Luminescence Detection of Ag+ and Phosphate Ions by a Ruthenium(II) Complex-Based Multianalyte Probe: A Combined Spectroscopic, Crystallographic, and Theoretical Approach

A bis-heteroleptic Ru(II) complex, 1[PF6](2), of substituted pyridyl-1,2,3-triazole ligand (L1) has been developed for the photoluminescence(PL) detection of phosphate (HP2O73-/PPi) and Ag+ ion in distilled CH3CN and mixed aqueous buffer (carbonate-bicarbonate buffer/CH3CN; v/v, 9.5 : 0.5; 0.1 M; pH 10.6) at two different wavelengths, respectively. The multianalyte probe, 1[PF6](2) showed significant PL enhancement in the presence of H2PO4-, PPi, and Ag+ with low detection limits of 0.48 mu M, 0.43 mu M, and 0.46 mu M, respectively. The PL enhancement with phosphate ions is due to the triazole C-H...anion H-bonding interaction that has been supported by H-1 NMR titration (for PPi) and single-crystal X-ray structure (for H2PO4-). A unique Ag(I)-triazolide complex formation is responsible for the PL enhancement in Ag+ ion detection. Triplet state TDDFT calculations were carried out to explain the PL enhancement of 1 . PPi and 1-Ag adducts. In 1-Ag, the L1 ligand becomes a better sigma-donor as well as pi-donor. Consequently, the (MLCT)-M-3-(MC)-M-3 energy gap is increased and the 1-Ag emits efficiently from the (MLCT)-M-3 state. The probe also shows low cytotoxicity against Hela cells and is used for intracellular Ag+ imaging.

Automated summary

A bis-heteroleptic Ru(II) complex has been developed for the photoluminescence detection of phosphate and Ag+ ions in different solvents with significant PL enhancement. The PL enhancement is attributed to triazole C-H...anion H-bonding interaction for phosphate ions and unique Ag(I)-triazolide complex formation for Ag+ ion detection. Triplet state TDDFT calculations explain the PL enhancement and the probe also shows low cytotoxicity against Hela cells and can be used for intracellular Ag+ imaging.