CrystEngComm最新文献

Hydrogen-bonded dimerization of a C₃-symmetric tribenzotriquinacene-based molecular bowl (C₃-1) orchestrates the formation of supramolecular assemblies characterized with exceptional guest-induced structural modulation. In the absence of guest molecules, C₃-1 assembles into π⋯π stacking dimers devoid of a predefined cavity, yet it exhibits remarkable structural plasticity upon guest binding. The introduction of small aromatic and aliphatic guests—including cyclohexane, benzene, and o-/m-/p-xylene—triggers dynamic, self-adaptive structural transformations, culminating in the formation of host–guest complexes with distinct architectures. X-ray crystallography reveals pronounced structural variations among these assemblies, underscoring the pivotal role of hydrogen bonding and host–guest interactions in directing supramolecular organization. This study illuminates a versatile design paradigm for tribenzotriquinacene-based molecular cages with tunable properties, offering promising candidates for applications in molecular recognition, selective encapsulation, and crystal sponge technologies.

Uric acid (UA) is a vital indicator of various metabolic diseases, and tryptophan (Trp) is one of the eight essential amino acids in the human body. UA and Trp play important roles in maintaining human health. Herein, a fluorescent Zn(II) metal–organic framework (MOF), {[Zn₂(bptc)(1,2-mbix)₂]₂·EtOH}_n (1) (H₄bptc = 3,3′,4,4′-biphenyltetracarboxylic acid, 1,2-mbix = 1,2-bis(2-methyl-imidazol-1-ylmethyl)benzene), was obtained and explored for sensing UA and Trp. MOF 1 is a 3D framework with an interesting two-fold interpenetrated bbf topology. It exhibits excellent fluorescence performance for turn-off sensing of UA and turn-on sensing of Trp in water. The limits of detection (LODs) for UA and Trp are 1.26 and 0.30 μM, respectively. Experimental results and theoretical calculations indicate that the turn-off sensing of UA should be attributed to the competitive absorption between 1 and UA and that the turn-on sensing of Trp should be attributed to the photoinduced electron transfer (PET) from Trp to the ligands of 1. Moreover, the practicality of 1 was verified by detecting UA in serum and Trp in milk.

The Czochralski (CZ) method is widely used for growing high-purity germanium (Ge) crystals, essential for infrared optics, radiation detectors, and high-mobility transistors. However, thermal stress accumulation, dislocation formation, and unstable growth interfaces remain significant challenges in germanium crystal fabrication. This study presents a numerical investigation of the impact of crucible movement on temperature distribution, melt convection, stress accumulation, and defect formation in CZ germanium growth. Results show that a moving crucible improves temperature uniformity, reducing radial thermal gradients that contribute to stress-induced defects. Melt convection patterns are stabilized, preventing undercooling at the crucible bottom and ensuring more uniform heat distribution. The crystal–melt interface remains smoother, reducing the formation of slip bands and stacking faults—defects that degrade electrical and optical performance in germanium devices. Furthermore, von Mises stress analysis confirms that crucible movement significantly lowers stress accumulation, decreasing dislocation density in the grown crystal. These findings align with experimental studies on germanium CZ growth and provide practical process optimizations for improving semiconductor-grade germanium crystal quality. The results have direct applications in infrared imaging, space solar cells, and high-speed electronic devices, where defect-free germanium is essential.

Single crystals of prism[5]arene and prism[6]arene were grown from solutions containing either 1,6-dibromohexane or 1,8-dibromooctane. The deeper cavity of the prism[5]arene macrocycle efficiently encapsulated longer alkyl dibromide guests compared to pillar[5]arene, forming 1 : 1 inclusion complexes stabilized by multiple C–H⋯π and C–H⋯O interactions. Both inclusion complexes self-assembled into linear supramolecular polymers within the crystal network, facilitated by guest halogen interactions (C–H⋯Br and Br⋯Br interactions). Prism[6]arene co-crystals grown from 1,6-dibromohexane and 1,6-dibromooctane formed a unique 1 : 1 inclusion complex, where the guest adopted an orthogonal orientation within the host cavity. The resulting supramolecular assemblies were fully characterized using single-crystal X-ray diffraction and Hirshfeld surface analysis.

