Tuning of the Critical Temperature in Magnetic 2D Coordination Polymers by Mixed Crystal Formation
Tuning of the Critical Temperature in Magnetic 2D Coordination Polymers by Mixed Crystal Formation
复制标题
通过混合晶体形成调节磁性二维配位聚合物的临界温度
DOI：
10.1021/acs.cgd.8b00245
复制
发表时间：
2018
影响因子：
3.8
通讯作者：
Christian Näther
中科院分区：
文献类型：
--
作者：
Carsten Wellm;Michał Rams;Tristan Neumann;Magdalena Ceglarska;Christian Näther
Co(NCS)2和Ni(NCS)2在不同条件下与4-乙酰基吡啶反应，形成[CoxNi1-x(NCS)2(4-乙酰基吡啶)2]n(x=0.15 0.3，0.5和0.7)的层状化合物混晶。采用X射线粉末衍射(XRPD)、原子吸收光谱(AAS)、同时扫描电子显微镜(SEM)和能量色散X射线能谱(EDX)、差示扫描量热法(DSC)、磁学和热容测量相结合的方法研究了混晶的形成。根据合成方法的不同，XRPD已经表明，可以得到同相或非均相的混晶，其中当M=Co或Ni时，同金属对[M(NCS)2(4-乙酰基吡啶)2]n的物理混合模式有明显的差异。在热力学控制下，混合晶体也可以从物理混合物中获得，这表明它们比同金属化合物更稳定。这进一步得到了原子吸收光谱的支持，表明混晶的溶解度比同金属化合物的溶解度低。磁测量和热容测量表明，磁性有序的临界温度随着Ni含量的增加而线性增加，也证实了得到了均匀的样品。
Reaction of Co(NCS)2and Ni(NCS)2with 4-acetylpyridine under different conditions leads to the formation of mixed crystals of the layered compound with the composition [CoxNi1–x(NCS)2(4-acetylpyridine)2]n(x= 0.15 0.3, 0.5, and 0.7). Mixed crystal formation was investigated by a combination of X-ray powder diffraction (XRPD), atomic absorption spectroscopy (AAS), simultaneous scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), differential scanning calorimetry (DSC), and magnetic and heat capacity measurements. Dependent on the synthetic method, homo- or heterogeneous mixed crystals were obtained as already indicated by XRPD, where significant differences to the pattern of physical mixtures of the homometallic counterparts [M(NCS)2(4-acetylpyridine)2]nwith M = Co or Ni) with the same Co/Ni ratio are observed. Mixed crystals can also be obtained from physical mixtures under thermodynamic control, indicating that they are more stable than the homometallic compounds. This is further supported by AAS, which indicates that the solubility of the mixed crystals is lower than that of the homometallic compounds. Magnetic and heat capacity measurements show a linear increase of the critical temperature of magnetic ordering with increasing Ni content and also confirm that homogeneous samples were obtained.