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Fedyanin, Ivan V., Konstantin A. Lyssenko, Leonid L. Fershtat, Nikita V. Muravyev i Nina N. Makhova. "Crystal Solvates of Energetic 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane Molecule with [bmim]-Based Ionic Liquids". Crystal Growth & Design 19, nr 7 (4.06.2019): 3660–69. http://dx.doi.org/10.1021/acs.cgd.8b01835.
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André, Vânia, M. Teresa Duarte, Clara S. B. Gomes i Mafalda C. Sarraguça. "Mechanochemistry in Portugal—A Step towards Sustainable Chemical Synthesis". Molecules 27, nr 1 (31.12.2021): 241. http://dx.doi.org/10.3390/molecules27010241.
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In Portugal, publications with mechanochemical methods date back to 2009, with the report on mechanochemical strategies for the synthesis of metallopharmaceuticals. Since then, mechanochemical applications have grown in Portugal, spanning several fields, mainly crystal engineering and supramolecular chemistry, catalysis, and organic and inorganic chemistry. The area with the most increased development is the synthesis of multicomponent crystal forms, with several groups synthesizing solvates, salts, and cocrystals in which the main objective was to improve physical properties of the active pharmaceutical ingredients. Recently, non-crystalline materials, such as ionic liquids and amorphous solid dispersions, have also been studied using mechanochemical methods. An area that is in expansion is the use of mechanochemical synthesis of bioinspired metal-organic frameworks with an emphasis in antibiotic coordination frameworks. The use of mechanochemistry for catalysis and organic and inorganic synthesis has also grown due to the synthetic advantages, ease of synthesis, scalability, sustainability, and, in the majority of cases, the superior properties of the synthesized materials. It can be easily concluded that mechanochemistry is expanding in Portugal in diverse research areas.
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Klorman, Jake A., i Kah Chun Lau. "The Relevance of Lithium Salt Solvate Crystals in Superconcentrated Electrolytes in Lithium Batteries". Energies 16, nr 9 (26.04.2023): 3700. http://dx.doi.org/10.3390/en16093700.
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Based on the unique ubiquity of similar solvate structures found in solvate crystals and superconcentrated electrolytes, we performed a systematic study of four reported solvate crystals which consist of different lithium salts (i.e., LiMPSA, LiTFSI, LiDFOB, and LiBOB) solvated by acetonitrile (MeCN) based on first principles calculations. Based on the calculations, these solvate crystals are predicted to be electronic insulators and are expected to be similar to their insulating liquid counterpart (e.g., 4 M superconcentrated LiTFSI-MeCN electrolyte), which has been confirmed to be a promising electrolyte in lithium batteries. Although the MeCN molecule is highly unstable during the reduction process, it is found that the salt-MeCN solvate molecules (e.g., LiTFSI-(MeCN)2, LiDFOB-(MeCN)2) and their charged counterparts (anions and cations) are both thermodynamically and electrochemically stable, which can be confirmed by Raman vibrational modes through the unique characteristic variation in C≡N bond stretching of MeCN molecules. Therefore, in addition to the development of new solvents or lithium salts, we suggest it is possible to utilize the formation of superconcentrated electrolytes with improved electrochemical stability based on existing known compounds to facilitate the development of novel electrolyte design in advanced lithium batteries.
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Rehman, Abida, Amit Delori, David S. Hughes i William Jones. "Structural studies of crystalline forms of triamterene with carboxylic acid, GRAS and API molecules". IUCrJ 5, nr 3 (6.04.2018): 309–24. http://dx.doi.org/10.1107/s2052252518003317.
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Pharmaceutical salt solvates (dimethyl sulfoxide, DMSO) of the drug triamterene with the coformers acetic, succinic, adipic, pimelic, azelaic and nicotinic acid and ibuprofen are prepared by liquid-assisted grinding and solvent-evaporative crystallization. The modified ΔpK a rule as proposed by Cruz-Cabeza [(2012). CrystEngComm, 14, 6362–6365] is in close agreement with the results of this study. All adducts were characterized by X-ray diffraction and thermal analytical techniques, including single-crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry and thermal gravimetric analysis. Hydrogen-bonded motifs combined to form a variety of extended tapes and sheets. Analysis of the crystal structures showed that all adducts existed as salt solvates and contained the aminopyridinium–carboxylate heterodimer, except for the solvate containing triamterene, ibuprofen and DMSO, as a result of the presence of a strong and stable hemitriamterenium duplex. A search of the Cambridge Structural Database (CSD 5.36, Version 1.18) to determine the frequency of occurrence of the putative supramolecular synthons found in this study showed good agreement with previous work.
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Madusanka, Nadeesh, Mark D. Eddleston, Mihails Arhangelskis i William Jones. "Polymorphs, hydrates and solvates of a co-crystal of caffeine with anthranilic acid". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 70, nr 1 (16.01.2014): 72–80. http://dx.doi.org/10.1107/s2052520613033167.
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A polymorph screen on a new 1:1 co-crystal of caffeine, C8H10N4O2, with anthranilic acid, C7H7NO2, has revealed a rich diversity of crystal forms (two polymorphs, two hydrates and seven solvates, including two sets of isostructural solvates). These forms were prepared by liquid-assisted grinding and solution crystallization, and the crystal structures of nine of these forms have been solved using either single-crystal or powder X-ray data. The structures contain O—H...N and N—H...O hydrogen bonds through which caffeine and anthranilic acid molecules assemble to form zigzag-type chains. These chains can interact in an anti-parallel and offset manner to form cage- or channel-type skeletons within which solvent molecules can be located, giving rise to the diversity of forms observed for this co-crystal. In contrast, an equivalent series of liquid-assisted grinding and solution crystallization experiments with the closely related system of theobromine, C7H8N4O2, and anthranilic acid resulted in the formation of only one 1:1 co-crystal form.
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Suckert, Stefan, Susanne Wöhlert i Christian Näther. "Synthesis, structures, and properties of Mn(II) and Cd(II) thiocyanato coordination compounds with 2,5-dimethylpyrazine as co-ligand". Zeitschrift für Naturforschung B 71, nr 5 (1.05.2016): 381–90. http://dx.doi.org/10.1515/znb-2015-0182.
