Crystal Growth & Design最新文献

A novel cyanoxime, 2-oximino-2-cyano-N-pyrrolidine-acetamide (further HPyrCO), was synthesized and characterized by spectroscopic methods, thermal analysis, and X-ray crystallography. The structure revealed eight independent molecules with elaborate intermolecular H-bonding in the asymmetric unit and adoption of the trans-anti configuration of the cyanoxime. Henceforth, a series of Ni(II) coordination compounds, crystallohydrates, with this new cyanoxime was obtained from aqueous solutions, with four complexes isolated from the same system after filtration of the main product and subsequent crystallization of new products from the mother liquor. These were RED, the main product [Ni(PyrCO)₂(H₂O)₂](H₂O), and two differently colored polymorphs GREEN [Ni(PyrCO)₂(H₂O)₂] and VIOLET [Ni(PyrCO)₂(H₂O)₂], with only minor amounts of the fac-Na[Ni(PyrCO)₃] tris-cyanoximate. Two other complexes, dimeric [Ni₂(PyrCO)₄(H₂O)₂]·2C₃H₇OH and tris-cyanoximate [Ni{HPyrCO}(PyrCO)₂]·2CH₃CN, contained outer-sphere solvent molecules of crystallization and were obtained as the result of direct interaction of starting compounds in narrow tubes. All isolated complexes were characterized using IR, solid-state UV–visible spectroscopy, TG/DSC analysis, and X-ray crystallography. Data showed the formation of five-membered chelate rings in all structures and adoption of the trans-geometry of cyanoxime in all crystallohydrate complexes. Heating of the RED, GREEN, and VIOLET crystallohydrates led to irreversible dehydration and the formation of an anhydrous brown complex, [Ni(PyrCO)₂]. Variable temperature magnetochemical studies of RED trihydrate confirmed a lack of interactions between isolated Ni(II) centers, while there was an antiferromagnetic interaction between metal ions in the linear chain in the polymeric anhydrous compound. Full line shape analysis of solid-state electronic spectra allowed calculation of the Racah Repulsion Parameter (B) and Nephelauxetic Constant (β). In three crystallohydrates, there were six-coordinated high-spin Ni²⁺ complexes with different degrees of rhombic (with axial elongation) distortions and, therefore, ligands’ crystal field strength. The final product of the thermal decomposition of all complexes under inert gas protection was metallic Ni sponge.

Polarity-assisting pseudohalide-controlled self-assembly of coordination polymers (CPs) is of immense significance for structural tunability and is quite necessary for exploration of the links between structure and properties. Herein, we have synthesized two polarity-assisting pseudohalide-controlled CPs, CPCd-1 and CPCd-2 ({[(Cd₂(L1)₃(NCS)₄].CHCl₃.CH₃CN}_n and {[Cd(L1)₂(N(CN)₂)₂].CH₃CN}_n) using newly developed heteroaldazine-based ligand, L1 (L1 = 1-(Z-(Z-(quinolin-4-ylmethylene) hydrazono) methyl) naphthalen-2-ol) at room temperature and systematically characterized through single-crystal X-ray diffraction (SC-XRD) methodology. Interestingly, strong and continuous π···π intermolecular interactions influence both CPs to ensure high luminescence properties in the solvent medium and in the solid phase. Further, these luminous CPs have been utilized for discriminating recognition of the lethal explosive 2,4,6-trinitrophenol (TNP). Notably, CPCd-2 shows a lower detection limit (193 ppb) toward TNP detection than CPCd-1 (the detection limit is 401 ppb), which is also confirmed by the theoretical scenario. In addition, the sensing mechanism is established via PET-ICT-π···π interaction pathways. Both CPs have numerous practical applications and have been ascertained as innovative ones in environmental domains. This type of pseudohalide-controlled CPs with quinoline-napthaldehyde heteroaldazine-based moieties is scanty in the literature that can detect TNP entirely from the aqueous phase.

In this investigation, potential host compounds N,N′-bis(9-phenyl-9-xanthenyl)propane-1,3-diamine (H1) and N,N′-bis(9-phenyl-9-xanthenyl)butane-1,4-diamine (H2) were crystallized from pure single solvents and mixtures of guests comprising xylenes (oXy, mXy, and pXy) and ethylbenzene (EB). Although H1 successfully enclathrated oXy in the single solvent experiment, this host compound was not able to extract oXy when presented with various mixtures of these guest compounds, and only the guest-free host compound was ultimately recovered from these crystallization experiments. H2, on the other hand, successfully included both oXy and pXy. Thermal experiments on H2·pXy and H2·1.5(oXy) showed that the former complex was more stable than the latter. Single-crystal X-ray diffraction (SCXRD) experiments were employed to analyze the conformations of both host molecules when guest-free and in the presence of the guest species. Experiments involving equimolar binary guest mixtures and H2 revealed that this host compound was selective for oXy whenever it was present. Furthermore, from experiments employing H2 and pXy/mXy (40:60, 50:50, and 60:40 mol %) binary mixtures, remarkable K values (the selectivity coefficient) were calculated in favor of pXy, suggesting that host–guest chemistry strategies may be used to effectively separate these difficult-to-separate mixtures when H2 is the host compound.

