title: Bis-heteroleptic ruthenium(II) complex of a triazole ligand as a selective probe for phosphates.
abstract: A new bis-heteroleptic ruthenium(II) complex (1) of 2-(1-methyl-1H-1,2,3-triazol-4-yl) pyridine (L) ligand was extensively explored for anion sensing studies. 1[PF6]2 shows selective sensing of dihydrogen phosphate (H2PO4(-))/hydrogen pyrophosphate (HP2O7(3-)) among halides, HCO3(-), AcO(-), NO3(-), ClO4(-), HSO4(-), OH(-), BzO(-), H2PO4(-), and HP2O7(3-) in acetonitrile. Enhancement of emission intensity of 1[PF6]2 along with a 10 nm red shift of the emission maximum is observed in the presence of H2PO4(-)/HP2O7(3-) selectively. The photoluminescence (PL) titration experiment of 1[PF6]2 results in binding constants (K(a)) of 5.28 × 10(4) M(-1) and 4.67 × 10(4) M(-1) for H2PO4(-) and HP2O7(3-), respectively, which is in good agreement with the Ka values obtained from UV-vis titration experiments (2.97 × 10(4) M(-1) and 2.45 × 10(4) M(-1) for H2PO4(-) and HP2O7(3-), respectively). High selectivity of 1[PF6]2 toward these two anions in acetonitrile is further confirmed by PL intensity measurement of 1[PF6]2 upon addition of these two anions in the presence of a large excess of other competitive anions. Further, considerable changes in the lifetime (τ) as well as in the decay pattern of 1[PF6]2 in the presence of H2PO4(-)/HP2O7(3-) among all tested anions support the selective binding property of 1[PF6]2 toward these two anions. Significant downfield shift of the triazole -CH proton of 1[PF6]2 with 1 equiv of H2PO4(-) (Δδ = 0.26 ppm) and HP2O7(3-) (Δδ = 0.23 ppm) in deuterated dimethyl sulfoxide proclaim binding mechanism via C-H···anion interaction in solution state. Finally, single-crystal X-ray structural analysis confirms the first example of dihydrogen pyrophosphate (H2P2O7(2-)) recognition via solitary C-H···anion interactions.
authors: Department of Inorganic Chemistry, Indian Association for the Cultivation of Science , 2A & 2B Raja S. C. Mullick Road, Kolkata 700032, India.
authors: Bijit
authors: B
authors: Chowdhury
authors: Snehadrinarayan
authors: S
authors: Khatua
authors: Ranjan
authors: R
authors: Dutta
authors: Sourav
authors: S
authors: Chakraborty
authors: Pradyut
authors: P
authors: Ghosh
mesh_terms: D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D012428:Ruthenium / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D014230:Triazoles / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D008024:Ligands; D009942:Organometallic Compounds; D010710:Phosphates; D014230:Triazoles; D012428:Ruthenium