CrystEngComm最新文献

Metal–organic framework (MOF)-derived materials, such as transition metal sulfides (TMSs), are attracting much attention for their high theoretical specific capacity as anodes for lithium-ion batteries (LIBs). Herein, a core–shell-structured anode comprising a Cu₉S₅ core and a Co₃S₄ shell embedded in nitrogen-doped carbon (NC) (Cu₉S₅/NC@Co₃S₄/NC) has been developed by combining the calcination and sulphuration treatments of the Cu-BTC@ZIF-67 precursor. In this composite, both Cu₉S₅ and Co₃S₄ exhibit high electrochemical reaction activities. The sulfides were combined in situ with the porous nitrogen-doped carbon to realize an integrated structure, which efficiently alleviated their aggregation and volume variations during the charging and discharging processes. The good reactivity and structural stability of the Cu₉S₅/NC@Co₃S₄/NC anode led to a high capacity (1067.3 mAh g⁻¹ at 0.1 A g⁻¹), even at 5 A g⁻¹. The Cu₉S₅/NC@Co₃S₄/NC anode showed negligible capacity degradation and maintained a capacity of 500 mAh g⁻¹ after 500 cycles. This study proposes an effective strategy for engineering high-performance sulfide-based anodes for LIBs, as evidenced by their superior electrochemical performance.

The combustion efficacy of propellants is crucial to the overall performance of rockets and missiles. Conventional propellant combustion catalysts suffer from toxicity and severe environmental pollution. To meet the demand for new green and non-toxic combustion catalysts, we synthesized three novel bismuth-based combustion catalysts, namely, [Bi₂(DHBQDC)(OX)₂(DMF)₆] 1, [Bi(BPSA)(PHON)(Ph)]·3DMF 2, and [BiO(TFPHA)H₂O]·H₂O 3, in this study. The structures of the catalysts were determined by single-crystal X-ray diffraction (SCXRD), and their thermal stability was investigated. Results demonstrated that all three catalysts exhibited excellent thermal stability, with the decomposition temperature of their organic frameworks exceeding 200 °C. In addition, differential scanning calorimetry and thermogravimetry were employed to study the thermal decomposition performance of the catalyst–RDX mixed systems. The introduction of these catalysts promoted the decomposition of RDX, leading to a reduction in the decomposition temperature of the systems to varying degrees and a decrease in the activation energy of the reaction. A high-speed camera was used to study the flame combustion performance of the mixed catalyst systems with RDX + NC/NG, which further confirmed the catalytic performance of various catalysts.

Metal phosphonate frameworks (MPFs) are emerging as highly effective catalysts for the transformation of CO₂ into cyclic carbonates. These materials combine the structural robustness of inorganic solids with the tunability of organic linkers, enabling efficient catalysis with exceptional stability and recyclability. The synergy between the Lewis metal centers and phosphonate-derived Brønsted acidity enables efficient activation of both CO₂ and epoxide substrates within confined pores. This review critically examines the recent progress in the development of MPFs for CO₂ conversion, highlighting their structural, catalytic, and functional advantages over traditional MOFs. We also address the limitations of MPFs, particularly in terms of scalability, stability, and economic feasibility. Future directions will focus on developing greener and more scalable synthesis methods, as well as the integration of MPFs into more efficient and sustainable CO₂ utilization processes.

A α-Bi₂O₃/α-Bi₂O₃ homojunction composed of α-Bi₂O₃ nanosheets growing on α-Bi₂O₃ nanorods is developed by a facile room-temperature preparation method; this homojunction exhibits significantly high photocatalytic performance for reducing the heavy metal Cr(VI). The degradation of a 50 mg L^–1 Cr(VI) solution under simulated sunlight takes only 6 min, and the apparent rate constant value reaches 0.657 min⁻¹, which is 9.5 times that achieved with the α-Bi₂O₃ nanorods. Photocurrent time curves, electrochemical impedance spectroscopy (EIS) and PL emission spectra prove that the formation of the α-Bi₂O₃/α-Bi₂O₃ homojunction improves the transfer and separation of photogenerated e-h pairs. The average fluorescence lifetime of the α-Bi₂O₃/α-Bi₂O₃ homojunction is 5.1998 ns, which is longer than that of pure α-Bi₂O₃. The results of in situ irradiated X-ray photoelectron spectroscopy (ex-XPS) and the KPFM-based surface photovoltage (SPV) prove that the photoelectrons transfer from the α-Bi₂O₃ nanorods to the α-Bi₂O₃ nanosheet via the interface in light. These findings provide a general and simple synthetic method for preparing homojunction photocatalysts, which has good potential for a broad range of applications.

