Crystal Growth & Design最新文献

Herein, we show how it is possible to prepare a monomer, a dimer, a trimer and a chain with cobalt(II) and the ligand nitranilato (3,6-dinitro-2,5-dihydroxy-1,4-benzoquinone dianion = C₆O₄(NO₂)₂^2– = NA^2–) by simply changing the counter-cations. Thus, we show that when we combine the ligand NA^2– with cobalt(II) in the presence of a bulky cation as PPh₄⁺, we obtain compound (PPh₄)₄[Co(NA)₃] (1), which contains the first monomeric anion of the type [Co(L)₃]^4– (L = any anilato ligand). With a smaller cation as NMe₄⁺, we obtain (NMe₄)₂[Co₂(NA)₃(H₂O)₄] (2), a rare example of anilato-containing dimer based on a transition metal (TM). With a larger cation as NPr₄⁺, we obtain a trinuclear cobalt–nitranilato complex formulated as (NPr₄)₂[Co₃(NA)₄(H₂O)₆] (3) and finally, when using the small NH₄⁺ cation, we obtain the neutral chain: [Co(NA)(H₂O)₂] (4). This work presents the synthesis and structure of these compounds and the magnetic characterization of compounds 2–4 that show the presence of very weak antiferromagnetic interactions between the cobalt centers through the anilato bridges.

The incorporation of nanoparticles into a growing crystal is rather counterintuitive due to interfacial incompatibility between the guest nanoparticles and the host crystals. Furthermore, achieving precise control over the spatial distribution of these nanoparticles within the host crystals presents a significant challenge. In this study, we judiciously synthesize three types of well-defined copolymer nanoparticles, each with different steric stabilizers─poly(methacrylic acid), poly(3-sulfopropyl methacrylate potassium), or poly(methacrylic acid-stat-3-sulfopropyl methacrylate potassium)─via polymerization-induced self-assembly. Such nanoparticles are then used as model additives in the crystallization of calcite under varying initial calcium ion concentrations. Remarkably, systematic investigations reveal that the spatial distribution of these copolymer nanoparticles within a calcite single crystal is governed by their surface chemistry and the initial calcium ion concentration. The underlying mechanisms are proposed to rationalize these intriguing phenomena of spatially tunable nanoparticle incorporation. This work provides important “design rules” for rationally regulating the spatial incorporation of guest nanoparticles into host crystals, thereby offering a straightforward and effective approach for making crystalline nanocomposites with controllable internal compositions and structures.

With the rapid development of quantum information science, there has been a growing focus on the research and development of high-performance quantum entanglement sources. Based on the principle of quasi-phase match (QPM), periodically poled KTiOPO₄ (PPKTP) is widely utilized for generating entangled photon pairs through spontaneous parametric down-conversion (SPDC) processes. However, the mechanism of ferroelectric domain reversal in KTiOPO₄ crystals remains rarely studied and presents a significant challenge for producing high-quality PPKTP. In this study, we conducted domain reversal experiments on flux-grown KTiOPO₄ crystals with varying potassium contents. The resistivity would be changed during potassium migration under a poling electric field in KTiOPO₄ crystals with potassium vacancies. The results indicate that the potassium migration based on the potassium vacancies played a key role in controllable domain reversal of the KTiOPO₄ crystal. Without any chemical or physical treatment, we successfully prepared PPKTP with periods from 10 to 46.2 μm at room temperature and verified their nonlinear SPDC properties. Our findings suggest that the presence of potassium ion vacancies significantly influences the reversal of domain structure in the KTiOPO₄ crystal, emphasizing the importance of high-quality crystals with reduced K ion vacancies for achieving superior PPKTP quality.

