Crystal Growth & Design最新文献

In contrast to spectroscopy-based technologies such as NMR, mass spectrometry, and computational prediction of spectroscopic properties, single-crystal X-ray diffraction analysis emerges as the most dependable method for structural determination. It serves as the definitive method, particularly in challenging cases, where other approaches fail to yield precise results. However, the generation of high-quality single crystals remains a frequently encountered obstacle. Here, we present a strategy employing an alignment medium to enhance the growth of single crystals for small organic compounds. Furthermore, a mathematical crystallization model based on classical nucleation theory was conducted specifically designed for alignment media. The hypothesis suggests that alignment media effectively reduce the solution entropy, thereby lowering the free energy barrier associated with crystal nucleus formation and facilitating the crystallization process. Employing an alignment medium derived from self-assembled oligopeptide nanotubes (AAKLVFF), we successfully cultivated single crystals of diverse organic compounds. Our discovery unveils an innovative concept and an accessible approach for acquiring single crystals of organic compounds.

A total of 28 halogen-substituted (-F/-Cl/-Br/-I/-CF₃) phenyl benzoates were synthesized from the corresponding -F/-Cl/-Br/-I substituted phenol and the corresponding unsubstituted, fluoro- and trifluoromethyl-substituted benzoyl chloride. These compounds were characterized via ¹H NMR, single-crystal X-ray diffraction, and differential scanning calorimetry (DSC) to evaluate the role of structural similarity at the supramolecular level (isostructurality) associated with the solid state. In the crystal structures, along with the presence of traditional one-dimensional C–H···O hydrogen bonds, O(lp)···π, π···π, and halogen bonds contributed toward the arrangements of isomorphous solids. XPac analysis revealed that out of twenty-nine crystal structures, twenty-two exhibit structural similarity (four pairs of 3D, four pairs of 3D/2D, four pairs of 2D, one pair of 2D/1D), and twenty-seven pairs of 1D-isostructural relationship through the formation of chains and stacking interactions. Also, crystal structures with Z′ > 1 were analyzed in terms of their isostructural behavior. In this regard, 3-chlorophenyl 4-(trifluoromethyl)benzoate exhibited the formation of concomitant polymorphs. This is due to the presence of multiple molecules in the asymmetric unit, wherein more than one supramolecular construct was observed in the solid state. The positive MESP observed in halogens (-Cl/-Br/-I) supports the involvement of the σ-hole in halogen bonding, which in turn governs isostructurality. The lattice energy of the isostructural solids, as well as the nonisostructural solids (isomers), was computed, and it was observed that all the isostructural pairs of molecules have similar lattice energies.

The single-crystal structures of two in situ high-pressure crystallized analogous fluoroiodoalkanes, 1,1,1,2,2-pentafluoro-2-iodoethane (C₂F₅I) and 1,1,1,2,2,3,3-heptafluoro-3-iodopropane (C₃F₇I), were determined at room temperature and selected high-pressure points between 0.75 and 2.60 GPa. The molecules of C₂F₅I show disorder in the whole investigated pressure range, from 1.23 to 2.60 GPa, whereas those of C₃F₇I are ordered between 0.75 and 1.27 GPa. Despite the similarities in the arrangement of atoms within molecules, reflected in the same staggered conformation, these two halogenated alkanes show different interaction and packing features. Besides the F···F forces, only the molecules of C₂F₅I are joined together by the I···F contacts, some of which represent the very short interactions of this type for homomolecular crystals. The I···I contacts are exclusively found in C₃F₇I, but they first formed at a pressure of ca. 0.8 GPa.

Numerous perovskite defects and inferior buried interfaces considerably limit the stability and efficiency of inorganic cesium halide perovskite solar cells. Here, an organic additive, N-(2-acetamido)-2-aminoethanesulfonic acid (AAESA), is added into a CsPbIBr₂ precursor for simultaneously ameliorating CsPbIBr₂ perovskite quality through manipulating perovskite crystallization and healing the buried interface through forming an AAESA interlayer at the interface. It is found that the interaction of the AAESA molecule with the CsPbIBr₂ precursor component slows the perovskite crystallization rate, which results in the fabrication of CsPbIBr₂ perovskite film with improved crystal quality and enlarged crystal grains. Meanwhile, AAESA molecules are pushed downward during the perovskite crystallization process and form an interlayer at the buried CsPbIBr₂ perovskite/TiO₂ layer interface, which heals the buried interface and accelerates the interface charge transfer. The resulting planar CsPbIBr₂ perovskite solar cell with a carbon electrode demonstrates an efficiency of 10.89%. Moreover, the cell without encapsulation preserves ∼90% of the original efficiency after 960 h under ambient conditions, indicating a high stability.

