CrystEngComm最新文献

Understanding the mechanical behaviour of organic molecular crystals is essential for their reliable handling, processing, and performance in solid-state applications. Benzoic acid crystals have been reported to be brittle in previous studies. However, in this work, the benzoic acid crystals grown using slow evaporation and sublimation processes exhibited plastic bending upon the application of force on a wider (001) crystallographic face. Single-crystal X-ray diffraction analysis and pairwise interaction energy calculations revealed the presence of a slip plane along the (001) direction, which was formed mainly due to the herringbone packing arrangement of the benzoic acid molecules and a weak edge-to-edge aromatic interaction. A low-energy (001) slip plane with an interlayer separation of approximately 0.896 Å facilitates the plastic deformation of benzoic acid crystals. Nanoindentation analysis of the (001) face yielded elastic modulus (E) and hardness (H) values of 4.26 ± 0.68 GPa and 128.03 ± 38 MPa, respectively, which fall within the range of values reported for plastic organic crystals.

The technique of Hirshfeld surface analysis has been applied to a selection of crystal structures of metallo-supramolecular grids in order to better define the modes of interaction of the grids with both anionic and neutral species, and to assess the possibilities of using grids as selective receptors. The influence of weak interactions on grid symmetry and hence inequivalence of metal sites within the grids has also been considered as a factor influencing possible electronic uses of grid species.

In this work, we report the synthesis of two new Co(II) metal salts [Co(H₂O)₆](Hpsca)₂·nH₂O (n = 2, 4) incorporating a p-sulfocinnamic acid counter anion (Hpsca⁻). Together with the previously reported iron(II) analogue [Fe(H₂O)₆](Hpsca)₂·2H₂O, these precursors were utilized to synthesize four new coordination complexes [M(bipy)₃](Hpsca)₂·2MeOH (M = Fe (1), Co (2), bipy = 2,2′-bipyridine), [Fe(1-bpp)(Hpsca)(H₂O)(MeOH)]Hpsca·MeOH (3, 1-bpp = 2,6-di(1-pyrazolyl)pyridine) and [Fe(3,2,3-sal₂tet)]Hpsca·H₂O (4), 3,2,3-sal₂tet = 2,2′-((1Z,13Z)-2,6,9,13-tetraazatetradeca-1,13-diene-1,14-diyl) diphenol. Single crystal X-ray diffraction analyses revealed that all complexes consist of discrete mononuclear cationic units, while the Hpsca⁻ anion forms different supramolecular arrangements. ⁵⁷Fe Mössbauer spectroscopy confirms the low-spin state for Fe(II) ions in 1 and Fe(III) ions in 4, in accordance with crystallographic results. This work highlights the versatility of the Hpsca⁻ counteranion to stabilize diverse crystal architectures as well as its ability to couple solid-state reactivity and spin state modulation, thanks to the potential anion-driven light induced spin change based on the solid state [2 + 2] photodimerization of Hpsca⁻.

Single crystals of (L-C₄H₈NO₂S)CuCl₂ (1) and (L-C₄H₇NO₂S)₂ZnCl₂ (2), were obtained using L-thioproline molecules as terminal ligands. The two hybrid metal chlorides exhibit different low-dimensional structures and good second-harmonic generation (SHG) efficiencies of 0.2 and 1.6 times that of KH₂PO₄, respectively. Density functional theory calculations were performed to unravel the origin of the relatively stronger SHG response of compound 2.

Positional isomerism in pyridyl naphthalene diimide formic acid co-crystals controls crystal symmetry, yielding centrosymmetric (I2/a) and polar (Pc) structures from 4- and 2-pyridyl isomers respectively. Both materials function as reversible photochromic switches upon UV irradiation via a proton-coupled electron transfer type mechanism, generating NDI radical anions, as confirmed by UV-vis and ATR-FTIR spectroscopy.

Large-particle ammonium sulfate crystals possess higher commercial value due to their superior physicochemical properties; however, their industrial-scale production remains challenging. Initially, the effects of various operational factors on the crystal size distribution (CSD) of ammonium sulfate in an additive-free system were systematically investigated, and the basic process parameters were determined. Subsequently, two optimized crystallization processes were developed by incorporating composite additives. The results show that the two target systems (constant-rate and deceleration processes) significantly enhance the yield of large crystals, increasing the mass fraction of particles ≥2.0 mm to above 27.00%, compared to less than 5.00% in the conventional process. Crystallinity is also improved from 80.06% in the conventional system to over 87.00%, with a further reduction in crystal aspect ratio. Further crystallization thermodynamics and nucleation kinetics analyses revealed the action mechanism of additives: the additives increase the solid–liquid interfacial energy and widen the metastable zone width (MSZW) of the solution, which inhibits nucleation and promotes crystal growth, thereby providing favorable kinetics for the formation of larger crystals. Moreover, the additives help guide solute deposition in a more ordered manner into the crystal lattice, thus increasing crystallinity. Additionally, the adsorption of additives at active sites on crystal surfaces modifies the relative growth rates of different crystal faces, leading to regulated crystal morphology.

