Five d10 3D Metal−Organic Frameworks Constructed From Aromatic Polycarboxylate Acids and Flexible Imidazole-Based Ligands

Five new metal−organic frameworks, namely, [Cd(HIDC)(bix)]n (1), [Cd2(BDC)2(mbix)H2O]n (2), [Cd(HBTEC)(H2bix)0.5]n (3), [Cd(BTEC)(H2mbix)]n (4), and [Zn(BTEC)0.5(mbix)]n (5) (H3IDC = imidazole 4,5-dicarboxylic acid, H2BDC = 1,4-benzenedicarboxylate, H4BTEC = 1,2,4,5-benzenetetracarboxylate, bix = 1,4-bis(imidazol-1-ylmethyl)-benzene, and mbix = 1,3-bis(imidazol-1-ylmethyl)-benzene), have been synthesized under hydrothermal conditions by employing mixed ligands of various carboxylic acids with bix (or mbix). Coordination polymer 1 is a 3-fold-interpenetrated diamondoid network. Particularly, in 1 there occur triple-stranded helices based on Cd ions and bix ligands when viewed along b axis. Coordination polymer 2 is a 2D infinite layer framework, which is further interconnected by hydrogen-bond interactions leading to a 3D supramolecular architecture. Both 3 and 4 feature a 3D open framework with protonated bix (or mbix) locating in the channels, and the 3D open frameworks can be rationalized as a zeolite A...