Crystal Growth & Design最新文献

Development and production of novel high-performing nitrogen-rich energetic compounds with a safe and environmentally friendly nature are significant in the pursuit of new-generation green energetic materials. Despite the growing interest in energetic cations in recent years, fused heterocyclic energetic cations have rarely been reported. In the following study, a series of energetic materials comprising purine compounds and oxidants were prepared using a significant noncovalent self-assembly method. Elemental analysis, mass spectrometry (MS), IR spectroscopy, and differential scanning calorimetry (DSC) were used to characterize these synthesized compounds thoroughly. The structures of supramolecules (1–4) were further verified by employing the single-crystal X-ray diffraction technique, and standard BAM methods were used to determine the sensitivities. Furthermore, theoretical calculations and experimental data were used to elucidate the relationship between the structure and properties. Comprising several benefits such as simple and facile preparation, high yield, high density, superior thermostability, insensitive nature, and good detonation properties, the synthesized compounds are regarded as competitive green energetic materials.

A methodology for the prediction of face-specific relative dissolution rates for single-faceted crystals accounting for inequivalent wetting by the solvent is presented. This method is an extended form of a recent binding energy model developed by the authors (Najib et al., Cryst. Growth & Des. 2021, 21(3), 1482–1495) for predicting the face-specific dissolution rates for single-faceted crystals from the solid-state intermolecular binding energies in a vacuum. The principal modification is that the equivalent wetting of the crystal surfaces is no longer assumed, since interactions between the crystal surfaces and the solution-state molecules are incorporated. These surface interactions have been investigated by using a grid-based systematic search method. The face-specific dissolution rates predicted by the extended binding energy model for ibuprofen in a 95% v/v ethanol–water solution and furosemide in an aqueous medium have been validated against the published experimental results and are in excellent agreement. This model is a step forward toward accurate predictions of the relative face-specific dissolution rates for a wide variety of faceted crystals in any dissolution medium.

A methodology is presented for predicting face-specific relative dissolution rates of single faceted crystals accounting for the inequivalent wetting by solvent. The predictions are validated against dissolution data for ibuprofen in ethanol−water and furosemide in aqueous medium with excellent agreement. It provides a step forward toward accurate predictions of dissolution rates for a variety of faceted crystals in different dissolution medium

A Couette cell flow device was designed, and an experimental procedure was developed to enable a quantitative study of the effects of fluid shear on secondary nucleation using a fixed seed crystal under controlled supersaturation, temperature, and flow conditions. This approach excludes mechanical impact, which is often considered to be the principal source of secondary nucleation, for example, through crystal attrition. We found that secondary nucleation rates of α-glycine in aqueous solutions induced by fluid shear were very significant and about 6 orders of magnitude higher than primary nucleation rates at the same conditions. Secondary nucleation rates per seed crystal were found to be about 1 order of magnitude lower compared with the magnetically stirred vials investigated previously, where a single seed crystal was freely moving, and thus, its mechanical impacts could not be ruled out. Computational fluid dynamics was used to calculate the wall shear stress along the surface of fixed seed crystals placed in the Couette cell gap at rotation rates between 100 and 600 rpm investigated here. This approach allows relating the secondary nucleation rate to the wall shear stress so that quantitative models can be developed to capture the effects of fluid shear on secondary nucleation kinetics. Such models will then facilitate scale-up and transfer of secondary nucleation kinetics between various equipment used in industrial crystallization processes.

The table of contents graphic shows the nucleation rates recorded in small, magnetically agitated vials compared with those from the Couette flow cell in which a seed was held in place and exposed to laminar shear. Secondary nucleation rates are much higher than primary nucleation rates in both cases, which indicates the significance of secondary nucleation induced by fluid shear.

Disorder is a common feature of molecular crystals that complicates determination of structures and can potentially affect electric and mechanical properties. Suppression of disorder is observed in otherwise severely disordered benzamide and thiobenzamide crystals by substituting hydrogen with fluorine in the ortho-position of the phenyl ring. Fluorine occupancies of 20–30% are sufficient to suppress disorder without changing the packing motif. Crystal structure prediction calculations reveal a much denser lattice energy landscape for benzamide compared to 2-fluorobenzamide, suggesting that fluorine substitution makes disorder less likely.

