Preparation And Temperature Sensitive Properties Of Rare Earth Complexes With Double Ligands

Temperature sensitive paint technology has been widely used in measure the temperature field distribution on the windward side of high-speed moving targets such as airplanes,automobiles,and high-speed rail vehicles.Among them,the luminescent probe with high fluorescence intensity is the core component of the temperature sensitive paint.In this work,the luminescent rare earth ion Eu³⁺is selected as the central ion,and the aromatic carboxylic acid p-chlorocinnamic acid(PCCA),p-methoxycinnamic acid(PMCA),and p-trifluoromethyl cinnamic acid(PTCA)are the first ligands,respectively.1,10-Phenanthroline(phen)is the second ligand,and three duals ligands rare earth complexes Eu(PCCA)₃phen,Eu(PMCA)₃phen and Eu(PTCA)₃phen are synthesized,all of which have strong red light emission.Afterwards,the above three complexes were doped with non-luminescent rare earth ions(La³⁺/Gd³⁺).The six series of doped rare earth complexes were obtained,which are Eu_xLa_1-x(PCCA)₃phen,Eu_xGd_1-x(PCCA)₃phen,Eu_xLa_1-x(PMCA)₃phen,Eu_xGd_1-x(PMCA)₃phen,Eu_xLa_1-x(PTCA)₃phen and Eu_xGd_1-x(PTCA)₃phen,respectively.Eu_0.5La_0.5(PCCA)₃phen,Eu_0.5Gd_0.5(PCCA)₃phen,Eu_0.5La_0.5(PMCA)₃phen,Eu_0.5Gd_0.5(PMCA)₃phen,Eu_0.6La_0.4(PTCA)₃phen and Eu_0.6Gd_0.4(PTCA)₃phen have the strongest luminescent in the correspond doping system respectively,having done the main research.The above mentioned nine complexes were used as probe molecules and methyl methacrylate was polymerized to make temperature sensitive paints.The structure,morphology and luminescence performance of the complexes,as well as the temperature sensitive characteristics and recycling performance of the temperature sensitive paints were analyzed.Infrared spectra showed that the complexes Eu(PCCA)₃phen,Eu(PMCA)₃phen and Eu(PTCA)₃phen have been successfully synthesized,and the rare earth ions(La³⁺/Gd³⁺)doping did not change Eu(PCCA)₃phen,Eu(PMCA)₃phen and Eu(PTCA)₃phen.The structure of Scanning electron micrographs showed that the incorporation of La³⁺/Gd³⁺ion did not change the morphology of the complex.Energy spectrum and elemental analysis showed that La³⁺/Gd³⁺ion had successfully replaced part of Eu³⁺ion.Fluorescence spectra showed that all nine complexes showed Eu³⁺ion characteristic emission peaks,and La³⁺/Gd³⁺ion doping all had a fluorescence gain effect on the complexes.The nine kinds of temperature sensitive paints prepared show good temperature sensitive characteristics in the temperature range of 20??100?,and have high temperature measurement sensitivity.Furthermore,ZIF-8 was used to encapsulate Eu(PCCA)₃phen,Eu(PMCA)₃phen and Eu(PTCA)₃phen to form composite materials Eu(PCCA)₃phen@ZIF-8,Eu(PMCA)₃phen@ZIF-8 and Eu(PTCA)₃phen@ZIF-8.The characteristic peaks of the complex and ZIF-8 can be observed by infrared spectroscopy,and only the morphology of ZIF-8 can be observed in the scanning electron microscope photos,indicating that the complex has been successfully encapsulated into ZIF-8.Fluorescence spectra show that as the loading of complexes increases,the intensity of the fluorescence emission peak also increases.It is the first attempt to prepare a temperature-sensitive paint with three composite materials,which shows good temperature quenching performance in the temperature range of 20??100?.