Dual-Function Mixed-Lanthanide Metal-Organic Framework for Ratiometric Water Detection in Bioethanol and Temperature Sensing

In order to accurately and conveniently measure temperature and water content in bioethanol, a dual-function ratiometric luminescence sensor has been fabricated successfully based on mixed lanthanide metal-organic frameworks (MOFs) Eu0.02Dy0.18-MOF. In this MOF, the two lanthanides and ligand (H4L) form three luminescence centers, and they have different sensitivity toward water and temperature. Using the ratio of luminescence intensity at 416 and 614 nm, the MOF could quantitatively determine the concentration of water in dry ethanol and in bioethanol with recoveries of 91%-107%, and a detection limit of 0.1%, which is much lower than that in hydrated ethyl alcohol fuel (AEHC), 0.8% in China, 1.0% in the United States, and 4.9% in Brazil. Using the luminescence intensity ratio of Eu3+5D0 -> F-7(2) (614 nm) transition to Dy3+4F9/2 -> H-6(13/2) (573 nm) transition, the MOF could also sense temperature in range of 293 to 373 K, and 150 to 290 K with high accuracy, excellent linear relationship, reversibility, and recyclability.