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991.
Dr. Hsiu‐Hui Chen Hsing‐An Lin Yin‐Hui Lai Shu‐Yu Lin Chien‐Hung Chiang Prof. Hsiu‐Fu Hsu Prof. Tzenge‐Lien Shih Dr. Jey‐Jau Lee Prof. Chien‐Chen Lai Ting‐Shen Kuo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(31):9543-9551
The theoretically predicted optimum length/breadth/width ratio for maximizing shape biaxiality was investigated experimentally by the facile and successful synthesis of cross‐shaped compound 3 , which showed enantiomeric nematic phase behavior. This cross‐like core structure could alternatively be viewed as two fused V‐shaped mesogens, which have recently immerged as a new direction in biaxial nematic research, at the bending tips that can act as a new structure for biaxial investigations. Whilst the thermal analysis data of compound 3 did not meet the expected theoretical values for biaxial nematics, surface‐induced biaxiality was evidenced by optical studies. Cluster‐size analysis within the nematic phase of compound 3 revealed the formation of meta‐cybotactic nematics, which approached the cluster sizes of cybotactic nematics. The split small‐angle 2D X‐ray diffraction patterns of magnetic‐field‐aligned samples indicated that the nematic phase was composed of small smectic C‐like clusters with the tilting of molecules within the clusters. The wide‐temperature‐range enantiomeric nematic phase of cross‐like compound 3 enabled the molecular skeleton to serve as an alternative skeleton to bent‐rod mesogens, which exhibited nematic phases with the potential competition of transitions to higher‐order liquid‐crystalline phases and crystallization, for future biaxial investigations. 相似文献
992.
Shih‐Chieh Lin Prof. Rong‐Ming Ho Chin‐Yen Chang Prof. Chain‐Shu Hsu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(29):9091-9098
Herein, two asymmetric chiral bent‐core molecules, 3‐[(4‐{[4‐(heptyloxy)benzoyl]oxy}benzoyl)oxy]‐phenyl‐4‐[(4‐{[(1R)‐1‐methylheptyl]oxy}benzoyl)oxy] benzoate (BC7R) and 3‐[(4‐{[4‐(heptyloxy)benzoyl]oxy}benzoyl)oxy]‐phenyl‐4‐[(4‐{[(1S)‐1‐methylheptyl]oxy}benzoyl)oxy] benzoate (BC7S), were synthesized to demonstrate control of the helicity of their self‐assembled hierarchical superstructures. Mirror‐imaged CD spectra showed a split‐type Cotton effect after the formation of self‐assembled aggregates of BC7R and BC7S, thereby suggesting the formation of intermolecular exciton couplets with opposite optical activities. Both twisted and helical ribbons with preferential helicity that corresponded to the twisting character of the intermolecular exciton couplet were found in the aggregates. The formation of helical ribbons was attributed to the merging of twisted ribbons through an increase in width to improve morphological stability. As a result, control of the helicity of hierarchical superstructures from the self‐assembly of bent‐core molecules could be achieved by taking advantage of the transfer of chiral information from the molecular level onto the hierarchical scale. 相似文献
993.
Lin YF Chen JH Hsu SH Hsiao HC Chung TW Tung KL 《Journal of colloid and interface science》2012,368(1):660-662
ZrO(2) nanoparticles were successfully fabricated via a facile hydrothermal process. The diameter and surface area of the as-prepared ZrO(2) nanoparticles were approximately 5-10 nm and 102 m(2)/g, respectively. For the first time, Zr atoms with partial positive charges in a Lewis acid ZrO(2) nanoparticle adsorbent were used for the adsorption of negatively charged phospholipids from Jatropha oil. The capacity for phospholipid adsorption using the ZrO(2) nanoparticles was better than that of commercial ZrO(2) powder due to the larger surface area of the ZrO(2) nanoparticles. Phospholipid removal makes Jatropha oil a potential oil for biofuel applications. 相似文献
994.
Synthesis of high-quality carbon nanodots from hydrophilic compounds: role of functional groups 总被引:1,自引:0,他引:1
A simple one-pot hydrothermal approach has been demonstrated for the preparation of highly water soluble and photoluminescent carbon nanodots (C-dots) from low-cost organic compounds. We found that the compounds incorporating amino and carboxylic acid groups are suitable for the preparation of highly photoluminescent and water-soluble C-dots. 相似文献
995.
A new azaphilonidal derivative, monapurpyridine A (MPA), has recently been isolated from the fermented products of Monascus purpureus NTU 568. The structure of MPA was elucidated by nuclear magnetic resonance (1H-NMR, 13C-NMR, COSY, HMQC, and HMBC) and other spectroscopic analyses. Biological evaluation revealed that MPA could induce cell death in human breast adenocarcinoma cells MCF-7, and it has no significant toxicity to normal mammary epithelial cells M10. The MTT assay and flow cytometric analysis were employed to investigate cell viability and cell cycle influenced by MPA. Moreover, we used Western blot and caspase activity assay to demonstrate the activation of caspase-3, -8 and -9 resulted from MPA. All evidence supported that MPA was suitable for developing into a chemotherapeutic or chemopreventive agent against breast cancer. 相似文献
996.
