Abstract
Two novel core-shell structured SiO2@AIPA-S-Si-Eu and SiO2@AIPA-S-Si-Eu-phen nanocomposites have been synthesized by a bifunctional organic ligands ((HOOC)2C6H3NHCONH(CH2)3Si(OCH2CH3)3) (defined as AIPA-S-Si) connected with Eu3+ ions and silica via covalent bond. And the corresponding core-shell-shell structured SiO2@AIPA-S-Si-Eu@SiO2 and SiO2@AIPA-S-Si-Eu-phen@SiO2 nanocomposites with enhanced luminescence have been synthesized by tetraethyl orthosilicate (TEOS) hydrolysis co-deposition method. The composition and micromorphology of the nanocomposites were characterized by means of Fourier-transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX) and X-ray photoelectron spectroscopy (XPS). The as-synthesized core-shell and core-shell-shell structured nanocomposites have excellent luminescence intensity and long lifetime. The nanocomposites show bright red light under ultraviolet lamp. However, the core-shell-shell structured nanocomposites have stronger luminescence intensity than the corresponding core-shell structured nanocomposites. Meanwhile, the core-shell-shell structured nanocomposites still exhibit good luminescence stability in aqueous solution. In addition, a large number of Si-OH on the surface of the core-shell-shell structured nanocomposites can be attached to many biomacromolecules. Therefore, they have potential applications in the fields of biology and luminescence.
Highlights
Two novel core-shell structured SiO2@amino-phthalic acid (AIPA)-S-Si-Eu and SiO2@AIPA-S-Si-Eu-phen nanocomposites have been synthesized by a bifunctional organic ligands ((HOOC)2C6H3NHCONH(CH2)3Si(OCH2CH3)3) connected with Eu3+ ions and silica via covalent bond
The synthesis mechanism of the ligand AIPA-S-Si was shown in Scheme 1
The bifunctional ligand AIPA-S-Si was obtained by linking an amino group of AIPA having carboxyl group and isocyanate group of TEPIC having ethoxy group
Summary
Two novel core-shell structured SiO2@AIPA-S-Si-Eu and SiO2@AIPA-S-Si-Eu-phen nanocomposites have been synthesized by a bifunctional organic ligands ((HOOC)2C6H3NHCONH(CH2)3Si(OCH2CH3)3) (defined as AIPA-S-Si) connected with Eu3+ ions and silica via covalent bond. A large number of Si-OH on the surface of the core-shell-shell structured nanocomposites can be attached to many biomacromolecules They have potential applications in the fields of biology and luminescence. Our group reported that the core-shell structured nanocomposite SiO2@MABA-Si-Tb was synthesized by using MABA-Si as a ligand. Though the core-shell structured nanocomposite with silica coating inorganic materials were successive studied[17,18,19], but their weaker luminescent properties limit their application in many fields. The nanocomposites with silica as the core and rare earth complexes as the shell have good luminous properties, which make them more widely used. In the core-shell structured nanocomposites, the rare earth organic complex of the outer shell layer being exposed to the environment, which tends to quench the luminescence. It is important to choose a suitable silane coupling agent
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