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Two‐dimensional (2D) materials exhibit unique electronic, optical, magnetic, mechanical, and thermal properties due to their special crystal structure and thus have promising potential in many fields, such as in electronics and optoelectronics. To realize their real applications, especially in integrated devices, the growth of large‐size single crystal is a prerequisite. Up to now, the most feasible way to achieve 2D single crystal growth is the epitaxy: growth of 2D materials of one or more specific orientations with single‐crystal substrate. Only when the 2D domains have the same orientation, they can stitch together seamlessly and single‐crystal 2D films can be obtained. In this view, four different epitaxy modes of 2D materials on various substrates are presented, including van der Waals epitaxy, edge epitaxy, step‐guided epitaxy, and in‐plane epitaxy focusing on the growth of graphene, hexagonal boron nitride (h‐BN), and transition metal dichalcogenide (TMDC). The lattice symmetry relation and the interaction between 2D materials and the substrate are the key factors determining the epitaxy behaviors and thus are systematically discussed. Finally, the opportunities and challenges about the epitaxy of 2D single crystals in the future are summarized. [ABSTRACT FROM AUTHOR]

We report the cyclic single-crystal-to-single-crystal transformation of three hydrogen-bonded organic frameworks (HOFs), induced by the change of temperature and humidity, which clearly reveals that the –SO3−and –NH2 groups in UPC-H7 and UPC-H8 facilitate the diffusion of water molecules into their anhydrous structures to form hydrous UPC-H9. Their proton conductivity was studied under different humidity at varying temperature, showing that the proton conductivity is closely related to water molecules entering the crystal structures arising from the hydrogen bonded reorganization in combination with the triaxial single-crystal proton conductivity tests. [ABSTRACT FROM AUTHOR]

Three new mixed-ligand coordination networks, [Cd2(ADDA)(bipy)(H2O)2]·2H2O (1), [Zn(ADDA)(bipy)0.5]·NMP·2H2O (2), and [Co(ADDA)(bip)(H2O)2]·H2O (3) (bipy = 4,4′-bipyridine, bip = 1,4-di(1H-imidazol-1-yl)benzene, H2ADDA = 3,3′-(anthracene-9,10-diyl)diacrylic acid), have been synthesized based on 3,3′-(anthracene-9,10-diyl)diacrylate acid and different N-donor ligands under solvothermal conditions, and structurally characterized by single-crystal X-ray diffraction analyses, infrared spectroscopy (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Topological analysis reveals that 1 features a rare 8-connected 3D ilc network with the point symbol of {4∧24.5.6∧3}; complex 2 possesses a 3D open framework based on the infinite Zn–(CO2) chain with the point symbol of {6∧2.8∧4}; while complex 3 shows a normal 2D 3-connected coordination network with hcb topology and the point symbol of {6∧3}. Besides, the luminescence properties of complexes 1 and 2 were also investigated. The results show that complex 2 bears rapid and selective sensing of Fe3+ in methanol suspension at room temperature. [ABSTRACT FROM AUTHOR]

ZnS nanotetrapods synthesized via a solvothermal route have a octahedral core with a zincblende (ZB) structure and four hexprism-shaped arms consisting of alternately stacking ZB and wurtzite (WZ) phases, where the WZ phase has a higher volume percentage.In situangular-dispersive X-ray diffraction (ADXRD) measurements were carried out to study the structural behavior of ZnS nanotetrapods under high pressure up to 41.3 GPa. The initial WZ structure exhibits a very high mechanical stability to ∼11.3 GPa. Both the WZ and ZB structures transform to the rocksalt (RS) structure at ∼15.4 GPa. The bulk moduli of the WZ (148.2 ± 8.9 GPa) and RS (165.6 ± 9.9 GPa) phases are both larger than the previously reported values. These phenomena are discussed based on the alternating epitaxial growth of the WZ and ZB phases in the arms of nanotetrapods. Our study suggests that the internal structure of nanomaterials could also greatly affect their stability and transition behavior. [ABSTRACT FROM PUBLISHER]

Nickel ferrite (NiFe2O4) nanomaterials with different morphologies, including nano-spheres (10–25 nm in diameter), nano-rods (50–60 nm in diameter and ~1 μm in length), and nano-octahedrons (side length ~150 nm), have been synthesized by a single mild hydrothermal method at 160 °C without any surfactant. The crystal structures have been investigated by TEM, HRTEM, and studied by simulations using the program Materials Studio. The variations in the morphology, as well as the preferential crystal growth directions, depend only on the pH value of the reaction solution. A phase formation mechanism is thus proposed. Magnetization measurements at T = 300 K indicate that the NiFe2O4 nano-spheres of 10–25 nm diameter are superparamagnetic with non-saturating magnetization at H = 7 kOe. The saturation magnetization, MS, of the nanorods is 40 emu g−1, less than the bulk value, MS = 46.7 to 55 emu g−1. The coercivity is HC = 40 Oe, reduced from the bulk value of 100 Oe. On the other hand, the nano-octahedrons have a saturation magnetization of MS = 50 emu g−1, the same as the bulk value. However the coercivity, HC = 50 Oe is also much reduced from the bulk value. [ABSTRACT FROM AUTHOR]

Abstract: ZnS nanomaterials at different dimensions, from nanoparticles, nanobelts to nanotetrapods have been synthesized in the same solvothermal system, which is kinetically controlled by ethylenediamine. Microscopy analysis reveals that the four arms of tetrapod are grown from Zn-terminated surfaces of an octahedral core by alternately stacking zinc blende and wurtzite structures along [111]/[0001] direction, while the ZnS nanobelts are self-assembled along [0001] direction by ultra-small wurtzite nanocrystals. These nanobelts can be transformed into their single-crystal counterparts and ZnO/ZnS heterostructures by thermal treatment. Uv–visible analysis demonstrates that the heterostructure presents a strain-induced staggered Type-II band structure. These investigation results suggest an efficient approach for phase-controlled synthesis of nanostructures in group II–VI semiconductors. [Copyright &y& Elsevier]

Abstract: A new dinuclear iron nitrosyl complex [Fe2(C14H12N3S)2(NO)4] (1) (C14H12N3S=2-mercapto-1-[2-(4-pyridyl)-ethyl]-benzimidazolyl) has been obtained by the reaction of Fe(NO)2(CO)2 with 2-mercapto-1-[2-(4-pyridyl)-ethyl]-benzimidazole in CH3OH under moderate condition. Complex 1 was characterized by IR, UV–vis, electrochemistry and single crystal X-ray diffraction. IR spectrum displays two strong characteristic NO stretching frequencies (ν NO) in solution and in solid state. Cyclic voltammetry shows one irreversible, two quasi-reversible and two reversible one-electron reductions and irreversible oxidizations. This result is consistent with the fact that complex 1 is very unstable and ready to lose NO in the air. As showing in the single crystal X-ray diffraction, complex 1 forms a “chair-shape” structure by the connections of two iron centers and S–C–N frames of benzimidazole. The dihedral angle of benzimidazole ring and 2Fe–2S plane is 73.6°. The crystal data are the following: 1, monoclinic, space group P2(1)/c, a =10.43940(10)Å, b =16.0900(2)Å, c =10.13240(10)Å, α =90°, β =111.0940(10)°, γ =90°, V =1587.89(3)Å3, Z =4. [Copyright &y& Elsevier]