An integrated urea and halogen bond donor based receptor for superior and selective sensing of phosphates

Abstract

A new Ru^II based bis-heteroleptic ditopic receptor, 1[PF₆]₂ (C₄₄H₃₃F₁₂IN₁₀OP₂Ru), having integrated anion binding iodotriazole (halogen bond donor) and urea units (–NH bond donor) is employed for selective sensing of phosphates (e.g., H₂PO₄⁻ and HP₂O₇³⁻). 1[PF₆]₂ showed superiority in phosphate sensing in CH₃CN as compared to its hydrogen bond donor analogue, 2[PF₆]₂ (C₄₄H₃₄F₁₂N₁₀OP₂Ru), non-urea halogen bond analogue, 3[PF₆]₂ (C₃₈H₂₇F₁₂IN₈P₂Ru) and non-urea hydrogen bond donor analogue, 4[PF₆]₂ (C₃₈H₂₈F₁₂N₈P₂Ru) in terms of enhanced binding constant values, longer excited state lifetimes and lower detection limit values. ¹H-NMR, Isothermal Titration Calorimetry (ITC) and photophysical studies revealed the implementation of the combined role of both the halogen bond donor iodotriazole unit and the –NH unit of the urea moiety for selective and enhanced binding of phosphates.