Crystal Structures Of Salts Research Articles

Synthesis, crystal structure, supramolecular assembly inspection via hirshfeld surface analysis and computational investigation of the pyrimethamine-based salts

In current research work, two salts abbreviated as 5DECA and 2DECA derived from pyrimethamine and aceclofenac are synthesized by using a simple method of reflux in methanol. The crystal structures of salts are investigated by the single-crystal X-ray diffraction (SC-XRD) technique. The supramolecular architecture of both compounds contained N-H⋯O, N-H⋯N, C-H⋯O, off-set π⋯π stacking, and C-O⋯π interactions. The difference in supramolecular architecture is that in 5DECA, O-H⋯O and C-H⋯π interactions are present, whereas in 2DECA, N-H⋯Cl, C-H⋯Cl, and C-Cl⋯π interactions are present. The presence of water molecule in 5DECA is the main reason for the difference between the supramolecular architecture of compounds. The intermolecular interactions in terms of interatomic contacts are probed by Hirshfeld surface analysis (HSA). Void analysis is performed to understand the mechanical response of crystals. Computational studies, conducted at the DFT/B3LYP//ma-def2-SVP level of theory, confirmed that the supramolecular assemblies in these systems are governed by π-π and N-H⋯O interactions. These calculations also determined several key factors, comprising structural features, molecular electrostatic potential (MEP), the HOMO-LUMO energy gap (ΔE), and Infrared spectroscopic absorption peaks.

Hydrogen-bonding interactions in the salts 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, 2,4,6-triaminopyrimidin-1-ium N-phenylantharanilate and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate.

Three salts, namely, 2,4,6-triaminopyrimidin-1-ium sorbate dihydrate, C4H8N5+·C6H7O2-·2H2O, (I), 2,4,6-triaminopyrimidin-1-ium N-phenylanthranilate, C4H8N5+·C13H10NO2-, (II), and 2,4,6-triaminopyrimidin-1-ium p-toluenesulfonate, C4H8N5+·C7H7O3S-, (III), were synthesized, characterized by X-ray diffraction techniques and their supramolecular interactions investigated. In all three crystal structures, protonation of the pyrimidine moiety occurs at the N1 position and is reflected in a widening of the C-N-C bond angle. In salts (I)-(III), the primary acid-base interaction occurs through a pair of N-H...O hydrogen bonds to give a heterodimeric R22(8) synthon. Salts (II) and (III) form a discrete centrosymmetric base pair that produces a homodimeric R22(8) synthon and salt (I) forms a water-mediated base pair resulting in a tetrameric R44(12) synthon. The supramolecular patterns exhibited by sulfonate salt (III) mimic the patterns of carboxylate salt (II) and both exhibit a DADA array (D = donor and A = acceptor) quadruple hydrogen-bonded pattern. The crystal structures of salts (I) and (III) are stabilized by offset and face-to-face aromatic π-π stacking interactions, respectively. The resulting architectures in salts (I)-(III) are a supramolecular sheet with a rosette-like architecture in (I), a supramolecular sheet-like architecture in (II) and a three-dimensional supramolecular network in (III).

Iodides and polyiodides of l-arginine

Exploring l-arginine salts, particularly halogenides, for their nonlinear optical properties has been a subject of significant interest. While various l-arginine salts were extensively studied, their iodide counterparts remained elusive until recent investigations. This study aims to synthesize and characterize l-argininium(+) iodide (l-ArgH)(I) (I), to reinvestigate l-argininium(2+) bis-iodide (l-ArgH2)(I)2 (II), and explore l-argininium(2+) bis-triiodide (l-ArgH2)(I3)2 (III), l-argininium(+) triiodide (l-ArgH)(I3) (IV) and bis-l-argininium(+) triiodide pentaiodide (l-ArgH)2(I3)(I5) (V). Crystal structures of salts (I-III) were determined to elucidate their molecular arrangements. Infrared and Raman spectra of all five compounds were registered and discussed. Electronic band structures of the salts (I-III) were determined by quantum chemical calculations.

