CrystEngComm最新文献

The hydrogen-bonding ability of XeF₂ is an important factor influencing its chemical properties and reactivity, yet structurally characterised examples of hydrogen-bonded xenon fluorides remain rare. In this work, three salt cocrystals containing hydrogen-bonded xenon difluoride and hexafluoridoarsenate salts of protonated perfluoroamides—CF₃C(OH)NH₂[AsF₆]·XeF₂, C₂F₅C(OH)NH₂[AsF₆]·XeF₂, and C₃F₇C(OH)NH₂[AsF₆]·XeF₂—were synthesised and structurally characterised. Diverse hydrogen-bonding motifs were observed, and the first crystallographically characterised examples of N–H⋯FXeF hydrogen bonds are presented. In total, eleven new crystal structures are reported, including two perfluoroamides, three protonated and two hemiprotonated perfluoroamides, and one salt cocrystal containing an oxonium ion. The XeF₂-containing cocrystals demonstrate that XeF₂ reliably functions as a hydrogen-bond acceptor and readily forms hydrogen-bonded cocrystals. These findings broaden the scope of noble-gas chemistry and highlight the potential of noble-gas fluorides for cocrystal formation.

Like other factors (internal – substituents and nucleophile; external – coordination, cooperation, solvent polarity, etc.), the chalcogen atom Ch (O, S, Se or Te) replacement at element–Ch⋯nucleophile chemical leitmotifs can also be used as a powerful strategy in the regulation of chalcogen bond parameters (strength and directionality). In this work, we analyze the effect of chalcogen atoms on the strength and directionality of chalcogen bonding (ChB) in various classes of organic compounds taken from the Cambridge Structural Database (CSD). Based on the experimental data (from CSD) and theoretical calculations, we conclude that the expected trend (O ≪ S < Se < Te) for enhancing strength and directionality of ChB does not always occur due to weak characters of Ch⋯nucleophile interactions.

All-inorganic, lead-based perovskite quantum dots (QDs) exhibit exceptional optoelectronic properties, positioning them as highly promising materials for a range of applications. However, their conventional synthesis typically relies on environmentally hazardous chemicals, including toxic solvents such as dimethylformamide (DMF), which pose serious health and ecological risks. This study addresses these concerns by employing dihydrolevoglucosenone (Cyrene), a bio-based and environmentally benign solvent, as a green alternative. CsPbI₃ QDs were synthesized via a facile, ligand-free reprecipitation method. Structural and morphological analyses using XRD, TEM, and Raman spectroscopy confirmed the formation of the γ-CsPbI₃ phase. By using ethanol and toluene as antisolvents, QDs with average particle sizes of 2.2 nm and 4.2 nm were obtained, respectively. Notably, a bright blue emission, not previously reported for CsPbI₃ QDs, was observed and is attributed to strong quantum confinement resulting from their ultra-small dimensions. A photoluminescence quantum yield (PLQY) of 70% was achieved. This study emphasizes the sustainable development of innovative materials with diverse applications, demonstrating the potential of eco-friendly approaches in advancing perovskite research.

In recent years, low-dimensional organic–inorganic hybrid metal halides have been widely studied in optoelectronics owing to their broadband emission and high quantum yields. However, there has been limited progress in blue-emitting material development. To address this challenge, we prepared two new zero-dimensional (0D) cadmium-based hybrid halides, [MeOP]CdBr₄ (MeOP = 1-(2-methoxyphenyl)piperazine) and [FPhP]CdBr₄ (FPhP = 1-(2-fluorophenyl)piperazine) with blue broadband emissions, originating from the radiative recombination of self-trapped excitons (STEs). Furthermore, a stable white light-emitting diode (LED) was fabricated using [MeOP]CdBr₄ as blue phosphor, which achieved a high color rendering index (CRI) of 95.4. This study not only introduces two new blue light-emitting hybrid materials but also highlights their potential in solid-state lighting applications.

