3 loop induced differences in the conformation and structure of the Bgls substrate-binding pocket entrance. These findings expand our knowledge on the molecular function of the loops in the Bgl enzyme family. Full article

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

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14 pages, 2849 KiB

Open AccessArticle

In Situ Formation of a Relatively Transparent Ion-Associate Liquid Phase from an Aqueous Phase and Its Application to Microextraction/High-Performance Liquid Chromatography–Fluorescence Detection of Bisphenol A in Water

by Noriko Hata, Seira Takahashi, Sachiko Osada, Sakura Katagiri, Mayumi Naruse, Akane Igarashi, Kazuto Sazawa, Shigeru Taguchi and Hideki Kuramitz

Molecules 2023, 28(22), 7525; https://doi.org/10.3390/molecules28227525 - 10 Nov 2023

Cited by 3 | Viewed by 1231

Abstract

The design of a simple approach enabling the detection of bisphenol A (BPA) in water samples without the need for large amounts of solvents is of utmost importance. This paper reports a simple method for the separation, concentration, and quantification of BPA in [...] Read more.

The design of a simple approach enabling the detection of bisphenol A (BPA) in water samples without the need for large amounts of solvents is of utmost importance. This paper reports a simple method for the separation, concentration, and quantification of BPA in water samples using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) after its microextraction into an in situ formed organic ion-associate (IA) liquid phase (LP). Novel IA phase components without conjugated double bonds, such as benzene rings, were investigated. Ethylhexyloxypropylamine hydrochloride and sodium dodecyl sulfate solutions were added to the water samples to form IAs. The aqueous phase and ion-associate liquid phase (IALP) were separated by centrifugation. The aqueous phase was removed, and the liquid phase was recovered and measured using HPLC-FLD or HPLC-electrochemical detection (ECD). The concentrated phase (IALP) had a relatively low viscosity and could be injected directly into the chromatograph without dissolving it in organic solvents. The detection limits for BPA by HPLC-FLD and HPLC-ECD were 0.009 and 0.3 µg L⁻¹, respectively. Full article

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

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13 pages, 3734 KiB

Open AccessArticle

Synthesis of Low-Cost and High-Performance Dual-Atom Doped Carbon-Based Materials with a Simple Green Route as Anodes for Sodium-Ion Batteries

by Bin Lu, Chi Zhang, Ding-Rong Deng, Jian-Chun Weng, Jia-Xi Song, Xiao-Hong Fan, Gui-Fang Li, Yi Li and Qi-Hui Wu

Molecules 2023, 28(21), 7314; https://doi.org/10.3390/molecules28217314 - 28 Oct 2023

Cited by 5 | Viewed by 1531

Abstract

Sodium-ion batteries (SIBs) are promising alternatives to replace lithium-ion batteries as future energy storage batteries because of their abundant sodium resources, low cost, and high charging efficiency. In order to match the high energy capacity and density, designing an atomically doped carbonous material [...] Read more.

Sodium-ion batteries (SIBs) are promising alternatives to replace lithium-ion batteries as future energy storage batteries because of their abundant sodium resources, low cost, and high charging efficiency. In order to match the high energy capacity and density, designing an atomically doped carbonous material as the anode is presently one of the important strategies to commercialize SIBs. In this work, we report the preparation of high-performance dual-atom-doped carbon (C) materials using low-cost corn starch and thiourea (CH₄N₂S) as the precursors. The electronegativity and radii of the doped atoms and C are different, which can vary the embedding properties of sodium ions (Na⁺) into/on C. As sulfur (S) can effectively expand the layer spacing, it provides more channels for embedding and de-embedding Na⁺. The synergistic effect of N and S co-doping can remarkably boost the performance of SIBs. The capacity is preserved at 400 mAh g ⁻¹ after 200 cycles at 500 mA g⁻¹; more notably, the initial Coulombic efficiency is 81%. Even at a high rate of high current of 10 A g⁻¹, the cell capacity can still reach 170 mAh g⁻¹. More importantly, after 3000 cycles at 1 A g⁻¹, the capacity decay is less than 0.003% per cycle, which demonstrates its excellent electrochemical performance. These results indicate that high-performance carbon materials can be prepared using low-cost corn starch and thiourea. Full article

