Luminescent Mixed-Crystal Ln-MOF Thin Film for the Recognition and Detection of Pharmaceuticals

Abstract

The development of simple and reliable methods for recognition and detection of pharmaceuticals has been a matter of great concern. In this work, a series of mixed-crystal lanthanide metal-organic frameworks (Ln-MOFs) were synthesized by solvothermal method. Among them, MLMOF-3 was selected and fabricated to form nanoscale crystals and prepare luminescent Ln-MOF thin film. The different changes of emission intensity ratio of ^5D_0 → ^7F_2 (Eu^(3+), 619 nm) to ^5D_4 → ^7F_5 (Tb^(3+), 547 nm) transitions depending on the guest molecules enabled MLMOF-3 film to recognize different pharmaceutical molecules. Moreover, the intensity ratio was observed to linearly correlate to the concentration of pharmaceuticals. Compared to the traditional absolute emission intensity method based on single lanthanide ions, mixed-crystal Ln-MOF thin film generated more stable and accurate luminescent signals, which is an excellent candidate of self-referencing and self-calibrating luminescent sensor for various applications.

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