CrystEngComm最新文献

The visualization of level 3 fingerprint features, such as pore size, spacing, and distribution, plays a crucial role in matching damaged latent fingerprints (LFPs). CsPbBr₃ microcrystals (MCs) show great potential for LFP visualization, but the use of organic surface passivation can deteriorate their fluorescence properties and reduce imaging quality. In this study, we developed CsPbBr₃ MCs with a Pb(OH)₂ passivation layer formed through a methylamine vapor phase transition, replacing the need for organic passivators. Thanks to the hydrophobic nature and hydrogen bonding properties of Pb(OH)₂, the CsPbBr₃ MCs demonstrate excellent structural and fluorescence properties, while also anchor effectively to amino acids. Beyond the pressure deficit mechanism, FT-IR analysis and theoretical calculations confirm that the –COOH groups in amino acids form hydrogen bonds with the OH groups of Pb(OH)₂, leading to the absorption of CsPbBr₃ MCs onto fingerprint ridges. This results in superior visualization of level 3 fingerprint details, offering new insights into the development of surfactant-free inorganic materials for fluorescence imaging.

Hybrid metal halides (HMHs) have attracted considerable attention from researchers exploring broadband luminescence materials due to their low cost and excellent photophysical properties. Although lots of structures have been developed by researchers based on monovalent and bivalent cations, the importance of trivalent cations in the design of low-dimensional HMH materials with broadband luminescence has been overlooked. In our study, we obtained two new 1D corrugated structures (MPEA)PbBr₅·H₂O (MPEA is 4-methyl-1-piperazineethanammonium) and (PEA)₂Pb₂Br₁₀·H₂O (PEA is 1-piperazineethanammonium) based on trivalent cations, which can efficiently emit yellow-white light emission with CIE color coordinates of (0.35, 0.42) and (0.42, 0.47) at room temperature with a photoluminescence quantum yield of 0.6% and 10.9%, respectively. Our research underscores the advantages of utilizing low flexible trivalent cations in the development of HMHs with outstanding broadband emission performance and provides novel insight into the design of advanced solid-state luminescent materials.

A large-scale synthesis of electrocatalysts with controllable composition and a surface atomic structure is crucial for practical applications. Herein, Pt–Pd hollow nanoparticles (HNs) were prepared using a facile microinjection strategy. Owing to their high-density nanopores, atomic steps and grain boundaries, the Pt–Pd HNs exhibit a superior catalytic activity for the methanol oxidation reaction (MOR) compared with commercial Pt black. Moreover, theoretical calculation proves that compared with the Pt and Pd structures, the Pt–Pd alloy structure possesses high anti-CO poisoning capability and a low energy barrier in the rate-limiting step, both of which are favorable for the MOR. This work proposes a strategy for large-scale preparation of hollow electrocatalysts with high catalytic activity, thus promoting practical application of direct methanol fuel cells (DMFCs).

Two new polyoxometalate-based metal–organic complexes (POMOCs), namely, H{Zn₂(Hpytty)₂[AlMo₆(OH)₆O₁₈](H₂O)₈}·6H₂O (1), H{Zn₂(Hpyttz)₂[AlMo₆(OH)₆O₁₈](H₂O)₈}·6H₂O (2) (H₂pytty = 3-(pyrazin-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl, H₂pyttz = 3-(pyrid-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl), were obtained under hydrothermal conditions using different N-rich triazole-derivatized ligands and they were characterized through powder X-ray diffraction (PXRD), single-crystal X-ray diffraction, and infrared spectroscopy. Both the title POMOCs show 2D supramolecular structures formed through hydrogen bonds, except that the [AlMo₆(OH)₆O₁₈]³⁻ anions in complex 2 are immobilized between the metal–organic units via coordination interaction. The capacitive performances of the carbon paper-based electrodes modified by complexes 1–2 were investigated, in which complex 2 achieved a larger specific capacitance of 1362 F g⁻¹ than that of 1 (1836 F g⁻¹) at a charge–discharge current density of 1 A g⁻¹. The enhancement in intramolecular bond strength is beneficial for improving the capacitance performance of complexes. In addition, after electrochemical conditioning with polyaniline, the electron–ion transfer rate, along with the pseudocapacitive activity of complexes 1–2 is also significantly improved.

