Hexaquacobalt(II) bis(5-hydroxy-7-methoxy-4-oxo-2-phenyl-4H-chromene-6-sulfonate) tetrahydrate.

The title compound, [Co(H(2)O)(6)](C(16)H(11)O(7)S)(2) x 4 H(2)O, with cobalt(II) at the centre of symmetry, exhibits alternating hydrophilic and hydrophobic regions. Hydrophilic regions are generated by O-H...O hydrogen bonds among sulfonate groups, involving solvent water molecules and coordinated water molecules; pi-pi stacking interactions assemble the flavone skeletons into columns which form the hydrophobic regions. A three-dimensional network is built up from an extensive array of hydrogen bonds, pi-pi stacking interactions and electrostatic interactions between the cation and anion. As a salt of the sulfonated derivative of naturally occurring tectochrysin (5-hydroxy-7-methoxyflavone), this compound offers enhanced solubility and potential biological activity over the natural product.