Metal–organic frameworks with 1,4-di(1H-imidazol-4-yl)benzene and varied carboxylate ligands for selectively sensing Fe(iii) ions and ketone molecules

Abstract

Four new metal–organic frameworks (MOFs) [Zn(L)(bpdc)]·1.6H₂O (1), [Co(L)(bpdc)]·H₂O (2), [Ni₃(L)₂(bptc)₂(H₂O)₁₀]·2H₂O (3) and [Cd₂(L)(Hbptc)₂] (4) were achieved by reactions of the corresponding metal salt with mixed organic ligands of 1,4-di(1H-imidazol-4-yl)benzene (L) and 4,4′-benzophenonedicarboxylic acid (H₂bpdc) or biphenyl-2,4′,5-tricarboxylic acid (H₃bptc). They exhibit varied structures: MOFs 1 and 4 are porous three-dimensional (3D) frameworks, while 2 is an infinite one-dimensional (1D) chain and 3 is a two-dimensional (2D) network. Remarkably, 1 and 4 can act as potential fluorescent materials for sensing Fe(III) ions and different ketone molecules with high selectivity and sensitivity. In addition, MOF 1 shows selective adsorption of CO₂ over N₂.