CrystEngComm最新文献

Brownmillerite-type Ca₂Fe₂O₅ is a mixed ionic and electronic conductor with applications as an electrode material for solid oxide fuel cells and solid oxide electrolyser cells. Long-range oxide ion migration in Ca₂Fe₂O₅ has been computationally predicted to be predominantly two-dimensional, restricted to the (ac) crystallographic plane. We have used the floating zone method to grow large high-quality single crystals of Ca₂Fe₂O₅ and determine its conductivity on two differently oriented single crystal samples in order to directly probe the anisotropy of transport properties. Impedance spectroscopy measurements have shown the conductivity in the (ac)-plane to be up to one and a half order of magnitude higher than that parallel to the crystallographic b-axis. This degree of anisotropy of the conductivity is higher than that observed experimentally in most other oxide ion or mixed conductors belonging to the apatite and melilite structural family, highlighting the suitability of brownmillerite-type materials for applications in devices requiring components in oriented crystal or thin-film forms.

To enhance the 3.9 μm emission of Ho:⁵I₅ → ⁵I₆ transition, this work proposes for the first time the use of Ni²⁺ as a sensitizer. Ni²⁺, Ho³⁺, and Ni²⁺/Ho³⁺ co-doped PbF₂ single crystals were grown by the Bridgman method for verification. Spectroscopic characterization confirmed the effective enhancement of Ho³⁺ emission at 3.9 μm by Ni²⁺, with the emission cross-section increasing from 0.3 × 10⁻²⁰ cm² to 0.51 × 10⁻²⁰ cm². Fluorescence lifetime measurements of the lower ⁵I₆ level revealed a Ho³⁺:⁵I₆ → Ni²⁺:³T_2g(F) energy transfer efficiency of up to 79.7%, significantly surpassing previous Nd³⁺/Ho³⁺ co-doped systems. Furthermore, simulation experiments for a 3.9 μm laser based on the Ni²⁺/Ho³⁺ co-doped PbF₂ crystal were conducted. The simulations further demonstrated the sensitization effect of Ni²⁺ on Ho³⁺ 3.9 μm emission, predicting a theoretical output energy value of 2.88 mJ under a 500 mJ pump input. Therefore, the Ni²⁺/Ho³⁺:PbF₂ single crystal is demonstrated to be a promising gain medium for 3.9 μm solid-state lasers.

Aliphatic dicarboxylate linker ligands are relatively understudied in the field of coordination networks (CNs) compared to their aromatic counterparts. Herein, we report the synthesis and characterisation of three nickel(II) CNs comprised of mixed ditopic linkers, a linear ditopic imidazolyl ligand and three aliphatic dicarboxylates: [Ni(glu)(bimbz)], sql-glu-Ni, [Ni(adi)(bimbz)(H₂O)₂], sql-adi-Ni, and [Ni(muc)(bimbz)(H₂O)]·H₂O, dia-muc-Ni (bimbz = 1,4-bis-(1H-imidazol-1-yl)benzene, glu = glutaric acid, adi = adipic acid, muc = trans, trans-muconic acid). Single crystal X-ray diffraction studies reveal that this family of CNs is comprised from nickel-based octahedral 4-connected nodes linked through nickel-carboxylate and nickel-imidazole coordination bonds. The resulting structures can be described as non-interpenetrated square lattice, sql, (sql-glu-Ni and sql-adi-Ni) or 5-fold interpenetrated diamondoid, dia, (dia-muc-Ni) topology networks. A Cambridge Structural Database (CSD) mining study was conducted to evaluate the effect of node composition and structure on topology in 222 archived CNs of general formula [MLL′], [MLL′(H₂O)], [MLL′(H₂O)₂], [M₂L₂L′] (= “pillared paddlewheel”) and (= “double-walled nets”) where L = aliphatic dicarboxylate linker and L′ = linear ditopic N-donor linker. In terms of prevalence, sql, sql, neb, rob and pcu, respectively, were found to be the most common topologies for each of these compositions. These statistics suggest that aliphatic dicarboxylate linkers can have a profound and consistent effect on the resulting topology for certain node compositions. This is especially the case for “pillared paddlewheel” nets, which favour rob topology over the pcu or “DMOF” topology that dominates for rigid linkers.

Molecular magnetic materials showing magnetic and electrical bifunctionality are highly attractive; however, the construction of such materials is relatively difficult. Herein, a cyanide-bridged CoCu₃ cluster, {[Co^III(CN)₆][Cu^II(TMC)]₃}[[Co^III(CN)₆]]·14H₂O, based on the Cu(II) complex of methyl cyclam (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane) and hexacyanidocobaltate(III), has been prepared and characterized in terms of structure, magnetic properties, and proton conduction. The tetranuclear CoCu₃ cluster exhibits a T-shaped structure with three square pyramidal Cu^II (S = 1/2) centers separated by a diamagnetic [Co^III(CN)₆]³⁻ anion (S = 0). The highly hydrogen-bonded water clusters in the 1D pores of the 3D supramolecular network yield proton conductivities of 5.3 × 10⁻³ S cm⁻¹ at 50 °C under 95% RH. A pronounced temperature sensitivity in both conductivity and activation energy, with a value of 0.32 eV, points towards the operation of the Grotthuss mechanism for proton transportation, which is facilitated by a large amount of lattice water molecules. Magnetic studies reveal easy-axis magnetic anisotropy of the Cu²⁺ ions in a distorted square pyramidal geometry. Interestingly, field-induced slow magnetic relaxation occurring via direct and Raman processes was observed for this complex. This compound is the first example of a Cu^II complex combining slow magnetic relaxation and proton conduction, highlighting the design and construction of magnetic-electrical materials through cyanide-bridged assemblies.

