Abstract Advancement in multifunctional molecule-based material represents a significant branch in material chemistry. Specifically, the integration of distinct key physical properties into a single molecular system may yield interplay among them, providing functionalities beyond mere superposition. However, major challenges include preserving magnetic performance during assembly and incorporating multiple functionalities synergistically. Herein, we report the engineered assembly of Dy3+-based pseudo pentagonal bipyramidal single-molecule magnets cations with anionic bismuth halides, forming ion-pair hybrids, [Dy(Cy3PO)2(H2O)5][Bi2Br9]·2Cy3PO·2CH3CN (1) and [Dy(Cy3PO)2(H2O)5][Bi2Br9]·2Cy3PO·H2O·CH3CH2OH (2) (Cy3PO = tricyclohexylphosphine oxide). Both compounds exhibit slow magnetic relaxation with high effective barriers of 530 and 563 K, as well as magnetic hysteresis up to 15 K. Additionally, their noncentrosymmetric space groups (Pna21 for 1, P21 for 2) enable second harmonic generation. These two distinct properties are achieved not merely through the superposition of individual components but via an engineered, structure-preserving assembly. This work demonstrates an effective strategy for designing multifunctional molecular nanomagnets with predictable and enhanced performance.
Abstract High-pressure and high-temperature (HPHT) heteroepitaxy enables diamond growth with dislocation densities approaching those of homoepitaxial crystals, yet the role of the amorphous carbon interlayer at the heterointerface remains poorly understood. Here, we investigate the nucleation and growth behavior of diamond on amorphous glassy carbon under HPHT conditions. Diamond nucleation on amorphous glassy carbon is achieved at 5.5 GPa by tuning nucleation temperature and duration, followed by single-crystal growth on the amorphous substrate. The resulting heteroepitaxial diamonds exhibit RC full widths at half maximum of 0.0037°−0.0142°, corresponding to dislocation densities as low as 105−106 cm−2, comparable to conventional HPHT single crystals. Finite element simulations reveal that the confined growth structure reduces carbon concentration during the initial growth stage, suppressing random multi-site nucleation and polycrystalline competition, thereby enabling continuous growth from limited nucleation sites. In addition, stable growth on large-diameter glassy carbon seeds requires increased pit depth to provide sufficient relaxation time. These results clarify the role of amorphous carbon in HPHT heteroepitaxy and provide a feasible route for expanding seed selection in diamond growth.
Abstract Hydrate formation on ice is an interfacial crystallization process governed by thermodynamic driving force and the evolving state of the ice surface and hydrate shell. Here, in situ micro-X-ray computed tomography was used to visualize xenon hydrate formation on single ice particles after ethanol-vapor exposure from −50 to −5 °C under different operational ethanol addition levels. These levels were defined by injection duration and do not represent measured interfacial ethanol doses. Without ethanol, hydrate formation proceeded slowly through surface-layer growth; at −50 °C, only a very thin local hydrate layer was observed after 77.8 h. Under high operational ethanol addition at −10 °C, the ice surface evolved before xenon charging, followed by loose flocculent hydrate formation, shell growth around a shrinking ice core, and late-stage hydrate dissociation. At −20 °C, increasing operational ethanol addition was associated with an ordered progression toward greater shell roughness and spatial heterogeneity. At −50 °C, a clear shell was visible by 620 min after xenon charging without XCT-resolved pre-charging surface deformation. Thus, the XCT observations establish distinct, condition-dependent pathways of hydrate-shell development and persistence following ethanol-vapor conditioning, while their molecular origins require further compositional and spectroscopic verification.
Abstract Polyhedral connectivity offers a crystal-chemical route for understanding anisotropic properties in low-symmetry solids. Here, layered monoclinic GeS2 is investigated as a mixed-connectivity tetrahedral system composed of corner-sharing Ge−S−Ge bridges and edge-sharing Ge2S2 units. Polarization-resolved Raman spectroscopy combined with phonon calculations reveals strongly mode-dependent vibrational polarizability within the interconnected GeS4 framework. First-principles calculations show S-p-dominated valence states, Ge−S-hybridized conduction states, and an energy-dependent interchange of the preferred in-plane absorption direction. Polarization-resolved absorption measurements confirm this behavior through a sign change in the normalized linear-dichroism contrast between 266 and 336 nm. ADRDM further verifies spatially coherent dielectric anisotropy, while a GeS2 device converts the 266 nm optical anisotropy into a reproducible polarization-dependent photocurrent with a ratio of approximately 1.92. These results establish mixed GeS4 connectivity as a crystal-chemical framework linking lattice dynamics, electronic structure, and wavelength-dependent linear dichroism.