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AbstractReaction of manganese (II) thiocyanate with 2,5-dimethylpyrazine leads to the formation of three new coordination compounds of compositions Mn(NCS)2(2,5-dimethylpyrazine)2(H2O)2 (1), Mn(NCS)2(H2O)2(MeOH)2-tris(2,5-dimethylpyrazine) solvate (2), and Mn(NCS)2 (H2O)4-tetrakis(2,5-dimethylpyrazine) solvate (3) that were characterized by single crystal X-ray diffraction. In their crystal structures, the Mn(II) cations are sixfold coordinated by two terminally N-bonded thiocyanato anions and two water molecules as well as by two 2,5-dimethylpyrazine ligands (1), two ethanol (2), or two water molecules (3), within slightly distorted octahedra. In compounds 2 and 3, additional 2,5-dimethylpyrazine ligands are located in the cavities of the structures as solvate molecules. X-ray powder diffraction has shown that compounds 1 and 2 cannot be prepared as pure phases and that batches of compound 3 contain only minor traces of a contamination. Differential thermoanalysis and thermogravimetry have revealed that upon heating of compound 3, an intermediate of composition Mn(NCS)2(2,5-dimethylpyrazine) (4) is formed, which cannot be obtained from solution. To mimic the structure of 4, single crystals of a Cd compound of the same composition (5) were prepared from the liquid phase, and single crystal X-ray analysis has shown that it is isotypic to 4.
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Joseph, Stefanie, Christof Suchentrunk i Nikolaus Korber. "Dissolving Silicides: Syntheses and Crystal Structures of New Ammoniates Containing Si52– and Si94– Polyanions and the Role of Ammonia of Crystallisation". Zeitschrift für Naturforschung B 65, nr 9 (1.09.2010): 1059–65. http://dx.doi.org/10.1515/znb-2010-0901.
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The dissolution of the ternary material K6Rb6Si17 in liquid ammonia yields the solvate compound Rb4Si9 ・ 5NH3, which contains fourfold negatively charged nine atom silicon clusters Si94−. Using additionally the [2.2.2] cryptand during the dissolution results in the solvate [K(2.2.2- crypt)]2Si5 ・ 4NH3 , in which the Si52− anion is present in the crystal structure. The Si52− anion has the shape of a nearly ideal trigonal bipyramid. The starting material K6Rb6Si17 contains both Si44− and Si94− Zintl anions. In ammoniate crystal structures, Si94− anions are accessible independently of Si44− anions, and ammonia of crystallisation plays a major role in the observed crystal symmetry. For the cryptate structures of Si52− and Ge52− anions ammonia of crystallisation is obligatory despite the loss of crystal symmetry compared to the crystal structures of the heavier homologues Pb52− and Sn52−.
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Beck, Johannes, i Folker Steden. "Triiodotelluronium Hexafluoroarsenate TeI3[AsF6]. The Crystal Structure of the Hemi SO2 Solvate and the Structure Relation to the Unsolvated Form". Zeitschrift für Naturforschung B 58, nr 8 (1.08.2003): 711–14. http://dx.doi.org/10.1515/znb-2003-0801.
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TeI3[AsF6] is formed from Te, I2, and AsF5 in liquid SO2. At room temperature light red crystals of the hemi SO2 solvate TeI3[AsF6] · 0.5 SO2 are obtained from a saturated solution. The crystal structure (orthorhombic, Pnnm, a=1107.41(2), b=1866.58(3), c=1207.00(2) pm at 123 K, Z =8) consists of pyramidal TeI3+ cations (Te-I = 267 pm), almost regular octahedral [AsF6]− anions and of SO2 molecules which show disorder for the O atom positions. A remarkable feature of the crystal structure is the arrangement of the TeI3+ ions that are pairwise associated, facing each other with the I atoms and forming large voids between each other. This causes the significantly lower density of TeI3[AsF6] · 0.5 SO2 (3.88 Mgm−3) in comparison to the unsolvated form (4.20 Mgm−3, Pass more 1981).
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Zanolla, Debora, Lara Gigli, Dritan Hasa, Michele R. Chierotti, Mihails Arhangelskis, Nicola Demitri, William Jones, Dario Voinovich i Beatrice Perissutti. "Mechanochemical Synthesis and Physicochemical Characterization of Previously Unreported Praziquantel Solvates with 2-Pyrrolidone and Acetic Acid". Pharmaceutics 13, nr 10 (2.10.2021): 1606. http://dx.doi.org/10.3390/pharmaceutics13101606.
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Two new solvates of the widely used anthelminthic Praziquantel (PZQ) were obtained through mechanochemical screening with different liquid additives. Specifically, 2-pyrrolidone and acetic acid gave solvates with 1:1 stoichiometry (PZQ-AA and PZQ-2P, respectively). A wide-ranging characterization of the new solid forms was carried out by means of powder X-ray diffraction, differential scanning calorimetry, FT-IR, solid-state NMR and biopharmaceutical analyses (solubility and intrinsic dissolution studies). Besides, the crystal structures of the two new solvates were solved from their Synchrotron-PXRD pattern: the solvates are isostructural, with equivalent triclinic packing. In both structures acetic acid and 2-pyrrolidone showed a strong interaction with the PZQ molecule via hydrogen bond. Even though previous studies have shown that PZQ is conformationally flexible, the same syn conformation as the PZQ Form A of the C=O groups of the piperazinone-cyclohexylcarbonyl segment is involved in these two new solid forms. In terms of biopharmaceutical properties, PZQ-AA and PZQ-2P exhibited water solubility and intrinsic dissolution rate much greater than those of anhydrous Form A.
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Grassl, Tobias, i Nikolaus Korber. "Crystal structure of rubidium peroxide ammonia disolvate". Acta Crystallographica Section E Crystallographic Communications 73, nr 2 (17.01.2017): 200–202. http://dx.doi.org/10.1107/s2056989017000354.
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The title compound, Rb2O2·2NH3, has been obtained as a reaction product of rubidium metal dissolved in liquid ammonia and glucuronic acid. As a result of the low-temperature crystallization, a disolvate was formed. To our knowledge, only one other solvate of an alkali metal peroxide is known: Na2O2·8H2O has been reported by Grehlet al.[Acta Cryst.(1995), C51, 1038–1040]. We determined the peroxide bond length to be 1.530 (11) Å, which is in accordance with the length reported by Bremm & Jansen [Z. Anorg. Allg. Chem.(1992),610, 64–66]. One of the ammonia solvate molecules is disordered relative to a mirror plane, with 0.5 occupancy for the corresponding nitrogen atom.
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Baptista, João A., Mário T. S. Rosado, Ricardo A. E. Castro, António O. L. Évora, Teresa M. R. Maria, Manuela Ramos Silva, João Canotilho i M. Ermelinda S. Eusébio. "Dihydrofolate Reductase Inhibitors: The Pharmacophore as a Guide for Co-Crystal Screening". Molecules 26, nr 21 (6.11.2021): 6721. http://dx.doi.org/10.3390/molecules26216721.
