Abstract
Three cocrystals of acridine with 2,7-dihydroxynaphthalene (Ia and Ib) in two different polymorphs and 1,5-dihydroxynaphthalene (II) have been synthesized and characterized by single crystal X-ray diffraction method. Two polymorphs of acridine, 2,7-dihydroxynaphthalene cocrystal crystallizes in same space group \(P\bar{1}\) with different unit-cell parameters. In (Ia) the O–H group form a syn-anti conformation whereas in (Ib) the O–H group form an anti-anti conformation leads to the polymorphic structure of acridine, 2,7-dihydroxynaphthalene. This study reveals that the influence of π⋯π and C–H⋯π interactions in the formation of one-, two-, and three-dimensional supramolecular frameworks when the classical hydrogen bonds such as O–H⋯N and C–H⋯O are limited to discrete motifs. The acridine molecules form continuous π⋯π stacking in the crystal structure of (Ia) and discrete π⋯π stacking in the crystal structure of (Ib) and (II). The conformational flexibility of the substituted hydroxy group has an influence in the supramolecular frameworks of the three-dimensional crystal structure. The intermolecular interaction energy calculation between the molecular pairs has been carried out to study the strength of the interaction and its dependence on the geometrical parameters.
