Syntheses, Crystal Structures, and Properties of Four Coordination Compounds with Sulfonate-Naphthol Ligand

Four coordination compounds, [Zn(ndsp)(bipy)(2)(H2O)](2)center dot 2H(2)O (1), Mn(ndsp)(bipy)(2)(H2O)center dot H2O (2), Ni(ndsp)(bipy)(2)(H2O) (3), Mn(ndsp)(phen)(2)(H2O)center dot CH3CH2OH center dot 2H(2)O (4) (K(2)ndsp = 2-naphthol-6,8-disulfonic acid dipotassium salt, bipy = 2,2 '-bipyridine, phen = 1,10-phenanthroline), have been synthesized by hydrothermal methods and their structures characterized. Compound 1 features a dimer of two mononuclear structural units. Each Zn ion is six-coordinated by one sulfonate group monodentately, and two bipy molecules and one water molecule. Compounds 2-4 show mononuclear structures, where central metal ions possess same coordination environment as compound 1. However, the sulfonate groups attached at different positions of naphthol ligands are involved in the metal coordination in compounds 1-4. The products 1-4 demonstrate fluorescent emissions at 425, 473, 470, and 437 nm, respectively, in solid state, which can be attributed to the intraligand emission. In contrast to free K(2)Hndsp, the blue-shifts of fluorescence emissions of compounds 1-4 can be assigned to the charge transitions between ligands and metal ions.