Tris, di-( organotitanium) substituted tungstosilicates α,β - (CpTi)3(SiW9037)17– and γ-[(CpTi)2(SiW10O38)] 6– were prepared by the reaction of C2TiC12 (Cp= η-C5H5) with a,β-SiW9 O9/34(noted α,β Siv9,), γ-Si...Tris, di-( organotitanium) substituted tungstosilicates α,β - (CpTi)3(SiW9037)17– and γ-[(CpTi)2(SiW10O38)] 6– were prepared by the reaction of C2TiC12 (Cp= η-C5H5) with a,β-SiW9 O9/34(noted α,β Siv9,), γ-SiWO8/36 (noted γ-SiW10) The products were characterized by means of elemental analysis, IR, 1H NMR, 183W NMR and polarography. 183W NMR spectra of the complexes support the stoichiometry of the new heteropolyanions and the probable retention of the A-XW9 or γ-SiWlO units. And the organotitanium substituted compounds showed promising in vitro antitumor activity in two of human tumor cell lines.展开更多
A novel reversible photochromic nanocomposite film based on a hybrid inorganic-organic matrix in which heteropolyacid H4SiW12O40 （SiWA） was entrapped in Si-O-Ti network was prepared. Structure, photochromic behavior...A novel reversible photochromic nanocomposite film based on a hybrid inorganic-organic matrix in which heteropolyacid H4SiW12O40 （SiWA） was entrapped in Si-O-Ti network was prepared. Structure, photochromic behaviors and mechanism of the film were investigated by means of infrared spectroscopy （IR）, ultraviolet-visible （UV-Vis） absorption spectra and electron spin resonance （ESR）. The results showed that heteropolyanion i.e. SiW12O^4- 40 （SiW12）, maintained a Keggin structure in the film and there was a strong interaction between anion SiW12 and cation R-NH^＋3 （R=link of hybrid composite）. The photochromic properties of the composite film originated from reversible charge transfer between the anions and cations. Under UV irradiation, the anion would be reduced via one-electron step with simultaneous oxidation of the cation, accompanied by a color change from colorless to blue. Bleaching could occur when the film was in contact with ambient air or 02 in the dark.展开更多
The present paper covers seven rare earth-containing tungstosilicate heteropoly complexes LnHSiW_(12)O_(40)·xH_2O with Keggin structure(Ln=La,Ce,Pr,Nd,Sm,Eu and Gd)snythesized by double decomposition reaction.The...The present paper covers seven rare earth-containing tungstosilicate heteropoly complexes LnHSiW_(12)O_(40)·xH_2O with Keggin structure(Ln=La,Ce,Pr,Nd,Sm,Eu and Gd)snythesized by double decomposition reaction.The synthesized heteropoly complexes were characterized by ICP,^(29)Si-NMR,XPS, XRD,IR,UV,polarogram,CV and TG-DTA.The relationship between the structure of the synthesized heteropoly complexes and their properties is discussed.展开更多
A novel inorganic-organic nanocomposite film was prepared and characterized by IR, UV-Vis, XRD and DTA-TG. IR and UV-Vis spectra show that the Keggin structure of SiW 12O 4- 40 polyanion is preserved in the composite ...A novel inorganic-organic nanocomposite film was prepared and characterized by IR, UV-Vis, XRD and DTA-TG. IR and UV-Vis spectra show that the Keggin structure of SiW 12O 4- 40 polyanion is preserved in the composite film and there is an interaction between H 4SiW 12O 40 and the organic substrate. The composite film showed a reversible photochromism. Under UV irradiation, the composite film turns blue and charge transfer occurs by oxidation of R-NH + 3 and reduction of SiW 12O 4- 40. When the irradiated samples are placed in air and sheltered from the light, they change back to their original color, and recover again when being exposed to UV light.展开更多
Er3＋-Yb3＋ codoped oxy-fluoro-tungstosilicate glasses with infrared-to-visible frequency upconversion luminescence were prepared by melting quenching in air.The effects of Er3＋ doping on the optical properties of th...Er3＋-Yb3＋ codoped oxy-fluoro-tungstosilicate glasses with infrared-to-visible frequency upconversion luminescence were prepared by melting quenching in air.The effects of Er3＋ doping on the optical properties of the samples were measured by means of techniques such as optical absorption spectra and photoluminescence spectra.The results showed that intense green and red signals centered at 546 and 665 nm,corresponding to the 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3＋ by a multiphoton stepwise phonon-assisted excited-state absorption process,respectively,were simultaneously observed by exciting the samples with a diode laser operating at 980 nm at room temperature.The upconversion process was found very sensitive to Er3＋ content at a constant Yb2O3 content of 5 mol.%.With the increase of Er3＋ content from 0.5% to 1.5%,the upconversion intensity increased gradually.Further increasing of Er3＋ content to 3.0% resulted in a significant fluorescence quenching.Moreover,the possible upconversion mechanisms were discussed based on the energy-matching conditions and the quadratic dependence on excitation power.展开更多
文摘Tris, di-( organotitanium) substituted tungstosilicates α,β - (CpTi)3(SiW9037)17– and γ-[(CpTi)2(SiW10O38)] 6– were prepared by the reaction of C2TiC12 (Cp= η-C5H5) with a,β-SiW9 O9/34(noted α,β Siv9,), γ-SiWO8/36 (noted γ-SiW10) The products were characterized by means of elemental analysis, IR, 1H NMR, 183W NMR and polarography. 183W NMR spectra of the complexes support the stoichiometry of the new heteropolyanions and the probable retention of the A-XW9 or γ-SiWlO units. And the organotitanium substituted compounds showed promising in vitro antitumor activity in two of human tumor cell lines.