Two new octanuclear lanthanide coordination complexes [Tb₈(dpim)₄(μ-OH)₈(NO₃)₈] (1) and [Tb₈(dpim)₄(μ-OD)₈(NO₃)₈] (2) were prepared using terbium(III) nitrate salt in ethanol and deuterium oxide (for only 2) and a hexadentate ligand [(2,2-dimethyl-1,3-propanediyl)bis(iminomethylene)bis(6-methoxyphenol)] (H₂dpim). The molecular structures of 1 and 2 comprise octanuclear compounds featuring eight Tb(III) ions, four dpim^2– ligands, eight OH^–/OD^– bridges, and eight nitrato ligands. One Tb(III) ion is located in the inner N₂O₂ compartment of dpim^2– and bonded to two nitrate anions. Two Tb(III) ions are located in the distorted outer O₂O₂′ compartment of the dpim^2– ligand and coordinated by a hydroxyl bridge. Three Tb(III) ions are connected through a hydroxyl group, while one Tb(III) ion is connected to an adjacent [Tb₂(dpim)]⁴⁺ derivative unit. Consequently, the structure consists of an octanuclear complex with four corner-sharing incomplete cuboidal {Tb₃O₄} cores, decorated with eight terminal nitrato, methoxy, and phenolato ligands. The structure of 2 is isomorphic to that of 1, except that it contains OD^–. Photoluminescence spectroscopy revealed that the octanuclear complexes exhibited strong luminescence in the 488–620 nm range. Complex 2, with OD^– bridging ligands, exhibited considerably higher emission than 1 because of the deuteration effect. The quantum yields of 1 and 2 were 19 and 75%, respectively. Magnetic measurements revealed that the magnetic behavior of 2 exhibited a slightly stronger contribution from the depopulation of Stark levels and antiferromagnetic couplings compared to 1.

Modulating the luminescent characteristics of solid materials via the multicomponent crystallization process to form cocrystals and hydrates poses a formidable and significant challenge. In this study, we demonstrated the aggregation-induced emission characteristics of piroxicam and synthesized four distinct cocrystals using salicylic acid, m-chlorobenzoic acid, saccharin, and 1-hydroxy-2-naphthalenecarboxylic acid as coformers. We comprehensively characterized the crystal structures and luminescent properties of these cocrystals using powder X-ray diffractometer, fluorescence microscopy, and fluorescence spectrophotometry. Moreover, the relationship between the crystal structure and fluorescence properties was established through theoretical analyses, including the calculation of intermolecular interactions, the distribution of frontier orbitals obtained based on density functional theory, and the electron density distribution derived from molecular electrostatic potential calculations. Additionally, we synthesized a novel piroxicam hydrate that exhibits a reversible fluorescence switching effect in response to acidic, basic, and thermal stimuli upon absorbing, eliminating, or replacing water molecules within the lattice, which renders it suitable for application in thermal and pH sensors, as well as information encryption. Overall, this approach offers a promising framework for precisely tuning the fluorescent properties of AIE molecules through the hydration and dehydration processes of organic crystals.

Deactivating the concentration of marine microorganisms is suitable and proper for ballast water treatment. In here, a promising strategy has been presented to create massive oxygen vacancies synergistic with metallic Bi nanoparticles on ZnWO₄ for inactivating marine bacteria in seawater, demonstrating that the paramount incorporation of metallic Bi nanoparticles and 2BZWO (Bi/ZnWO₄) samples exhibits superior photocatalytic sterilization, in which the sterilization efficiency of 2BZWO is 2.83 times that of pure ZnWO₄. The co-incorporation of metallic Bi nanoparticles and oxygen vacancies significantly enhanced the absorption of visible light and enrichment of the photogenerated electrons, promoting the separation of charge carriers. Moreover, first-principles calculations demonstrate that the coeffect of metallic Bi nanoparticles and oxygen vacancies guided the reconfiguration of the active sites and electrons flowing direction. Results from this study provide a creative strategy on controllable Bi/ZnWO₄ synthesis to manipulate the photocatalytic inactivation of marine bacteria.

