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

Three conformational polymorphs of 2-(1,4-dihydro-1,4-dioxonaphthalen-3-ylthio)
benzoic acid (L), an acetonitrile solvate of L, and cocrystal of L with 2,2′-bipyridine are
structurally characterized. The two polymorphs I and II have Z′ = 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 III has Z′ = 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 1 has Z′ = 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.