Ruthenium(II) Complex-Based Luminescent Bifunctional Probe for Ag⁺ and Phosphate Ions: Ag⁺-Assisted Detection and Imaging of rRNA

Abstract

A new bis-heteroleptic Ru(II) complex (1) of benzimidazole-substituted 1,2,3-triazole pyridine ligand has been designed and constructed for the photoluminescent detection of cationic and anionic analytes, Ag and phosphate ions. Compound, 1[PF] was fully characterized by various spectroscopic techniques and the solid-state structure was determined via single-crystal X-ray diffraction. The cation and anion sensing properties in 50% aqueous buffer (pH 9.2) and pure acetonitrile were carefully examined in photoluminescence (PL) spectroscopy. The 1[PF] was found to be highly selective to pyrophosphate; PPi/HPO and HPO ions in CHCN. It showed ∼10-fold PL intensity enhancement at 583 nm in the presence of only 1 and 2 equiv of PPi and HPO ions, respectively. The PL titrations of 1[PF] with PPi and HPO in CHCN furnished the association constant (K = 3.3 × 10 M and 6.8 × 10 M) and the detection limit was as low as 5.73 and 5.19 ppb, respectively. The 1[PF] also selectively detected Ag over other competitive cations through the luminescence light up in 50% aqueous buffer (pH 9.2) media. The PL titration of 1[PF] with Ag showed ∼8-fold luminescence enhancement at 591 nm and yielded association constant, K = 3.5 × 10 M and the detection limit was determined to be 5.05 ppb. A new cation sensing mechanism has been established where the Ag ion is detected in photoluminescence spectroscopy through the unique cyclometalated Ag-triazolide complex formation. The high selectivity of 1[PF] for phosphates and Ag was established by PL in the presence of various competing ions. Finally, for biological application, the cytotoxicity study was performed. The probe showed low cytotoxicity and was suitable for intracellular Ag imaging. The cell imaging and in vitro photoluminescence study revealed that the probe stained the cell nucleoli and specifically bind with ribosomal RNA (rRNA) and, therefore, it can also serve as a luminescent probe for rRNA in the presence of Ag.

Ruthenium(II) Polypyridine Complex-Based Aggregation-Induced Emission Luminogen for Rapid and Selective Detection of Phosgene in Solution and in the Gas Phase

“…Over the past decade, ruthenium­(II) polypyridine complexes have become preferred as sensors and probes, as photodynamic therapeutic (PDT) agents, and for bioimaging owing to their very rich photophysical and chemical properties, including intense visible excitation and emission, a large Stokes shift, high thermal and chemical stabilities, and very low cytotoxicity. − The emission properties of ruthenium­(II) polypyridyl complexes can be readily altered by varying the structural, electronic, and coordinating sites of polypyridyl ligands. − Also, the luminescence “off–on” flexibility can be attained by the alteration of the energy gap between non-emissive 3 MC and emissive 3 MLCT states after molecular interaction with analytes. − In recent years, a sizable number of Ru­(II) complex-based sensitive and specific luminescence probes have been developed for sensing cations, anions, and biorelevant species. − However, Ru­(II) complexes for specifically detecting CWAs have rarely been reported …”

Triarylamine Rhodanine Derivatives as Red Emissive Sensor for Discriminative Detection of Ag+ and Hg2+ ions in Buffer-Free Aqueous Solutions

“…Thus, it is extremely important to detect silver ions in the aqueous media through the development of selective and sensitive methods. Efforts are being made by several research groups to develop fluorescent sensors toward silver ion detection using peptides, luminescent carbon nanomaterials, and organic and inorganic molecules and nanoparticles. − Silver detection by the chromophores is based on either the coordination with the receptors, chemical reaction, aggregation-to-deaggregation, or interaction with the nanomaterials . Another important heavy metal is mercury that is widespread in soil, air, and water because of its usage in chloralkali industries, thermal power plants, thermometers, and barometers.…”

A Novel Ruthenium(II) Polypyridyl Complex Bearing 1,8-Naphthyridine as a High Selectivity and Sensitivity Fluorescent Chemosensor for Cu2+ and Fe3+ Ions

“…Ru(II) complexes and in particular Ru(II) polypyridyl complexes have received much attention due to their potential application in the field of solar energy conversion [18,19,20,21,22], photocatalysis [23,24], water-oxidation catalyst [25,26], and luminescence sensing [27,28]. Similarly, they are applied in photodynamic therapy [29] and bio-probes [30,31,32] owing to their low cytotoxicity, redox stability, and water solubility.…”