2-Amino-4-(4-meth-oxy-phen-yl)-5-oxo-4 H ,5 H -pyrano[3,2- c ]chromene-3-carbo-nitrile acetic acid monosolvate.

In the title co-crystal, C 20 H 14 N 2 O 4 ·C 2 H 4 O 2 , the expected proton transfer from acetic acid to amine has not occurred. In the crystal, the chromene mol-ecules are linked by N-H⋯O and N-H⋯N hydrogen bonds to generate [100] columns. The acetic acid mol-ecules form inversion dimers linked by pairwise O-H⋯O hydrogen bonds and occupy voids between the columns.