Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR, UK.
Chem Commun (Camb). 2018 Aug 23;54(69):9651-9654. doi: 10.1039/c8cc04172e.
We study the structural and thermomechanical effects of cation substitution in the compositional family of metal-organic frameworks Zn1-xCdx(mIm)2 (HmIm = 2-methylimidazole). We find complete miscibility for all compositions x, with evidence of inhomogeneous distributions of Cd and Zn that in turn affect framework aperture characteristics. Using variable-temperature X-ray powder diffraction measurements, we show that Cd substitution drives a threefold reduction in the magnitude of thermal expansion behaviour. We interpret this effect in terms of an increased density of negative thermal expansion modes in the more flexible Cd-rich frameworks.
我们研究了金属-有机骨架 Zn1-xCdx(mIm)2（HmIm = 2-甲基咪唑）组成族中阳离子取代的结构和热机械效应。我们发现所有组成 x 都完全混溶，有 Cd 和 Zn 不均匀分布的证据，这反过来又影响了骨架孔径特征。使用变温 X 射线粉末衍射测量，我们表明 Cd 取代导致热膨胀行为幅度降低了三倍。我们根据富 Cd 骨架中负热膨胀模式的密度增加来解释这种效应。