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

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18 pages, 6055 KiB

Open AccessArticle

Combination NIPS/TIPS Synthesis of α-Fe₂O₃ and α/γ-Fe₂O₃ Doped PVDF Composite for Efficient Piezocatalytic Degradation of Rhodamine B

by Asiyat G. Magomedova, Alina A. Rabadanova, Abdulatip O. Shuaibov, Daud A. Selimov, Dinara S. Sobola, Kamil Sh. Rabadanov, Kamal M. Giraev and Farid F. Orudzhev

Molecules 2023, 28(19), 6932; https://doi.org/10.3390/molecules28196932 - 4 Oct 2023

Cited by 6 | Viewed by 1717

Abstract

Highly porous membranes based on polyvinylidene fluoride (PVDF) with the addition of nanoscale particles of non-magnetic and magnetic iron oxides were synthesized using a combined method of non-solvent induced phase separation (NIPS) and thermo-induced phase separation (TIPS) based on the technique developed by [...] Read more.

Highly porous membranes based on polyvinylidene fluoride (PVDF) with the addition of nanoscale particles of non-magnetic and magnetic iron oxides were synthesized using a combined method of non-solvent induced phase separation (NIPS) and thermo-induced phase separation (TIPS) based on the technique developed by Dr. Blade. The obtained membranes were characterized using SEM, EDS, XRD, IR, diffuse reflectance spectroscopy, and fluorescent microscopy. It was shown that the membranes possessed a high fraction of electroactive phase, which increased up to a maximum of 96% with the addition of 2 wt% of α-Fe₂O₃ and α/γ-Fe₂O₃ nanoparticles. It was demonstrated that doping PVDF with nanoparticles contributed to the reduction of pore size in the membrane. All membranes exhibited piezocatalytic activity in the degradation of Rhodamine B. The degree of degradation increased from 69% when using pure PVDF membrane to 90% when using the composite membrane. The nature of the additive did not affect the piezocatalytic activity. It was determined that the main reactive species responsible for the degradation of Rhodamine B were ^•OH and ^•O₂⁻. It was also shown that under piezocatalytic conditions, composite membranes generated a piezopotential of approximately 2.5 V. Full article

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

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19 pages, 3755 KiB

Open AccessArticle

Photodynamic Treatment of Human Breast and Prostate Cancer Cells Using Rose Bengal-Encapsulated Nanoparticles

by Mir Muhammad Nasir Uddin, Alina Bekmukhametova, Anu Antony, Shital K. Barman, Jessica Houang, Ming J. Wu, James Hook, Laurel George, Richard Wuhrer, Damia Mawad, Daniel Ta and Antonio Lauto

Molecules 2023, 28(19), 6901; https://doi.org/10.3390/molecules28196901 - 1 Oct 2023

Cited by 2 | Viewed by 2590

Abstract

Cancer, a prominent cause of death, presents treatment challenges, including high dosage requirements, drug resistance, poor tumour penetration and systemic toxicity in traditional chemotherapy. Photodynamic therapy, using photosensitizers like rose bengal (RB) with a green laser, shows promise against breast cancer cells in [...] Read more.

Cancer, a prominent cause of death, presents treatment challenges, including high dosage requirements, drug resistance, poor tumour penetration and systemic toxicity in traditional chemotherapy. Photodynamic therapy, using photosensitizers like rose bengal (RB) with a green laser, shows promise against breast cancer cells in vitro. However, the hydrophilic RB struggles to efficiently penetrate the tumour site due to the unique clinical microenvironment, aggregating around rather than entering cancer cells. In this study, we have synthesized and characterized RB-encapsulated chitosan nanoparticles with a peak particle size of ~200 nm. These nanoparticles are readily internalized by cells and, in combination with a green laser (λ = 532 nm) killed 94–98% of cultured human breast cancer cells (MCF-7) and prostate cancer cells (PC3) at a low dosage (25 μg/mL RB-nanoparticles, fluence ~126 J/cm², and irradiance ~0.21 W/cm²). Furthermore, these nanoparticles are not toxic to cultured human normal breast cells (MCF10A), which opens an avenue for translational applications. Full article

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

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15 pages, 2675 KiB

Open AccessArticle

Effect of the Addition of Graphene Flakes on the Physical and Biological Properties of Composite Paints

by Natalia Bartczak, Jerzy Kowalczyk, Robert Tomala, Mariusz Stefanski, Damian Szymański, Maciej Ptak, Wiesław Stręk, Konrad Szustakiewicz, Tomasz Kurzynowski, Łukasz Szczepański, Adam Junka, Damian Gorczyca and Paweł Głuchowski

Molecules 2023, 28(16), 6173; https://doi.org/10.3390/molecules28166173 - 21 Aug 2023

Cited by 1 | Viewed by 1810

Abstract

In this study, graphene flakes were obtained using an electrolytic method and characterized using X-ray diffraction (XRD), Raman and FTIR spectroscopy, scanning and transmission electron microscopy (SEM/TEM). Graphene-based composites with varying concentrations of 0.5%, 1% and 3% by weight were prepared with acrylic [...] Read more.

