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16 pages, 1365 KiB  
Article
Generation of Formates Following 20 kHz Sonication of DSPE-mPEG2000 PEGylated Phospholipid Micelles
by Perouza Parsamian and Paul Pantano
Pharmaceutics 2025, 17(8), 1008; https://doi.org/10.3390/pharmaceutics17081008 - 1 Aug 2025
Viewed by 244
Abstract
Background: Previous research has demonstrated that 20 kHz probe or 37 kHz bath sonication of poloxamers comprising polypropylene glycol (PPG) and polyethylene glycol (PEG) blocks can generate degradation byproducts that are toxic to mammalian cells and organisms. Herein, an investigation of a [...] Read more.
Background: Previous research has demonstrated that 20 kHz probe or 37 kHz bath sonication of poloxamers comprising polypropylene glycol (PPG) and polyethylene glycol (PEG) blocks can generate degradation byproducts that are toxic to mammalian cells and organisms. Herein, an investigation of a PEGylated phospholipid micelle was undertaken to identify low-molecular-weight sonolytic degradation byproducts that could be cytotoxic. The concern here lies with the fact that sonication is a frequently employed step in drug delivery manufacturing processes, during which PEGylated phospholipids can be subjected to shear forces and other extreme oxidative and thermal conditions. Methods: Control and 20 kHz-sonicated micelles of DSPE-mPEG2000 were analyzed using dynamic light scattering (DLS) and zeta potential analyses to study colloidal properties, matrix-assisted laser desorption/ionization–time of flight (MALDI-TOF) mass spectroscopy (MS) and proton nuclear magnetic resonance (1H-NMR) spectroscopy to study the structural integrity of DSPE-mPEG2000, and 1H-NMR spectroscopy and high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection to quantitate the formation of low-molecular-weight degradation byproducts. Results: MALDI-TOF-MS analyses of 20 kHz-sonicated DSPE-mPEG2000 revealed the loss of ethylene glycol moieties in accordance with depolymerization of the PEG chain; 1H-NMR spectroscopy showed the presence of formate, a known oxidative/thermal degradation product of PEG; and HPLC-UV showed that the generation of formate was dependent on 20 kHz probe sonication time between 5 and 60 min. Conclusions: It was found that 20 kHz sonication can degrade the PEG chain of DSPE-mPEG2000, altering the micelle’s PEG corona and generating formate, a known ocular toxicant. Full article
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17 pages, 3206 KiB  
Article
Inverse Punicines: Isomers of Punicine and Their Application in LiAlO2, Melilite and CaSiO3 Separation
by Maximilian H. Fischer, Ali Zgheib, Iliass El Hraoui, Alena Schnickmann, Thomas Schirmer, Gunnar Jeschke and Andreas Schmidt
Separations 2025, 12(8), 202; https://doi.org/10.3390/separations12080202 - 30 Jul 2025
Viewed by 133
Abstract
The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. [...] Read more.
The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. These amphoteric molecules were synthesized via a straightforward four-step route and structurally tuned for hydrophobization by alkylation. Their performance as collectors was evaluated in microflotation experiments of lithium aluminate (LiAlO2) and silicate matrix minerals such as melilite and calcium silicate. Characterization techniques including ultraviolet-visible (UV-Vis), nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy as well as contact angle, zeta potential (ζ potential) and microflotation experiments revealed strong pH- and structure-dependent interactions with mineral surfaces. Notably, N-alkylated inverse Punicine derivatives showed high flotation yields for LiAlO2 at pH of 11, with a derivative possessing a dodecyl group attached to the nitrogen as collector achieving up to 86% recovery (collector conc. 0.06 mmol/L). Preliminary separation tests showed Li upgrading from 5.27% to 6.95%. Radical formation and light-response behavior were confirmed by ESR and flotation tests under different illumination conditions. These results demonstrate the potential of inverse Punicines as tunable, sustainable flotation reagents for advanced lithium recycling from complex slag systems. Full article
(This article belongs to the Special Issue Application of Green Flotation Technology in Mineral Processing)
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23 pages, 4192 KiB  
Article
Efficacy of Various Complexing Agents for Displacing Biologically Important Ligands from Eu(III) and Cm(III) Complexes in Artificial Body Fluids—An In Vitro Decorporation Study
by Sebastian Friedrich, Antoine Barberon, Ahmadabdurahman Shamoun, Björn Drobot, Katharina Müller, Thorsten Stumpf, Jerome Kretzschmar and Astrid Barkleit
Int. J. Mol. Sci. 2025, 26(15), 7112; https://doi.org/10.3390/ijms26157112 - 23 Jul 2025
Cited by 1 | Viewed by 328
Abstract
Incorporation of lanthanide (Ln) and actinide (An) ions into the human body poses significant chemotoxic and radiotoxic risks, necessitating effective decorporation strategies. This study investigates the displacement of biologically relevant ligands from trivalent ions of europium, Eu(III), and curium, Cm(III), in artificial biofluids [...] Read more.
