Polymorphism in 1-(4-fluorophenyl)-3,6,6-trimethyl-2phenyl-1,5,6,7-tetrahydro-4H-indol-4-one:: A subtle interplay of weak intermolecular interactions

An understanding of structural features associated with polymorphism in an anti-implantation agent has been made in terms of morphology, single-crystal structure, powder X-ray diffraction, and differential scanning calorimetric measurements. Polymorph 1 (P1) crystallizes from a solution in dichloromethane/hexane in monoclinic, noncentro symmetric P2(1) (as plates), whereas the second polymorph (P2) crystallizes from a solution in EtOH/acetone in tetragonal, centro symmetric P4(2)/n (as blocks). P1 is stabilized by C-H---O and C-H---pi intermolecular interactions forming molecular chains, while P2 is stabilized by C-H---O and C-H---pi dimers and a not so common F---F intermolecular interaction.