Two novel core-shell composites SiO₂@PMDA-Si-Tb, SiO₂@PMDA-Si-Tb-phen with SiO₂ as the core and terbium organic complex as the shell, were successfully synthesized. The terbium ion was coordinated with organic ligand forming terbium organic complex in the shell layer. The bi-functional organosilane ((HOOC)₂C₆H₂(CONH(CH₂)₃Si(OCH₂CH₃)₃)₂ (abbreviated as PMDA-Si) was used as the first ligand and phen as the second ligand. Furthermore, the silica-modified SiO₂@PMDA-Si-Tb@SiO₂ and SiO₂@PMDA-Si-Tb-phen@SiO₂ core-shell-shell composites were also synthesized by sol-gel chemical route. An amorphous silica shell was coated around the SiO₂@PMDA-Si-Tb and SiO₂@PMDA-Si-Tb-phen core-shell composites. The core-shell and core-shell-shell composites both exhibited excellent luminescence in solid state. The luminescence of core-shell-shell composites was stronger than that of core-shell composites. Meanwhile, an improved luminescence stability property for the core-shell-shell composites was found in the aqueous solution. The core-shell-shell composites exhibited bright luminescence, high stability, long lifetime, and good solubility, which may present potential applications in the bio-medical field.
Keywords: 2,5-bis((3-(triethoxysilyl)propyl)carbamoyl)terephthalic acid (PMDA-Si); core-shel-shell composite; core-shell composite; lifetime; photoluminescence; silica shell.