1-(2-Hy­droxy­eth­yl)-4-{3-[(E)-2-(trifluoro­meth­yl)-9H-thioxanthen-9-yl­idene]prop­yl}piperazine-1,4-diium bis­(3-carb­oxy­prop-2-enoate)

In the title salt, C(23)H(27)F(3)N(2)OS(+)·2C(4)H(3)O(4) (−), a non-merohedral twin [ratio of the twin components = 0.402 (1):0.598 (1)], the –CF(3) group is disordered over two sets of sites with occupancy factors in the ratio 0.873 (2):0.127 (2). The dihedral angle between the two outer aromatic rings of the 9H-thioxanthene unit, whose thio­pyran ring has a screw-boat conformation, is 33.01 (9)°. The diprotonated piperazine ring adopts a chair conformation. In the crystal, inter­molecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds between neighboring mol­ecules form zigzag chains along the a axis and contribute to the stabilization of the packing.