Di(phenyl­propyl­amino)­gossypol: a derivative of the dimeric natural product gossypol

Di(phenyl­propyl­amino)­gossypol [systematic name: 2,2'-bis­{1,6-dihy­droxy-5-isopropyl-8-[(3-phenyl­propyl­amino)methyl­idene]naphthalen-7-one}, C₄₈H₅₂N₂O₆, was formed by reaction of the dimeric natural product gossypol with 3-phenyl­propyl­amine. The structure of this compound has its two naphthalene ring systems oriented approximately perpendicular to each other, and the two pendant phenyl­propyl groups have different conformations. One of these side groups is considerably disordered at room temperature but less so at 120 K. The enantio­meric mol­ecules form centrosymmetric dimers that are supported by inter­molecular hydrogen bonds and by hydro­phobic inter­actions between a pair of naphthalene rings. Two additional hydrogen bonds tie the dimer pairs into layers. Unlike gossypol and many gossypol Schiff base derivatives, the title compound crystallizes without the inclusion of solvent, which appears to occur because of the size and flexibility of its phenyl­propyl pendent groups.