取代烷基侧链长度对二维纳米结构的影响

合成了一系列烷基取代的间苯三酚衍生物,并在大气条件下用扫描隧道显微镜研究了它们在高定向裂解石墨表面的吸附和组装行为.实验结果表明,这些自组装分子具有条状结构特征.在链长较短的分子图像中,两条平行的烷氧基链肩并肩地排列在苯环的一侧,另一条烷氧基链则排列在苯环的另一侧,链与链之间彼此相互交错排列形成均一的烷基条带.当链长增加时,这种高稳定性和密排结构遭到破坏,出现单个分子和分子对共存的组装结构.这是由于烷基链与烷基链之间以及烷基链与基底之间的作用力共同决定的.通过调控分子烷基链的长度可以得到不同的表面二维纳米结构.

Effect of Length of Substituted Alkyl Chain on 2-D Nanostructure

A series of alkyl-substituted 1,3,5-triphenols were synthesized, and their adsorption and assembling behavior on a highly oriented pyrolytic graphite(HOPG) surface were studied by scanning tunneling microscopy(STM) under ambient conditions. A characteristic stripe-like structure was observed from these samples. In high-resolution STM images of the molecules with shorter chains, we found that two parallel alkyl chains were arranged side by side on one side of the phenylring, another alkyl chain was arranged on the other side and the alkyl chains interdigitate to form a uniform alkane lamella. The high stability and close-packed assembly were interrupted with increasing the chain length, and the co-existing self-assembly structure of the single molecule and dimmer was formed. This result is attributed to Van der Waals interactions between the alkyl chain-alkyl chain and the alkyl chain-substrate. This observation illustrates that changing alkyl chain length is an effective method for obtaining various two-dimensional molecular assemblies.