Studies on Synthesis of a Cycloheptapeptide and Effects of Different Metal Ions on the Cyclization

ＩｎｔｒｏｄｕｃｔｉｏｎＣｙｃｌｉｃｐｅｐｔｉｄｅｓ ,ｗｈｉｃｈａｒｅｃｏｎｓｔｒａｉｎｅｄｃｏｎｆｏｒｍａ ｔｉｏｎａｌｌｙａｎｄｍｏｒｅｒｅｓｉｓｔａｎｔｔｏｐｒｏｔｅａｓｅｄｉｇｅｓｔｉｏｎｓｔｈａｎｔｈｅｉｒｌｉｎｅａｒｐｒｅｃｕｒｓｏｒｓ ,ｈａｖｅｂｅｅｎｏｆｇｒｅａｔｉｎｔｅｒｅｓｔａｓｓｙｎｔｈｅｔｉｃｔａｒｇｅｔｓｂｏｔｈａｓｐｏｔｅｎｔｉａｌｄｒｕｇｌｅａｄｓａｎｄａｓｍｏｄｅｌｓｆｏｒｃｏｎ ｆｏｒｍａｔｉｏｎａｌａｎａｌｙｓｉｓ .1 4 Ｃｕｒｒｅｎｔｍｅｔｈｏｄｓｆｏｒｓｙｎｔ…     

Investigation on False Peak Phenomena in On-line Sweeping Technique in MEKC

ＩｎｔｒｏｄｕｃｔｉｏｎＭｉｃｅｌｌａｒｅｌｅｃｔｒｏｋｉｎｅｔｉｃｃｈｒｏｍａｔｏｇｒａｐｈｙ (ＭＥＫＣ)ｗａｓｉｎｖｅｎｔｅｄｔｏｅｘｔｅｎｄｔｈｅｕｔｉｌｉｔｙｏｆｃａｐｉｌｌａｒｙｅｌｅｃｔｒｏｐｈｏｒｅｓｉｓ(ＣＥ)ａｎｄｐｅｒｍｉｔｔｅｄｔｈｅｓｅｐａｒａｔｉｏｎａｎｄａｎａｌｙｓｉｓｏｆｎｅｕｔｒａｌｃｏｍｐｏｕｎｄｓ .ＢｕｔｊｕｓｔｌｉｋｅｏｔｈｅｒｍｏｄｅｓｏｆＣＥ ,ＭＥＫＣａｒｅｈａｍｐｅｒｅｄｂｙｔｈｅｌｏｗｃｏｎｃｅｎｔｒａｔｉｏｎｓｅｎｓｉｔｉｖｉｔｙｏｆｔｈｅｕｌｔｒａ …     

Systematic Studies on Corelation Between Hydrophobic Constant P and Solute Physico-chemical Parameters

ＳｙｓｔｅｍａｔｉｃＳｔｕｄｉｅｓｏｎＣｏｒｅｌａｔｉｏｎＢｅｔｗｅｅｎＨｙｄｒｏｐｈｏｂｉｃＣｏｎｓｔａｎｔＰａｎｄＳｏｌｕｔｅＰｈｙｓｉｃｏ┐ｃｈｅｍｉｃａｌＰａｒａｍｅｔｅｒｓ＊ＢＡＩＪｉａｎ－ｅ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，Ｌ...     

Blue-light emitting diodes and flat display based on poly(p-phenylenevinylene) copolymers

Ｐｏｌｙｍｅｒｉｃｌｉｇｈｔｅｍｉｔｔｉｎｇｄｉｏｄｅｓ(ＬＥＤｓ)ｈａｖｅｄｒａｗｎｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔｉｏｎｆｏｒｔｈｅｉｒｐｏｓｓｉｂｌｅａｐｐｌｉｃａｔｉｏｎｓｉｎｌａｒｇｅａｒｅａｆｌａｔｐａｎｅｌｄｉｓｐｌａｙｓｉｎｃｅｔｈｅ1990ｓｗｈｅｎａｇｒｏｕｐａｔＣａｍｂｒｉｄｇｅＵｎｉｖｅｒｓｉｔｙ[1]ｒｅｐｏｒｔｅｄｔｈａｔｐｏｌｙ(ｐｐｈｅｎｙｌｅｎｅｖｉｎｙｌｅｎｅ)(ＰＰＶ)ｅｘｈｉｂｉｔｓｅｌｅｃｔｒｏｌｕｍｉｎｅｓｃｅｎｃｅ.Ｓｉｇｎｉｆｉｃａｎｔｉｍｐｒｏｖｅｍｅｎｔ…     

