Two new luminescent ternary Cd(II)-MOFs by regulation of aromatic dicarboxylate ligands used as efficient dual-responsive sensors for toxic metal ions in water

Abstract

Two new Cd(II) metal–organic frameworks (MOFs) formulated as [Cd(L)(atpa)]n (1) and [Cd(L)(tbta)(H2O)]n (2) [H2atpa = 2-aminoterephthalic acid, H2tbta = tetrabromoterephthalic acid, L = 1,4-bis(benzimidazol-1-yl)-2-butene] were hydrothermally synthesized. 1–2 were characterized by IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. 1 displays a 3D framework with five-fold interpenetrating dia topology. 2 holds a 2D corrugated sql layer. Both MOFs were confirmed to be dual-responsive luminescent sensors (Cu2+ and Cr2O72− for 1, Hg2+ and Cr2O72− for 2) in water through the luminescence quenching experiments. The detection limits for these species were 1.2 μM (Cu2+) and 0.29 μM (Cr2O72−) of 1, 0.043 μM (Hg2+) and 0.13 μM (Cr2O72−) of 2, respectively. The luminescence quenching mechanism was investigated.