A bis-propargyl-appended rhodamine B-based receptor BPRB has been synthesised that exhibits pronounced fluorescence enhancement in the presence of Pd2+ ions. The addition of Pd2+ enhanced the fluorescence intensity of BPRB by 113-fold (Φf = 0.37) and BPRB was found to exhibit high selectivity towards Pd2+ compared to a range of other metal ions. The enhancement of fluorescence was triggered by spirolactam ring opening followed by depropargylation of BPRB in the presence of Pd2+, as evidenced by FTIR and NMR analyses. BPRB was able to detect Pd0 without the addition of a reducing agent, and the emission intensity of BPRB–Pd0 was almost identical to that of BPRB–Pd2+; however, a rapid fluorescence response was observed in the presence of PPh3. To explore the efficiency of the rhodamine unit, a bispropargyl derivative of cyclohexane (BPCH) was synthesised and the fluorescence response towards Pd2+ was examined and compared with BPRB, revealing that the rhodamine unit enhanced the fluorescence intensity by 500-fold. The fluorescence images of BPRB and BPRB–Pd2+ samples indicate that BPRB could be useful for imaging Pd2+ in living cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.