Disorder is a common feature of molecular crystals that complicates characterization and affects properties. We demonstrate suppression of disorder in otherwise severely disordered benzamide and thiobenzamide crystals without changing the packing motif by substituting hydrogen with fluorine in the ortho-position of the phenyl ring. Crystal structure prediction calculations help rationalize this observation.

The presence of magnesium and phosphorus in calcium carbonate-based biominerals is increasingly found. Both elements play a significant role in the biomineralization process of amorphous calcium carbonate (ACC). While extensive research has focused on the effects of their compositions, less attention is given to the influence of precursor solution concentrations, which is essential for unraveling the crystallization mechanism. Herein, taking amorphous magnesium calcium carbonate phosphate (MgACCP) (molar ratio of Ca²⁺/Mg²⁺/CO₃^2–/PO₄^3– fixed at 4:1:4:1) as the example, we report that the amorphous stability highly depends on the precursor solution concentrations. Moderate concentrations (0.04–0.6 M) lead to faster crystallization within a week and the production of bundled nanofibers. In more diluted solutions (0.01 M), the accumulation of Ca²⁺ and CO₃^2– at the boundaries of colloidal nanobubbles leads to hydration, which stabilizes ACC. Conversely, in more concentrated solutions, a greater amount of Mg²⁺ in the homogeneous solution binds with water to preserve the amorphous state of MgACCP. The hydration level is determined to be a critical factor in determining the crystallization rate. These findings offer new insights into the crystallization mechanism and morphology control of bioceramics.

Reported are the synthesis, structural characterization, and luminescence properties of 11 novel UO₂²⁺/Ag⁺ heterometallic complexes. Halogenated benzoic acids (2,6-dihalobenzoic acid (halo = F, Br), 3,5-dichlorobenzoic acid, and 3-halobenzoic acid (halo = Br, I)) and N-donor polycyclic ligands (2,2′-bipyridine, 2,2’;6′,2″-terpyridine, 1,10-phenanthroline, 2,2′-bipyrimidine) were employed to synthesize a set of compounds and induce structural diversity. The primary mode of coordination with the uranyl cation is hexagonal bipyramidal monomeric units with three halobenzoate ligands in the equatorial plane, though 1-D chains with pentagonal bipyramidal uranyl centers also form. The Ag⁺ cations coordinate preferentially to the N-donor ligands and serve as counter-cations for the anionic uranyl motifs. The soft ligand character of the N-donor molecules is found to be a requirement for the inclusion of the Ag⁺ cation into the structures. Anionic uranyl units and cationic silver units assemble via noncovalent interactions between π systems on adjacent rings and between halogens (when Br and I are present). Solid-state emission spectra display the usual uranyl band with superimposed vibronic fine structure, except for that of compound 1, which shows emission from the 2,2′-bipyridine center. This family of compounds represents a substantial contribution to the already rich library of UO₂²⁺/Ag⁺ compounds, and the synthetic parameters discussed within reveal a platform for the design of new heterometallic uranyl-containing materials.

Crystals are integral to a variety of industrial applications, such as the development of pharmaceuticals and advancements in material science. To anticipate crystal behavior and pinpoint effective crystallization techniques, a thorough investigation of crystal structures, properties, and the associated processes is essential. However, conventional methods like experimental procedures and quantum mechanics calculations, while crucial, can be expensive and time-consuming. In response, machine learning has risen as an effective alternative, complementing the traditional approaches based on quantum mechanics and classical force fields. In the recent years, the deployment of machine learning in the realm of crystallization has yielded notable progress. This review offers a concise overview of the application of machine learning techniques in crystallization, focusing on the past five years. Our analysis of the literature indicates that machine learning has accelerated the prediction of crystal structures by streamlining the generation and evaluation of structures. Additionally, it has facilitated the prediction of key crystal properties such as solubility, melting point, and habit. The review further explores the role of machine learning in refining the control and optimization of crystallization processes, highlighting the restrictions of conventional algorithms and sensing technologies. The advantages of end-to-end processing for enhancing the accuracy of predictions and the combination of data-driven with mechanism-based models for robustness are also considered. In summary, this review provides insights into the current state of machine learning in the field of intelligent crystallization and suggests pathways for future research and development.

