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 ](ClO 4 ) 3 H 2 O2MeCN (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 150170 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. The synthesis, structures, magnetic and luminescence (including thermometry) properties of a series of three-blade propeller homoleptic lanthanide complexes are reported.