A family of doped lanthanide metal–organic frameworks for wide-range temperature sensing and tunable white light emission

Abstract

A family of lanthanide MOFs (LnL) with high thermal and air stability have been successfully synthesized. Based on this robust framework, a series of binary and ternary co-doped LnMOFs, Eu_xTb_yL (y = 1−x) and Eu_xTb_yGd_1−x−yL, are achieved for use as ratiometric temperature sensors and white-light-emitting materials. In a binary co-doped system, Eu_0.0066Tb_0.9934L and Eu_0.0089Tb_0.9911L show good linear responses to temperature with high sensitivities over a very wide range (from 77 K to 450 K), of which Eu_0.0066Tb_0.9934L exhibits a maximum relative sensitivity (S_m) of 3.76% K⁻¹ at 450 K. This value is comparable to those of other excellent LnMOF thermometers reported recently whereas the response temperature range is greatly enlarged. The ternary mixed LnMOFs based on energy transfer of different lanthanide ions as ratiometric luminescent thermometers are firstly investigated, in which Eu_0.013Tb_0.060Gd_0.927L displays an extremely high sensitivity (S_m = 6.11% K⁻¹), representing one of the largest values reported so far in mixed LnMOFs. Furthermore, by virtue of carefully adjusting the composition of the mixed LnMOFs and the wavelength of excitation, the emission color can be systematically modulated and a tunable white light emission material, Eu_0.0062Tb_0.0087Gd_0.9851L, is successfully developed.