ICMADS (In-situ Chemistry of Molecular Assemblies on Dielectric Surfaces)

最近，表面化学的概念已被用于制造功能分子结构。这种方法开辟了创造热和化学稳定结构的可能性，这些结构不能通过标准沉积和组装技术实现。此外，将反应限制在两个维度上可以实现在溶液中不可接近的新反应路线。到目前为止，已发表的涉及表面化学的实验仅限于金属表面，或者在最近的一个例子中是在NaCl/Ag（100）的单层上。在这个项目中，我们将探索在介电表面上创建分子结构的表面化学。两个根本不同的战略，表面上的化学将在两个模型表面，即氟化钙和方解石进行调查。首先，我们将探索通过金属络合作用在二元酸、三元酸或多氮杂芳族化合物与金属原子共吸附时形成的扩展结构。第二，我们将诱导通过分子如碘代芳烃的原位异裂热裂解和通过二硼酸和三硼酸与α-二醇的酯化获得的自由基的共价偶联。该项目包括定制分子的设计和合成，它们的活化和详细的表面和分子表征，通过使用变温非接触式扫描力显微镜以及紫外光电子和亚稳态冲击电子光谱直接成像。将进行模拟以深入了解分子结构并确认反应途径。

Recently, the concept of on-surface chemistry has been exploited for fabrication of functional molecular structures. This approach opens up the possibility for creating thermally and chemically stable structures that cannot be achieved by standard deposition and assembly techniques. Moreover, confining the reaction in two dimensions may enable new reaction routes that are not accessible in solution. Published experiments involving on-surface chemistry have been limited to metallic surfaces so far, or in one recent example on a monolayer of NaCl/Ag(100). In this project we will explore on-surface chemistry for creating molecular structures on dielectric surfaces. Two fundamentally different strategies for on-surface chemistry will be investigated on two model surfaces, namely calcium fluoride and calcite. First, we will explore the formation of extended structures by metal-complexation upon co-adsorption of diacids, triacids or polyazaaromatics and metal atoms. Second, we will induce covalent coupling of radicals obtained by in-situ heterolytic thermal cleavage of molecules such as iodoaromatics and by esterification of di- and triboronic acids with alpha-diiols. The project includes the design and synthesis of tailor-made molecules, their activation and a detailed surface and molecular characterisation by direct imaging using variable-temperature non-contact scanning force microscopy as well as ultraviolet photoelectron and metastable impact electron spectroscopy. Simulations will be performed for gaining insights into the molecular structures and to confirm reaction pathways.