Spectroscopy of Ammonium Occupying Symmetry-Inappropriate Positions in Crystal Structures of Salts

Spectroscopy of Ammonium Occupying Symmetry-Inappropriate Positions in Crystal Structures of Salts

1-(4-Bromo-2,3,5,6-tetrafluoropheyl)-3-(3-phenylbenzyl)-4-methylimidazolium Bromide

In this paper, we report on the crystal structure of salt 1-(4-bromo-2,3,5,6-tetrafluorophenyl)-3-(3-phenylbenzyl)-4-methylimidazolium bromide, 3, synthesized by the sequential nucleophilic attack of 4-methylimidazole on bromopentafluorobenzene and then 3-phenylbenzyl bromide. The salt was characterized by 1H, 13C, and 19F NMR spectroscopy and mass spectrometry.

Preparation, characterization, and crystal structures of novel sophocarpine salts with improvements on stability and solubility

Crystal engineering has proved to be an effective and reliable approach to tailor the physicochemical properties of active pharmaceutical ingredients. In this work, three novel sophocarpine salts were prepared and reported, named sophocarpine-hesperetin (SC-HES), sophocarpine-L-(-) malic acid monohydrate (SC-LMA MH), and sophocarpine-p-hydroxybenzoic acid monohydrate (SC-PHBA MH). The crystal structures of the salts were confirmed by infrared spectroscopy and single crystal X-ray diffraction. SC-HES exhibited a laminated molecular stacking structure, SC-LMA MH formed a wavy layered structure, while sophocarpine molecules filled in the voids of the reticular structure to form the 3D structure of the SC-PHBA MH. Thermal analysis shows that after salification, the melting point of the compound increased from 78°C to over 120°C, overcoming its low melting point. Lattice energy and Hirshfeld surface analysis indicated that lower lattice energy provides better thermal stability of the crystal and intermolecular hydrogen bonds (O–H···O and N→H···O) play a key role in the construction of the crystal structures. In addition, the water solubility and hygroscopicity of the three salts were characterized and discussed, with SC-HES exhibiting satisfying physical stabilities and hygroscopicity, and SC-LMA MH achieving 6.7 times solubility than the free base, which provides viable options for solid dosage form development of the drug.

A guanidium salt as a chaotropic agent for aqueous battery electrolytes.

This study investigates a salt design principle for aqueous battery electrolytes by combining chaotropic ions, guanidium cations (Gdm) and bis(trifluoromethanesulfonyl)imide anions (TFSI), forming GdmTFSI. This salt's crystal structure was solved via single-crystal X-ray diffraction and characterized using Fourier-transform infrared spectroscopy. Study reveals that GdmTFSI salt disrupts the hydrogen bonding network of aqueous solutions, impacting water reactivity at electrochemical interfaces.

Preparation, QTAIM and Single‐Crystal Exploration of the Pyrimethamine‐Based Co‐Crystal Salts with Substituted Benzoic Acids

AbstractThe effective preparation of pyrimethamine based co‐crystal salts with substituted benzoic acids (4‐nitrobenzoic acid 1 and 5‐chlorosalicylic acid 2) in methanol has been reported. The crystal structure of salt 1 and 2 is acquired through the x‐rays diffraction technique. Hirshfeld surface analysis elaborates the comparative study of the non‐covalent interactions in salt 1 and 2. In order to theoretically evaluate the non‐covalent interactions between molecular ions in salts 1 and 2, DFT and TD‐DFT calculations of molecular salts were performed. FMO and GRD analyses were performed to evaluate the reactivity of molecular ions. While, NBO, AIM and NCI analyses were performed to explore the non‐covalent interactions between cation and anions of molecular salts 1 and 2. The calculations demonstrated that salt 1 has H‐bond slightly stronger than salt 2 due to the withdrawing effect of ‐NO2 substituent group. The molecular anions reactivity allows different patterns of non‐covalent interactions that affect the salts arrangement in the crystal.

