CrystEngComm最新文献

Continuous production of the 1 : 1 acetazolamide (ACZ) : p-aminobenzoic acid (PABA) cocrystal was achieved via cooling cocrystallization in a tubular slug flow crystallizer, under conditions mimicking batch cooling crystallization. Regulating the ACZ : PABA feed ratio was the critical parameter that yielded pure cocrystals within 15 minutes of residence time.

The halogen bond (XB) is denoted as R–X⋯Y, where the halogen atom X is covalently linked to the R group and possesses a potentially electrophilic region on its electrostatic potential surface, while Y is an anionic/neutral species with at least one nucleophilic centre that may donate electron density (an XB acceptor). For more than two decades, scientists have worked to clarify the nature of halogen bonds in order to advance their applications. Halogen bond finds utility in the absorption of drugs and their delivery to the target tissues, and thyroid hormones T3 and T4 serve as XB donors in biomolecular systems. This concept has also been explored in organocatalysis, supramolecular chemistry as well as in crystal engineering. There are only a few reports of metal-mediated transformation via XB. In fact, there are only few cases of XB formation to metal halides where some other ligands behave as Lewis bases in the complexes. Ligand exchange via the formation of a halogen bond (XB) has been observed only in a few cases, but this finding is very useful for the development of M–X bond activation processes that are stimulated by halogen-bond formation in certain intermediate steps. In this perspective article, we summarize the key developments in this field, where the role of XB in metal-halogen bond activation with concomitant substitution is discussed with some details on the theoretical mechanistic insights and relevant experimental evidences.

Recently, the rich energy level structure of Ln³⁺ ions has introduced new diversity into the double perovskite material, making it a research hotspot. The Sb³⁺/Ho³⁺ co-doped Cs₂KGdCl₆ double perovskite was synthesized using a simple dissolve–dry method in this study, which exhibits not only a broadband green emission from self-trapped excitons (STEs) but also a characteristic red emission from the f–f transitions of Ho³⁺. Experimental results confirmed effective energy transfer channels between STEs and Ho³⁺, with Sb³⁺ sensitization significantly enhancing the Ho³⁺ emission intensity. Further introduction of Yb³⁺ achieves dual-mode multicolor emission including down-shifting (DS) and up-conversion (UC). Under 315 nm and 450 nm excitation, the obtained material displays blue green and red emissions, respectively. Under 980 nm near-infrared excitation, the emission color changes from pale yellow to orange red with increasing laser power. A compound fluorescent anti-counterfeiting label was fabricated based on 1%Sb³⁺/13%Ho³⁺/35% Yb³⁺ co-doped Cs₂KGdCl₆. Finally, Tm³⁺ doping enabled efficient UC white light emission. This work provides new insights for achieving white-light emission and anti-counterfeiting applications via metal ion doping in lead-free double perovskites.

Angstrom-level pore regulation in a triazolate-based MOF is achieved through a reorientation of triazolate rings induced by amino functionalization. The resulting pore contraction effectively suppresses CH₄ diffusion while preserving CO₂ transport, leading to markedly enhanced CO₂/CH₄ selectivity.

We present the results of a study on Raman and high-resolution luminescence spectroscopy of Ce³⁺-doped Tb₃Al₅O₁₂ single crystalline films (SCFs) grown by the liquid phase epitaxy (LPE) method onto Y₃Al₅O₁₂ and Gd₃Al_2.5Ga_2.5O₁₂ single crystal (SC) substrates. The Ce³⁺-doped Tb₃Al₅O₁₂ films exhibit a strong Ce³⁺ 5d–4f emission band centred at 560 nm when excited around 488 nm in the vicinity of the 4f–5d absorption band of Ce³⁺ and the 4f–4f absorption bands of Tb³⁺ ions in the visible range. To avoid overlapping with this luminescence, Raman spectra were recorded using a 785 nm excitation wavelength. The lattice mismatch between the Tb₃Al₅O₁₂:Ce films and the Y₃Al₅O₁₂ and Gd₃Al_2.5Ga_2.5O₁₂ substrates was found to be +0.53% and −1.32%, respectively. The film grown on the Gd₃Al_2.5Ga_2.5O₁₂ substrate exhibits negative and higher residual stress compared to its counterpart grown onto the Y₃Al₅O₁₂ substrate. The observed shifts in the positions of the Raman modes for the two epitaxial structures correlate with the differences in lattice constants between the films and their respective substrates. High-resolution luminescence spectra recorded at 488 nm and 785 nm excitation wavelengths reveal 5d–4f and 4f–4f electronic transitions of Ce³⁺ ions and lanthanide trace impurities, respectively.

