Crystal structures and Hirshfeld surface analyses of 6,8-dimeth­­oxy-3-methyl-1H-isochromen-1-one and 5-bromo-6,8-dimeth­­oxy-3-methyl-1H-isochromen-1-one chloro­form monosolvate

In the mol­ecule of 6,8-dimeth­oxy-3-methyl-1H-isochromen-1-one, C12H12O4, (I), the two meth­oxy groups are directed anti with respect to each other. In the mol­ecule of the brom­inated derivative, 5-bromo-6,8-dimeth­oxy-3-methyl-1H-isochromen-1-one, that crystallized as a chloro­form monosolvate, C12H11BrO4·CHCl3, (II·CHCl3), the meth­oxy groups are directed syn to each other. In the crystal of I, mol­ecules are linked by bifurcated C—H⋯O hydrogen bonds, forming chains along the c-axis direction. The chains are linked by C—H⋯π inter­actions, forming a supra­molecular framework. In the crystal of II·CHCl3, mol­ecules are linked by C—H⋯O hydrogen bonds forming 21 helices parallel to the b-axis direction. The chloro­form solvate mol­ecules are linked to the helices by C—H⋯O(carbon­yl) hydrogen bonds. The helices stack up the c-axis direction and are linked by offset π–π inter­actions [inter­centroid distance = 3.517 (3) Å], forming layers parallel to the (100) plane. Compound II·CHCl3 was refined as a two-component twin. Two chlorine atoms of the chloro­form solvate are disordered over two positions and were refined with a fixed occupancy ratio of 0.5:0.5.