Miller Reece G, Narayanaswamy Suresh, Clark Simon M, Dera Przemslaw, Jameson Geoffrey B, Tallon Jeffery L, Brooker Sally
Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
Dalton Trans. 2015 Dec 28;44(48):20843-9. doi: 10.1039/c5dt03795f. Epub 2015 Oct 15.
The application of pressure on [Co(II)(dpzca)2], which at ambient pressure undergoes abrupt spin crossover (SCO) with thermal hysteresis, gives unique insights into SCO. It reversibly separates the crystallographic phase transition (I41/a↔P21/c) and associated abrupt SCO from the underlying gradual SCO, as shown by detailed room temperature (RT) X-ray crystallography and temperature dependent magnetic susceptibility studies, both under a range of 10 different pressures. The pressure effects are shown to be reversible. The crystal structure of the pressure-induced low-spin state is determined at RT at 0.42(2) and 1.78(9) GPa. At the highest pressure [1.78(9) GPa] the Co-N bond lengths are consistent with the complex being fully LS, and the conjugated terdentate ligands are significantly distorted out of plane. The abrupt SCO event can be shifted up to RT by application of a hydrostatic pressure of ∼0.4 GPa. These magnetic susceptibility (vs. temperature) and X-ray crystallography (at RT) studies, under a range of pressures, show that the SCO can be tuned over a wide range of temperature and pressure space, including RT SCO.
对[Co(II)(dpzca)₂]施加压力，该化合物在常压下会发生具有热滞现象的突然自旋交叉（SCO），这为SCO提供了独特的见解。通过详细的室温（RT）X射线晶体学和变温磁化率研究表明，在10种不同压力范围内，压力能可逆地将晶体学相变（I41/a↔P21/c）及相关的突然SCO与潜在的渐变SCO分离开来。压力效应是可逆的。在室温下于0.42(2) 和1.78(9) GPa压力下确定了压力诱导的低自旋态的晶体结构。在最高压力[1.78(9) GPa]下，Co-N键长与配合物完全处于低自旋状态一致，且共轭三齿配体明显偏离平面发生扭曲。通过施加约0.4 GPa的静水压力，突然的SCO事件可上移至室温。这些在一系列压力下的磁化率（与温度的关系）和X射线晶体学（室温下）研究表明，SCO可在很宽的温度和压力范围内进行调控，包括室温SCO。
