Formation of Zwitterionic Fullerodendron Using a New DBN-Focal Dendron

A new poly(amidoamine) dendron having 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) at the focal point was synthesized. Interestingly, formation of zwitterionic fullerodendrons (λ(max) = 930 nm for C(60) and 795 nm for C(70)) were observed by Vis-NIR spectroscopy upon the reaction of C(60) or C(70) with the DBN-focal dendron. In particular, the C(70) anion was effectively stabilized by the site isolation effect of the dendritic wedge. The half-life of fullerodendron 12b having C(70) anion at the focal point reaches 7,345 min, which is 20 times longer than that of complex between C(60) and pristine DBN. Furthermore, in order to confirm the structure of the zwitterionic complex, fullerodendron 12a was reprecipitated from benzonitrile/1,2,4-trimethylbenzene, and was observed using IR spectroscopy and APPI-MS.