In this study, graphene flakes were obtained using an electrolytic method and characterized using X-ray diffraction (XRD), Raman and FTIR spectroscopy, scanning and transmission electron microscopy (SEM/TEM). Graphene-based composites with varying concentrations of 0.5%, 1% and 3% by weight were prepared with acrylic paint, enamel and varnish matrices. The mechanical properties were evaluated using micro-hardness testing, while wettability and antimicrobial activity against three pathogens (Staphylococcus aureus 33591, Pseudomonas aeruginosa 15442, Candida albicans 10231) were also examined. The results indicate that the addition of graphene flakes significantly enhances both the mechanical and antimicrobial properties of the coatings. Full article

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

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14 pages, 4236 KiB

Open AccessArticle

New Janus Tricyclic Laddersiloxanes: Synthesis, Characterization, and Reactivity

by Yujia Liu, Midori Tokuda, Nobuhiro Takeda, Armelle Ouali and Masafumi Unno

Molecules 2023, 28(15), 5699; https://doi.org/10.3390/molecules28155699 - 27 Jul 2023

Viewed by 1291

Abstract

The synthesis of four novel syn-type tricyclic laddersiloxanes bearing eight or six alkenyl groups is presented. These compounds possess reactive alkenyl groups on both the bridged and side silicon atoms, and their structures were determined through characterization using multinuclear 1D and 2D [...] Read more.

The synthesis of four novel syn-type tricyclic laddersiloxanes bearing eight or six alkenyl groups is presented. These compounds possess reactive alkenyl groups on both the bridged and side silicon atoms, and their structures were determined through characterization using multinuclear 1D and 2D NMR spectroscopy, mass spectrometry, and elemental analysis techniques. To investigate their reactivity, the compounds were subjected to hydrosilylation using two different silanes, and the resulting fully hydrosilylated compounds were thoroughly analyzed. Remarkably, all the synthesized laddersiloxanes displayed high thermal stability, suggesting their potential as promising precursors for the development of new hybrid materials. Additionally, preliminary findings indicate the possibility of exploiting the reactivity difference between the alkenyl groups attached to the D- and T-unit silicon atoms for the synthesis of Janus molecules. These findings highlight the potential of the reported compounds as valuable building blocks in the construction of innovative materials. Full article

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

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13 pages, 11353 KiB

Open AccessArticle

Biomass Derived N-Doped Porous Carbon Made from Reed Straw for an Enhanced Supercapacitor

by Yuyi Liao, Zhongtao Shang, Guangrui Ju, Dingke Wang, Qiao Yang, Yuan Wang and Shaojun Yuan

Molecules 2023, 28(12), 4633; https://doi.org/10.3390/molecules28124633 - 8 Jun 2023

Cited by 20 | Viewed by 2052

Abstract

Developing advanced carbon materials by utilizing biomass waste has attracted much attention. However, porous carbon electrodes based on the electronic-double-layer-capacitor (EDLC) charge storage mechanism generally presents unsatisfactory capacitance and energy density. Herein, an N-doped carbon material (RSM-0.33-550) was prepared by directly pyrolyzing reed [...] Read more.

Developing advanced carbon materials by utilizing biomass waste has attracted much attention. However, porous carbon electrodes based on the electronic-double-layer-capacitor (EDLC) charge storage mechanism generally presents unsatisfactory capacitance and energy density. Herein, an N-doped carbon material (RSM-0.33-550) was prepared by directly pyrolyzing reed straw and melamine. The micro- and meso-porous structure and the rich active nitrogen functional group offered more ion transfer and faradaic capacitance. X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) measurements were used to characterize the biomass-derived carbon materials. The prepared RSM-0.33-550 possessed an N content of 6.02% and a specific surface area of 547.1 m² g⁻¹. Compared with the RSM-0-550 without melamine addition, the RSM-0.33-550 possessed a higher content of active nitrogen (pyridinic-N) in the carbon network, thus presenting an increased number of active sites for charge storage. As the anode for supercapacitors (SCs) in 6 M KOH, RSM-0.33-550 exhibited a capacitance of 202.8 F g⁻¹ at a current density of 1 A g⁻¹. At a higher current density of 20 A g⁻¹, it still retained a capacitance of 158 F g⁻¹. Notably, it delivered excellent stability with capacity retention of 96.3% at 20 A g⁻¹ after 5000 cycles. This work not only offers a new electrode material for SCs, but also gives a new insight into rationally utilizing biomass waste for energy storage. Full article

