Atom-efficient mechanisms of electron-induced chemical synthesis: Activation of CO, N2 and CO2

具有适当选择能量（E0）的低能电子与分子相互作用，产生可引发化学反应的特定反应中间体。如果这些活性物质不解离，而是遇到第二反应物，则可以合成更大更复杂的分子。在理想的情况下，这种低能电子诱导合成是由两个较小的化学前体之间的简单键形成驱动的。这些产物在结构上定义良好，并包含前体分子的全部或大部分原子，因此潜在的反应可以被认为是原子高效的。举例来说，电子辐照在略高于电离阈值的E0条件下，乙烯（C2H4）和氨（NH3）的缩合混合物可诱导产生乙胺（CH3CHNH2）的氢胺化反应。这种反应在阳离子状态下进行，因此受到电离后产生的强库仑力的驱动，导致相邻分子之间的吸引相互作用和随后的反应。另一种制备基本完整的活性物质的方法是没有或只有少量解离的电子附着。这种过程通常发生在接近热的E0。该项目的目标是使用三种特定的小而容易获得的前体，即CO， CO2和N2作为这种电子诱导合成的基石。对这些反应的研究不仅有助于获得有关电子诱导化学机理的知识。更重要的是，这样的见解导致(i)对天体化学反应的详细理解，以及（ii）电子诱导化学的进步，以实现材料的良好控制功能化。因此，拟议项目的另一个目标是展示材料科学如何从天体化学过程的研究中获益。

Low-energy electrons with suitably selected energy (E0) interact with molecules to produce specific reactive intermediates that can initiate chemical reactions. If these reactive species do not dissociate but encounter a second reactant, synthesis of larger and more complex molecule can be the result. In the ideal case, such low-energy electron-induced synthesis is driven towards the final product by simple bond formation between the two smaller chemical precursors. These products are structurally well defined and incorporate all or most of the atoms of the precursor molecules so that the underlying reaction can be regarded as atom-efficient. As an example, electron irradiation of condensed mixtures of ethylene (C2H4) and ammonia (NH3) at E0 just above the ionization threshold induces a hydroamination reaction yielding ethylamine (CH3CHNH2). Such reactions proceed in the cation state and are thus driven by strong Coulomb forces arising after ionization and leading to attractive interactions and subsequent reaction between adjacent molecules. Another approach to prepare largely intact activated species is electron attachment without or with only minor dissociation. Such processes typically occur at near-thermal E0.The objective of this project is to use three specific small and readily available precursors, namely, CO, CO2, and N2 as building blocks for such electron-induced synthesis. The study of these reactions does not only serve to gain knowledge regarding the mechanisms of electron-induced chemistry. More importantly, such insight leads to (i) a detailed understanding of astrochemical reactions as well as (ii) to the advancement of electron-induced chemistry for a well-controlled functionalisation of materials. Another objective of the proposed project is thus to show how material science may draw advantage from the study of astrochemical processes.