Wen-Xian Li

The Studies of Enhanced Fluorescence in the Two Novel Ternary Rare-Earth Complex Systems

Two novel ternary rare-earth complexes SmL5·L’·(ClO4)2·7H2O and EuL5·L’·(ClO4)2·6H2O (the first ligand L = C6H5COCH2SOCH2COC6H5, the second ligand L’ = C6H4OHCOO−) were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC, 1HNMR and UV spectra. The detailed luminescence studies on the rare-earth complexes showed that the ternary rare-earth complexes presented stronger fluorescence intensities, longer lifetimes, and higher fluorescence quantum efficiencies than the binary rare-earth materials. After the introduction of the second ligand salicylic acid group, the relative emission intensities and fluorescence lifetimes of the ternary complexes LnL5·L’·(ClO4)2·nH2O (Ln = Sm, Eu; n = 7, 6) enhanced more obviously than the binary complexes LnL5·(ClO4)3·2H2O. This indicated that the presence of both organic ligand bis(benzoylmethyl) sulfoxide and the second ligand salicylic acid could sensitize fluorescence intensities of rare-earth ions, and the introduction of salicylic acid group was a benefit for the fluorescence properties of the ternary rare-earth complexes. The fluorescence spectra, fluorescence lifetime and phosphorescence spectra were also discussed.

Synthesis and fluorescence properties of lanthanide (III) perchlorate complexes with bis(benzoylmethyl) sulfoxide.

A ligand with two carbonyl groups and one sulfinyl group has been synthesized by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DSC, 1H NMR and UV spectra. The results indicated that the composition of these complexes is REL5(ClO4)3·3H2O (RE = La(III), Pr(III), Eu(III), Tb(III), Yb(III), L = C6H5COCH2SOCH2COC6H5). The fluorescent spectra illustrate that both the Tb (III) and Eu (III) complexes display characteristic metal-centered fluorescence in solid state, indicating the ligand favors energy transfer to the excitation state energy level of them. However, the Tb (III) complex displays more effective luminescence than the Eu (III) complex, which is attributed to especial effectively in transferring energy from the average triplet energy level of the ligands (T) onto the excited state (5D4) of Tb (III) than that (5D0) of Eu (III), showing a good antenna effect for Tb(III) luminescence. The phosphorescence spectra and the relationship between fluorescence lifetimes and fluorescence intensities were also discussed.

Synthesis and Luminescence Properties of Two Novel Lanthanide (III) Perchlorate Complexes with Bis(benzoylmethyl) Sulfoxide and Benzoic Acid

Two novel ternary rare earth complexes of Tb(III) and Dy(III) perchlorates with bis(benzoylmethyl) sulfoxide (L) and benzoic acid (L′) had been synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC, 1HNMR and UV spectra. The results indicated that the composition of these complexes was REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III); L=C6H5COCH2SOCH2COC6H5, L′=C6H5COO; n = 6,8). The fluorescence spectra illustrated that the ternary rare earth complexes presented stronger fluorescence intensities, longer lifetimes and higher fluorescence quantum efficiencies than the binary rare earth complexes REL5·(ClO4)3·2H2O. After the introduction of the second ligand benzoic acid group, the relative fluorescence emission intensities and fluorescence lifetimes of the ternary complexes REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III)) enhanced more obviously than the binary complexes. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand benzoic acid could sensitize fluorescence intensities of rare earth ions, and the introduction of benzoic acid group was resulted in the enhancement of the fluorescence properties of the ternary rare earth complexes. The phosphorescence spectra were also discussed.

