Supplementary material from "Synthesis and photoluminescence properties of silica-modified SiO₂@ANA-Si-Tb@SiO₂, SiO₂@ANA-Si-Tb-L@SiO₂ core–shell–shell nanostructured composites"

Three novel core–shell nanostructured composites SiO₂@ANA-Si-Tb, SiO₂@ANA-Si-Tb-L (L = second ligand) with SiO₂ as the core and terbium organic complex as the shell were successfully synthesized. The core and shell were connected together by covalent bonds. The terbium ion was coordinated with organic ligand-forming terbium organic complex in the shell layer. The organosilane (HOOCC₅H₄NN(CONH(CH₂)₃Si(OCH₂CH₃)₃)₂ (abbreviated as ANA-Si) was used as the first ligand and 1, 10-phenanthroline (phen) or 2-thenoyltrifluoroacetone (TTA) was used as the second ligand. Furthermore, silica-modified SiO₂@ANA-Si-Tb@SiO₂, SiO₂@ANA-Si-Tb-L@SiO₂ core–shell–shell nanostructured composites were also synthesized by sol–gel chemical route, which involved the hydrolysis and polycondensation processes of tetraethoxysilane (TEOS) using cetyltrimethyl ammonium bromide (CTAB) as a surface-active agent. An amorphous silica shell was coated around the SiO₂@ANA-Si-Tb, SiO₂@ANA-Si-Tb-L core–shell nanostructured composites. The core–shell and core–shell–shell nanostructured composites exhibited excellent luminescence in the solid state. Meanwhile, an improved luminescent stability property of the core–shell–shell nanostructured composites was observed for the aqueous solution. This type of core–shell–shell nanostructured composites exhibited bright luminescence, high stability and good solubility, which may present potential applications in the fields of optoelectronic devices, bio-imaging, medical diagnosis and study on the structure of function composite materials.