Advanced Materials Research Vols. 393-395

Abstract: A new photochromic diarylethene compound, 1-(2-methylphenyl)-2-[5-(2-pyridine)-2-methyl-3-thienyl]perfluorocyclopentene (1a) was synthesized. its photochromic and fluorescent properties have been investigated in detail. Meanwhile, fluorescence properties in different solution have also been discussed. The results of the research demonstrated that it has shown good photochromic behavior and relatively strong fluorescence in different solution and in PMMA at room temperature. Finally, photo-mode rewritable optical storage using 1b was performed. The images demonstrated that the compound can be used as optical storage material.

Abstract: A new unsymmetrical photochromic diarylethene 1-(2,4-dimethyl-3-isoxazol)-2-[2-methyl-5-(2-methyl)-3-thienyl]perfluorocyclopentene (1a) has been synthesized. Its photochromic properties in solution and PMMA film were investigated. Diarylethene 1a changed the color from colorless to pink upon irradiation with 297 nm UV light, in which absorption maxima were observed at 518 nm in hexane and at 527 nm in PMMA film, respectively. In hexane solution, the open-ring isomer of the diarylethene 1 exhibited relatively fluorescence at 386 nm when excited at 309 nm.

Abstract: A novel red long persistent phosphor of Sr₂ZnSi₂O₇: Eu³⁺, Lu³⁺ was successfully synthesized with sol–gel method. Its properties were systematically characterized by X-ray diffraction(XRD), luminescence, afterglow decay curves and thermoluminescence (TL) spectra. The red phosphor showed one emission peak at 616.9nm, which is attributed to the typical ⁵D₀–⁷F₂ transition of Eu3+ ions as luminescent centers in Sr₂ZnSi₂O₇ host. Lu³⁺ as a sensitized ion played an important role in enhancing the long afterglow performance of Sr₂ZnSi₂O₇: Eu³⁺, Lu³⁺. Under UV light irradiation, this phosphor showed obvious red long-lasting phosphorescence that can be clearly seen with naked eyes in a dark room for over 20s after the irradiation source has been removed. Thermoluminescence (TL) measurement showed that Lu³⁺ co-dopan can reduce the trap depth of the title phosphor to obtain suitable ones.

Abstract: A novel unsymmetrical photochromic diarylethene compound bearing dithiol-pentane unit, 1-[2-methyl-5-(1,3-dithiol-pentane)-3-thienyl]-2-[2-methyl-3-benzofuran-yl]perfluoroyclopentene(1a) has been synthesized, and its photochromic, fluorescence and optical recording strorage properties were investigated. The compound exhibited remarkable photochromism and clear fluorescent switches both in solution and in PMMA film. Using diarylethene 1b/PMMA film as recording medium and a linearly polarized 650 nm laser diode for recording and readout, polarization multiplexed image recording can be carried out in this film. The results demonstrated that the diarylethene can be potentially used as polarization multiplexing holographic recording medium.

Abstract: Catalytic decomposition of acetylene was carried out at 400 °C using iron supported on sodium chloride as catalyst and the product was heat-treated at 650 °C under an argon atmosphere for 2 h directly. The sample was examined by scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction. The results show that nano onion-like fullerenes encapsulating Fe cores with diameters in the range 20-50 nm were obtained.

Abstract: Based on the basic principle of carbothermal reduction reactions in the ZrO2-C system, nanosized ZrC powders were synthesized by the preceramic method using Polyzirconoxane (PZO) and salicyl alcohol (SA) as sources of zirconia and carbon respectively. The obtained polymeric precursor exhibited excellent solubility and rheology for the processing of ceramic matrix composites. Thermal dynamic change process, phase composition, crystallite size and morphology of the synthesized powders were characterized by Thermogravimetric analysis (TGA)、 Scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). When heat-treated at 900 °C under flowing argon, precursors transformed into intimately mixed amorphous carbon and nanosized tetragonal ZrO2. Further heat treatments (1300 °C) led to the formation of zirconium carbide with a yield of 70.6 %. The obtained ZrC particles exhibit cubic morphology with size ranged in 50-100 nm. This study displays the preparation of nanosized ZrC materials from the preceramic polymers.

Abstract: An organic octupolar molecule with active hydroxyl groups was designed and synthesized. The structure and propertie of the organic molecule was characterized by IR,1H MNR, UV-vis and DSC-TG. The maximum absorption wavelength of the compound is 439 nm. The critical wavelength is below 710 nm. The compound is thermally stable with the decomposition temperature of 401°C, and consequently could be considered to be a better choice for the preparation of NLO material.

Abstract: A new photochromic diarylethene compound [1-(2-methyl-1-naphthyl), 2-(2-methyl-5-(4-dioxolanephenyl)-3-thienyl)]perfluorocyclopentene 1o was synthesized and its photochromic properties, fluorescence switch and kinetic properties were investigated in detail. Upon irradiated UV light it changes from colorless to red both in solution and in PMMA amorphous film. In addition, the kinetic experiment indicated that the cyclization/cycloreversion process belong to zeroth and first order reactions, respectively. Finally, the fluorescence spectrum of diarylethene 1o was decreased remarkable along with the cyclization reactions.

Abstract: A novel unsymmetrical diarylethene derivative 1-[2-methyl-5-(3-trifluoromethylphenyl)-3-thienyl]-2-[2-methyl-5-(4-hydroxylphenyl)-3-thienyl]hexafluorocyclopentene (1a) was successfully synthesized. The properties of the compound, including photochromic and fluorescence properties of the diarylethene were also investigated systematically. The results showed that this compound exhibited reversible photochromism, undergoing reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in solution and in PMMA film, and its absorption maxima were observed at 593 nm in methanol and at 598 nm in PMMA amorphous film, respectively, upon irradiation with 297 nm UV light. In methanol solution, the open-ring isomer of the diarylethene 1 exhibited relatively fluorescence at 569 nm when excited at 360 nm.

Abstract: A new photochromic diarylethene bearing an isoxazole unit has been synthesized, namely {1-(3,5-dimethyl-4-isoxazolyl), 2-[2-methyl-5-(3-methoxyphenyl)-3-thienyl]}perfluorocyclopentene. Its properties, including photochromic reactivity both in solution and in PMMA film, photoconversion ratio at photostationary state, fluorescence and optical recording property were investigated. It underwent reversible cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in hexane and in PMMA. The isomeric compound also functioned as a fluorescence switch by photoirradiation. Using this dithienylethene as optical storage was performed successfully.