Vacuum-Evaporable Spin-Crossover Complexes in Direct Contact with a Solid Surface: Bismuth versus Gold

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• 作者：Sascha Ossinger ; Holger Naggert ; Lalminthang Kipgen ; Torben Jasper-Toennies ; Abhishek Rai ; Julian Rudnik ; Fabian Nickel ; Lucas M. Arruda ; Matthias Bernien ; Wolfgang Kuch ; Richard Berndt ; Felix Tuczek
• 刊名：Journal of Physical Chemistry C
• 出版年：2017
• 出版时间：January 19, 2017
• 年：2017
• 卷：121
• 期：2
• 页码：1210-1219
• 全文大小：603K
• ISSN：1932-7455

文摘

To investigate the ability for spin-state switching of spin-crossover (SCO) complexes adsorbed to solid substrates, the SCO complex [Fe(H₂B(pz)₂)₂(phenme₄)] (pz = pyrazole, phenme₄ = 3,4,7,8-tetramethyl-1,10-phenanthroline) is prepared. The new complex is investigated by magnetic susceptibility measurements and Mößbauer spectroscopy in the solid state and by temperature-dependent UV/vis spectroscopy in a thin film deposited by physical vapor deposition (PVD) on quartz glass. Thermal- and light-induced SCO is observed in the bulk and the film on glass. Submonolayers of this complex obtained by PVD are studied by temperature-dependent near-edge X-ray absorption fine structure (NEXAFS) on Au(111) as well as Bi(111) and by scanning tunneling microscopy (STM) on Au(111). NEXAFS shows thermal- and light-induced spin-state switching of the complex on Bi(111), however, with a large temperature-independent high-spin fraction (∼50%). On the other hand, combined evidence from NEXAFS and STM indicates that on Au(111) the complex dissociates into [Fe(H₂B(pz)₂)₂] and phenme₄. Similar observations are made with the parent complex [Fe(H₂B(pz)₂)₂(phen)], which on Bi(111) stays intact and exhibits thermal-induced as well as light-induced SCO, but on Au(111) dissociates into [Fe(H₂B(pz)₂)₂] and phen.