Elucidating Energy-Transfer Dynamics Within and Beyond Lanthanide Metal-Organic Frameworks

The fundamental understanding of energy-transfer dynamics in lanthanide metal organic frameworks (Ln-MOFs) is essential for their application as light-emitting materials. In this work, we report time-resolved spectroscopic studies on the energy-transfer (ENT) process within mixed-metal Ln-MOFs based on Tb3+ and Eu3+ (Tb/Eu-MOF) as well as the ENT process from Ln-MOFs to methylene blue (MW) that encapsulated the MOF. We show that the Tb/Eu-MOF not only exhibits an extended emission spectrum with respect to the single-metal Ln-MOF but also shows a tunable emission lifetime by altering the atomic ratio of Tb3+ and Eu3+, which can be attributed to the additional ENT pathway from Tb3+ to Eu3+. Moreover, in the presence of MB+, ENT can occur from Tb3+ but not from Eu3+ in the mixed-node Ln-MOF, which provides a viable approach to tune the ENT rate and efficiency to MB+ by altering the atomic ratio of Tb3+ and Eu3+.