文摘A novel reversible photochromic nanocomposite film based on a hybrid inorganic-organic matrix in which heteropolyacid H4SiW12O40 （SiWA） was entrapped in Si-O-Ti network was prepared. Structure, photochromic behaviors and mechanism of the film were investigated by means of infrared spectroscopy （IR）, ultraviolet-visible （UV-Vis） absorption spectra and electron spin resonance （ESR）. The results showed that heteropolyanion i.e. SiW12O^4- 40 （SiW12）, maintained a Keggin structure in the film and there was a strong interaction between anion SiW12 and cation R-NH^＋3 （R=link of hybrid composite）. The photochromic properties of the composite film originated from reversible charge transfer between the anions and cations. Under UV irradiation, the anion would be reduced via one-electron step with simultaneous oxidation of the cation, accompanied by a color change from colorless to blue. Bleaching could occur when the film was in contact with ambient air or 02 in the dark.
文摘The present paper covers seven rare earth-containing tungstosilicate heteropoly complexes LnHSiW_(12)O_(40)·xH_2O with Keggin structure(Ln=La,Ce,Pr,Nd,Sm,Eu and Gd)snythesized by double decomposition reaction.The synthesized heteropoly complexes were characterized by ICP,^(29)Si-NMR,XPS, XRD,IR,UV,polarogram,CV and TG-DTA.The relationship between the structure of the synthesized heteropoly complexes and their properties is discussed.
文摘A novel inorganic-organic nanocomposite film was prepared and characterized by IR, UV-Vis, XRD and DTA-TG. IR and UV-Vis spectra show that the Keggin structure of SiW 12O 4- 40 polyanion is preserved in the composite film and there is an interaction between H 4SiW 12O 40 and the organic substrate. The composite film showed a reversible photochromism. Under UV irradiation, the composite film turns blue and charge transfer occurs by oxidation of R-NH + 3 and reduction of SiW 12O 4- 40. When the irradiated samples are placed in air and sheltered from the light, they change back to their original color, and recover again when being exposed to UV light.
基金supported by the Fundamental Research Funds for the Central Universities
文摘Er3＋-Yb3＋ codoped oxy-fluoro-tungstosilicate glasses with infrared-to-visible frequency upconversion luminescence were prepared by melting quenching in air.The effects of Er3＋ doping on the optical properties of the samples were measured by means of techniques such as optical absorption spectra and photoluminescence spectra.The results showed that intense green and red signals centered at 546 and 665 nm,corresponding to the 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions of Er3＋ by a multiphoton stepwise phonon-assisted excited-state absorption process,respectively,were simultaneously observed by exciting the samples with a diode laser operating at 980 nm at room temperature.The upconversion process was found very sensitive to Er3＋ content at a constant Yb2O3 content of 5 mol.%.With the increase of Er3＋ content from 0.5% to 1.5%,the upconversion intensity increased gradually.Further increasing of Er3＋ content to 3.0% resulted in a significant fluorescence quenching.Moreover,the possible upconversion mechanisms were discussed based on the energy-matching conditions and the quadratic dependence on excitation power.
