A water-stable molecular cadmium phosphonate bearing 2-(2-pyridyl)benzimidazole as a highly sensitive luminescence sensor for the selective detection of bisphenol AF and bisphenol B

Abstract

A dinuclear molecular cadmium phosphonate, [Cd₂(H₄tpmm)₂(Hpybim)₂(H₂O)₄]·2H₂O (1·2H₂O), emitting strong luminescence in both solid-state and suspension phases was synthesized by the reaction of Cd(ClO₄)₂, 2,4,6-tris(phosphorylmethyl)mesitylene (H₆tpmm), and 2-(2-pyridyl)benzimidazole (Hpybim) via the slow diffusion of reactants. Complex 1·2H₂O showed very poor solubility but high chemical stability in common organic solvents and H₂O. Furthermore, 1·2H₂O also revealed good thermal stability upon heating to 325 °C. Luminescence detection on a series of phenolic analytes within 5 min response time showed that bisphenol AF (BPAF) and bisphenol B (BPB) significantly reduced the luminescence intensity of 1·2H₂O in water, with the quenching efficiencies of 77 and 71%, respectively, while bisphenol Z (BPZ) moderately quenched the luminescence of 1·2H₂O in water by 52%. The Stern–Volmer quenching constant, K_sv, and the limit of detection (LOD) were determined to be 1931 M⁻¹ and 12.8 μM for BPAF, 515 M⁻¹ and 14.6 μM for BPB, and 2269 M⁻¹ and 3.0 μM for BPZ. In addition, 1·2H₂O behaving as a luminescence sensor has an exclusive detection for BPAF, BPB, and BPZ over a wide range of interfering phenolic analytes, with the exception of dopamine toward BPB. This work demonstrates a highly water-stable molecular cadmium phosphonate suitable for the luminescence detection of bisphenols, endocrine-disrupting chemicals, especially BPAF and BPB, in water.