Synthesis and optical properties of rhodamine terminated organosilicon dendrimers

Here we report on the synthesis of a series of branched organosilicon compounds bearing 2, 4, 6, 8, 12, 16 and 24 rhodamine 6G groups using the click conjugation strategy. Divinyldimethylsilane, tetravinylsilane, octavinylsilsesquioxane and vinyl terminated dendrimers on their basis were used as scaffolds to hold conjugated dye molecules. Obtained compounds were characterized by physical and photophysical methods and the change in the optical properties in the series was analyzed as a function of their functionalization. It was shown that absorption cross section of conjugated chmmophores inversely depends on their local concentration (i.e. molecule functionalization), while the fluorescence intensity in the series is the same for all compounds starting from 4functionalized and depends only on dendrimer concentration. On the basis of experimental data, theoretical calculations and literature, we hypothesized that PET and PDT mechanisms are responsible for fluorescence quenching.

Automated summary

In this study, a series of branched organosilicon compounds with varying numbers of rhodamine 6G groups were synthesized using the click conjugation strategy. Physical and photophysical methods were used to characterize the compounds and it was found that the absorption cross section of conjugated chromophores is inversely related to their local concentration, while fluorescence intensity is dependent on dendrimer concentration. The fluorescence quenching mechanisms were hypothesized to be PET and PDT based on experimental data, theoretical calculations, and literature review.