NIR-Fluorescent Hybrid Materials of Tm3+ Complexes Carried by Nano-SiO2 via Improved Sol–Gel Method

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&ndash
1500 nm is also enhanced. Moreover, the emission lifetime of SiO2-Tm(TTA)3phen is 50.38 &mu
s. 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.