CrystEngComm最新文献

Two new nitrogen-rich energetic salts based on 5,5′-dinitramino-3,3′-methylene-1H-1,2,4-bistriazolate (DNAMT), namely, (DAG)₂(DNAMT)·4H₂O (1) and (NH₃OH)(DNAMT) (2), were designed and synthesized, and they were characterized by IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The thermal stability of the two salts were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The decomposition temperatures of 1 and 2 were determined to be 221.2 °C and 214 °C, respectively. The apparent activation energies (E_a) of the thermal decomposition processes of 1 and 2 were 189.2 and 218.9 kJ mol⁻¹, respectively. Compound 1 had appropriate impact sensitivity (11.5 J) and was friction-insensitive (>360 N). In contrast, compound 2 was an impact- and friction-sensitive explosive (IS: 3 J; FS: 56 N). The detonation properties of compounds 1 and 2 were calculated using EXPLO 5 (V6.04) based on their experimental densities and calculated heats of formation. The detonation properties of 1 (D: 7943 m s⁻¹ and P: 21.20 GPa) and 2 (D: 8339 m s⁻¹ and P: 26.75 GPa) dramatically exceeded those of TNT but were lower than those of RDX. Meanwhile, compounds 1 and 2 possessed higher nitrogen contents (53.83% and 50.82%, respectively). Both compounds displayed good thermal stability, high energetic properties and low sensitivities as high nitrogen content energetic materials.

Monodisperse particles of zinc gallium oxide have been synthesized via coprecipitation under hydrothermal conditions in the presence of trisodium citrate, which acts as a ligand for the reactant metal ions to establish controlled homogeneous nucleation at an elevated temperature. This procedure enables the particle size to be tuned up to about 200 nm by changing the citrate concentration. Also, the spinel crystal structure can be maintained when the compositional ratio of Ga to Zn in the particle, f_Ga/Zn, varies, at least in the range of f_Ga/Zn = 1.3–2.7, depending on the citrate concentration and/or Ga³⁺/Zn²⁺ ratio in the reacting solution. The absorption edge of the diffuse reflectance spectra suggests that the present particles possess a band gap of 4.7–4.9 eV, which is almost independent of the synthesis conditions.

This study explores diffusion-assisted synthesis in rigid gel matrices, utilizing reaction–diffusion processes to fabricate crystalline materials with controlled size and morphology. The presented techniques focus on synthesizing various classes of materials, such as inorganic precipitates, metal–organic frameworks, and gold nanoparticles, using gel column and flow-through gel reactors, as well as reactive wet stamping. In these setups, the reagents are initially spatially separated, and one of the reagents diffuses into gels containing the other reagent, producing crystals with sizes that increase linearly from the gel interface. The gel matrix prevents sedimentation and aggregation, allowing the undisturbed growth of larger crystals. Additionally, the experimental setup provides a spatiotemporal control over the mass flux of the reagents, thus controlling the rates of nucleation and crystal growth. Theoretical models can explain the linear dependence of the crystal size and attribute larger crystal sizes to regions of lower supersaturation, which favor growth over nucleation. We also discuss advanced methods, including orthogonal diffusion and electric field-assisted synthesis, that can enhance spatial control and crystal morphology. Compared to traditional bulk wet synthesis, diffusion-assisted methods offer exceptional control over crystal size, shape, and dispersity. Prospects include scaling up macroscopic crystal synthesis, refining reactor designs for 2D and 3D configurations, and exploring applications in catalysis, biomedicine, and environmental remediation.

Cultural heritage refers to intangible traditions and tangible artifacts. The latter have been at the epicenter of several scientific disciplines, mainly in the framework of preservation. An important and integral part of the preservation of cultural heritage objects (large or small) is the application of chemical consolidants. These are chemical compounds (inorganic, organic, or hybrid) that are used to stabilize and strengthen deteriorating artifacts, structures, or artworks. Important attributes of a consolidant for managing stone deterioration include high penetration depth, chemical compatibility with the stone, and the ability to improve mechanical properties, while minimizing the risk of accelerated degradation or aesthetic changes. This Highlight attempts to correlate the action of consolidants with the stone through the tools of crystal engineering. It presents selected information on inorganic, organic, and multifunctional consolidants, and focuses on the possible mechanisms of the consolidating action through the “eyes” of the chemist/crystal engineer.

Antimonene, as an emerging 2D pnictogen-based material, has attracted significant attention due to its theoretically predicted outstanding electronic performance. However, its synthesis remains challenging due to strong interlayer van der Waals interactions, regardless of whether top-down or bottom-up approaches are employed. Conventional liquid-phase synthesis can produce high-quality antimonene nanosheets, but it typically requires toxic thiols or residual-prone alkyl phosphonic acids as templating agents, which inevitably introduce environmental concerns and complex purification requirements. Here, we successfully synthesized antimonene nanosheets using oleylamine as a substitute for thiols and alkyl phosphonic acids, achieving a simplified and environmentally friendly preparation process. The as-prepared antimonene nanosheets exhibit a distinct photoresponse. Our study reveals that this phenomenon originates from surface adsorbates, which undergo reversible photo-induced adsorption and desorption under irradiation. This process effectively modulates the charge carrier concentration, ultimately leading to the observed broadband photoresponse.