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In this work, co-crystal screening was carried out for two important dihydrofolate reductase (DHFR) inhibitors, trimethoprim (TMP) and pyrimethamine (PMA), and for 2,4-diaminopyrimidine (DAP), which is the pharmacophore of these active pharmaceutical ingredients (API). The isomeric pyridinecarboxamides and two xanthines, theophylline (THEO) and caffeine (CAF), were used as co-formers in the same experimental conditions, in order to evaluate the potential for the pharmacophore to be used as a guide in the screening process. In silico co-crystal screening was carried out using BIOVIA COSMOquick and experimental screening was performed by mechanochemistry and supported by (solid + liquid) binary phase diagrams, infrared spectroscopy (FTIR) and X-ray powder diffraction (XRPD). The in silico prediction of low propensities for DAP, TMP and PMA to co-crystallize with pyridinecarboxamides was confirmed: a successful outcome was only observed for DAP + nicotinamide. Successful synthesis of multicomponent solid forms was achieved for all three target molecules with theophylline, with DAP co-crystals revealing a greater variety of stoichiometries. The crystalline structures of a (1:2) TMP:THEO co-crystal and of a (1:2:1) DAP:THEO:ethyl acetate solvate were solved. This work demonstrated the possible use of the pharmacophore of DHFR inhibitors as a guide for co-crystal screening, recognizing some similar trends in the outcome of association in the solid state and in the molecular aggregation in the co-crystals, characterized by the same supramolecular synthons.
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Waibel, Markus, i Thomas F. Fässler. "First Incorporation of the Tetrahedral [Sn4]4- Cluster into a Discrete Solvate Na4[Sn4] (NH3)13 from Solutions of Na4Sn4 in Liquid Ammonia". Zeitschrift für Naturforschung B 68, nr 5-6 (1.06.2013): 732–34. http://dx.doi.org/10.5560/znb.2013-3087.
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Treatment of solutions of Na4Sn4 in liquid ammonia with CuMes (Mes=mesityl) and 18-crown-6 afforded crystals of the composition Na4[Sn4] (NH3)13. The structure features anionic units {Na7[Sn4]2} and separate Na cations, both fully solvated by ammonia molecules
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Triandi, Rachmat, i Johannes Beck. "Synthesis and Crystal Structures of Silver Thianthrene Complexes with Weakly Coordinating Anions". Zeitschrift für Naturforschung B 62, nr 10 (1.10.2007): 1291–97. http://dx.doi.org/10.1515/znb-2007-1010.
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Two novel silver complexes with thianthrene (TA) as a ligand have been synthesized in the poorly coordinating solvent liquid sulfur dioxide, using silver salts with weakly coordinating anions [BF4]− and [SbF6]−. Both colorless compounds contain discrete molecular entities and SO2 molecules included in the crystal structure. Selection of crystals and the diffraction data collection were performed at low temperatures (123 K). The tris(μ-thianthrene-κ2S)disilver(I) bis(hexafluoroantimonate) sulfur dioxide solvate [Ag2(TA)3][SbF6]2·5SO2 (1) (monoclinic, P21/c, a = 21.644(3), b = 12.4216(4), c = 21.934(3) Å , β = 115.04(1)°, Z = 4) is made up of complexes bearing three TA units acting as bridging ligands with both S atoms towards two Ag+ ions with d(Ag+-Ag+) = 2.911 Å giving the [Ag2(TA)3]2+ unit approximately D3h molecular symmetry. The bis(μ-thianthrene-κ2S)disilver(I) bis(tetrafluoroborate) sulfur dioxide solvate [Ag2(TA)2][BF4]2・3SO2 (2) (monoclinic, C2/c, a = 21.0045(6), b = 7.4553(2), c = 22.6024(6) A° , β = 109.65(0)°, Z = 4) is made up of [Ag2(TA)2]2+units with two bridging TA units coordinating two Ag+ ions with d(Ag+-Ag+) = 2.925 Å giving the complexes approximately D2h molecular symmetry. Weak, secondary bonds between Ag+ and the F atoms of the anions, such as Ag···F-SbF5 = 2.862(4) Å in 1 or Ag···F-BF3 = 2.773(2) Å in 2, and with O atoms of SO2 molecules link the complexes with the anions and the solvate molecules, respectively.
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Choquesillo-Lazarte, Duane, Cristóbal Verdugo-Escamilla i Juan Manuel García-Ruiz. "Novel solid forms of the analgesic drug ethenzamide". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C995. http://dx.doi.org/10.1107/s2053273314090044.
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The interest in multicomponent solid forms has increased in the last years within the pharmaceutical industry and also the solid-state community due to the possibility of obtaining materials with new properties [1]. Crystallization strategies, supported by solvent- and solid-based techniques, have also received attention in the search and development of methodologies for the screening of multicomponent crystals. In this work, ethenzamide, an anti-inflammatory and analgesic drug, was selected as a model drug to develop cocrystals on the basis of the synthon types using a series of phenolic coformers. Ethenzamide cocrystals and cocrystal solvates have been reported recently [2,3]. Liquid Assisted Grinding (LAG) and solution methods were used as synthetic tools. Attempts to produce cocrystals by LAG and Reaction Crystallization led to the formation of polycrystalline material. The solids obtained were then characterized by powder X-ray diffraction (PXRD), FT-IR and Raman spectroscopy. Recrystallization by slow solvent evaporation was carried out when the above-referred techniques strongly suggest the formation of a new solid form. The structure of five new multicomponent solids has been determined by single crystal X-ray diffraction. Additional stability studies have been performed at controlled relative humidity conditions and followed by PXRD.
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Seidel, Anne, Mareike Weigel, Lisa Ehrlich, Robert Gericke, Erica Brendler i Jörg Wagler. "Molecular Structures of the Silicon Pyridine-2-(thi)olates Me3Si(pyX), Me2Si(pyX)2 and Ph2Si(pyX)2 (py = 2-Pyridyl, X = O, S), and Their Intra- and Intermolecular Ligand Exchange in Solution". Crystals 12, nr 8 (28.07.2022): 1054. http://dx.doi.org/10.3390/cryst12081054.
