Hexaaqua-(5,7-dihydr-oxy-4-oxo-2-phenyl-4H-chromene-8-sulfonato)calcium(II) 5,7-dihydr-oxy-4-oxo-2-phenyl-4H-chromene-8-sulfonate trihydrate.

In the title compound, [Ca(C(15)H(9)O(7)S)(H(2)O)(6)](C(15)H(9)O(7)S)·3H(2)O, the Ca centre has a distorted deca-hedral geometry, coordinated by six O atoms from water mol-ecules and one sulfonate O atom. The crystal structure is stabilized by aromatic π-π inter-actions, with centroid-centroid distances of 3.765†(5) and 3.896†(5)†à between the phenyl ring and the benzene ring of the chromene unit of neighbouring mol-ecules. In addition, the stacked mol-ecules exhibit inter- and intra-molecular O-H⋯O hydrogen bonds, including the uncoordinated water mol-ecules.