Synthesis and visible-light photochromism of a new composite based on polymolybdate enclosed in magadiite.

A new composite based on polymolybdate incorporated in layered magadiite has been synthesized via a exfoliation/self-assembly process. Various techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX), Raman spectroscopy, thermogravimetric (TG) analysis, UV-vis spectroscopy, and transmission electron microscopy (TEM), have been employed to characterize the composite. Results indicated that the polymolybdate particles were incorporated into the layered magadiite. Upon the irradiation of visible light (420-630 nm), the composite changed color from yellow to dark blue; moreover, the color can be bleached upon exposure to a 15% H2O2 solution. The visible-light illumination and H2O2 treatment can be repeated in excess of 10 times. The mechanism of photochromism has been investigated, and the reversibility is attributed to the hydration property of host magadiite and oxidative ability of H2O2 solution.

Eu-doped Mg-Al layered double hydroxide as a responsive fluorescent material and its interaction with glutamic acid.

The paper describes a study on the fluorescence of a Eu-doped Mg-Al layered double hydroxide (Eu-doped LDH) response to glutamic acid (Glu). Various characterizations (UV-Vis transmittance, TG-DTA and IR-spectrum) indicated that there is an interaction between the Eu-doped LDH and Glu. Fluorescent study was found that the red emissions resulted from (5)D(0)-(7)F(J) transition (J=1, 2) of Eu(3+) markedly decreased, while the blue emission at 440 nm contributed to Glu shifted to low energy after the addition of Glu to the Eu-doped LDH. The fluorescent changes may be relevant to the hydrogen-bond interaction between the Eu-doped LDH and Glu, and the mechanism of the interaction between Eu-doped LDH and Glu was discussed.

Fluorescence of Zn-Al-Eu ternary layered hydroxide response to phenylalanine.

We reported the fluorescence of a Zn-Al-Eu ternary layered double hydroxide (LDH) response to an amino acid (phenylalanine) for the first time. As shown in fluorescence, the red emissions attributed to (5)D(0)-(7)F(J) transitions (J=1, 2, 3, 4) of Eu(3+) ions were quenched by the phenylalanine (Phe), and a strong blue emission at around 445 nm appeared. The fluorescent changes may be due to ligand-to-metal charges transfer, which was caused by the interaction between the Zn-Al-Eu LDH and Phe. This interaction was manifested by markedly different chemical shift positions of the Zn 3p(3/2), Al 2p, Eu 4d(3/2), O 1s, and C 1s peaks in the XPS spectra from those of the Zn-Al-Eu LDH and Zn-Al-Eu/Phe composite. Furthermore, the interaction between the LDH and Phe was supported by the results of X-ray diffraction (XRD) measurements, Fourier transform infrared (FT-IR) spectra, and thermogravimetric and differential thermogravimetric (TG-DTG) analysis. The fluorescence of Zn-Al-Eu LDH response to Phe may be potential application in biological techniques.