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121.
Single-step sol–gel deposition was attempted for realizing submicron thick, (001) oriented Pb(Zr0.53Ti0.47)O3 (PZT) thin films, using an alkoxide solution containing polyvinylpyrrolidone (PVP). A solution of molar composition, Pb(NO3)2:Zr(OC3H7
n)4:Ti(OC3H7
i)4:PVP:H2O:CH3COCH2COCH3:CH3OC2H4OH:C3H7
nOH = 1.1:0.53:0.47:0.5:5:0.5:22:0.98, was prepared as a coating solution. Gel films were prepared on Pt(111)/TiO2/SiO2/Si(100) substrates by spin-coating, and calcined at 350 °C and annealed at 650 °C either in an electric furnace or in a near-infrared
(IR) furnace. When calcined in the near-IR furnace, the films became (001) oriented on annealing. When calcined in the electric
furnace, on the other hand, the films became randomly oriented on annealing. These observations indicate that the heating
the gel films from the substrate side in the calcination step at 350 °C induces crystallographic orientation in the annealing
step at 650 °C. The effects of the heating methods on the thermal decomposition of the gel films, and the microstructure and
dielectric properties of the fired films were studied. Finally 0.4 μm thick, (001) oriented PZT films could be successfully
prepared by non-repetitive, single-step deposition. The oriented film thus obtained had the remnant polarization 2P
r of 39 μC/cm2 and the dielectric constant ε′ of 960 ± 169. 相似文献
122.
Maeda H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(36):11274-11282
Supramolecular gels that change their state or structure in response to anion stimuli have been highlighted. Only a few examples exist of such supramolecular gels, the structures and properties of which can be controlled and modulated by interactions with anions. To form anion-responsive dimensionally-controlled organized structures, the constituent low-molecular-weight gelator molecules must act as anion receptors by possessing one or more of van der Waals interaction units (aliphatic chains), stacking pi planes, hydrogen-bonding sites, and metal-coordination units. This Concept focuses on the gelation and transition behaviors of amide- and urea-based anion-stimulated systems, metal-coordinated systems, and novel acyclic pi-conjugated oligopyrroles that act as "molecular flippers." 相似文献
123.
Selective iodination at the alpha-pyrrole positions of dipyrrolyldiketone BF(2) complexes is a key procedure to afford mono- and bisiodinated derivatives as the starting materials of the coupling reactions for various utility molecules and covalently linked oligomer systems. Iodination can also be applied to the phenylene-bridging receptor dimer to obtain the derivatives selectively iodinated at the terminal alpha-pyrrole position(s). 相似文献
124.
Dr. Kazuhisa Yamasumi Kentaro Ueda Dr. Yohei Haketa Dr. Yusuke Hattori Prof. Masayuki Suda Prof. Shu Seki Dr. Hayato Sakai Prof. Taku Hasobe Ryoya Ikemura Prof. Yoshitane Imai Dr. Yukihide Ishibashi Prof. Tsuyoshi Asahi Dr. Kazuto Nakamura Prof. Hiromitsu Maeda 《Angewandte Chemie (International ed. in English)》2023,62(8):e202216013
Squarylium-based π-electronic cation with an augmented dipole was synthesized by methylation of zwitterionic squarylium. The cation formed various ion pairs in combination with anions, and the ion pairs exhibited distinct photophysical properties in the dispersed state, ascribed to the formation of J- and H-aggregates. The ion pairs provided solid-state assemblies based on cation stacking. It is noteworthy that complete segregation of cations and anions was observed in a pseudo-polymorph of the ion pair with pentacyanocyclopentadienide as a π-electronic anion. In the crystalline state, the ion pairs exhibited photophysical properties and electric conductivity derived from cation stacking. In particular, the charge-segregated ion-pairing assembly induces an electric conductive pathway along the stacking axis. The charge-segregated mode and fascinating properties were derived from the reduced electrostatic repulsion between adjacent π-electronic cations via dipole–dipole interactions. 相似文献
125.
Synthesis and anion binding properties of BF2 complexes of beta-tetraethyl-substituted dipyrrolyldiketones, with and without electron-withdrawing ethoxycarbonyl moieties at pyrrole alpha-positions, are reported. The substituents at pyrrole rings of these acyclic anion receptors are found to play a key role to control not only the polarization of binding sites (NH and CH) but also the relative stabilities of the preorganized conformations and the degrees of sterical repulsion, both of which notably affect the affinities for anions. 相似文献
126.
Maeda H Ito Y Kusunose Y Nakanishi T 《Chemical communications (Cambridge, England)》2007,(11):1136-1138
Synthesis of di-pyrrolyl-substituted pyrazoles (dpp) and anion binding studies in protonated form are reported. Dpp show [2 + 2] binding of trifluoroacetate in the solid state to afford nanometer- and micrometer-scale architectures. 相似文献
127.
128.
Haketa Y Sakamoto S Chigusa K Nakanishi T Maeda H 《The Journal of organic chemistry》2011,76(13):5177-5184
Dipyrrolyldiketone BF(2) complexes acting as acyclic anion receptors form supramolecular assemblies with structures and properties that are dependent on the pyrrole β-substituents. In particular, although β-alkyl substituents interfered with the formation of stable gel states, the introduction of fluorine moieties induced a stable supramolecular gel when compared to that of β-unsubstituted receptor. 相似文献
129.
Nakayama A Kogure N Kitajima M Takayama H 《Angewandte Chemie (International ed. in English)》2011,50(35):8025-8028
Right on Q: The first asymmetric total synthesis of (-)-huperzine-Q, which possesses six stereogenic centers and a spiroaminal moiety, has been achieved in 19 steps and 16.4?% overall yield. This synthesis involved a novel stereoselective Pauson-Khand reaction, a vinyl Claisen rearrangement, and a biomimetic spiroaminal formation. TBDPS=tert-butyldiphenylsilyl. 相似文献
130.