Rare earth elements are critical raw materials for modern technologies and the global shift toward sustainable energy. Yet, their extraction and separation remain environmentally challenging due to complex geochemical behavior and limited understanding of mineral formation mechanisms. This study integrates recent experimental advances to elucidate the fundamental processes controlling the crystallization and transformation of REE-bearing carbonates and phosphates. REE carbonate formation from aqueous solutions follows a non-classical pathway involving amorphous precursors and metastable intermediates that gradually transform into stable hydroxycarbonates such as kozoite and bastnäsite. The kinetics, polymorph selection, and resulting morphologies are governed by the ionic potentials of the REE³⁺ cations, temperature, and dehydration dynamics. Mineral replacement reactions between REE-bearing fluids and common host minerals like carbonates (calcite, aragonite, dolomite, siderite) and phosphates (vivianite), proceed through coupled dissolution–precipitation, producing pseudomorphic textures. The extent and texture of these transformations are controlled by epitaxial relationships, porosity generation, and local equilibrium conditions. Redox-driven processes, particularly Ce³⁺–Ce⁴⁺ and Fe²⁺–Fe³⁺ oxidation in siderite and vivianite, promote formation of secondary oxides (cerianite, hematite) that influence REE mobility and sequestration. In fluorine-bearing environments, transient fluocerite stabilizes and subsequently transforms epitaxially into bastnäsite, demonstrating the chemical and structural controls governing ore mineralization. Finally, we explore sustainable REE recovery using waste-derived sorbents such as eggshell calcite. Experiments show temperature-dependent REE uptake and complex phase transformations, offering insights for circular-economy approaches to resource recycling. Collectively, these results establish a unified mechanistic framework linking REE mineral formation, transformation, and recovery. By bridging natural ore-forming processes with green chemistry strategies, this study advances understanding of REE geochemistry and supports the development of environmentally sustainable extraction and recycling technologies.

Herein we report on the host ability of di-(9-(p-chlorophenyl)xanthen-9-yl) peroxide (H) for the four isomers of the C₈H₁₀ aromatic crude oil fraction, namely o-, m- and p-xylene (o-Xy, m-Xy and p-Xy) and ethylbenzene (EB). Crystallization of H from each of these solvents revealed that both o-Xy and p-Xy formed complexes with this host species, while m-Xy and EB were not enclathrated. ¹H-NMR spectroscopic analysis of the resultant solids demonstrated that the host : guest (H : G) ratios for the two complexes were 1 : 1 and 4 : 1, respectively. The host compound was subsequently crystallized from various equimolar and binary non-equimolar mixtures of these isomers, and a remarkable selectivity for o-Xy was observed. In fact, it was demonstrated that H has the ability to separate the 20/80 and 40/60 o-Xy/m-Xy as well as the 40/60, 50/50, 60/40 and 80/20 o-Xy/EB mixtures: extremely high selectivity coefficients (K), in favour of o-Xy, were calculated in each of these instances. This is an extraordinary finding given the difficulty of separating such mixtures by the more conventional fractional distillations owing to the comparable physical properties of these guest solvents. The two complexes as well as guest-free H were subjected to both single crystal X-ray diffraction and thermal analyses. The former technique demonstrated that the preferred guest species, o-Xy, was accommodated in the complex in discrete cavities, while disfavoured p-Xy experienced wide open channel occupation. This observation explains the affinity of H for the ortho isomer relative to p-Xy when guests competed, since enhanced thermal stabilities of complexes are associated with the former type of accommodation (isolated voids). Furthermore, o-Xy experienced nonclassical H-bonding with the host molecule, an interaction type not observed in the case of the para isomer. Additionally, from the thermal experiments, the p-Xy-containing inclusion compound, plausibly as a result of its retention in wide open channels, possessed an extremely low thermal stability at ambient temperature and pressure, while the complex with o-Xy, which occupied discrete cavities, was stable in analogous conditions.

