The mononuclear complex, Cu(H2SIP-O)(bpy)(H2O) (H4SIP-O = 4-hydroxyl-5-sulfoisophthalic acid and bpy = 2,2'-dipyridyl), has been synthesized by the hydrothermal reaction of Cu(OH)(2) with NaH2SIP and bpy at 160 degrees C, and characterized by single-crystal X-ray diffraction, elemental analysis and IR spectrum. The new ligand 4-hydroxyl-5-sulfoisophthalic acid derived from 5-sulfoisophthalic acid ligand under an in situ hydrothermal condition. The crystal of the complex crystallizes in a triclinic system, space group P (1) over bar, with a = 7.757(4), b = 10.663(6), c = 11.727(7) angstrom, alpha = 94.272(4), beta = 104.067(7), gamma = 97.400(7)degrees, V = 927.4(g) angstrom(3), Z = 2, C18H14N2O9SCu, M-r = 497.93, D-c= 1.783 g/cm(3), mu = 1.350 mm(-1), F(000) = 506, the final R = 0.0518 and wR = 0.1513 for 4180 observed reflections with I > 2 sigma(I). The central Cu(II) ion is five-coordinated by two oxygen atoms from the H2SIP-O2- ligand and two nitrogen atoms of bpy ligand in a distorted square-planar geometry as well as a water oxygen atom in the apical position to complete a distorted square-pyramidal coordination geometry. The mononuclear copper molecules are linked by hydrogen bonds between coordinated water molecules and sulfonate groups to form a one-dimensional double-chain structure. The chains are further held together through extensive pi-pi stacking interactions between the aromatic rings to form a three-dimensional supramolecular structure.
