Institute of Chemistry and The Center for Nanoscience and Nanotechnology, Hebrew University of Jerusalem, Jerusalem, Israel.
Department of Chemistry, University of California, Berkeley, California, 94720, USA.
Chemistry. 2019 Nov 27;25(66):15067-15072. doi: 10.1002/chem.201903434. Epub 2019 Oct 15.
The formation of flexible self-assembled monolayers (SAMs) in which an external trigger modifies the geometry of surface-anchored molecules is essential for the development of functional materials with tunable properties. In this work, it is demonstrated that NO -functionalized N-heterocyclic carbene molecules (NHCs), which were anchored on Au (111) surface, change their orientation from tilted into flat-lying position following trigger-induced reduction of their nitro groups. DFT calculations identified that the energetic driving force for reorientation was the lower steric hindrance and stronger interactions between the chemically reduced NHCs and the Au surface. The trigger-induced changes in the NHCs' anchoring geometry and chemical functionality modified the work function and the hydrophobicity of the NHC-decorated Au surface, demonstrating the impact of a chemically tunable NHC-based SAM on the properties of the metal surface.
在外场刺激下改变表面锚定分子的几何形状的柔性自组装单分子层（SAMs）的形成对于开发具有可调性质的功能材料至关重要。在这项工作中，证明了在硝基基团被还原引发剂还原后，接枝在金（111）表面的 NO 功能化的 N-杂环卡宾分子（NHCs）会从倾斜取向转变为平躺取向。DFT 计算表明，重新取向的能量驱动力是化学还原的 NHCs 与 Au 表面之间较低的空间位阻和更强的相互作用。NHC 的锚固几何形状和化学功能的触发诱导变化修饰了 NHC 修饰的 Au 表面的功函数和疏水性，证明了基于化学可调 NHC 的 SAM 对金属表面性质的影响。
