Zhou Hao-Long, Zhang Jie-Peng, Chen Xiao-Ming
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University, Guangzhou, China.
Department of Chemistry and Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou, China.
Front Chem. 2018 Jul 24;6:306. doi: 10.3389/fchem.2018.00306. eCollection 2018.
Solvothermal reactions of 3-(4-pyridyl)-benzoic acid (Hpba) with a series of transition metal ions yielded isostructral metal-organic frameworks [M(pba)]·2DMA (MCF-52; M = Ni, Co, Zn, Cd, or mixed Zn/Cd; DMA = ,-dimethylacetamide) possessing two-dimensional fence-like coordination networks based on mononuclear 4-connected metal nodes and 2-connected organic ligands. Variable-temperature single-crystal X-ray diffraction studies of these materials revealed huge positive and negative thermal expansions with |α| > 150 × 10 K, in which the larger metal ions give the larger thermal expansion coefficients, because the increased space not only enhance the ligand vibrational motion and hinged-fence effect, but also allow larger changes of steric hindrance between the layers. In addition, the solid-solution crystal with mixed metal ions further validates the abundant thermal expansion mechanisms of these metal-organic layers.
3-(4-吡啶基)苯甲酸（Hpba）与一系列过渡金属离子的溶剂热反应生成了同构的金属有机骨架[M(pba)]·2DMA（MCF-52；M = Ni、Co、Zn、Cd或混合的Zn/Cd；DMA = N,N-二甲基乙酰胺），其具有基于单核4连接金属节点和2连接有机配体的二维栅栏状配位网络。对这些材料进行的变温单晶X射线衍射研究表明，它们具有巨大的正热膨胀和负热膨胀，|α| > 150×10⁻⁶ K⁻¹，其中较大的金属离子具有较大的热膨胀系数，这是因为增加的空间不仅增强了配体的振动运动和铰链栅栏效应，还允许层间空间位阻发生更大的变化。此外，具有混合金属离子的固溶体晶体进一步验证了这些金属有机层丰富的热膨胀机制。