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A series of pyridine-2-olates (pyO) and pyridine-2-thiolates (pyS) of silicon was studied in solid state and in solution. The crystal structures of Me3Si(pyO) (1a), Me3Si(pyS) (1b), Me2Si(pyO)2 (2a), Me2Si(pyS)2 (2b), Ph2Si(pyO)2 (3a) and Ph2Si(pyS)2 (3b) were determined by X-ray diffraction. For that purpose, crystals of the (at room temperature) liquid compounds 1a and 1b were grown in a capillary on the diffractometer. Compounds 1a, 1b, 2a, 2b and 3a feature tetracoordinate silicon atoms in the solid state, whereas 3b gave rise to a series of four crystal structures in which the Si atoms of this compound are hexacoordinate. Two isomers (3b1 with all-cis arrangement of the C2N2S2 donor atoms in P, and 3b2 with trans S-Si-S axis in P21/n) formed individual crystal batches, which allowed for their individual 29Si NMR spectroscopic study in the solid state (the determination of their chemical shift anisotropy tensors). Furthermore, the structures of a less stable modification of 3b2 (in C2/c) as well as a toluene solvate 3b2×(toluene) (in P) were determined. In CDCl3, the equimolar solutions of the corresponding pairs of pyO and pyS compounds (2a/2b and 3a/3b) showed substituent scrambling with the formation of the products Me2Si(pyO)(pyS) (2c) and Ph2Si(pyO)(pyS) (3c), respectively, as minor components in the respective substituent exchange equilibrium.
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Cox, Jordan M., Ian M. Walton, Gage Bateman, Cassidy A. Benson, Travis Mitchell, Eric Sylvester, Yu-Sheng Chen i Jason B. Benedict. "Solvent exchange in a metal–organic framework single crystal monitored by dynamicin situX-ray diffraction". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 73, nr 4 (25.07.2017): 669–74. http://dx.doi.org/10.1107/s2052520617008447.
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Understanding the processes by which porous solid-state materials adsorb and release guest molecules would represent a significant step towards developing rational design principles for functional porous materials. To elucidate the process of liquid exchange in these materials, dynamicin situX-ray diffraction techniques have been developed which utilize liquid-phase chemical stimuli. Using these time-resolved diffraction techniques, the ethanol solvation process in a flexible metal–organic framework [Co(AIP)(bpy)0.5(H2O)]·2H2O was examined. The measurements provide important insight into the nature of the chemical transformation in this system including the presence of a previously unreported neat ethanol solvate structure.
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Suchentrunk, Christof, i Nikolaus Korber. "Reduktion von Isochinolin und Indol mit Cäsium in flüssigem Ammoniak / Reduction of Isoquinoline and Indole with Cesium in Liquid Ammonia". Zeitschrift für Naturforschung B 58, nr 10 (1.10.2003): 990–96. http://dx.doi.org/10.1515/znb-2003-1009.
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Isoquinoline and indole were reduced with solutions of cesium in liquid ammonia and the resulting crystalline compounds isolated as ammonia-rich solvate crystals. The reduction of isoquinoline yields the anion bisisoquinoline-2,2’-diide in the compound Cs2C18H14N2 · (7/2) NH3 as the result of a coupling reaction. Indole is reduced to the 5,8-dihydroindolide anion in the ammoniate CsC8H8N · 3NH3. Both anions display interactions between their aromatic π-systems and the cesium cations.
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Li, Hsin-Yi, i Yen-Ho Chu. "Exploiting Solvate Ionic Liquids for Amine Gas Analysis on a Quartz Crystal Microbalance". Analytical Chemistry 89, nr 10 (28.04.2017): 5186–92. http://dx.doi.org/10.1021/acs.analchem.7b00857.
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Helfenritter, Christoph, i Matthias Kind. "Multi-Component Diffusion in the Vicinity of a Growing Crystal". Crystals 12, nr 6 (20.06.2022): 872. http://dx.doi.org/10.3390/cryst12060872.
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Co-crystallization from multi-component solutions occurs in many solids formation processes. The measurement or simulative description of concentration courses in the fluid vicinity of a growing crystalline substrate is difficult for such systems. These are relevant with respect to developing concentrations of crystallizing components at the solid-liquid interface due to diffusion fluxes in the solution. Concentrations may change such that unintended crystalline states can develop. With Fickian multi-component diffusion modeling we are able to simulate the timely evolution of the concentrations in the diffusion boundary layer during crystallization of various solid entities. Not only single solvate crystallization is modeled but also co-crystallization from multi-component solutions with different solvate states. The simulations are run with the assumption that diffusion limitation dominates. However, the model can be easily adapted to integration limitation. The interdependence of two diffusing components is taken into account in Fick’s multicomponent diffusion with a diffusion coefficient between these two components. We show that the consideration of so called cross-diffusion effects between dissolved materials can be neglected during crystallization of single decahydrates and during co-crystallization of anhydrous electrolytes. The presented model is also capable of fitting crystal growth kinetics with single point desupersaturation measurements in a thin film. In addition to the study of the kinetic parameters, the simulation allows the determination of the spatial concentration evolution from the single point concentration measurements.
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Christopherson, Jan-Constantin, Karlie P. Potts, Oleksandr S. Bushuyev, Filip Topić, Igor Huskić, Kari Rissanen, Christopher J. Barrett i Tomislav Friščić. "Assembly and dichroism of a four-component halogen-bonded metal–organic cocrystal salt solvate involving dicyanoaurate(I) acceptors". Faraday Discussions 203 (2017): 441–57. http://dx.doi.org/10.1039/c7fd00114b.
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We describe the use of dicyanoaurate ions as linear ditopic metal–organic acceptors for the halogen bond-driven assembly of a dichroic metal–organic cocrystal based on azobenzene chromophores. Structural analysis by single crystal X-ray diffraction revealed that the material is a four-component solid, consisting of anticipated anionic metal–organic halogen-bonded chains based on dicyanoaurate ions, as well as complex potassium-based cations and discrete molecules of the crown ether 15-crown-5. Importantly, the structural analysis revealed the parallel alignment of the halogen-bonded chains required for dichroic behaviour, confirming that crystal engineering principles developed for the design of halogen-bonded dichroic organic cocrystals are also applicable to metal-based structures. In the broader context of crystal engineering, the structure of the herein reported dichroic material is additionally interesting as the presence of an ion pair, a neutral azobenzene and a molecule of a room-temperature liquid make it an example of a solid that simultaneously conforms to definitions of a salt, a cocrystal, and a solvate.
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Easton, Max E., Kai Li, Hatem M. Titi, Steven P. Kelley i Robin D. Rogers. "Controlling the Interface between Salts, Solvates, Co-crystals, and Ionic Liquids with Non-stoichiometric Protic Azolium Azolates". Crystal Growth & Design 20, nr 4 (11.02.2020): 2608–16. http://dx.doi.org/10.1021/acs.cgd.9b01733.