Incorporation of lanthanide (Ln) and actinide (An) ions into the human body poses significant chemotoxic and radiotoxic risks, necessitating effective decorporation strategies. This study investigates the displacement of biologically relevant ligands from trivalent ions of europium, Eu(III), and curium, Cm(III), in artificial biofluids by various complexing agents, i.e., ethylenediaminetetraacetic acid (EDTA), ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), diethylenetriaminepentaacetic acid (DTPA), and spermine-based hydroxypyridonate chelator 3,4,3-LI(1,2-HOPO) (HOPO). Utilizing a modified unified bioaccessibility method (UBM) to simulate gastrointestinal conditions, we conducted concentration-dependent displacement experiments at both room and body temperatures. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) supported by 2H nuclear magnetic resonance (NMR) spectroscopy and thermodynamic modelling revealed the complexation efficacy of the agents under physiological conditions. Results demonstrate that high affinity, governed by complex stability constants and ligand pKa values, is critical to overcome cation and anion competition and leads to effective decorporation. Additionally, there is evidence that cyclic ligands are inferior to linear ligands for this application. HOPO and DTPA exhibited superior displacement efficacy, particularly in the complete gastrointestinal tract simulation. This study highlights the utility of in vitro workflows for evaluating decorporation agents and emphasizes the need for ligands with optimal binding characteristics for enhanced chelation therapies. Full article
(This article belongs to the Special Issue Toxicity of Heavy Metal Compounds)
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15 pages, 4059 KiB  
Article
Surface Fluorination for the Stabilization in Air of Garnet-Type Oxide Solid Electrolyte for Lithium Ion Battery
by Michael Herraiz, Saida Moumen, Kevin Lemoine, Laurent Jouffret, Katia Guérin, Elodie Petit, Nathalie Gaillard, Laure Bertry, Reka Toth, Thierry Le Mercier, Valérie Buissette and Marc Dubois
Batteries 2025, 11(7), 268; https://doi.org/10.3390/batteries11070268 - 16 Jul 2025
Viewed by 283
Abstract
After reviewing the state of the art of the fluorination of inorganic solid electrolytes, an application of gas/solid fluorination is given and how it can be processed. Garnet-type oxide has been chosen. These oxides with an ideal structure of chemical formula A3 [...] Read more.
