9-O-Ethyl-berberrubinium iodide monohydrate.

9-eth-oxy-10-meth-oxy-5,6-dihydro-1,3-dioxolo[4,5-g]isoquinolino-[3,2-a]isoquin-olin-7-ium iodide monohydrate), 2C(21)H(20)NO(4) (+)·2I(-)·H(2)O, two independent mol-ecules pack in the unit cell, where interactions between the molecules are stabilized by weak inter-molecular π-π stacking inter-actions [centroid-centroid distances in the range 3.571 (4) to 3.815 (4)Å]. Inter-molecular C-H⋯O inter-actions are also observed. The iodide anions are disordered with occupancy ratios of 0.94 (1):0.06 (1) and 0.91 (1):0.09 (1). The cationic molecule is planar in structure with a small torsion resulting from the dihydropyridine ring.