A theoretical and spectroscopic (NMR and IR) study of indirubin in solution and in the solid state

The infrared spectrum of indirubin in the solid state and the 1 H, 13 C and 15 N NMR spectra in DMSO‐ d 6 solution as well as the 13 C and 15 N CPMAS spectra have been recorded. Different types of calculations (B3LYP, GIAO, and GIPAW) have been carried out. Experimental and calculated values were compared yielding commensurate results. E / Z isomerism was explored, as was oxo/hydroxy tautomerism.