Rational creation of efficient, stable, and economical bifunctional electrocatalysts is highly desired for water splitting. A CoMoS₂/NiSe₂ heterostructure electrocatalyst supported on nickel foam (NF) was successfully synthesized using a hydrothermal method. The distinctive chrysanthemum-like hierarchical architecture of CoMoS₂/NiSe₂ not only offers numerous accessible active sites but also enhances electrolyte diffusion and charge transfer. In a 1.0 M KOH electrolyte, the overpotentials for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at 10 mA cm⁻² are 47 mV and 246 mV, respectively, demonstrating remarkable stability over 100 hours and excellent turnover frequency. X-ray photoelectron spectroscopy (XPS) analysis indicated that the formation of the CoMoS₂/NiSe₂ heterojunction facilitates interfacial electron transfer, thereby optimizing the electronic structure and augmenting the intrinsic catalytic activity. This study presents a viable method for the design of high-performance heterostructured electrocatalysts for efficient water electrolysis through interface engineering and electronic structure modulation.

This work presents the synthesis, structural elucidation via X-ray diffraction, and density functional theory (DFT) investigation of three novel ligands based on deferiprone: maltol-TAU (3), maltol-histidine (4), and maltol-histamine (5), derived from taurine, histidine, and histamine, respectively. Additionally, the copper(II) complex of the histamine derivative, [Cu(maltol-HISTA)₂(H₂O)₂]·2H₂O·2HCl (6), was synthesized and characterized. In the solid state, the supramolecular architectures of ligands 3–5 and complex 6 are primarily stabilized by hydrogen bonding and $pi$-stacking interactions. Theoretical modeling corroborated these observations, confirming that compounds 3, 4, and 5 possess protonated imidazole rings accompanied by sulfonate, carboxylate, and chloride counter-ions, respectively. A distinct conformational variation was observed regarding ring orientation: the hydroxypyridinone and imidazole rings are positioned nearly orthogonally in 4, whereas they adopt a parallel arrangement in 5. DFT calculations were further employed to analyze specific supramolecular assemblies, with a focus on the structural influence of co-crystallized water molecules. To rigorously characterize the H-bonding and non-covalent interactions, quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) plot analyses were utilized, providing detailed insight into the electronic and structural features of these potential coordination chemistry candidates.

In this research, a minute quantity of Ce was introduced into a NaY framework via the hydrothermal method, followed by gradient temperature calcination to acquire a series of Ce-NaY samples. Subsequently, a multi-dimensional characterization method was adopted. This method mainly included HRTEM analysis, XPRD structure refinement, Py-FTIR spectroscopy, in situ IR-catalytic conversion (using cyclohexene as the probe), and microreactor hydrogen transfer activity assessment. The aim was to precisely trace the location of the low-content Ce within the framework and uncover its regulatory mechanism for the “precursor” of FCC carbon deposition. The results indicated that the Ce_0.01-550Y sample achieved the lowest carbon deposition while maintaining the highest cyclohexane yield. Its excellent performance stemmed from the fine matching and synergistic effect of the Brønsted (B) acid and Lewis (L) acid densities. The findings demonstrate that the precise confinement of rare earth ions to designated sites within the SOD cages can effectively suppress the formation and evolution of carbon precursors (cyclohexene carbocation), thereby blocking the initiation pathway of carbon deposition and reducing its selectivity.