Waxes within the leaf cuticle, the outermost layer of the plant leaf, play a defining role as a transpiration barrier and also serve as an important target for agrochemical interventions for crop protection. A prevailing model for this behaviour is the role of wax ‘bricks’ in building the diffusion barrier. This review brings together crystallographic and microstructural research to highlight the variety of crystalline, disordered, and amorphous structural features known in waxes. We trace two predominant research routes applied to leaf waxes: one directed at simplified waxes but with highly detailed descriptions of molecular packing and a second focused on the diffusion characteristics of the complex system of the cuticle and its multicomponent wax compositions. Bringing these routes together will develop sufficiently complex but tractable structural models for waxes, often dominated by a single or a few components in common crop plants. A complete description of leaf wax function will enable ways to control diffusion through the development of targeted interventions for drought tolerance.

The formation of a crystal structure from molecules that self-assemble in solution until the final crystal formation constitutes the construction of a supramolecular structure. In this process, molecules interact to form a complex system. These self-organized systems, characterized as open, can organize spontaneously when exposed to a given gradient. Because this gradient is information-neutral, the organization emerges from within the system, resulting in “emergent” properties that are unpredictable and irreducible. This highlight review provides a concise guide to understanding the fundamentals of a holistic approach, where the emergent properties of the crystal system are considered in the study. It emphasizes that interactions between molecules result from the interaction of their surfaces with complementary electrostatic potentials; regions of high negative electrostatic potential on one molecule interact with regions of high positive electrostatic potential on another. According to the non-classical theory of nucleation, these complementary interactions between molecules lead to the formation of the “first building blocks” while still in solution. As the process progresses, interactions among the more robust and cooperative building blocks self-organize to form the three-dimensional supramolecular structure. Understanding the complexity inherent in the formation of supramolecular structures poses a major challenge, beginning with the difficulty of delimiting a portion of the supramolecular system that represents all the interactions existing in the crystal. This study considers a demarcation based on the “supramolecular cluster” formed by a central molecule (M1) and its neighbors (MN) in the first coordination sphere. Thus, the supramolecular cluster is conceptualized as the smallest portion of the crystal that contains all the intermolecular interactions present in the system. Through the concept of retrocrystallization, it is possible to identify the main building blocks of the crystal. Utilizing the energetic and topological data of the intermolecular interactions, we developed proposals for crystallization mechanisms. Some steps in these mechanisms are confirmed by ¹H NMR and mass spectrometry, which identify initial nucleation blocks still in solution. In this highlight review, we present proposed crystallization mechanisms for more than 200 organic compounds with diverse molecular structures, identifying at least nine main crystallization mechanisms.

We report on a new tetranuclear lead(II) complex [Pb₄L₄(NO₂)₂(MeOH)₂](ClO₄)₂ (1), which was obtained by reacting an aqueous mixture of Pb(ClO₄)₂·3H₂O and NaNO₂ with a methanolic solution of N′-(amino(pyrazin-2-yl)methylene)thiosemicarbazide (HL), yielding orange prism-like crystals suitable for single-crystal X-ray diffraction. Elemental analysis confirmed the composition of the isolated solid, while the FTIR and ¹H NMR spectroscopy data supported the structural characterization. The parent organic ligand was found to be deprotonated to L under the applied synthetic procedure. The crystal structure of complex 1 revealed a centrosymmetric tetranuclear [Pb₄L₄(NO₂)₂(MeOH)₂]²⁺ cation, comprising two distinct Pb²⁺ cations, which are N,N′,S-chelated by one monodeprotonated ligand L. The DFT calculations, combined with QTAIM analysis, suggest that the tetranuclear core is best described as a self-assembled dimer of dinuclear units linked by Pb⋯N tetrel bonds. The substantial stability of this assembly is rationalized by the MEP surface, which reveals that the ClO₄⁻ anions act as a supramolecular “glue”, bridging the cationic units via a synergistic combination of tetrel bonds and electrostatically driven N–H⋯O hydrogen bonds. Furthermore, ELF and RDG analyses unequivocally confirm the σ-hole nature of the intra- and intermolecular Pb⋯S tetrel interactions. These tetranuclear cations further self-assemble into 1D supramolecular chains through Pb⋯S and Pb⋯O_nitrite tetrel bonds. The ClO₄⁻ anions “glue” these chains via Pb⋯O tetrel bonds. The coordination polyhedra of the two crystallographically independent Pb²⁺ cations are best described as capped cube J8 or spherical-relaxed capped cube, and spherical capped square antiprism. The structure of complex 1 is reinforced by a rich variety of N–H⋯N, N–H⋯O and O–H⋯O hydrogen bonds involving NH₂ and methanol OH hydrogen atoms, forming 2D supramolecular layers.