Isostructural Crystallization Behavior of Dihydroanthracene and Dihydroacridine

The
crystal packing motifs of acenes are usually built up by heringbone
C–H···π interactions; on the contrary, N-heteroacenes form C–H···N contacts.
In the case of dihydroazaacenes the molecular structure of a rigid
aromatic system is interrupted by a flexible part. The influence of
heterocyclic CH2/NH substitution on the crystallization
behavior and crystal packing of 9,10-dihydroacridine (DHAC) and 9,10-dihydroanthracene
(DHAN) as well as a 1:1 mixture of both compounds was investigated
by differential scanning calorimetry (DSC) measurements, hot stage
microscopy methods, and crystal structure determination.