Synthesis, crystal structure and photoluminescence of a novel tetra-nuclear calcium complex [{Ca(C15H8O7S)-(H2O)(DMSO)}3 {Ca(C15H8O7S) (DMSO)2}]�4DMSO

Abstract

The sulfonate derivate of chrysin coordinates with Ca 2+ to form a novel tetra-nuclear calcium complex [{Ca(C 15 H 8 O 7 S)(H 2 O)(DMSO)} 3 {Ca(C 15 H 8 O 7 S)(DMSO) 2 }]·4DMSO. The structure of the complex is characterized by IR, 1 H NMR and X-ray single-crystal diffraction analysis. The results show that the complex crystallizes in triclinic, space group Pī, cell parameter a = 1.4725(6) nm, b = 1.6480(7) nm, c = 2.1006(8) nm, α = 83.928(7)o, β = 85.938(7)o, γ = 85.212(7)o, V = 5.041(3) nm 3 , Dc = 1.476 g/cm 3 , Z = 2, m =0.568 nm −1 , F (000) = 2324, R = 0.0778, wR = 0.1821. In the complex, four Ca 2+ which are bridged by four 5-hydroxyanion-7-dihydro-xyflavone-6-sulfonate ligands with their carbonyl and 5-hydroxyanion group build an approximate square. The coordination number of Ca 2+ is 7 and the coordinated atoms are all oxygen from the carbonyl, hydroxyl and suflo-group of 5-hydroxyanion-7-hydroxyflavone-6-sulfonate, H 2 O and DMSO. Four ligands locate on two sides of the square. Two of them on the same side are almost paralleled and aromatic π-π stacking exists between them. Ligands on the opposite side are nearly perpendicular to each other. Meanwhile, the solid of title compound has the photoluminescent phenomenon. The title compound emits green fluorescence ( λ em = 520 nm) when it is excited at the wavelength of 410 nm and its photoluminescent mechanism is discussed.