Investigation of HNO_3 Chemincally Oxidized Porous Silicon

ＩｎｖｅｓｔｉｇａｔｉｏｎｏｆＨＮＯ＿３ＣｈｅｍｉｎｃａｌｌｙＯｘｉｄｉｚｅｄＰｏｒｏｕｓＳｉｌｉｃｏｎＦｅｎｇＹＩＮ；ＸｕｅＰｉｎｇＬＩ；ＺｈｅｎＺｏｎｇＺＨＡＮＧ；ＴｉｅＦｅｎｇＣＨＥＮ；ＸｕＲｕｉＸＩＡＯ（Ｉｎｓｔｉｕｔｅｏｆｐｈｏｔｏｇｒａｐ...     

Study and Application of Polarographic Catalytic Wave of Chlordiazepoxide in the Presence of Persulfate

ＩｎｔｒｏｄｕｃｔｉｏｎＣｈｌｏｒｄｉａｚｅｐｏｘｉｄｅ (7 ｃｈｌｏｒｏ 2 ｍｅｔｈｙｌａｍｉｎｏ 5 ｐｈｅｎｙｌ 3Ｈ 1,4 ｂｅｎｚｏｄｉａｚｅｐｉｎｅ 4 ｏｘｉｄｅ)ｓｈｏｗｉｎｇｐｏｗｅｒｆｕｌａｎ ｔｉａｎｘｉｅｔｙｅｆｆｅｃｔｈａｓｂｅｅｎｗｉｄｅｌｙｕｓｅｄａｓａｐｓｙｃｈｏｔｈｅｒａｐｅｕ ｔｉｃｄｒｕｇ .Ｃｏｎｓｅｑｕｅｎｔｌｙ ,ｔｈｅｎｅｅｄａｒｏｓｅｆｏｒｓｅｎｓｉｔｉｖｅａｎｄｒａｐｉｄｄｅｔｅｒｍｉｎａｔｉｏｎｏｆｃｈｌｏｒｄｉａｚｅｐｏｘｉｄｅｉｎｂｌｏｏｄ ,ｕｒｉｎｅａｎ…     

最新电化学技术应用文献摘引

能量储存与转移用于锂电池的层状ｘＬｉＭＯ2 ·( 1 -ｘ)Ｌｉ2 Ｍ′Ｏ3 电极 :0 .95ＬｉＭｎ0 .5Ｎｉ0 .5Ｏ2·0 .0 5Ｌｉ2 ＴｉＯ3 的研究　Ｋｉｍ ,Ｊ .＿Ｓ .;Ｊｏｈｎｓｏｎ ,Ｃ .Ｓ .;Ｔｈａｃｋｅｒａｙ ,Ｍ .Ｍ . ,ＥｌｅｃｔｒｏｃｈｅｍｉｓｔｒｙＣｏｍｍｕｎｉｃａｔｉｏｎｓ ,2 0 0 2 ,4( 3) ,2 0 5～ 2 0 9一种作为锂嵌入电极新的聚吡咯 /磁赤铁混合物　Ｋｗｏｎ ,Ｃｈａｉ＿Ｗｏｎ ;Ｐｏｑｕｅｔ ,Ａｒｍｅｌ;Ｍｏｒｎｅｔ,Ｓｔ啨ｐｈａｎｅ ;Ｃａｍｐｅｔ ,Ｇｕｙ ;Ｐｏｒｔｉｅｒ ,Ｊｏｓｉｋ ;Ｃｈｏｙ ,Ｊｉｎ＿Ｈｏ ,Ｅ…     

INDOStudiesonElectronicStructuresof（C＿8H＿8）Ln（2，4－C＿4H＿11）（THF）（Ln＝Nd，Sm，Er）

ＩＮＤＯＳｔｕｄｉｅｓｏｎＥｌｅｃｔｒｏｎｉｃＳｔｒｕｃｔｕｒｅｓｏｆ（Ｃ＿８Ｈ＿８）Ｌｎ（２,４－Ｃ＿４Ｈ＿１１）（ＴＨＦ）（Ｌｎ＝Ｎｄ,Ｓｍ,Ｅｒ）ＷＡＮＧＺｈｉ－ｚｈｏｎｇ＊,ＦＥＮＧＪｉａｎ－ｎａｎ,ＺＨＡＮＧＳｏ－ｂｏａｎｄＬＩＵＪｕ－ｚｈ...     

