A pyrene-linked thiourea as a chemosensor for cations and simple fluorescent sensor for picric acid

Abstract

5Pyrene linked simple thiourea has been synthesized and receptor 1 acts as fluorescence and visual sensor for the detection of Cu 2+ and Hg 2+ ions. The sensor showed effective detection of Cu 2+ and Hg 2+ at a low detection limit. Receptor 1 has been successfully applied to fluorescence imaging of Cu 2+ and Hg 2+ ions in living cells. Also receptor 1 selectively detects picric acid via color change and fluorescence change.

π-Electron rich small molecule sensors for the recognition of nitroaromatics

“…Unlike 28, molecular structure analysis of 29 revealed that it does not form such supramolecular polymeric structure due to the lack of required H-bonding interactions. Compounds 28─30 exhibited strong emission in solution with estimated quantum yields of Φ = 0.21 (28); 0.23 (29) and 0.47 (30). The fluorescence quenching titration study of 28─30 with picric acid 5 demonstrated that, as expected, the quenching efficiency followed the order 28>29>30.…”

“…A 130 chemosensor 9 based on pyrene-linked with thiourea was synthesized and used as selective probe for PA over other NACs in solution. 30 Sensor 9 was synthesized by simple condensation reaction between N-phenylthiosemicarbazide and pyrene-1carboxaldehyde in ethanol. The strong fluorescence emission of 9 (Φ = 0.045) was quenched (Φ = 0.015) completely including a sharp visual color change from pale yellow to green in presence 5 of up to 2 equiv.…”

“…The addition of other NACs such as 4-nitroaniline (4-NA), 2-nitrophenol (2-NP), NB, 2-nitrobenzaldehyde (2-10 NBAl), 1-bromo-2-nitrobenzene (Br-2NB), 4nitrobenzoylchloride (4-NBOCl) elicited no fluorescence quenching. 30 Chart 3: Pyrene functionalized tetracarboxylic acids and their esters 15 analogous. 20 25 30 In 2013, Fang et al synthesized a novel terthiophene-pyrene conjugate (10) employing Grignard reaction and screened as selective probe for NACs.…”

“…Recently, Mukherjee and co-workers designed π-electron-rich anthracene based fluorophore 26 bearing trimethylsilylethynyl (TMS) groups. 26 The attachment of bulky- 30 TMS groups on the peripheral of anthracene-core further increase the conjugation through interaction between C─Si σ bonds and C≡C π bonds and also prevents the self-quenching of the fluorophore. The intense emission of 26 in CHCl 3 solution quenched efficiently upon addition of nitroaromatics such as TNT 35 and PA as low as ppb concentration; whereas, the addition of electron-deficient non-nitroaromatics such as BQ, BA etc.…”

“…Excess inhalation of TNT may cause abnormal liver function and also may lead to severe neurological damages. 4 According to US Environmental Protection Agency (EPA), the permissible level of TNT in drinking water is ~2 ppb and above that level it is 30 considered as toxic. 5 Therefore, suitable sensors with high sensitivity and discriminating ability for the trace identification of NACs in soil, groundwater land mines area have high demand.…”