Europium complexes with dinitropyrazole: unusual luminescence thermal behavior and irreversible temperature sensing.

Europium 3,5-dinitropyrazole complexes demonstrate an unusual luminescence behavior upon heating, i.e. there is a noticeable increase of the luminescence intensity beyond a temperature of 200 °C. We propose and successfully demonstrate the possibility of using this phenomenon for sensing overheating above this temperature. An on/off ratio of 37 is reached.