Crystal Growth & Design最新文献

Fluorescence from o-carborane derivatives is usually weak in solution due to the robust nonradiative decay via the motion of bond rotation, but it is enhanced in the aggregated states, which is also known as aggregation-induced emission. To the best of our knowledge, there is no other way to significantly enhance the fluorescence intensity of o-carborane derivatives in the reported literature. Also, novel strategies and sensing materials for gaseous acid detection are in high demand due to the aspects of high sensitivity, easy operation, and low cost. Herein, we report the effective fluorescence turning-on phenomenon of crystalline o-carborane derivatives upon exposure to acidic gas, which shows that crystalline o-carborane derivatives can function as effective sensors for acidic environments.

It is highly desirable but still remains challenging to tune nanozymes with superior catalytic activity via simple operation. Herein, the oxidase-like activity of Ru nanoparticles supported on porous carbon (Ru/PC) was significantly modulated via a facile partial oxidation process. Due to the small size, uniform dispersion, high electron density on the surface, as well as abundant interfacial heterostructure between Ru and RuO₂, the partially oxidized Ru/PC (P–Ru/PC) showed excellent oxidase-mimicking activity in triggering 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation, with a low K_m of 0.138 mM and a high V_max of 2.82 × 10^–7 M·s^–1. Theoretical calculations reveal that both the absorption and subsequent activation of molecular oxygen are more favorable on the interfacial heterostructure of P–Ru/PC than on the Ru/PC surface. Moreover, the oxidase-like activity of P–Ru/PC was found to be suppressed by melatonin, along with a fading color of oxidized TMB (TMB_ox). As a result, a novel colorimetric system consisting of P–Ru/PC and TMB was established for melatonin detection for the first time, which shows a wide linear range of 10–220 μM and a low detection limit of 0.023 μM. This work not only provides a simple but smart strategy of interface engineering to tune the oxidase-like activity of Ru/PC, but also expands the application of Ru oxidase mimics in pharmaceutical analysis.

This paper reports a new nicotinamide cocrystal using tetradecanoic acid as a coformer by a slow solvent evaporation method in acetone. Its structural, thermal, vibrational, and antibacterial properties were characterized and discussed. Single-crystal X-ray diffraction data indicated that the NA–TA cocrystal crystallized in triclinic symmetry and $P\overline{1}\left(C_i\right)$ space group, with two formulas per unit cell (Z = 2). A detailed analysis of the intermolecular interactions was performed based on Hirshfeld surface and noncovalent interactions. Thermoanalyses revealed that the material is stable up to around 128 °C and exhibits endothermic events characteristic of solid–liquid phase transition and decomposition. Additionally, using group theory and periodic calculations based on density functional theory (DFT), all inter- and intramolecular modes of the NA–TA cocrystal were predicted and assigned. The experimental infrared and Raman spectra were well correlated to the spectra calculated via DFT, allowing a suitable assignment of the observed vibration modes. Furthermore, biological experiments demonstrated that the cocrystal exhibits promising antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. An in silico study of the pharmacokinetic profile involving absorption, distribution, metabolism, and excretion parameters was performed to support the experimental findings.

A novel antibacterial nicotinamide cocrystal with tetradecanoic acid as the coformer was crystallized using the slow evaporation method. The structural, thermal, and vibrational properties were characterized and analyzed. A detailed study of the noncovalent bonds was conducted using computational methods. Additionally, the inter- and intramolecular modes were assigned through periodic calculations based on density functional theory.