In this study, a series of NiFeCr layered double hydroxide (NiFeCr-LDH) materials with sheet-like morphology and different electronic structure distributions were synthesized via a facile one-step hydrothermal method by adjusting the elemental ratios. As a reliable and stable electrocatalyst, this trimetallic material exhibits prominent advantages in enhancing the kinetics of the oxygen evolution reaction (OER). Under identical catalyst loading, the NiFeCr-3 sample with an Fe : Cr molar ratio of 5 : 3 demonstrated the optimal electrocatalytic performance. This improvement was primarily attributed to the formation of highly active NiOOH species during the catalytic process, while the abundant charge-transfer pathways and variable ionic valence states further contributed to its intrinsic OER activity. In alkaline electrolyte tests, the overpotentials required to achieve current densities of 50 mA cm⁻² and 100 mA cm⁻² were only 287 mV and 331 mV, respectively, with a Tafel slope of 86.5 mV dec⁻¹. Furthermore, the catalyst exhibited excellent long-term stability, maintaining its activity for over 100 hours at a current density of 20 mA cm⁻². Electrochemical measurements and X-ray photoelectron spectroscopy analysis collectively confirmed the synergistic effects among the metal centers in NiFeCr-LDHs. Its catalytic activity was significantly higher than that of NiFe-LDH, indicating the potential of this work for developing high-performance water–alkali electrocatalysts.

This study introduces a dual-heater-coupled laser floating zone (DHC-LFZ) system to overcome the severe thermal stress and cracking that plague the growth of β-Ga₂O₃ single crystals via traditional LFZ methods (T-LFZ). The key innovation lies in the integration of auxiliary resistance heaters into the T-LFZ configuration, which allows for active management of the thermal gradient. A multi-physics finite element model, incorporating coupled phenomena of heat flow, melt convection, interface evolution, radiation, and stress, was established. The results demonstrate that with the introduction of the optimized auxiliary heat source, the DHC-LFZ system effectively stabilizes the melt–crystal interface, achieving reductions of 46% and 50.5% in the axial and radial temperature gradients, respectively. Consequently, the maximum axial and radial thermal stresses are curtailed by 49.4% and 58.9%, providing a significantly improved crystallization environment. Our work clarifies the underlying mechanisms linking thermal field control to crystal quality and offers a viable path toward the low-stress growth of large-sized β-Ga₂O₃ crystals.

Across the CB[8]–imipramine and CB[6]–amitriptyline systems, addition of KI or ZnCl₂ as salt additives can change packing topology, crystal stoichiometry, and channel architecture, while preserving the underlying CB[n]–guest–CB[n] recognition motif. Structural and interaction-energy analyses show that robust local recognition is retained, whereas weaker secondary interactions drive the differences in crystal packing.

Two-dimensional (2D) layered hybrid double metal halide perovskites have recently gained significant attention as lead-free and environmentally benign alternatives to lead halide perovskites. In this study, we report the photophysical properties of a 2D Dion-Jacobson (DJ) type hybrid double perovskite, (C₃H₁₂N₂)₂AgBiBr₈, which exhibits both reversible thermochromism and promising X-ray radiation detection capabilities. This material shows transition from a low-temperature monoclinic P2₁/n phase to a high-temperature monoclinic C2/m phase at 121.83 °C along with a color change from yellow to bright orange. The phase transition is reversible and both single crystals and bulk powder samples of (C₃H₁₂N₂)₂AgBiBr₈ remain stable for more than 30 heating-cooling cycles. Optical property characterization shows that (C₃H₁₂N₂)₂AgBiBr₈ is a semiconductor with an indirect band gap of 2.42 eV. The material demonstrates a semiconductor resistivity of 2.8 × 10¹⁰ Ω cm, lower than those of other reported DJ-type hybrid double perovskites, and also shows response towards soft X-rays (8 keV) with a detector sensitivity of 188.52 μCGy^-1 cm^-2. These properties along with a very high signal-to-noise ratio (SNR) value (111.45) indicate the potential of (C₃H₁₂N₂)₂AgBiBr₈ for direct radiation detection.