Phenazine-based fluorescence probes for simultaneous sensing of silver and iodide ions

The selective and sensitive detection of silver ions (Ag+) and iodide ions (I−) is of paramount importance in various scientific and industrial domains. In this paper, we present phenazine-based fluorescence probes, synthesized through a scalable and straightforward procedure, for the simultaneous sensing of Ag+ and I−ions in solution phase. The introduction of Ag+ led to ratiometric changes, manifesting in alterations of both solution color (from colorless to yellow) and fluorescence signal (from blue to cyan). Mechanistic investigations unveil that Ag+ coordinate with the phenazine nitrogen ends, forming self-assembled nanostructures characterized by significant charge-transfer properties. Moreover, we observed that the nature of the terminal alkyl residue played a pivotal role in governing the binding interaction with Ag+, with aliphatic residues featuring positively charged quaternary nitrogen ends exhibiting notably reduced responses. Additionally, the in-situ formed metal complex, comprising 1.Ag+, proved to be highly effective in selectively analyzing I− ions. The exceptional binding affinity of Ag+ for I− ions, marked by an exceptionally low solubility product constant, facilitated the sequestration of Ag+, ultimately leading to the formation of free probe in the reaction medium. Our research showcases the capability of phenazine-based probes in selective ion sensing applications, and their adjustable properties position them as promising options for a range of analytical and diagnostic uses.