Polyoxotungstate Functionalization in the Context of Molecular Spintronics

基于分子的自旋电子学的发展，即利用与分子电荷和自旋态相关的电荷输运现象，需要特殊的分子材料来允许多种多样的磁性官能化和可重复的电接触模式。在这种背景下，高核度结构类型的多氧钨酸盐尤其有希望，因为它们表现出高的热稳定性，大量基于W(VI)/W(V)的氧化还原过程几乎没有结构变化，以及多齿配体功能，使得复杂的基于异金属的自旋结构能够集成到多氧钨酸盐支架中。本项目的中心是开发新的合成策略，用于磁性多氧钨酸盐的(后)官能化，最终目标是允许此类分子的精确电接触，例如在双结扫描隧道显微镜实验中。这将首次使系统地研究这类系统的自旋电子学特性成为可能。该项目强调使用有机膦酸盐，特别是有机砷酸盐，最近显示出在实现和控制关键方面的特别前景，从电荷和溶解性、溶液稳定性、在金属衬底上的化学吸附和有序单分子膜的形成，到新的异金属亚结构的整合和以前未知的团簇结构的演变。在这里，使用有机芳酸酯可以绕过与其他已经建立的有机官能化技术相关的某些限制。此外，除了目标自旋电子学材料的性质外，我们的初步结果还表明，迄今为止几乎未知的多氧钨酸盐的RAsO_3官能化具有巨大的潜力，可以显著扩展其结构化学，具有实现前所未有的团簇类型的前景。

The development of molecule-based spintronics, i.e. the exploitation of charge transport phenomena associated with the correlated molecular charge and spin states, requires particular molecular materials that allow for a versatile magnetic functionalization and reproducible electric contact modes. High-nuclearity structure types of polyoxotungstates are especially promising in this context, as they exhibit high thermal stability, a multitude of W(VI)/W(V)-based redox processes with virtually no structural changes, and multidentate ligand functionality that enables the integration of complex heterometal-based spin structures into the polyoxotungstate scaffolds.This project centers on the development of novel synthesis strategies for the (post-) functionalization of magnetic polyoxotungstates with the eventual aim to allow precise electrical contacts to such molecules, e.g. in two-junction scanning tunneling microscopy experiments. This would, for the first time, enable a systematic investigation of the spintronics characteristics of such systems. The project emphasizes the use of organophosphonates and especially organoarsonates, which recently have shown particular promise for achieving and controlling key aspects ranging from charge and solubility, stability in solution, chemisorption onto metal substrates and formation of ordered monolayers, to the integration of novel heterometal substructures and evolution of previously unknown cluster architectures. Here, the use of organoarsonates can circumvent certain limitations pertinent to other, already established organic functionalization techniques. Furthermore, next to the targeted spintronics materials properties, our preliminary results also point to a great potential of the hitherto nearly unknown RAsO3 functionalization of polyoxotungstates as a general pathway to significantly expand their structural chemistry, with the prospect of realizing unprecedented cluster types.