Ab initio Calculation and Kinetic Study for the Abstraction Reaction of H with Sihcl3

ＴｒｉｃｈｌｏｒｏｓｉｌａｎｅｉｓａｎｉｍｐｏｒｔａｎｔｍａｔｅｒｉａｌｉｎｐｌａｓｍａＣｈｅｍｉｃａｌＶａｐｏｒＤｅｐｏｓｉｔｉｏｎ (ＣＶＤ)ａｎｄｉｎｓｅｍｉｃｏｎｄｕｃｔｏｒｄｅｖｉｃｅｐｒｏｃｅｓｓ .1 4 Ｔｈｅｒｅａｃｔｉｏｎｏｆｔｒｉｃｈｌｏｒｏｓｉｌａｎｅｗｉｔｈａｔｏｍｉｃｈｙｄｒｏｇｅｎ ,ｔｈｅｓｉｍｐｌｅｓｔｆｒｅｅ ｒａｄｉｃａｌｓｐｅｃｉｅｓ,ｈａｓｄｒａｗｎｃｏｎｓｉｄｅｒａｂｌｅａｔｔｅｎｔｉｏｎ :ｋｉｎｅｔｉｃｐａｒａｍｅｔｅｒｓｆｏｒＨ ａｔｏｍｒｅａｃｔｉｏｎａｒｅｄ…     

EHMO Studies of Chemisorbed Dioxygen Species on Na＿2O and K＿2O and of Their Interaction with CH＿4 and CH＿3－Radical

ＥＨＭＯＳｔｕｄｉｅｓｏｆＣｈｅｍｉｓｏｒｂｅｄＤｉｏｘｙｇｅｎＳｐｅｃｉｅｓｏｎＮａ＿２ＯａｎｄＫ＿２ＯａｎｄｏｆＴｈｅｉｒＩｎｔｅｒａｃｔｉｏｎｗｉｔｈＣＨ＿４ａｎｄＣＨ＿３－ＲａｄｉｃａｌＳＵＱｉａｏ－Ｊｕａｎ,ＺＨＡＮＧＨｏｎｇ－ｂｉｎ,ＺＨ...     

Scanning tunneling microscope imaging of (CH3S)2 on Cu(111)

Scanning tunneling microscope (STM) images of isolated molecules of dimethyl disulfide, (CH(3)S)(2), adsorbed on the Cu(111) surface were successfully obtained at a sample temperature of 4.7 K. A (CH(3)S)(2) molecule appears as an elliptic protrusion in the STM images. From density functional theory calculation, it was suggested that the bright part in the protrusion corresponds to the molecular orbital which is widely spread around H atoms in each CH(3) group in the (CH(3)S)(2) molecule. The STM images revealed that the molecules have a total of six equivalent adsorption orientations on Cu(111), which are given by the combination of three equivalent adsorption sites and two conformational isomers for each adsorption site.     

Imaging fibrinogen adsorbed on noble metal surfaces with scanning tunneling microscopy: correlation of images with electron spectroscopy for chemical analysis, secondary ion mass spectrometry, and radiolabeling studies

Fibrinogen adsorption on gold and platinum surfaces has been studied with electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectrometry (SIMS), ¹²⁵I labeling, and scanning tunneling microscopy (STM). Stable images of single molecules have been obtained, but are rare. ESCA, SIMS, and labeling studies confirm that absorbed fibrinogen is present on samples at monolayer and submonolayer coverages even when STM images show only a bare substrate. Imaging is more reproducible at high coverages at which single molecules cannot be resolved. Possible explanations for the failure of STM to observe adsorbed fibrinogen molecules are discussed.     

Imaging and vibrational spectroscopy of single pyridine molecules on Ag(110) using a low-temperature scanning tunneling microscope

A scanning tunneling microscope (STM) was used to extract the images of single, isolated pyridine molecules adsorbed on Ag(110) and to record their vibrational spectrum at 13 K. On the STM image, the pyridine molecule appears as an elongated protrusion along the [001] direction on top of a silver atom, indicating that it is bonded through its nitrogen lone pair electrons. STM inelastic electron tunneling spectroscopy of the adsorbed pyridine revealed C-D and C-H stretch modes at 282 and 378 meV, respectively.     

