Colorimetric and fluorescent probes for real-time naked eye sensing of copper ion in solution and on paper substrate

Abstract

In this paper, BT ((E)-2-(4-(4-(bis(pyridin-2-ylmethyl)amino)styryl)-3-cyano-5,5-dimethylfuran-2(5H)-ylidene)malononitrile) with strong donor–π-acceptor structure was synthesized, which showed both colorimetric and fluorescent sensing ability toward Cu2+ with high selectivity and sensitivity. Job plot and mass spectra measurement revealed a 1 : 1 coordination mode between Cu2+ and probe BT in ethanol/HEPES (1 : 4 v/v) buffer (pH 7.2) solution, and the binding constant was calculated to be 3.6 × 104 M–1. The colour of BT solution (10 µM) immediately turned from purple red to yellow and the red fluorescence was quenched obviously when a certain amount of Cu2+ was added, which enabled a dual-channel detection of Cu2+. A paper strip pre-stained with BT solution was further fabricated and it also showed excellent sensing ability toward Cu2+ with a detection limit as low as 10−6 M with the naked eye, which represents better portability and operation simplicity that is favourable for on-site analysis of Cu2+ in water.

Ruthenium(II)‐Polypyridyl‐Based Sensor Bearing a DPA Unit for Selective Detection of Cu(II) Ion in Aqueous Medium

“…− However, Ru‐L in presence of Cu 2+ ion was substantially sensitive to both acidic as well as basic pH. The emission intensity of Ru‐L–Cu increased obviously at low pH (5.0‐3.0), due to the competition between the H + and Cu 2+ ions . On further increase of the pH, the emission intensity almost remained constant up to pH 9.0.…”

“…A di‐(2‐picolyl)amine (DPA) moiety was tethered to the phenanthro‐imidazole unit via a phenyl‐CH 2 linker. DPA moiety linked with a fluorophore has already been reported as a promising binding site to Cu(II) with good selectivity However, in most of the cases, the detection was performed either in neat organic or organic‐water solvent systems and rarely reported in fully aqueous medium.…”

Exploring Colorimetric Real-Time Sensing Behavior of a Newly Designed CT Complex toward Nitrobenzene and Co2+: Spectrophotometric, DFT/TD-DFT, and Mechanistic Insights

“…Too acidic environment may protonate the pyrrole moiety, which reduces the coordination ability, and too basic environment may reduce the free Co 2+ ions in solution and influence the sensitivity. 59…”

A Simple Naphthamido‐based Fluorescent Chemoprobe for the Detection of Uranyl Ions

“…These results demonstrated that the fluorescence intensity of probe 1 was effectively enhanced by UO 2 2+ with such a metal ion as the background. Thus, probe 1 exhibits excellent selectivity for UO 2 2+ except for Ca 2+ and Rb + …”