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N,N′-Bis(9-(4-chlorophenyl)-9-thioxanthenyl)ethylenediamine (H1) and N,N′-bis(9-(4-chlorophenyl)-9-xanthenyl)ethylenediamine (H2) were investigated as possible separation agents for mixtures of pyridine (PYR) and methylpyridine isomers (2MP, 3MP, and 4MP) through supramolecular chemistry. MPs are present as mixtures in the chemical industry, but fractional distillation is challenging since they have a narrow boiling range, and so alternative and greener separation strategies are necessary. Initially, the host ability of H1 and H2 was assessed for these solvents; each pyridine was enclathrated by both host compounds. When guests competed, H1 and H2 behaved selectively: host affinities were in the order 3MP > PYR > 4MP ≫ 2MP (H1) and 2MP > 3MP > PYR ≫ 4MP (H2). Moreover, H1 was able to separate the 80 : 20, 60 : 40 and 50 : 50 PYR/2MP, 20 : 80 3MP/PYR and 60 : 40 PYR/4MP mixtures: high selectivity coefficients were calculated (K ≥ 10). H2 fared even better: each of the 20 : 80 2MP/PYR, 40 : 60 and 20 : 80 3MP/PYR, all mixtures of PYR/4MP except 20 : 80, all solutions of 2MP/4MP and 20 : 80 3MP/4MP mixtures may be purified in this fashion. Thermal experiments demonstrated that the favoured guest solvents formed the more stable complexes with H1 and H2. Furthermore, the SCXRD analyses provided reasons for the host affinity of H1 for 3MP, relative to the least preferred 2MP, when presented with guest mixtures. 3MP experienced three C–H⋯π close contacts with the host molecule, while this type of interaction was not observed in the 2MP-containing complex. Finally, 4MP was consistently disfavoured by H2 as a result of the fact that this guest solvent was accommodated in wide open multidirectional channels and, as a result, was the least stable complex, confirmed by thermal analysis, while the favoured 2MP formed the most stable complex of the four, being housed in unidirectional channels.

The competition between hydrogen bonding and stacking interactions in the solid-state packing of Z- and E-isomers of methyl pyruvate semicarbazone (1-Z and 1-E) is quantitatively analyzed using a combination of X-ray crystallography, density functional theory (DFT), and energy vector diagrams (EVDs). The E-isomer forms dimers stabilized by resonance-assisted hydrogen bonds (RAHBs) with an interaction energy of −70.4 kJ mol⁻¹, which serve as the building units (BUs) of its columnar-layered crystal structure. In contrast, the Z-isomer exhibits weaker RAHBs (−61.7 kJ mol⁻¹) and relies more heavily on dispersion-driven stacking interactions between hydrogen-bridged quasi-rings, resulting in a distinct layered motif. Solution NMR studies confirm intramolecular hydrogen bonding in 1-Z and present evidence of self-association. This work highlights the delicate balance between classical hydrogen bonds and stacking forces in directing crystal packing, with implications for the design of hydrazone-based functional materials.

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.