Mimicking the active centres in iron-sulfur proteins: reaction kinetic study of the catalytic behavior and and the redox activity of free FexSy-clusters in an ion trap

小的铁硫（FeS-）簇通常被认为是最常见的天然蛋白质（FeS-蛋白质）的活性中心，因此对所有生物体都具有根本的重要性。除了在生物化学氧化还原反应中作为电子传递介质的功能外，FeS-团簇在许多关键过程中作为生物催化剂特别重要。特别是，温和的反应条件和这种生物催化剂活化空气组分的能力使它们成为“绿色”即环境友好和可持续催化的理想材料。因此，研究酶反应中的催化机制不仅对基本了解生命的功能性特别重要;酶作为生物催化剂，更代表了从自然界学习并在工业上利用这一知识开发新的催化活性和选择性材料的理想系统。然而，对这些过程的详细了解受到FeS蛋白质非常复杂的结构及其有机环境的影响的极大阻碍。为了详细了解分子水平上的基本过程，必须分离蛋白质的活性中心，并研究其与环境无关的内在性质。在这种情况下，我们将模拟活性中心的FeS-蛋白质的气相簇的形式，并将研究其氧化还原活性和催化性能在不同的模型反应中的离子阱实验。该实验方法的目的是阐明基元反应步骤及其动力学，并在严格的分子水平上理解键活化和键形成过程以及相应的电荷转移过程的基本机制，特别强调对燃料活化反应性的研究（用于燃料电池）、析氢、氨合成以及脂肪族和芳香族烃的有效和选择性氧化。对于这些系统，我们将进行反应动力学，反应动力学和结构测定实验作为集群大小的函数，和集群组成，以确定最活跃的集群。通过改变团簇的电荷状态以及用Mo、V或Ni原子取代Fe原子将实现团簇性质的进一步优化。

Small iron-sulfur (FeS-)clusters are often considered as the active centers of the most commonly naturally occurring proteins (FeS-proteins) and are thus of fundamental importance for all living organisms. Besides their function as electron transfer medium in biochemical redox reactions, FeS-clusters are especially important as biocatalysts in numerous pivotal processes. In particular, the mild reaction conditions and the ability of such biocatalysts to activate components of the air makes them ideal materials for a "green" i.e. environmentally friendly and sustainable catalysis. Thus, the investigation of the catalytic mechanisms in enzyme reactions is not only of particular importance for a basic understanding of the functionality of life; enzymes as biocatalysts rather represent ideal systems to learn from nature and to use this knowledge industrially for the development of new catalytically active and selective materials. The detailed understanding of the processes is, however, considerably hampered by the very complex structure of FeS-proteins and the influence of their organic environment. For a detailed understanding of the elementary processes on a molecular level it is mandatory to isolate the active centers of the proteins and to study their intrinsic properties independent of their environment. In this context, we will mimic the active centers of FeS-proteins in form of gasphase clusters and will study their redox activity and catalytic properties in different model reactions in an ion trap experiment. The aim of this experimental approach is the elucidation of elementary reaction steps and their dynamics as well as the understanding of basic mechanisms involved in bond activation and bond formation processes and the corresponding charge transfer processes on a strictly molecular level.Particular emphasis will be on the investigation of the reactivity with respect to the activation of fuels (for application in fuel cells), the hydrogen evolution, the ammonia synthesis as well as the effective and selective oxidation of aliphatic and aromatic hydrocarbons. For these systems we will perform reaction kinetic, reaction dynamic and structure determination experiments as a function of cluster size, and cluster composition to identify the most active clusters. Further optimization of the cluster properties will be achieved by changing the charge state of the clusters as well as by substitution of Fe atoms with Mo, V, or Ni atoms.