Abstract Discovering sulfate optical crystals with enhanced birefringence and a broad transparency window is of great interest but remains challenging. Herein, two new rare-earth sulfate crystals NaNH4Y2(SO4)4 and NaKY2(SO4)4 were designed and successfully synthesized by introduction of rare-earth Y3+ ions into alkali metal sulfates. Transparent millimeter-sized single crystals were grown by a facile hydrothermal method, with NaNH4Y2(SO4)4 reaching dimensions up to 4 × 4 × 2 mm3. Both compounds are isostructural and built from identical structural units, namely [YO8] dodecahedra and [SO4] tetrahedra. They exhibit enhanced birefringence (0.040−0.044 at 550 nm) and a broad optical transmittance range with absorption cut-off edges below 200 nm. This work provides a valuable pathway for developing sulfate optical crystals that combine broad optical transparency with enhanced birefringence.
Abstract Rucaparib (RUCA) is an orally administered PARP inhibitor with an important clinical value in cancer therapy, but its poor aqueous solubility remains a major challenge for improving its dissolution behavior and pharmaceutical performance. In this study, drug−drug salt formation was adopted to improve the physicochemical properties of RUCA by selecting three nonsteroidal anti-inflammatory drugs, namely, flurbiprofen (FLU), ibuprofen (IBU), and naproxen (NAP), as salt-forming components. Three salts (RUCA-FLU, RUCA-IBU, and RUCA-NAP) were successfully obtained, and their structures and solid-state properties were systematically characterized by X-ray diffraction analysis, thermal analysis, FT-IR, 1H NMR, Hirshfeld surface analysis, independent gradient model based on Hirshfeld partition (IGMH) analysis, molecular electrostatic potential, and HOMO−LUMO. Structural results confirmed that three salts were formed through acid−base proton transfer with lattice stabilization arising from multiple N−H···O hydrogen-bonding interactions. Among them, RUCA-NAP showed the best overall performance, exhibiting a RUCA solubility 2.78-fold that of free RUCA and a cumulative dissolution percentage 1.66-fold that of free RUCA in water. All salts exhibited acceptable solid-state stability during the 8 week long-term stability study. In vitro antitumor assays against J82 bladder cancer cells showed that RUCA-FLU and RUCA-NAP displayed 3.38-fold and 1.95-fold stronger cytotoxicity than that of RUCA, respectively. Overall, this work demonstrates that drug−drug salt formation is a robust approach for modulating the solid-state properties, dissolution behavior, and biological performance of RUCA.
Abstract We report the synthesis, crystal structures, and magnetic properties of three tetranuclear [M2Dy2] complexes, [Dy2Ni2(Hhmb)2(hmb)2(NO3)2(IMA)2] (1), [Dy2Cu2(Hhmb)2(hmb)2(NO3)2(IMA)2]·Acetone (2), and [Dy2Cu2(Hhmb)2(hmb)2(H2O)4(IMA)2](CF3SO3)2·4THF·2Acetone (3) (H2hmb = 2-hydroxy-3-methoxyphenyl)methylene(benzonicotino)hydrazine; HIMA = Imidazole-1-ylacetic acid). These complexes feature a rare stair-like topology enforced by a rigid dual-protonation ligand framework. This step-like arrangement maintains a central {Dy2} core while positioning the 3d metal ions at relatively large distances, providing a platform to probe the influence of remote paramagnetic centers on relaxation dynamics. Magnetic measurements reveal field-induced slow relaxation of the magnetization for complexes 1 and 2, with markedly slower relaxation in the Ni2+ analogues compared to the isomorphous Cu2+ derivative, highlighting a detrimental effect of the paramagnetic Cu2+ centers despite their remote position. Ab initio calculations reveal that while 1 and 2 share nearly identical single-ion anisotropy profiles, the remote Cu2+ centers introduce weak dipolar fields that might accelerate the quantum tunneling. For complex 3, the introduction of coordinated water molecules directly alters the coordination sphere, weakening the local axial crystal field and further exacerbating these disruptive effects. This work underscores the need to jointly consider single-ion axiality and long-range dipolar coupling when designing heterometallic single-molecule magnets.