After reviewing the state of the art of the fluorination of inorganic solid electrolytes, an application of gas/solid fluorination is given and how it can be processed. Garnet-type oxide has been chosen. These oxides with an ideal structure of chemical formula A3B2(XO4)3 are mainly known for their magnetic and dielectric properties. Certain garnets may have a high enough Li+ ionic conductivity to be used as solid electrolyte of lithium ion battery. The surface of LLZO may be changed in contact with the moisture and CO2 present in the atmosphere that results in a change of the conductivity at the interface of the solid. LiOH and/or lithium carbonate are formed at the surface of the garnet particles. In order to allow for handling and storage under normal conditions of this solid electrolyte, surface fluorination was performed using elemental fluorine. When controlled using mild conditions (temperature lower or equal to 200 °C, either in static or dynamic mode), the addition of fluorine atoms to LLZO with Li6,4Al0,2La3Zr2O12 composition is limited to the surface, forming a covering layer of lithium fluoride LiF. The effect of the fluorination was evidenced by IR, Raman, and NMR spectroscopies. If present in the pristine LLZO powder, then the carbonate groups disappear. More interestingly, contrary to the pristine LLZO, the contents of these groups are drastically reduced even after storage in air up to 45 days when the powder is covered with the LiF layer. Surface fluorination could be applied to other solid electrolytes that are air sensitive. Full article
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16 pages, 2441 KiB  
Article
Phosphonium Salt-Functionalized β-Cyclodextrin Film for Ultrasensitive and Selective Electrochemical Impedance Spectroscopy Detection of Perchlorate in Drinking Water
by Zeineb Baatout, Achref Jebnouni, Nawfel Sakly, Safa Teka, Nuzaiha Mohamed, Sayda Osman, Raoudha Soury, Mabrouka El Oudi, Salman Hamdan Alsaqri, Nejmeddine Smida Jaballah and Mustapha Majdoub
Polymers 2025, 17(14), 1937; https://doi.org/10.3390/polym17141937 - 15 Jul 2025
Viewed by 396
Abstract
This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO4) using electrochemical impedance spectroscopy (EIS). Structural confirmation via 1H [...] Read more.
This work represents the first use of a phosphonium salt-functionalized β-Cyclodextrin polymer (β-CDP) as a highly selective sensing membrane for monitoring the safety of drinking water against perchlorate ions (ClO4) using electrochemical impedance spectroscopy (EIS). Structural confirmation via 1H NMR, 13C NMR, 31P NMR, and FT-IR spectroscopies combined with AFM and contact angle measurements demonstrate how the enhanced solubility of modified cyclodextrin improves thin film quality. The innovation lies in the synergistic combination of two detection mechanisms: the “Host-Guest” inclusion in the cyclodextrin cavity and anionic exchange between the bromide ions of the phosphonium groups and perchlorate anions. Under optimized functionalization conditions, EIS reveals high sensitivity and selectivity, achieving a record-low detection limit (LOD) of ~10−12 M and a wide linear range of detection (10−11 M–10−4 M). Sensing mechanisms at the functionalized transducer interfaces are examined through numerical fitting of Cole-Cole impedance spectra via a single relaxation equivalent circuit. Real water sample analysis confirms the sensor’s practical applicability, with recoveries between 96.9% and 109.8% and RSDs of 2.4–4.8%. Finally, a comparative study with reported membrane sensors shows that β-CDP offers superior performance, wider range, higher sensitivity, lower LOD, and simpler synthesis. Full article
(This article belongs to the Special Issue Development of Polymer Materials as Functional Coatings)
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16 pages, 2858 KiB  
Article
Heterobimetallic Uranium(V)-Alkali Metal Alkoxides: Expanding the Chemistry of f-Block Elements
by Andreas Lichtenberg, Lidia Inderdühnen, Aida Lichtenberg and Sanjay Mathur
Molecules 2025, 30(11), 2361; https://doi.org/10.3390/molecules30112361 - 29 May 2025
Viewed by 536
Abstract
Heterobimetallic uranium(V) alkoxides incorporating monovalent alkali metal counterions display remarkable structural versatility, dictated by the steric demands of the alkoxide ligands and the ionic radius of the alkali metal. Compounds of the general formula [UM(OtBu)6] (UM-OtBu [...] Read more.
