A multicomposite P 2Mo 18 /DODA self assembled multilayer film was fabricated by casting the chloroform solutions of ionic complex between a dimethyldidecylammomium and a phosphomolybdate anion onto the borosilicate g...A multicomposite P 2Mo 18 /DODA self assembled multilayer film was fabricated by casting the chloroform solutions of ionic complex between a dimethyldidecylammomium and a phosphomolybdate anion onto the borosilicate glass and calcium fluoride substrates. Infrared spectra revealed that the Dawson strcucture characteristic of the P 2Mo 18 O 6- 62 anion was presented in the composite film. A well ordered superlattice structure, d spacing 3.59 nm, was identified by X ray diffraction. The composite film shows good photochromic properties. Under the irradiation with UV light, the transparent film changed from yellow to blue. Then, bleaching occurred when the film was in contact with ambient air or O 2 in the dark. If the UV irradiated films were stored in nitrogen, helium, argon or vacuum conditions, it could retain blue coloration for a long time. It suggests that oxygen plays an important role during the bleaching process. The photochromic mechanism of the composite film was studied by UV Vis spectra, FTIR spectra and ESR. The appearance of IVCT bands shows that electron transfer occurs between the organic substrate and heteropolyanion, converting heteropolyanions to heteropolyblues with simultaneous oxidation of the organic substrate. Observation of UV induced ESR signal suggests that electron transfer takes place in the lattice and P 2Mo 18 O 6- 62 acting as an acceptor gets electrons during UV irradiation. The changes of IR spectra for the composite film after UV irradiation are another powerful proof to identify the DODA was oxidized and P 2Mo 18 O 6- 62 was reduced in the photochronic process.展开更多
文摘A multicomposite P 2Mo 18 /DODA self assembled multilayer film was fabricated by casting the chloroform solutions of ionic complex between a dimethyldidecylammomium and a phosphomolybdate anion onto the borosilicate glass and calcium fluoride substrates. Infrared spectra revealed that the Dawson strcucture characteristic of the P 2Mo 18 O 6- 62 anion was presented in the composite film. A well ordered superlattice structure, d spacing 3.59 nm, was identified by X ray diffraction. The composite film shows good photochromic properties. Under the irradiation with UV light, the transparent film changed from yellow to blue. Then, bleaching occurred when the film was in contact with ambient air or O 2 in the dark. If the UV irradiated films were stored in nitrogen, helium, argon or vacuum conditions, it could retain blue coloration for a long time. It suggests that oxygen plays an important role during the bleaching process. The photochromic mechanism of the composite film was studied by UV Vis spectra, FTIR spectra and ESR. The appearance of IVCT bands shows that electron transfer occurs between the organic substrate and heteropolyanion, converting heteropolyanions to heteropolyblues with simultaneous oxidation of the organic substrate. Observation of UV induced ESR signal suggests that electron transfer takes place in the lattice and P 2Mo 18 O 6- 62 acting as an acceptor gets electrons during UV irradiation. The changes of IR spectra for the composite film after UV irradiation are another powerful proof to identify the DODA was oxidized and P 2Mo 18 O 6- 62 was reduced in the photochronic process.
