Interfaces of Ionic Liquid Systems

离子液体（IL）是熔点低于100°C的熔融盐。它们的结构多样性导致几乎无限的可能性，联合收割机结合阳离子和阴离子具有不同的性质。这允许在广泛范围内定制其物理化学性质并使其适应特定应用。在最初关注IL的本体性质之后，IL与其环境的界面的重要性也被认识到用于大量应用领域，特别是还用于催化中的新概念。由于其低蒸气压，离子液体可以通过基于真空的方法进行研究，离子液体表面科学领域在过去几年中已经开始建立。申请人小组对这一发展做出了重大贡献，特别是使用角分辨X射线光电子能谱。然而，虽然目前的研究载有关于特定系统的具体特性的信息，但仍然缺乏关于基本机制和驱动力的一般情况。由于缺乏对控制离子液体/气体（真空）和离子液体/固体界面的性质的过程和机制以及离子液体多相系统中的过程的基本理解，因此确定了该项目的阶段：将研究四个具体主题：1）表面组成、取向和富集效应的温度依赖性：地址在IL表面的分子取向，二元IL混合物的表面组成，以及大量的液-液相变对表面取向的影响。这些效应的温度依赖性对于许多应用是至关重要的，但到目前为止，在表面相关的研究中大多被忽视。2)金属络合物的溶解：旨在发展一般概念，以克服许多金属络合物在离子液体中的低溶解度，并控制这些络合物的表面活性。我们将应用具有IL-型结构的配体，并研究含金属配合物的IL。3)离子液体/支持物相互作用：涉及离子液体与固体支持物或与第二离子液体表面的界面，利用通过现有和新的原位技术从气相沉积的超薄离子液体膜。4)离子液体体系中化学反应的监测：利用X射线光电子能谱进行原位监测。我们将讨论离子液体之间的反应，离子液体中游离碱卟啉的金属化，以及离子液体中气体小分子的吸附和反应以及溶解的金属络合物。

Ionic liquids (ILs) are molten salts with a melting point below 100°C. Their structural diversity results into nearly unlimited possibilities to combine cations and anions with different properties. This allows tailoring their physico-chemical properties over a wide range and adapting them to specific applications. After an initial focus on the bulk properties of ILs, the importance of the interface of an IL with its environment has also been recognized for a large number of application areas, in particular also for new concepts in catalysis. Due to their low vapour pressure, ILs can be investigated by ultrahigh vacuum-based methods and the area of Ionic Liquid Surface Science has started to establish itself within the last years. The applicants group has significantly contributed to this development, in particular using angle-resolved X-ray photoelectron spectroscopy. However, while the presently available studies contain information on the specific properties of particular systems, a general picture of the underlying mechanisms and driving forces is still missing. This lack of fundamental understanding of processes and mechanisms governing the properties of IL/gas (vacuum) and IL/solid interfaces, and of processes in IL multiphase systems define the stage for this project: Four specific topics will be investigated: 1) Temperature-dependence of surface composition, orientation and enrichment effects: addresses molecular orientation at IL surfaces, surface composition of binary IL mixtures, and the influence of bulk liquid-liquid phase transitions on surface orientation. The temperature dependences of these effects are of pivotal importance for many applications, but up to now have been mostly ignored in surface-related studies. 2) Dissolution of metal complexes: aims at developing general concepts to overcome the low solubility of many metal complexes in ILs and to control surface activity of these complexes. We will apply complex ligands with IL-type moieties and study metal-complex-containing ILs. 3) Ionic liquid/support interactions: concern the interfaces of ILs with solid supports or with the surface of a second IL, making use of ultra-thin IL films deposited by established and new in situ techniques from the gas phase. 4) Monitoring of chemical reactions in ionic liquid-based systems: exploits the potential of X-ray photoelectron spectroscopy for in situ monitoring. We will address reactions between ILs, the metalation of free base porphyrins in ILs, and adsorption and reaction of small gaseous molecules in ILs and at dissolved metal complexes.