Spincrossover complexes with long-lived excited high spin states stabilized by changing coordination number

随着电子工业的不断小型化，分子开关和数据存储器件的设计将成为一项关键技术。自旋交叉复合物可以作为这样的装置。自旋交叉配合物可以具有两种不同的自旋态（高自旋态和低自旋态），这两种自旋态可以用具有极高量子产率的光来寻址。不幸的是，对于许多可能的应用来说，两种状态之间热激活转换的活化能太低了。在这个项目中，这个问题将通过将配位数从6（低自旋态）改变为7（高自旋态）来解决。设计从采用强NHC和聚吡啶基配体的Fe2+配合物开始，这些配体处于非常稳定的低自旋状态。通过引入同时包含第七给体的立体活性取代基，将低自旋配合物调谐为自旋交叉配合物。采用变温紫外/可见光谱法、质子核磁共振光谱法、激光闪光光解法和磁性测量法对其磁性进行了研究。这种迄今为止很少使用的N6/N7配位变化原理应该允许观察长寿命的激发态。

In line with the ongoing miniaturization in the electronic industry, the design of molecular switches and data storage devices is going to become a key technology. Spincrossover complexes are able to serve as such devices. Spincrossover complexes can have two distinct spin states (high spin state and low spin state) which are addressable with light with exceptional high quantum yields. Unfortunately, for many possible applications the activation energy for the thermally activated conversion between the two states is far too low. In this project, this problem is going to be attacked by a change in the coordination number from six (low spin state) to seven (high spin state). The design starts with Fe2+ complexes employing strong NHC and polypyridyl ligands that are found in a very stable low spin state. The low spin complexes are tuned to spincrossover complexes by introduction of a sterically active substituent that at the same time includes a seventh donor. The magnetic properties are going to be investigated by variable temperature UV/Vis spectroscopy, proton NMR spectroscopy, as well as laser flash photolysis and measurement of the magnetic properties on a SQUID. This to date only rarely used principle of N6/N7 coordination change should allow the observation of long lived excited spin states.