Electron transfer in Cobalt complexes using rigid ferrocenyl decorated polypyridyl based ligands

电子转移过程是许多化学反应中的重要步骤。这些过程在非常不同的时间尺度上进行。在该项目中，将合成杂茂络合物，氧化后，将发现从钴（II/III）离子到二茂铁基取代基的分子内电子转移。选择在钴离子周围使用的六齿配体，使得：一方面形成稳定的钴（II）络合物，对于钴（III）络合物的氧化具有高活化势垒，另一方面自由反应能低。由于这些性质，钴配合物可以在两个亚稳态中缓慢地相互转化。钴配合物配体球内的大的结构变化稳定了这两个状态，使它们在相当高的温度下可以同时观察到。这两个状态都可以通过外部刺激（如温度变化或光照射）来寻址，使这些分子在数据存储和分子开关方面的应用变得有趣。最令人感兴趣的是可能发生MMCT吸收（金属到金属电荷转移）伴随CTIST（电荷转移诱导自旋跃迁），其允许通过光照射诱导电子转移。电子转移过程将通过电化学、核和电子自旋共振光谱以及UV/维斯/NIR光谱进行详细研究。

Electron transfer processes are important steps in many chemical reactions. These processes proceed on very different time scales. Within this project hetero bimetallic complexes will be synthesized, after oxidation an intramolecular electron transfer will be found from a cobalt(II/III) ion to a ferrocenyl substituent. The employed hexadendate ligand around the cobalt ion is chosen that: on the one hand stable cobalt(II) complexes are formed, with high activation barrier for the oxidation to the cobalt(III) complex and on the other side the free reaction energy is low. Due to these properties the complex can be found in two metastable states that interconvert slowly.The large structural changes within the ligand sphere of the cobalt complexes stabilize the two states making them observable side by side at comparable high temperatures.Both states might be addressable by external stimuli like temperature change or light irradiation, making these molecules interesting for applications in data storage and molecular switches. Of high interest is the possible occurrence of an MMCT absorption (Metal to Metal Charges Transfer) accompanied with CTIST (Charge Transfer Induced Spin Transition) which allows inducing an electron transfer by irradiation of light.The electron transfer process will be studied in detail by means of electro chemical, nuclear and electron spin resonance spectroscopy as well as UV/Vis/NIR spectroscopy.