Solid-state photochromism is often suppressed in organic crystals by packing constraints. Herein, we report the coordination-driven activation of pronounced photochromism in a series of zinc(II) complexes with N-substituted 4-amino-1,2,4-triazole ligands. X-ray crystallography shows that coordination to Zn(II) disrupts the ligands' inherent intermolecular hydrogen bonds, locking them into a conformation favorable for excited-state intramolecular proton transfer (ESIPT). Diffuse reflectance spectroscopy confirmed UV-induced photochromism in four of the five synthesized complexes. A quantitative energy analysis of intermolecular interactions, combining Hirshfeld surface analysis and QTAIM, identified π–π stacking as the key modulator: the only non-photochromic complex in the series served as a key example, exhibiting the strongest stacking interactions. We conclude that metal coordination provides the structural prerequisite for ESIPT, while the specific supramolecular packing, particularly the strength of π–π stacking, ultimately gates the photochromic response. This work illustrates the potential of metal coordination as a tool for engineering photochromic behavior in crystalline materials.

WO₃ nanoparticles were synthesized on a gram scale within 120 seconds via a dynamic magnetic field transportation (DMFT) technique. The size control of WO₃ nanoparticles was achieved by adjusting the furnace pressure. The final WO₃ nanoparticles exhibited a relatively uniform size distribution (d = 62.1 ± 18.8 nm), suggesting the variance was very small. The WO₃ nanoparticles also possessed the property of absorbing ultraviolet light ranging from 200 nm to 400 nm. The as-synthesized uniform WO₃ nanoparticles hold broad application prospects towards various fields such as ultraviolet shielding and as a nanoscale tungsten carbide (WC) precursor.

In the field of hydrogen energy development and exploration, the development of energy-saving, environmentally friendly, highly efficient and practical hydrogen production catalysts is of utmost importance for the development of energy fields. In this work, a sea urchin-like nanocluster electrocatalyst (La-Ni₃S₂@FeOOH) was successfully synthesized on a nickel foam substrate. The prepared catalyst exhibits good electrochemical performance in a simulated seawater electrolyte. It has relatively low overpotentials of 249 mV and 367 mV at current densities of 10 mA cm⁻² and 50 mA cm⁻², respectively. Additionally, the Tafel slope is 39.13 mV dec⁻¹ at 10 mA cm⁻²; it has a large electrochemically active surface area and a small electrochemical impedance, and remains stable during a long-term stability test for 100 hours. The excellent performance of the catalyst is likely due to the incorporation of rare earth element La, which promotes the occurrence of redox reactions and thus optimizes the electronic structure of materials. Moreover, the unique surface morphology not only provides a large number of active sites, but also effectively promotes the infiltration of the electrolyte on the surface of the catalyst and the desorption of bubbles. This method provides a new idea for the development of economical and environmentally friendly electrocatalysts for the oxygen evolution reaction.

Brownmillerite-type Ca₂Fe₂O₅ is a mixed ionic and electronic conductor with applications as an electrode material for solid oxide fuel cells and solid oxide electrolyser cells. Long-range oxide ion migration in Ca₂Fe₂O₅ has been computationally predicted to be predominantly two-dimensional, restricted to the (ac) crystallographic plane. We have used the floating zone method to grow large high-quality single crystals of Ca₂Fe₂O₅ and determine its conductivity on two differently oriented single crystal samples in order to directly probe the anisotropy of transport properties. Impedance spectroscopy measurements have shown the conductivity in the (ac)-plane to be up to one and a half order of magnitude higher than that parallel to the crystallographic b-axis. This degree of anisotropy of the conductivity is higher than that observed experimentally in most other oxide ion or mixed conductors belonging to the apatite and melilite structural family, highlighting the suitability of brownmillerite-type materials for applications in devices requiring components in oriented crystal or thin-film forms.

To enhance the 3.9 μm emission of Ho:⁵I₅ → ⁵I₆ transition, this work proposes for the first time the use of Ni²⁺ as a sensitizer. Ni²⁺, Ho³⁺, and Ni²⁺/Ho³⁺ co-doped PbF₂ single crystals were grown by the Bridgman method for verification. Spectroscopic characterization confirmed the effective enhancement of Ho³⁺ emission at 3.9 μm by Ni²⁺, with the emission cross-section increasing from 0.3 × 10⁻²⁰ cm² to 0.51 × 10⁻²⁰ cm². Fluorescence lifetime measurements of the lower ⁵I₆ level revealed a Ho³⁺:⁵I₆ → Ni²⁺:³T_2g(F) energy transfer efficiency of up to 79.7%, significantly surpassing previous Nd³⁺/Ho³⁺ co-doped systems. Furthermore, simulation experiments for a 3.9 μm laser based on the Ni²⁺/Ho³⁺ co-doped PbF₂ crystal were conducted. The simulations further demonstrated the sensitization effect of Ni²⁺ on Ho³⁺ 3.9 μm emission, predicting a theoretical output energy value of 2.88 mJ under a 500 mJ pump input. Therefore, the Ni²⁺/Ho³⁺:PbF₂ single crystal is demonstrated to be a promising gain medium for 3.9 μm solid-state lasers.