Abstract
Tm3+ has obvious emission characteristics in the near-infrared band. Thulium ions combined with different organic ligands lead to different fluorescent properties. In the near-infrared region, Tm3+ is a down-conversion fluorescent material that is unstable under high temperature and acidic conditions. Moreover, in those complex environments, the fluorescence from Tm3+ complex is usually degraded. In this work, two kinds of near-infrared fluorescent complexes, Tm(TTA)3phen and Tm(DBM)3phen, were prepared, and the intensity of their fluorescence is compared. The fluorescence intensity at 802 nm is greatly improved compared with Tm(TTA)3phen, and the intensity of the emission at 1235 nm and 1400–1500 nm is also enhanced. Moreover, the emission lifetime of SiO2-Tm(TTA)3phen is 50.38 μs. Tm(TTA)3phen complex and SiO2-Tm(TTA)3phen hybrid materials have better fluorescence than Tm(DBM)3phen and SiO2-Tm(DBM)3phen. Therefore, HTTA is a better choice of organic ligands for Tm3+. The NIR-fluorescent hybrid materials prepared have stronger fluorescence after combining with nano-SiO2compared with pure Tm3+ complexes, and have stronger structural stability compared with pure nano-SiO2.
Highlights
Rare earth ions complexes have special physical and chemical properties, which have attracted much attention thanks to their high purity, narrow emissivity, and high internal quantum efficiency
According to the element composition obtained by EDS, F and S elements belong to HTTA, while N elements belong to Phen
SiO2-Tm(TTA/DBM)3phen NIR-fluorescent hybrid materials were prepared by an improved sol–gel method
Summary
Rare earth ions complexes have special physical and chemical properties, which have attracted much attention thanks to their high purity, narrow emissivity, and high internal quantum efficiency. In the preparation of many fluorescent materials, rare earth ions cannot be prepared at a high temperature, and the solution concentration should be controlled. Owing to the large amount of coordination with rare earth ions, complexes are easy to coordinate with solution molecules, resulting in fluorescence quenching, and a decrease of the thermal stability. High transparency, good rigidity, and three-dimensional network void structure of nano-SiO2 is chosen as the matrix, which can protect the stability of rare earth ions complexes, and keep or increase the fluorescence of hybrid materials. In order to reduce the influence of H2O on the fluorescence of Tm(TTA/DBM)3phen, we have improved the experimental method for preparing nano-SiO2, and changed the size of nano-SiO2 by adjusting the dosage of NH3·H2O. Infrared fluorescent materials with good fluorescence properties provide favorable conditions for the development of biomedical and food detection
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