Brady’s test has been utilized to detect the presence of aldehyde and ketone functional groups in organic chemistry laboratory experiments. In this study, we have discovered that crystalline Brady’s reagent (2,4-dinitrophenyl hydrazine, DNPH) is photothermally active, and its single crystals are elastically flexible. A series of hydrazones were synthesized by condensation of DNPH with benzaldehyde and its chloro-substituted ones. Single crystals of most of these hydrazones showed elastic flexibility and UV-induced photothermal effect. The rise in temperature due to the photothermal effect induces bending and vibrational behavior in the single-crystal cantilever beams. The photothermally driven actuation and elastic nature of these crystals refer to the versatility of the organic crystals for use in advanced photoinduced and mechanically flexible actuators.

Chemical oxidation of chrysene with GaCl₃ affords a trimeric chrysene radical dication, [(C₁₈H₁₂)₃]²⁺, crystallized with two Ga₂Cl₇^– anions, as revealed by single crystal X-ray diffraction analysis. In the crystal structure, 1D π-stacked columns of chrysene with interplanar contacts averaged at 3.303(3) Å are separated by Ga₂Cl₇^– anions. Computational studies reveal that the positive charge is concentrated largely on the terminal chrysene units with charges of +0.84 and +0.80, while the center chrysene has a comparatively lower charge of +0.36. This charge distribution is corroborated with structural features of the trimer, as the terminal chrysene molecules exhibit a more pronounced core deformation. Taking the neutral trimer as a reference, much weaker interactions are observed in the title chrysene trimer bearing a +2 charge, suggesting the presence of substantial electrostatic repulsion.

A radical dication trimer of chrysene was successfully synthesized through chemical oxidation with GaCl₃ and crystallographically characterized as [(C₁₈H₁₂)₃]²⁺[(Ga₂Cl₇)⁻]₂. Charge distribution within the trimeric unit was further evaluated through structural and theoretical analysis.

Organic compounds that possess more than four polymorphs are rare. Herein, we report that the compound, PTZ-hexyl-NMI, with a phenothiazine (PTZ) electron donor and a 1,8-naphthalimide (NMI) electron acceptor bonded to opposite ends (α, ω-) of a flexible hexyl chain via the respective heterocyclic N atoms crystallizes from organic solvents in seven different polymorphs depending on solvent, concentration, crystallization temperature, and cooling rates of the solutions. Static low temperature crystallizations (<4 °C) from a variety of solvents give an orange monoclinic (P2₁/c) form, whereas higher temperature crystallizations give an orange orthorhombic form (Pbca). The Pbca form undergoes an irreversible phase transition at 260 K to the monoclinic (P2₁/c) form that is accompanied by an anti-/gauche-conformational change of hexyl atoms, thus providing a new example of conformational polymorphism. Dynamic cooling of ethanol solutions produces other crystal forms, although only a yellow orthorhombic (P2₁2₁2₁) form could be reproducibly prepared in bulk. The different solid forms of PTZ-hexyl-NMI vary in color along the spectrum from yellow to orange, including instances of yellow/orange dichroism. The orange and dichroic forms exhibit close donor–acceptor aromatic stacking interactions, whereas the yellow forms are more loosely packed. In addition to the conformational flexibility of the hexyl chain, the polymorphic behavior arises due to a variety of comparable-strength noncovalent interactions. Namely, comparable CH···O weak hydrogen bonding interactions that possess either PTZ, naphthalimide, or hexyl hydrogen donors give rise to different intermolecular (polymeric) connectivities. Similarly, different types (donor–donor, acceptor–acceptor, and donor–acceptor) and geometries of pi-stacking interactions (exacerbated by the butterfly-shaped phenothiazine donor that differentiates the top from bottom sides of the molecule) contribute to the polymorphism of the compound.