A new series of donor–acceptor fluorescence molecules based on a dimethoxy-substituted triphenylamine donor and different acceptors (malononitrile, ethyl cyanoacetate, cyanoacetic acid, cyanoacetamide, indanedione and dimethyl barbituric acid) was synthesized and investigated for their solid-state structural assembly and tunable and switchable fluorescence. Single-crystal analysis revealed twisted non-planar molecular conformations with acceptor-dependent structural organization and intermolecular interactions. DMT-MN, DMT-ECA and DMT-ID displayed intermolecular interaction-mediated dimer formation with opposite molecular orientations. DMT-CAA and DMT-BA showed network structure, whereas DMT-CA exhibited complementary amide H-bonding in the crystal lattice. Solid-state fluorescence studies showed blue-shifted emission for DMT-CA (λ_max = 532 nm), and DMT-ID displayed red-shifted fluorescence at 630 nm. DMT-MN exhibited the highest solid-state fluorescence efficiency of 16.2%. Computational studies supported the fluorescence tuning by showing acceptor group-dependent optical band gaps. It also suggested locally excited (LE) state emission in DMT-CA and charge transfer (CT) state emission in DMT-ID. DMT-ECA exhibited reversible temperature-dependent off–on fluorescence switching. The fluorescence intensity was strongly reduced by heating and reversed to the initial state upon cooling. The reversible thermofluorochromism of DMT-ECA was further supported by a clear phase transition between 100 and 130 °C. PXRD studies confirmed the structural stability of DMT-ECA before and after heating. DMT-MN showed crystallization solvent-dependent tunable fluorescence. The as-synthesized powder and crystals grown from ethyl acetate showed fluorescence at 554 nm, whereas crystals obtained from DCM–EtOH showed fluorescence at 590 nm. However, single-crystal analysis did not show any polymorphism and exhibited only slight variations in molecular conformations. Thus, the current work explored the structure–property relationship of new donor–acceptor molecules and elucidated the impact of molecular structure for achieving thermofluorochromism.

A unique lead perrhenate crown ether complex, [Pb(12-crown-4)(H₂O)(ReO₄)₂], exhibits an incommensurately modulated crystal structure at 101 K. In this (3 + 1)D superspace description, the ReO₄⁻ tetrahedra undergo continuous rotation. Describing their continuous rotation required introducing several constraints into the Legendre polynomials describing the displacive modulation of these atoms. At 296 K, the rotation of these tetrahedra is characterized by jumps between certain “stationary” positions. The average structure is monoclinic, P2₁/c with Z = 4, and can be described as comprising [Pb(C₈H₁₆O₄)(ReO₄)₂(H₂O)] ribbons. One half of the Pb²⁺ coordination sphere is occupied by the crown ether ligand, while the other is occupied by the oxygen atoms of water molecules and the perrhenate groups. The latter play two crystallographic roles: one bridging the PbO₈ polyhedra and the other acting as a terminal ligand with a very rare monodentate (κ¹) coordination. This is probably the reason for the nearly free rotation of these terminal ReO₄ groups along the Pb–O–Re axis. The structural chemistry of lead crown ether complexes, even those with relatively simple counteranions, is expected to yield a wide variety of unique and complex structures.

In recent years, rare earth ion doping has enhanced the luminescence performance of perovskite quantum dot (PQD) glass, but the enhancement mechanism caused by internal energy transfer deserves further study. In this work, a series of CsPbBr₃ PQDs doped with different concentrations of Tb³⁺ ions was prepared in a germanium borate glass matrix by the traditional melt quenching method and a heat treatment process. The experimental results indicate that after introducing Tb³⁺ ions into the PQD glass, the photoluminescence intensity was significantly enhanced by 11 times, and the photoluminescence quantum yield increased from 14.8% to 46.1%. The occurrence of this phenomenon can be attributed not only to the role of Tb³⁺ as a nucleating agent in PQD glass, which facilitates the formation of more small-sized CsPbBr₃, but also to its ability to replace Pb²⁺, thereby alleviating lattice distortion and passivating defects. Moreover, the core mechanism lies in the energy transfer process between Tb³⁺ and CsPbBr₃. It has been verified that there is not only a radiative photon reabsorption process in which Tb³⁺ releases photons that are absorbed by CsPbBr₃ but also a Förster resonance energy transfer process in which Tb³⁺ directly transfers energy to CsPbBr₃ in a non-radiative form. Finally, considering the differing thermal attenuation rates of Tb³⁺ and CsPbBr₃ in glass, a temperature-dependent luminescence color-tuning strategy is proposed, which has potential application value in the field of temperature sensing.