Metal–organic frameworks constructed from imidazole dicarboxylates bearing aromatic substituents at the 2-position

Abstract

Seven metal–organic frameworks, [Sr(PhHIDC)(H₂O)]_n (PhH₃IDC = 2-phenyl-1H-imidazole-4,5-dicarboxylic acid) (1), {[Mn(p-OHPhHIDC)(H₂O)₂]·H₂O}_n (p-OHPhH₃IDC = 2-(p-hydroxylphenyl)-1H-imidazole-4,5-dicarboxylic acid) (2), {[Cd₂(p-OHPhHIDC)₂(phen)₂]·H₂O}_n (phen = 1,10-phenanthroline) (3), {[Cd₂(p-OHPhHIDC)₂(2,2′-bipy)₂]·H₂O}_n (2,2′-bipy = 2,2′-bipyridine) (4), [Sr(p-MePhHIDC)(H₂O)]_n (p-MePhH₃IDC = 2-(p-methylphenyl)-1H-imidazole-4,5-dicarboxylic acid) (5), [Cd₄(p-MePhHIDC)₄(py)₇(H₂O)] (py = pyridine) (6) and {[Co_1.5(p-MePhIDC)(H₂O)₃]·H₂O}_n (7) have been synthesized under hydro(solvo)thermal conditions. X-ray single-crystal analyses reveal that they have rich structural chemistry ranging from zero-dimensional (0D) tetranuclear complex (6), one-dimensional (1D) polymers (2, 3 and 4), two-dimensional (2D) polymers (1 and 5) to three-dimensional (3D) polymer (7). In these complexes, the imidazole dicarboxylate ligands show strong coordination ability and various coordination modes, which are consistent with the theoretical prediction of the substituent (phenyl, p-hydroxylphenyl or p-methylphenyl groups) effect of PhH₃IDC, p-HOPhH₃IDC or p-MePhH₃IDC ligands, respectively. The thermal properties and photoluminescence properties of compounds 1–7 have been investigated as well.