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

Abstract An expanded dinuclear copper(II) complex ( 1 ) derived from a biphenyl‐based hexaazamacrocyle L was synthesized and characterized by single crystal X‐ray analysis, exhibiting boat‐shaped cavity with an elongated Cu II ⋅⋅⋅Cu distance of 11.01 Å. The investigated for verity biologically relevant anions including carboxylates (oxalate, citrate, tartrate, glutamate, adipate, acetate benzoate), oxoanions (phosphate, sulphate, perchlorate nitrate), halides (fluoride, chloride, bromide iodide) competitive fluorescence titrations via indicator displacement assay (IDA) using external dye (Eosin Y) in water‐methanol solution at neutral pH. receptor shown to exhibit strong affinity oxalate, providing the binding trend: oxalate (log K =6.07)>citrate =5.74)>phosphate =5.02)>tartrate =4.78)>glutamate =4.42)>adipate =4.31)>acetate =4.14)>benzoate =4.01). No interaction observed other perchlorate, nitrate, fluoride, iodide under identical conditions.