Crystal structure and DFT study of the zwitterionic form of 3-{()-1-[(4-ethoxyphenyl)iminiumyl]ethyl}-6-methyl-2-oxo-2-pyran-4-olate.

The title Schiff base compound, CHNO, crystallizes as a zwitterion, with the phenolic H atom having been transferred to the imino group. The resulting iminium and hy-droxy groups are linked by an intra-molecular N-H⋯O hydrogen bond, enclosing an (6) ring motif. The conformation about the C=N bond is and the dihedral angle between the benzene and pyran rings is 70.