4-Nitro-N-phthalyl-l-tryptophan

The crystal structure of the title compound [systematic name: (2R)-3-(1H-indol-3-yl)-2-(4-nitro-1,3-dioxoisoindolin-2-yl)propanoic acid], C(19)H(13)N(3)O(6), an analogue of epigenetic modulator RG108, is constrained by strong hydrogen bonds between the indole N—H group and a carbonyl O atom of the phthalimide ring of a symmetry-related mol­ecule, and between the protonated O atom of the carboxyl group and a carbonyl O atom of the phthalimide ring. π–π stacking inter­actions with centroid–centroid distances of 3.638 (1) and 3.610 (1) Å are also observed between indole and phthalimide rings.