Facile synthesis of a water stable 3D Eu-MOF showing high proton conductivity and its application as a sensitive luminescent sensor for Cu2+ ions

Abstract

The development of cost-effective proton-conducting materials with high conductivity and water stability is currently of great interest in fuel-cell technology. By using a simple aqueous solution method, a water stable 3D Eu-MOF material, [Me₂NH₂][Eu(ox)₂(H₂O)]·3H₂O (1), can be easily synthesized from oxalic acid (H₂ox) and Eu(NO₃)₃·6H₂O on a large scale. 1 possesses a dia net topology and an extensive hydrogen-bonded network consisting of dimethyl ammonium and water molecules in 1D channels. 1 shows a high proton conductivity of 2.73 × 10⁻³ S cm⁻¹ at 55 °C and 95% relative humidity, and it is used as a sensitive luminescent sensor for Cu²⁺ ions in aqueous solutions.