Journal of Cluster Science最新文献

Borate-derived catalysts are attracting increasing attention as electrocatalysts for the oxygen reduction reaction (ORR). Herein, we report the synthesis of three novel metal-complex borates under mild conditions: [Ni(Ac)(bpy)₂]₂·[B₅O₆(OH)₄]·py (1, bpy = 2,2′-bipyridine, py = pyridine), [Co(Me₃tacn)]·[B₆O₇(OH)₆]·11H₂O (2, Me₃tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane), and [Ga(Cyclen)B₂O₃(OH)₂]·[B₅O₆(OH)₄] (3, Cyclen = 1,4,7,10-tetraazacyclododecane). Single-crystal X-ray diffraction reveals that compound 1 contains the [B₅O₆(OH)₄]⁻ cluster linked to Ni²⁺ complexes via hydrogen-bonds (H-Bs), whereas 2 and 3 feature covalent N-M-O-B hybrid linkages (M = Co, Ga) that enhance framework rigidity. All of the compounds are capable of self-assembling into either two-dimensional (2D) layered architectures or three-dimensional (3D) supramolecular frameworks with channels or voids. Following thermal treatment at controlled temperatures, the derived catalysts were evaluated for ORR performance in alkaline media. The half-wave potentials (E_1/2) reach optimal values at 750 °C for all series, with the best performance of 0.73 V for 1, 0.81 V for 2, and 0.78 V for 3. This work expands the library of borate-based materials and demonstrates their significant potential as cost-effective, non-precious-metal ORR electrocatalysts.

This work presents a systematic investigation of vanadium substitution in spinel NiCo₂O₄ as an effective strategy for enhancing NaBH₄ hydrolysis. Unlike conventional morphology-driven approaches, the improved catalytic performance is attributed to V-induced electronic structure modulation and defect engineering. A clear composition–activity relationship reveals an optimal doping level, highlighting the critical role of cation substitution in tuning catalytic behavior. The structures of the prepared catalysts NiCo₂O₄, Ni_0.95V_0.05Co₂O₄, NiCo_1.95V_0.05O₄ and NiCo_1.9V_0.1O₄ were fully investigated utilizing X-ray diffraction and Raman techniques. Rietveld refinement confirmed successful incorporation of V into the spinel lattice, accompanied by slight lattice contraction and local structural distortion. Raman spectroscopy revealed the emergence of a characteristic V–O stretching mode (~ 803 cm⁻¹) along with the disappearance of native spinel vibrations, indicating strong short-range disorder. Optical studies showed that V doping increases the band gap from 0.58 eV (pure) to 0.88–0.89 eV, correlating with reduced absorbance and modified defect states. Catalytic evaluation demonstrated that NiCo₁.₉₅V₀.₀₅O₄ achieving the highest hydrogen generation rate (~ 700 mL g⁻¹ min⁻¹). Kinetic analysis revealed a marked decrease in activation energy from 70.5 to 49.1 kJ mol⁻¹ upon V substitution. Remarkably, the activation entropy ΔS^‡ changes from positive (+ 24.44 J/K) to negative (− 43.73 J/K), signifying a mechanistic shift from a dissociative to an associative (Langmuir–Hinshelwood) pathway. Despite this change, the Gibbs free energy of activation remains nearly unchanged (~ 60 kJ mol⁻¹), indicating that V doping modifies the reaction kinetics without altering the thermodynamic feasibility. These results establish V-substituted NiCo₂O₄ as a promising, earth-abundant catalyst for hydrogen generation and demonstrate that cation substitution can fundamentally alter reaction mechanisms beyond simple surface area or conductivity improvements.

A systematic theoretical investigation on the geometric structures, infrared spectroscopic characteristics, electronic properties, chemical bonding nature, and thermodynamic stabilities of anionic boron clusters B_n⁻ spanning the size range from n = 2 to n = 40 has been performed utilizing a tiered computational protocol integrating global minimum search, density functional theory (DFT) and high-level CCSD(T) calculations. Wavefunction analyses, including AdNDP, NICS, QTAIM, ELF, IRI, and RDG/NCI analyses, were conducted on representative clusters to unravel the intrinsic chemical bonding features. Simulated infrared spectra provide characteristic fingerprint signals for structural identification, while canonical molecular orbital calculations reveal the evolution of HOMO-LUMO energy gaps with cluster size. The results demonstrate that most anionic boron clusters prefer planar or quasi-planar configurations governed by delocalized σ and π bonding, whereas some clusters have a structural transition from two-dimensional (2D) planar motifs to three-dimensional (3D) cage architectures. Distinct infrared absorption peaks are distributed in the range of 134–1773 cm⁻¹, showing size-dependent spectral features. Chemical bonding analysis manifests the prevalence of multi-center delocalized bonds and dual aromaticity in these boron clusters, accounting for their high structural stability. Thermodynamic calculations corroborate that the formation of B_n⁻ clusters is exergonic and exothermic, indicating the spontaneous nature of forming these clusters under standard conditions. This work provides a holistic understanding of the size-dependent structural evolution, spectroscopic fingerprints, and bonding chemistry of anionic boron clusters, laying a theoretical foundation for experimental characterization and functional application of boron-based nanoclusters and two-dimensional borophene materials.

