Nanographene Imides Featuring Dual-Core Sixfold [5]Helicenes

A novel kind of nanographene imide, namely pentaperylene decaimides (PPD) featuring dual-core sixfold [5]helicenes and ten imide groups, was efficiently obtained. Among the possible 28 stereoisomers, which include 14 pairs of enantiomers, only one pair of enantiomers was obtained selectively which could be separated by chiral HPLC. Single-crystal X-ray diffraction analyses revealed that it exhibits a D₂-symmetric “four-bladed propeller” conformation composed of conjoined double “three-bladed propeller”, which is very stable and could not convert into other conformations even when heated up to 200 °C. Meanwhile, enantiomerically pure PPD also exhibits an excellent resistance to thermally induced racemization, which makes it a promising candidate for various applications in chiral material science.