Preparation And Study Of Rhodamine And Ramification Grafted In Nano-SiO₂

With the development of economic and technology, fluorescence dyes havebeen integrated into the series fields of production and human life. There aremany kinds of fluorescence dyes that have been studied and developed for along time. Nowadays, more increasing attentions have been paid to the materialswith good properties, low price and easy preparation. Because of the goodproperties, Nano-materials play an important role in the fields of optics,mechanics, thermal, electromagnetism and chemistry compared with bulkmatierials. As the member of nano-materials, mesoporous materials attractedmany attentions owing to their good characters containing larger surface area,highly ordered structure, high thermal stability, a variable pore size and goodadsorption capacity for organic molecules, so it has been used in many fieldssuch as adsorption, catalytic, host-guest materials, photoelectricity, medical andenvironment. Today, mesoporous materials have been used as a carrier forfluorescent materials.In this paper, rhodamine series has been choosed as the guest materialsbecause its good features including larger molar absorption coefficient, higherfluorescence quantum yield, longer wavelengths of absorption and emission,stable structure owing to the rigid coplanar structure, higher photostability andused silicon-based ordered materials (SBA-15and MCM-41) and SiO2particlesas the host of the composite. Loading fluorescence dyes into inorganic materialsaim at studying more new properties. The dyes have been almost broken apartinto single molecule and the size of molecule has been controlled by confinedspace effect. Rhodamine B has been embedded in SBA-15, MCM-41and solid SiO2with the method of modification and grafting. We investigated the differentfluorescent properties by changing the carrier of fluorescent materials. Theresults show that the flurescent dyes have been grafted into nano-materials andthe fluorescent emission of all the abtained materilals shifted to lowerwavelength after grafting (RhB/APTES/MCM-41shifted to415nm,RhB/APTES/SBA-15shifted to517nm, RhB/APTES/SiO2shifted to563nm)in comparison with that of pure luminescent dyes.The effect of loading amount of Rhodamine B on the fluorescenceproperties has been studied. The results show that the emission spectra have ablue shift with content increase of Rhodamine B (from510nm to506nm to504nm to501nm to501nm).Lissamine RhB has been embedded in SBA-15in the way of physicaladsorption. Fluorescent emission spectrum of the resulting materials shifted to alower wavelength in comparison with that of pure luminescent dyes (from584nm to555nm). The fluorescence intensity is weak due to instability of physicaladsorption.