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In this study, we introduce a new probe, (Rh-Ph)₄-TPE, created by attaching four rhodamine groups to a tetraphenylethene ring. This versatile compound is notable for several reasons. First, it emits a bright fluorescent signal upon detection of aluminum ions (Al³⁺), even at concentrations as low as 287 nM. Furthermore, when both Al³⁺ and fluoride ions (F⁻) are present, the fluorescence is quenched, enabling the probe to detect fluoride at levels as low as 1.04 µM. Beyond its impressive sensing capabilities, (Rh-Ph)₄-TPE can function as a molecular “memory” device. In practice, we found that (Rh-Ph)₄-TPE rapidly detects Al³⁺ and F⁻ ions using simple filter paper strips, and the results can be analyzed with a smartphone camera and RGB color analysis. In biological experiments with MCF-7 cancer cells, the compound demonstrated dose-dependent cytotoxic activity (IC₅₀ of 529.76 µg/mL) and enabled visualization of aluminum ions within cells via fluorescence imaging. We also tested the probe in living Daphnia magna (water fleas), where it produced a distinct green glow in the presence of Al³⁺, confirming its selectivity. Overall, our findings suggest that (Rh-Ph)₄-TPE could be a useful tool for environmental monitoring, biological imaging, and potentially for cancer diagnostics and therapy.

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The electrophilic iodination of 1,7-dicarba-closo-dodecaborane (1,7-C₂B₁₀H₁₂, meta-carborane) has been systematically investigated as a function of the stoichiometric ratios of iodine (I₂) and aluminum chloride (AlCl₃) in dichloromethane. Under stoichiometric conditions (1.0 equivalent of AlCl₃ relative to the carborane), the reaction outcome is determined by the amount of iodine used. With one equivalent of I₂ (1 : 1 : 1 ratio of meta-carborane/I₂/AlCl₃), the monoiodo derivative 9-I-1,7-C₂B₁₀H₁₁ was obtained selectively in high yield within 2 h. With two equivalents of I₂ (1 : 2 : 1 ratio), the reaction proceeded further and after refluxing and prolonged stirring, the diiodo derivative 9,10-I₂-1,7-C₂B₁₀H₁₀ was selectively formed. Interestingly, when the iodination was carried out under catalytic AlCl₃ loadings (0.1 equivalent), the formation of by-products was observed, including an unusual methylene-bridged dimer µ-9,9’-СН₂-µ-10,10’-СН₂-(1,7-С₂В₁₀Н₁₀)₂ and the methylated derivative 5-Me-9,10-I₂-1,7-C₂B₁₀H₉. A control experiment revealed that the methylene-bridged dimer is also formed in the absence of iodine when meta-carborane is refluxed with AlCl₃ in CH₂Cl₂, indicating that this side reaction is a separate process that does not require iodination. The individual molecular structures of µ-9,9’-СН₂-µ-10,10’-СН₂-(1,7-С₂В₁₀Н₁₀)₂ and 5-Me-9,10-I₂-1,7-C₂B₁₀H₉, as well as the structure of solid solution of methylated derivative with diiodo derivative 9,10-I₂-1,7-C₂B₁₀H₁₀, were established by single-crystal X-ray diffraction analysis.

Graphical Abstract

Lattice strain is one of the most significant structural parameters in nanostructures; however, the lack of specified techniques makes its determination very difficult. Due to its simplicity and easy data processing, the X-ray diffraction (XRD) technique is widely adopted for the determination of crystallite size from peak broadening. Even though the dependence of lattice strain on peak broadening has been proven but use of peak broadening for the estimation of this parameter is not very popular. Generally, the pseudo-Voigt peak-profile function, Williamson-Hall (W-H), and Halder-Wagner (H-W) methods are widely utilized. Herein, W-H and H-W approaches are studied to provide an understanding of lattice strain behaviour. For this work, zinc ferrite nanostructures are synthesized using different chemical methods to investigate the size/synthesis dependent behaviour of strain. XRD patterns obtained on these synthesized materials exhibit the presence of a cubic spinel phase. These materials are further investigated using Fourier transform infrared spectroscopy to study the characteristic bands associated with the spinel phase. Lattice strain values of these nanostructures, using W-H and H-W approaches generally differ; however, these values exhibit similar trends with size or synthesis parameters. Values estimated from H-W methods may be considered more reliable as the correlation coefficient is close to 1. Further magnetic measurements reveal that these materials show paramagnetic or superparamagnetic behaviour.

