Cadmium(II) Complexes with a Bulky Anthracene-based Carboxylate Ligand: Syntheses, Crystal Structures, and Luminescent Properties

To explore the coordination possibilities of anthracene-based ligands, three cadmium(II) complexes with anthracene-9-carboxylate (L) and relevant auxiliary chelating or bridging ligands were synthesized and characterized: Cd-2(L)(4)(2bpy)(2)(mu-H2O) (1), Cd-2(L)(4)(phen)(2)(mu-H2O) (2), and {[Cd-3(L)(6)(4bpy)])(infinity) (3) (2bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and 4bpy = 4,4'-bipyridine). Structural analyses show that complexes I and 2 both take dinuclear structures by incorporating the chelating 2bpy or phen ligand, which are further interlinked by intermolecular hydrogen-bonding, pi...pi stacking, and/or C-H...pi supramolecular interactions to generate higher-dimensional supramolecular frameworks. Complex 3 has a one-dimensional (ID) ribbon-like structure, which is further assembled into a two-dimensional (2D) layer, and a three-dimensional (3D) framework by the co-effects of interchain C-H...O hydrogen-bonding and C-H...pi supramolecular interactions. Moreover, the luminescent properties of these complexes were further investigated in detail.