Further study on energetic salts of TNATT anion

Six energetic salts based on fully nitroamino-functionalized fused-triazole were synthesized. All salts were characterized by IR, multinuclear NMR spectroscopy, thermal analysis and elemental analysis. The crystal structures of salts 2, 3, and 6 were confirmed by single-crystal X-ray diffraction. The densities of all salts lie in the range between 1.77 and 1.83 g cm−3, whilst their decomposition temperatures range within 142–200 °C. Most energetic salts are slightly more sensitive than RDX. The calculated detonation pressures and velocities (Gaussian 09 and EXPLO5) of salts 2–7 range within 21.7–39.3 Gpa and 7867–9401 m s−1, respectively. Salt 7 exhibits a high density (1.83 g cm−3), acceptable thermal stability (Td = 179 °C) and sensitivity (IS = 7 J, FS = 216 N), and excellent detonation performance (vD = 9401 m s−1, P = 39.3 GPa), which suggest that salt 7 may well have promising applications as high-energy–density materials.

Aluminum-Ion Electrolytes with Weakly Coordinating Anions

The conventional chloroaluminate ionic liquid electrolytes for rechargeable aluminum (Al) batteries are challenged by intrinsic limitations including corrosivity and poor chemical stability due to the active chloride content. Here, we report the first synthesis and characterizations of an Al “simple salt” electrolyte composed of aluminum hexafluorophosphate (Al(PF6)3) in dimethyl sulfoxide (DMSO). Al(PF6)3 salt was synthesized via the reaction between triethylaluminium (Et3Al) and ammonium hexafluorophosphate, and purified via recrystallization. The single crystal X-ray diffraction reveals that the Al3+ cation is solvated with six DMSO molecules (Al(DMSO)6(PF6)3) in the salt crystal structure. The 0.25 M Al(PF6)3 solution in DMSO demonstrates high ionic conductivity at approximately 1.3×10-2 S cm-1. With characterizations including nuclear magnetic resonance spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy (XPS), we demonstrate the reversibility of Al deposition-stripping in the electrolyte, which can be improved by the addition of trace amount of Et3Al as the electrolyte additive. The side reaction involving the reductive decomposition of DMSO to form aluminum oxide during Al deposition is identified by a combination of XPS and gas chromatography/electron ionization-mass spectrometry. Another Al-ion electrolyte with weakly coordinating tetrakis(hexafluoroisopropyloxy) borate ((B[hfip]4)-) anion in DME was also synthesized and characterized. These Al-ion electrolytes with weakly coordinating anions exhibit distinct chemical and electrochemical properties comparing with chloroaluminate ionic liquid electrolytes. They create an opportunity to develop new Al electrolyte system.

Synthesis of monophase two‐dimensional α‐Si3N4 nanoplatelets via an ionothermal route

AbstractMonophase α‐Si3N4 was prepared by a salt melt strategy using Si as a starting material. The results showed that molten salt enhanced the conversion of Si to monophase α‐Si3N4, and some as‐synthesized α‐Si3N4 nanoparticles had a hexagonal platelet morphology. The α‐Si3N4 hexagonal nanoplatelets had an average lateral dimension of about 170 nm and a thickness of about 5.2 nm. The nitridation of Si in molten salt was investigated by a thermal quenching method, and the silicon halide intermediate products were detected by X‐ray photoelectron spectroscopy. Silicon halides possessing higher reactive activity facilitated the nitridation of Si and nucleation of α‐Si3N4. Furthermore, the lattice mismatch between α‐Si3N4 and the salts was calculated, suggesting that the lateral growth of α‐Si3N4 nanoplatelets had been guided by the salt crystal structure. Based on the results, the relevant formation mechanism of α‐Si3N4 nanoplatelets was proposed.

Synthesis, Photochromic Properties, and Crystal Structures of Salts Containing a Pyridinium-Fused Spiropyran: Positive and Negative Photochromism in the Solution and Solid State.

Salts containing the merocyanine form of a pyridinium-fused spiropyran ([6'-MC]X; X = I and PF6) were prepared, and their crystal structures were determined. In addition, the photochromic properties of the salts were spectroscopically and kinetically investigated. In the solution state, the salts exhibited negative photochromism. Theoretical calculations revealed that the negative photochromism of the salt originates from the drastic stabilization of the merocyanine structure by electron delocalization of the pyridinium ring. Furthermore, the salts containing the merocyanine and spiropyran forms ([6'-MC]I, [6'-MC]PF6, and [6'-SP]PF6) were obtained by recrystallization. The crystals of [6'-SP]PF6 exhibited positive photochromism in the solid state; however, no photochromism was observed in the [6'-MC]X crystals.