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Su, Rui, Zhangcheng Liu, Haris Naeem Abbasi, Jinjia Wei i Hongxing Wang. "Visible-Light Activation of Photocatalytic for Reduction of Nitrogen to Ammonia by Introducing Impurity Defect Levels into Nanocrystalline Diamond". Materials 13, nr 20 (14.10.2020): 4559. http://dx.doi.org/10.3390/ma13204559.
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Nitrogen impurity has been introduced in diamond film to produce a nitrogen vacancy center (NV center) toward the solvated electron-initiated reduction of N2 to NH3 in liquids, giving rise to extend the wavelength region beyond the diamond’s band. Scanning electron microscopy and X-ray diffraction demonstrate the formation of the nanocrystalline nitrogen-doped diamond with an average diameter of ten nanometers. Raman spectroscopy and PhotoLuminescence (PL) spectrum show characteristics of the NV0 and NV− charge states. Measurements of photocatalytic activity using supraband (λ < 225 nm) gap and sub-band gap (λ > 225 nm) excitation show the nitrogen-doped diamond significantly enhanced the ability to reduce N2 to NH3 compared to the polycrystalline diamond and single crystal diamond (SCD). Our results suggest an important process of internal photoemission, in which electrons are excited from negative charge states into conduction band edges, presenting remarkable photoinitiated electrons under ultraviolet and visible light. Other factors, including transitions between defect levels and processes of reaction, are also discussed. This approach can be especially advantageous to such as N2 and CO2 that bind only weakly to most surfaces and high energy conditions.
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Kelley, Steven P., Asako Narita, John D. Holbrey, Keith D. Green, W. Matthew Reichert i Robin D. Rogers. "Understanding the Effects of Ionicity in Salts, Solvates, Co-Crystals, Ionic Co-Crystals, and Ionic Liquids, Rather than Nomenclature, Is Critical to Understanding Their Behavior". Crystal Growth & Design 13, nr 3 (22.02.2013): 965–75. http://dx.doi.org/10.1021/cg4000439.
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Stompel, Semyon, Edward T. Samulski, Jack Preston, Benjamin S. Hsiaok, KennCorwin H. Gardner i Hsiang Shih. "A Thiophene-Based Liquid Crystalline Aromatic Polyamide". High Performance Polymers 9, nr 3 (wrzesień 1997): 229–49. http://dx.doi.org/10.1088/0954-0083/9/3/004.
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We have synthesized a liquid crystalline, aromatic polyamide from p-phenylene diamine (PPD) and 2, 5-thiophene dicarboxylic acid (Th). The new polymer, poly( p-phenylene thiophenylamide), abbreviated PPD-Th, like its terephthalic acid precursor, poly( p-phenylene terepthalamide) (PPD-T), exhibits a lyotropic mesophase in concentrated sulphuric acid solutions. Polarizing optical microscopy and deuterium NMR show that concentrated PPD-Th solutions exhibit nematic-to-isotropic phase transitions at a much lower temperature than comparable PPD-T solutions. More importantly, unlike PPD-T, lyotropic PPD-Th solutions do not form a crystallo-solvate complex gel phase at room temperature, i.e. the fluid PPD-Th mesophase persists below 300 K enabling the spinning of PPD-Th fibres from a lyotropic dope at ambient temperatures. Thermogravimetric analysis shows that the 2, 5-thiophene heterocycle in the PPDTh backbone does not significantly diminish its thermal stability relative to that of PPD-T. Preliminary x-ray diffraction results show that PPD-Th crystallizes in a tentative two-chain, orthorhombic unit cell with dimensions a = 3.73 Å, b = 5.04 Å and c = 25.20 Å (fibre axis). The fibre repeat corresponds to two chemical repeats related by a twofold screw axis. Mechanical properties (tensile strength, modulus and elongation to break) are presented for as-spun and heat-treated PPD-Th fibres.
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Dong, Linhan, Dongdong Feng, Yu Zhang, Heming Dong, Zhiqi Zhao, Jianmin Gao, Feng Zhang, Yijun Zhao, Shaozeng Sun i Yudong Huang. "Effects of Solubilizer and Magnetic Field during Crystallization Induction of Ammonium Bicarbonate in New Ammonia-Based Carbon Capture Process". Energies 15, nr 17 (26.08.2022): 6231. http://dx.doi.org/10.3390/en15176231.
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As a chemical absorption method, the new ammonia carbon capture technology can capture CO2. Adding ethanol to ammonia can reduce the escape of ammonia to a certain extent and increase the absorption rate of CO2. The dissolution and crystallization of ethanol can realize the crystallization of ammonium bicarbonate and generate solid products. The induction of the crystallization process is influenced by many parameters, such as solution temperature, supersaturation, and solvating precipitant content. The basic nucleation theory is related to the critical size of nucleation. Accurate measurement of the induction period and investigating relevant factors can help to assess the nucleation kinetics. The effects of solubilizer content, temperature, and magnetic field on the induction period of the crystallization process of ammonium bicarbonate in the ethanol–H2O binary solvent mixture and determining the growth mechanism of the crystal surface by solid–liquid surface tension and surface entropy factor are investigated. The results indicate that under the same conditions of mixed solution temperature, the crystallization induction period becomes significantly longer, the solid–liquid surface tension increases, and the nucleation barrier becomes more significant and less likely to form nuclei as the content of solvating precipitants in the components increases. At the same solubilizer content, there is an inverse relationship between the solution temperature and the induction period, and the solid–liquid surface tension decreases. The magnetic field can significantly reduce the induction period of the solvate crystallization process. This gap tends to decrease with an increase in supersaturation; the shortening reduces from 96.9% to 84.0%. This decreasing trend becomes more and more evident with the rise of solvent content in the solution. The variation of surface entropy factor under the present experimental conditions ranges from 0.752 to 1.499. The growth mode of ammonium bicarbonate in the ethanol–H2O binary solvent mixture can be judged by the surface entropy factor as continuous growth.
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Hu, Zheyao, i Jordi Marti. "In Silico Drug Design of Benzothiadiazine Derivatives Interacting with Phospholipid Cell Membranes". Membranes 12, nr 3 (17.03.2022): 331. http://dx.doi.org/10.3390/membranes12030331.