Pyrimethamine (PYR), a 2,4-diaminopirymidine-derived antifolate, is used as an antiparasitic agent, especially for the treatment of toxoplasmosis. We designed and prepared the adducts of PYR with benzoic acid derivatives having two hydroxyl groups on the aromatic ring. We report the formation of four new pyrimethamine salts with differently substituted dihydroxybenzoic acids, namely, 2,3-dihydroxybenzoic acid (23DHBA), 2,4-dihydroxybenzoic acid (24DHBA), 2,5-dihydroxybenzoic acid (25DHBA), and 2,6-dihydroxybenzoic acid (26DHBA). The N(1) nitrogen atom in the pyrimidine ring of PYR is protonated in all obtained structures. The typical PYR–PYR association through a pair of N–H⋯N bonds between the N(4)H₂ amino group of one PYR molecule and the N(3) nitrogen atom of the pyrimidine ring of the second PYR molecule is observed. Despite these similarities, the obtained salts exhibited different molecular packing, induced by the differently positioned additional hydroxyl groups attached to the aromatic ring of the specific dihydroxybenzoic acid. All obtained salts were characterized by single-crystal X-ray analyses, powder X-ray diffraction, thermal analyses (TGA and DSC), Hirshfeld analysis, and DFT calculations.

Correction for ‘Physically stable cyclodextrin metal–organic frameworks formed via a drug-assisted amorphous to crystal phase transition’ by Ryoma Tanaka et al., CrystEngComm, 2025, 27, 7121–7127, https://doi.org/10.1039/d5ce00755k.

This study presents a crystallographic investigation of phosphonated calix[4]-, calix[5]- and calix[6]-arenes, with complementary analysis of their brominated calix[6] intermediates. The influence of upper-rim and lower-rim substituents on molecular conformation and self-assembly is examined. A survey of the Cambridge Structural Database (CSD) confirms a limited number of phosphonated calix[6]arene, calix[5]arene and calix[4]arene structures, stressing a gap in the structural characterization. To address this gap, we report new crystal structures of phosphonated calixarenes bearing various lower-rim alkoxy groups, with brominated calix[6] derivatives included for comparison as key synthetic intermediates. The results suggest that decreasing the ring size enhances structural rigidity, thereby imposing greater constraints on hydrogen-bond organization and packing arrangements. Hirshfeld surface analysis was employed to quantitatively assess intermolecular interactions and packing features across the studied structures.

Development of efficient acetylene (C₂H₂) adsorbents is extremely important for industrial gas purification. In this study, a novel indium–organic framework (In–MOF) with flu-topology was constructed for efficient C₂H₂ separation from gas mixtures. Structural characterization revealed a high specific surface area of 749.9 m² g⁻¹ and a uniform pore size of 6.1 Å of the obtained SNNU-400. Stability studies suggested that SNNU-400 exhibited excellent chemical stability over a wide pH range of 2–11 and superior thermal stability up to 400 °C. Gas adsorption studies at 298 K and 1 atm revealed excellent adsorption capacity for C₂H₂ (105.6 cm³ g⁻¹) compared to CO₂ (61.4 cm³ g⁻¹) and C₂H₄ (74.6 cm³ g⁻¹). Benefitting from the relatively strong C–H_C2H2⋯π_PTO, SNNU-400 showed promising separation potential for equimolar C₂H₂/CO₂ and C₂H₂/C₂H₄ mixtures, as evidenced by high selectivity values (7.4 for C₂H₂/CO₂ and 5.1 for C₂H₂/C₂H₄). This study offers a promising solution for practical industrial applications in the field of clean energy and sustainable chemistry.

Four novel Zn(II)/Cd(II) metal–organic frameworks (MOFs 1–4), namely [Zn_1.5(L)(bibp)(H₂O)]_n (1), [Zn_1.5(L)(bimmb)(H₂O)]_n (2), {[Cd_1.5(L)(bibp)_0.5(H₂O)]·2H₂O·C₄H₈O₂}_n (3) and {[Cd_1.5(L)(bimb)]·2.5H₂O}_n (4) (flexible H₃L = 3-(3,5-dicarboxyphenoxy)-6-carboxypyridine, rigid bibp = 4,4′-bis(imidazolyl)biphenyl, semi-flexible bimmb = 1,4-bis(imidazol-1-yl methyl)benzene and flexible bimb = 1,4-bis(imidazol)butane), were synthesized under solvothermal conditions by using a reasonable design method and further characterized by single-crystal X-ray diffraction (SC-XRD), FT-IR spectroscopy, thermogravimetric analysis (TGA) and powder X-ray diffraction (P-XRD). Structural diversity was achieved by employing the three distinct N-donor ligands described above, and the resulting MOFs exhibited unique architectural topologies as follows: 1 and 2 exhibit entangled 1D chain structures that collectively form a 3D framework, while 3 and 4 possess a 3D network in an interspersed manner. Luminescence studies revealed that these MOFs exhibited high sensitivity and selectivity in fluorescence sensing applications, particularly for Cr₂O₇²⁻ anions with detection limits of 3.64, 2.08, 2.75 and 4.36 μM, respectively. Furthermore, the sensing mechanism for Cr₂O₇²⁻ by MOFs 1–4 is attributed to a competitive absorption process.

In this work, we undertook an in-depth study of the combination of two chiral molecules: 1,1′-Bi-2-naphtol (BINOL) and trans-cyclohexane-1,2-diamine (DACH). While exploring various solvents for developing resolution processes, we revealed a multitude of solid phases. Here is analyzed the different crystalline forms obtained in the selected solvents, underscoring the critical importance of the solvent choice for the development of a chiral resolution process.