Two-dimensional (2D) organic–inorganic halide perovskites (OIHPs) have attracted extensive attention due to their solution processability, structural diversity and tuneable optoelectronic properties. However, there are very few reports on wide-bandgap OIHPs for ultraviolet (UV) detection. Herein, a novel layered wide-bandgap OIHP, [C₄N₂H₁₄][CdBr₄], was synthesized by a facile hydrothermal method. The non-centrosymmetric structure of [C₄N₂H₁₄][CdBr₄] was solved by single-crystal X-ray diffraction (XRD) and the second harmonic generation (SHG) test. This compound exhibits a wide optical bandgap (E_g) of approximately 3.88 eV and a long carrier lifetime of about 641 μs. Compared to the reported centrosymmetric phase of [C₄N₂H₁₄][CdBr₄], our sample achieved a superior responsivity of 32.19 uA W⁻¹ under 254 nm illumination with a fast response speed of τ_r = 283 μs. This work provides a promising strategy for designing and manufacturing new layered OIHPs as candidate materials for solar-blind UV detection.

Three new crystalline organic salts (COSs) comprising 4,4′-biphenyldisulfonic acid (bpds) and different bipyridyl derivatives—2,2′-bipyridine (22bpy), 1,2-di(4-pyridyl)ethylene (bpee), and 2,5-di(pyridin-4-yl)-1,3,4-oxadiazole (bpdoz)—have been synthesized and characterized in terms of structure and proton conductivity. The organic salts, [bpds][22bpy] (1), [bpds][bpee]·2H₂O (2), and [bpds][bpdoz]·H₂O (3), form two- or three-dimensional (2D/3D) hydrogen-bonded networks. In each salt, proton transfer from the sulfonic acid group to the bipyridyl nitrogen acceptor results in the formation of ionic heterosynthons. The proton conductivities of the compounds were measured at 90 °C and 95% relative humidity, yielding maximum values of 8.69 × 10⁻⁵ S cm⁻¹ for 1, 1.09 × 10⁻³ S cm⁻¹ and 1.27 × 10⁻⁴ S cm⁻¹ for both 2 and 3. The strong humidity dependence of conductivity, coupled with activation energies of 0.51 eV for 1, and 0.56 and 0.43 eV for 2 and 3, respectively, suggests a proton transport mechanism consistent with the vehicle mechanism, facilitated by crystalline water molecules and extended hydrogen-bonded networks. Notably, the enhanced proton conduction observed in 2 is attributed to its continuous 1D hydrogen-bonded chain composed of –SO₃⁻⋯H₂O linkages, which provides a more efficient pathway for proton mobility. The foregoing results provide not only three new solid-state proton conductors but also a bipyridyl–organodisulfonate strategy for the designing and building proton conducting crystalline organic salts.

Cocrystals of 1-azaanthracene and several naphthols were prepared by cocrystallization using the solvent evaporation and grinding methods. Their crystal structures were elucidated by X-ray crystallography and PXRD. While cocrystallization of 1-azaanthracene and 2-hydroxynaphtharene (2-HNP) in a 1 : 1 ratio afforded cocrystal (AA)·(2-HNP) (1), cocrystallization in a 2 : 1 ratio produced cocrystal (AA)₂(2-HNP) (2). When 2,6-dihydroxy- and 2,7-dihydroxynaphtharenes were used instead of 2-HNP, corresponding cocrystals 3 and 4 were obtained, respectively. The X-ray crystallographic analyses of 1 to 4 revealed that these cocrystals are composed of a common supramolecular dual-synthon assembled by hydrogen bonds and cation–π interactions, with AA molecules arranged in face-to-face and head-to-tail fashion. The observed supramolecular dual-synthon is thought to be the result of cooperation between hydrogen bonding and cation–π interactions. Interestingly, the hydroxy group of 2-HNP in cocrystal 2 exhibited significant disorder at the 2- and 6-positions of the naphthalene ring with a 50% probability, behaving as if it were 2,6-dihydroxynaphthalene having two OH groups. In fact, cocrystal (AA)₂(2-HNP) (2) was found to have nearly the same crystal structure as (AA)₂·(2,6-DHNP) (3). UV irradiation of cocrystals 1 to 4 gave antiHT dimer quantitatively, while irradiation of cocrystals 1′–4′, which were formed by grinding, afforded antiHT dimers along with antiHH dimers.

