Series of Fluorescent Dyes Derived from Triphenylamine Structure for Cu²⁺ and In-Cell Carbon Monoxide Sensing: Synthesis and Performance

In this paper, triphenylamine served as the structural core and was bonded to aromatic groups having various substituents [-OH, -OMe, or -N(Et)₂] by a =N-N= chain and then connected with aromatic groups having various substituents [-OH, -OMe, or -N(Et)₂]. The geometric and electronic properties of these probes were examined. It was found that the presence of electron donors enhanced the selectivity and emission quantum yield (QY). When exposed to Cu²⁺, the fluorescence intensity decreased. The optimal probe (T₅) showed a significant decrease in emission QY from 17.1 to 0.5% and recovered to 16.8% after exposure to CO for 342 s. The sensing mechanism was revealed to be static quenching, forming a nonfluorescent adduct between probe and Cu²⁺. After reacting with CO, Cu²⁺ was reduced to Cu⁺, and the probe emission was recovered. The bioimaging performance of the optimal probe was assessed as well.