Molecular Recognition of Biologically Relevant Anions with an Expanded Dinuclear Copper(II) Complex: An Efficient Sensor for Oxalate Anion in Aqueous Solution

A dinuclear copper(II) complex derived from a biphenyl-based hexaazamacrocycle was synthesized and characterized crystallographically that exhibited strong affinity for oxalate over a variety of biologically relevant anions, showing the binding trend as oxalate>citrate>phosphate>tartrate>glutamate>adipate>acetate>benzoate, as investigated by competitive fluorescence titrations via indicator displacement assay using an external dye (Eosin Y) in water-methanol at neutral pH.