Advanced Materials Research Vol. 952

Abstract: A new photochromic diarylethene compound 1-(1,2-dimethyl-7-azaindole-3-yl)-2-[2-methyl-5-(4-chlorphenyl)-3-thienyl] perfluorocyclopentene (1o) was synthesized, which properties were systematacially studied. The results showed that its absorption maxima were observed at 583 nm in hexane and at 597 nm in a PMMA film, respectively, upon irradiation with 297 nm UV light. Moreover, the diarylethene showed a remarkable fluorescence switches upon irradiation with UV and visible light.

Abstract: A new unsymmetrical photochromic diarylethene 1-[2-methyl-5-(1,3-difluorophenyl)-3-thienyl]-2-[2-methyl-5-(4-methoxylphenyl)-3-thienyl] perfluorocyclopentene has been synthesized,which a methoxyl group was substituted at the para-positions of the terminal phenyl ring. The photochromism of this compound was investigated, the results showed that this compound exhibited reversible photochromism, inducing cyclization and cycloreversion reactions upon alternating irradiation with UV and visible light both in solution and in a PMMA film. When irradiated 297 nm UV light, in hexane solution the maximum absorption was observed at 289 nm and 588 nm in opening-ring form and in close-ring form, respectively.

Abstract: A new unsymmetrical photochromic diarylethene, 1-[2,4-dimethyl-5-thiazolyl]-2-[2-methyl-5-(3-4-trifluoromethylphenyl)-3-thienyl] perfluorocyclopentene (1o) was synthesized, and its properties, such as photochromism in solution as well as in poly-methylmethacrylate (PMMA) amorphous film, and fluorescence properties were investigated in detail. The results showed the compound exhibited good photochromism in hexane solution and in PMMA amorphous film, the maxima absorption of its closed-ring isomer 1c are 490 nm and 495 nm respectively. The open-ring isomer of the diarylethene 1o exhibited relatively strong fluorescence at 449 nm in hexane solution (2 × 10^-5 mol/L) when excited at 330 nm and at 438 nm in PMMA amorphous film when excited at 280 nm. The fluorescence intensity decreased along with the photochromism upon irradiation with 297 nm light.

Abstract: A new fluorescence switch molecule based on a photochromic diarylethene and a fluorene unit was designed and constructed successfully. The compound exhibited good photochromism in acetonitrile with alternating irradiation by UV/Vis light, and the maxima absorption of its closed-ring isomer (1b) are 565nm. The open-ring isomer of the diarylethene 1a exhibited relatively strong fluorescence at 420 nm when excited at 290 nm. Its fluorescence intensity decreased along with the photochromism from open-ring isomers to closed-ring isomers upon irradiation with 297 nm UV light.

Abstract: High Temperature Gas-cooled Reactor is one of the candidates for the next generation advanced nuclear energy systems. As high temperature gas cooled reactor neutron moderator, reflector and structural material, nuclear graphite is very important in the nuclear industry to assure the safe operation of the reactor. The oxide reactor of nuclear graphite will change its internal pore structure and properties, such as mechanics properties, thermodynamic performance, radiant resistance, and so on. In this study, graphite coated with carbon was prepared by liquid impregnation method. Infrared spectral radiometry (FTIR), scanning electron microscope (SEM) and thermal gravity analysis (TGA) methods were used to characterize the structure of the carbon-coated graphite. Neutron absorption test method was also used to test the resistance to radiation. The results show that when the heat treatment time was 6h with the heat treatment temperature was 500¡æ, the material had the best morphology and had the largest neutron adsorption area (4.63 mb). The results suggest that this carbon-coated graphite has very good application prospect in nuclear industry.

Abstract: A new unsymmetrical photochromic diarylethene compound, 1-(2-methyl-3-benzofuranyl)-2-[2-methyl-5-(2-methyl-6-pyridyl)-3-thienyl] perfluorocyclopentene (1o), was synthesized and its photochemical, fluorescence properties were investigated systematically both in solution and PMMA amorphous film. The photochromic reaction kinetics results indicated that the cyclization processes of 1o belong to the zeroth order reaction and the cycloreversion process belong to the first order reaction.

Abstract: A novel photochromic diarylethene 1a has been synthesized. Its photochemical properties, including photochromic behavior and kinetics, have been investigated in detail. The result indicated that the Diarylethene 1a changed the color from colorless to pink irradiation with 297 nm UV light, in which absorption maxima were observed at 548 nm in hexane. The photochromic reaction kinetics indicated that the cyclization processes of 1a belong to the zeroth order reaction and the cycloreversion process belong to the first order reaction. The back irradiation by appropriate wavelength visible light regenerated its open-ring isomers and recovered the original emission intensity.

Abstract: A new photochromic diarylethene based on a phenanthrene, which is named 1-[2-methyl-5-(10-phenanthrenyl)-3-thienyl]-2-[2-methyl-5-(4-formylphenyl)-3-thienyl] perfluorocyclopentene, was designed and constructed successfully. At the same time, its photochromic properties, kinetics and fluorescence switch were investigated in detail. The results indicated that its photochromic behaviors could be modulated by UV/Vis light, changing from colorless to blue in dichloromethane solution. What is more, the kinetic experiments illustrated that the cyclization/cycloreversion process of this compound was determined to be the zeroth/first reaction. Furthermore, the optical switch experiment illustrated that the diarylethene 1o functioned as a remarkable fluorescent switch.

Abstract: A new photochromic diarylethene based on a phenanthrene, which is named 1-{2-methyl-[5-(4-methylene-bromine) phenyl]-3-thienyl}-2-[2-methyl-5-(10-phenanthrenyl)-3-thienyl] perfluorocyclopentene 1o, was designed and constructed successfully. We used it to accomplished recording by optical storage technology as memory medium. And its properties have been discussed systematically, including photochromic both in dichloromethane solution and in PMMA film and kinetics experiments. The result indicated that its photochromic behaviors could be modulated by UV/Vis light, changing between colorless and blue in dichloromethane solution and in PMMA film, respectively. What is more, the kinetic experiments illustrated that the cyclization/cycloreversion process of this compound was determined to be the zeroth/first reaction. In addition, the results demonstrated that the unsymmetrical diarylethene compound 1o, which we had synthesized, had attractive properties for potential application in optical storage.

Abstract: The HMG GG-C₁₄ was prepared by pre-swelling guar gum hydrophobic modification in alcohol-aqueous solution, the optical reactive condition was determined by studying the respective influence of each condition on the performance of the resultant product, and the final product possessed an apparent viscosity of 19957mPa·s (the apparent viscosity of parent guar gum is 11764mPa·s) and a substituting degree of 0.93%. The Ft-IR spectra of GG and GG-C₁₄ indicate the hydrophobic long chain alkyl was successfully grafted onto guar gum.