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

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25 pages, 7510 KiB

Open AccessArticle

Novel Route to Cationic Palladium(II)–Cyclopentadienyl Complexes Containing Phosphine Ligands and Their Catalytic Activities

by Dmitry S. Suslov, Mikhail V. Bykov, Marina V. Pakhomova, Timur S. Orlov, Zorikto D. Abramov, Anastasia V. Suchkova, Igor A. Ushakov, Pavel A. Abramov and Alexander S. Novikov

Molecules 2023, 28(10), 4141; https://doi.org/10.3390/molecules28104141 - 17 May 2023

Cited by 3 | Viewed by 1958

Abstract

The Pd(II) complexes [Pd(Cp)(L)_n]_m[BF₄]_m were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF₃∙OEt₂ (n = 2, m = 1: L = PPh₃ (1 [...] Read more.

The Pd(II) complexes [Pd(Cp)(L)_n]_m[BF₄]_m were synthesized via the reaction of cationic acetylacetonate complexes with cyclopentadiene in the presence of BF₃∙OEt₂ (n = 2, m = 1: L = PPh₃ (1), P(p-Tol)₃, tris(ortho-methoxyphenyl)phosphine (TOMPP), tri-2-furylphosphine, tri-2-thienylphosphine; n = 1, m = 1: L = dppf, dppp (2), dppb (3), 1,5-bis(diphenylphosphino)pentane; n = 1, m = 2 or 3: 1,6-bis(diphenylphosphino)hexane). Complexes 1–3 were characterized using X-ray diffractometry. The inspection of the crystal structures of the complexes enabled the recognition of (Cp^–)⋯(Ph-group) and (Cp^–)⋯(CH₂-group) interactions, which are of C–H…π nature. The presence of these interactions was confirmed theoretically via DFT calculations using QTAIM analysis. The intermolecular interactions in the X-ray structures are non-covalent in origin with an estimated energy of 0.3–1.6 kcal/mol. The cationic palladium catalyst precursors with monophosphines were found to be active catalysts for the telomerization of 1,3-butadiene with methanol (TON up to 2.4∙10⁴ mol 1,3-butadiene per mol Pd with chemoselectivity of 82%). Complex [Pd(Cp)(TOMPP)₂]BF₄ was found to be an efficient catalyst for the polymerization of phenylacetylene (PA) (catalyst activities up to 8.9 × 10³ g_PA·(mol_Pd·h)⁻¹ were observed) Full article

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

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15 pages, 3696 KiB

Open AccessArticle

Microstructure, Physical and Biological Properties, and BSA Binding Investigation of Electrospun Nanofibers Made of Poly(AA-co-ACMO) Copolymer and Polyurethane

by Hanaa Mansour, Samia M. Elsigeny, Fawzia I. Elshami, Mohamed Auf, Shaban Y. Shaban and Rudi van Eldik

Molecules 2023, 28(9), 3951; https://doi.org/10.3390/molecules28093951 - 8 May 2023

Cited by 4 | Viewed by 1680

Abstract

In this study, poly(AA-co-ACMO) and polyurethane-based nanofibers were prepared in a ratio of 1:1 (NF11) and 2:1 (NF21) as antimicrobial carriers for chronic wound management. Different techniques were used to characterize the nanofibers, and poly(AA-co-ACMO) was mostly found on the surface of PU. [...] Read more.

