Dysprosium(III) Metal-Organic Framework Demonstrating Ratiometric Luminescent Detection of pH, Magnetism, and Proton Conduction

A multifunctional metal-organic framework, (Hdmbpy)[Dy-(H2dobdc)2(H2O)]middot3H2O(Dy-MOF,H4dobdc = 2,5-dihydroxyterephthalicacid, dmbpy = 4,4 '-dimethyl-2,2 '-bipyridine), was synthesized and structurally characterized. The metal center DyIIIis connected by four carboxyl groups to form the [Dy2(CO2)4] binuclear nodes, which are further interconnected by eight separate H2dobdc2-ligands to form a three-dimensional (3D)framework including hydrophilic triangular channels and abundant hydro-gen-bonding networks.Dy-MOFhas good stability in aqueous solution aswell as in harsh acidic or alkaline solutions (pH range: 2.0-12.0).Furthermore, the luminescence signal ofDy-MOFundergoes a visualizedcolor change as the acidity of the solution alters, which is the typical behaviorof pH ratiometric probe. At a 100% relative humidity,Dy-MOFexhibits ahigh proton conductivity Sigma(1.70x10-4Scm-1at 303 K; 1.20x10-3Scm-1at 343 K) based on the proton hopping mechanism, which can be classified as a superionic conductor with Sigma exceeding 10-4Scm-1.Additionally, the ferromagnetic interaction and magnetic relaxation behavior are simultaneously achieved inDy-MOF. Herein, the combination of luminescence sensing, magnetism, and proton conduction in a single-phase 3D MOF may offer great potential applications in smart multitasking devices