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The use of drugs derived from benzothiadiazine, a bicyclic heterocyclic benzene derivative, has become a widespread treatment for diseases such as hypertension, low blood sugar or the human immunodeficiency virus, among others. In this work we have investigated the interactions of benzothiadiazine and four of its derivatives designed in silico with model zwitterionic cell membranes formed by dioleoylphosphatidylcholine, 1,2-dioleoyl-sn-glycero-3-phosphoserine and cholesterol at the liquid–crystal phase inside aqueous potassium chloride solution. We have elucidated the local structure of benzothiadiazine by means of microsecond molecular dynamics simulations of systems including a benzothiadiazine molecule or one of its derivatives. Such derivatives were obtained by the substitution of a single hydrogen site of benzothiadiazine by two different classes of chemical groups, one of them electron-donating groups (methyl and ethyl) and another one by electron-accepting groups (fluorine and trifluoromethyl). Our data have revealed that benzothiadiazine derivatives have a strong affinity to stay at the cell membrane interface although their solvation characteristics can vary significantly—they can be fully solvated by water in short periods of time or continuously attached to specific lipid sites during intervals of 10–70 ns. Furthermore, benzothiadiazines are able to bind lipids and cholesterol chains by means of single and double hydrogen-bonds of characteristic lengths between 1.6 and 2.1 Å.
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Sunkara, Mahendra Kumar. "Plasma-molten Metal and/or Liquid Interactions for Materials/Chemical Processing". ECS Meeting Abstracts MA2020-01, nr 17 (1.05.2020): 1106. http://dx.doi.org/10.1149/ma2020-01171106mtgabs.
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Several grand challenges in energy storage and conversion need the discovery of functional materials that many agree will be composed of complex compositions at nanoscale. In this regard, plasma based materials processing has been shown to be promising for combinatorial techniques and scalable processing. The use of plasma oxidation of liquid precursors allows for creation of metastable complex oxide particles with compositional control.1 A number of examples will be discussed in which the above two techniques are currently being used for accelerating the development of a variety of catalysts including electrocatalysts and materials for storage applications. This talk will highlight our efforts to understand the role of plasmas under two categories: (a) the synergistic effects hydrogen and nitrogen plasma interactions with molten metals;2 and (b) the oxygen plasma-liquid droplet interactions.3 To gain insights into these mechanisms we have studied the interaction of hydrogen and nitrogen plasmas with low melting point metals, primarily with gallium. Absorption/desorption experiments as well as theoretical-computational calculations were performed. Experiments have shown an increment of adsorbed gaseous species into the molten metal in the presence of plasmas. In the case of oxygen plasma-liquid droplet interactions for creating complex oxides, the role of solvated electrons, oxygen radicals and heating effects will be discussed. Finally, the use of plasmas for achieving liquid phase epitaxial growth of GaN and related materials will be discussed.4 Author acknowledge primary funding support from NSF Solar Project (DMS 1125909), and NSF EPSCoR (1355438). References 1. P. Ajayi, S. Kumari, D. Jaramillo-Cabanzo, J. Spurgeon, J. Jasinski and M.K. Sunkara, “A rapid and scalable method for making mixed metal oxide alloys for enabling accelerated materials discovery”, J. of Materials Research, 31 (11), 1596-1607(2016) 2. L. Carreon, D.F. Jaramillo-Cabanzo, I. Chaudhuri, M. Menon and M.K. Sunkara, “Synergistic interactions of H2 and N2 with molten gallium in the presence of plasma”, Journal of Vacuum Science and Technology A, 36, 021303 (2018). 3. P. Ajayi, M. Z. Akram, W. H. Paxton, J. B. Jasinski and M. K. Sunkara, “Nucleation and Growth Mechanisms During Complex Oxide Formation Using Plasma Oxidation of Liquid Precursors”, Submitted (2019) 4. Jaramillo, J. Jasinski and M. Sunkara, “Liquid Phase Epitaxial Growth of Gallium Nitride”, Crystal Growth and Design, 19, 11, 6577-6585(2019)
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Glasser, Leslie. "The effective volumes of waters of crystallization: non-ionic pharmaceutical systems". Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 75, nr 5 (31.08.2019): 784–87. http://dx.doi.org/10.1107/s2052520619010436.
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The physical properties of organic solids are altered when hydrated (and, more generally, when solvated) and this is of particular significance for pharmaceuticals in application; for instance, the solubility of a hydrate is less than that of its parent. The effective volumes of waters of crystallization for non-ionic pharmaceuticals (where the `effective' volume is the difference per water molecule between the hydrate volume and the volume of the anhydrous parent) are here examined. This investigation contrasts with our earlier study of effective volumes of waters of crystallization for ionic materials where the coulombic forces are paramount. Volumetric properties are significant since they correlate strongly with many thermodynamic properties. Twenty-nine hydrate/parent systems have been identified, and their volumetric properties are reported and analysed (apart from aspartame and ephedrine for which the structural data are inconsistent). Among these systems, the data for paracetamol are extensive and it is possible to differentiate among the volumetric properties of its three polymorphs and to quantify the effect of temperature on their volumes. The effective volumes in both ionic and non-ionic systems are similar, with a median effective volume of 22.8 Å3 for the non-ionic systems compared with 24.2 Å3 for the ionic systems, and both are smaller than the molecular volume of 30 Å3 of ambient liquid water – which appears to be an upper limit to the effective volumes of waters of crystallization under ambient conditions. These results will be supportive in checking and confirmation of hydrated crystal structures and in assessing their thermodynamic properties.
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Dranka, Maciej, i Janusz Zachara. "Coordination modes of novel 4,5-dicyanoimidazolato ligand in alkali metal salts". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C650. http://dx.doi.org/10.1107/s2053273314093498.
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As the use of lithium batteries became more and more wide-spread, the importance of the research on novel salts for batteries' electrolytes grew more and more important. The focus has been put on designing novel lithium and sodium salts which dissociate well in aprotic solvents and are electrochemically and thermally stable. Salts with heteroaromatic anions such as 2-trifluoromethane-4,5-dicyanoimidazolate (LiTDI) [1,2] are a promising alternative for the salts commonly used as charge carriers in lithium and sodium batteries. The class of new 4,5-dicyanoimidazolates ligands is based on N-heterocyclic five-membered ring substituted with nitrile group. Such a type of anions possesses four nitrogen donor centers able to coordinate cation, and is characterized by charge delocalization, both on imidazole ring and cyano substituents resulting in extended π electron system. In solid as well as liquid electrolytes one should expect the co-existence of a variety of ionic species, such as iosolated anions and cations solvated by solvent molecules, ionic pairs, for which the coordination sphere of cations is completed with solvent molecules, as well as dimers and aggregates with varied stoichiometry. The observed degree of aggregation depends mostly on the coordination properties of anions, their ability to form hydrogen bonds and their compatibility with the acidic properties of cations. The increase of the salt concentration should result in association process and the emergence of higher aggregates, up to polymeric systems, possessing structure of chains, ribbons, layers or networks. In order to define the coordination ability of the class of new ligands, we examined their organization modes in the alkali metal salts and have found a wide variety of mentioned motifs. Discovering and understanding the phenomena related to the organization of such systems in the solid state is crucial for the elaboration of novel electrolytes and should give information about cation and anion coordination in electrolytes. Our single-crystal diffraction studies have shown that new salts comprising 4,5-dicyano-2-(trifluoromethyl)imidazolato anion are interesting from the point of view of their crystalline structure, offering variety of possible coordination modes and are, therefore, worthy of examination.