Heterobimetallic uranium(V) alkoxides incorporating monovalent alkali metal counterions display remarkable structural versatility, dictated by the steric demands of the alkoxide ligands and the ionic radius of the alkali metal. Compounds of the general formula [UM(OtBu)6] (UM-OtBu-type: M = Na, K, Rb, Cs) were obtained by: (i) reacting [U(OtBu)5(py)] with equimolar amounts of alkali metal silylamides in tert-butyl alcohol, and (ii) oxidative transformation of [UM2(OtBu)6] (M = Na, K, Rb, Cs) upon reaction with iodine. Trans-alcoholysis of uranium heterobimetallic tert-butoxides with sterically less demanding iso-propyl alcohol yields oligomeric or polymeric iso-propoxide derivatives of the general formula [UM(OiPr)6]n, where the nuclearity depends on the alkali metal (n = 2 for M = Li; n = ∞ for M = Na, K, Rb). The capacity of alkali metal ions to adopt flexible coordination geometries results in different structural types ranging from finite clusters to infinite chains, with [ULi(OiPr)6]2 (ULi-OiPr-1) found to be dimeric, whereas [UM(OiPr)6] (UM-OiPr-2-type, M = Na, K) and [URb(OiPr)6] (URb-OiPr-3) exhibit a polymeric architecture. These findings provide fresh insights into the structure-directing influence of alkali metals on actinide coordination chemistry and broaden the chemistry of actinide alkoxides. All compounds were unambiguously characterized in both solution and solid-state through NMR and IR spectroscopic studies, as well as single crystal X-ray diffraction analysis. Full article
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13 pages, 3428 KiB  
Article
Mechanochemical Defect Engineering of Nb2O5: Influence of LiBH4 and NaBH4 Reduction on Structure and Photocatalysis
by Anna Michaely, Elias C. J. Gießelmann and Guido Kickelbick
Solids 2025, 6(2), 26; https://doi.org/10.3390/solids6020026 - 26 May 2025
Viewed by 710
Abstract
Partial reduction of transition metal oxides via defect engineering is a promising strategy to enhance their electronic and photocatalytic properties. In this study, we systematically explored the mechanochemical reduction of Nb2O5 using LiBH4 and NaBH4 as reducing agents. [...] Read more.
Partial reduction of transition metal oxides via defect engineering is a promising strategy to enhance their electronic and photocatalytic properties. In this study, we systematically explored the mechanochemical reduction of Nb2O5 using LiBH4 and NaBH4 as reducing agents. Electron paramagnetic resonance (EPR) spectroscopy confirmed a successful partial reduction of the oxide, as seen by the presence of unpaired electrons. Interestingly, larger hydride concentrations did not necessarily enable a higher degree of reduction as large amounts of boron hydrides acted as a buffer material and thus hindered the effective transfer of mechanical energy. Powder X-ray diffraction (PXRD) and 7Li solid-state NMR spectroscopy indicated the intercalation of Li+ into the Nb2O5 lattice. Raman spectroscopy further revealed the increased structural disorder, while optical measurements showed a decreased band gap compared with pristine Nb2O5. The partially reduced samples showed significantly enhanced photocatalytic performance for methylene blue degradation relative to the unmodified oxides. Full article
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12 pages, 1760 KiB  
Article
Streamlined Postprocessing of NMR Structures with the Molecular Restrainer: A Universal Tool for High-Quality Protein–Ligand Models and Non-Standard Amino Acid Residues
by Jiří Mareš, Guneet Singh Tarang, Dmitriy Marin, Mehdi Mobli, Stephane Redon and Julien Orts
Int. J. Mol. Sci. 2025, 26(11), 5091; https://doi.org/10.3390/ijms26115091 - 26 May 2025
Viewed by 479
Abstract
We present a molecular restrainer tool capable of energy-minimizing NMR-derived structures using the universal force field (UFF) and NOE-derived distance restraints. The implementation is a part of SAMSON (version 2024 and newer), an integrative molecular design platform. The strength of our tool lies [...] Read more.
