Reaction-Based Multisignal Detection of Palladium with High Sensitivity, Selectivity, and Reliability

Abstract

Due to vast application of palladium in academia and industry and its toxicity, it is critical to develop user-friendly, portable, and affordable methods for accurately detecting ultratrace Pd. In this study, a highly sensitive and selective fluorescent probe (N-butyl-4-alloxy-1,8-naphthalimide, compound 2) was synthesized, which demonstrated multiple signals [enhanced fluorescence (FL), ratiometric FL, and colorimetric responses] upon interaction with palladium. The compound 2 was designed by incorporating a naphthalimidebased fluorescent dye as the fluorophore and an allyl ether group as a responsive unit. Utilizing a Pd 0 -triggered cleavage reaction by a deallylation reaction through the Tsuji−Trost reaction, compound 2 exhibited rapid response, wide linearity, exceptional sensitivity with a limit of detection as low as 2.2 pM, and high selectivity toward palladium species. In addition, as a ratiometric and enhanced FL response, the probe could be developed as a portable sensor via naked eye visualization for semiquantitative and selective detection of palladium. Integrating with an easily available smartphone (with a camera and a color-analysis app), potential in situ quantitative detection was achieved at a low cost. The probe shows multiple signals for palladium detection and potential as a portable sensor, and this work provides valuable insights into developing sensors with good sensitivity, selectivity, improved reliability, and portability for detection of palladium and other analytes of interest.