We demonstrate the application of the ‘instantaneous pK’ approach to the molecular dynamics simulation of crystallite models exposed to an acidic solvent environment. For this, the bulk solution properties pH and pK are scrutinized into local aspects and effectively characterized for individual molecules of crystal faces, edges and steps, respectively. To illustrate this concept, we introduce two prototype cases: the acid-induced dissociation of i) calcite and ii) carbamazepine (CBZ, form III) drugs. We find acid-induced calcite dissociation follows a rather intuitive mechanism, namely the protonation of crystal edges/steps leading to ion-by-ion dissociation of HCO₃⁻ and Ca²⁺ species into water. In contrast, our simulations of CBZ solvation at pH = 3 and pH = 2, respectively, reveal a more complex dissolution behavior. The molecular crystals were found to accommodate a substantial degree of CBZ protonation without drug release to the solvent. Instead, the crystallite edges and corners are re-arranged in favor of a surprisingly stable core–shell structure featuring a CBZ core and a mixed CBZ/CBZH shell of +0.005 and +0.03 C m⁻² surface charge at pH = 3 and pH = 2, respectively. The resulting crystallite models are persistent and even more drastic acidity is needed to enable actual dissociation of CBZH into water.

A Tb-MOF complex based on triazine tricarboxylic acid ligands (2,4,6-tri(4-carboxylaniline)-1,3,5-triazine (H₃TATAB)) was constructed through the reaction of the rare earth metal Tb(III) and H₃TATAB. The complex featured a three-dimensional non-interpenetrating network structure constructed by the binuclear secondary building unit [Tb₂(CO₂)₆] and the H₃TATAB ligand. The complex exhibited excellent solvent stability, acid–base stability and thermal stability. Based on the fluorescence characteristics of the complex, it was found that the complex exhibited a sensitive fluorescence response and was recyclable for 7 kinds of nitroaromatic compounds (NACs) with different substituted groups, as well as heavy metal anions and cations (Cr₂O₇²⁻ and Fe³⁺). The fluorescence quenching behavior was preliminarily attributed to the synergistic effect of the CA and PET mechanisms.

Organic ammonium cations (A⁺) and inorganic [PbX₄]²⁻ (X: Cl, Br, I) anions bind to each other through electrostatic interactions, forming layered two-dimensional (2D) A₂PbX₄ hybrid perovskites. Thus, they dissociate in water. In contrast, charge-neutral organic amines (L) can covalently bind to metal M (M: Zn, Cd), forming M₂Q₂(L) (Q: S, Se, Te) hybrid II–VI semiconductors. We attempted to explore the optoelectronic properties of such a reported hybrid II–VI compound, Cd₂S₂(n-hexylamine), but surprisingly it did not form. Instead, the obtained product, referred to here as product-1, is a mixture of a new layered halide compound CdCl₂(n-hexylamine)₂ and CdS nanocrystals (NCs). The quantum confinement in ∼3 nm CdS NCs shows interesting optoelectronic properties, which were initially misinterpreted as signatures of a Cd₂S₂(n-hexylamine) quantum well structure. The obtained layered compound CdCl₂(n-hexylamine)₂ crystallizes in the P2₁/c space group. Each Cd²⁺ is coordinated with 4 equatorial Cl⁻ and two axial n-hexylamines, forming distorted octahedra that propagate in 2D, forming the layered structure. Note that the organic and inorganic components in CdCl₂(n-hexylamine)₂ are covalently bound (coordinate bonds), making the compound water-stable, unlike the electrostatically bound A₂PbX₄ perovskites. The covalent organic–inorganic bonding nature of the layered 2D hybrid halide compounds might be explored further for designing water-stable hybrid halide perovskite-like materials.

Cold crystallization occurs commonly in polymers but is rarely found in small molecular crystals. Here, we report the first photoluminescent second-order nonlinear optical molecular crystal with cold crystallization, which shows crystallization upon heating at 358 K as well as green photoluminescence emission and strong second harmonic generation response with intensity comparable to that of KH₂PO₄.

Second-harmonic generation using femtosecond pulses at 5.5 μm with a repetition rate of 80 MHz is demonstrated in ∼500 μm-thick layers of orientation-patterned GaAs_0.75P_0.25 grown using hydride vapor phase epitaxy on a structured GaAs template. The length of the sample used (∼500 μm) corresponds to only 4 quasi-phase matching periods of 8 coherence lengths.