Functionalization of C60 with diphosphonate groups: a route to bone-vectored fullerenes

Abstract

A facile synthesis for derivatizing fullerenes with diphosphonate groups based on the Bingel reaction has been explored. Five different bisadduct isomers of C60 with tetraethyl methylenediphosphonate, CH2(PO3Et2)2, have been synthesized, separated and characterized by MALDI-TOF mass spectrometry and 31P{1H} and 13C NMR spectroscopy. Hydrolysis of the C60[C(PO3Et2)2]2 isomers generates water-soluble diphosphonic acids, C60[C(PO3H2)2]2 for future in vitro and in vivo studies in which mineralized bone tissue will be selectively targeted.