Abstract Photoelectrochemical (PEC) water splitting is a promising technology for producing clean hydrogen, but the slow rate of the oxygen evolution reaction (OER) severely limits its overall efficiency. WO3 is a competitive n-type semiconductor for OER photoanodes owing to its low cost, good electron mobility, and suitable band structure. In this study, we successfully fabricated WO3 photoanodes with preferred (002) crystal orientation via a simple sol−gel concentration strategy, without introducing any dopants or crystal-directing agents. The influence of calcination temperature and film thickness on PEC performance was systematically explored, and 500 °C was verified as the optimal calcination temperature for a well-crystallized structure and fast charge transfer. Under AM 1.5G simulated solar light and an applied potential of 1.57 V vs. RHE, the single-layer WO3(002) photoanode achieves a photocurrent density of 0.40 mA cm−2. Further thickness regulation via multi-layer spin-coating greatly improves light absorption and charge separation, and the optimized sample delivers a high photocurrent density of 2.11 mA cm−2. Characterizations confirm that the concentrated precursor effectively induces selective growth of active (002) facets. This work proposes a low-cost, scalable approach to tailoring WO3 crystal facets, providing valuable guidance for designing high-performance photoanodes for efficient PEC water splitting.
Abstract Based on the significant difference in interfacial creeping behavior between ammonium chloride (NH4Cl) and hexamethylenetetramine (C6H12N4, HMTA), this work proposes a spatial gradient-based pre-enrichment strategy for multicomponent mixtures. Unlike conventional sequential fractional crystallization, which relies on precise temporal control of process conditions to induce successive precipitation of different solutes, our approach enables preferential accumulation of distinct components in different regions of a substrate during a single evaporation step, thereby generating a compositional gradient. Using the NH4Cl−C6H12N4 binary system derived from glycine production mother liquor as a model, experiments demonstrate that crystal creeping produces concentric ring patterns with clear spatial differentiation: the inner region is enriched in NH4Cl, while the outer creeping zone is relatively enriched in C6H12N4. A single creeping cycle achieves only pre-enrichment rather than complete separation; however, repeated cycles progressively improve purity, raising the NH4Cl content from 80.11% to 92.87%. This gradient-partitioning approach is mild in conditions and simple to operate, offering a preliminary enrichment strategy for multicomponent mixed salt systems.
Abstract Self-assembly of discrete helical structures using artificial molecules has long attracted considerable attention in supramolecular chemistry. Nevertheless, the studies of anion-templated subcomponent self-assembly for constructing supramolecular helical architectures in a one-pot fashion are scarcely reported. In this study, a novel and discrete A2L3-type (A = anion, L = ligand) triplet-stranded helicate, 1, was efficiently fabricated by anion-templated subcomponent self-assembly (ATSSA) from a PO43−anion, monotopic aniline L0 with a bisurea moiety, and terephthalaldehyde in a one-pot fashion. Additionally, the triple helicate 1 was also able to be constructed by anion coordination-driven assembly (ACDA) from PO43− with Schiff-base ligand L1 formed by imine condensation. The self-assembly of triplet-stranded helicate 1 was elucidated by single-crystal X-ray diffraction (SCXRD) analysis, and experimental spectroscopic data including 1H NMR and high-resolution ESI-MS confirmed the supramolecular helical configuration. Interestingly, upon introducing 4-tert-butyl-2,6-diformylphenol into the initial subcomponent self-assembly system of helix 1, the other fluorescent A2L3-type triplet-stranded helicate, 2, was also capable of being generated in situ through replacing terephthalaldehyde. Furthermore, the discrete helix 2 exhibited reversible disassembly and reassembly behaviors triggered by external acid-base stimuli. This work is expected to offer new insights and rational design strategies for fabricating anion-directed supramolecular helical architectures and may also lay a promising foundation for the construction of supramolecular smart materials.
