Three metal-organic frameworks constructed from 3,3′,5,5′-azobenzene-tetracarboxylic acid: Synthesis, structure and luminescent sensing

Abstract

Three new metal-organic frameworks (MOFs), namely, {[Zn2(abtc)(bpa)(H2O)]·5H2O}n(1), {[Cd3(abtc)2]·2H3O}n(2) and [Cd3(H2abtc)3(bpp)(μ2-OH2)2(H2O)3]n(3) [bpa = bis(4-pyridyl)amine, bpp = 1,3-bis(4-pyridyl)propane] have been constructed mainly from the ligand of 3,3′,5,5′-azobenzene-tetracarboxylic acid (H4abtc) and metal centers of Zn2+ or Cd2+.Single crystal X-ray diffraction analysis reveals that compounds 1 and 2 display 3D frameworks, while compound 3 displays a 2D layered structure consisting of intriguing 1D rhombic chains and bpp ligands. The solid-state luminescent properties of three products are investigated at room temperature. Furthermore, fluorescence measurements indicated that the complex 1 could sensitively sense Fe3+ ions and nitrobenzene molecules.