Scanning tunneling microscopy study of DNA-chromophore motif on solid surfaces

We focus our studies on DNA-chromophore motif on surfaces using samples prepared by the synthetic methods described by Wang and Li in a recent publication (J. Am. Chem. Soc. 2003, 125, 5248-5249). Scanning tunneling microscope (STM) was used to investigate the DNA-chromophore hybrids adsorbed on Au(111) and highly oriented pyrolytic graphite (HOPG) surfaces at room temperature in air. Experiments found that the DNA-chromophore hybrid molecules easily formed multimolecule aggregations on gold surface. On HOPG surfaces, however, DNA-chromophore hybrids were usually adsorbed as single molecules. STM images further showed DNA-chromophore hybrids adsorbed on Au(111) surfaces existed in the form of single molecule, dimer, trimer, tetramer, etc. The occurrence of molecular aggregations indicates that molecular interactions are comparable or stronger than molecule-substrate interactions; such weak interactions control the geometrical sizes and topographical shapes of the self-assembled DNA-chromophore hybrids on surfaces.     

Investigation of the scanning tunneling microscopy image, the stacking pattern, and the bias-voltage-dependent structural instability of 1,10'-phenanthroline molecules adsorbed on Au(111) in terms of electronic structure calculations

A self-assembled monolayer of 1,10'-phenanthroline (phen) molecules on Au(111) was found to undergo a structural phase transition when the bias voltage is switched in scanning tunneling microscopy (STM) experiments (Phys. Rev. Lett. 1995, 75, 2376; Surf. Sci. 1997, 389, 19). The nature of two bright spots representing each phen molecule in the high-resolution STM images of phen molecules on Au(111) was identified by calculating the partial density plots for a monolayer of phen molecules adsorbed on Au(111) with tight-binding electronic structure calculations. The stacking pattern of chains of phen molecules on Au(111) was explained by studying the intermolecular interactions between phen molecules on the basis of first-principles electronic structure calculations for a phen dimer, (phen)(2). The structural instability of phen molecule arrangement caused by the bias-voltage switch was probed by estimating the adsorbate-surface interaction energy with the point-charge approximation for Au(111).     

STM studies of photochemistry and plasmon chemistry on metal surfaces

We review our recent studies of photochemistry and plasmon chemistry of dimethyl disulfide, (CH₃S)₂, molecules adsorbed on metal surfaces using a scanning tunneling microscope (STM). The STM has been used not only for the observation of surface structures at atomic spatial resolution but also for local spectroscopies. The STM combined with optical excitation by light can be employed to investigate chemical reactions of single molecules induced by photons and localized surface plasmons. This technique allows us to gain insights into reaction mechanisms at a single molecule level. The experimental procedures to examine the chemical reactions using the STM are briefly described. The mechanism for the photodissociation reaction of (CH₃S)₂ molecules adsorbed on metal surfaces is discussed based on both the experimental results obtained with the STM and the electronic structures calculated by density functional theory. The dissociation reaction of the (CH₃S)₂ molecule induced by the optically excited plasmon in the STM junction between a Ag tip and metal substrate is also described. The reaction mechanism and pathway of this plasmon-induced chemical reaction are discussed by comparison with those proposed in plasmon chemistry.     

烷基链长对紫精分子在Cu(100)电极表面吸附结构的影响

用循环伏安法(CV)和原位扫描隧道显微镜(STM)研究了烷基取代的紫精分子在Cu(100)电极上的氧化还原行为及其吸附结构对电极电势的依赖性. 对乙基紫精(DHV)和庚基紫精(DEV)在含有KCl电解质溶液中进行循环伏安曲线的测定, 两者呈现出不同的氧化还原行为. 从STM所得图像观察, 二价庚基紫精在Cl-c(2×2)-Cu(100)电极上呈现出二维有序的点阵组装结构,而二价乙基紫精却未出现任何的吸附结构. 降低电极电势至单电子转移反应发生时, 形成的自由基庚基紫精在电极表面呈现出稳定的条带状组装结构, 而自由基乙基紫精出现的条带组装结构比较密集且不能稳定存在. 继续降低电极电势, 庚基紫精的吸附结构会随之出现明显的变化,而乙基紫精不会有吸附结构改变的响应.     

