Rohlf Sebastian, Gruber Manuel, Flöser Benedikt M, Grunwald Jan, Jarausch Simon, Diekmann Florian, Kalläne Matthias, Jasper-Toennies Torben, Buchholz Axel, Plass Winfried, Berndt Richard, Tuczek Felix, Rossnagel Kai
Institut für Experimentelle und Angewandte Physik , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany.
Institut für Anorganische Chemie , Christian-Albrechts-Universität zu Kiel , 24098 Kiel , Germany.
J Phys Chem Lett. 2018 Apr 5;9(7):1491-1496. doi: 10.1021/acs.jpclett.8b00338. Epub 2018 Mar 9.
Understanding and controlling the spin-crossover properties of molecular complexes can be of particular interest for potential applications in molecular spintronics. Using near-edge X-ray absorption fine structure spectroscopy, we investigated these properties for a new vacuum-evaporable Fe(II) complex, namely [Fe(pypyr(CF))(phen)] (pypyr = 2-(2'-pyridyl)pyrrolide, phen = 1,10-phenanthroline). We find that the spin-transition temperature, well above room temperature for the bulk compound, is drastically lowered for molecules arranged in thin films. Furthermore, while within the experimentally accessible temperature range (2 K < T < 410 K) the bulk material shows indication of neither light-induced excited spin-state trapping nor soft X-ray-induced excited spin-state trapping, these effects are observed for molecules within thin films up to temperatures around 100 K. Thus, by arranging the molecules into thin films, a nominal low-spin complex is effectively transformed into a spin-crossover complex.
理解和控制分子配合物的自旋交叉性质对于分子自旋电子学的潜在应用可能具有特别的意义。利用近边X射线吸收精细结构光谱，我们研究了一种新型可真空蒸发的Fe(II)配合物，即[Fe(pypyr(CF))(phen)]（pypyr = 2-(2'-吡啶基)吡咯化物，phen = 1,10-菲咯啉）的这些性质。我们发现，对于块状化合物，自旋转变温度远高于室温，但对于排列在薄膜中的分子，该温度会大幅降低。此外，虽然在实验可及的温度范围（2 K < T < 410 K）内，块状材料既未显示出光诱导激发自旋态捕获的迹象，也未显示出软X射线诱导激发自旋态捕获的迹象，但在薄膜中的分子中，直至约100 K的温度范围内都观察到了这些效应。因此，通过将分子排列成薄膜，一个名义上的低自旋配合物有效地转变为一个自旋交叉配合物。
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