A Monkey‐Saddle‐Shaped Nanographene Embedding a Dicyclohepta[ <i>cd</i> , <i>fg</i> ]‐ <i>as</i> ‐Indacene Core and Two Additional Heptagons, and Its Paddle‐Wheel Co‐Assembly With Fullerenes
W. Liu, Huimin Zhang, Tingting Zhang, Zhou Lu, Yvonne Wagenhäuser, F. Würthner, Chongwei Zhu
Abstract
ABSTRACT We present a novel nanographene 1 that embeds a dicyclohepta[ cd , fg ]‐ as ‐indacene ( DCH‐ as ‐I ) motif and two additional heptagons. This defective π‐skeleton was efficiently synthesized from the oligophenylene precursors via the Scholl reaction, affording four heptagons in one shot. The integration of DCH‐ as ‐I and heptagons endows 1 with excellent solubility, superior fluorescence emission, multiple reversible redox processes, and exceptional supramolecular behavior. X‐ray crystallographic analysis shows that 1 adopts a chiral monkey‐saddle‐shaped conformation and exists as a pair of enantiomers in the crystal lattice. The saddles of 1 stack through π–π overlap into slipped π‐dimers, which further assemble into linear arrays with ellipsoidal cavities that encapsulate chloroform molecules, forming clathrate‐like structures. The supramolecular co‐assembly of saddle 1 with C 60 was confirmed both in solution and crystal states. Single‐crystal structures unequivocally revealed an unprecedented 4:4 complex (C 60 ) 4 ⊂( 1 ) 4 , in which four saddles of identical configuration and four C 60 spheres are alternately arranged into a chiral paddle‐wheel structure. Two such complexes of opposite chirality further dimerize in a staggered fashion to form an aesthetically‐striking octameric nanocubular supramolecular architecture. This study offers profound insights into the joint influence of DCH‐ as ‐I and heptagonal defects on the topology, electronic structure, photophysical properties, and supramolecular assembly behavior of nanographenes.