The sublimation thermodynamics of the neuroprotective and potential anticancer drug riluzole was studied by the transpiration method, and the obtained data were used in a virtual screening based on cocrystallization Gibbs free energy estimation. The method was successfully validated against 19 reported riluzole crystal forms and correctly predicted the salt formation with dihydroxybenzoic acid isomers. Variation of experimental conditions led to the isolation of the novel polymorphic modification of riluzolium 2,6-dihydroxybenzoate and the new salt cocrystal of riluzole with 2,3-dihydroxybenzoic acid with an unexpected (3:4) stoichiometry. The hydrogen bond topology was found to be identical in polymorphic forms of riluzolium 2,6-dihydroxybenzoate, and the packing difference is caused by the variable mutual orientation of hydrogen-bonded ribbons. The metastable Form 1 was found to undergo an irreversible exothermic phase transition upon heating, indicating a monotropic relationship between the polymorphs. In serial batch crystallization experiments, Form 1 was found to nucleate at a lower supersaturation level with subsequent transformation to Form 2. Thermodynamic functions of salt formation for riluzolium 2,6-dihydroxybenzoate Form 2 from parent compounds have confirmed that the process is enthalpy-driven. At pH > 4.4, the solubility of Form 2 is found to be higher than that of pure riluzole.

Macroscopic thermosalient effect is observed in a multicomponent bimetallic one-dimensional (1D) coordination polymer (U–Cu–BCP) with five different structural components for the first time, which represents a thermosalient crystalline compound with the highest number of structural components reported to date. A combination of different temperature-dependent characterization techniques containing TGA, DSC, VT-PXRD, and VT-SCXRD unveils that the underlying mechanism for the themo-responsiveness is attributed to anisotropic thermal response of crystal lattice, i.e., positive thermal expansion effect along the stacking direction of 2D supramolecular network and negative thermal expansion effect perpendicular to the stacking direction over 280 K.

Four charge transfer cocrystals of anthracene chalcone compounds containing halogen groups were designed and prepared based on the π···π interactions. Four cocrystals were stacked in the identical D···A···D···A···D···A mode, with electron-rich anthracene chalcone compounds as donors (D) and electron-deficient 1,2,4,5-benzenetetracarbonitrile (TCNB) as the acceptor (A). The successful preparation of cocrystals was confirmed by PXRD and FT-IR tests, and the optical properties of the cocrystals were characterized by solid-state UV and fluorescence tests. Compared with the donors, the UV absorption bands of the four cocrystals had widened to the red region. A significant red shift appeared in the fluorescence emission peaks of the four cocrystals, and the emission quantum yield and fluorescence lifetime were significantly improved. Based on the obtained SXRD crystal data, detailed density functional theory (DFT) calculations were employed to analyze the weak intermolecular interactions in four cocrystals, and the π···π interactions were quantitatively analyzed to confirm the charge transfer effect. Under the influence of the charge transfer effect, the narrowing of the band gap for the four cocrystals induced the change in the transition dipole moment of the excited state, thus achieving modulation of the optical property. This study combines theoretical calculations and experiments to systematically reveal the conformational relationship between stacking modes and optical properties, which provides guidance for the development of novel optical materials.

Two isostructural cobalt(II) and zinc(II) 1D-linear coordination polymers of 2-isonicotinoyl-N-tosylhydrazinecarboxamide (H₃itca) composed of assembled anionic and cationic parts in their respective chain were characterized. Their utility as adsorbent was investigated. The anionic portion of the coordination polymers composed of [M(Hitca)₂]^2- was bridged by the cationic part [M(H₂O)₄]²⁺ (M = Co²⁺ and Zn²⁺). The hydrolytically stable zinc coordination polymer was insoluble in water and had a lower molar conductance (23.5 S m² mol^–1) in water, whereas the cobalt coordination polymer was soluble in water and had a molar conductance of 100 S m² mol^–1 that corresponded to an ionic species, showing its dissociation in solution. It was also confirmed by mass spectrometry. The crystals of both coordination polymers belong to P₂/n, with crystallographic similarity index unity. The zinc coordination polymer had the ability to adsorb select cationic dyes methyl-violet and methylene-blue with absorption capacities of 53.00 and 52.25 mg/g, respectively. It selectively adsorbed methylene-blue or methyl-violet from the corresponding mixture of these two dyes in aqueous solution. On the other hand, the cobalt coordination polymer was not suitable for dye adsorption, but useful in the displacement of intercalated ethidium bromide from calf-thymus DNA effectively.