N,N′-Bis(9-phenyl-9-xanthenyl)butane-1,4-diamineenclathrates its preferred xylene guest species, o-xylene, in multidirectional channels, facilitating facile guest release in thermoanalytical experiments

The solution growth method is an economical and environmentally friendly approach to producing aluminum nitride (AlN) single crystals. However, the fluxes used in the solution growth method have low nitrogen solubility, which limits the growth rate of AlN. In this study, as part of the development of a solution growth method for AlN using Fe–Cr fluxes with high nitrogen solubility, experiments were conducted using type 430 ferritic stainless steel, which is composed mainly of Fe–Cr, as the flux. Through a series of experiments, we report the results of the optimization of various experimental growth parameters (AlN polarity, cooling rate, and growth temperature). Furthermore, a growth mechanism based on the Al:N ratio in the flux is proposed, introducing the concept of effective nitrogen content to explain how the growth temperature affects the AlN growth rate using Fe–Cr flux.

A novel solution growth method for AlN single crystals using type 430 ferritic stainless steel flux was investigated. The growth conditions were optimized, and the growth mechanism was proposed.

Identification of the same and similar crystal structures assists in searching for duplicate materials data and discovering prototype structures. Although several structure identification methods exist, their requirements for the input information limit their ability to accurately and automatically process structures within big materials databases and especially distinguish disordered ion conductor structures due to the site occupancy uncertainty of migration ions. Here, we introduce an automated crystal structure identification method called EMFDTW, in which a set of eigen-subspace modular functions (EMFs) is derived from a distance matrix incorporating site type identifiers, and then the similarity between them is measured through dynamic time warping (DTW). In this way, not only the conventional spatial sites in the crystal structure but also the atomic attributes (type, occupancy, oxidation state, magnetic moment, etc.) on the sites can be considered as the comparative features. Furthermore, by conducting a skeleton similarity analysis on 113,586 crystal structures sourced from the crystallography open database and the inorganic crystal structure database, we establish a database of 17,340 skeleton prototypes, which paves the way for searching potential ionic conductors. Our work provides an easy-to-use tool to analyze complex crystal structures, providing new insights for the discovery and design of new materials.

Cocrystallization has emerged as a promising strategy to obtain new solid forms of a given compound with tailored properties. In this study, a green and efficient slurry method was proposed for cocrystal synthesis using deep eutectic solvents (DESs), a new generation of green solvents, as both the solvent and reactant (i.e., cocrystal coformer). The method was subjected to cocrystal screening of carbamazepine in a series of choline chloride (ChCl) DESs and compared with the slurry method in organic solvents. The results indicate that as the cocrystal formation by a slurry method in DESs is similar to the solvate formation in organic solvents, it can overcome the issues of traditional cocrystallization in organic solvents, such as individual crystallization caused by solubility differences and the formation of unwanted solvates, thereby improving the screening efficiency of cocrystals. Further, a DES of ChCl and urea was used for cocrystal screening for 30 compounds, and all 30 cocrystals with urea were successfully synthesized after the reaction temperature and water contents of DES were adjusted, further confirming the applicability of the slurry method to various compounds. Finally, the artificial bee colony algorithm, one method of artificial intelligence, was adopted to search for low-energy stable structures of the cocrystal precursors in ChCl-urea DESs. Such given structures combined with the hydrogen bond analysis by the Atoms in Molecules theory indicated that the strong interactions between the drug and ChCl could restrain its cocrystal formation with urea. In conclusion, the slurry method based on DESs proposed in this study can overcome the obstacles of the slurry method in organic solvents, which is a green, efficient, and promising alternative method for cocrystal synthesis.

