Employing three-blade propeller lanthanide complexes as molecular luminescent thermometers: study of temperature sensing through a concerted experimental/theory approach

We report the synthesis, structures, magnetic and luminescence properties of a series of three-blade propeller homoleptic lanthanide complexes [LnL(3)](ClO4)(3)center dot H2O center dot 2MeCN (Ln = Eu (1), Tb (2), Dy (3), Er (4), Yb (5), Gd (6); L = 2,6-bis(1-methyl-imidazol-2-yl)pyridine). The Eu, Tb, and Dy analogues exhibit the characteristic lanthanide-based luminescence. Remarkably, the mixed Eu/Tb complex with a metal ratio of 1:10 can be used as a ratiometric thermometer in the solid-state between 130 and 220 K with the maximum value of S-r = 6.6% K-1 within the range of 150-170 K. Theoretical calculations allow not only modelling of the luminescence properties of pure complexes but also rationalization of the performances of the mixed Eu/Tb thermometers.

Automated summary

The synthesis, structures, magnetic and luminescence properties of a series of three-blade propeller homoleptic lanthanide complexes are reported, and the mixed Eu/Tb complex is found to be a ratiometric thermometer in the solid-state.