In this study, poly(AA-co-ACMO) and polyurethane-based nanofibers were prepared in a ratio of 1:1 (NF11) and 2:1 (NF21) as antimicrobial carriers for chronic wound management. Different techniques were used to characterize the nanofibers, and poly(AA-co-ACMO) was mostly found on the surface of PU. With an increase in poly(AA-co-ACMO) dose from 0 (PU) and 1:1 (NF11) to 2:1 (NF21) in the casting solution, the contact angle (CA) was reduced from 137 and 95 to 24, respectively, and hydrophilicity was significantly increased. As most medications inhibit biological processes by binding to a specific protein, in vitro protein binding was investigated mechanistically using a stopped-flow technique. Both NF11 and NF21 bind to BSA via two reversible steps: a fast second-order binding followed by a slow first-order one. The overall parameters for NF11 (K_a = 1.1 × 10⁴ M⁻¹, K_d = 89.0 × 10⁻⁶, ΔG⁰ = −23.1 kJ mol⁻¹) and NF21 (K_a = 189.0 × 10⁴ M⁻¹, K_d = 5.3 × 10⁻⁶ M, ΔG⁰ = −27.5 kJ mol⁻¹) were determined and showed that the affinity for BSA is approximately (NF11)/(NF21) = 1/180. This indicates that NF21 has much higher BSA affinity than NF11, although BSA interacts with NF11 much faster. NF21 with higher hydrophilicity showed effective antibacterial properties compared to NF11, in agreement with kinetic data. The study provided an approach to manage chronic wounds and treating protein-containing wastewater. Full article

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

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18 pages, 2692 KiB

Open AccessArticle

Ethanol Coupling Reactions over MgO–Al₂O₃ Mixed Oxide-Based Catalysts for Producing Biofuel Additives

by Anna Vikár, Ferenc Lónyi, Amosi Makoye, Tibor Nagy, Gyula Novodárszki, Róbert Barthos, Blanka Szabó, József Valyon, Magdolna R. Mihályi, Dhanapati Deka and Hanna E. Solt

Molecules 2023, 28(9), 3788; https://doi.org/10.3390/molecules28093788 - 28 Apr 2023

Cited by 2 | Viewed by 2054

Abstract

Catalytic conversion of ethanol to 1-butanol was studied over MgO–Al₂O₃ mixed oxide-based catalysts. Relationships between acid-base and catalytic properties and the effect of active metal on the hydrogen transfer reaction steps were investigated. The acid-base properties were studied by temperature-programmed [...] Read more.

Catalytic conversion of ethanol to 1-butanol was studied over MgO–Al₂O₃ mixed oxide-based catalysts. Relationships between acid-base and catalytic properties and the effect of active metal on the hydrogen transfer reaction steps were investigated. The acid-base properties were studied by temperature-programmed desorption of CO₂ and NH₃ and by the FT-IR spectroscopic examination of adsorbed pyridine. Dispersion of the metal promoter (Pd, Pt, Ru, Ni) was determined by CO pulse chemisorption. The ethanol coupling reaction was studied using a flow-through microreactor system, He or H₂ carrier gas, WHSV = 1

g_{E t O H} \cdot g_{c a t .}^{- 1} \cdot h^{- 1}

, at 21 bar, and 200–350 °C. Formation and transformation of surface species under catalytic conditions were studied by DRIFT spectroscopy. The highest butanol selectivity and yield was observed when the MgO–Al₂O₃ catalyst contained a relatively high amount of strong-base and medium-strong Lewis acid sites. The presence of metal improved the activity both in He and H₂; however, the butanol selectivity significantly decreased at temperatures ≥ 300 °C due to acceleration of undesired side reactions. DRIFT spectroscopic results showed that the active metal promoted H-transfer from H₂ over the narrow temperature range of 200–250 °C, where the equilibrium allowed significant concentrations of both dehydrogenated and hydrogenated products. Full article

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

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13 pages, 3344 KiB

Open AccessArticle

Donor-π-Acceptor-Type Fluorinated Tolane Containing a Semifluoroalkoxy Chain as a Condensed-Phase Luminophore

by Shigeyuki Yamada, Keigo Yoshida, Mitsuki Kataoka, Mitsuo Hara and Tsutomu Konno

Molecules 2023, 28(6), 2764; https://doi.org/10.3390/molecules28062764 - 19 Mar 2023

Cited by 4 | Viewed by 1783

Abstract

Photoluminescent liquid-crystalline (PLLC) molecules, which can easily tune the PL behavior through the crystal (Cry)–LC phase transition, have attracted significant attention. Previously, we have demonstrated that the incorporation of a semifluoroalkoxy chain into π-conjugated mesogen is a promising approach for developing PLLC molecules [...] Read more.

