紫外激光诱导C60与M(CO)6(M=Cr,Mo, W)的配位反应

研究了用紫外激光(355 nm)诱导C_(60)与金属羰基化合物M(CO)_6(M＝Cr；Mo，W)的配位反应，合成了具有C_(4υ)对称性的配位络合物(η~2－C_(60))M(CO)_5，并初步讨论了C_(60)与M(CO)_6反应的动力学过程．     

紫外光照下C_(60)与聚苯乙烯直接反应合成C_(60)-聚苯乙烯衍生物及电子自旋共振（ESR）研究

在室温，紫外光照下溶液相中C_(60)与聚苯乙烯的直接反应合成得聚苯乙烯的 C_(60)加合物。衍生物中C_(60)的含量可由C_(60)的投料比来控制。得到了产物经 UV－Vis，FTIR，GPC，TGA及DSC等波谱表片，测得产物的分子量比母体聚苯乙烯的 分子量稍高。对溶液相的反应进行了现场的ESR研究，得到强的PSC_(60)~(-·)的 自由基信号，g值为2.0024。同时对C_(60)和聚苯乙烯混合物固相体系的光照反应 进行了ESR测试。结果表明在反应过程中及最终产物中均存在稳定的C_(60)-高分子 链烃基自由基阴离子RC_(60)~(-·)。表明了反应的自由基机理。     

结晶性和粒子尺寸对C60薄膜晶体管迁移率的影响

采用真空沉积方法在不同基片温度(30~190℃)和沉积压力(1×10~(-4)和1×10~(-1) Pa)下制得了C_(60)薄膜。研究了薄膜的结晶性和晶粒尺寸对迁移率的影响。采用X射线衍射和原子力显微镜表征了薄膜的结构和形貌,发现提高基片温度,薄膜的结晶性和晶粒尺寸均提高;提高沉积压力,薄膜的晶粒尺寸增大而结晶性不变。场效应测试结果表明,C_(60)薄膜的迁移率与其结晶性密切相关,高的结晶性有利于获得高迁移率;不同于平面有机半导体材料,对于球状C_(60)半导体材料,大的晶粒尺寸可能导致低迁移率。     

紫外光照下C_(60)与聚苯乙烯直接反应合成C_(60)-聚苯乙烯衍生物及电子自旋共振（ESR）研究

在室温，紫外光照下溶液相中C_(60)与聚苯乙烯的直接反应合成得聚苯乙烯的 C_(60)加合物。衍生物中C_(60)的含量可由C_(60)的投料比来控制。得到了产物经 UV－Vis，FTIR，GPC，TGA及DSC等波谱表片，测得产物的分子量比母体聚苯乙烯的 分子量稍高。对溶液相的反应进行了现场的ESR研究，得到强的PSC_(60)~(-·)的 自由基信号，g值为2.0024。同时对C_(60)和聚苯乙烯混合物固相体系的光照反应 进行了ESR测试。结果表明在反应过程中及最终产物中均存在稳定的C_(60)-高分子 链烃基自由基阴离子RC_(60)~(-·)。表明了反应的自由基机理。     

C60的化学反应性和高分子化

综述了C_(60)化学研究的进展。C_(60)的化学反应性的研究展现了一个广阔的新领域,并使C_(60)作为一种新型的功能基团引入高分子成为现实。这些进展为进一步深入研究C_(60)尤其是C_(60)的材料化提供了前提。     

不同质量Cn笼电子结构和UV谱的理论研究

用INDO/2和INDO/CI方法研究了C_(24)、C_(50)、C_(60)和C_70的电子结构和UV谱。稳定性的顺序为C_(60)～C_(70)>C_(50)>>C_(24)。以C_(60)为中心向两边的C_n原子簇,其UV谱发生红移。     

C60电化学还原的稳态性质研究

自1990年9月Kratschmer等报导了C_(60)的常量制备和提纯以来,有关C_(60)及其他富勒炭分子(Fullerens)的研究报导与日俱增,成为近三年来最为活跃的研究领域之一.由于C_(60)的特殊结构,在电化学行为上也表现出十分独特的反应性质,如容易实现多电子氧化还原反应,可逆加氢及能形成离子嵌入电极材料等.本工作采用微电极方法研究了C_(60)稳态极化行为,测定了C_(60)的扩散系数和反应电子数,并通过现场紫外可见光谱电化学方     