Crystal structures of salts and cocrystal of 1,3,5-triazine derivatives with thiophene carboxylic acid derivatives: an investigation on supramolecular interactions

Present work gives an account of different types of non covalent interactions encountered in the supramolecular architectures of new salts and cocrystal formed between derivatives of 1,3,5-triazine and thiophene carboxylic acid. The novel salts formed between derivatives of thiophene carboxylic acid and 1,3,5-triazine are 2, 4-diamino-6-methyl-1,3,5-triazin-1-ium 5-carboxythiophene-2-carboxylate monohydrate, C4H8N5+·C6H3O4S1−·H2O (I) and 2,4-diamino-6-methyl-1,3,5-triazin-1-ium 3-bromothiophene-2-carboxylate monohydrate, C4H8N5+·C5H2O2S1Br 1 − ·H2O (II). The new cocrystal is a 1:1 cocrystal formed between 2,4-diamine-6-phenyl-1,3,5-triazine and 2,5-dichlorothiophene-3-carboxylic acid, C9H9N5·C5H2O2S1Cl2 (III). The newly synthesized salts (I and II) and cocrystal (III) have been characterized by single-crystal X-ray diffraction. Supramolecular heterosynthons, homosynthons observed via N–H···O, N–H···N and O–H···N hydrogen bonds are also discussed. Anion···π interaction between carboxylate oxygen and aromatic rings of thiophene and triazine are observed in salt (I). π···π interaction is present between thiophene and triazine rings in salt (II). R 2 2 (8) ring motif is formed in cocrystal (III) via N–H···O and O–H···N hydrogen bonds. Further stabilisation of cocrystal (III) via Cl···O, Cl···Cl interactions as well as π···π interactions (triazine···triazine rings and triazine···phenyl rings) are also investigated.

Crystal and Molecular Structures of Two Salts Based on Polyamine Deribatives

The crystal structures of salts (C18H22N3)(NO3) (I) and (C8H24N4)[ZnCl4]Cl2(II), based on protonated polyamines (diethylenetriamine and N,N′-bis(2-aminoethyl)piperazine) are studied by single crystal X-ray diffraction. Salt I exhibits a wave-like 1D chain formed by N-H⋯O hydrogen bonds from monoprotonated (C18H22N3)+ cations and NO 3 − anions. In salt II, multi-protonated N,N′-bis(2-aminoethyl)piperazinium ions are connected into two types of infinite subloop chains through N-H⋯Cl and C-H⋯Cl halogen bonding contacts from (C8H24N4)4+ cations and [ZnCl4]2− and Cl− anions. The analysis of the Hirshfeld surfaces shows the intermolecular interactions involved in the crystal structures. The corresponding quantitative information is presented by fingerprint plots.

Crystal and molecular structures of two salts based on polyamine deribatives

The crystal structures of salts (I) and (II), (C18H22N3)(NO3) and (C8H24N4)[ZnCl4]Cl2, based on protonated polyamines (diethylenetriamine and N,N′-bis(2-aminoethyl)piperazine) are studied by single-crystal X-ray diffraction. Salt (I) exhibits a wave-like 1D chain formed by N—H···O hydrogen bonds from mono-protonated (C18H22N3)+ cations and NO3− anions. In salt (II), multi-protonated N,N′-bis(2-aminoethyl)piperazinium ions are connected into two types of infinite subloop chains through N—H···Cl and C—H···Cl halogen-bonding contacts from (C8H24N4)4+ cations, and [ZnCl4]2− and Cl− anions. Analysis of the Hirshfeld surfaces show the intermolecular interactions involved within the crystal structures. Corresponding quantitative information are presented by fingerprint plots.

