1,721,096 research outputs found
Highly efficient growth of morphologically well-defined molecular crystals of phenothiazine using drop-drying method in a mixed solvent system
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"Selective Formation of Insulating/Electron Conductive Porous Coordination Networks Using Redox Active Ligand"
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Selective Formation of Conductive Network by Radical-Induced Oxidation
No full textCd-based coordination networks having channels were formed selectively by using a redox-active aromatic ligand 2,5,8-tri(4-pyridyl)1,3-diazaphenalene (TPDAP, H+1-). An electron-conductive network having a π-π stacking columnar structure of TPDAP formed in the presence of a trace amount of TPDAP radical (1•). In contrast, a nonconductive network having a dimer unit of H+1- formed in the absence of 1•. These results suggest the presence of a unique oxidation mechanism of TPDAP induced by formation of H+1--1• dimer, which was initiated by a trace amount of 1•. The dimerization increased HOMO level of H+1- moiety within the dimer to generate further radicals that could not form when H+1- was well isolated in CH3OH. © 2016 American Chemical Society1991sciescopu
Rapid, Resist-free Patterned Growth of Sea-Urchin-Shaped Hierarchical Porous Covalent Organic Framework-5 (COF-5) by Photochemical Synthesis Method
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Crystallisation of organic molecules with a remarkably suppressed coffee-ring effect by a drop-drying process using binary solvent core-shell droplets
No full textA core-shell drop-drying (CSDD) method that employs spontaneous formation of a droplet-in-droplet system was newly presented for the efficient formation of molecular crystals. Well-defined methylene blue crystals were successfully obtained from the core-shell droplet with a significantly diminished coffee-ring effect. © 2018 The Royal Society of Chemistr
High-Conductivity Two-Dimensional Polyaniline Nanosheets Developed on Ice Surfaces
No full textA new method to develop two-dimensional PANI nanosheets using ice as a removable hard template is presented. Distinctly high current flows of 5.5 mA at 1 V and a high electrical conductivity of 35 S cm-1 were obtained for the polyaniline (PANI) nanosheets, which marked a significant improvement from previously values on other PANIs reported over the past decades. These improved electrical properties of ice-templated PANI nanosheets were attributed to the long-range ordered edge-on π-stacking of the quinoid ring, ascribed to the ice surface-assisted vertical growth of PANI. The unprecedented advantages of the ice-templated PANI nanosheets are two-fold. First, the PANI nanosheet can be easily transferred onto various types of substrates via float-off from the ice surfaces. Second, PANI can be patterned into any shape using predetermined masks, and this is expected to facilitate the eventual convenient and inexpensive application of conducting polymers in versatile electronic device forms. A cool way to conduct: Ice is used as a removable hard template to form two-dimensional polyaniline (PANI) nanosheets. High current flows (5.5 mA at 1 V) and high electrical conductivity (35 S cm-1) were obtained for the nanosheets. The PANI nanosheet can be easily transferred onto various types of substrates from the ice surfaces, and the nanosheets can be patterned into any shape using predetermined masks. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim130281sciescopu
Broken-Symmetry Quantum Hall States in Twisted Bilayer Graphene
Full text linkTwisted bilayer graphene offers a unique bilayer two-dimensional-electron system where the layer separation is only in sub-nanometer scale. Unlike Bernal-stacked bilayer, the layer degree of freedom is disentangled from spin and valley, providing eight-fold degeneracy in the low energy states. We have investigated broken-symmetry quantum Hall (QH) states and their transitions due to the interplay of the relative strength of valley, spin and layer polarizations in twisted bilayer graphene. The energy gaps of the broken-symmetry QH states show an electron-hole asymmetric behaviour, and their dependence on the induced displacement field are opposite between even and odd filling factor states. These results strongly suggest that the QH states with broken valley and spin symmetries for individual layer become hybridized via interlayer tunnelling, and the hierarchy of the QH states is sensitive to both magnetic field and displacement field due to charge imbalance between layers. © The Author(s) 20161221sciescopu
Organobismuth Molecular Crystals for Organic Topological Insulators
No full textThree different types of large and high-quality organobismuth molecular crystals were grown by a physical vapor transport process. The target organobismuth molecules that have similar molecular structures, except for the type and position of the functional group, were crystallized into colorless and wire-shaped crystals having lengths at the centimeter scale with uniform flat surface. The crystal-packing structures of the organobismuth crystals were determined by single-crystal X-ray diffraction. The results show
that the molecular packing can be controlled by a slight change of the functional group due to their different intermolecular interactions. Especially, the Bi−Bi distance was successfully controlled to vary from 5.11(1) to 5.71(3) and 5.18(2) Å for triphenylbismuth (TPB), tri-p-tolylbismuthine (p-TTB), and tri-o-tolylbismuthine (o-TTB), respectively. The different crystal structures and Bi−Bi distances can affect the topological behavior of the materials. Moreover, the electrical and optical properties of the target organobismuth crystals were confirmed through the I−V characteristics, density functional theory calculation, and photoluminescence spectroscopy. These findings potentially offer a new route and strategy for the development of organic topological insulators.11Nsciescopu
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