Entangled Coordination Frameworks with 1,4-Di(1<i>H</i>-imidazol-4-yl)benzene

Abstract

Five new entangled metal−organic frameworks {[Co(H2L)2(HCOO)2] (1), [Ni(H2L)2(HCOO)2] (2), [Co(HL)2]·2H2O (3), [Ni(H2L)2(SO4)]·2H2O (4), and [Ag2(L)] (5)} were synthesized by reactions of the corresponding metal salts with rigid ligand 1,4-di(1H-imidazol-4-yl)benzene (H2L). These compounds were characterized by single crystal X-ray structural determination, IR, thermogravimetric analysis, and powder X-ray diffraction. The isostructural behavior is observed between compounds 1 and 2. Both 1 and 2 are 3D frameworks with 3-fold inclined interpenetration of 2D (4,4) networks, where the formate anions generated from the hydrolysis of DMF molecules act as counteranions and terminal ligands. Complex 3 possesses a 6-fold interpenetrated 3D porous dia framework, while 4 is a 4-fold interpenetrated dia net decorated by the sulfate ions, which suppress the occurrence of high-fold interpenetration. In 5 each fully deprotonated ligand (L2−) coordinates with four Ag(I) atoms to form a 3-fold interpenetrated CdSO4-like framework. In addition, the stability and adsorption properties of the complexes were studied.