C60衍生物的MALDI-TOFMS分析

C_(60)衍生物在超导、非线性光学、催化、材料和生物活性等方面有巨大的潜在应用价值。C_(60)衍生物大多为固体,蒸汽压较低,采用需要加热才能够使样品气化电离的质谱或"硬"电离质谱方法进行测定,易造成C_(60)衍生物分解并释放出配体。近年来国内外应用基体辅助激光解吸软电离质谱法成功分析了许多不同类型的C_(60)衍生物如卤化C_(60)酰胺化C_(60)芳基化C_(60)、C_(60)部花菁、煤基C_(60)烟灰萃取产物、金属C_(60)衍生物以及C_(60)乙二胺膜等。本文报道采用MALDI-TOFMS法分析C_(60)酯衍生物和C_(60)吡咯烷衍生物的结果。     

C_(60)及其碱金属衍生化合物

本文综述了C_(60)的分子结构,合成,晶体结构和相变,主要物理化学性能,以及碱金属C_(60)化合物M_3C_(60),M_4C_(60)和M_6C_(60)的制备,晶体结构和超导性。     

C_(60)在高压条件下可转变为金刚石

法国格林诺伯(Grenoble)极低温研究中心的Regueiro和P.Monceau、J.L.Hodeau已经证实,在室温条件下对C_(60)对称性足球状分子快速施加20GPa的压力而非静压力时,大量的C_(60)即刻转变为多晶金     

How different are diastereomorphous orientations of enantiomers in the liquid crystalline phases of PBLG and PBDG: a case study

The orientational properties of the two enantiomers of an example compound, namely isopinocampheol [(+)‐ and (?)‐IPC] in the two enantiomers of a liquid crystalline phase, namely Poly‐γ‐benzyl‐L/D‐glutamate (PBLG/PBDG) with the organic cosolvent CDCl₃, were investigated. The interactions can be either enantiomorphous, leading to equal orientations and residual dipolar couplings (RDCs), or diastereomorphous, leading to different orientations and RDCs. The difference between the two diastereomorphous orientations was determined to be rather small (5° in the Euler angle β). Furthermore, we investigated whether one of the two diastereomorphous interactions is favored. Copyright © 2009 John Wiley & Sons, Ltd.     

Orientational transitions in an adsorption layer of inter-acting molecules

The behaviour of an adsorption system of interacting organic molecules present on the surface in two different orientations is discussed. The influence of the ratio between attraction constants for various orientations on the function linking coverage to the bulk adsorbate concentration is examined. It is shown that according to the ratio of the isotherm parameters one or two orientational transitions may be predicted. The critical conditions for abrupt reorientations are obtained.     

Real-time dipole orientational imaging as a probe of ligand-protein interactions

Single-molecule orientational imaging using total internal reflection fluorescence microscopy has been employed to investigate the dynamics of a protein-ligand system. Emission patterns from single tetramethylrhodamine (TMR)-biocytin molecules bound to streptavidin show that the TMR dipole adopts a limited number of favored orientations. The angular trajectories of individual dipoles exhibit remarkably similar patterns that are characteristic of single TMR molecules interacting with a relatively homogeneous population of nanoenvironments. Analysis of the polar and azimuthal angle distributions reveals a tendency for the dipole to assume three primary and two secondary orientations. Autocorrelation analysis of the dipole trajectories shows a predominantly bimodal behavior in the reorientation rates with the slow and fast components corresponding to the primary and secondary orientations, respectively. A number of mechanisms by which the observed orientations might be stabilized have been considered, in particular specific interactions between the zwitterionic TMR probe and charged residues on the streptavidin surface. Variations in the reorientation rates have been discussed in terms of local thermal fluctuations in the protein.     

Conformational studies of the β(1→3) linked disaccharide component of the immunologically active pentasaccharide of the Forssman antigen

Conformational energy calculations at the PCILO level of approximation were performed on β(1 → 3) linked disaccharide consisting of N-acetylgalactosamine and galactose of the Forssman antigen to examine the side group conformations and their influence on the mutual orientations of the two pyranosyl rings. Two low energy regions for the glycosidic bond conformation have been located in the grid search using classical potential functions. The PCILO energy minimizations were then carried out in each of these regions. The preferred orientations of the nonreducing pyranosyl ring relative to the reducing ring were found to be in agreement with the available x-ray results. Moreover, the orientations of groups attached to the anomeric carbons were in good accordance with the requirements of the exo-anomeric effect.     

