CrystEngComm最新文献

The design and synthesis of three-dimensional (3D) covalent organic frameworks (COFs) with exceptional stability and high proton conductivity are critical for advancing high-temperature fuel cells but remain significantly challenging. In this study, thiadiazole groups were successfully incorporated into a novel 3D COF featuring a five-fold interpenetrated diamond network through a bottom-up self-assembly strategy. The proton conduction of the thiadiazole-based 3D COF (NUST-28) under anhydrous conditions reached up to 8.40 × 10⁻² S cm⁻¹ at 120 °C after phosphoric acid doping. Furthermore, the NUST-28 conductor demonstrated good stability at constant temperature and in cyclic experiments. This work paves the way for the design and construction of 3D COFs as platforms for fast ion transportation using reticular chemistry.

In order to overcome the often large activation barriers in heterogeneous catalytic reactions, photocatalysis is a promising path to activate specific molecules with light at moderate temperatures. In particular, bimetallic nanoparticles combining the plasmonic properties of one metal with the high catalytic activity of another are promising antenna–reactor systems. As the nanocrystal surface structure is a major factor in steering surface electronic properties and accompanying activity and selectivity, it is of interest to control the metal nanoparticle growth and composition. The subject of this work is the synthesis of gold–platinum nanoparticles with varying architectures by controlling the growth mechanism. The selection of the reducing agent allows the regulation of the reduction rate of the platinum metal salt, which in turn affects the final morphology of the resulting bimetallic nanoparticles. This allows the synthesis of either core–shell nanocrystals with decorated nanocube corners or dendritic particles under otherwise identical reaction conditions. A dendritic structure requires the rapid deposition of platinum monomers on the surface of the gold particles. This process hinders the diffusion of platinum monomers to energetically preferred sites on the particle surface, which is possible during the formation of core–shell nanocrystals.

We present an intriguing instance of a supramolecular-organic framework (SOF) self-assembling from a chiral naturally occurring lanostane compound extracted from the Thai plant Miliusa sessilis. Intermolecular hydrogen bonding and van der Waals forces among molecules form a kinetically stable 3D supramolecular architecture with 1D hollow chiral nanotubes, while Hirshfeld surface analysis provides a visual assessment of these interactions.

Through surface leaching and ion exchange, nest-like Cu–Co₃O₄ and Cu–ZnO–Co₃O₄ composites were obtained from solid ZIF-67 and hollow ZIF-8–ZIF-67, respectively. Their characterizations suggested that the ratio of oxygen vacancies/lattice oxygen in Cu–ZnO–Co₃O₄ was much higher (1.61) than that of Cu–Co₃O₄ (0.47). The Cu–ZnO–Co₃O₄ composite exhibited an ultra-high persulfate (PDS) activation ability and could degrade the target organic contaminant molecule bisphenol A (BPA) in six minutes under the reaction conditions of 20 mg L⁻¹ BPA, 0.1 g L⁻¹ PDS and 0.1 g L⁻¹ Cu–ZnO–Co₃O₄, demonstrating a degradation rate constant (k) of 0.84 min⁻¹, which was over 28-fold higher than that of the reference, Cu–Co₃O₄ (0.03 min⁻¹). Notably, the robust reusability of the sample was also established based on three successive runs. The mechanistic study suggested that the influence of the active species derived from PDS followed the below order: ¹O₂ > HO˙ > O₂˙⁻ > SO₄˙⁻. The robust catalytic activity of Cu–ZnO–Co₃O₄ could be ascribed to the rich oxygen vacancies, small size of active particles and the porous structure.

Ultraviolet (UV) birefringent crystals have important applications in polarizers, optical isolators and optical information processing. Crystals with large birefringence can enhance the modulation ability of light and realize the miniaturization of devices. However, the birefringence of cyanurates is often limited by the large dihedral angles between anionic groups. In this work, a chiral-driven approach is proposed for the first time to construct cyanurates with large birefringence. We combined racemic or chiral α-methylbenzylamine (α-MBA) molecules with a π-conjugated cyanurate group (CY), which led to the isolation of three organic hybrid cyanurates with wide band gaps >5.10 eV, namely, rac-α-MBACY, R-α-MBACY, and S-α-MBACY. Notably, the presence of chirality leads to a significant reduction of the dihedral angle between the α-MBA cation and (H₂C₃N₃O₃)⁻ anion and a threefold increase in birefringence from 0.113@546 nm to 0.344@546 nm and 0.338@546 nm. The birefringence values of R-α-MBACY and S-α-MBACY exceed those of most of the cyanurates and commercial crystals, indicating their potential as UV birefringent crystals. This work provides new insights into the design and syntheses of UV birefringent materials.

By adjusting the pH values, two types of heterometallic complexes originated from the same raw materials but with different structures and colors have been successfully designed and constructed. Eleven 3d–4f cobalt–lanthanoid heterometallic complexes, [Ln₂Co₂(2,5-DCB)₁₀(phen)₂] [Ln = Nd (1 and 1a), Sm (2 and 2a), Eu (3 and 3a), Gd (4), Tb (5), Dy (6), Er (7), and Yb (8)], were prepared through the self-assembly reactions of Ln(NO₃)₃·nH₂O, Co(NO₃)₂·6H₂O, 2,5-dichlorobenzoic acid (2,5-HDCB), NaOH, and 1,10-phenanthroline (phen) under solvothermal conditions. All of these complexes were characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Complexes 1 and 1a (2 and 2a, 3 and 3a) are available at different pH ranges, respectively. Their structures and colors are different from each other. Complexes 1–8 and 1a–3a are found to be isostructural, respectively. The photoluminescence properties of 3 and 3a as well as the magnetic properties of 1, 2, 1a, 2a, and 4–8 were investigated. Complexes 3 and 3a display similar characteristic luminescence of Eu(III) and different emission lifetimes. Complex 4 exhibits weak ferromagnetic coupling between the spin carriers below 10 K, and complex 6 shows a slow magnetic relaxation behavior.