In this study, we examine the experimental and theoretical capabilities of two perhalogenated anilines, 2,3,5,6-tetrafluoro-4-bromoaniline (btfa) and 2,3,5,6-tetrafluoro-4-iodoaniline (itfa) as hydrogen and halogen bond donors. A series of 11 cocrystals derived from the two anilines and selected ditopic nitrogen-containing acceptors (4,4′-bipyridine, 1,2-bis(4-pyridyl)ethane, and 1,4-diazabicyclo[2.2.2]octane) in 1:1 and 2:1 stoichiometries were prepared by liquid-assisted grinding and crystallization from solution. Crystallographic analysis revealed bifunctional donor properties in both anilines. The dominant supramolecular interaction in four cocrystals of btfa is the N–H···N_acceptor hydrogen bond between btfa and acceptor molecules, while in the one remaining cocrystal, donor and acceptor molecules are connected via the N–H···N_acceptor hydrogen bond and the Br···N_acceptor halogen bond. In two cocrystals of itfa, the dominant supramolecular interaction is the I···N_acceptor halogen bond between itfa and acceptor molecules, while in the remaining four cocrystals, donor and acceptor molecules are additionally connected by the N–H···N_acceptor hydrogen bond. Periodic density-functional theory (DFT) calculations have been conducted to assess the formation energies of these cocrystals and the strengths of the established halogen and hydrogen bonds. Molecular DFT calculations on btfa and itfa indicate that the differences in electrostatic potential between the competing sites on the molecules are 261.6 and 157.0 kJ mol^–1 e^–1, respectively. The findings suggest that itfa, with a smaller electrostatic potential difference between donor sites, is more predisposed to act as a bifunctional donor.

The experimental and theoretical capability of two perhalogenated anilines, 2,3,5,6-tetrafluoro-4-bromoaniline and 2,3,5,6-tetrafluoro-4-iodoaniline, as hydrogen and halogen bond donors have been explored by cocrystallization with 4,4′-bipyridine, 1,2-bis(4-pyridyl)ethane, and 1,4-diazabicyclo[2.2.2]octane.

Mono- and bis-carbonyl hypoiodites incorporating the tertiary amines quinuclidine (1a–e) or 1,4-diazabicyclo[2.2.2]octane (DABCO; 2a, 2b, and 2e), respectively, have been synthesized and represent the first examples of hypoiodites stabilized by alkyl amines rather than aromatic Lewis bases (e.g., pyridine derivatives). These highly reactive complexes have been characterized in the solid state by SCXRD and DFT calculations. The DABCO hypoiodite derivatives are rare examples of ditopic bis(O–I–N) complexes and were found to display unexpected bonding parameters relative to iodine(I) complexes in which the DABCO is coordinating in a monotopic manner.

Mono- and bis-carbonyl hypoiodites incorporating the tertiary amines quinuclidine or 1,4-diazabicyclo[2.2.2]octane have been synthesized and represent the first examples of hypoiodites stabilized by alkyl amines rather than aromatic Lewis bases.

Coordination polymers serve as an important platform to promote highly selective solid-state reactions between organic struts. A new class of amide-containing cyclobutane molecules has been synthesized using a [2 + 2] photodimerization reaction in coordination polymers (CPs) of rigid and linear diene 3,3′-(1,4-phenylene)bis(N-(3-pyridyl)acrylamide), 4PMA, with rigid as well as flexible dicarboxylates as coligands. Four Co(II) CPs studied here produce 2D layers with rhomboidal grids (isophthalate (CP-1) and p-carboxy cinnamate (CP-2)), while p-phenylene acrylate (CP-3) yields a 3D framework with cds topology and p-phenylene diacetate forms 2D layers with a bimetallic secondary building unit (SBU). The [2 + 2] cycloaddition reaction upon exposure to 365 nm UV light on the methanol solvate of 4PMA remained elusive despite a favorable polymeric alignment in its crystal structure. Single crystals of CPs upon irradiation resulted in photodimerization; however, the crystal structure suggests polymerization (CP-1 and CP-2) or no reaction (CP-3). This unusual behavior is attributed to deviations in geometrical parameters from the ideal, serving as the driving force behind the photodimerization reaction. Nevertheless, the 2D CP of CP-4 exhibited resilience during dimerization, leading to the formation of a 3D coordination polymer of the fsc net of CP-4P through a single-crystal-to-single-crystal structural transformation. The separated dimer product displays quenched photoluminescence and blue-shifted spectra compared with the monomer.