Drawing inspiration from nature offers possibilities not only for designing next-generation aircraft or high-speed trains on a macro scale, but also for designing nano-network structures or nanofiber structures for functional applications on a very small scale. This study involved experiments and analyses to determine the process conditions under which nanofiber structures, inspired by Steiner Minimal Trees found in nature, particularly in soap bubbles and/or spider webs, can be developed. Simultaneously, the similarities and differences between the obtained nanofiber structures and those found in previous studies were discussed, and theoretical inferences were made regarding their potential functional applications. Nanofibers obtained by applying two different polymers and process conditions were analyzed and colored using the Python language, and their Steiner Minimal Tree compatibility was tested. Accordingly, it was determined that the nanofibers most suitable for the Steiner Minimal Tree structure are those produced in polylactic acid polymer under specified conditions. This study presents a preliminary Python-based framework for comparing bridge- and cycle-associated features in two-dimensional SEM projections of selected nanofiber networks. The work does not optimize polymer formulations or electrospinning parameters and does not directly measure drug-delivery performance; rather, it establishes topology-based hypotheses for subsequent experimental testing.

Alectinib hydrochloride (ALC) is approved for the treatment of non-small cell lung cancer (NSCLC) patients with Anaplastic Lymphoma Kinase (ALK) genetic mutations. Meanwhile, the limited bioavailability of around 37% in the fed condition and only about 11% in the fasted condition suggests a prominent fast-fed effect on oral bioavailability that curbs its clinical potential. The fast-fed variation results in sub-optimal therapeutic efficacy, which affects the design of the dose and dosage regimen for the physicians. To mitigate all these pitfalls, in the present investigation, we have developed robust and reproducible ALC-laden SNEDDS using an I-optimal mixture design. Further, emulsification studies demonstrated spherical globules of size 67.14 ± 18.57 nm, PDI of 0.189 ± 0.07, with % transmittance of 95.97 ± 4.18%. The in vitro dissolution profiles in fasted and fed biorelevant media were improved and similar, thereby reducing fast-fed variability. Additionally, ALC-SNEDDS demonstrated improved cytotoxic (3.49-fold), ROS generation (2.11-fold), and apoptosis induction potential (1.22-fold) in comparison to pristine ALC against A549 cells. In vivo intestinal permeation study reported increased fluorescence intensity of C6-SNEDDS in intestinal cross-sections, confirming enhanced in vivo intestinal permeability. Moreover, an improved pharmacokinetic profile in terms of Cmax_fast/fed (0.97) and AUC_fast/fed (0.84), which is closer to 1 irrespective of prandial state, indicates attenuation in fast-fed variability. 

Graphical Abstract

Identifying the geometric structures of zinc clusters is of great importance in future nanotechnologies due to their superior properties. However, some ground-state structures are still in debate, because the experiments and calculations are not performed at the same temperature. In this work, first-principles calculations show that Zn_n (n = 2-20) clusters evolved from tetrahedral to capped tri-prism and densely packed growth modes, and the ground states of Zn_n (n=4, 10, 15) are the basic units. Correspondingly, these basic units usually have higher energetic and thermal stability. Characteristic bond length changes in ab initio molecular dynamics (MD) simulations confirm that the initial melting process begins from the bond in the basic units, due to their weaker bonding. This work emphasizes the thermal stability concept in theoretical calculations, which should be a necessary supplement in cluster science.

By using Monte Carlo simulations, the magnetic properties of a trilayer Kagome nanostructure (TKN) are studied according to the mixed-spin (7/2, 1) Blume-Capel model. From the simulation data, it is observed that a quite complicated magnetization profile consisting of eight magnetization plateaus is observed due to quantization of the system’s magnetic states. The multi-step magnetization phenomenon results from the interplay between crystal-field and exchange interactions, giving rise to three critical fields and a saturation field that define different stable states of the system successively. The discussion of the effects of the model parameters on the behavior of the system shows that the crystal field parameter contributes to the stability of magnetization plateaus through improving their rigidity; in contrast, the exchange interaction parameters contribute to lowering their stability and decreasing their number. Additionally, an increase in temperature leads to a smooth magnetization profile since higher temperatures weaken the stability of the magnetization plateaus.