Polymorphs and Solvates of 2-(1,4-Dihydro-1,4-dioxonaphthalen-3-ylthio)benzoic Acid

Abstract

Three conformational polymorphs of 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio) benzoic acid (<b>L</b>), an acetonitrile solvate of <b>L</b>, and cocrystal of <b>L</b> with 2,2′-bipyridine are structurally characterized. The two polymorphs <b>I</b> and <b>II</b> have <i>Z</i>′ = 1 and possess R₂²(8) type of dimeric structure in which the two aromatic rings are in trans disposition across the cyclic hydrogen bonded motifs. However, the dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone rings are −129.38° and 126.56°, respectively. The polymorph <b>III</b> has <i>Z</i>′ = 2; it shows R₂²(8) type of dimeric structures which are formed by two symmetry independent molecules. In its crystal lattice, the aromatic rings across the cyclic hydrogen bond motifs are in cis dispositions. Dihedral angles between the aromatic ring and 2-methyl 1,4-naphthoquinone ring in the two symmetry independent molecules are 114.82° and 125.27°, respectively. The acetonitrile solvate of <b>1</b> has <i>Z</i>′ = 3. In its crystal lattice, it has two symmetry independent molecules forming R₂²(8) hydrogen bonds to form dimeric assemblies and another cyclic R₂²(8) type hydrogen bond geometry between molecules which constitute the third set of symmetry independent molecules. The 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio)­benzoic acid also forms a 2:1 cocrystal with 2,2′-bipyridine; in this cocrystal the two nitrogen atoms are trans to each other and they participate in hydrogen bonds with carboxylic acids