CrystEngComm最新文献

Darifenacin (DAR) is a benzofuran derivative used in the treatment of an overactive bladder. In a neat solid phase it shows a propensity to exist in an amorphous form (DAR-A), and in this work we examined the molecular reasons standing behind this propensity. To that purpose we characterized structurally two solvated forms of DAR, a hydrate (DAR-H) and a toluene solvate (DAR-T), using single crystal X-ray diffraction and solid-state NMR spectroscopy, and conducted crystal structure prediction (CSP) calculations to compare the energetic stability of the solvated and non-solvated phases. DAR-A was found to show no preference towards particular intermolecular interactions (no local molecular ordering), a feature associated with a lower likelihood for spontaneous crystallization. The CSP landscape for neat crystal forms showed that the lowest energy structures were at the same time low density ones, a phenomenon not commonly observed for stable neat crystals. Many of these low energy structures contained voids, which is consistent with the experimental tendency of DAR to form solvated rather than neat crystal structures. Indeed, the solvated structures were found to be more energetically favourable, and this was associated with the presence of intermolecular interactions between DAR and solvent molecules, providing an energetic compensation for unfavourable conformational energies. The computational results were consistent with experimental observation of crystallization behaviour of DAR and indicate a low likelihood of ever finding a neat polymorphic form of DAR.

Peroxosolvates of nitrates remain a poorly studied class of compounds among the crystalline adducts of hydrogen peroxide and salts of inorganic acids. Herein, we report the synthesis, crystal structures, and FTIR and thermal studies of four hydrogen peroxide adducts of alkali metal and tetraethylammonium nitrates: KNO₃·0.5H₂O₂, RbNO₃·0.5H₂O₂, RbNO₃·0.5H₂O₂·0.5H₂O, and Et₄N⁺NO₃⁻·2H₂O₂. The peroxosolvates of potassium and rubidium nitrates are found to be non-isomorphous. Solid state DFT calculations were performed to compare the hydrogen bond energy values of the hydrogen peroxide molecule with nitrate anions in the obtained compounds and bromide, chloride, sulfate and carbonate anions in the previously reported crystalline peroxosolvates of the corresponding salts. The calculated hydrogen bond energy values of hydrogen peroxide molecules with the anions correlate with their basicity. For the nitrate anion, these values (29.7–34.7 kJ mol⁻¹) are higher than those for halides and lower than for sulfate and carbonate anions. In addition, the interaction of alkali metal cations with the oxygen atom of hydrogen peroxide was analyzed, revealing a non-covalent binding.

The built-in electric field (IEF) between two components of a heterojunction has been proven to be capable of efficiently separating photogenerated carriers in photocatalysis. However, the rapid charge accumulation near the interface of the heterojunction tends to neutralize this electric field, resulting in the deterioration of the heterojunction performance. Herein, ferroelectric-based BiFeO₃/BiOI-n heterojunctions (BFO/BiOI-n) were prepared utilizing epitaxial growth. BFO not only endows the heterojunctions with stronger ferroelectric polarization, which was confirmed by the hysteresis loop, but also induces a significant redistribution of carriers, which maintains a stronger IEF in BFO/BiOI-n. Furthermore, the ferroelectric polarization of BFO was further regulated via corona poling and the enlarged ferroelectric polarization was also favorable to improve the photocatalytic performance. The optimal PBFO/BiOI-4 sample delivers complete degradation of RhB within 30 minutes and a hydrogen evolution rate of 150 μmol g⁻¹ h⁻¹. The significantly improved photocatalytic performance is attributed to the efficient photogenerated carrier separation synergistically promoted by the IEF in the heterojunction and the polarized electric field (PEF) in BFO. This work provides a feasible scheme for designing ferroelectric-based heterojunction photocatalysts.

This study demonstrates the effect of steric hindrance on the solid-state photoreactivity investigated in four discrete complexes [Cd(9-AnBz)₂(4-StPy)₂(MeOH)₂]·2H₂O (1), [Cd₂(9-AnBz)₄(1-NVP)₄]·2MeOH (2), [Cd₂(9-AnBz)₄(2-NVP)₄] (3), and [Cd(9-AnBz)₂(9-AnVP)₂(MeOH)₂] (4), where 9-AnBz = 9-anthracenyl-4′-benzoate, 4-StPy = (E)-styryl-4-pyridine, 1-NVP = (E)-1-naphthalenevinyl-4′-pyridine, 2-NVP = (E)-2-naphthalenevinyl-4′-pyridine, and 9-AnVP = (E)-9-anthracenylvinyl-4′-pyridine. Their structures have been determined by single-crystal XRD diffraction and the stacking of the arene-containing pyridyl-based auxiliary olefin ligands in these complexes has been analysed. The 4-StPy ligands from two neighbouring complexes were found to stack in a head-to-tail fashion, and thus complex 1 was found to be photoreactive when exposed to sunlight. The process of the photodimerization reaction was further observed to exhibit a photosalient effect when investigated under UV light. With a gradual increase in the steric crowd in the arene moieties of the auxiliary ligands, complexes 2–4 were observed to be photo-inert. Pyridyl-based auxiliary ligands of different steric demands resulted in distinct coordination numbers, geometries, structural diversity, and solid-state photo-reactivity. Solid-state photoluminescence for all complexes 1–4 has been investigated.

This study focuses on enhancing the aqueous dissolution of venetoclax through salt formation. Venetoclax, a BCS class IV B-cell lymphoma-2-selective inhibitor, exhibits very low solubility and bioavailability. Given its multiple protonable groups, salt formation was explored to improve its dissolution properties. Dicarboxylic and sulfonic acids were selected as counterions for salt screening. Ten salts were synthesized and characterized using powder X-ray diffraction, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Intrinsic dissolution rate measurements demonstrated that all salts dissolve faster than the parent drug. The crystal structures of venetoclax, venetoclax fumarate, venetoclax oxalate, and venetoclax napsylate, which all solvated with acetonitrile, and unsolvated venetoclax tosylate were elucidated and described.

