Crystal Growth & Design最新文献

Copper iodide-based coordination polymers (CPs) are promising candidates for X-ray scintillation and imaging due to low toxicity, earth abundance, excellent photoluminescence, and strong X-ray absorption stemming from iodine’s high atomic number, but their X-ray scintillation properties remain largely unexplored. In this work, we synthesized three bridging organic ligands by coupling pyridine with 1,2,4-triazole, imidazole, and benzimidazole and obtained three CuI-based CPs. The crystal structure and photo- and X-ray excited luminescence of the three CPs were studied. Among them, CP 3, constructed by {Cu₂I₂} rhombic binuclear units and (pyridin-4-yl)-benzimidazole, exhibited a photoluminescence quantum yield of 72.96%. The decomposition temperature of CP 3 exceeds 240 °C, and its photoluminescence was nearly unchanged after storage in air for 30 days, and then, it was immersed in water for 5 days. CP 3 showed a light yield of 9690 photons MeV^–1 exited by X-ray, which is comparable to the commercial scintillator BGO (10,000 photons MeV^–1). CP 3 was incorporated into a poly(dimethylsiloxane) film, forming a flexible composite film, which showed a spatial resolution up to 11 LP/mm for X-ray imaging, indicating good imaging capability.

As the predominant contributor of Brønsted acid sites, the spatial distribution of framework aluminum in the ZSM-5 zeolite critically governs its catalytic performance in hydrocarbon conversion reactions, such as cracking, isomerization, and aromatization. This study systematically analyzed the effect of aluminum coordination state on the Al pair formation in ZSM-5 synthesis by the QSP method. A comparative analysis was conducted on six aluminum sources in conjunction with the JMAK kinetic model and multiscale characterization. The results show that the coordination state and spatial distribution of aluminum species directly determine the content and distribution of aluminum pairs in the ZSM-5 zeolite. By increasing the alkalinity of the system, the conversion of Al[(OH₂)₆]³⁺ to Al(OH)₄^– was promoted and the content of Al pairs increased from 34 to 74%. It was further found that the aluminum source has a significant effect on the crystallization path by adjusting the nucleation energy barrier (E_n = 32.23–64.31 kJ/mol) and the growth size. This work illustrates the unique advantages of the QSP method in accurately regulating Al pairs and provides theoretical support for the green synthesis of ZSM-5 catalysts.

Compositionally complex oxides have garnered increasing interest for their enhanced phase stability and tunable functional properties, yet their development as bulk single crystal scintillators remains limited. Herein, we report the Czochralski growth and characterization of (Gd_1/4Y_1/4Tb_1/4Lu_1/4)₃Al₅O₁₂:Ce (GYTLAG), a compositionally complex garnet incorporating four dodecahedrally coordinated principal rare earth elements. The garnet phase was confirmed by powder and single crystal X-ray diffraction, and macroscopic defects are described. X-ray absorption near-edge structure measurements confirm the 3+ oxidation state of all rare earths and support their occupation of the same crystallographic site; white line intensity variations correlate with the anticipated segregation behavior. Elemental segregation is quantified by SEM/EDS and ICP-OES, and a linear trend was established between the segregation coefficient and the difference between each rare earth’s ionic radius (r) and the average ionic radius (AIR) of the dodecahedral site. This trend offers a predictive framework for compositional control in future REAG crystals grown by the Czochralski method. Photoluminescence and radioluminescence measurements reveal both Ce³⁺ and Tb³⁺ emission. Scintillation pulses exhibit four-component decay with dominant ∼230 μs and ∼1.2 ms components, and the light yield is estimated to be up to 43,000 ph/MeV under ¹³⁷Cs γ-ray excitation. GYTLAG also demonstrates a strong radioluminescence efficiency and 50% lower afterglow at 20 ms compared to a LuAG:Ce reference, underscoring its promise for scintillator applications.

Bending-to-straightening behavior is vital for both natural processes and advanced materials design. Nonclassical crystallization pathways, particularly amorphous–crystalline transformations, offer opportunities to achieve such dynamic actuation. This study reveals that sugar azides are capable of undergoing spontaneous bending-to-straightening behavior, accompanied by helical deformation, driven by an amorphous–crystalline transformation during anisotropic self-assembly. The process is initiated with bending amorphous nanowires, which evolve into locally crystallized twisted nanoribbons and ultimately straighten into crystalline rectangular hollow tubes through screw dislocation. This transformation is governed by the interplay between the stereostructure of the sugar backbone and the collinear dipole arrangement of the azide group, which together regulates initial helical aggregation and subsequent directional growth. These findings not only clarify the molecular origins of bending-to-straightening crystallization but also provide a strategy for designing responsive materials capable of adapting to unstructured environments.