Self-assembly of manganese phthalocyanine on Pb(111) surface: a scanning tunneling microscopy study

The self-assembled structure of submonolayer manganese phthalocyanine (MnPc) on Pb(111) surface is investigated by using low-temperature scanning tunneling microscopy (STM). A "holelike" superlattice, which is superimposed on the self-assembled nearly quadratic network, is observed. High resolution STM images reveal that there are two distinct azimuthal orientations of MnPc molecules. It is found that by taking the two different orientations the self-assembly can further be optimized energetically by maximizing intermolecular orbital overlapping. It is this intralayer energy minimization process that leads to the characteristic holelike superlattice.     

Stereochemistry of charged nitrogen-aromatic interactions and its involvement in ligand-receptor binding

Summary Recently, new evidence was found for the involvement of charged nitrogen-aromatic interactions in ligand-receptor binding. In this study we report two favourable orientations of a phenyl ring with respect to a R-N⁺(CH₃)₃ group, based on crystal structure statistics from the Cambridge Structural Database. In the first orientation, the phenyl ring is situated in between the substituents at about 4.5 Å from the nitrogen atom, and the ring is approximately oriented on the sphere around the nitrogen atom. In the second orientation, the phenyl ring is situated in the same direction as one of the N-C bonds at about 6.0 Å from the nitrogen atom, and the ring is tilted with respect to the sphere around the nitrogen atom. The same two orientations were also found in the crystal structures of three ligand-receptor complexes, which implies that these orientations probably play a major role in molecular recognition mechanisms.     

Oriented interaction between naphthalene and alkane molecules: Theoretical interpretation of spectral shifts of ππ* bands of aromatic hydrocarbons in alkane solvents

Several features of the spectral shifts of ππ^* bands for aromatic hydrocarbons dissolved in n-alkane solvents have been explained by the existence of preferred relative orientations between the aromatic hydrocarbon and the n-alkane molecules. Theoretical evaluation of the interaction energy between naphthalene and n-pentane or n-octane actually display two preferred orientations. Moreover, these orientations are identical with those proposed, on steric grounds, for explaining the adsorption of alkanes on graphitic basal planes as proposed by Groszek.     

Study on the intermolecular interaction of C60 and simulations on the orientational properties of C60 in crystals

We developed the new intermolecular interaction model of C(60) with the quantitative accuracy for the molecular orientational properties in crystals. The energy difference (DeltaE) and the activation barrier (E(barrier)) between the two stable orientations (P and H orientations) in crystals are in the values of +14.7 and +260 meV in our model, respectively; these values are in fairly good agreement with the experimental values (DeltaE approximately +11 meV, E(barrier)=+235-+290 meV in experiments). The relaxation calculation for C(60) crystals using our model revealed that there is the reversal of the stable orientations between the P and H orientations under the high H-orientation occupancy (p(H)) in crystals, when p(H)>0.83, DeltaE<0. From the molecular dynamics calculations for C(60) crystals using our model, it is found that the phase transition is induced at T(C)=200-260 K, which is consistent with the experimental value of 260 K. Immediately below T(C), we found a great variety of molecular rotational jumps involving that between the P and H orientations every about 10(-9) s due to the thermal activation. In the high temperature phase (>T(C)), all molecules rotate irregularly like in Brownian motion involving the rotational "slumber" for approximately 10(-12)-10(-11) s.     

Simulated annealing study of diblock copolymer thin films confined between two homogeneous surfaces.

Thin films of symmetric diblock copolymers confined between two parallel surfaces have been systematically investigated by means of simulated annealing on a simple cubic lattice. The study was carried out for systems with different film thicknesses and surface-polymer interactions. Very regular equilibrium morphologies of lamella are formed in almost all cases. The dependence of lamellar orientations, total energy, chain-conformation entropy, and free energy of the confined films on the film thickness and the strength of surface-polymer interactions has been studied systematically. The influence of packing frustration on morphology is observed and the mechanisms of lamellar orientations are investigated.