다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Ju Mei,†,‡,∥ Nelson L. C. Leung,†,‡,∥ Ryan T. K. Kwok,†,‡ Jacky W. Y. Lam,†,‡ and Ben Zhong Tang*,†,‡,§ †HKUST-Shenzhen Research Institute, Hi-Tech Park, Nanshan, Shenzhen 518057, China ‡Department of Chemistry, HKUST Jockey Club Institute for Advanced Study, Institute of Molecular Functional Materials, Division of Biomedical Engineering, State Key Laboratory of Molecular Neuroscience, Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Guangdong Innovative Research Team, SCUT-HKUST Joint Research Laboratory, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640, China

Aggregation-Induced Emission: Together We Shine, United We Soar!

Luminogenic materials with aggregation-induced emission (AIE) attributes have attracted much interest since the debut of the AIE concept in 2001. In this critical review, recent progress in the area of AIE research is summarized. Typical examples of AIE systems are discussed, from which their structure–property relationships are derived. Through mechanistic decipherment of the photophysical processes, structural design strategies for generating new AIE luminogens are developed. Technological, especially optoelectronic and biological, applications of the AIE systems are exemplified to illustrate how the novel AIE effect can be utilized for high-tech innovations (183 references).

Aggregation-induced emission

Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

Chemistry of Carbon Nanotubes

Two cyclic carbazolenevinylene dimers 1 and 2 were synthesized by McMurry coupling reactions. A linear compound 3 was also prepared for comparison. Compounds 1-3 were fully characterized by means of NMR spectroscopy, HRMS, elemental analysis, and UV/Vis absorption spectroscopy. Quantum chemical simulations showed that the cyclic compounds possessed smaller HOMO-LUMO gaps and more extended conjugation. The UV/Vis absorption spectra of the cyclic compounds showed blueshifts compared with that of the linear compound 3. Time-dependent DFT (TD-DFT) analysis revealed that this was due to the different selection rules for molecules with cyclic and linear architectures. The cyclic conformation also significantly affected the molecular ordering in the solid state. The X-ray crystal structure of 1 showed partial pi-pi overlapping between the adjacent molecules. Thin films of 1-3 were fabricated by the vacuum-deposition method on Si/SiO(2) substrates. Multicrystalline thin films were obtained from compounds 1 and 2, but only amorphous thin films could be obtained for the linear compound 3. Another important difference between the cyclic and linear compounds was the reduced reorganization energy for the cyclic compounds. These two facts have resulted in improved field-effect transistor (FET) mobilities for the cyclic compounds compared with the linear compound. In addition, as the substrate temperature has a significant influence on the morphology and the degree of crystallinity of the thin films deposited, the device performance could be optimized by varying the substrate temperature. The FET devices based on 2 gave the highest mobility of 0.013 cm(2) V(-1) s(-1). The results showed that carbazole derivatives with cyclic structures might make better FETs.

Synthesis, Characterization, and Field-Effect Transistor Properties of Carbazolenevinylene Oligomers : From Linear to Cyclic Architectures

A series of semiconducting copolymers incorporating dithieno[3,2-b:2′,3′-d]thiophene moieties in the polythiophene backbone were synthesized. The resulting four copolymers are found to have large band gap (∼ 2.5 eV) and large ionization potential (−5.1 eV). Organic field-effect transistors were fabricated by spin-coating polymer solutions onto OTS-modified SiO2/Si substrates with top-contact configuration. The best resulting hole mobility afforded was 0.028 cm2V−1 s−1 with an on/off ratio of 2 × 104 and a threshold voltage of about −18.9 V in the saturation regime. Furthermore, all the devices exhibited high environmental stability against oxygen doping and relatively high ambient humidity (∼30%).

Novel copolymers incorporating dithieno[3,2-b:2′,3′-d]thiophene moieties for air-stable and high performance organic field-effect transistors

Dicyanovinyl-substituted compounds as electron transport materials are rarely studied, especially oligomers. A new series of fluorene or carbazole-based and dicyanovinyl-capped oligomers consisting of benzene or thiophene segments were synthesized using the Stille coupling reaction and their physical properties were investigated. Optical spectra show that the introduction of electron-accepting groups induces an intramolecular charge transfer, resulting in a shift of the absorption onset toward longer wavelengths. Moreover, the optical spectra of their films show intermolecular interactions, leading to bathochromic shifts with respect to the spectra in solution. Cyclic voltammetry indicates that they have suitable HOMO and LUMO energy levels, and the oligomers containing thiophene segments show lower LUMO levels. The X-ray crystallography of compound FTCN shows that the compound exhibits extended π stacking of the molecules. Thermal analysis reveals that they are thermally stable and no phase transition was observed at low temperatures.

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Synthesis and properties of fluorene or carbazole-based and dicyanovinyl-capped n-type organic semiconductors

Three new fused-ring pyrazine derivatives end-functionalized with trifluoromethylphenyl groups have been synthesized. The effect of a fused-ring pyrazine core on the thermal, electronic, optical, thin film morphology, and organic field-effect transistor (OFET) properties was investigated both experimentally and theoretically. Electrochemistry measurements and density functional theory calculations suggest that the pyrazine core plays a significant role in tuning the electron affinities of these compounds. The optical absorption and fluorescence properties are also sensitive to the pyrazine core. The OFET devices based on the fused-ring pyrazine compounds exhibit electron mobilities as high as ca. 0.03 cm2 V−1 s−1 under nitrogen, and their performance is sensitive to the pyrazine core. The larger pyrazine core leads to a lower LUMO level and lower reorganization energy, to more ordered thin film morphology with larger grain size, and finally to higher mobilities.

Yunqi Liu

Papers

Synthesis, Characterization, and Field-Effect Transistor Properties of Carbazolenevinylene Oligomers : From Linear to Cyclic Architectures

Novel copolymers incorporating dithieno[3,2-b:2′,3′-d]thiophene moieties for air-stable and high performance organic field-effect transistors

Synthesis and properties of fluorene or carbazole-based and dicyanovinyl-capped n-type organic semiconductors

Fused-Ring Pyrazine Derivatives for n-Type Field-Effect Transistors

Novel Functionalized Conjugated Polythiophene with Oxetane Substituents: Synthesis, Optical, Electrochemical, and Field-Effect Properties