Convenient synthesis and host–guest compounds of 9,9′(10H,10′H)-spirobiacridines

9,9′(10H,10′H)-Spirobiacridine and its 2-methoxy derivative were prepared from the corresponding diphenylamines and acridone in three steps. A nearly D2d molecular skeleton of the spiro compounds was confirmed by X-ray crystallographic analysis. The spirobiacridines can work as a new class of host compounds owing to their ability to form nearly rectangular hydrophobic cages in the crystal.