Lanthanide-based complexes as efficient physiological temperature sensors

A new molecular thermometric sensor based on the terbium(III) complex [C2mim][Tb(fod)4] (C2mim – 1-methyl-3-ethylimidazolium, fod? - tetrakis-6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate), doped with 0.015% of its europium(III) analogue (1, [C2mim][Tb(fod)4]0.99985:[C2mim][Eu(fod)4]0.00015), was prepared and thermochromic behaviour evaluated from ambient temperature up to 75 °C, including in physiological range (35–45 °C). It found that intensity ratio 5D4?7F5 (TbIII) 5D0?7F2 (EuIII) transitions is correlated having three different linear regimes. Visual colorimetry allowed evaluation ranges green at temperature, yellow finally red higher temperatures. The TbIII emission extremely sensitive small variations, particularly between 25 35 were it reaches only 40% initial intensity. Confinement dopped tetrakis-complex organic polymeric matrix poly(methylmethacrylate) (PMMA) induced thermal stability 1, together a strong dependence most intense emissive transition complexes. photoluminescence quantum yield polymer-lanthanide hybrid materials increased significantly compared 1. Under 366 nm irradiation, material presents colour °C evolves 30 white tone °C.