Design of a novel coumarin-based multifunctional fluorescent probe for Zn2+/Cu2+/S2− in aqueous solution

Abstract

A multifunctional fluorescent chemosensor 7-(diethylamino)-coumarin-3-carbaldehyde-(2'-methylquinoline-4'-formyl) hydrazone (HL) has been designed and synthesized. The sensor shows significant fluorescence enhancement in the presence of Zn(2+), which might be mainly due to the restricted -CN isomerization process. In contrast, the fluorescence of the sensor is quenched by Cu(2+) attributed to the inherent paramagnetic species. More interestingly, the 'in situ' prepared L-Cu exhibits a selective response to S(2-) based on reversible formation-separation of complex L-Cu and CuS.

Fluorogenic Polyfunctional Coumarin-Based Chemosensors for Multianalyte Detection

“…Coumarin 20 exhibits a significant increase in fluorescence intensity at 514 nm in the presence of Zn 2+ ions, which is associated with the cessation of C=N isomerization process [48]. The detection limit reached at 5.76 × 10 −7 M. As expected, the Cu(II) cations almost completely quenched this fluorescence due to their inherent paramagnetic properties (Figure 20).…”

Characterization of a highly Al3+‐selective fluorescence probe based on naphthalimide‐Schiff base and its application to practical water samples

“…Additionally, the UV–Vis titration experiment of L was performed with Al 3+ in ethanol/Tris–HCl buffer solution (1:1, v /v, pH = 7.2) to study the mode of L with Al 3+ at room temperature . The changes in the absorption spectra of L as a function of the concentration of Al 3+ were given in Figure .…”

A Bifunctional “Off‐On” Fluorescence Probe Based on Naphthalene for the Detection of Ag+ and Al3+ and Its Application in Practical Water Samples, as a Logic gate and as Test Paper

“…After adding 1 equivalent amount Ag + , the signals of H 1 and H 8 shifted toward the low-magnetic field own to the local electron cloud density decreased, which were caused by the coordination of S atom and N atom with Ag + , the chelation of PCT and Ag + formed a stable six-membered ring structure. [1,[39][40][41] Similarly, 1 H NMR spectra of PCT and PCT-Al [42][43][44][45] The signals of H 10 split from a single peak into double peaks as a result of the imino N atom coordinated with Al 3 + , which limited the rotation of C=N and the chelation of PCT and Al 3 + forming two stable sixmembered ring structures. [46][47][48] The possible mechanism of sensing Ag + and Al 3 + is described in Scheme 1.…”