A pentafluorophenyl functionalized RuII-probe having halogen bond center toward recognition and sensing of perrhenate and dihydrogen phosphate

Abstract

A newly designed Ru(II) probe, C1 containing iodotriazole (halogen bond unit) and pendent pentafluorophenyl (π-acidic) moiety shows superior dihydrogen phosphate sensing property over perrhenate and other inorganic anions. A supramolecular polymeric chain formation by the probe through halogen bond and anion-π interactions with dihydrogen phosphate is established by solid-state structural studies. On the contrary, C1 forms a dimeric aggregation via halogen bonding interaction with perrhenate. Macroscopic investigations, such as DLS, TEM, and SEM also show the formation of supramolecular polymeric aggregated structures with phosphates, however, such aggregation is not observed in the case of perrhenate. Polymeric aggregation of C1 with phosphate is additionally supported by DOSY NMR spectroscopy. Thus, the combined cooperative action of anti-electrostatic anion–anion (phosphate-phosphate), anion-π (phosphate-π of C6F5) and halogen-bonding (phosphate and C-I of probe C1) interactions are responsible for dihydrogen phosphate induced supramolecular polymeric aggregation. Finally, the formation of larger supramolecular self-assembly in presence of dihydrogen phosphate leads to selective sensing and higher binding towards the ion over perrhenate and other inorganic anions.