Luminescent metal–organic frameworks with a 2-(4-pyridyl)-terephthalic acid ligand for detection of acetone

Abstract

Three metal–organic frameworks (MOFs), [Zn(pta)(H₂O)]_n (1) {[Zn(pta)]·H₂O}_n (2) and {[Cd(pta)]·H₂O)}_n (3) [H₂pta = 2-(4-pyridyl)-terephthalic acid], were isolated by hydrothermal synthesis. Single-crystal X-ray analysis reveals that compound 1 shows a 2D layer-like network, while compounds 2 and 3 feature different 3D frameworks with Schläfli symbols of {4^2.6.8^3} and {4^6.6^4} respectively, in which the deprotonated pta²⁻ ligands are indicative of diverse coordination modes. The thermostability, water stability and luminescent properties of 1–3 were investigated in the solid state at room temperature. It is noteworthy that 3 shows high selectivity for the detection of acetone in different solvents via a fluorescence quenching mechanism. By virtue of its excellent detection efficiency, applicability in water and reusability, compound 3 can be a promising fluorescent material for practical acetone sensing.