CrystEngComm最新文献

Two T–X binary phase diagrams have been constructed between salicylic acid (SA) and two monotropic polymorphs of the isomer 3-hydroxybenzoic acid (3HBA). Crystalline solid solutions (CSS) were formed at all extremes of the phase diagrams. The solid-state miscibilities ranged from 0.5% up to 6% of the second component. The thermodynamically stable form I of 3HBA exhibited a higher solid state miscibility than form II of 3HBA across all investigated temperatures. The solubility changes induced by the different CSS were measured experimentally in 40 w% methanol in water at 25 °C and are presented in two ternary phase diagrams. The SA-rich CSS phase exhibited the highest solubility increase corresponding to 160% up to the solvus at 0.7% 3HBA in SA. The changes in solubility of the CSS phases belonging to the two 3HBA polymorphs were found to diverge with increasing incorporation of SA in the respective crystal lattices. This thermodynamic divergence in combination with the monotropic stability relationship caused the driving force for polymorphic conversion to increase with increasing SA content. This unusual scenario was demonstrated experimentally through the use of solution-mediated phase transformation (SMPT) experiments analyzed in situ by Raman. It was found that the incorporation of 0.5% SA in the crystal lattice of 3HBA form II caused the polymorphic conversion rate to form I to double, in comparison to when 3HBA is chemically pure. The current example thus demonstrates the thermodynamic context for how solid-state miscible impurities can expedite polymorphic conversions. This and other contributions showcase how the rates of crystallization can be enhanced or reduced solely based on formation of CSS with an impurity or additive, without accounting for any surface adsorption effects.

We accelerate a key step in crystal structure prediction (CSP) using machine learning and report its robustness on a wide array of pharmaceutical molecules. The speedup achieved by our scheme allows for a scale-up in both the number of candidate drug molecules studied and the level of theory employed in their treatment, paving the way for tackling more complex crystal energy landscapes.

The substitution of noble metals with cost-effective copper nanoparticles (Cu NPs) in the preparation of metal/semiconductor composite catalysts holds significant environmental and economic implications for the degradation of various organic pollutants. However, the development of highly active and stable Cu NPs catalysts has emerged as a key challenge in the progression of non-noble metal catalysts. In this study, the reducibility of glutathione (GSH) was employed to reduce Cu²⁺ to Cu NPs, resulting in the formation of stable Cu-GSH nanoparticles through S–H bonds. An electrostatic self-assembly strategy was used to load Cu-GSH onto WO₃ nanorods, thereby designing a Cu GSH/WO₃ catalytic material with highly efficient charge transport efficiency. Under visible light irradiation, 3 wt% Cu GSH/WO₃ demonstrated excellent degradation performance for organic pollutants, achieving the degradation of 99.8% of Rh B and 98.6% of TC within 60 minutes. Experimental results from photoelectrochemical (PEC) and electron spin resonance (ESR) analyses indicated that Cu GSH functions as an efficient electron trap, which triggers electron flow driven by the Schottky barrier, capturing the photoexcited electrons from WO₃. This greatly enhances the separation efficiency of WO₃ carriers and extends the lifetime of the carriers. It is hoped that this work will provide a viable approach for the synthesis of new high-efficiency composite photocatalytic materials.

Aluminum hydride (AlH₃) is considered as one of the most promising high-energy hydrogen-storage fuels. Various studies have been conducted to improve its thermostability and compatibility with polar plasticizers. As frequently reported, polyvinylidene difluoride (PVDF) has inherent advantages as a coating agent of AlH₃ to improve its stability and compatibility. However, its optimal content and the interaction mechanisms with AlH₃ are still not clear. In this study, AlH₃ crystals coated with different contents of PVDF have been prepared and their thermochemical properties have been analyzed by using VST and DSC/TG techniques. In addition, the effect of PVDF on decomposition reaction pathways of AlH₃ and AlH₃@Al₂O₃ have been investigated using RMD simulations. It has been found that if the content of PVDF is less than 8%, it may enhance the stability of AlH₃. However, once the content is over 20%, the decomposition of AlH₃ would be promoted. In addition, even if PVDF can inhibit the initial dehydrogenation of AlH₃ during the induction period, once the fast exothermic reactions initiate, the corresponding energy barriers would be lowered with faster H₂ release.

