Crystal Growth & Design最新文献

Converting chemically inert and thermodynamically stable CO₂ into value added products remains a fundamental challenge associated with carbon neutrality and long-term energy security. In this work, we present a chemically resilient nanoporous framework, {[Y(HPPDDC)(DMF)₂]·3DMF·4H₂O}_n (NUC-190), constructed through the self-assembly of a deliberately engineered, structure-oriented linker, 4,4′-(4-phenylpyridine-2,6-diyl)diisophthalic acid (H₄PPDDC). Cooperative organization between dinuclear [Y₂(COO)₆] clusters and the organic building unit gives rise to a two-dimensional layered motif, [Y(HPPDDC)]_n, that contains extended in plane nanoscopic void regions with dimensions of 9.93 × 16.93 Ų. These layers are further integrated into a three-dimensional architecture through interlayer hydrogen bonding, generating nanocage-like cavities of 9.93 × 16.93 × 14.73 ų. Remarkably, each {Y₂} node binds four solvent molecules, an uncommon coordination environment that, upon activation, endows NUC-190a with pronounced Lewis acidic character. At the same time, spatially distributed carboxylate groups and electron-donating pyridyl moieties located on both sides of the lamellar surface impart intrinsic Lewis acid–base bifunctionality. Catalytic studies substantiate this structural design, as a bicomponent system composed of 0.12 mol % NUC-190a and 2.5 mol % n-Bu₄NBr efficiently drives the cycloaddition of epoxides with carbon dioxide to form cyclic carbonates at 100 °C under 1.0 MPa CO₂. NUC-190a also exhibits high efficiency in deacetalization Knoevenagel condensation reactions. Across both catalytic processes, the material demonstrates true heterogeneous behavior, excellent reusability, and wide substrate adaptability. Compared with our previously reported three-dimensional nanoporous MPFs, this work establishes a concise and broadly applicable strategy for constructing two-dimensional frameworks from H₄PPDDC derived, structure oriented ligands, enabling the programmable incorporation of functional groups to access metal organic architectures with tunable properties.

Cimetidine, a popular histamine H2-receptor antagonist, represents a complex structural landscape exhibiting multiple forms. Attempts to synthesize a bicomponent salt with fumaric acid suffered from crystallization challenges in the past, especially toward the growth of anhydrous single crystals. In this work, we address these crystallization challenges by adopting an alternative crystallization approach involving ionic liquids and analyzing the structural landscape with a large synthon-based approach. Two novel forms of cimetidine fumarate were isolated. The structural differences in the forms of cimetidine fumarate were further explored by using different coformers as structural probes.

Polymorphs can be characterized by the use of eutectic melting point data, which permits the determination of both the thermodynamic stability relationships for anhydrous polymorphic systems and the transition temperature for enantiotropic polymorphs. This technique requires the selection of suitable additives to produce eutectic mixtures. However, there is very limited information in the literature about how these additives should be selected. This gap is addressed herein through the study of the reported additives and their physical properties. A set of additives with wide applicability is recommended, and guidance on the selection process is presented.

Two novel viologen-based yttrium metal–organic frameworks, [Y₄(H₂bcbp)(bcbp)(μ₂-C₂O₄)₆(H₂O)₂Cl₂]·4H₂O (1) and [Y₂(bcbp)(μ₂-C₂O₄)₂(NO₃)₂]·H₂O (2), were solvothermally synthesized and characterized. Compound 1 displays a three-dimensional (3D) structure with a dia (sqc-6) topology based on (6,3)-hcb yttrium-oxalate layers. Compound 2 displays a 3D structure with a 2-fold interpenetrating mog topology based on yttrium-oxalate chains. Both compounds possess photochromic behaviors induced by photoinduced electron transfer (PET) generating viologen radicals, as confirmed by UV–vis and EPR spectroscopy. Based on these properties, compound 1 is utilized in inkless and erasable printing. Furthermore, compound 1 can serve as a highly sensitive and selective fluorescence sensor for nitrofuran antibiotics (NFZ and NFT) in aqueous systems, with low detection limits LODs (2.11 × 10^–7 M for NFZ and 1.56 × 10^–7 M for NFT), high quenching coefficients K_SV (5.43 × 10⁴ M^–1 for NFZ and 3.82 × 10⁴ M^–1 for NFT), and excellent selectivity and recyclability. The quenching mechanism is attributed to a synergistic effect of the inner filter effect (IFE), fluorescence resonance energy transfer (FRET), and PET. This work highlights the potential of viologen-based MOFs in smart materials and environmental monitoring.

The benzo[1,2-b:4,5-b′]difuran core has emerged as a building block for the development of electronic and optoelectronic compounds, pharmacologically active molecules, and even antiproliferative tools for different cancer cell lines. In our past research articles, we analyzed the properties of a series of diaminobenzo[1,2-b:4,5-b′]difuran derivatives with different substituents, both from the functional and crystallographic points of view. We herein have investigated the effect of different crystallization conditions on 2,6-diamino-benzo[1,2-b:4,5-b′]difuran-3,7-diethyl ester. We both obtained the known colorless crystalline structure 1a(RT) and another violet colored crystal form containing DMF as guest molecules, named 1b. On the other hand, we recorded the ability of 1a(RT) to change into another colorless crystal form named 1a(LT) at 100 K, undergoing a reversible-phase transformation accompanied by a reversible twinning/detwinning process. The solid-state assembly of the three crystal forms was deeply examined; specific absorption curves and colorimetric coordinates were studied, and the energetic characteristics were derived by computational methods.

