Coumarin Based Highly Selective “off-on-off” Type Novel Fluorescent Sensor for Cu2+ and S2− in Aqueous Solution

Abstract

Solvent free synthesis of 6,7-dihydroxy-3-(3-chlorophenyl) coumarin (CFHC) was designed and obtained by the interaction of 2-(2,4,5-trimethoxyphenyl)-1-(3-chlorophenyl)acrylonitrile with pyridinium hydrochloride in the presence of silica gel by using microwave irradiation. The characterization of CFHC was confirmed by FT-IR, H,C, C-APT and 2D HETCOR spectroscopy methods. The optical behavior of CFHC towards metal ions was investigated by UV-visible and fluorescence spectroscopy. CFHC showed "on-off" type fluorescence response towards Cu with high selectivity in aqueous solution (CHCN/HO, 9/1, v/v). Once binding with Cu, CFHC-Cu complex also displayed high selectivity for sulfide, resulting in "off-on" type sensing of sulfide anion. Graphical abstract Visual fluorescence changes upon addition of various metal ions (5.0 eq.) to CFHC in CHCN/HO (90:10, v/v) under UV excitation (365 nm).

Coumarin-Based Small-Molecule Fluorescent Chemosensors

“…Finally, Nihan Karuk Elmas et al. described a cathecol type coumarin 282 (Figure ), exhibiting a dramatic reduction in fluorescence in the presence of Cu 2+ . Similarly to the examples above, the addition of Na 2 S restored the fluorescence.…”

“…A selective visual fluorescence change upon addition of Cu 2+ ion to 282 solution over other various metal ions (5.0 equiv). Reproduced with permission from ref . Copyright 2017 Springer Nature.…”

Pyridinyl Conjugate of UiO-66-NH2 as Chemosensor for the Sequential Detection of Iron and Pyrophosphate Ion in Aqueous Media

“…Beyond this range, the fluorescence emission properties were lost, which was probably due to breaking the imine linkage or destruction of the UiO-66-N-Py framework. The fluorescent enhancement mechanism was due to the release of Fe 3+ from the UiO-66-N-Py + Fe 3+ complex by the metal-MOF displacement method by PPi (Scheme 2) [31][32][33]. This was confirmed by the restoration of the emission peak of the pristine UiO-66-N-Py at 485 nm after interaction with PPi.…”

“…The material obtained after the first experiment was washed with water and methanol and then dried at 110 • C for 5 h. The recovered UiO-66-N-Py showed an identical change in the emission intensities and sensitivities toward the detection of analytes for six consecutive cycles ( Figure 10). The fluorescent enhancement mechanism was due to the release of Fe 3+ from the UiO-66-N-Py + Fe 3+ complex by the metal-MOF displacement method by PPi (Scheme 2) [31][32][33]. This was confirmed by the restoration of the emission peak of the pristine UiO-66-N-Py at 485 nm after interaction with PPi.…”

Small Molecule Optical Probes for Detection of H2S in Water Samples: A Review

“…Nitrogen and sulfur can serve as suitable metal ion binding sites to facilitate colorimetric sensing of H 2 S based on a metal displacement approach. , The strong affinity of S 2– for transition metal ions including Cu 2+ ( K sp for CuS = 6310–36) and Hg 2+ ( K sp for HgS = 2310–53) is advantageous to develop probes with a fast response time and reversibility. − Choe and Kim constructed a colorimetric H 2 S complex probe 35 based on benzothiadiazole as the A group and julolidine as the D unit . The violet colored 35 -Cu 2+ chromogenic chemosensor and coated test strips could detect H 2 S in real water samples via a cation displacement process.…”