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Park, Inhee, i Helmut Baltruschat. "Atomic-Scale Friction Study: Underpotential Deposition (UPD) of Silver on I-Modified Au(111) in Aprotic Electrolyte". ECS Meeting Abstracts MA2022-01, nr 23 (7.07.2022): 1179. http://dx.doi.org/10.1149/ma2022-01231179mtgabs.
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Friction in general is one of the main sources of energy loss, and therefore finding ways for better controlling friction is of uttermost importance. Atomic-scale friction is measured using electrochemical lateral force microscopy (EC-LFM) where the AFM tip slides on the surface of electrode under electrochemical control. It helps us to understand interfacial and tribological behavior on nanoscale. In ionic liquids (ILs) including solvate ILs, the friction as function of normal load has been studied on HOPG and Au(111), which shows that the structure of ions is a decisive factor for the friction behavior [1-4]. Our interest was focused on the adsorption of foreign metals, ranging from (sub)monolayer (underpotential deposition (UPD)) to multilayer (bulk) deposition and the adsorption of organic adsorbates, and its influence on friction as function of potential on single crystal electrodes in aqueous electrolyte[5-7]. The underpotential deposition (UPD) of silver had often been studied on gold in aqueous electrolyte since the lattice constants of silver and gold are fairly identical (Å, Å) [8-12]. Previous results clearly show that the Ag UPD process is very sensitive to the presence of other adsorbates (e.g. SO4 2-, ClO4 -). Especially, the Ag UPD on iodine covered surface of Au(111) shows completely different atomic structures after the 1st, 2nd, and 3rd Ag UPD compared to the results on Au(111) [9, 13]. In this study, we investigate the interfacial properties on I-modified Au(111) during the Ag UPD in aprotic electrolyte. We observed two sets of Ag UPD peaks in cyclic voltammetry (CV). The charge density for these peaks is about 216 µC/cm² close to the theoretical charge density for the monolayer (222 µC/cm²). We observed the iodine structure at low normal load (FN < 20nN), which shows that the iodine adlayer on Au(111) and Ag monolayer forms a (˅3×˅3)R30°. It indicates that the iodine adlayer is stable during the Ag UPD. At high normal load, the AFM tip penetrates into iodine layer and reveals the structure of Au(111) or Ag monolayer depending on the potential. It is remarkable that there is no irreversible wear during the penetration of AFM tip meaning that the iodine structure appears again with decreasing normal loads. At high normal load where the tip penetrates into iodine layer and interacts with substrates (Au and Ag), the friction on Ag monolayer is higher than on Au(111). Interestingly, even though the cyclic voltammetry (CV) shows that the amount of water in the electrolyte has minor influence, the friction increases with an increase in water content on the I/Ag/Au(111). [1] H. Li, M.W. Rutland, R. Atkin, Physical Chemistry Chemical Physics 15 (2013) 14616-14623. [2] H. Li, M.W. Rutland, M. Watanabe, R. Atkin, Faraday discussions 199 (2017) 311-322. [3] O.Y. Fajardo, F. Bresme, A.A. Kornyshev, M. Urbakh, Scientific Reports 5 (2015) 6. [4] A. Elbourne, J. Sweeney, G.B. Webber, E.J. Wanless, G.G. Warr, M.W. Rutland, R. Atkin, Chem. Commun. 49 (2013) 6797-6799. [5] S. Iqbal, S. Wezisla, N. Podgaynyy, H. Baltruschat, Electrochimica Acta 186 (2015) 427-435. [6] M. Nielinger, H. Baltruschat, Physical Chemistry Chemical Physics 9 (2007) 3965-3969. [7] N. Podgaynyy, S. Iqbal, H. Baltruschat, Surface Science 631 (2015) 67-72. [8] T. Hachiya, K. Itaya, Ultramicroscopy 42 (1992) 445-452. [9] K. Ogaki, K. Itaya, Electrochimica acta 40 (1995) 1249-1257. [10] M. Espladiu, M. Schneeweiss, D. Kolb, Physical Chemistry Chemical Physics 1 (1999) 4847-4854. [11] C.H. Chen, S.M. Vesecky, A.A. Gewirth, Journal of the American Chemical Society 114 (1992) 451-458. [12] P. Mrozek, Y.-e. Sung, M. Han, M. Gamboa-Aldeco, A. Wieckowski, C.-h. Chen, A.A. Gewirth, Electrochimica acta 40 (1995) 17-28. [13] S. Sugita, T. Abe, K. Itaya, The Journal of Physical Chemistry 97 (1993) 8780-8785.
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Han, Sang-Don, Roger D. Sommer, Paul Boyle, Zhi-Bin Zhou, Victor G. Young Jr i Wesley A. Henderson. "Electrolyte Solvation and Ionic Association: Part IX. Structures and Raman Spectroscopic Characterization of LiFSI Solvates". Journal of The Electrochemical Society, 13.10.2022. http://dx.doi.org/10.1149/1945-7111/ac9a07.
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Abstract The bis(fluorosulfonyl)imide anion N(SO2F)2- (i.e., FSI-) (also referred to as bis(fluorosulfonyl)amide (i.e., FSA-) and imidodi(sulphuryl fluoride)) has attracted tremendous interest in recent years for its utility in both lithium salts and ionic liquids for battery electrolyte applications. To facilitate the understanding of the characteristics of this anion, crystal structures are reported here for the uncoordinated anion in LiFSI-based solvates with cryptand CRYPT-222 and tetraglyme (G4). These crystalline solvates were analyzed by Raman spectroscopy to aid in assigning the Raman bands to the modes of ion coordination found in liquid electrolytes. These structures, as well as a thorough review of other relevant crystallographic data, provide insights into the rather remarkable properties of the FSI- anion with regard to solvate formation and electrolyte properties.
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Richert, Clemens, Wolfgang Frey, Alexander Schwenger i Tim Berking. "Transitions in Solvate Crystals of a Tetraaryladamantane". Helvetica Chimica Acta, 17.08.2023. http://dx.doi.org/10.1002/hlca.202300102.
