Amitriptylinium picrate: conformational disorder

In the structure of the title salt [systematic name: 3-(10,11-dihydro-5H-dibenzo[a,d][7]annulen-5-yl­idene)-N,N-dimethyl­propan-1-aminium 2,4,6-trinitro­phenolate] of a tricyclic anti­depressant, C20H24N+·C6H2N3O7−, the dimethyl­amino­propyl subunit possesses a classical static conformational disorder. The central cyclo­hepta­diene ring adopts a bent conformation that is inter­mediate between boat and chair forms, leading to a butterfly shape for the hetero-tricyclic moiety. In a complementary fashion, donors from amitriptyline and acceptors from picrate form inter­molecular C—H⋯O hydrogen bonds and N—H⋯O salt bridges. These hydrogen bonds cluster amitriptyline and picrate ions into a closed R44(36) hetero-tetra­mer, whereas inter­molecular C—H⋯π inter­actions between amitriptyline ions cluster them into homo-dimers. Significant π–π stacking inter­actions are also observed between aromatic rings of amitriptyline and picrate, and these, combined with the C—H⋯π inter­actions, associate mol­ecules into linear arrays along the [1[\overline{1}]1] direction