扫描探针显微技术与单分子化学和物理

在中美双方科学家的共同推动下，首届中美科学前沿研讨会于１９９８年８月２８—３０日在美国加州Ｉｒｖｉｎｅ市举行。参加会议的有中美双方科学家４０名，都是活跃在各自研究领域前沿的青年学者。会议围绕８个前沿领域开展了讨论，包括厄尔尼诺现象、生物信息识别、宇宙...     

DNA分子结构的多态性研究(Ⅲ)——生物大分子探针吖啶橙诱导λ┐DNA由线型向环型的转变

病毒和细胞体内的ＤＮＡ是以高度紧密的凝聚态存在的．自从在体外发现亚精胺、精胺可诱导无规卷曲的ＤＮＡ形成有序、独特的凝聚结构形态以来，许多学者深入研究了多价阳离子的诱导特性，以期阐明ＤＮＡ在病毒内的组装和染色体中凝聚作用的机制［１，２］．由于多价阳离子...     

硫醇在Au(111)上SA单分子层膜研究

采用自组装(SA)技术制备了正丁硫醇、正十二硫醇及两种硫醇等摩尔混合物的SA单分子层膜。用椭圆偏振仪、接触角测量仪、扫描电子显微镜(SEM)、X-射线光电子能谱仪(XPS)和原子力显微镜(AFM)对3种SA膜进行了分析表征。结果表明SA膜是取向有序的纳米级超薄膜,分子链长、基片表面的晶格取向和表面的洁净度等对膜有一定的影响,长链分子膜表面是疏水性的。用椭圆偏光、XPS和AFM3种方法测定3种单分子层膜的厚度分别为0.59～0.67nm,1.60～1.69nm,1.23～1.32nm。AFM图象进一步证实了混合单分子层膜是由两种不同厚度的微畴组成。     

Theoretical studies on intratriplex DNA with 5-bromocytosine

ＯｌｉｇｏｎｕｃｌｅｏｔｉｄｅｃａｎｒｅｃｏｇｎｉｚｅｔｈｅｍａｊｏｒｇｒｏｏｖｅｏｆｄｏｕｂｌｅｈｅｌｉｃａｌＤＮＡａｔｓｐｅｃｉｆｉｃｓｅｑｕｅｎｃｅｓｂｙｆｏｒｍｉｎｇＨｏｏｇｓｔｅｅｎｏｒｒｅｖｅｒｓｅＨｏｏｇｓｔｅｅｎｈｙｄｒｏｇｅｎｂｏｎｄｓｗｉｔｈｐｕｒｉｎｅｂａｓｅｓｏｆｔｈｅＷａｔｓｏｎＣｒｉｃｋｂａｓｅｐａｉｒｓ,ｒｅｓｕｌｔｉｎｇｉｎａｔｒｉｐｌｅｈｅｌｉｘ[1].Ｔｒｉｐｌｅｈｅｌｉｘｆｏｒｍｉｎｇｏｌｉｇｏｎｕｃｌｅｏｔｉｄｅｓｃａｎｂｅｕｓｅｄｔｏｓｅｌｅｃｔｉｖｅｌｙｃ…     

Direct observation of uncoated spectrin with atomic force microscope

Spectrin molecules extracted from human blood ceil membrane have been examined by atomic force microscopy (AFM) without using shadowing or staining procedures. A drop of the solution containing spectrin molecules was deposited on the freshly deaved mica substrate. After about 1 min, the residual solution was removed with a piece of filter paper. Afterwards the sample was imaged with a home-made atomic force microscope (AFM) in air in a constant force mode. The obtained AFM images revealed that the spectrin molecules prepared from the above procedures exhibit several kinds of structures as follows: (i) the compact rod-like spectrin heterodimers with a length of around 100 nm; (ii) bent or curved linear tetramers with a length of around 200 nm; (iii) somewhat curved spectrin hexamers, octomers or decamers with lengths of about 300, 400, or 500 nm; and (iv) high oligomers with a length above 1 000 nm.     

单分子导电性质的研究进展

介绍了测量单个有机分子导电性质的一些进展,包括分子的尺寸效应、官能团效应、分子与电极的接触效应等,以及分子逻辑器件的初步研究.     

双螺旋DNA在银和金电极上的现场付立叶表面增强拉曼光谱

采用Ｎｄ－ＹＡＧ激发器作激光光源的付立叶拉曼系统，研究了双螺旋ＤＮＡｄ（ＡＧ）８．ｄ（ＣＴ）８在银和金电极表面上的现场表面增强拉曼散射效应。结果发现在银电极表面上，该双螺肇ＤＮＡ出现ＳＥＲＳ信号的时间效应依赖于电极电势的大小。但是，高质量的ＳＥＲＳ谱表面无论在银或金电极表面上，该双螺旋ＤＮＡ均发生部分变性，而且还观察到该ＤＮＡ分子的ＳＥＲＳ谱随电极电势的变化而变化的现象。     

三链DNA |dA10 2DT10的近红外付立叶拉曼光谱

最近通过核磁共振、振动光谱和分子力学模拟研究表明,在溶液中三螺旋DNA的构象具有一定程度的复杂性和多样性．本文首次采用近红外付立叶拉曼光谱研究了三螺旋DNA dA10•2d10和相应的双螺旋DNA dA10•dT10在溶液中的构象．结果表明该三螺旋DNA同时存在C3’－内褶／反对称（A－型）和C2’－内褶／反对称（B－型）两种构象,而且在823cm－1处的较强谱带暗示还存在一种处于A和B构型之间的中间构型．对出现在1218cm-1和638cm-1处、归属于对糖环构象敏感的胸腺嘧啶残基的两个特征谱带进行分析,获得了除C2’－内褶构象外其它构型存在的证据．另外,双螺旋DNA的FT－Raman光谱表明该双螺旋DNA在溶液中以A－和B－两种构型共存．     

STUDIES ON THE STRUCTURE OF FORKED CONJUGATIVE SYSTEMS——THE CONFORMATION OF 3-ACETYL-8-PHENYL-3,5,7-OCTATRIENONE-2

The conformational properties of the title molecule in the isolated state have been investigated by the PCILO method and compared with those found from X-ray crystallographic determination. The results indicate that, in this type of forked conjugative series, because of steric hindrance, only one branch of the forking groups is basically coplanar with the conjugated trunk chain and plays the role of a terminal group, while the other one is not coplanar with the conjugated trunk chain and acts as an ordinary substitutent. Referring to the phenyl group, the acetyl group on the different sides of ethylenic chain exhibits the properties of a terminal group.     

N-[2-(2-吡啶)乙基]苯胺及其CoCl2配合物的晶体结构及配体的构象研究

本文制备了二氯[N-(2-吡啶乙基)苯胺]钴配合物, 并用X射线衍射法测定了配合物及配体的晶体结构。结合EHMO和DPCILO计算, 从能量角度, 跟踪配体从构象1(配体的晶态构象)变至构象2(配体在配合物中的晶态构象)的变化过程。