Organic–Inorganic Azafullerene‐Gold C59N‐Au Nanohybrid: Synthesis,Characterization, and Properties

Azafullerene (C₅₉N) was functionalized using a Mannich‐type reaction and then subsequently condensed with lipoic acid to yield dithiolane‐modified C₅₉N. In the following step, the extended dithiolane moiety from the C₅₉N core was utilized to decorate the azafullerene sphere with gold nanoparticles (Au NPs). The latter were initially stabilized with dodecanothiol (DT ? Au) and then integrated on azafullerene through a ligand exchange reaction with the dithiolane‐functionalized C₅₉N to produce the C₅₉N/DT ? Au nanohybrid. The nanohybrid was fully characterized by spectroscopy and microscopy, revealing the formation of spherical nanoparticles with a diameter in the range of 2–5 nm, as imaged by HR‐TEM. In the electronic absorption spectrum of C₅₉N/DT ? Au nanohybrid, the characteristic surface plasmon band (SPB) of Au NPs was observed, however, it was redshifted compared with that of DT ? Au. The redshift of the SPB is indicative of closer interparticle proximity of Au NPs, in accordance with the formation of aggregated NPs as observed by TEM, in C₅₉N/DT ? Au nanohybrid. Excited‐state interactions in C₅₉N/DT ? Au were probed by photoluminescence assays. It was found that the weak emission of C₅₉N at 819 nm was blueshifted by 14 nm in C₅₉N/DT ? Au, but was stronger in intensity, thus suggesting energy transfer to C₅₉N, within the organic–inorganic C₅₉N/DT ? Au nanohybrid. Finally, with the aid of pump–probe measurements and transient absorption spectroscopy, the formation of the singlet excited state of C₅₉N was identified.