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Obtaining high‐resolution structures of liquid compounds can be difficult. Encapsulating them in the lattice of a larger organic molecule acting as crystallization chaperone is one option to overcome this difficulty. Tetraaryladamantane ethers can play the role of chaperones, accommodating a range of different guest molecules in their crystals. How well ordered crystalline arrangements for molecules of different shape are achieved is not clear. Cases in which more than one structure is found may shed light on this phenomenon. Here we report low order cubic crystal structures of 1,3,5,7‐tetrakis(2,4‐dimethoxyphenyl)adamantane (TDA) encapsulating ortho‐xylene or cyclohexane, together with better ordered structures obtained after warming the crystals to 60 °C. Evidence for cubic crystal systems was also found for limonene, hexachlorobutadiene and eucalyptol, with a transition to a triclinic system for the former two, but no transition up to 70 °C for the latter. These findings indicate that some solvate structures of TDA can readily undergo structural transitions to less solvated, better ordered systems. Crystals obtained by rapid thermal crystallization may be kinetically trapped states, and the transition to a solvate‐free crystal system appears to have a kinetic barrier that depends strongly on the structure of the liquid guest molecules encapsulated in the lattice.
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Miao, Shurui, Michael Gradzielski i Gregory Warr. "Micelle structure of nonionic surfactants containing carbon dioxide moieties in protic ionic liquids". Colloid and Polymer Science, 29.06.2023. http://dx.doi.org/10.1007/s00396-023-05139-5.
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AbstractPartial substitution of ethylene oxide with carbon dioxide moieties can yield greener nonionic surfactants with comparable functionalities. In water, studies showed that the incorporation of CO2 moieties suppresses the formation of liquid crystalline phases at high concentrations. A similar reduction in solvation and suppression of liquid crystal formation is observed here in the ionic liquids ethylammonium nitrate and propylammonium nitrate. Small-angle neutron scattering is used to study the solvation and packing of micelles in ionic liquids as functions of temperature, concentration, and content of CO2 moieties. By comparing with aqueous solutions, this work shows that while the nature of surfactant-solvent interaction is comparable among water and alkylammonium nitrate ILs, their behaviours in the solvated micelle shell are different. The lack of liquid crystalline phases should be attributed to the small excluded volume of micelles, which can be fine-tuned via ion design and choice of solvent. Graphical Abstract
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Krzton-Maziopa, Anna. "Intercalated Iron Chalcogenides: Phase Separation Phenomena and Superconducting Properties". Frontiers in Chemistry 9 (22.06.2021). http://dx.doi.org/10.3389/fchem.2021.640361.
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Organic molecule-intercalated layered iron-based monochalcogenides are presently the subject of intense research studies due to the linkage of their fascinating magnetic and superconducting properties to the chemical nature of guests present in the structure. Iron chalcogenides have the ability to host various organic species (i.e., solvates of alkali metals and the selected Lewis bases or long-chain alkylammonium cations) between the weakly bound inorganic layers, which opens up the possibility for fine tuning the magnetic and electrical properties of the intercalated phases by controlling both the doping level and the type/shape and orientation of the organic molecules. In recent years, significant progress has been made in the field of intercalation chemistry, expanding the gallery of intercalated superconductors with new hybrid inorganic–organic phases characterized by transition temperatures to a superconducting state as high as 46 K. A typical synthetic approach involves the low-temperature intercalation of layered precursors in the presence of liquid amines, and other methods, such as electrochemical intercalation, intercalant or ion exchange, and direct solvothermal growths from anhydrous amine-based media, are also being developed. Large organic guests, while entering a layered structure on intercalation, push off the inorganic slabs and modify the geometry of their internal building blocks (edge-sharing iron chalcogenide tetrahedrons) through chemical pressure. The chemical nature and orientation of organic molecules between the inorganic layers play an important role in structural modification and may serve as a tool for the alteration of the superconducting properties. A variety of donor species well-matched with the selected alkali metals enables the adjustment of electron doping in a host structure offering a broad range of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed, involving the influence of the chemical and electrochemical nature of intercalating species on the crystal structure and critical issues related to the superconducting properties of the hybrid inorganic–organic phases. Mutual relations between the host and organic guests lead to a specific ordering of molecular species between the host layers, and their effect on the electronic structure of the host will be also argued. A brief description of a critical assessment of the association of the most effective chemical and electrochemical methods, which lead to the preparation of nanosized/microsized powders and single crystals of molecularly intercalated phases, with the ease of preparation of phase pure materials, crystal sizes, and the morphology of final products is given together with a discussion of the stability of the intercalated materials connected with the volatility of organic solvents and a possible degradation of host materials.
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Fusaro, Luca, Nikolay Tumanov, Giacomo Saielli i Riccardo Montis. "Insights into the self-assembly of fampridine hydrochloride: how the choice of the solvent affects the crystallization of a simple salt". Pure and Applied Chemistry, 27.04.2023. http://dx.doi.org/10.1515/pac-2022-1208.
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Abstract Crystalline materials and crystallization processes play an important role in several fields of science, such as pharmaceuticals, material science, pigments, optoelectronics, catalysis and energy storage. Understanding and defining the right conditions of crystallization is therefore crucial. Among the several factors influencing the crystallization of a given compound, the choice of the solvent system is perhaps one of the most important. The nature of solvent–solute interactions can indeed have a role in promoting specific molecular assemblies, therefore affecting crystallisation rates of a crystal and often resulting in the nucleation of different polymorphs and solvates. Here we investigated the role of a binary mixture of solvent (water/acetone) in the crystallisation of a simple salt of 4-aminopyridinium chloride. Previous results on this compound showed that when crystallised from water it forms a simple hydrate structure, while in the presence of acetone, it undergoes a liquid-liquid phase separation, followed by the crystallisation of a complex structure belonging to the Frank–Kasper (FK) phases, a particular family of topologically close-packed structures never observed in small and rigid molecules. To broaden the understanding of how such a simple molecule may crystallise as an FK phase, we carried out the crystallization of the complex phase by antisolvent diffusion (in a mixture of water/acetone) and that of the monohydrate phase in water, monitoring the liquid precursors by liquid-state NMR. In particular, we applied 1H, 13C, 14N, 17O, and 35/37Cl NMR as a function of the concentration of 4APH+Cl− until the moment when precipitation of the crystalline phases occurred. Variations of chemical shifts, T1 relaxation times of 13C signals, and full-width at half-maximum of the signals of quadrupolar nuclei were also measured. The spatial proximity between the different species in the solution was investigated by NOE experiments. In order to support these results, we also performed Molecular Dynamics simulations, investigating the potential solute/solvents interactions. The results strongly suggest that acetone, instead of behaving as an anti-solvent, interacts directly with the solute, preventing the formation of the simple monohydrate structure and, at the same time, promoting specific molecular aggregations.