In this study, we report the luminescence color tuning in the lanthanide metal-organic framework (LnMOF) ([La(bpdc)Cl(DMF)] (1); bpdc2- = [1,1'-biphenyl]-4,4'-dicarboxylate, DMF = N,N-dimethylformamide) by introducing dual emission properties in a La3+ MOF scaffold through doping with the blue fluorescent 2,2'-diamino-[1,1'-biphenyl]-4,4'-dicarboxylate (dabpdc2-) and the red emissive Eu3+. With a careful adjustment of the relative doping levels of the lanthanide ions and bridging ligands, the color of the luminescence was modulated, while at the same time the photophysical characteristics of the two chromophores were retained. In addition, the photophysical properties of the parent MOF (1) and its doped counterparts with various dabpdc2-/bpdc2- and Eu3+/La3+ ratios and the photoinduced energy transfer pathways that are possible within these materials are discussed. Finally, the temperature dependence study on the emission profile of a doped analogue containing 10% dabpdc2- and 2.5% Eu3+ (7) is presented, highlighting the potential of this family of materials to behave as temperature sensors.
Keywords: color tuning; doping; lanthanides; luminescence; metal-organic frameworks; temperature sensors.