title: Rare earth hybrid materials of organically modified silica covalently bonded to a GaN matrix: multicomponent assembly and multi-color luminescence.
abstract: Three kinds of rare earth hybrid materials with enhanced thermostability and photoluminescence properties have been prepared for the first time by using a functionalized GaN matrix as one of the building blocks. A number of silane coupling agents (isocyanate triethoxysilane (ICTES), 3-chloropropyl triethoxysilane (CPTES) and 3-aminopropyl triethoxysilane (APTES)) behave as the covalent linkages for modification by both hydroxylation of GaN and functionalized photoactive ligands (4-mercaptobenzoic acid (MBA), 4-hydroxybenzoic acid (HBA) and nitrobenzoyl chloride (NBC)), resulting in the precursors (MBA-ICTES-GaN, HBA-CPTES-GaN and NBC-APTES-GaN). Subsequently, multicomponent photofunctional rare earth hybrid materials with the three precursors and 1,10-phenanthroline (Phen) are assembled and characterized by their FTIR spectra, UV-vis diffuse reflectance spectra, XRD patterns, and photoluminescent behaviour (luminescence, lifetime, quantum efficiency, and energy transfer). These results reveal that the Eu(3+) hybrids with the MBA-ICTES-GaN unit have a better luminescence intensity ratio, higher quantum efficiency and longer lifetime than those with the HBA-CPTES-GaN and NBC-APTES-GaN units. Meanwhile the hybrid Phen-Tb-HBA-CPTES-GaN possesses a stronger characteristic emission of Tb(3+) ions than the other two hybrids (Phen-Tb-MBA-ICTES-GaN and Phen-Tb-NBC-APTES-GaN). Moreover, two-color-based hybrid materials are fabricated by combining different molar ratios of Eu(3+) and Tb(3+) in the same system (Phen-RE-MBA-ICTES-GaN) with emission at a wavelength of 331 nm (RE = Eu, Tb) and yellow luminescence can be achieved.
authors.affiliation: Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Bing
authors.initials: B
authors.lastname: Yan