This study elucidates the spontaneous bending-to-straightening transformation of sugar azide molecules governed by amorphous–crystalline solid transformation. Through the interplay of the sugar stereostructure and azide collinear dipole arrangement, amorphous nanowires evolve into helical nanoribbons and subsequently straighten into hollow crystalline tubes. These insights advance understanding of mechanically responsive crystallization and inform the design of adaptive molecular materials.

While force fields fitted to ab initio data (aiFFs) are generally very successful in crystal structure predictions (CSPs), in some cases spurious polymorphs with low lattice energies may be generated. The presence of such polymorphs makes the experimental crystal rank too poorly in the CSP list. One solution to this problem is to extract nearest-neighbor dimers from a few tens or so of top-ranked polymorphs from the CSP list generated using the initial version of aiFF. The aiFF is then refitted, adding these dimers to the training set, including in this way the relevant dimer-configuration regions explored during CSPs. The refitted aiFF is then used in CSPs. This process is iterative, i.e., extracting dimers, refitting aiFF, and redoing the CSPs is repeated until the error of aiFF with respect to ab initio interaction energies on dimers cut from crystals becomes smaller than a threshold value. Here, we show that this procedure significantly increases the accuracy of refitted aiFF in the regions relevant for CSPs, improving the overall ranking of the polymorph closest to the experimental crystal and actually placing it at rank one. This protocol can be extended to trimers and crystals with flexible monomers.

Transition metal sulfides (TMS) are promising for supercapacitors due to superior theoretical capacity and redox activity compared to metal oxides yet suffer from structural instability and poor conductivity. To overcome these limitations, this study achieved molecular-level homogenization through a glycerol-mediated solvothermal process followed by in situ sulfidation to form a unique fluffy spherical Bi/Co@S heterostructure. This hierarchical design─featuring a porous hollow core and a uniformly sulfurized surface─synergistically improves charge transfer, ion diffusion, and mechanical stability. The resulting Bi/Co@S electrode delivers a high specific capacity of 1514.8 C g^–1 at 1 A g^–1, excellent rate performance (72% capacity retention at 20 A g^–1), and exceptional cycling stability (80.9% capacity retention rate over 10,000 cycles). A hybrid supercapacitor assembled with activated carbon achieves an energy density of 47.67 Wh kg^–1 at 800 W kg^–1, outperforming most previously reported bismuth-based materials. This work offers a novel strategy for designing stable, high-performance TMS electrodes.

Magnetic coupling is one of the most critical factors that reduce the magnetic relaxation of single-molecule magnets (SMMs) and the magnetocaloric effect (MCE) of molecular refrigerants, and studying the magnetic couplings within high nuclearity is a huge challenge. In this work, three novel high-nuclear Co^II₆Ln^III₄ complexes with the molecular formula of [Co₆Ln₄(HL)₄(pdmH)₂(pdm)₈Cl₂]·xCH₃CN·yH₂O (Ln = Gd (1_Gd), x = 3, y = 9; Ln = Dy (2_Dy), x = 0, y = 8; Ln = Er (3_Er), x = 1, y = 6) have been synthesized by employing 2-[[2-(2-hydroxy-ethoxy)-ethylimino]-methyl]-6-methoxyphenol (H₂L) and 2,6-pyridinedimethanol (pdmH₂) to react with Ln(NO₃)₃·6H₂O and CoCl₂·6H₂O in the CH₃CN solution containing triethylamine. Structural analysis revealed that 1_Gd, 2_Dy, and 3_Er are all isostructural, and the cores of the three complexes can be viewed as two Co₃Ln₂O₈ subunits linked by two alkoxido-type O atoms from two pdm^2– ligands. In each subunit, three Co^II atoms, two Ln atoms, and eight O atoms form three defective cubanes. Magnetic studies indicate that only 1_Gd and 2_Dy show slow magnetic relaxation behavior under a zero dc field. However, complex 3_Er cannot exhibit any out-of-phase (χ″) ac susceptibility signals. The discrepancies of the temperature-dependent χ″ signals of 1_Gd, 2_Dy, and 3_Er revealed that their slow magnetic relaxation behavior would decrease from oblate Dy^III to prolate Er^III. Additionally, 1_Gd exhibits the MCE with a magnetic entropy change −ΔS_m of 26.68 J kg^–1 K^–1 at ΔH = 7 T and T = 3.0 K, to our knowledge, which is high among the reported polynuclear complexes. The direct current (dc) data of the three complexes have been simultaneously fitted well by POLY_ANISO calculations. Moreover, the anisotropies of Co3 and Dy2, larger than Co2 and Dy1 from the ab initio calculations, are almost consistent with the results from the Hirshfeld surface analysis.

