A depropargylation-triggered fluorescence “turn-on” probe for the detection of Pd2+ based on a bispropargylamine–rhodamine conjugate

Abstract

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.

Revisit of a dipropargyl rhodamine probe reveals its alternative ion sensitivity in both a solution and live cells

“…The structure of the compound was characterized by NMR and MS. With the propargyl RB in hand, we measured its ion sensitivity with a range of metal cations in a solvent system (MeCN/H 2 O [1 : 1, V/V]) identical to that used in ref. 18. As shown in Fig.…”

“…1a, inset), has been identied as a Pd 2+ probe. 18 The authors proposed that the probe undergoes a palladium-catalyzed depropargylation which then induces ring-opening of the spirolactam of RB leading to FL enhancement. Among a variety of metal cations, the probe was shown to be specic for Pd 2+ .…”

“…This agrees with that reported in ref. 18. Nevertheless, the FL of the probe also enhanced tangibly in the presence of Hg 2+ that had not been chosen as a competing ion in the reference.…”

Fluorescent carbon nanoparticles for sensitive and selective detection of palladium (Pd2+)

“…The residual palladium can then be accumulated in food chain and bind with the biothiols, DNA, proteins and Vitamin B, which could impose significant risk on human health. 37 For example, the U.S. federal agency restricts the threshold limit of final concentration of the palladium in drug chemicals in the range of 47.0 to 94.0 µM. 38 Consequently, there exists an urgent need to develop a novel, sensitive and selective probe for palladium sensing.…”

Sequential Detection of Palladium and Chromium Oxyanion by a Fluorescein Based Chemosensor in Mixed Aqueous Media

“…Recently, optical (colorimetric and fluorescent) chemosensors or probes have attracted more and more importance for sensing and monitoring of heavy and transitional metal ions (HTM) due to its high selectivity, sensitivity, operational simplicity, rapidity, and nondestructive nature [11][12][13][14][15]. One of the common ways to synthesize a palladium sensor is to use palladium catalyzed reactions such as Pd-catalyzed cyclization for the formation of pyrone, pyrrole, and oxazole [16,17], Pd-catalyzed depropargylation reactions [18] and deallylation reactions [19], the Pd-catalyzed Heck [20], and the Suzuki-Miyaura coupling reactions [21]. However, many of them still have impediments such as interference from other metal ions, insolubility in water, requirement for additional reagents for analysis, and laborious synthesis procedures with expensive chemicals.…”