Up-converted emission in a series of phenylazomethine dendrimers with a porphyrin core.

The nonlinear optical and time-resolved properties of a series of phenylazomethine-porphyrin dendrimers are reported. The linear optical properties were also investigated, and the efficiency of the energy transfer process was obtained. Measurements were also carried out with the basic building-block molecules. The process of frequency up-converted emission was observed in these porphyrin dendrimers. The mechanism for this effect is investigated and related to the process of "hot-band" absorption in the phenylazomethine-porphyrin system. Time-resolved measurements also suggested efficient intramolecular vibrational energy redistribution in these systems. These properties suggest that the porphyrin dendrimers may also have applications in light harvesting of low-frequency photons, as well as in sensors.