This study probes two solvates of triphenylamine (TPA) bis-urea macrocycle 1 and their activated structures to evaluate their maximum photoinduced radicals (PIRs), the subsequent decay of the radicals, and their regeneration. The hierarchical assembly of TPAs shows promise in stabilizing less substituted derivatives, potentially expanding the utility of TPAs that lack stabilizing para-substituents. Single crystal structure analysis reveals that host 1 adopts a planar conformation with the two ureas pointing in opposite directions when dimethoxyethane (DME) is encapsulated within the channel. Whereas previously, 1 adopted a bowl-shaped conformation with the two ureas pointing in the same direction (syn) with dimethylsulfoxide (DMSO) bound within the channels. Removal of the guests gives identical activated structures. The bulk materials of 1 are characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Finally, the process of radical generation under UV-irradiation, decay, and regeneration of radicals was monitored by electron paramagnetic resonance (EPR) spectroscopy. While macrocycle conformation and extended structure are important, the presence of guests was most significant for PIR percentages.

High-quality transparent cubic lutecia-stabilized zirconia (LSZ) and LSZ:Yb_0.25Tm_0.5Ho_0.03 single crystals were fabricated by the OFZ (optical floating zone) method for the first time. For comparison, YSZ and YSZ:Yb_0.25Tm_0.5Ho_0.03 single crystals were also fabricated. The transmittance of the LSZ single crystal (80.7%) is slightly lower than that of the YSZ single crystal (86.3%) in the visible light region, which is attributed to the LSZ single crystal with a higher density (6.604 g cm⁻³) in comparison with that of the YSZ single crystal (5.973 g cm⁻³). No absorption peaks were observed in the transmission and absorption spectra of LSZ and YSZ within 200–1100 nm, indicating that both crystals are excellent host crystals. The density of LSZ:Yb_0.25Tm_0.5Ho_0.03 single crystals (6.596 g cm⁻³) is also higher than that of YSZ:Yb_0.25Tm_0.5Ho_0.03 single crystals (6.005 g cm⁻³). The absorption spectra of LSZ:Yb_0.25Tm_0.5Ho_0.03 and YSZ:Yb_0.25Tm_0.5Ho_0.03 single crystals exhibited several absorption peaks at 363, 453, 678, and 785 nm and a strong broad absorption band within 850–1000 nm. The upconversion photoluminescence (UCPL) spectrum of the LSZ:Yb_0.25Tm_0.5Ho_0.03 single crystal excited at 980 nm exhibited several emission peaks at 308, 373, 488, 540, 550, 655 and 794 nm; similar emission peaks were observed in the UCPL spectrum of the YSZ:Yb_0.25Tm_0.5Ho_0.03 single crystal. The intensities of the emission peaks of the former are higher than those of the corresponding peaks of the latter, which is due to the former having a higher density and lower phonon energy in comparison with the latter. Power curves indicated that the 308 and 373 nm emissions are 4-photon upconversion processes, the 488 nm emission is a 3-photon process, and the 540 nm and 655 nm emissions are 2-photon processes. These results indicate that under the excitation at 980 nm, the LSZ:Yb_0.25Tm_0.5Ho_0.03 single crystal has high efficiency over the YSZ:Yb_0.25Tm_0.5Ho_0.03 single crystal in ultraviolet and visible light emissions.

Constructing multifunctional films using layered rare earth (RE) hydroxide (LRH) nanosheets as building blocks is a popular topic. The traditional synthesis of LRH films involves four main steps: bulk crystal synthesis, intercalation of long-chain organic anions, exfoliation, and layer-by-layer self-assembly into a film. In this work, the layered gadolinium hydroxide (LGdH) film was directly synthesized via electrodeposition within 10 minutes. The effects of the synthesis conditions, including working voltage, concentration of nitrate solution, and the reaction temperature, on the structural characteristics and morphologies were investigated. In order to improve the photoluminescence performance of LGdH:RE films, the quenching groups in the LGdH structure were removed/replaced via appropriate heat treatment/anion exchange with MoO₄²⁻, based on the thermal behaviour/anion exchange properties of the LGdH, and Gd₂O₃:RE/NaGd(MoO₄)₂:RE films with enhanced photoluminescence and stability were obtained. The electrodeposition combined with heat treatment/anion exchange techniques established in this study led to the rapid synthesis of Gd₂O₃:RE/NaGd(MoO₄)₂:RE films, and could have wide implications for the generation of other types of inorganic functional films.