Synthesis and Fluorescence Properties of Lanthanide (III) Perchlorate Complexes with Naphthyl-Naphthalinesulphonylpropyl Sulfoxide

A ligand with double sulfinyl groups, naphthyl-naphthalinesulphonylpropyl sulfoxide(dinaphthyl disulfoxide, L), was synthesized by a new method and its several lanthanide (III) complexes were synthesized and characterized by element analysis, molar conductivity, coordination titration analysis, IR, TG-DTA, 1HNMR and UV spectra. The composition of these complexes, were RE2(ClO4)6·(L)5·nH2O (RE = La, Nd, Eu, Tb, Yb, n = 2 ∼ 6, L = C10H7SOC3H6SOC10H7). The fluorescent spectra illustrated that the Eu (III) complex had an excellent luminescence. It was supposed that the ligand was benefited for transferring the energy from ligand to the excitation state energy level (5D0) of Eu (III). The Tb (III) complex displayed weak luminescence, which attributed to low energy transferring efficiency between the average triplet state energy level of ligand and the excited state (5D4) of Tb (III). So the Eu (III) complex displayed a good antenna effect for luminescence. The phosphorescence spectra and the relationship between fluorescence lifetime and fluorescence intensity were also discussed.

Fluorescence enhancement of europium (III) perchlorate by 1,10-phenanthroline on the 1-(naphthalen-2-yl)-2-(phenylsulthio)ethanone complex and luminescence mechanism

A novel ligand, 1-(naphthalen-2-yl)-2-(phenylsulthio)ethanone was synthesized using a new method and its two europium (Eu) (III) complexes were synthesized. The compounds were characterized by elemental analysis, coordination titration analysis, molar conductivity, infrared, thermo gravimetric analyzer-differential scanning calorimetry (TGA-DSC), (1)H NMR and UV spectra. The composition was suggested as EuL5 · (ClO4)3 · 2H2O and EuL4 · phen(ClO4)3 · 2H2O (L = C(10)H(7)COCH(2)SOC(6)H(5)). The fluorescence spectra showed that the Eu(III) displayed strong characteristic metal-centered fluorescence in the solid state. The ternary rare earth complex showed stronger fluorescence intensity than the binary rare earth complex in such material. The strongest characteristic fluorescence emission intensity of the ternary system was 1.49 times as strong as that of the binary system. The phosphorescence spectra were also discussed.

Synthesis and luminescence properties of two novel lanthanide (III) complexes of acetophenonylcarboxymethyl sulphoxide

A novel ligand containing multiple coordinating groups (sulfinyl, carboxyl and carbonyl groups), acetophenonylcarboxymethyl sulphoxide, was synthesized. Its corresponding two lanthanide (III) binary complexes were synthesized and characterized by element analysis, molar conductivity, FT-IR, TG-DTA and UV spectroscopy. Results showed that the composition of these complexes was REL3 L(-) (ClO4)2 · 3H2O (RE = Eu (III), Tb (III); L = C6 H5 COCH2 SOCH2 COOH; L(-) = C6H5 COCH2 SOCH2 COO(-)). FT-IR results indicated that acetophenonylcarboxymethyl sulphoxide was bonded with an RE (III) ion by an oxygen atom of the sulfinyl and carboxyl groups and not by an oxygen atom of the carbonyl group due to high steric hinderance. Fluorescent spectra showed that the Tb (III) complex had excellent luminescence as a result of a transfer of energy from the ligand to the excitation state energy level ((5)D4) of Tb (III). The Eu (III) complex displayed weak luminescence, attributed to low energy transfer efficiency between the triplet state energy level of its ligand and the excited state ((5)D0 ) of Eu (III). As a result, the Tb (III) complex displayed a good antenna effect for luminescence. The fluorescence decay curves of Eu (III) and Tb (III) complexes were also measured.

