Pyrenylthioureayl Alanine as a Switch‐On Fluorescent Sensor for Hg(II) Ions

Abstract

Fluorescence sensing of heavy metal ion such as mercury is highly important because of its adverse effects on biological systems and on environment. Toward this end, we report herein a new and novel pyrenylthioureayl alanine amino acid (1, PyTU Ala) as an efficient switch-on fluorescent sensor for sensing of Hg 2 + ion in semi-aqueous solvent system (7:3 H 2 O: ACN). The probe also shows binding interaction with Cu 2 + ion with an enhancement of emission. In both the cases 1:2 metalligand binding stoichiometry is evident from Job's plot analyses. The detection limit is found to be 93 nM with a very high association (10 10 M À 1 ) constant for Hg 2 + ion. The UV-visible absorption, IR-spectroscopic study, NMR titration, and a theoretical calculation supported the probe's binding to Hg 2 + ion through the coordination with two sulphur atoms of two iminothioureayl moieties of two pyrenylthioureayl alanines.Research in the field of fluorescence sensing of heavy metal as well as transition metal ions is rapidly increasing because of their adverse effects on biological systems and on environment. [1] Among the various heavy metal ion-based pollutants, the mercury ion (Hg 2 + ) is in the frontline to adversely impact the environment and human health. [2] On the other hand, the transition metal ion copper (Cu 2 + ) is important for some physiological processes. [3a-b] However, an excess amount of Cu 2 + is highly toxic to organisms. [3c-d] Therefore design of fluorescent chemosensors for both Hg 2 + and Cu 2 + is highly important for the protection of environment as well as biological systems. A tremendous numbers of literatures exist which report the design of various types of chemosensors for the detection of either Cu 2 + or Hg 2 + ion. [4] As for an example, Goswami and coworkers have designed a novel, highly selective, ratiometric and colorimetric "off-on" type fluorescence sensor for Cu 2 + ion based on 1,8-diaminonaphthalene core. The complexation via pyrrolidinium nitrogens results in a large red shifted ICT emission which is the working principle of the probe. [4c] Based on the similar concept they have also introduced another novel and selective fluorescence sensor for Cu 2 + wherein the coordinating atoms are N and O. [4d] Many other efforts have been put forth in recent times to design the fluorescence sensors specific for the sensing of both Hg 2 + and Cu 2 + ions. [5] Few reports of chemosensors also exist which rely on the change in both color and fluorescence. [6] However, many of them suffer from shortcomings such as fluorescence quenching by paramagnetic Cu 2 + and Hg 2 + ions mostly due to electron transfer mechanism [7a-b] and spin-orbit coupling [7c] respectively. Moreover, many organic chemosensors for Hg 2 + suffer from shortcomings such as-poor water solublity, adverse surrounding effects, interference by other metal ions and low detection limit. [8] Therefore, the development of fluorescent switch-on chemosensors for the detection of Cu 2 + and/or Hg 2 + is highly desirable.A fruitf...

Highly Selective and Sensitive Sulfonylhydrazone Type Fluorescent Probe for Rapid Detection of Mercury(II) and Its Application in Logic Gate and Adsorption

“…Compared with traditional mercury ion detection methods, as a highly selective and sensitive mercury ion detection method, fluorescence analysis is widely used in life sciences, environmental sciences and other fields, and is an important development direction in the field of mercury ion detection research. [33][34][35][36][37][38][39] Therefore, the design and synthesis of a new type of mercury ion probe with good selectivity and high sensitivity has always been a research hotspot. The triphenylamine unit has a unique propeller structure, excellent electron donating ability and easy-to-modify molecular structure, so it can be used as a luminescent group for small molecule fluorescent probes.…”

“…It limits its application in mercury detection. Compared with traditional mercury ion detection methods, as a highly selective and sensitive mercury ion detection method, fluorescence analysis is widely used in life sciences, environmental sciences and other fields, and is an important development direction in the field of mercury ion detection research [33–39] …”

A Lysosome-Targetable Fluorescence Sensor for Ultrasensitive Detection of Hg2+in Living Cells and Real Samples

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