The degradation of organic dyes under visible light is an effective method to reduce environmental pollution. The key to implementing this method is to develop good photocatalysts. Under hydrothermal conditions, four polyoxometalate-based compounds were prepared, namely, [Co₂(TPTP)₄(H₂O)₄(SiMo₁₂O₄₀)]·4H₂O (1), [Ni₂(TPTP)₄(H₂O)₄(SiMo₁₂O₄₀)]·2.5H₂O (2), {[Cu(H₂TPTP)(TPTP)(H₂O)₃]₂(SiMo₁₂O₄₀)₂}·7.5H₂O (3), and {Cu₂(TPTP)₂(β-Mo₈O₂₆)_1/2}·H₂O (4) (TPTP = 4-[2-(5-pyridyl-4-yl-1,2,4-triazol-1-yl)-methyl]-pyran). Compounds 1 and 2 are isostructural, showing a two dimensional (2D) metal–organic layer. The Keggin anions are discrete between adjacent layers. Compound 3 contains a bi-supporting Keggin anion and a discrete anion. The TPTP ligands in 4 were linked by Cu atoms to form ladder like chains, which are connected by β-Mo₈O₂₆⁴⁻ anions to construct a 2D layer. The compounds can be used as photocatalysts. They have good separation efficiency of photogenerated electron–hole pairs. When compounds 1 and 2 were used as photoelectrocatalysts, they exhibited good photoelectrocatalytic activities. The compounds also exhibit excellent electrochemical performance and can be used as electrochemical sensors for the selective recognition of NO₂⁻ and Cr(VI).

Crystals of trans-3,3′-dimethylazobenzene (DMAB) exhibit crawling motion on solid surface upon simultaneous exposure to ultraviolet (UV) and visible light from opposite directions. In this study, the shape and velocity during the photoinduced crawling motion of DMAB crystals are successfully controlled by irradiation light intensities. A higher intensity of the visible light than the UV light causes the crystals to be spread shape and move slower (∼1 μm min⁻¹). In contrast, a stronger UV light allows them to be droplet-like shape and move faster (∼4 μm min⁻¹). The shape and velocity can be varied by adjusting the light intensities. Shape transformation is effectively applied to cargo capture–carry–release tasks. In particular, spread-shaped crystals capture silica particles over a wide area, whereas droplet-like crystals gather and transport them. This result suggests that a multifunctional soft transporter composed of a single component does not require complex fabrication, thereby contributing to the fields of soft robotics and microfluidics.

Time-resolved studies are crucial for capturing the dynamic evolution of triglyceride structures during crystallization, providing insights into the self-assembly of diverse triglyceride structures across various length scales. While previous research has characterized triglyceride's polymorphisms and long spacings using wide-angle and small-angle X-ray techniques, time-resolved studies on the mesoscale of triglycerides have been limited, particularly in the study of crystalline nanoplatelets (CNPs) and their aggregates. This study pioneers the application of ultra-small-angle X-ray scattering (USAXS) for time-resolved analysis of commercial sources of saturated monoacid triglycerides. The methodology presented here integrates real-time synchrotron X-ray scattering (XRS) with differential scanning calorimetry (DSC), phase contrast microscopy (PCM), and cryo-scanning electron microscopy (Cryo-SEM) to investigate the crystallization behavior of a 30% dilution of palm stearin (PS) in high oleic sunflower oil (HOSO) and a 30% dilution of fully hydrogenated rapeseed oil (FHRO) in HOSO. Covering several orders of magnitude, this comprehensive multiscale approach enhances our kinetic understanding of triglyceride structural transformations. Both systems followed a polymorphic transition from α to β, with a transition from 2L(α) to 2L(β) lamellar stacking configuration. Our results suggest that structural evolutions in non-pure triglyceride systems advance gradually over extended timescales post-crystallization. While lamellae and CNP thicknesses decreased with the polymorphic transition, CNP size and aggregation changed in four distinct phases. We believe that the methodology presented here will greatly improve our understanding of the self-assembly of lipids, getting us closer to bottom-up optimization of triglyceride-based formulations in food.