Photoluminescent liquid-crystalline (PLLC) molecules, which can easily tune the PL behavior through the crystal (Cry)–LC phase transition, have attracted significant attention. Previously, we have demonstrated that the incorporation of a semifluoroalkoxy chain into π-conjugated mesogen is a promising approach for developing PLLC molecules with PL and SmA LC characteristics. We focused on the LC and PL characteristics of the molecules induced by the semifluoroalkoxy chain and fluorinated tolanes in the condensed phase. In this study, we developed cyano- or ethoxycarbonyl-terminated donor-π-acceptor-type fluorinated tolanes containing a semifluoroalkoxy flexible chain. The cyano-terminated fluorinated tolanes exhibited intense light-blue photoluminescence in the crystalline phase and did not exhibit any LC phase. In contrast, blue photoluminescence in the ethoxycarbonyl-terminated analogs was slightly weak; however, they exhibited Cry–SmA phase transition during the heating and cooling processes. The PL intensity of the ethoxycarbonyl-terminated fluorinated tolanes significantly decreased in the SmA phase; however, their PL colors changed during the Cry–SmA phase transition. This indicates that the developed tolanes are promising temperature-dependent PL materials, such as PL thermosensors or PL thermometers. Full article

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

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Review

Jump to: Research

18 pages, 31421 KiB

Open AccessReview

Preventing the Galvanic Replacement Reaction toward Unconventional Bimetallic Core–Shell Nanostructures

by Kai Liu, Zhun Qiao and Chuanbo Gao

Molecules 2023, 28(15), 5720; https://doi.org/10.3390/molecules28155720 - 28 Jul 2023

Cited by 1 | Viewed by 2061

Abstract

A bimetallic core–shell nanostructure is a versatile platform for achieving intriguing optical and catalytic properties. For a long time, this core–shell nanostructure has been limited to ones with noble metal cores. Otherwise, a galvanic replacement reaction easily occurs, leading to hollow nanostructures or [...] Read more.

A bimetallic core–shell nanostructure is a versatile platform for achieving intriguing optical and catalytic properties. For a long time, this core–shell nanostructure has been limited to ones with noble metal cores. Otherwise, a galvanic replacement reaction easily occurs, leading to hollow nanostructures or completely disintegrated ones. In the past few years, great efforts have been devoted to preventing the galvanic replacement reaction, thus creating an unconventional class of core–shell nanostructures, each containing a less-stable-metal core and a noble metal shell. These new nanostructures have been demonstrated to show unique optical and catalytic properties. In this work, we first briefly summarize the strategies for synthesizing this type of unconventional core–shell nanostructures, such as the delicately designed thermodynamic control and kinetic control methods. Then, we discuss the effects of the core–shell nanostructure on the stabilization of the core nanocrystals and the emerging optical and catalytic properties. The use of the nanostructure for creating hollow/porous nanostructures is also discussed. At the end of this review, we discuss the remaining challenges associated with this unique core–shell nanostructure and provide our perspectives on the future development of the field. Full article

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

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19 pages, 7033 KiB

Open AccessFeature PaperReview

Dry Water as a Promoter for Gas Hydrate Formation: A Review

by Yu Wei and Nobuo Maeda

Molecules 2023, 28(9), 3731; https://doi.org/10.3390/molecules28093731 - 26 Apr 2023

Cited by 11 | Viewed by 2881

Abstract

Applications of clathrate hydrate require fast formation kinetics of it, which is the long-standing technological bottleneck due to mass transfer and heat transfer limitations. Although several methods, such as surfactants and mechanical stirring, have been employed to accelerate gas hydrate formation, the problems [...] Read more.

Applications of clathrate hydrate require fast formation kinetics of it, which is the long-standing technological bottleneck due to mass transfer and heat transfer limitations. Although several methods, such as surfactants and mechanical stirring, have been employed to accelerate gas hydrate formation, the problems they bring are not negligible. Recently, a new water-in-air dispersion stabilized by hydrophobic nanosilica, dry water, has been used as an effective promoter for hydrate formation. In this review, we summarize the preparation procedure of dry water and factors affecting the physical properties of dry water dispersion. The effect of dry water dispersion on gas hydrate formation is discussed from the thermodynamic and kinetic points of view. Dry water dispersion shifts the gas hydrate phase boundary to milder conditions. Dry water increases the gas hydrate formation rate and improves gas storage capacity by enhancing water-guest gas contact. The performance comparison and synergy of dry water with other common hydrate promoters are also summarized. The self-preservation effect of dry water hydrate was investigated. Despite the prominent effect of dry water in promoting gas hydrate formation, its reusability problem still remains to be solved. We present and compare several methods to improve its reusability. Finally, we propose knowledge gaps in dry water hydrate research and future research directions. Full article

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

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