Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy Aarhus University, 8000 Aarhus, Denmark.
ACS Nano. 2010 Jul 27;4(7):4097-109. doi: 10.1021/nn100450q.
Supramolecular self-assembly on surfaces, guided by hydrogen bonding interactions, has been widely studied, most often involving planar compounds confined directly onto surfaces in a planar two-dimensional (2-D) geometry and equipped with structurally rigid chemical functionalities to direct the self-assembly. In contrast, so-called molecular Landers are a class of compounds that exhibit a pronounced three-dimensional (3-D) structure once adsorbed on surfaces, arising from a molecular backboard equipped with bulky groups which act as spacer legs. Here we demonstrate the first examples of extended, hydrogen-bonded surface architectures formed from molecular Landers. Using high-resolution scanning tunnelling microscopy (STM) under well controlled ultrahigh vacuum conditions we characterize both one-dimensional (1-D) chains as well as five distinct long-range ordered 2-D supramolecular networks formed on a Au(111) surface from a specially designed Lander molecule equipped with dual diamino-triazine (DAT) functional moieties, enabling complementary NH...N hydrogen bonding. Most interestingly, comparison of experimental results to STM image calculations and molecular mechanics structural modeling demonstrates that the observed molecular Lander-DAT structures can be rationalized through characteristic intermolecular hydrogen bonding coupling motifs which would not have been possible in purely planar 2-D surface assembly because they involve pronounced 3-D optimization of the bonding configurations. The described 1-D and 2-D patterns of Lander-DAT molecules may potentially be used as extended molecular molds for the nucleation and growth of complex metallic nanostructures.
表面上的超分子自组装，受氢键相互作用的引导，已得到广泛研究，这些研究通常涉及直接在表面上以平面二维（2-D）几何形状限制的平面化合物，并配备结构刚性的化学官能团来指导自组装。相比之下，所谓的分子登陆器是一类化合物，一旦吸附在表面上，就会呈现出明显的三维（3-D）结构，这是由于分子背板配备了庞大的基团，作为间隔腿。在这里，我们展示了由分子登陆器形成的扩展氢键表面结构的第一个例子。在受控的超高真空条件下使用高分辨率扫描隧道显微镜（STM），我们对一维（1-D）链以及在 Au（111）表面上由专门设计的带有双氨基三嗪（DAT）官能团的登陆器分子形成的五个不同的长程有序 2-D 超分子网络进行了表征，从而实现互补的 NH...N 氢键。最有趣的是，将实验结果与 STM 图像计算和分子力学结构建模进行比较表明，观察到的分子登陆器-DAT 结构可以通过特征的分子间氢键偶联模式来合理化，这些模式在纯平面 2-D 表面组装中是不可能的，因为它们涉及到键合构型的明显 3-D 优化。描述的分子登陆器-DAT 分子的 1-D 和 2-D 图案可能潜在地用作复杂金属纳米结构成核和生长的扩展分子模具。
