Crystal structure of (E)-2,6-di-tert-butyl-4-{[2-(2,4-di-nitro-phen-yl)hydrazinylidene]meth-yl}phenol.

The essential part (including all the non-hydrogen atoms except two methyl carbons) of the mol-ecule of the title compound, C21H26N4O5, lies on a mirror plane, which bis-ects the t-butyl groups. The conformation of the C=N bond of this Schiff base compound is E, and there is an intra-molecular N-H⋯O hydrogen bond present, forming an S(6) ring motif. In the crystal, mol-ecules are linked via O-H⋯O hydrogen bonds, forming zigzag chains propagating along the a-axis direction. There are no other significant inter-molecular contacts present.