The water soluble derivatives of daidzein, sodium 4',7-diethoxyisoflavone-3'-sulfonate (1), magnesium 4',7-diethoxyisoflavone-3'-sulfonate (2) and zinc 4',7-diethoxylisoflavone-3'-sulfonate (3) have been synthesized. 1 was characterized by 1 H NMR and IR spectra, 2 and 3 were determined by single-crystal X-Ray diffraction analysis. The molecular structural characteristic of 2 is similar to that of 3. Their molecular contents are [Mg(H 2 O)] 6 (X) 2 8.H 2 O and [Zn(H 2 O)] 6 (X) 2 .8H 2 O (X=C 1 9 H 1 7 O 4 SO 3 - ), respectively. Two isoflavone skeletons of them have two different conformations. Twelve H atoms of six coordinated water molecules form hydrogen bonds with four oxygen atoms of sulfo-groups of two isoflavone skeletons and eight oxygen atoms of eight lattice water molecules. In addition, the π-π stacking interaction exists between isoflavone skeletons in the crystal structure of 2 and 3, which together with many kinds of hydrogen bonds lead to supramolecular formation with a three-dimensional network structure.