We present a molecular restrainer tool capable of energy-minimizing NMR-derived structures using the universal force field (UFF) and NOE-derived distance restraints. The implementation is a part of SAMSON (version 2024 and newer), an integrative molecular design platform. The strength of our tool lies in its ability to swiftly process any molecule and molecular complex without the need to create force field parameters and topology files. We show, using examples, that the quality of these refined structures is significantly improved compared to the starting structures derived by CYANA. Currently, the implementation is targeted toward the postprocessing of structures derived by the software CYANA but can easily be adapted to other molecular restraint formats. This tool enables the generation of publication-ready protein–ligand complex structures for PDB deposition, requiring minimal additional effort beyond the initial NMR structure calculation. Full article
(This article belongs to the Section Biochemistry)
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13 pages, 5998 KiB  
Article
The Microstructure, Crystallization Behavior, and Mechanical Performance Evolutions of Li2O-Al2O3-SiO2 Glass and Glass–Ceramics with Different Alkaline Earth Oxide Modifications
by Chi Zheng, Danni Li, Mengshuo Guo, Jihong Zhang, Jun Xie and Jianjun Han
Materials 2025, 18(6), 1383; https://doi.org/10.3390/ma18061383 - 20 Mar 2025
Viewed by 709
Abstract
The introduction of alkaline earth oxides into Li2O-Al2O3-SiO2 glass components can improve the mechanical and optical performances of glass and glass–ceramics for various applications. In this research, microstructures, thermal properties, crystallization behavior, and mechanical performance changes [...] Read more.
The introduction of alkaline earth oxides into Li2O-Al2O3-SiO2 glass components can improve the mechanical and optical performances of glass and glass–ceramics for various applications. In this research, microstructures, thermal properties, crystallization behavior, and mechanical performance changes in specific Li2O-Al2O3-SiO2 glass with the introduction of different alkali earth oxides, MgO, CaO, SrO, and BaO, were investigated. From Raman and NMR spectra microstructure analysis, it was confirmed that the addition of MgO could compete with Al as a network former and charge compensator, while increasing the bridging oxygen number with Si and affecting the chemical shift in 29Si. Meanwhile, the glass structures slightly changed due to the introduction of CaO, SrO, and BaO, with larger ionic radii. Meanwhile, the glass transition and first crystallization temperatures increased due to MgO introduction and then decreased with larger-radii alkali earth oxides’ addition, due to different glass network connectivity. After heat treatment, the crystal phases in the glass–ceramics changed with the introduction of alkaline earth oxides. The main crystal phases varied from Li2Si2O5, SiO2, and LiAlSi4O10 in glass without alkali earth oxide introduction; to SiO2, LixAlxSi3−xO6, and MgAl2Si4O12 in glass with MgO addition; to SiO2 and LixAlxSi3−xO6 with CaO addition; to SiO2, LiAlSi4O10, and Li2SiO3 for glass with SrO addition; and further to Li2SiO5, SiO2, and LiAlSi4O10 for glass with BaO addition. Moreover, in the mechanical performance of the glass–ceramics, the Vickers hardness and elastic modulus reached a maximum of 8.61 GPa for glass with MgO and 90.12 GPa for glass with BaO modification, respectively, probably due to different crystal phases. More importantly, the crack resistance values presented a large increase for MgO glass and MgO- or CaO-modified glass–ceramics. Full article
(This article belongs to the Section Advanced and Functional Ceramics and Glasses)
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13 pages, 3364 KiB  
Article
Synthesis of Amorphous Cellulose Derivatives via Michael Addition to Hydroxyalkyl Acrylates for Thermoplastic Film Applications
by Hiroyuki Nagaishi, Masayasu Totani and Jun-ichi Kadokawa
Polymers 2024, 16(22), 3142; https://doi.org/10.3390/polym16223142 - 11 Nov 2024
Cited by 2 | Viewed by 1471
Abstract
The aim of this study is to prepare new cellulose derivatives that show good feasibility and processability. Accordingly, in this study, we demonstrate Michael addition to hydroxyalkyl acrylates, that is, 2-hydroxyethyl and 4-hydroxybutyl acrylates (HEA and HBA, respectively), to synthesize amorphous cellulose derivatives [...] Read more.
