Six novel pyrromethene- BF2 complexes,of which five compounds have not been reported,were synthesized and characterized.Their relationships between structure and photophysical behavior were studied with the aid of flu...Six novel pyrromethene- BF2 complexes,of which five compounds have not been reported,were synthesized and characterized.Their relationships between structure and photophysical behavior were studied with the aid of fluorescence and triplet state absorption spectra.The results indicate that,compared to 8- alkylpyrromethene- BF2 complexes,the compounds containing 8- aryl exhibit high fluorescence quantum yield and rather low triplet state absorption.展开更多
In the water-in-oil mieroemulsion system of Triton X-100, 1-hexanol, cyclohexane and Fe（NO3）3 aqueous solution, α－Fe2O3 ultrafine particles were prepared by the method of precipitation using NH3. From transndssion...In the water-in-oil mieroemulsion system of Triton X-100, 1-hexanol, cyclohexane and Fe（NO3）3 aqueous solution, α－Fe2O3 ultrafine particles were prepared by the method of precipitation using NH3. From transndssion electron ndcrographs the mean dianreter of particles is about 3nm. The trifornlity of particle is good. These result have been confirmed by the method of Mossbauer spectrum measurement. The conditions of preparation of α－Fe2O3 ultrallne particles could be controlled easily and the reaction medium could be used cyclically.展开更多
The precursor for nano-sized magnesia was prepared by using Mg(NO3)2·6H2O as raw material, the hydrolysis product of hexamethylene tetramine as precipitating reagent and water as reaction media, and with the poly...The precursor for nano-sized magnesia was prepared by using Mg(NO3)2·6H2O as raw material, the hydrolysis product of hexamethylene tetramine as precipitating reagent and water as reaction media, and with the polymer (PEG) and DMF as protection reagents for particles. Nano-sized magnesia was prepared by calcining the precursor at 873 K after being dehydrated by freeze centrifugation and vacuum drying at a constant temperature. The formation process and structure of MgO nanocrystallites were investigated by means of TG-DTA, FTIR, TEM, XRD and BET. The results showed that the crystal belonged to cubic system and the average size was 3.1 nm and the specific surface area was 229 m2·g-1.展开更多
文摘Six novel pyrromethene- BF2 complexes,of which five compounds have not been reported,were synthesized and characterized.Their relationships between structure and photophysical behavior were studied with the aid of fluorescence and triplet state absorption spectra.The results indicate that,compared to 8- alkylpyrromethene- BF2 complexes,the compounds containing 8- aryl exhibit high fluorescence quantum yield and rather low triplet state absorption.
文摘In the water-in-oil mieroemulsion system of Triton X-100, 1-hexanol, cyclohexane and Fe（NO3）3 aqueous solution, α－Fe2O3 ultrafine particles were prepared by the method of precipitation using NH3. From transndssion electron ndcrographs the mean dianreter of particles is about 3nm. The trifornlity of particle is good. These result have been confirmed by the method of Mossbauer spectrum measurement. The conditions of preparation of α－Fe2O3 ultrallne particles could be controlled easily and the reaction medium could be used cyclically.
文摘The precursor for nano-sized magnesia was prepared by using Mg(NO3)2·6H2O as raw material, the hydrolysis product of hexamethylene tetramine as precipitating reagent and water as reaction media, and with the polymer (PEG) and DMF as protection reagents for particles. Nano-sized magnesia was prepared by calcining the precursor at 873 K after being dehydrated by freeze centrifugation and vacuum drying at a constant temperature. The formation process and structure of MgO nanocrystallites were investigated by means of TG-DTA, FTIR, TEM, XRD and BET. The results showed that the crystal belonged to cubic system and the average size was 3.1 nm and the specific surface area was 229 m2·g-1.
