Benzidine/Quinoidal‐Benzidine‐Linked, Superbenzene‐Based π‐Conjugated Chiral Macrocycles and Cyclophanes

Abstract

Synthesis of fully conjugated cyclophanes containing large-size polycyclic aromatics is challenging.N ow,t hree benzidine-linked, hexa-peri-hexabenzocoronene (superbenzene)-based ortho-, para-, and meta-cyclophanes are synthesized through intermolecular Yamamoto coupling reaction of structurally pre-organized precursors.S ubsequent oxidative dehydrogenation gave the corresponding quinoidal benzidinelinked cyclophanes.Their geometries were confirmed by X-ray crystallographic analysis and their electronic properties were investigated by electronic absorption, cyclic voltammetry,a nd DFT calculations.T he quinoidal benzidine-linked cyclophanes show thermally populated paramagnetic activity with ar elatively large singlet-triplet energy gap.T wo enantiomers for the ortho-cyclophanes (1-NH and 1-N)w ere isolated and their chiral figure-of-eight macrocyclic structures were identified. The cage-like cyclophanes 2-NH and 3-NH with concave surface can selectively encapsulate fullerene C 70 .