The aim of this study is to prepare new cellulose derivatives that show good feasibility and processability. Accordingly, in this study, we demonstrate Michael addition to hydroxyalkyl acrylates, that is, 2-hydroxyethyl and 4-hydroxybutyl acrylates (HEA and HBA, respectively), to synthesize amorphous cellulose derivatives under alkaline conditions. The reactions were carried out in the presence of LiOH in ionic liquid (1-butyl-2,3-dimethylimidazolium chloride)/N,N-dimethylformamide (DMF) solvents at room temperature or 50 °C for 1 h. The Fourier transform infrared and 1H nuclear magnetic resonance (NMR) measurements of the products supported the progress of Michael addition; however, the degrees of substitution (DS) were not high (0.3–0.6 for HEA and 0.6 for HBA). The powder X-ray diffraction analysis of the products indicated their amorphous nature. The cellulosic Michael adduct from HEA with DS = 0.6 was swollen with high polar organic liquids, such as DMF. In addition to swelling with these liquids, the cellulosic Michael adduct from HBA was soluble in dimethyl sulfoxide (DMSO), leading to its 1H NMR analysis in DMSO-d6. This adduct was found to form a cast film with flexible properties from its DMSO solutions. Furthermore, films containing an ionic liquid, 1-butyl-3-methylimidazolium chloride, showed thermoplasticity. The Michael addition approach to hydroxyalkyl acrylates is quite effective to totally reduce crystallinity, leading to good feasibility and processability in cellulosic materials, even with low DS. In addition, the present thermoplastic films will be applied in practical, bio-based, and eco-friendly fields. Full article
(This article belongs to the Special Issue Polysaccharides: Synthesis, Properties and Applications)
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15 pages, 3547 KiB  
Article
Value-Added Products Derived from Poly(ethylene terephthalate) Glycolysis
by Simona Zahova, Pencho Tuleshkov, Kolio Troev and Violeta Mitova
Molecules 2024, 29(17), 4261; https://doi.org/10.3390/molecules29174261 - 8 Sep 2024
Viewed by 1881
Abstract
Among polymer wastes, poly(ethylene terephthalate) (PET) is the most important commercial thermoplastic polyester. Less than 30% of total PET production is recycled into new products. Therefore, large amounts of waste PET need to be recycled. We describe a feasible approach for the direct [...] Read more.
Among polymer wastes, poly(ethylene terephthalate) (PET) is the most important commercial thermoplastic polyester. Less than 30% of total PET production is recycled into new products. Therefore, large amounts of waste PET need to be recycled. We describe a feasible approach for the direct application of the glycolysis products of PET (GP-PET), without further purification, for the synthesis of value-added products. It was established that GP-PET is valorized via phosphorylation with phenylphosphonic dichloride (PPD), as well as with trimethyl phosphate (TMP). When PPD is used, a condensation reaction takes place with the evolution of hydrogen chloride. During the interaction between GP-PET and TMP, the following reactions take place simultaneously: a transesterification with the participation of the hydroxyl group of GP-PET and the methoxy group of TMP and an exchange reaction between the ester group of GP-PET and the methyl ester group of TMP. The occurrence of the exchange reaction was confirmed by 1H, 31P, 13C NMR, and GPC analysis. Thermogravimetric analysis (TGA) revealed that the percentage of a carbon residual (CR) implies the possibility of using the end products as flame retardant (FR) additives, especially for polyurethanes as well as thermal stabilizers of polymer materials or Li-ion cells. Full article
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18 pages, 2994 KiB  
Article
Intensive Cycloalkyl-Fused Pyridines for Aminopyridyl–Zinc–Heteroimidazoles Achieving High Efficiency toward the Ring-Opening Polymerization of Lactides
by Yun Wang, Wenjuan Zhang, Pengjiang Zhu, Wei You, Xiaopan Xue, Rui Wang, Yanping Ma and Wen-Hua Sun
Molecules 2024, 29(17), 4150; https://doi.org/10.3390/molecules29174150 - 31 Aug 2024
Viewed by 1535
Abstract
The model precatalyst sp3- and sp2-N dinitrogen-coordinated zinc–heteroimidazole has been used as an efficient catalyst for the ring-opening polymerization of cyclic esters. Subsequent to our exceptional active 5,6,7-trihydroquinolin-8-amine-zinc catalysts for the ring-opening polymerization (ROP) of ε-caprolactone, various pyridine-fused [...] Read more.
