A Highly Stable Yttrium Organic Framework as a Host for Optical Thermometry and D2 O Detection.

The yttrium organic framework (Y0.89 Tb0.10 Eu0.01 )6 (BDC)7 (OH)4 (H2 O)4 (BDC=benzene-1,4-dicarboxylate) is hydrothermally stable up to at least 513 K and thermally stable in air in excess of 673 K. The relative intensities of luminescence of Tb3+ and Eu3+ are governed by Tb3+ -to-Eu3+ phonon-assisted energy transfer and Tb3+ -to-ligand back transfer and are responsible for the differing temperature-dependent luminescence of the two ions. This provides a ratiometric luminescent thermometer in the 288-573 K temperature range, not previously seen for MOF materials, with a high sensitivity, 1.69±0.04 % K-1 at 523 K. In aqueous conditions, loosely bound H2 O can be replaced by D2 O in the same material, which modifies decay lifetimes to yield a quantitative luminescent D2 O sensor with a useful sensitivity for practical application.