Abstract Energetic compounds typically exhibit a certain degree of acidity; however, excessive acidity can cause corrosion of the charging casing, thereby limiting their application. To investigate the potential of self-assembly technology in modulating the acidity of explosives, this study prepared two self-assembled energetic materials, namely TNP-ATRZ and TNP-TTDO, using the typical acidic explosive TNP as a ligand. Through pH measurements, it was revealed that the acidities of TNP-ATRZ and TNP-TTDO decreased by 41.2% and 73.6%, respectively, compared with that of TNP. Further analysis of intermolecular interactions using Hirshfeld surface analysis and noncovalent interaction calculations indicated that hydrogen bonding not only serves as the primary driving force for the formation of the self-assembled energetic materials but also plays a key role in reducing explosive acidity. Additionally, differential scanning calorimetry (DSC) tests revealed that the decomposition temperatures of TNP-ATRZ and TNP-TTDO are 265.1 and 254.4 °C, respectively, both exceeding 250 °C, which indicates good thermal stability. Detonation performance calculations and sensitivity tests revealed that both materials achieve detonation performance and sensitivity superior or comparable to those of the raw materials. Therefore, self-assembly technology not only regulates the overall performance of energetic materials but also synergistically addresses the issue of explosive acidity, thereby advancing the application of strongly acidic energetic compounds.
Abstract Antimony (Sb) thin films are increasingly crucial in semiconductor technology due to their unique electronic and optical characteristics. Pulsed laser deposition (PLD) enhances their production by improving control over film microstructure and addressing uniformity challenges. The mechanical properties of Sb films, especially their behavior under mechanical stress and the associated twinning phenomena, are not well understood. This study employs nanoindentation and electron microscopy to investigate the mechanical properties and twinning behavior of Sb films deposited by PLD. Utilizing SEM and TEM, we analyze the structural changes these films undergo under stress, with a particular focus on deformation twinning, which critically affects their strength. Our findings confirm that deformation twinning, in particular, rhombohedral twinning plays a key role in determining the mechanical properties of Sb thin films. Nanoindentation reveals an activation volume of (2.75–3.85)b3 and a strain rate sensitivity of about 0.05 for Sb films. This research not only fills the existing knowledge gap about the mechanical behaviors of Sb thin films but also highlights the potential of PLD in producing high-quality films for high-performance applications, such as phase change materials, highlighting the transformative potential of PLD in tailoring the mechanical properties of thin films, crucial for next-generation electronic and optical devices.
Abstract Single crystals of lanthanide orthoborates containing Nd, Sm, Eu, Gd, and Tb, which crystallize in the vaterite structure, were synthesized via a subcritical hydrothermal method. NdBO3 has not previously been reported in the vaterite structure, and other compositions have only been reported as polycrystalline powders. These single-crystal structures are the first example of orthoborates crystallizing in the vaterite structure and can help in a more extensive characterization of these phases. The single-crystal structure data provide evidence for lanthanide orthoborates containing Nd, Sm, Eu, Gd, and Tb crystallizing in a disordered hexagonal vaterite polymorph. These data can help resolve existing ambiguities in the structural description of vaterite-type rare-earth orthoborates and offer a future structural framework for understanding their optical and magnetic behavior.
Abstract Understanding the microscopic nucleation and growth mechanisms of gas hydrate under confinement is crucial to develop the rapid hydrate nucleation technology for energy utilization and carbon sequestration. In this work, large-scale molecular dynamics simulations are used to explore the effects of confined dimensions, ratios of water to gas, and interfacial hydroxyl contents on methane hydrate nucleation and growth under confinements. Our simulation results demonstrate that hydrate nucleation and growth are strongly associated with the confined dimensions and interfacial interactions. Strong hydrate nucleation and growth occur more readily at low confined dimensions of 57.12 and 59.12 Å, yet weak hydrate growth behavior prefers a high confined dimension of 61.12 Å. Furthermore, at the ratio of water to gas of 3.75, methane hydrates exhibit the most rapid growth among the systems with various ratios of water to gas ranging from 1.75 to 9.75, resulting from sufficient guest molecules and efficient mass transfer. Interestingly, hydrogen-bond hydrate seed structures and hydroxyl groups on graphene oxide can induce water molecules to preferentially arrange at hydrate-solution and solution–substrate interfaces through interfacial interactions, leading to lateral hydrate growth toward the solution phase and longitudinal hydrate growth toward the solid substrate interface. This study not only reveals the microscopic manners of hydrate phase transitions under artificial or natural constrained environments, but also elucidates the regulation mechanism of interfacial interactions on hydrate growth pathways under complex confinements.