Engineering the Cd(II) coordination sphere with a terpyridine-pincer ligand and tuning the cyclotriphosphazene-fuctionalized multicarboxylates (H₄L1, H₄L2) produced one-dimensionally oriented self-assemblies, namely, [{Cd₂(trp)₂(L1)}]·DMF·3H₂O (PCP-1) and [{Cd₂(trp)₂(L2)}]·2DMF·H₂O (PCP-2). The solid-state structures of PCP-1 and PCP-2 were characterized by Fourier-transform infrared spectroscopy (FTIR), single-crystal and powder X-ray diffractions (SC and PXRD), thermal analyses (TGA), scanning electron microscopy-energy dispersive X-ray (SEM-EDX) analysis, and ultraviolet–visible diffuse reflectance measurements (UV-DRS) analysis. Both coordination polymers demonstrated efficient photocatalytic performance in the degradation of four organic dyes, namely, methylene blue (MB), methyl orange (MO), rhodamine B (RhB), and reactive orange 16 (RO16) under UVA light irradiation. Terpyridine aromatic rings exhibit strong π–π interactions (d(π···π) < 3.8 Å) that influence the formation of three-dimensional (3D) supramolecular network of PCP-1 and PCP-2 and thus can improve photocatalytic efficiency. Additionally, a plausible photocatalytic mechanism has been proposed through trapping experiments of active species to enhance our understanding of the photocatalytic degradation of dyes. Notably, the photocatalytic degradation activities of PCP-1 and PCP-2 are remarkably efficient in the degradation of MB with a rate of 96 and 91%, respectively, at 20 ppm dye concentration and 300 mg/L photocatalyst concentration. Also, PCP-1 and PCP-2 displayed high emission in the solid state. These findings contribute to understanding the potential of the cyclophosphazene-based coordination polymers in environmental remediation.

Rutin is a natural compound that is widely distributed in various plants. Increasing lines of evidence have proved that rutin has a beneficial effect on cardiovascular health, oxidative stress, and blood glucose control. However, the application of rutin is limited due to its poor solubility and low oral bioavailability. To improve the bioavailability of rutin, two cocrystals of rutin with l-proline and d-proline were prepared successfully, and multiple characterization methods were utilized to study the physicochemical properties of rutin and its cocrystals. The powder dissolution in vitro and the pharmacokinetic behavior in vivo were also evaluated. The results indicated that Rut-l-Pro exhibited a significantly improved solubility, and the oral bioavailability also had great improvement; the AUC_0–10h of Rut-l-Pro was 5.6-fold that of rutin, and C_max was 3.8 times. As a result of the improvement of rutin bioavailability, Rut-l-Pro performed better blood glucose control and cardioprotective activities.

Highly stable cobalt nanoparticle-decorated ruthenium diselenide nanorods were grown on carbon paper, resulting in the Co-RuSe₂/C structure which was directly utilized as a catalyst for the hydrogen evolution reaction (HER) in an alkaline medium. A reactive chemical vapor deposition (CVD) process with a low temperature, low pressure, and a short reaction time was employed to synthesize the Co-RuSe₂/C catalyst. Structural analysis via high-resolution transmission electron microscopy (HRTEM) and elemental distribution using scanning transmission electron microscopy energy-dispersive X-ray spectroscopy (STEM-EDS) confirmed the uniform distribution of cobalt nanoparticles (Co NPs) on densely grown RuSe₂ nanorods (NRs). Surface studies using X-ray photoelectron spectroscopy (XPS) revealed the presence of electron-deficient Ru and Se species indicating successful surface electronic structure modification of the Co-RuSe₂/C structure. Furthermore, the HER performance of the Co-RuSe₂/C catalysts was evaluated in 1 M KOH, demonstrating an excellent performance sustained over an extended period.

The stability of mixed-valence V₆O₁₃ at high pressures and high temperatures is studied experimentally in multianvil presses both ex situ and in situ using synchrotron energy-dispersive powder diffraction. V₆O₁₃ starts to amorphize and decomposes above 18.5 GPa at room temperature. It transforms to rutile-related V_0.92O₂ above 500 K in the pressure range up to about 15–17.5 GPa. The crystal structure of this new phase (C12/m1, Z = 4) was determined from laboratory single-crystal and powder X-ray diffraction data measured on single crystals grown at 10 GPa and 1373 K. The characteristic feature is the presence of two zigzag V–V chains. One of them has equidistant V atoms, while the other is with short and long V–V distances. In the average-ordered structure (P2/m, Z = 2), both V–V chains are linear and equidistant. The M2 polymorph of VO₂ is considered to be the ordered (though distorted) variant of V_0.92O₂. The experiments are complemented by density functional theory calculations and global explorations of the energy landscape of V₆O₁₃ and V_0.92O₂ compounds at high pressures using a multimethodological approach to construct and predict feasible structures.