Crystalline metal phosphates with layered structures: Synthesis, luminescence, and proton conduction

Two new metal phosphates , namely, Zn(HPO 4 )(mmim) (SCU-21) and 2-Hmim·In(HPO 4 ) 2 (H 2 O) 2 (SCU-22), where mmim ​= ​1,2-dimethylimidazole and 2-Hmim ​= ​2-methylimidazolium, are synthesized and their properties are evaluated. The SCU-21 and SCU-22 compounds have layered structures with fes and sql nets, respectively. SCU-21 shows a strong blue emission under the excitation at 365 ​nm. SCU-22 shows a proton conductivity of 1.56 ​× ​10 −5  ​S ​cm −1 at 85 ​°C under 95% relative humidity.