Crystal growth is a key stage during the crystallization process that influences the properties of the crystal and the downstream processing, while the growth unit forms and behaviors during crystal growth have not been thoroughly understood. In this work, growth unit forms and behaviors of 7-aminocephalosporanic acid (7-ACA) during the crystal growth process, including the bulk diffusion and surface integration stages in aqueous solution, were systematically explored through experiment and molecular dynamics simulation. First, the self-association of the 7-ACA molecule into the dimer in the aqueous solution was confirmed by ultraviolet and Fourier transform infrared spectroscopies. Moreover, the exact dimer structure was mainly determined as N₇H₈···O₄═C₂₂ (1.966 Å/154°, AGG I) and N₇H₉···O₃–C₂₂ (1.477 Å/153°, AGG II) hydrogen-bonded dimers based on the MD simulation and nuclear Overhauser effect spectroscopy, acting as the growth unit in the solution. Furthermore, dependent on the mean square displacement, diffusion coefficient, surface chemistry, and interaction energy results, it was revealed that the AGG II growth unit was easier to diffuse from the bulk solution and adsorbed onto the crystal surface to promote crystal growth in comparison with AGG I. In addition, the diffusion and attachment of the growth units onto the (0 0 1) face were the most difficult, which led to the slowest growth rate and most dominant morphological face.

Polymorphism control in crystallization processes is critical for ensuring the final quality of active pharmaceutical ingredients (APIs). In the present research, the solvent-mediated phase transformation (SMPT) of paracetamol, a widely used API, from its metastable form II to the stable form I during seeded batch cooling crystallization in isopropyl alcohol/water solution is investigated. The study explores the utility of offline FT-NIR spectroscopy and an inline PAT Blaze900 probe to detect paracetamol polymorphs and monitor polymorphic changes. Key findings demonstrate that FT-NIR offers a robust offline alternative for polymorphism detection and monitoring. The PAT Blaze900 recordings, in terms of chord length counts and distributions, also provide additional information about form II SMPT and are in accordance with the FT-NIR prediction model output. The SMPT kinetics are influenced by operational parameters such as supersaturation and operational and cooling temperature. Optimization of these parameters enabled better control over the SMPT kinetics, paving the way for efficient stabilization of paracetamol metastable form II to 30 min before complete conversion to the most stable form I.

Iodate is an important class of optoelectronic functional materials, however, only a few hafnium-based iodates have been reported at present. Herein, a series of alkali metal hafnium-based iodates A₂Hf(IO₃)₆ (A = K, Rb, Cs) and isomorphic Ba₂Zn(IO₃)₆ were synthesized by the hydrothermal method. These four crystals all crystallized in the trigonal system with an R$\overline{3}$ space group. Both Hf⁴⁺ and Zn²⁺ are six-coordinated with six IO₃^– groups, forming a petal-shaped arrangement. Based on millimeter-sized crystals, their ultraviolet cutoff edges were measured as 329–347 and 288 nm, respectively. Theoretical calculation shows that they possess a large birefringence of 0.092–0.111@1064 nm. This work not only provides potential birefringent materials but also enriches the iodate system.

Molecular crystals hold potential applications in soft and flexible devices because of their periodic arrangements, flexibility to design, lightweight, and tunable supramolecular connections. Their rich polymorphism offers the additional advantage that the properties of different crystal forms can be studied for a given molecular structure. This study focuses on the directional crystallization of salicylideneaniline to control its polymorphic α and β forms. We discovered that upon directional crystallization from nonground β crystals, the metastable α form was yielded with well-aligned crystal habits. In contrast, by grinding β crystals before directional crystallization, the stable β form was surprisingly produced. These polymorphs were determined using X-ray diffraction, and their differences in photochromic behaviors have been investigated. This study confirms directional crystallization as a novel approach to polymorphic control. It provides a promising method for fabricating well-aligned, shape-specific, and desired polymorphic crystalline materials suitable for device fabrication.