Crystal Growth & Design最新文献

This study investigated the role of various polymers as precipitation inhibitors in solutions of flufenamic acid (FFA) and its cocrystals with theophylline (FFA-TP) and nicotinamide (FFA-NIC). Through a combination of NMR spectroscopy, molecular dynamics simulations, and nucleation studies using Crystal16, we evaluated the effects of polyethylene glycol (PEG), polyvinylpyrrolidone-vinyl acetate (PVP-VA), and soluplus (SOL), both individually and in combinations, on the nucleation, diffusion, and self-association of FFA molecules in solution. ¹H NMR and DOSY measurements revealed that while PEG was highly effective in reducing molecular mobility, thus significantly delaying nucleation, PVP-VA facilitated nucleation by enhancing FFA diffusion and aggregation. SOL provided a balance, enhancing molecular mobility but maintaining a delayed nucleation effect, likely due to micellar encapsulation, as evidenced by line broadening in ¹H NMR. Combination systems such as PVP-VA-PEG and PVP-VA-SOL showed synergistic effects, with PVP-VA-SOL proving particularly effective in inhibiting FFA nucleation across all systems. Molecular dynamics simulations supported these findings by highlighting changes in intermolecular interactions and aggregation tendencies in the presence of each polymer. This comprehensive analysis suggested that selecting appropriate polymeric excipients, or combinations thereof, can finely tune the nucleation behaviors of drug solutions, offering a strategic approach to optimizing the stability of supersaturated drug solutions.

This study investigated the role of various polymers as precipitation inhibitors in solutions of flufenamic acid (FFA) and its cocrystals with theophylline (FFA–TP) and nicotinamide (FFA–NIC). Through a combination of NMR spectroscopy, molecular dynamics simulations, and nucleation studies using Crystal16, we evaluated the effects of polyethylene glycol (PEG), polyvinylpyrrolidone–vinyl acetate (PVP–VA), and soluplus (SOL), both individually and in combinations, on the nucleation, diffusion, and self-association of FFA molecules in solution. ¹H NMR and DOSY measurements revealed that while PEG was highly effective in reducing molecular mobility, thus significantly delaying nucleation, PVP–VA facilitated nucleation by enhancing FFA diffusion and aggregation. SOL provided a balance, enhancing molecular mobility but maintaining a delayed nucleation effect, likely due to micellar encapsulation, as evidenced by line broadening in ¹H NMR. Combination systems such as PVP–VA–PEG and PVP–VA–SOL showed synergistic effects, with PVP–VA–SOL proving particularly effective in inhibiting FFA nucleation across all systems. Molecular dynamics simulations supported these findings by highlighting changes in intermolecular interactions and aggregation tendencies in the presence of each polymer. This comprehensive analysis suggested that selecting appropriate polymeric excipients, or combinations thereof, can finely tune the nucleation behaviors of drug solutions, offering a strategic approach to optimizing the stability of supersaturated drug solutions.

This study investigates the role of polymers in modulating precipitation of flufenamic acid (FFA) from cocrystal solutions using NMR, molecular dynamics, and nucleation studies. Results reveal how polymer interactions influence dissolution, diffusion, and nucleation, aiding in the rational design of cocrystal formulations to enhance drug stability and bioavailability.

Preorganization of supramolecular network structures by designing building block molecules from aspects of supramolecular synthons and tectons is fundamental for developing porous organic materials. Benzene derivatives possessing 4-carboxyphenyl groups are suitable systems to explore the relationship between the symmetry of tectons and the resultant supramolecular network structures because of directional hydrogen bonding of the carboxy groups. Herein, supramolecular network structures composed of C_s-symmetric 1,2,4-tris(4-carboxyphenyl)benzene and its analogues with pyridine and isoquinoline cores are reported. These tritopic carboxylic acids form a ladder-shaped motif instead of a brick-type network motif via intermolecular hydrogen bonding. Their crystal structures and thermal behaviors are thoroughly investigated, revealing that they showed multistep structural transformations upon release of the solvent molecules included in their voids. The behaviors strongly depend on the cores. These results can contribute to the field of reticular chemistry from aspects of molecular symmetry and the resultant network topology.