Au(111)表面Verdazyl自由基的构象转换

Pure organic radical molecules on metal surfaces are of great significance in exploration of the electron spin behavior. However, only a few of them are investigated in surface studies due to their poor thermal stability. The adsorption and conformational switching of two verdazyl radical molecules, namely, 1, 5-biisopropyl-3-(benzo[b]benzo[4,5]thieno[2, 3-d]thiophen-2-yl)-6-oxoverdazyl (B2P) and 1, 5-biisopropyl-3-(benzo[b]benzo[4,5]thieno[2, 3-d]thiophen-4-yl)-6-oxoverdazyl (B4P), are studied by scanning tunneling microscopy (STM) and density functional theory (DFT). The adsorbed B2P molecules on Au(111) form dimers, trimers and tetramers without any ordered assembly structure in which two distinct appearances of B2P in STM images are observed and assigned to be its "P" and "T" conformations. The "P" conformation molecules appear in the STM image with a large elliptical protrusion and two small ones of equal size, while the "T" ones appear with a large protrusion and two small ones of different size. Likewise, the B4P molecules on Au(111) form dimers at low coverage, strip structure at medium coverage and assembled structure at high coverage which also consists of above-mentioned two conformations. Both B2P molecules and B4P molecules are held together by weak intermolecular interaction rather than chemical bond. STM tip induced conformational switching of both verdayzl radicals is observed at the bias voltage of +2.0 V. The "T" conformation of B2P can be switched to the "P" while the "P" conformation of B4P can be switched to the "T" one. For both molecules, such a conformational switching is irreversible. The DFT calculations with Perdew-Burke-Ernzerhof version exchange-correlation functional are used to optimize the model structure and simulate the STM images. STM images of several possible molecular conformations with different isopropyl orientation and different tilt angle between verdazyl radical and Au(111) surface are simulated. For conformations with different isopropyl orientation, the STM simulated images are similar, while different tilt angles of verdazyl radical lead to significantly different STM simulated images. Combined STM experiments and DFT simulations reveal that the conformational switching originates from the change of tilting angle between the verdazyl radical and Au(111) surface. The tilt angles in "P" and "T" conformations are 0° and 50°, respectively. In this study, two different adsorption conformations of verdazyl radicals on the Au(111) surface are presented and their exact adsorption structures are identified. This study provides a possible way to study the relationship between the electron spin and configuration conversion of pure organic radical molecules and a reference for designing more conformational switchable radical molecules that can be employed as interesting molecular switches.     

Chemical reactions and adsorption geometries of pyrrole on Ge(100)

The adsorption structures of pyrrole (C(4)H(5)N) on a Ge(100) surface at various coverages have been investigated with both scanning tunneling microscopy (STM) and ab initio density-functional theory (DFT) calculations. Three distinct features are observed in the STM images at low coverages. The comparison of the STM images with the simulation reveals that the most dominant flowerlike feature with a dark side is that the adsorbed pyrrole molecules with H dissociated form bridges between two down Ge atoms of neighboring Ge dimer rows through N-Ge bonding and beta-carbon-Ge interaction. The flowerlike feature without a dark side is also observed as a minority, which is identified as nearly the same structure as the most dominant one where a dissociated H is out of the feature. The third feature showing bright protrusions may be due to a C- and N-end-on (CN) configuration, where the pyrrole molecule is located on one dimer row. At higher coverages, the number of localized configurations increases.     

Specific ethene surface activation on silver oxide covered Ag[111] from the interplay of STM experiment and theory

High-resolution scanning tunneling microscopy (STM) images at 5 K, simultaneously resolving the molecular adsorbate and the honeycomb structure of the well-defined Ag[111]-p(4 x 4)+Ag(1.83)O substrate, assign the adsorption site for ethene on the silver oxide surface. Ethene molecules are exclusively adsorbed above a particular subset of Ag(delta)(+) sites in the hexagonal rings of the oxide. Extensive density functional theory (DFT) slab calculations confirm that this is the most stable site, with an adsorption energy of 0.4 eV (39 kJ mol(-1)). Adsorption is accompanied by a large deformation of the hexagonal oxide ring and a significant increase in the C-C bond length. STM image simulations provide qualitative agreement with the experimental images, and the molecular orientation is discussed with the help of simple molecular orbital arguments.