Crystal structure, NMR and theoretical investigations on 2-(o-hydroxy-anilino)-1,4-napthoquinone

Crystal structure, 1H NMR and cyclic voltammetric investigations of 2-(o-hydroxy-anilino)-1,4-napthoquinone (HAN), resulting from coupling of aminophenol with 2-hydroxy-1,4-napthoquinone, have been carried out. X-ray structure reveals that the HAN ligand crystallizes in orthorhombic space group Pca21 with Z = 4, forming a chain via inter-molecular O2⋯H1AO1 and C15H15⋯O3 interactions. Both 1H NMR and cyclic voltammetry experiments suggest the titled ligand is associated and exists as dimer in d6-DMSO while the monomer has been predicted in CDCl3 solution. Density functional calculations can be utilized to gauge the strength of hydrogen-bonded interactions from the 1H chemical shifts in the NMR spectra. Self-consistent reaction field (SCRF) calculations further support the inferences drawn from cyclic voltammetry experiments.