For the first time, the scope of Fisher esterification has been extended to fullerene derivatives to improve the synthesis of alkyne-functionalized fullerenes (fullerynes) using 1-chloronaphthalene as a solvent and a specially-designed, home-made reactor to promote high yield. The design allows for higher solubility of fullerene derivatives and a continuous azeotropic distillation for the removal of water to drive the reaction to completion with yields >90%. Both fullerynes (Fulleryne01 and Fulleryne02) were found to "click" to polymers, such as azide-functionalized poly(ε- caprolactone) (PCL-N3), in high efficiency without the need for fractionation. As evidenced by 1H NMR, 13C NMR, size exclusion chromatography, and matrix assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, the fullerene polymers thus obtained possess well-defined structure, narrow polydispersity (~1.01 by MALDI-TOF mass spectrometry; ~1.03 by size exclusion chromatography), and high fullerene functionality (~100%). They can serve as model compounds for the investigations of polymer structures and dynamics.
- Click chemistry
- Fisher esterification