Two compounds with the formulas of Na(4)Cu(32)Sn(12)S(48 center dot)4H(2)O and K11Cu32Sn12S48 center dot 4H(2)O were synthesized via flux (with thiourea as reactive flux) and hydrothermal method, respectively. The black crystals of Na4Cu32Sn12S48 center dot 4H(2)O and K11Cu32Sn12S48 center dot 4H(2)O both crystallize in the cubic space group of Fm (3) over barc with the cell constants a = 17.921(2) angstrom and a = 18.0559(6) angstrom, respectively. The crystal structures feature a 3D open-framework with the unique [Cu8Sn6S24](z-) (z = 13 for Na4Cu32Sn12S48 center dot 4H(2)O; z = 14.75 for K11Cu32Sn12S48 center dot 4H(2)O) clusters acting as building blocks. The [Cu8Sn6S24](z-) cluster of the Th symmetry is built up by eight [CuS3] triangles and six [SnS4] tetrahedra. The powder samples were investigated by X-ray diffraction and optical absorption measurements. Both phase-pure compounds show multiabsorption character with a main absorption edge (2.0 eV for Na4Cu32Sn12S48 center dot 4H(2)O and 1.9 eV for K11Cu32Sn12S48 center dot 4H(2)O) and an additional absorption peak (1.61 eV for Na4Cu32Sn12S48 center dot 4H(2)O and 1.52 eV for K11Cu32Sn12S48 center dot 4H(2)O), which are perfectly consistent with the first-principle calculation results. The analyses of the density of states further reveal that the two optical absorption bands in each compound are attributed to the two transitions of Cu-3d-S-3p -> Sn-5s. The multiband nature of two compounds also enhances photocatalytic activity under visible light irradiation, with which the degradation of methyl blue over Na4Cu32Sn12S48 center dot 4H(2)O reached 100% in 3 h. The 3D open-framework features also facilitate the ionic conductivity nature of the Na4Cu32Sn12S48 center dot 4H(2)O compound, which achieved similar to 10(-5) S/cm at room temperature.