The discovery and development of new scintillation materials support national security needs. In these applications, large volumes of scintillator crystals are needed to achieve efficient screening for contraband. Therefore, one important step in the discovery of new scintillator compositions is testing their feasibility for scale-up and their stability. In this work, high-quality Ø22 mm crystals of two new scintillators RbSr₂Br₅:Eu and RbSr₂I₅:Eu were grown via the Vertical Bridgman method, and their scintillation properties were characterized. The Ø22 mm RbSr₂I₅:Eu crystals could be grown with fast translation rates up to 3.5 mm/h. Both RbSr₂Br₅:Eu and RbSr₂I₅:Eu had high scintillation performance, including light yields of 46,000 and 61,000 ph/MeV,respectively, for Ø22 × 35 mm crystals. Additionally, properties related to physical stability were investigated, including the coefficients of thermal expansion via high-temperature X-ray diffraction (HTXRD) as well as moisture sensitivity. HTXRD confirmed the absence of solid–solid phase transitions and showed that RbSr₂Br₅ had minimal thermal expansion anisotropy compared to RbSr₂I₅ and some other inorganic metal halide scintillators, which favors the growth of large-sized crystals.

Size distributions of different nanostructures, including length distributions of highly anisotropic semiconductor nanowires and nanomembranes, determine statistical properties within large ensembles of such structures. This is paramount from a fundamental viewpoint and for device applications. We study the Becker–Döring equations for heterogeneous growth with size-linear forward and backward rate constants that describe surface diffusion fluxes from the bottom to the top of the structures and in the reverse direction. Additionally, we account for a nucleation delay in the very first monolayer on a substrate. The strength of backward diffusion determines two principally different growth regimes: either limited growth with a length saturation or infinite growth, where the average length increases exponentially with time. We obtain three-parametric analytical solutions for the size distribution in both regimes, given by a modified Polya distribution for limited growth or a modified β-distribution for infinite growth. We analyze the size distribution shapes versus the control parameters and their scaling properties in the continuum limit and fit the length distributions of different III–V nanowires. These results should be useful for understanding and controlling the size distributions of different nanostructures and shed more light on the statistical properties at the nanoscale.

Four distinct functionalized, isostructural, and highly luminescent europium-based metal–organic frameworks (MOFs), namely, Eu-BDC-PC (BDC: benzene dicarboxylic acid; PC: 2-pyridine carboxaldehyde), Eu-BDC-MA (maleic anhydride), Eu-BDC-SA (sulfamic acid), and Eu-BDC-DPC (diphenyl phosphoryl chloride), were synthesized through postsynthetic modification methodology using Eu-BDC-NH₂. The ability of these functionalized Eu-MOFs for the sorption of U(VI) from aqueous solutions was investigated in batch mode. U(VI) sorption studies confirmed that these Eu-MOFs are favorable adsorbents for the removal of U(VI), and interestingly, the functionalized Eu-BDC-SA exhibited very rapid (∼5 min) and high sorption efficiency, ca. ∼99% at pH 6. The utility of these functionalized Eu-MOFs was also investigated for the sensing of distinct fission product elements. Interestingly, fluorescence sensing studies of fission products along with U(VI) confirmed that these Eu-MOFs exhibited a high and selective sensing ability to detect Pd(II) from a pH 2 solution over other metal ions. However, Eu-BDC-NH₂ showed excellent sensing ability toward Pd(II) with a detection limit of 0.4 ppm. Additionally, we have investigated the nature of Pd(II) interactions on MOFs by applying density functional theory (DFT). The high binding energies obtained for the complexes between the ligand motifs and Pd²⁺ may be correlated with the high fluorescence quenching of the MOFs by palladium. The charge transfer interactions occurring within the complexes were also probed by natural bond orbital analysis. The work established here will pave the way for the extraction of U(VI) in the nuclear industry across various fields and will also greatly enhance the utility of these MOFs for the highly selective sensing of precious metal ions, such as Pd(II).