Fullerene-Pyrrolidine Biferrocene Donor-Acceptor Triads: Synthesis and Effects of Fullerene[60] on the Electronic Communication of the Two Ferrocene Units in Biferrocene

摘要

A novel nanoscale molecule, fullerene[60]-based biferrocene (C-60-ph-Fc-Fc), was prepared via covalent grafting of biferrocene onto C-60 using 1,3-dipolar cycloaddition and was fully characterized by mass spectrometry, nuclear magnetic resonance spectroscopy, infrared spectroscopy, ultraviolet-visible spectroscopy, and fluorescence spectroscopy. Cyclic voltammetry studies showed that C-60-ph-Fc-Fc undergoes four successive quasi-reversible processes in the potential window of -2.0 similar to 0.40V (versus Fc(+)/Fc). The biferrocene (moiety) exhibited significant electronic communication between the two ferrocenyl groups both before and after grafting onto C-60. Grafting of fullerene led to weakening in the electronic interaction, and the comproportionation constant decreased by nearly five orders of magnitude from 1.56 x 10(6) for Fc-Fc to 88 for C-60-ph-Fc-Fc, indicating that the electronic communication between halves of the biferrocene could be effectively modified by grafting of C-60. The temperature-dependent magnetic susceptibility (2-300 K) study showed that there was a strong antiferromagnetic interaction between the ferrocene Fe-II centres.