Abstract
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.
Highlights
Core–shell nanostructured composite materials, which connect different functional components integrated into one unit, have attracted increased attention owing to their interesting properties and broad range of applications in catalysis [1,2,3,4,5,6], bio-nanotechnology [7,8,9,10,11], materials chemistry [12], optical devices [13,14,15,16,17,18,19], electronics [20,21,22,23] and magnetic devices [24,25,26,27,28]
The synthesis strategy for fabricating core–shell and core–shell–shell nanostructured composites is presented in scheme 1
In order to see the details of photoluminescence property of terbium core–shell and core–shell–shell nanostructured composites, the photoluminescence lifetime curves of SiO2@After surface modification with organosilane (ANA-Si)-Tb-phen and SiO2@ANA-Si-Tb-phen@SiO2 are recorded as shown in figure 13
Summary
Core–shell nanostructured composite materials, which connect different functional components integrated into one unit, have attracted increased attention owing to their interesting properties and broad range of applications in catalysis [1,2,3,4,5,6], bio-nanotechnology [7,8,9,10,11], materials chemistry [12], optical devices [13,14,15,16,17,18,19], electronics [20,21,22,23] and magnetic devices [24,25,26,27,28]. The surface of SiO2 has many active hydroxyl groups and can be chemically bonded to a substance with a functional property These core–shell nanostructured composites keep core materials stable and have shell layer-specific physico-chemical properties. The Si–O–Si chemical bonds are constructed after hydrolysis and polycondensation processes of X groups and the hydroxyl of SiO2 surface In such a method, the silane coupling agent connects SiO2 spheres and rare earth complexes together. The silica shell plays an important role in preventing rare earth core–shell nanostructured composites from quenching of external environment and improving the solubility and luminescent stability of the core–shell nanostructured composite material. The silica-modified sol– gel technique is an ideal option to improve luminescent stability and the solubility of rare earth core– shell nanostructured composites Such silica-modified core–shell–shell nanostructured composites simultaneously show excellent properties with regard to non-toxicity and luminescence pyridine. The silicamodified SiO2@ANA-Si-Tb@SiO2 and SiO2@ANA-Si-Tb-L@SiO2 core–shell–shell nanostructured composites were extending their potential application in photonics-based biomedical sciences
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