Carbon Nanodots: Supramolecular Electron Donor-Acceptor Hybrids Featuring Perylenediimides

We describe the formation of charge-transfer com- plexes that feature electron-donating carbon nanodots (CND) and electron-accepting perylenediimides (PDI). The function- alities of PDIs have been selected to complement those of CNDs in terms of electrostatic and p-stacking interactions based on oppositely charged ionic head groups and extended p-systems, respectively. Importantly, the contributions from electrostatic interactions were confirmed in reference experi- ments, in which stronger interactions were found for PDIs that feature positively rather than negatively charged head groups. The electronic interactions between the components in the ground and excited state were characterized in complementary absorption and fluorescence titration assays that suggest charge-transfer interactions in both states with binding con- stants on the order of 8 � 10 4 m 1 (25 L g 1 ). Selective excitation of the two components in ultrafast pump probe experiments gave a 210 ps lived charge-separated state.