CrystEngComm最新文献

This work emphasizes the role of metal complexation for controlling and tuning static/dynamic π-stacked organizations responsible for the programmed light emission of the bichromophoric pyrene-terimine ligand L2 upon photoexcitation. Its binding to the closed-shell trivalent yttrium guest [Y(hfac)₃] (hfac = 1,1,1,5,5,5-hexafluoro-pentane-2,4-dione) provides a diamagnetic heteroleptic [L2Y(hfac)₃] adduct for which the static intramolecular pyrene-pyrene excimer emission operating in the free ligand L2 is transformed into a dynamic intramolecular pyrene-pyrene excimer emission in the resulting complex. The transition from static-to-dynamic intramolecular excimers results in an enhanced sensitivity toward interactions with electron-poor nitrobenzene guests, which is supported by a considerable Stern-Volmer quenching constant measured for [L2Y(hfac)₃]. This demonstrates that the metal-directed organization of the polyaromatic ligand in [L2Y(hfac)₃] can boost the excimeric chemical sensing of target aromatic analytes.

Flexible metal-organic frameworks (MOFs) exhibit stimuli-responsive phase transitions that enable diverse applications. In this article we report the synthesis and characterisation of a flexible MOF, MFM-261a, [H₂N(CH₃)₂]₂[Ni₃(sbpdc)₄(η-H₂O)₂(μ-OH₂)₂]·solv (H₂sbpdc = sulfonyl-4,4'-biphenyldicarboxylic acid), which exhibits a reversible structural phase transition. Single-crystal X-ray diffraction reveals that MFM-261a crystallises in the orthorhombic space group Pnnm. Upon activation via desolvation, MFM-261a undergoes a single-crystal-to-single-crystal (SCSC) transformation to yield MFM-261b, [H₂N(CH₃)₂]₂[Ni₃(sbpdc)₄(η-H₂O)₂(μ-OH₂)₂]. Crystallographic analysis confirms that MFM-261b retains the metal-ligand coordination as the parent framework but shows a different pore geometry. Notably, MFM-261b can be reversibly converted to MFM-261a by exposure to dimethylformamide, demonstrating structural breathing. Impedance spectroscopic measurements reveal a proton conductivity of 3.00 × 10^-5 S cm^-1 for MFM-261a at 50 °C and 3.41 × 10^-6 S cm^-1 for MFM-261b at 70 °C under 99% relative humidity. The calculated activation energies of 0.63 and 0.68 eV support a vehicular transport mechanism with water molecules facilitating proton transfer. This work demonstrates the potential of flexible MOFs for applications requiring tuneable proton conduction properties.

III-nitride nanowire quantum dots (NWQDs) are in high-demand due to their ability to emit single photons at room temperature across the entire UV to visible wavelength range. Although tremendous progress has been made over the past decade, the efficiency of these QDs has not improved significantly. This limitation arises because true lateral confinement was difficult to achieve owing to challenges in reducing the QD diameter to the radial confinement limit. Furthermore, the presence of a giant built-in potential in NWQDs has restricted their fast operation. In this review article, we present the evolution of the III-nitride NWQD field and discuss how these challenges have been addressed to realize high-efficiency single-photon sources. Towards the end of the article, we demonstrate how these NWQDs can be leveraged to build up a photonic qubit-based quantum computer, which will be capable of operating at room temperature.

The present study is focused on a structure-guided investigation of the pyridine-based scaffold, 1-(3,5-diphenylpyridin-2-yl)ethan-1-one. The study is designed to probe how substitution variation influences the molecular conformation, crystal packing, electronic structure, and biological recognition. The rigid 3,5-diphenyl substitution limits rotational flexibility around the pyridine–carbonyl linkage, providing a structurally defined platform in which substituent-dependent effects are systematically evaluated. Four representative derivatives (MK1–MK4), bearing electron-rich 3,4-dimethoxyphenyl, halogenated dichlorophenyl, hetero aromatic thiophen-2-yl, and extended aromatic naphthyl substituents, were selected to assess substituent-dependent structural variation. Single-crystal X-ray diffraction analysis revealed that MK1, MK2, and MK3 crystallize in the monoclinic space group, whereas the naphthalene-substituted derivative MK4 adopts a triclinic crystal system. The torsional analysis indicates that the carbonyl bridge exhibits substituent-dependent conformational variation. The presence of the carbonyl group (CO) facilitated hydrogen-bond interactions, contributing to overall molecular stabilisation, while also influencing intramolecular charge distribution and potential enzyme binding. Computational DFT analyses revealed differences in π-delocalization and donor–acceptor interactions across the series, with MK3 showing the most consistent electronic interaction. Molecular docking against human butyrylcholinesterase (hBChE), benchmarked against the co-crystal ligand 5HF, identifies MK3 as the compound with the highest binding affinity for the enzyme. Subsequent 100 ns molecular dynamics simulations confirmed that MK3 retained dynamic stability, reflected by reduced ligand R_g, SASA, and MOLSA, indicating compact, solvent-shielded binding. Overall, the structural findings provide insight into how substituent-dependent conformational variation may relate to differences in enzyme binding behaviour across the series.

