Theoretical and NMR structural characterisation of a polymorphic azo dye

Protonand carbon-13NMRstudies in solution andcarbon-13CP-MASNMRin the solid state of apolymorphic azodye derived from2-amino- 5-nitrothiazole were performed and the results are discussed and compared with theoretical data from quantum chemical calculations. The polymorphism of this compound has conformational character, two conformers coexist in CDCl3 solution and in solid state, as shown by NMR. q2004 Elsevier B.V. All rights reserved