Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Tennessee 37831, USA.
ACS Nano. 2012 Jan 24;6(1):566-72. doi: 10.1021/nn203952e. Epub 2011 Dec 22.
Supramolecular self-assembly on well-defined surfaces provides access to a multitude of nanoscale architectures, including clusters of distinct symmetry and size. The driving forces underlying supramolecular structures generally involve both graphoepitaxy and weak directional nonconvalent interactions. Here we show that functionalizing a benzene molecule with an ethyne group introduces attractive interactions in a 2D geometry, which would otherwise be dominated by intermolecular repulsion. Furthermore, the attractive interactions enable supramolecular self-assembly, wherein a subtle balance between very weak CH/π bonding and molecule-surface interactions produces a well-defined "magic" dimension and chirality of supramolecular clusters. The nature of the process is corroborated by extensive scanning tunneling microscopy/spectroscopy (STM/S) measurements and ab initio calculations, which emphasize the cooperative, multicenter characters of the CH/π interaction. This work points out new possibilities for chemical functionalization of π-conjugated hydrocarbon molecules that may allow for the rational design of supramolecular clusters with a desired shape and size.
在明确的表面上进行超分子自组装为获得多种纳米结构提供了途径，包括具有不同对称性和尺寸的团簇。超分子结构的驱动力通常涉及图形外延和弱的非共价定向相互作用。在这里，我们表明，在苯分子上用乙炔基官能化会在二维几何形状中引入吸引力相互作用，否则这将主要由分子间排斥力主导。此外，吸引力相互作用使超分子自组装成为可能，其中非常弱的 CH/π 键合和分子-表面相互作用之间的微妙平衡产生了超分子团簇的明确的“神奇”维度和手性。该过程的性质得到了广泛的扫描隧道显微镜/光谱（STM/S）测量和从头算计算的证实，这强调了 CH/π 相互作用的协作、多中心特征。这项工作为π共轭碳氢化合物分子的化学官能化指出了新的可能性，这可能允许对具有所需形状和尺寸的超分子团簇进行合理设计。
