Porphyrin/carbon nanodot supramolecular complexes and their optical properties

The functionalization of carbon dots with dyes by exploiting supramolecular interactions represents a huge resource in nanomaterials science. Desired properties, and especially the optical ones, can be obtained starting from the knowledge of surface-related interactions, which can be exploited to originate the complex. In this context, the present work explores the photophysical properties of supramolecular complexes, spontaneously formed, in the water medium, by the interaction of the anionic meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS4) with three different fluorescent carbon nanodots (CNDs). The results of UV-vis, steady-state and timeresolved fluorescence experiments show that the formation of porphyrin/carbon dot adducts is favoured if nanodot surface charge is high enough to ensure electrostatic attraction of the porphyrin, and the resulting emission properties depend on the surface precursor as well. In such adducts, both species undergo fluorescence quenching through non-radiative mechanisms such as electron transfer, making these nanomaterials economic candidates for applications in energy conversion or sensor field.