摘要
The use of a bottom-up approach to the fabrication of nanopatterned functional surfaces, which are capable to respond to external stimuli, is of great current interest. Herein, the preparation of light-responsive, linear supramolecular metallopolymers constituted by the ideally infinite repetition of a ditopic ligand bearing an azoaryl moiety and Co(II) coordination nodes is described. The supramolecular polymerization process is followed by optical spectroscopy in dimethylformamide solution. Noteworthy, a submolecularly resolved scanning tunneling microscopy (STM) study of the in situ reversible trans-to-cis photoisomerization of a photoswitchable metallopolymer that self-assembles into 2D crystalline patterns onto a highly oriented pyrolytic graphite surface is achieved for the first time. The STM analysis of the nanopatterned surfaces is corroborated by modeling the physisorbed species onto a graphene slab before and after irradiation by means of density functional theory calculation. Significantly, switching of the monolayers consisting of supramolecular Co(II) metallopolymer bearing trans-azoaryl units to a novel pattern based on cis isomers can be triggered by UV light and reversed back to the trans conformer by using visible light, thereby restoring the trans-based supramolecular 2D packing. These findings represent a step forward toward the design and preparation of photoresponsive “smart” surfaces organized with an atomic precision.
摘要译文
使用自底向上的方法来制造能够响应外部刺激的纳米图案化功能表面，这是目前非常重要的。在这里，准备光响应，描述了由具有偶氮芳基部分和Co（II）配位节点的双位配体的理想无限重复构成的线性超分子金属聚合物。超分子聚合过程之后在二甲基甲酰胺溶液中进行光谱分析。值得注意的是，本文首次实现了将自组装成二维晶体图案的光可开关金属聚合物反转为顺式光异构化到高度取向的热解石墨表面。通过密度泛函理论计算，在照射之前和之后通过将物理吸附物质建模到石墨烯平板上来证实纳米图案化表面的STM分析。显著，具有反式 - 偶氮芳基单元的超分子Co（II）金属聚合物转化为基于顺式异构体的新型图案可以通过使用可见光反射回到反式构象器，从而恢复反式超分子2D填料。这些发现代表了向原子精度组织的光响应“智能”表面的设计和制备迈出的一步。
Mohamed El Garah[1]; Etienne Borré[1,2]; Artur Ciesielski[1]; Arezoo Dianat[3]; Rafael Gutierrez[3]; Gianaurelio Cuniberti[3,4]; Stéphane Bellemin-Laponnaz[2,*]; Matteo Mauro[1,*] and Paolo Samorì[1,*];. Light-Induced Contraction/Expansion of 1D Photoswitchable Metallopolymer Monitored at the Solid–Liquid Interface[J]. Small, 2017,13(40)