The model precatalyst sp3- and sp2-N dinitrogen-coordinated zinc–heteroimidazole has been used as an efficient catalyst for the ring-opening polymerization of cyclic esters. Subsequent to our exceptional active 5,6,7-trihydroquinolin-8-amine-zinc catalysts for the ring-opening polymerization (ROP) of ε-caprolactone, various pyridine-fused cycloalkanones (ring size from five to eight) are developed for the correspondent fused amine–pyridine derivatives and their zinc–heteroimidazole chloride complexes Zn1Zn8 (LZnCl2) bearing N-diphenylphosphinoethyl pendants. Activated with two equivalents of LiN(SiMe3)2, the title zinc complexes efficiently promote the ROP of L-lactide (L-LA) in situ; among them, Zn4/2Li(NSiMe3)2 catalyzed 500 equivalent L-LA at 80 °C with 92% conversion in 5 min (TOF: 5520 h−1). Under the same conditions, the catalytic efficiency for the ROP of rac-LA by Zn1Zn8/2Li(NSiMe3)2 was slightly lower than that for L-LA (highest TOF: 4440 h−1). In both cases, cyclooctyl-fused pyridyl–zinc complexes exhibited higher activity than others, while the cycloheptyl-fused zinc complexes showed the lowest activity. The microstructure analysis of the polymers showed they possessed a linear structure capped with CH3O as major and cyclic structure as minor. In this work, all the ligands and zinc complexes were well characterized by 1H/13C/31P NMR, FT-IR spectroscopy as well as elemental analysis. Full article
(This article belongs to the Special Issue Organometallic Compounds: Design, Synthesis and Application)
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8 pages, 1015 KiB  
Communication
Complex Formation of Ag+ and Li+ with Host Molecules Modeled on Intercalation of Graphite
by Yuriko Uetake and Hiroyuki Takemura
Molecules 2024, 29(17), 3987; https://doi.org/10.3390/molecules29173987 - 23 Aug 2024
Viewed by 955
Abstract
Pi-stacked and box-shaped host molecules with xanthene as the basis and pyrene as the π-plane were synthesized to verify cation–π interactions between graphene and metal cations. Since crystal structure analysis was not available, DFT calculations were performed to determine the optimized structure, and [...] Read more.
Pi-stacked and box-shaped host molecules with xanthene as the basis and pyrene as the π-plane were synthesized to verify cation–π interactions between graphene and metal cations. Since crystal structure analysis was not available, DFT calculations were performed to determine the optimized structure, and the π-planes were found to have a slipped parallel structure, with average distances of 456.2–581.0 pm for the stacked compound and 463.4–471.4 pm for the box-shaped compound. Li+ and Ag+ were chosen as acceptors for complexation with metal ions, and their interactions with the π-plane were clarified by NMR titration. Clearly, the interaction with metal ions increased when pyrene π-planes were stacked rather than the pyrene itself. In the stacked compound, the association constants of Ag+ and Li+ were similar; however, in the box-shaped host molecule, only Ag+ had moderate coordination ability, but the interaction with Li+ was very weak, comparable to the interaction with pyrene. As a result, intercalation is more likely to occur in stacked host compound 1, which has some degree of freedom in the pyrene rings, than in the box-shaped compound. Full article
(This article belongs to the Special Issue Two-Dimensional Materials: From Synthesis to Applications)
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12 pages, 4198 KiB  
Article
Sodium Filling in Superadamantoide Na1.36(Si0.86Ga0.14)2As2.98 and the Mixed Valent Arsenidosilicate-Silicide Li1.5Ga0.9Si3.1As4
by Marlo Schöneich, Lucas G. Balzat, Bettina V. Lotsch and Dirk Johrendt
Inorganics 2024, 12(6), 166; https://doi.org/10.3390/inorganics12060166 - 14 Jun 2024
Viewed by 1104
Abstract
Na1.36(Si0.86Ga0.14)2As2.98 and Li1.5Ga0.9Si3.1As4 were synthesized by heating mixtures of the elements at 950 °C. The crystal structures were determined by single crystal X-ray diffraction (Na1.36(Si [...] Read more.
