Molecular and nanoscale materials and devices in electronics

Over the past several years, there have been many significant advances toward the realization of electronic computers integrated on the molecular scale and a much greater understanding of the types of materials that will be useful in molecular devices and their properties. It was demonstrated that individual molecules could serve as incomprehensibly tiny switch and wire one million times smaller than those on conventional silicon microchip. This has resulted very recently in the assembly and demonstration of tiny computer logic circuits built from such molecular scale devices. The purpose of this review is to provide a general introduction to molecular and nanoscale materials and devices in electronics.     

SiO2包覆纳米CaCO3的透射电镜表征

在透射电子显微镜（TEM）电子衍射模式下，用适当孔径的物镜光阑选择非晶态SiO2的衍射区域，拍摄以溶胶一凝胶法制备的SiO2包覆纳米CaCO3的暗场像。与未经包覆SiO2的纳米CaCO3的暗场像作对比，可以看出经过SiO2包覆的纳米CaCO3粒子周围有一白色亮环，从而得到SiO3包覆层的暗场照片。用高分辨方法观察了包覆层与CaCO3粒子间的界面情况。     

Silica-supported Copper（Ⅱ） Catalyzed Coupling of Arylboronic Acids with Imidazoles

Immobilized copper（Ⅱ） in organic-inorganic hybrid materials catalyzed Ar-N coupling of arylboronic acids with imidazoles has been developed. Arylboronic acids reacted with imidazoles smoothly in the presence of a 3-（2-aminoethylamino）propyl functionalized silica gel immobilized copper（Ⅱ） catalyst （10 mol%） in methanol without any additives and bases. The reactions generated the corresponding cross-coupling products in good yields. Furthermore, silica-supported copper can be recovered and recycled by a simple filtration procedure and used for five consecutive trials without decreases in activity.     

Microwave- and photoirradiation-induced staudinger reactions of cyclic imines and ketenes generated from alpha-diazoketones. A further investigation into the stereochemical process

Reactions of ketenes generated from alpha-diazoketones with a series of acyclic and cyclic imines were investigated under both microwave and photoirradiation conditions. The results indicate that the zwitterionic azabutadiene-type intermediates yielded from imines and ketenes undergo a conrotatory ring closure exclusively to produce beta-lactams. It is notable that no Woodward-Hoffmann product was found under the ultraviolet irradiation. The photoirradiation-induced Staudinger reaction shows a different stereoselectivity from the electrocyclic reaction of substituted 1,3-butadiene.     

Design and Synthesis of Paromomycin Related Heterocyclic Aminogly coside Mimetics Based on the Mass Spectroscopy RNA Binding Assay

Aminoglycoside antibiotics are known to interact with a variety of RNA molecules, including ribosomal RNA, and the hammerhead ribozyme. These low molecular weight antibiotics have also been found to block the binding of HIV-1 Rev protein to its viral RNA recognition site, thereby inhibiting the production of the virus. But due to their toxicity, poor bioavailability, cellular penetration, and instability, they can not be used as an inhibitory drug direct ly. Therefore, it is highly desirable to synthesize aminoglycoside mimetics, which may be less toxic and more active than original aminoglycosides.     

双亲半柔性两嵌段共聚物在溶液中自组装形态的模拟退火研究

针对一系列疏溶剂嵌段与溶剂间的相互作用,用模拟退火方法研究了双亲半柔性两嵌段共聚物在溶液中的自组装形态.模拟结果显示共聚物在溶液中均形成核-壳聚集体,其中疏溶剂嵌段形成聚集体的核,亲溶剂嵌段形成聚集体的壳.当上述相互作用较小时,核呈球形,而壳如同长在核上的刺.随着上述相互作用的增大,核逐渐增大.在较大的相互作用时,核呈柱形;而随着相互作用的加大,长在核上的刺逐渐伏贴于核表面.在更大的相互作用时,核又呈球状,壳伏贴于核表面.     

Molecular films of water-miscible ionic liquids formed on glassy carbon electrodes: characterization and electrochemical applications

This letter describes the formation and possible electrochemical applications of molecular films of water-miscible imidazolium-based ionic liquids (ILs) on glassy carbon (GC) electrodes. X-ray photoelectron spectroscopy (XPS) and electrochemical results indicate that the water-miscible ILs used in this study can interact with the GC electrode and form molecular films on the electrode surface. The formed molecular films are found to possess striking electrochemical properties such as electrocatalysis toward ascorbic acid (AA) and the capability to facilitate direct electron transfer of horseradish peroxidase (HRP). This demonstration would pave the way for new electrochemical applications of water-miscible ILs and is envisaged to be useful for the investigation of the electrochemical properties of water-miscible ILs in aqueous media provided the same counteranion is used as the supporting electrolyte.     

过硼酸钠对于有机物的氧化作用的研究 II: 氧化偶氮硝基苯类的合成

作者曾报道过硼酸钠在醋酸溶液中可使芳氨基氧化成硝基;McKillop等曾报道将过硼酸钠用于官能团的氧化;Huestis曾报道在冰醋酸溶液中用过硼酸钠将芳胺氧化成偶氮苯。这些都表明过硼酸钠是一种优良的氧化剂,反应条件温和、选择性强、氧化剂本身。价廉且其还原后所生成的硼酸钠易于处理和排放。因此,值得深入研究其应用范围。我们在此则报道一组以过硼酸钠为氧化剂,使芳胺氧化成氧化偶氮苯的条件。最近我们发现,在乙醇-磷酸体系中,过硼酸钠能顺     

Chemoenzymatic Synthesis of Cellular Adhesion Tripeptide RGD Precursor in Organic Media

IntroductionA characteristic tripeptide sequence Arg-Gly-Asp(RGD) that is found within fibronectin and other rela-ted adhesion molecules in extracellular matrices(ECM)has received considerable attention from researcherssince it was proved to be a recognit…     

Fluorescence-dip infrared spectroscopy and predissociation dynamics of OH A 2Sigma+ (v = 4) radicals

Fluorescence-dip infrared spectroscopy, an UV-IR double-resonance technique, is employed to characterize the line positions, linewidths, and corresponding lifetimes of highly predissociative rovibrational levels of the excited A (2)Sigma(+) electronic state of the OH radical. Various lines of the 4 <--2 overtone transition in the excited A (2)Sigma(+) state are observed, from which the rotational, centrifugal distortion, and spin-rotation constants for the A (2)Sigma(+) (v = 4) state are determined, along with the vibrational frequency for the overtone transition. Homogeneous linewidths of 0.23-0.31 cm(-1) full width at half maximum are extracted from the line profiles, demonstrating that the N = 0 to 7 rotational levels of the OH A (2)Sigma(+) (v = 4) state undergo rapid predissociation with lifetimes of < or =23 ps. The experimental linewidths are in near quantitative agreement with first-principles theoretical predictions.