A series of multifunctional lanthanide metal-organic frameworks for luminescent sensing and photocatalytic applications

Abstract

A series of isostructural lanthanide metal-organic frameworks (LnMOFs), [EuxTb1-xL(DMF)2(NO3)] (Tb-MOF for x = 0; Eu-MOF for x = 1; EuxTb1-x-MOF for x = 0.001, 0.005, 0.01, 0.05, 0.07 and 0.09, H2L =2, 2′- bipyridine-4, 4′-dicarboxylic acid) have been obtained under solvothermal conditions by adjusting the ratio of Eu3+ to Tb3+. The emission colors of the series of LnMOFs have been tuned from green to red due to the energy transfer from Tb3+ to Eu3+ ions. Furthermore, the luminescent sensing performances of the LnMOFs for hazardous phenolic compounds and pH values were studied. The results revealed that the LnMOFs can be used as luminescent sensors for selective detection β-naphthol and pH in the range of 6–1. The sensing mechanism for β-naphthol may be due to the absorption competition of the energy between the LnMOFs and β-naphthol. The different protonation levels of the uncoordinated pyridine nitrogen atom with varying pH may be the reason for the pH dependent effect. In addition, the photocatalytic activities of the LnMOFs for degradation of Rhodamine (RhB) were also studied. The results demonstrate that the LnMOFs have the efficient photocatalytic performances under UV light irradiation and show good stabilities.