A hydrogen-bonded organic framework (HOF) was obtained via the formation of a cyclic dimer hydrogen-bonded organic macrocycle (HOM) through rational molecular design. The ordered arrangement of HOMs formed permanently porous 1D channels in the HOF. These channels exhibited the selective adsorption of naphthalene.

This is a Commentary on a paper by Lei Wang et al. (CrystEngComm, 2013, 15, 2835). The protonation state of 2-aminopyrimidine in the crystal structure deposited as REXNIT has been re-examined using periodic density functional theory (DFT) calculations. Motivated by recent literature suggestions questioning the assignment of protonation at the exocyclic amino group, several alternative protonation scenarios were systematically explored within the experimental crystal framework, allowing full relaxation of atomic positions and unit cell parameters. The results demonstrate that protonation at the ring nitrogen N1 represents the only robust and energetically preferred configuration, corresponding to a well-defined global minimum. Protonation at N3 leads to an unstable local minimum that is highly sensitive to the initial proton placement, while protonation at oxygen atoms results in spontaneous proton transfer to N1 during geometry optimization, in some cases yielding locally trapped lattice configurations. These findings provide quantitative support for reconsidering the protonation assignment in REXNIT and illustrate the value of periodic theoretical methods for validating crystallographic models involving proton transfer.

The first family of triple-layered nested lanthanide icosahedral nanocages, which feature a unique concentric architecture bearing a {Na₄} parallelogram core, a {Ln₁₂} icosahedral skeleton and a {L₂₀} dodecahedral shell (Ln = Gd, Dy; L = ligand), have been constructed. Magnetocaloric effect and dual magnetic relaxation behaviour are observed in Gd- and Dy-analogs, respectively.

Copper(I) iodide complexes represent a kind of promising scintillator due to their high luminescence efficiency, low toxicity, cost-effectiveness, and high atomic number of iodine, which enhances X-ray absorption. Herein, we report two copper(I) iodide complexes, Cu₅I₇(Ted-Pre)₂ (1) and Cu₅I₇(Ted-EA)₂ (2), constructed from anionic [Cu₅I₇]²⁻ cluster units and cationic organic ligands derived from triethylenediamine (Ted). Structural analysis revealed distinct bridging modes of iodide anions within the [Cu₅I₇]²⁻ cluster units. Complex 1 contained a rare μ₅-bridging iodide that enhanced the structural rigidity for the [Cu₅I₇]²⁻ unit, which should correlate with its superior photoluminescence quantum yield (72.8%) and improved thermal stability compared to complex 2. Under X-ray excitation, 1 achieved a light yield of 19 010 photons per MeV, surpassing that of the commercial scintillator Bi₄Ge₃O₁₂ (BGO, 10 000 photons per MeV), along with a detection limit of 88.5 nGy s⁻¹, well below the typical medical imaging threshold. When incorporated into a flexible polydimethylsiloxane film, 1 achieved a spatial resolution of 8 lp mm⁻¹ in X-ray imaging. These results highlight the potential of structurally tailored copper(I) iodide complexes as efficient and cost-effective scintillators for advanced X-ray imaging applications.

Understanding the mechanical behaviour of organic molecular crystals is essential for their reliable handling, processing, and performance in solid-state applications. Benzoic acid crystals have been reported to be brittle in previous studies. However, in this work, the benzoic acid crystals grown using slow evaporation and sublimation processes exhibited plastic bending upon the application of force on a wider (001) crystallographic face. Single-crystal X-ray diffraction analysis and pairwise interaction energy calculations revealed the presence of a slip plane along the (001) direction, which was formed mainly due to the herringbone packing arrangement of the benzoic acid molecules and a weak edge-to-edge aromatic interaction. A low-energy (001) slip plane with an interlayer separation of approximately 0.896 Å facilitates the plastic deformation of benzoic acid crystals. Nanoindentation analysis of the (001) face yielded elastic modulus (E) and hardness (H) values of 4.26 ± 0.68 GPa and 128.03 ± 38 MPa, respectively, which fall within the range of values reported for plastic organic crystals.

The technique of Hirshfeld surface analysis has been applied to a selection of crystal structures of metallo-supramolecular grids in order to better define the modes of interaction of the grids with both anionic and neutral species, and to assess the possibilities of using grids as selective receptors. The influence of weak interactions on grid symmetry and hence inequivalence of metal sites within the grids has also been considered as a factor influencing possible electronic uses of grid species.