Preparation, characterization and luminescence properties of core–shell ternary terbium composites SiO2(600)@Tb(MABA-Si)•L

Two novel core–shell structure ternary terbium composites SiO2(600)@Tb(MABA-Si)·L(L:dipy/phen) nanometre luminescence materials were prepared by ternary terbium complexes Tb(MABA-Si)·L2·(ClO4)3·2H2O shell grafted onto the surface of SiO2 microspheres. And corresponding ternary terbium complexes were synthesized using (CONH(CH2)3Si(OCH2CH3)3)2 (denoted as MABA-Si) as first ligand and L as second ligand coordinated with terbium perchlorate. The as-synthesized products were characterized by means of IR spectra, 1HNMR, element analysis, molar conductivity, SEM and TEM. It was found that the first ligand MABA-Si of terbium ternary complex hydrolysed to generate the Si–OH and the Si–OH condensate with the Si–OH on the surface of SiO2 microspheres; then ligand MABA-Si grafted onto the surface of SiO2 microspheres. The diameter of SiO2 core of SiO2(600)@Tb(MABA-Si)·L was approximately 600 nm. Interestingly, the luminescence properties demonstrate that the two core–shell structure ternary terbium composites SiO2(600)Tb(MABA-Si)·L(dipy/phen) exhibit strong emission intensities, which are 2.49 and 3.35 times higher than that of the corresponding complexes Tb(MABA-Si)·L2·(ClO4)3·2H2O, respectively. Luminescence decay curves show that core–shell structure ternary terbium composites have longer lifetime. Excellent luminescence properties enable the core–shell materials to have potential applications in medicine, industry, luminescent fibres and various biomaterials fields.

Preparation, and Luminescence Properties of SiO2@Sm(MABA-Si)phen Core-Shell Structure Nanometer Composite

A novel ternary samarium complex was prepared using HOOCC6H4N(CONH(CH2)3Si(OCH2CH3)3)2 (MABA-Si) as first ligand, and phen as second ligand. The corresponding SiO2@Sm(MABA-Si)phen core-shell structure nanometer composite was synthesized as well, and the silica spheres was the core, and the ternary samarium complex was the shell layer. The ternary samarium complex has been characterized by element analysis, molar conductivity and IR spectra. The results show that the chemical formula of the complex is Sm(MABA-Si)(phen)2(ClO4)3·2H2O. The fluorescent spectra illustrat that the luminescence properties of the samarium complex are superior. The core-shell structure of SiO2@Sm(MABA-Si)phen nanometer composite is characterized by SEM, TEM and IR spectra. The SiO2@Sm(MABA-Si)phen core-shell structure composites exhibit stronger emission intensity than the ternary samarium complex. The fluorescence lifetime of the complex and core-shell structure composite is measured as well.

Synthesis and photoluminescence properties of novel core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-spheres

A novel core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-sphere was controllably synthesized by a bridging ligand organosilane HOOCC6H4N(CONH(CH2)3Si(OCH2CH3)3)2 (MABA-Si) connecting the silica core and rare earth ions. The as-synthesized samples were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (IR). It is found that SiO2@CePO4:Tb@SiO2 has a ∼25 nm outermost shell, a ∼4 nm intermediate shell, and a ∼200 nm core. SiO2@CePO4:Tb@SiO2 exhibits stable photoluminescence properties in aqueous solution: its photoluminescence intensity was unquenched even after 15 days. The core–shell–shell submicro-spheres were found to have better photoluminescence than the core–shell submicro-spheres because the SiO2 shell protected the phosphor materials and then improved its photoluminescence intensity and biocompatibility. A formation mechanism of the core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-spheres was proposed. Thus, the low-cost preparation of the core–shell–shell SiO2@CePO4:Tb@SiO2 submicro-spheres could be rationally achieved using SiO2.

Fluorescence Enhancement of Europium(III) Perchlorate by Salicylic Acid on Phenyl-Naphthoylmethyl Sulfoxide Complex and Luminescence Mechanism

A novel ligand, phenyl-naphthoylmethyl sulfoxide, was synthesized. Its novel ternary complex and a novel binary complex had been synthesized (salicylic acid as the second ligand), and characterized by elemental analysis, molar conductivity, coordination titration analysis, FTIR and TG-DSC. The fluorescence spectra, fluorescence lifetime and phosphorescence spectra were also discussed.