We report a comparative high-pressure crystallographic study of the RS- and S-forms of 9-fluoro-3-methyl-10-(4-methylpiperazin-1-yl)-7-oxo-2,3-dihydro-7H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylic acid, encompassing ofloxacin (O), γ-levofloxacin (Lγ), and levofloxacin hemihydrate (LH). Single-crystal and X-ray powder diffraction experiments reveal all three compounds are relatively soft and compressible due to dominant dispersive intermolecular interactions via parallel molecular packing of the main bodies. Each form undergoes distinct pressure-induced phase transitions, with Lγ exhibiting a low transition pressure at 1.14 GPa, while LH displays a unique sensitivity to the water content of the pressure-transmitting medium. Under inert conditions, LH remains stable up to ∼5.1 GPa before a transition to a lower-symmetry polymorph but using certain media it can undergo a phase transition to a new unidentified phase. O shows subtle structural changes above 4.65 GPa in methanol–ethanol medium, though no definitive phase transition was observed in the single-crystal form. These findings provide critical insights into the pressure-dependent behaviour of fluoroquinolone antibiotics, with implications for solid form selection, formulation design, and mechanical stability during pharmaceutical processing.

Two approaches are proposed for obtaining heterospin complexes with an anion-radical of difurazanopyrazine L – a paramagnetic derivative of 4H,8H-bis(1,2,5-oxadiazolo)[3,4-b:3′,4′-e]pyrazine. Aqua 3d metal complexes [ML₂(H₂O)₄]·2H₂O (M = Ni and Co) were synthesized using saturated solutions of reagents with a large excess of M(NO₃)₂. Ammine complexes [ML₂(NH₃)₄] (M = Ni and Cu) were obtained from the reaction of M(NO₃)₂ with NaL(H₂O)₃ in a stoichiometric ratio in the presence of concentrated aqueous ammonia (28%). In all complexes, metal ions coordinate L via N atoms of the pyrazine ring. Molecules of the complexes are linked into a framework by hydrogen bonds. It was found that in [ML₂(NH₃)₄] strong antiferromagnetic exchange interactions are realized between anion-radicals from neighboring molecules, determining the magnetic behavior of the phase as a whole. Whereas in [ML₂(H₂O)₄]·2H₂O, the exchange interactions are ferromagnetic in nature. This is due to the presence of water molecules in the structure, which provide a displacement of the complex molecules relative to each other and, as a consequence, a weakening of the interactions between adjacent L.

Drug discovery and development is an indispensable sector of R&D, and it is of immense significance due to its relevance and direct impact on human life. However, the discovery of new drugs is an evolving and onerous process with critically low success rates, and the majority of potential drugs face physicochemical limitations. Among the known drugs, poor solubility is a serious limitation, and about 90% of discovered drugs and 40% of commercial drugs are class II and IV drugs with poor aqueous solubility. Crystal engineering has appeared as a facile, quicker, and green approach to address the physicochemical limitations of drugs, including their poor aqueous solubility, through a non-covalent strategy involving the development of polymorphs, pharmaceutical co-crystals, and organic salts. This perspective includes a discussion on the definition, classification, and nomenclature of binary crystal forms; a basic understanding of the design method of pharmaceutical co-crystals (ΔpK_a rule, coformer screening, and synthon concept); synthetic methods and scale-up processes of co-crystallization; crystal nucleation; phase diagrams; and opportunities and challenges in the area.