Abstract The regulation of polymorphic behavior by substituents involves a complex interplay of steric and electronic effects that are difficult to decouple. Herein, using −Cl and −CH3 substituents of comparable van der Waals volumes yet opposite electronic characters, we investigated the polymorphic behavior of three salicylideneaniline derivatives. All three compounds form a rare pair of isostructural polymorph families: a yellow, twisted herringbone form and an orange, planar lamellar form, providing an ideal platform for examining charge effects under a constant spatial framework. Within this template, although dispersion is the largest energy contributor in all polymorphs, the dominant factor determining the relative stability difference between the two forms undergoes a fundamental switch: in the chlorine-containing systems, the electrostatic term difference dictates the stability ordering, whereas in the methyl-substituted system, the electrostatic terms are nearly equal and the net dispersive advantage becomes decisive. Solid-state phase-transition temperatures, interfacial crystallization rates, and solid-state fluorescence properties further demonstrate that charge effects extend from static thermodynamics to dynamic kinetics and photophysics. We thus establish, for the chloro- and methyl-substituted salicylideneaniline systems studied here, a “spatial template defines the scaffold, charge effect imparts the details” model, offering an independent electronic dimension for rational polymorph design beyond conventional steric optimization.
Abstract Controlling supramolecular architecture through systematic variation of host–guest stoichiometry remains a fundamental challenge in materials design. Here, we demonstrate that flexible dicationic linkers enable unprecedented structural control in multicomponent calixarene assemblies. Two dicationic salts, bis(phenoxymethyl)benzene-dipyridinium and bis(methylene)benzene-dipyridinium halides, readily assemble into five distinct self-assembled architectures with p-sulfonatocalix[4]arene (SC4) and gadolinium(III) ions, modulated by varying molar ratios of a monophosphonium cation. Remarkably, the conformational flexibility of the longer dication drives dramatic transitions in packing motifs─progressing from a conventional bilayer (11.2 Å) to a molecular capsule (16 Å), and ultimately to a grid-like metal–organic framework assembly (18 × 6 Å pores) with 58.5° inclined molecular dimers. In contrast, the shorter, more rigid dication exclusively forms bilayer structures with well-defined water tunnels in the extended assembly (14 × 9 Å channels). Most notably, we report the first example of dual guest inclusion within a single calixarene cavity, where both a phosphonium phenyl ring and a pyridinium terminus simultaneously occupy the same SC4 host.
Abstract Fire and explosion accidents caused by thermal runaway of lithium-ion batteries (LIBs) have seriously hindered the development of their high-energy-density applications. Herein, we designed and synthesized a novel ZIF-67@COF hybrid material and incorporated it into an epoxy resin (EP) matrix to prepare a composite coating for passive thermal protection of LIBs. By in situ growth of a covalent organic framework (COF) on the surface of aminated ZIF-67 via a solvothermal method, a ZIF-67@COF flame retardant with a heterogeneous interface was successfully constructed. With the addition of 5 wt % ZIF-67@COF, the peak heat release rate (PHRR) and total smoke production (TSP) of the EP composite were significantly reduced by 38.5% and 19.4%, respectively, compared with neat EP, demonstrating an excellent synergistic flame-retardant effect of condensed-phase char formation and gas-phase radical scavenging. When the optimized ZIF-67@COF coating was applied onto the surface of commercial 103450 batteries, thermal runaway tests showed that a 100 μm-thick coating delayed the thermal runaway onset temperature from 200.1 to 240.2 °C, extended the voltage drop onset time from 929 to 1014 s, greatly suppressed flame intensity, and effectively blocked propagation of chain thermal runaway. Importantly, further systematic electrochemical performance evaluation (including charge–discharge cycling at various rates and 200-cycle long-term cycling stability tests) confirmed that the introduction of this flame-retardant coating did not produce any detectable negative effects on capacity retention, Coulombic efficiency, or interfacial charge transfer process of the battery, demonstrating excellent compatibility between thermal safety protection and electrochemical performance. This multilevel synergistic flame-retardant mechanism, combined with its excellent compatibility with the battery’s electrochemical performance, makes the developed EP/ZIF-67@COF coating a highly promising thermal protection solution for next-generation high-safety, high-energy-density LIBs.
