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By using a flexible multicarboxylate ligand, 2,2′-(2-((2-carboxy-5-methylphenoxy)methyl)-2-(4-methylphenylsulfonamido)propane-1,3-diyl)bis(oxy)bis(4-methylbenzoic acid) (H3L), and two kinds of N-donor ligands, four new zinc(II) and cadmium (II) metal coordination complexes [Zn2(HL2−)2(phen)2]·2H2O (1), [Zn(HL2−)(4,4′-bpy)0.5(H2O)]n (2), [Cd(HL2−)(phen)(H2O)]n (3), and [Cd2(HL2−)2(4,4′-bpy)3]n·n(DMF·CH3OH·H2O) (4) (phen = 1,10-phenanthroline, and 4,4′-bpy = 4,4′-dipyridine) have been prepared under solvothermal conditions and structurally characterized by elemental analysis, FT-IR spectra, thermogravimetric analysis. The various topologies of the structures have been generated by adjusting the auxiliary N-donor ligand and the central metal ions. Complex 1 features a discrete neutral dinuclear cage structure, complex 2 displays a 1D ladder-like chain, complex 3 exhibits a 1D infinite zigzag chain, while complex 4 possesses a rare 5-connected 2D networks with the point symbol (48·62). These results indicate that both the metal center and the auxiliary N-donor ligand have significant influences on the structure of the final assembly. Moreover, the thermal stabilities and luminescent properties of 1–4 have also been investigated in detail.

A simple quinoline-based fluorescent probe L for Ag+ has been developed. Probe L shows fluorescence enhancement (turn on) response towards Ag+ with high selectivity in aqueous media (methanol–water, v/v = 3:7, pH 7.2, 20 mM Tris–HCl) based on a combinational effect of the inhibition of intermolecular photoinduced proton transfer and chelation-enhanced fluorescence. And an obvious fluorescent color change could be observed by naked eyes under the light of 365 nm. The binding mode between L and Ag+ has been found to be 1:1 based on the fluorescence/absorption titration, ESI-MS and further confirmed by X-ray crystallography.