Solvent‐Controlled Phase Transition of a Co II ‐Organic Framework: From Achiral to Chiral and Two to Three Dimensions

作者：Xing‐Po Wang, Wenmiao Chen, Hao Qi, Xiaoyi Li, Cyril Rajnák, Zhenyu Feng, Mohamedally Kurmoo, Roman Boča, Chun‐Jiang Jia, Chen‐Ho Tung, Di Sun · 发表于：Chemistry - A European Journal · 年份：2017 · DOI：10.1002/chem.201700474 · 被引用次数：117 · 研究领域：Metal-Organic Frameworks: Synthesis and Applications、Magnetism in coordination complexes、Crystallography and molecular interactions

Abstract An unprecedented reversible dynamic transformation is reported in a metal‐organic framework involving bond formation, which is accompanied by two important structural changes; achiral to chiral and two‐ to three‐dimensions. Using two bent organic ligands (diimpym=4,6‐di(1H‐imidazol‐1‐yl)pyrimidine; H 2 npta=5‐nitroisophthalic acid) and Co II (NO 3 ) 2 ⋅ 6 H 2 O the coordination polymer Co(diimpym)(npta) ⋅ CH 3 OH, ( 1⋅CH 3 OH ), was obtained solvothermally. Its structure consists of knitted pairs of square layers (4 4 ‐ sql net) of five‐coordinated Co and disordered methanol, and it crystallized in the achiral Pbca space group at room temperature. It undergoes a single crystal to single crystal (SC‐SC) transformation to a 3D interpenetrated framework (α‐polonium‐type net, pcu ) of six‐coordinated Co and ordered methanol in the chiral P 2 1 2 1 2 1 space group below 220 K. Most unusual is the dynamic temperature‐dependent shortening of a Co⋅⋅⋅O connection from a non‐bonded 2.640 Å (298 K) to a bonded 2.347 Å distance (100 K) transforming the square pyramidal cobalt polyhedron to a distorted octahedron. The desolvated crystals ( 1 ) obtained at 480 K retain the full crystallinity and crystallize in the achiral Pbca space group between 100 and 298 K but the dynamic shortening of the Co⋅⋅⋅O distance connecting the layers into the 3D pcu framework structure is observed. Following post‐synthetic insertion of ethanol ( 1⋅CH 3 CH 2 OH ) it does not exhibit the transformation...