Abstract High-pressure phases are often unstable at ambient pressure and amorphize during decompression, making their direct recovery as crystalline materials difficult. Here, we demonstrate a route for synthesizing crystalline particles embedded in an amorphous matrix using an unstable high-pressure phase as a transient reaction medium. An amorphous CaSiO3 film deposited on a YAlO3 single-crystal substrate was treated at 15.6 GPa and 1200 °C. After recovery to ambient pressure and temperature, faceted (Ca,Y)(Si,Al)O3 perovskite-related particles were observed at the interface between the film and substrate. Structural and compositional analyses showed that the particles formed through reactive interdiffusion between the film and substrate and grew downward into the substrate while maintaining a crystallographic relationship with the YAlO3 substrate. The particles retained crystallinity at ambient pressure, whereas the surrounding CaSiO3-rich region became amorphous. These results indicate that transient high-pressure phase formation, interfacial reaction, and selective amorphization during decompression can be combined to produce faceted crystalline particles embedded in an amorphous matrix, a structure that is difficult to obtain by conventional crystal-growth methods.
Abstract Decoupling local packing effects from compositional and framework changes is crucial for understanding and designing high-performance birefringent crystals. Herein, two isocompositional hybrid antimony halides, α-[TMBEA]SbCl5 and β-[TMBEA]SbCl5, were obtained under solvothermal conditions by tuning the reaction concentration, providing a clean platform to evaluate the role of local aromatic overlap. Both phases contain closely related inorganic frameworks built from edge-sharing [Sb2Cl10]4– dimers but differ markedly in the aromatic contact modes of the [TMBEA]2+ cations. The α phase exhibits localized phenyl···phenyl π–π contacts, whereas the β phase features a more extended benzene/imidazole aromatic overlap. Independent gradient model based on Hirshfeld partition (IGMH) analyses reveal a broader and more continuous weak-interaction region in the β phase, consistent with its expanded aromatic stacking. Despite their similar optical band gaps, the experimental birefringence increases from 0.145 for α-[TMBEA]SbCl5 to 0.211 for β-[TMBEA]SbCl5 at 550 nm. First-principles calculations reproduce this trend and further reveal that the expanded aromatic overlap modulates the band-edge electronic states and strengthens through-space electronic coupling in the β phase. These findings demonstrate that local aromatic overlap modulation without compositional or framework changes can effectively amplify refractive-index anisotropy, offering a distinct design principle for hybrid birefringent materials.
Abstract Compound [Zn2(bpdc)2(BPTT)2]·BPTT (1) has been obtained by the reactions of Zn(NO3)2·6H2O, 4,4’-biphenyldicarboxylic acid (H2bpdc), and 2,5-bis(pyridin-4-yl)thiazolo[5,4-d]thiazole (BPTT), a rigid and planar π-conjugated ligand, under hydro(solvo)thermal conditions. Single-crystal X-ray diffraction analysis indicates that 1 adopts a two-dimensional layer structure with a (4,4) gridlike topology based on paddlewheel {Zn2(COO)4N2} secondary building units, where the two Zn(II) centers both show a {ZnO4N} square pyramidal geometry with a Zn···Zn separation of 2.9306(5) Å. Noteworthy, one free BPTT per formula, as a template, is located in the mesh of the (4,4)-grid layer. The BPTT template forms remarkable π···π stacking interactions (centroid-to-centroid distance is 3.639 Å) with the BPTT terminals in two neighboring layers and CH···N interactions (C···N distance is 3.578 Å) with the phenyl CH of the bpdc2– bridges. Compound 1 shows good thermal stability approaching 320 °C and is highly stable in various solvents and aqueous solutions with a wide range of pH values from 2 to 12. Upon excitation at 365 nm, 1 emits intense blue fluorescence centered at 471 nm in the solid state. Interestingly, 1 exhibits good reversibility and recyclability to quickly capture volatile iodine, leading to crystal color change and fluorescence quenching response up to 85%.