CJ Li SY Huang MY Wu YC Chen SF Tsang JH Chyuan HY Hsu 《Molecules (Basel, Switzerland)》2012,17(8):9348-9360
Corchorus olitorius L., is a culinary and medicinal herb, widely used as a vegetable in several countries in Asia. Many studies have shown that C. olitorius contains several antioxidants and exhibits anti-inflammatory and anti-proliferative activities in various in vitro and in vivo settings. Recently, C. olitorius has been approved for its antitumor activity; however, the underlying molecular mechanisms remain unclear. The goal of this study was to investigate the effects of ethanol extract of C. olitorius (ECO) on the growth of human hepatocellular carcinoma (HepG2) cells and gain some insights into the underlying mechanisms of its action. We found that HepG2 cells, treated with ECO for 24 h at a concentration higher than 12.5 μg/mL, displayed a strong reduction in cell viability, whereas normal FL83B hepatocytes were not affected. DNA fragmentation and nuclear condensation were evidenced by the increased subG1 population of ECO-treated HepG2 cells. ECO triggered the activation of procaspases-3 and -9 and caused the cleavage of downstream substrate, poly ADP-ribose polymerase (PARP), followed by down-regulation of the inhibitor of caspase-activated DNase (ICAD) signaling. Moreover, the increased release of cytochrome c from mitochondria with decreased membrane potential demonstrated the apoptosis induced through the caspases cascade. Our findings indicated that ECO might be effective against hepatocellular carcinoma through induction of apoptosis via mitochondria-dependent pathway. 相似文献
997.
Tu YJ Cheng HC Chao I Cho CR Cheng RJ Su YO 《The journal of physical chemistry. A》2012,116(6):1632-1637
Electrochemical properties of substituted free base meso-tetraphenylporphyrins (H(2)T(o,o'-X)PP, H(2)T(o-X)PP, and H(2)T(p-X)PP, where X = OCH(3), CH(3), H, F, or Cl on the phenyl rings) are examined by cyclic voltammetry. When a substituent is located only at the para position of the meso-phenyl group, the difference between the first and second oxidation potentials (ΔE(ox), i.e., E(2)(ox) - E(1)(ox)), is generally significantly smaller than those of the H(2)TPPs with bulky o,o'-substituents on the phenyl group. This trend is elucidated with density functional theory calculations and attributed mainly to the sterically controlled π-conjugation of the meso-phenyl groups to the central porphyrin ring, rather than the often discussed deformation of porphyrin. 相似文献
998.
Hsu IJ Kimmel YC Jiang X Willis BG Chen JG 《Chemical communications (Cambridge, England)》2012,48(7):1063-1065
Pt was deposited onto tungsten carbide powders using atomic layer deposition to produce core-shell catalysts for the hydrogen evolution reaction (HER). The Pt loading on these catalysts was reduced nearly ten-fold compared to a bulk Pt catalyst while equivalent HER activities were observed. 相似文献
999.
Cheng YJ Cheng SW Chang CY Kao WS Liao MH Hsu CS 《Chemical communications (Cambridge, England)》2012,48(26):3203-3205
We report a novel diindenothieno[2,3-b]thiophene ladder-type hexacyclic arene for constructing a donor-acceptor copolymer PDITTDTBT. A device based on PDITTDTBT:PC(71)BM exhibited a high V(oc) of 0.92 V with an impressive PCE of 5.8%, while a PDITTDTBT:DMPCBA-based device showed an extra high V(oc) of 1.14 V. 相似文献
1000.
GeO2 thin films were prepared by sol‐gel method on ITO/Glass substrate. The electrical and optical properties and the microstructures of these films were investigated with special emphasis on the effects of an annealing treatment in ambient air. The films were annealed at various temperatures from 500 °C to 700 °C. Structural analysis through X‐ray diffraction (XRD) and atomic force microscope (AFM) showed that surface structure and morphological characteristics were sensitive to the treatment conditions. The optical transmittance spectra of the GeO2/ITO/Glass were measured using a UV‐visible spectrophotometer. All films exhibited GeO2 (101) orientation perpendicular to the substrate surface where the grain size increased with increasing annealing temperature. The optical transmittance spectroscopy further revealed high transparency (over 70 %) in the wave range 400 – 800 nm of the visible region. At an annealing temperature level of 700 °C, the GeO2 films were found to possess a leakage current density of 1.31×10‐6A/cm2 at an electrical field of 20 kV/cm. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献