The present investigation focussed on assessing the ability of (4R,5R)-bis(diphenylhydroxymethyl)-2-spiro-1′-cyclohexane-1,3-dioxolane (TADDOL6) to separate pyridine/methylpyridine (picoline) mixtures through supramolecular chemistry protocols. At the outset, TADDOL6 was revealed to possess the ability to form 1 : 1 host : guest inclusion compounds with each of pyridine (PYR) and 2-, 3- and 4-methylpyridine (2MP, 3MP and 4MP) in single solvent crystallization experiments. This host compound, furthermore, demonstrated enhanced selectivities in PYR/MP mixtures: preferred guests were PYR and 3MP (in the absence of PYR), followed by 4MP and then 2MP. Subsequent binary guest competition experiments showed that TADDOL6 may be employed in order to effectively separate very many of these mixtures in this way, and significant selectivity coefficients (K) were calculated in numerous instances. Single crystal X-ray diffraction (SCXRD) experiments showed that the only significant (host)π⋯π(guest) stacking interactions were those between TADDOL6 and the preferred PYR and 3MP guest molecules, while a consideration of Hirshfeld surfaces demonstrated that these preferred guests were involved in a tighter packing motif with TADDOL6 than those with 2MP and 4MP. Results from thermal analyses, more specifically when determining the guest release onset temperatures (T_on) and the enthalpies associated with these release processes, also agreed with the host selectivity order in the mixed guest competition experiments.

In this work, four novel halogen-bonded cocrystals of three racetam-family pharmaceutical compounds, named etiracetam, aniracetam and nefiracetam, were prepared using perfluorinated iodobenzenes as halogen bond donors through both mechanochemical and solution crystallization methods. The cocrystals were characterized by powder X-ray diffraction and single crystal X-ray diffraction. Structural analysis revealed that in all of the obtained cocrystals, the most prominent supramolecular interaction is the I⋯O_carbonyl halogen bond. In all cocrystals, the donors are ditopic, while additionally forming an I⋯π halogen bond in the cocrystal of (NEFI)(DITF). In order to rank the acceptor sites, molecular electrostatic potentials of racetam pharmaceutical compounds were calculated on their optimized geometries. Furthermore, Hirshfeld surface analysis was performed to explore the intermolecular interactions in detail. These calculations were consistent with experimental observations, providing a comprehensive understanding of the cocrystal structures and intermolecular forces.

Nitrogen doped n-type SiC substrates are extensively employed for high-power devices thanks to their excellent physical properties. However, the growth of SiC single crystals via the physical vapor transport method still faces large challenges including the control of temperature fields, regulation of the C/Si ratio at the growth front, and intra- and inter-substrate resistivity uniformity improvement. Numerical simulations have been performed to study the evolution of temperature, C/Si ratio and nitrogen incorporation at the growth front as a function of crystal length. Gas exchange across the crucible and crucible etching reaction were considered, and the effects on the crystal growth rate, temperature, C/Si ratio and N₂ distribution at the growth front were illustrated. The computational results show unprecedented agreement with experimental observations. The factors influencing crystal resistivity have been demonstrated. The nitrogen doping efficiency in 4H-SiC crystal growth through the PVT method has been proposed through computed and measured nitrogen concentrations.

Cannabidiol (CBD) is a non-psychoactive compound derived from cannabis and has attracted considerable attention due to its potential therapeutic benefits. It is increasingly used in various health-related products, including dietary supplements, because of its positive effects on pain relief, antioxidative properties, and protection against cell damage. Despite its promising applications, CBD faces significant challenges for oral administration, primarily due to its low solubility, low melting point (67 °C), and poor stability. In this work, we used various methods for CBD cocrystal preparation to improve properties of CBD. We succeeded in preparing five cocrystals, which were fully characterized using several analytical tools, such as X-ray powder diffraction, differential scanning calorimetry, and nuclear magnetic resonance. Notably, the cocrystals increased their melting points compared to pure CBD. Furthermore, the intrinsic dissolution rate was measured for pure CBD and the multicomponent forms to describe the rate of release of CBD from the cocrystal. Finally, the crystal structures of three cocrystals were used to interpret the stability and degradation behaviour of the CBD cocrystals under accelerated conditions. Remarkably, the cocrystals CBD–4,4′-bipyridine and CBD–L-proline remained stable and unaffected for a longer period under stress conditions compared to the pure CBD. This study provides valuable insight into the stability behaviour of the cocrystals under various conditions.

Mineral nanoparticles (NPs) play a crucial role in biological systems, exhibiting enzyme-like “nanozyme” activity in protein oxidation and hydrolysis. To study NP interactions at the molecular level, we characterized complexes of peptides with poly-oxo-metalate (POM) species, the smallest known NPs. Our findings highlight the importance of factors such as metal–oxygen bond polarity, peptide hydrophilicity, medium conditions, and structure-directing amino acids. Using single-crystal models and 2D NMR, we also explored interactions between larger NPs as nanozymes and proteins relevant for specific oxidation of amino acids and proteins.