Radiation detection (dosimetry) most commonly uses scintillating materials in a wide array of fields, ranging from energy to medicine. Scintillators must be able to not only fluoresce owing to the presence of a suitable chromophore but also withstand damage from radiation over prolonged periods of time. While it is inevitable that radiation will cause damage to the physical and chemical properties of materials, there is limited understanding of features within solid-state scintillators that afford increased structural integrity upon exposure to gamma (γ) radiation. Even fewer studies have evaluated both physical- and atomistic-level properties of organic solid-state materials. Previous work demonstrated cocrystalline materials afford radiation resistance in comparison to the single component counterparts, as realized by trans-1,2-bis(4-pyridyl)ethylene (4,4'-bpe). To support the rational design of radiation-resistant scintillators, we have examined all symmetric and unsymmetric isomers of trans-1-(n-pyridyl)2-(m-pyridyl)ethylene (n,m'-bpe, where n and/or m = 2, 3, or 4) solid-state crystalline materials. Experimental methods employed include single-crystal, powder, and electron diffraction as well as solid-state fluorimetry. Periodic density functional theory (DFT) calculations were used to understand the atomistic-level differences in bond lengths, bond orders, and packing. Electron diffraction was also utilized to determine the structure of a nanocrystalline sample. The results provide insights into possible trends involving factors such as molecular symmetry which provides radiation resistance as well as information for rationally designing single and multicomponent scintillators with the intent of minimizing changes upon γ-radiation exposure.

In this work, we present a theoretical investigation of the SrTiO₃ perovskite-supported Pd catalyst in the methanol electro-oxidation reaction. In order to determine the metal-support interactions, we designed a system consisting of a Pd (100) double layer supported on one of the two possible terminations of the (100) perovskite surface. These terminations are characterized by different reducibilities of the layers directly interacting with the Pd bilayer and result in the difference in the stability of the surface-bound intermediates. Despite the fact that the Pd surface is identical in terms of geometry, we observed significant differences in the overpotential required for the reaction; in the case of TiO₂ termination, the overpotential has been determined to be 0.68 V, while in the case of SrO termination, it amounts to as much as 1.35 V. We further investigate the charge transfers within the components of the system and the geometries of the intermediates to unravel the role of the electron structure on the overall efficiency of the process.

The initial use of 2-(pyridin-2-yl)propane-1,3-diol (pypdH₂) in Mn cluster chemistry has afforded two new mixed-valence polynuclear Mn clusters, namely, [Mn₈Ο₅(pypd)(hmp)₃(O₂CCMe₃)₈] (1) and [Mn₁₆Ο₁₀(N₃)₂(pypd)₂{(py)₂CO₂}₄(O₂CEt)₁₂] (2) (hmp^- = deprotonated 2-hydroxymethylpyridine; (py)₂CO₂ ^2- = deprotonated gem-diol form of di-2-pyridyl ketone). Compound 1 features a novel [Mn^III ₇Mn^II(μ₄-O)₂(μ₃-O)₃(μ-OR)₅]⁸⁺ structural core resembling a supertetrahedron T3, lacking two apexes, while complex 2 has a [Mn^III ₁₄Mn^II ₂(μ₄-O)₄(μ₃-O)₆(μ-N₃)₂(μ₃-OR)₂(μ-OR)₈]¹⁴⁺ core consisting of two [Mn₈] subunits related to 1 and thus is a dimeric analogue of 1. Direct current (dc) magnetic susceptibility studies revealed the presence of dominant antiferromagentic exchange interactions between the Mn ions in complexes 1 and 2 and small ground state spin values for both compounds. Overall, this work highlights the capability of polyol-like chelates like pypdH₂ to stabilize high nuclearity 3d metal clusters based on polynuclear building blocks.