Bis-Heteroleptic Ruthenium(II) Complex of Pendant Urea Functionalized Pyridyl Triazole and Phenathroline for Recognition, Sensing, and Extraction of Oxyanions

A new bis-hetorOleptic Ru-II complex based ditopic receptor, TIFF6](2), having an anion binding triazole CH unit and appended 4-fluotophenyl urea arm has been developed. H-1 NMR and isothermal titration calorimetry (ITC) experiments showed binding of 1[PF6](2) toward oxyanions such as phosphates (e.g., H2PO4-, and HP2O73-) and carboxylates CH3CO2- and C6H5CO2) anions selectively. NMR studies showed that. highly basic phosphate anions such as HP2O73-/H2PO4- are bound by both -CH and -NH units of -Complex 1[F-F-6](2). However, comparatively less basic CH3CO2-, C6H5CO2 anions interacted with the urea -NH protons only. Thermodynainic parameters obtained from ITC:oxperiments suggested that binding of all the- interacting anions with complex 1[PF6](2) are highly enthalpy and entropy -,driven processes. Importantly, complex 1[PF6]2 showed extraction of H2PO4-, CH3CO2-,.and C6H5CO2- anions from aqueous solution via liquid=liquid extraction with efficiencies of 28%, 74%, and 80%, respectively. The influential role of the urea moiety in the course of extraction is demonstrated by comparison with a model Complex, 2[PF6](2). Additionally, complex 1[PF6](2) is capable of selective sensing of phosphate anions among all investigated anions.