Assessing the Risk of Salt Disproportionation Using Crystal Structure and Surface Topography Analysis

Salt disproportionation is a major issue for pharmaceutical products containing a salt form of a weakly basic drug, because conversion to the free base during processing or storage in the presence of excipients may negatively impact stability and bioperformance of the drug product. Several factors influencing disproportionation tendency have been elucidated; however, a complete mechanistic understanding of this phenomenon is still lacking. Specifically, it is unclear if the crystal structure of the salt plays a role, beyond influencing the salt solubility. Herein, by utilizing model compounds with similar pKa and pHmax values, and hence similar thermodynamic driving forces for disproportionation, we demonstrate that salt crystal structure appears to play a major role in influencing disproportionation tendency. Some salts with low pHmax values were found to be resistant to disproportionation, while other systems transformed to the free base following contact with the basic excipient, magnesium stearate. Fo...

An Unusual Layered Crystal Packing Gives Rise to a Superior Thermal Stability of Energetic Salt of 3,6‐Bishydrazino‐1,2,4,5‐tetrazine

Five energetic salts of 3,6‐bishydrazino‐1,2,4,5‐tetrazine (BHT), namely (BHT)2(NTO)3 (3), (BHT)(BTT)·2H2O (4), (BHT)(DNP)2 (5), (BHT)(NATr)2 (6), and (BHT)(FOX‐7)2 (7), were synthesized and fully characterized by elemental analysis, FT‐IR, and mass spectra. The crystal structures of salts 3 and 4 were obtained and determined. Sensitivities towards outside stimuli and thermal behaviors of all the compounds were investigated, besides, thermodynamics of both 3 and 4 were calculated as well. The compounds 3–7 exhibit splendid thermal stabilities and satisfactory sensitivities simultaneously. Notably, unlike the previously known layered packing, compound 4 was found to adopt an unusual layered crystal packing with arch layers alternately arranged upward or downward. It may play an important role in contributing to its superior thermal stability (350 °C), providing an enlightening thinking to design new highly thermal stable energetic materials.

Novel pharmaceutical salts of albendazole

Novel pharmaceutical salts of albendazole drugs are crystallized with sulfonic acids and carboxylic acids. The disorder of the thiopropyl chain in the parent crystal structure is resolved in the salt crystal structures.

Substituent Effects on the Crystal Structures of Salts Prepared from (R)-2-Methoxy-2-(1-naphthyl)propanoic Acid and (R)-1-Arylethylamines

The crystal structures of salts 6–9 prepared from (R)-2-methoxy-2-(1-naphthyl)propanoic acid [(R)-MαNP acid, (R)-1] and (R)-1-arylethylamines [salt 6, (R)-1-(4-methoxyphenyl)ethylamine∙(R)-1; salt 7, (R)-1-(4-fluorophenyl)ethylamine∙(R)-1; salt 8, (R)-1-(4-chlorophenyl)ethylamine∙(R)-1; and salt 9, (R)-1-(3-chlorophenyl)ethylamine∙(R)-1] were elucidated by X-ray crystallography. The solid-state associations and conformations of the MαNP salts were defined using the concepts of supramolecular- and planar chirality, respectively, and the crystal structures of salts 6–9 were interpreted as a three-step hierarchical assembly. The para-substituents of the (R)-1-arylethylammonium cations were found on sheet structures consisting of 21 columns. Thus, salts possessing smaller para-substituents, that is, salt 7 (p-F) and salt 9 (p-H), and larger para-substituents, that is, salt 6 (p-OMe) and salt 8 (p-Cl), crystallized in the space groups P21 and C2, respectively. Additionally, weak intermolecular interactions, that is, aromatic C–H···π, C–H···F, and C–H···O interactions, were examined in crystalline salts 6–9.

The Crystal Structure of the More-soluble Mosher’s Salt

The crystal structure of salt 4 prepared from (S)-3,3,3-trifluoro-2-methoxy-2-phenylpropanoic acid [(S)-MTPA, (S)-1] and (R)-1-phenylethylamine [(R)-PEA, (R)-2] was determined using X-ray crystallography. The (S)-MTPA anion showed an unusual conformation. The closest ion-pair joined with a methoxy-group-assisted salt bridge and aromatic C–H⋯π interaction in a unique supR association. The aromatic C–H⋯π interactions between the 21 columns were not effective. These results clarified the mechanism of Mosher’s enantioresolution of (RS)-1 with (R)-2 in combination with the previously reported crystal structure of the diastereomeric salt 3 [(R)-1·(R)-2].