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[PF 6 ] 2 , of substituted pyridyl‐1,2,3‐triazole ligand ( L1 ) has been developed for the photoluminescence(PL) detection of phosphate (HP 2 O 7 3− /PPi) and Ag + ion in distilled CH 3 CN and mixed aqueous buffer (carbonate‐bicarbonate buffer/CH 3 CN; v/v, 9.5 : 0.5; 0.1 M; pH 10.6) at two different wavelengths, respectively. The multianalyte probe, 1[PF 6 ] 2 showed significant PL enhancement in the presence of H 2 PO 4 − , PPi, and Ag + with low detection limits of 0.48 μM, 0.43 μM, and 0.46 μM, respectively. The PL enhancement with phosphate ions is due to the triazole C−H⋅⋅⋅anion H‐bonding interaction that has been supported by 1 H NMR titration (for PPi) and single‐crystal X‐ray structure (for H 2 PO 4 − ). 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 σ ‐donor as well as π ‐donor. Consequently, the 3 MLCT‐ 3 MC energy gap is increased and the 1 ‐Ag emits efficiently from the 3 MLCT state. The probe also shows low cytotoxicity against Hela cells and is used for intracellular Ag + imaging.