2-(4-Methyl-phen-yl)-7-(2-methyl-prop-oxy)-4H-chromen-4-one-6-chloro-2-(4-methyl-phen-yl)-7-(2-methyl-prop-oxy)-4H-chromen-4-one (19/1).

The title co-crystal, 0.95C(20)H(20)O(3)·0.05C(20)H(19)ClO(3), arises as the chloride carried over during the synthesis shares a position with an aromatic H atom; the partial occupancies are 0.947 (2) and 0.053 (2) for H and Cl, respectively. The mol-ecular structure is stabilized by intra-molecular C-H⋯O contacts, forming pseudo five- and six-membered rings with S(5) and S(6) graph-set motifs, respectively. The crystal structure features π-π stacking inter-actions between the centroids of the central fused ring systems [centroid-centroid distance = 3.501 (2) Å].