We report on an improved crystal growth process, reassessment of the orientation of the optical ellipsoid, and polarized spectroscopy of doped monoclinic magnesium monotungstate (MgWO₄) in a new dielectric frame. A set of crystals, including undoped, Yb³⁺-doped, and Tm³⁺-doped MgWO₄, were grown by the top-seeded solution growth (TSSG) method with K₂W₂O₇ as a solvent. This approach resulted in high-quality crystals with a significantly reduced growth time compared to those grown using Na₂WO₄. The crystal structures were confirmed by powder X-ray diffraction, and the lattice parameters were determined using Le Bail fitting. We review the growth methodology and emphasize the revision of the principal optical axes orientation in this biaxial crystal which differs substantially from previous reports. Polarized Raman spectroscopy was conducted based on this revised orientation. The absorption and stimulated emission cross-sections of the studied ions were derived for the principal light polarizations, comparing these findings with existing results to validate the new dielectric frame orientation.

In the present work, the synthesis conditions and crystal growth as well as the phase transitions, morphology, and luminescence spectra of K(Yb_1−x−yTm_xHo_y)(MoO₄)₂ solid solutions have been studied. The intense white emission of Tm³⁺ and Ho³⁺ ions was obtained in polycrystalline and single crystal samples in the range x + y = 0.01–0.02. The phase formation in the K–(Yb,Tm,Ho)–Mo–O system was studied and single crystals of K(Yb,Tm,Ho)(MoO₄)₂ and (Yb,Tm,Ho)₂Mo₃O₁₂ were grown from the melts at different temperatures. The crystals exhibit white-light luminescence excited with a 980 nm source.

A Ni₆-added polyoxometalate, (NH₄)_0.5Cs_1.5K₄Na₃[Ni(H₂O)₆][{BO(OH)₂}₂Ni₆(OH)(H₂O)₆(SiW₁₀O₃₇)₂]·8H₂O (1), was made with the guidance of the “lacunary-directing synthesis” strategy using a hydrothermal method and characterized by single crystal/powder X-ray diffraction, solid-state UV-vis spectroscopy, FT-IR spectroscopy, and thermogravimetric analysis. The polyoxoanion of 1 could be conceptually constructed by the synergistic directing effect of two dilacunary B-α-SiW₁₀O₃₇ fragments linked by a central [{BO(OH)₂}₂Ni₆(OH)(H₂O)₆]⁹⁺ ({B₂Ni₆}) via Ni–O–W and Ni–O–Si linkages. The {B₂Ni₆} cluster was composed of a V-shaped {Ni₆} core with an angle of 54.6° and further decorated with two BO(OH)₂ groups. Furthermore, 1 could be applied in the Knoevenagel condensation reaction as a Lewis catalyst and exhibited excellent catalytic activity under mild reaction conditions.

It is known that Pb_1−ySn_yTe materials are attractive for studies in the area of topological insulators when y > 0.3–0.4. In this work, a family of heterostructures based on a Pb_1−ySn_yTe/BaF₂/Ca_1−xBa_xF₂/CaF₂/Si(111) epitaxial system was grown via a molecular beam epitaxy method. The lattice parameter values of each sub-layer were determined, and the nature of the elastic strains leading to the mutual inter-influence of sub-layers was estimated. The use of a Ca_1−xBa_xF₂ solid solution enabled a smoother transition in the lattice constant and a reduction in tensile and compressive strains between the sub-layers compared to a heterostructure without the use of this solid solution. Thus, it was shown that the use of a metamorphic buffer layer, including a Ca_1−xBa_xF₂ solid solution, improved the quality of all interfaces within the combined buffer layer by reducing the layer strain. It was observed that the barium fluoride sub-layer exhibited a smaller mismatch in lattice parameters under compressive strain than under tensile strain, which occurred in the absence of a solid solution layer. For CaF₂ growth, a layer-by-layer Frank–van der Merwe growth mechanism was demonstrated, while for Ca_1−xBa_xF₂ growth, the Stranski–Krastanov growth mechanism predominated, and for BaF₂ growth, the Volmer–Weber island growth mechanism was observed. It was confirmed that the CaF₂ lattice rotated at 180° relative to the silicon lattice during high-temperature growth, with subsequent retention of the solid solution and barium fluoride orientations.

Developing fluorescent turn-on probes to monitor hydrogen sulfide (H₂S) in biosystems has attracted significant attention owing to their noninvasiveness, high spatial resolution and superior signal-to-noise ratio. Considering the significant expression level of H₂S in living organisms, it is a great challenge to further expand the response range to several-hundred micromolar levels while maintaining excellent sensitivity for this type of probe. Herein, we proposed a surface manipulation strategy for the highly emissive CuInS₂ quantum dots (CIS QDs) using a recognition group with multiple responses during the assay to construct an H₂S turn-on fluorescent probe. Results demonstrated that the designed CIS/ZnS@Fe³⁺ nanoprobe can react with H₂S via the modes of H₂S-induced reduction of Fe³⁺ and subsequent metal-sulfide precipitation of Fe²⁺, producing a fluorescent signal exhibiting a two-stage linear relationship with the amount of H₂S. As a result, it not only possessed a considerable limit of detection of 0.68 μM and high selectivity but also had an extremely wide detection range of 0–300 μM, and it was capable of H₂S fluorescent imaging in living cells.