Ultrafast relaxation processes of multi-branched compounds based on 1,3,5-triazine: An investigation of the causes of a high fluorescence quantum yield after modification with perfluoroalkyl chains

The effect of modifying a 1,3,5-triazine-based multi-branched compound (T03-a) with perfluoroalkyl chains (T03-d) on the fluorescence and ultrafast dynamics was investigated by two-photon fluorescence and femtosecond transient absorption experiments. After modification, a significantly increased fluorescence quantum yield was observed. The fluorescence quantum yield of the perfluoroalkyl chain modified compound T03-d (0.86) was approximately 3.2 times greater than that of T03-a (0.27). The ultrafast dynamics experiments revealed the effect of the perfluoroalkyl chain modification on the intramolecular charge transfer (ICT) property. The ultrafast dynamics results agree with the changes in the fluorescent property. Our results indicate that the modification of compounds with perfluoroalkyl chains based on the 1,3,5-triazine tri-branched compound would be a very useful strategy for enhancement of the fluorescence, and the 1,3,5-triazine based multi-branched derivatives have the potential to be employed as molecular probes for biological fluorescence imaging.