Temperature sensitive properties and preparation of europium complexes with double ligands

Abstract Temperature sensitive paints (TSPs) are a class of rising materials for non‐contact temperature measurement technology. Efficient complexes with remarkable luminescent properties play the core role in TSPs. Rare earth organic complexes are often used as probe molecules for TSPs because of their long fluorescence lifetime, narrow fluorescence emission peaks, high fluorescence intensity, and large Stokes shift. Herein, two europium‐based complexes, Eu(PCCA) 3 phen and Eu (PMCA) 3 phen, were synthesized under hydrothermal conditions, using europium(III) oxide (Eu 2 O 3 ), p ‐chlorocinnamic acid (PCCA), p ‐methoxy cinnamic acid (PMCA) and 1,10‐phenanthroline (phen) as raw materials. Two temperature sensitive paints (Eu(PCCA) 3 phen/PMMA and Eu(PMCA) 3 phen/PMMA) were obtained by the polymerization of methyl methacrylate (MMA) with different europium complexes. The structure, morphology, luminescent properties of the europium complexes and temperature quenching properties of the TSPs were characterized by infrared (IR) spectroscopy, scanning electron microscopy (SEM), and fluorescence spectroscopy. The fluorescence results show that both of the two TSPs have good temperature quenching performance in the range 20–100°C with high sensitivity 50–60°C and 80–90°C, respectively. Furthermore, the highest sensitivity of Eu(PCCA) 3 phen/PMMA is greater than that of Eu(PMCA) 3 phen/PMMA. This work can provide a universal way for preparing efficient TSPs in practical applications.