AlGaN-based light-emitting diodes (LEDs) operating in the deep-ultraviolet (DUV) spectral range have exhibited a promising future in physical sterilization. However, the low Mg doping efficiency hinders the further development of high-performance AlGaN-based DUV LEDs. Herein, we demonstrate the performance of 279 nm AlGaN-based DUV LEDs beyond the state-of-the-art by exploiting the periodic Mg doping strategy. In contrast to continuous doping, periodic doping can improve the crystalline quality and the Mg distribution in the p-Al_0.66Ga_0.34N layer, thereby achieving higher doping efficiency of Mg dopants with lower doping concentration. As a result, after forming the periodic-doping electron-blocking layer (EBL), the light output power (LOP) of the DUV LED is improved by 92.4% at 300 mA in contrast to its referred counterpart with continuous-doping EBL. Our work is able to provide a new horizon in the development of highly efficient AlGaN-based DUV emitters.

Controlling crystal morphology is important in many areas of science including drug manufacturing, single-crystal X-ray diffraction, and high explosive production. To understand the effects of solvent choice on the growth of the common explosive initiator PETN, we employed temperature-controlled crystallization in four solvents and two mixed solvents to observe the resulting crystal morphology. We further investigated the morphologies using established shape prediction models─the modified attachment energy model and the occupancy attachment energy model─as well as our modified surface energy model, presented here. We found that none of these energetic models accurately reproduce the observed morphologies, suggesting that predictions based solely on energetics are not always reliable and that there is a need to also consider kinetic and/or entropic effects. Lastly, we examined the effects of crystal morphology on subshock sensitivity through both traditional drop weight impact testing and the new VIPIR test. The confounding results highlight the need to consider multiple testing options when evaluating the effects of morphology.

The difficulty in developing new trinitromethyl energetic materials stems from the need to balance the opposing properties of high energy and low sensitivity. This study reports new synthetic compounds based on the combination of trinitromethyl groups and a fused-ring system. In this work, three novel fused-ring compounds, 7-amino-3-nitro-2-(trinitromethyl)pyrazolo[1,5-a]pyrimidine-6-carboxylic acid (3), 3-nitro-6-(1H-tetrazol-5-yl)-2-(trinitromethyl)pyrazolo[1,5-a]pyrimidin-7-amine (5), and 3,6-dinitro-2-(trinitromethyl)pyrazolo[1,5-a]pyrimidin-7-amine (7), were all synthesized through cyclization and nitration reaction. Compounds 3 (V_D = 8549 m·s^–1, ρ = 1.79 g·cm^–3) and 5 (V_D = 8520 m·s^–1, ρ = 1.80 g·cm^–3) both demonstrate high density and detonation velocities that closely resembles that of RDX (V_D = 8795 m·s^–1, ρ = 1.80 g·cm^–3). Remarkably, compound 7 featured with an ortho amino-nitro group exhibits a higher density of 1.82 g·cm^–3 and more excellent detonation performance (V_D = 8867 m·s^–1, P = 35.1 GPa) than RDX (V_D = 8795 m·s^–1, P = 34.9 GPa). Compounds 5 and 7 both exhibit better thermal stability (T_d (5) = 155 °C and T_d (7) = 178 °C) compared with those of the already synthesized trinitromethyl energetic compounds. In addition, compounds 5 (IS = 16 J, FS = 168 N) and 7 (IS = 14 J, FS = 144 N) both exhibit sensitivity lower than that of RDX (IS = 7.4 J, FS = 120 N). The above results suggest the great application potentials of compound 7 as a high-energy and low-sensitivity energetic material.

The construction of functional cyanometallate clusters connected by secondary bridges is a highly sought-after area of research in chemistry and materials science. Our investigation has led to the discovery of three novel compounds, {[(Tp*)Fe(CN)₃Co(bpy)]₂(μ-CA)·4MeOH}_n (1), {[(Tp*^Me)Fe(CN)₃Co(dpa)]₂(μ-CA)}_n (2), and {[(Tp*^Me)Fe(CN)₃Co(bpy)]₂(μ-dhbq)}_n (3) (Tp* = hydrotris(3,5-dimethylpyrazolyl)borate, Tp*^Me = hydrotris(3,4,5-trimethylpyrazolyl)borate, H₂CA = 2,5-dichloro-3,6-dihydroxy-2,5-cyclohexadiene-1,4-dione, dhbq = 2,5-dihydroxy-1,4-benzoquinone, bpy = 2,2′-bipyridyl, and dpa = 2,2′-dipyridylamine). These compounds were synthesized via a self-assembly reaction of the [(Tp^R)Fe^III(CN)₃]⁻ building block, Co(II) salts, and chelating ligands of bpy or dpa, followed by addition of benzoquinone dianions. X-ray crystallographic analyses revealed that 1–3 exhibited similar structures, where cyanide-bridged [Fe₂Co₂] squares are connected by benzoquinones to form a one-dimensional chain. Magnetic studies demonstrated a ferromagnetic interaction between the cyanide-bridged Fe and Co ions but an antiferromagnetic interaction between the benzoquinone-bridged Co–Co pairs. Notably, compounds 2 and 3 displayed metamagnetic behaviors with antiferromagnetic orderings below 4 K.

