Amphiphilic iron(II) spin crossover coordination polymers: crystal structures and phase transition properties
Amphiphilic iron(II) spin crossover coordination polymers: crystal structures and phase transition properties
复制标题
DOI：
10.1039/c8tc05580g
复制
发表时间：
2019-02-07
影响因子：
6.4
通讯作者：
Weber, Birgit
中科院分区：
文献类型：
--
作者：
Weihermueller, Johannes;Schlamp, Stephan;Weber, Birgit
合成了以N_2 O_2为配位基，以1，2-双（4-吡啶基）乙炔、1，2-双（4-吡啶基）乙烯或1，2-双（4-吡啶基）乙烷为桥连配体的铁（II）配位聚合物。所有的配合物显示一个相当相似的突然自旋跃迁高于室温，这是使用磁性测量和穆斯堡尔谱研究。桥连配体和烷基链长度的变化允许在338 K和357 K之间的范围内微调转变温度。两个配位聚合物和一个起始配合物的单晶X-射线结构分析揭示了在所有情况下形成的两亲性配合物的脂质层样排列。通过热重分析、差示扫描量热法、X射线粉末衍射和偏光显微镜的进一步表征显示在所有情况下的固-固相变。这些转变决定了自旋交叉行为，并取决于由配体外周中的烷基链控制的晶体堆积。因此，与所提出的系统的自旋交叉性能控制的配体结构的小的变化。关于技术应用，旋涂被证明是适合于作为薄膜的复合物的加工，并且此外，可以通过分层技术产生复合物的薄的小片。
Iron(II) coordination polymers with an N2O2 coordinating Schiff base-like equatorial ligand bearing different alkyl chain lengths (C16, C18, C20, and C22) and 1,2-bis(4-pyridyl) ethyne, 1,2-bis(4-pyridyl) ethene or 1,2-bis(4-pyridyl) ethane as bridging ligand are synthesized. All complexes display a rather similar abrupt spin transition above room temperature, which is investigated using magnetic measurements and Mo ssbauer spectroscopy. Variation of the bridging ligand and the alkyl chain lengths allows fine tuning of the transition temperature in the range between 338 K and 357 K. Single crystal X-ray structure analysis of two coordination polymers and one of the starting complexes reveals the formation of a lipid layer-like arrangement of the amphiphilic complexes in all cases. Further characterization by thermal gravimetric analysis, differential scanning calorimetry, X-ray powder diffraction, and polarized optical microscopy show in all cases solid-solid phase transitions. Those transitions determine the spin crossover behavior and depend on the crystal packing that is controlled by the alkyl chains in the outer periphery of the ligand. Thus, with the presented system the spin crossover properties are controlled by small alterations of the ligand structures. With respect to technological applications, spin coating is shown to be suitable for the processing of the complexes as thin films and furthermore thin platelets of the complexes can be generated by delamination techniques.