Crystal Structure and Photoluminescence of a Tetranuclear Cadmium Complex

Abstract

A novel tetranuclear cadmium complex ([{Cd(C15H8O7S)(H2O)(DMSO)}3{Cd(C15H8O7S)(H2O)2}]·3DMSO·H2O) was obtained by the self‐assembly of Cd(II) with 5,7‐dihydroxyflavone‐6‐sulfonate. The complex was characterized by 1H NMR, IR, elemental analysis and X‐ray single‐crystal diffraction studies. It crystallizes in triclinic, space group $ P {\bar 1} $. In the complex, the chelate atoms of Cd(II) are all from oxygen. Four Cd(II) are connected via the carbonyl and 5‐hydroxyanion of four ligands and form an approximate square. Four ligands locate at two sides of the square, and two of them at the same side are almost parallel and exist aromatic π‐π stacking. Ligands on the opposite side of the square are nearly perpendicular. The result of the luminescent studies indicated that the solid of the complex shwed photoluminescent properties because of a combination of coordination, hydrogen bonding and π‐π stacking interaction in the molecule structure. The complex emits green fluorescence (λem=496 nm) when it is excited at the wavelength of 440 nm.

Potassium Complexes of Quercetin-5′-Sulfonic Acid and Neutral O-Donor Ligands: Synthesis, Crystal Structure, Thermal Analysis, Spectroscopic Characterization and Physicochemical Properties

“…So far, several papers have reported the crystal structures of sulfonic derivatives of different flavonoids and their complexes with alkali and transition metals (Table 1) [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The pattern of cation-anion interactions in these complexes depends on the position of the substituted sulfonic group and on the metal cation.…”

“…Moreover, some cations prefer to coordinate water molecules and form mononuclear complexes. It should be noted that ligands in the known complexes are derivatives containing sulfonic groups in the positions 6 [21][22][23][24][25][26]28], 8 [17][18][19][20] and 5′ [27] of the flavonoid skeleton (Table 1). Until now, the structure of only one complex with potassium cation has been determined [19].…”