Inhibiting the crystallization of cholesterol monohydrate (ChM) crystals is crucial for preventing the progression of high cholesterol symptoms into gallstones and atherosclerosis. In recent years, cholesterol-lowering functional substances containing linoleic acid (LA) or its analogue ethyl linoleate (EL) have emerged as promising alternatives to pharmaceuticals, offering similar functions without the associated side effects. In this study, the impact of LA or EL on the crystallization of ChM crystals was investigated. The results demonstrated that both additives effectively prolonged the nucleation induction time of ChM crystals and therefore inhibited the nucleation of ChM crystals. However, the nucleation inhibition efficiency of LA on ChM nucleation was higher than that of EL. This difference is due to the stronger interaction of LA containing carboxyl groups with the cholesterol molecules in the solution than that of EL containing ester groups. Furthermore, the growth kinetics of ChM crystals were revealed by an in situ optical microscope. The results illustrated that the growth rate of ChM crystals along [010] and [100] directions decreased in the presence of LA or EL. Along the [010] direction, the growth inhibition efficiency of LA was always higher than that of EL. This is because the binding between LA with carboxyl groups and the hydroxyl groups exposed on the (010) face of the ChM crystals was stronger than those of ester groups in EL. Meanwhile, along the [100] direction, the growth inhibition efficiency of EL is always higher than that of LA. This is because EL binds to the exposed methyl groups on the (100) face of the ChM crystals primarily through van der Waals forces and other noncovalent interactions, enhancing the growth inhibition efficiency on the (100) face of ChM crystals. These binding modes have been confirmed by molecular simulation. This study not only demonstrated the importance of the molecular structure of additives in modulating ChM crystallization behavior but also provided insights that develop novel therapeutic strategies for preventing atherosclerosis, cardiovascular diseases, and cholesterol gallstone formation.

Long-persistent luminescence (LPL) materials have been widely applied and investigated in the fields of night-safe, biofluorescent labeling and optical anticounterfeiting due to the unique properties of delayed luminescence. However, the development of a high efficiency, low cost, high precision spectral tunable deep-red LPL phosphor is still a problem to be solved. In this work, a deep-red LPL phosphor Zn_2.1Mg_0.9–xGa_xGe_xTa_2–xO₈:0.003Cr³⁺ was produced, which with four crystal structure sites can be replaced by Cr³⁺, and its luminescence properties are regulated by cation regulation engineering. The location allocation of the four luminescence centers was discussed by using TL and fluorescence attenuation curves. The introduction of [Ga³⁺–Ge⁴⁺] produces traps, resulting in LPL. With the adjustment of [Ga³⁺–Ge⁴⁺] concentration, the LPL property was increased. The brightness of the LPL has been improved, and LPL times can continue to 2 h. The mechanism of LPL and the reason for short LPL time are further analyzed by establishing the mechanism model of LPL. The application performance of phosphor can be improved by introducing [Ga³⁺–Ge⁴⁺]. A set of anticounterfeiting application models was designed based on the different decay rates of LPL. This proven ion pair substitution strategy can be used to adjust trap distribution, improve LPL performance, and develop novel phosphors with practical optical application potential.

The influence of halogen-atom substitution for a dimethyl isophthalate compound on the polymorphic behavior and isostructurality property was explored in this paper. Sublimation was demonstrated to exhibit remarkable advantages. Specifically, two polymorphs (Form I and Form II) of dimethyl 5-bromoisophthalate and two polymorphs (Form A and Form B) of dimethyl 5-iodoisophthalate were discovered for the first time. Moreover, the corresponding single crystals suitable for crystal structure determination were also successfully harvested within a few hours. More interestingly, the crystal packing similarities between the stable Form II and metastable Form A were established with the evaluation of quantitative analysis tools. The success in achieving the regulation of luminescence emission with the changes of crystal packing patterns, molecular conformations, and interactions via halogen substitution will provide some inspiration for the development of novel flexible optical solid-state systems in the future.