Crystallization of N-chlorosaccharin with quinuclidine (QN) produced QN-Cl⁺ cations showing a covalent bond between chlorine and a tertiary nitrogen atom. Strong (supramolecular) halogen bonds between the QN-Cl⁺ and Cl⁻ anions in their 2 : 1 and 1 : 1 complexes comprise a large contribution of orbital (covalent) interactions.

In this contribution, a series of copper(II) discrete and polymeric coordination compounds, namely [Cu₃L₂(aze)₂]_n·nH₂O (1·nH₂O), [CuL₂]·H₂O (2·H₂O) and [CuL(H₂O)(Haze)]·H₂O (3·H₂O) were fabricated from (pyridin-2-yl)methylenenicotinohydrazide (HL) and azelaic acid (H₂aze), using evaporative crystallization, grinding and slurry synthesis methods. The solvent crystallization method produced a crystalline precipitate of complex 1·nH₂O. The filtrate allowed the production of crystals of complex 3·H₂O. The grinding synthetic method gave rise to a mixture of complexes 1·nH₂O, 2·H₂O and an undetermined phase. Results of the slurry synthetic approach highly depend on the stirring time. The obtained coordination compounds have been fully characterized by single crystal X-ray diffraction revealing different structures of complexes, viz. from mononuclear homo- and heteroleptic complexes (2 and 3) to a 1D heteroleptic coordination polymer (1). DFT calculations on non-polymeric complexes were conducted to evaluate the hydrogen-bonding and π-stacking interactions that play a critical role in the solid-state structures of complexes 2 and 3. Additionally, the impact of co-crystallized water molecules, which enhance the π-stacking interactions, was analyzed using energy decomposition analysis.

A series of 4-aminopyridinium (4ap) hypodiphosphates has been synthesized and characterized by variable temperature (VT) optical microscopy, thermogravimetry (TGA-DSC) and X-ray diffraction techniques (SC-XRD, PXRD, VT μ-PXRD). Anhydrous salts (4apH)(H₃P₂O₆) (2) and (4apH)₂(H₂P₂O₆) in monoclinic (C2/c) (4), orthorhombic (P2₁2₁2₁) (5) and another monoclinic (Cc) (6) polymorphic modifications were obtained by single crystal-to-powder dehydrations of the hydrates: ionic co-crystal (4apH)₂(H₂P₂O₆)·H₄P₂O₆·2H₂O (1) and salt (4apH)₂(H₂P₂O₆)·2H₂O (3), respectively. Compound (2) was the only anhydrous form which was also obtained by a typical solution-crystallization. Destructive dehydrations strongly affected hypodiphosphate substructures, generating new structural motifs (both in PP–PP and ap–PP interactions) and new crystal architectures, thus revealing the structural diversity in organic hypodiphosphates. Dehydration gave rise to new properties, as non-centrosymmetric and polar anhydrous structures, (5) and (6) respectively, were obtained from centrosymmetric hydrate (3).

Two one-dimensional coordination polymers, PhHg(3-alkoxycyclobutene-1,2-dione-4-thiolate) (alkoxy = OMe and OEt), have been synthesised, characterised spectroscopically, crystallographically and through computational chemistry techniques. Both species exhibit intermolecular Hg⋯O σ-hole spodium bonding as well as intramolecular Hg⋯O π-hole spodium bonding. In the ethoxy species there are complementary σ-hole O⋯S chalcogen bonds to the Hg⋯O σ-hole spodium bonding as well as orthogonal Hg⋯S π-hole spodium bonding. Each of the coordination polymers is connected into a supramolecular layer. For the methoxy derivative, the layer features π(cyclobutene)⋯π(phenyl) stacking and side-on CO⋯π(cyclobutene)/anti-parallel carbonyl⋯carbonyl interactions. For the ethoxy species, Hg⋯S, offset π(cyclobutene)⋯π(cyclobutene) stacking and CO⋯π(cyclobutene) interactions occur within the layer. In each case, weak C–H⋯π interactions operate between the two-dimensional arrays. The nature of the electron transfer responsible for the spodium/chalcogen bonding has been established. In terms of QTAIM energies, those associated with Hg⋯O σ-hole spodium bonds were in the range of 17.5 to 23.3 kJ mol⁻¹, which were less than the energies computed for the intramolecular Hg⋯O π-hole spodium bonds in each case (31.0 to 43.6 kJ mol⁻¹). The lowest energies for the intermolecular Hg⋯O spodium bonding were computed for the ethoxy species, which correlates with the compensating Hg⋯S π-hole spodium bonding (2 × 11.0 kJ mol⁻¹) and O⋯S chalcogen bonding (12.5 kJ mol⁻¹). The electron transfer leading to the Hg⋯O/S spodium bonding involves donation of an oxygen- or sulphur-bound lone pair of electrons to the σ*(Hg–C) orbital, with the intramolecular Hg⋯O spodium bond involving two lone pair interactions. The O⋯S chalcogen bond is assigned to LP(O) → σ*(C–S).