A series of NaRESe₂ (RE = Sm, Gd–Lu) compounds were synthesized as single crystals, and NaRESe₂ (RE = Ce, Pr, Nd) was synthesized as polycrystalline powders using the boron chalcogen mixture (BCM) method. The detailed synthesis, single-crystal structure characterization, magnetic properties, and optical properties of the NaRESe₂ series are reported. The structures of the crystals were characterized by single-crystal X-ray diffraction. This series crystallizes in the trigonal (R̅3m) crystal system, where the RE³⁺ ions form a triangular lattice. Magnetic property measurements of NaRESe₂ (RE = Ce - Nd, Sm, Gd - Yb) indicate the presence of possible antiferromagnetic correlations that were observed in all compounds; however, no long-range magnetic order was observed, suggesting the presence of magnetic frustration. The band gap energies of NaRESe₂ (RE = Ce - Nd, Sm, Gd- Lu) were determined by UV–vis diffuse reflectance measurements. NaRESe₂ (RE = Gd, Tb, Lu) were shown to luminesce; photoluminescence quantum yield (PLQY) measurements were performed on polycrystalline samples of NaRESe₂ (RE = Gd, Tb, Lu).

In this study, a series of sodalite/BiOBr composite photocatalysts were successfully synthesized via a liquid-phase self-assembly strategy and applied to the efficient visible-light-driven degradation of Rhodamine B (RhB). Structural characterizations confirmed the successful integration of sodalite (SOD) and BiOBr, with the SOD/BiOBr (3:7) composite exhibiting an optimal morphology, enhanced interfacial contact, and favorable physicochemical properties. The composite demonstrated broadened visible-light absorption, improved photogenerated charge carrier separation, and significantly enhanced photocatalytic activity, achieving a degradation efficiency of 97.82% within 15 min. Moreover, the SOD/BiOBr (3:7) composite exhibited excellent stability and recyclability, retaining 86.31% of its initial photocatalytic performance after four consecutive cycles. These findings highlight the great potential of SOD/BiOBr composites as highly efficient and reusable photocatalysts for the removal of organic pollutants. Furthermore, LC-MS analysis identified several degradation intermediates, and two possible degradation pathways─N-deethylation and cleavage of the conjugated ring structure─were proposed. Radical trapping experiments indicated that hydroxyl radicals (•OH) and photogenerated holes (h⁺) were the dominant reactive species involved in the photocatalytic degradation process.

Rutile-type germanium dioxide (r-GeO₂) is an ultrawide-bandgap semiconductor with ambipolar doping ability. This study examines the mist chemical vapor deposition of GeO₂ on (100)-oriented cubic 3C-SiC, motivated by the small lattice mismatch (0.97%) between (001) r-GeO₂ and (100) 3C-SiC. However, X-ray diffraction and electron backscattered diffraction (EBSD) analyses revealed that the films consisted of amorphous and polycrystalline α-quartz GeO₂, rather than r-GeO₂. Scanning electron microscopy images and EBSD inverse pole figure maps suggest random nucleation of α-quartz GeO₂, and the diffusion length of adatoms varies with the growth temperature. A variation in the slope of the Arrhenius plot for the growth rate was observed at a growth temperature around 650 °C, indicating a change in the growth mode. These results demonstrate that lattice length matching alone is insufficient to stabilize r-GeO₂ and highlight the critical role of the substrate nature in realizing r-GeO₂ thin-film growth.

A 5-amino-2-hydroxybenzoic acid-modified triazine polycarboxylate metal–organic framework [Cd(ODTBBA)] 5DMF·3H₂O (Compound 1) has been successfully designed and synthesized based on the triazine poly(carboxylic acid) ligand ODTBBA (5,5′-((6-oxo-1,6-dihydro-1,3,5-triazine-2,4-diyl)bis(azanediyl))bis(2-hydroxybenzoic acid)) and the transition metal source Cd(NO₃)₂·4H₂O through the solvothermal method. Compound 1 featured a three-dimensional network structure constructed by the interconnection and interpenetration of Cd–O/N polyhedron and the ligand ODTBBA. Due to the instability of the compound in water and ethanol, we propose a new strategy of stabilizing metal organic frameworks using polymer materials; the complex was mixed into polyvinylidene fluoride for the preparation of Cd-MOF film material. The experimental results showed that the Cd-MOF film material with compound 1 has excellent metal framework stability and fluorescence properties. Therefore, we explored its fluorescence sensing properties. The Cd-MOF film material exhibits sensitive fluorescence responses to nitroaromatic compounds (nitro aromatic compounds) as well as heavy metal cations and anions (Cu²⁺, Fe³⁺, and Cr₂O₇^2–) and can achieve visual sensing of the three heavy metal ions through distinct color changes from pale yellow to dark yellow or black.

The versatility of halogen bonds (XBs) has made them an attractive tool for the design and development of photoresponsive materials. In this work, we have synthesized XB complexes of the alkoxy azo benzonitrile derivative with 1,4-diiodotetrafluorobenzene. The formation of these complexes was confirmed by FTIR spectroscopy and powder X-ray diffraction analysis, while their structural details were further elucidated through single crystal X-ray diffraction studies. To gain deeper insights into the nature of the interactions, computational analyses including molecular electrostatic potential mapping, noncovalent interactions index analysis, quantum theory of atoms in molecules, and natural bond orbital analysis were performed. These studies revealed the weak but significant nature of the XBs, providing both qualitative and quantitative descriptions of these intermolecular interactions. The thermal behavior of the complexes was evaluated by thermogravimetric analysis, differential scanning calorimetry, and hot-stage polarized optical microscopy. The results indicated low thermal stability and the absence of liquid crystalline phases. Interestingly, despite these limitations, the complexes exhibited reversible photoresponsive behavior upon irradiation with suitable wavelengths of light, underscoring their potential for use in light-driven molecular switches and smart materials.