NIR-Fluorescent Hybrid Materials of Tm(3+) Complexes Carried by Nano-SiO(2) via Improved Sol–Gel Method

Tm(3+) 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, Tm(3+) is a down-conversion fluorescent material that is unstable under high temperature and acidic conditions. Moreover, in those complex environments, the fluorescence from Tm(3+) complex is usually degraded. In this work, two kinds of near-infrared fluorescent complexes, Tm(TTA)(3)phen and Tm(DBM)(3)phen, were prepared, and the intensity of their fluorescence is compared. The fluorescence intensity at 802 nm is greatly improved compared with Tm(TTA)(3)phen, and the intensity of the emission at 1235 nm and 1400–1500 nm is also enhanced. Moreover, the emission lifetime of SiO(2)-Tm(TTA)(3)phen is 50.38 μs. Tm(TTA)(3)phen complex and SiO(2)-Tm(TTA)(3)phen hybrid materials have better fluorescence than Tm(DBM)(3)phen and SiO(2)-Tm(DBM)(3)phen. Therefore, HTTA is a better choice of organic ligands for Tm(3+). The NIR-fluorescent hybrid materials prepared have stronger fluorescence after combining with nano-SiO(2)compared with pure Tm(3+) complexes, and have stronger structural stability compared with pure nano-SiO(2).