Na1.36(Si0.86Ga0.14)2As2.98 and Li1.5Ga0.9Si3.1As4 were synthesized by heating mixtures of the elements at 950 °C. The crystal structures were determined by single crystal X-ray diffraction (Na1.36(Si0.86Ga0.14)2As2.98: I41/a, Z = 100, a = 19.8772(4) Å, c = 37.652(1) Å; Li1.5Ga0.9Si3.1As4: C2/c, Z = 8, a = 10.8838(6) Å, b = 10.8821(6) Å, c = 13.1591(7) Å). Na1.36(Si0.86Ga0.14)2As2.98 crystallizes similar to NaSi2P3 with interpenetrating networks of vertex-sharing T4 and T5 supertetrahedra. Gallium substitution at the silicon sites increases the charge of the cluster network, which is compensated for by a 36% higher sodium content. Since in contrast to NaSi2P3, all sodium sites are now fully occupied, there is no significant ion mobility, as indicated by 23Na-NMR. Consequently, the total sodium-ion conductivity of Na1.36(Si0.86Ga0.14)2As2.98 amounts to only 1.6(1) × 10−7 S cm−1 and is therefore three orders of magnitude lower than in NaSi2P3. Li1.5Ga0.9Si3.1As4 crystallizes in a new structure type with layers of edge-sharing (Si1−xGax)As4 tetrahedra alternating with layers that contain infinite Sin zigzag chains. Lithium ions reside in channels between the chains, and thus, the structure does not provide three dimensional pathways for ion conduction and the measured total Li-ion conductivity amounts to only 1.3(1) × 10−7 S cm−1. Full article
(This article belongs to the Section Inorganic Solid-State Chemistry)
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17 pages, 12048 KiB  
Article
Preparation and Characterization of Lignin Nanoparticles from Different Plant Sources
by Isidora Ortega-Sanhueza, Victor Girard, Isabelle Ziegler-Devin, Hubert Chapuis, Nicolas Brosse, Francisca Valenzuela, Aparna Banerjee, Cecilia Fuentealba, Gustavo Cabrera-Barjas, Camilo Torres, Alejando Méndez, César Segovia and Miguel Pereira
Polymers 2024, 16(11), 1610; https://doi.org/10.3390/polym16111610 - 6 Jun 2024
Cited by 8 | Viewed by 3585
Abstract
This article presents new research on producing lignin nanoparticles (LNPs) using the antisolvent nanoprecipitation method. Acetone (90%) served as the lignin solvent and water (100%) as the antisolvent, using five types of lignins from various sources. Comprehensive characterization techniques, including NMR, GPC, FTIR, [...] Read more.
This article presents new research on producing lignin nanoparticles (LNPs) using the antisolvent nanoprecipitation method. Acetone (90%) served as the lignin solvent and water (100%) as the antisolvent, using five types of lignins from various sources. Comprehensive characterization techniques, including NMR, GPC, FTIR, TEM, and DLS, were employed to assess both lignin and LNP properties. The antioxidant activity of the LNPs was evaluated as well. The results demonstrated the successful formation of spherical nanoparticles below 100 nm with initial lignin concentrations of 1 and 2%w/v. The study highlighted the crucial role of lignin purity in LNP formation and colloidal stability, noting that residual carbohydrates adversely affect efficiency. This method offers a straightforward, environmentally friendly approach using cost-effective solvents, applicable to diverse lignin sources. The innovation of this study lies in its demonstration of a cost-effective and eco-friendly method to produce stable, nanometric-sized spherical LNPs. These LNPs have significant potential as reinforcement materials due to their reinforcing capability, hydrophilicity, and UV absorption. This work underscores the importance of starting material purity for optimizing the process and achieving the desired nanometric dimensions, marking a pioneering advancement in lignin-based nanomaterials. Full article
(This article belongs to the Special Issue Advances in Applied Lignin Research)
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