Glioblastoma is a highly aggressive brain tumor with a poor prognosis and limited treatment options. Resveratrol (RES) and temozolomide (TMZ) both showed significant antitumor activity in GBM therapy. However, they are limited by poor solubility and stability, respectively. This study reports the first successful development of a resveratrol–temozolomide (RES–TMZ) cocrystal. The cocrystal significantly improved the solubility of RES and stability of TMZ, while it exhibited enhanced oral bioavailability in rats. In vitro cytotoxicity assays revealed that the RES–TMZ cocrystal showed superior inhibitory effects on U87 glioma cell proliferation and induced a higher apoptosis rate compared to that of monotherapy or physical mixtures. Mechanistic studies further demonstrated that the cocrystal exerts its effects through the mitochondrial-dependent apoptotic pathway, characterized by the upregulation of the proapoptotic protein Bax, downregulation of the antiapoptotic protein Bcl-2, activation of the caspase-3 pathway, and collapse of mitochondrial membrane potential coupled with a burst of intracellular reactive oxygen species. This work establishes pharmaceutical cocrystallization as a viable strategy to develop improved combination therapies for glioblastoma by overcoming drug limitations while potentiating therapeutic effects.

This study investigates the supramolecular properties of fluorinated compounds by analyzing fluorine–oxygen (F···O) intermolecular interactions, which play a subtle but important role in molecular packing. Combining data from crystal structures with high-level quantum-mechanical calculations and QTAIM topological analysis, the geometric and energetic characteristics of F···O interactions were examined. Over 52,000 interactions were identified using a 3.5 Å cutoff, ranking them as the third most common fluorine-based interactions in crystal structures after C–H···F and F···F interactions. The influence of the surrounding chemical environment, as well as the nature of substituents on the interacting atoms, was assessed. Quantum mechanical analyses, including high-level CCSD(T)/CBS calculations, show that these interactions are weak (−0.77 to −2.55 kcal/mol) but stronger than F···F and C–H···F interactions and comparable to C–H···O interactions, with more geometric flexibility. The observed geometry is influenced by crystal packing, cooperativity, and the presence of multiple simultaneous interactions. Energy minima typically occur between 2.9 and 3.5 Å, often with antiparallel orientations. Together, the statistical and computational results establish F···O interactions as meaningful contributors to supramolecular organization and provide a framework for their inclusion in crystal engineering and computational modeling.

Stimuli-actuated dynamic bond switching enables the modulation of chemical and physical properties in a precise and coherent way, rendering molecular materials broad applications in molecule-based motors, sensors, and energy storage devices. To date, the majority of dynamic bond switching occurs between neutral ligands and cationic metal ions. Herein, we report a new dynamic crystal Cd^II(L)₂(NO₃) (1; L = 4-morpholineethanamine) that features the reversible bond switching between the anionic nitrate ion and the cationic cadmium ion. Single-crystal X-ray diffraction analysis indicated that one of the Cd–O1(nitrate) bonds experienced unprecedented elongation from 2.489 (3) Å at 300 K to 2.739 (2) Å, while the rest of the Cd–O2(nitrate) bond showed insignificant variation from 2.467 (3) Å at 300 K to 2.325 (2) Å at 120 K. The anomalous bond length variations lead to the transformation from symmetric one in high-temperature phase (300 K) to asymmetric coordination mode in low-temperature phase (120 K). Such unusual dynamic bond variations also caused continuous structural phase transitions from phase I (above 235 K) to phase II (from 235 to 145 K), and then phase III (below 145 K), wherein the transition from phase I to phase II is of the first order. Compound 1 also exhibited the anisotropic negative thermal expansion (NTE) effect in phase II, which is managed by the deformation of Cd-centered polyhedron and rearrangement of intermolecular interactions. This work demonstrates that utilizing flexible nitrate units is a feasible approach in designing novel dynamic crystalline compounds with switchable structures and functions.