W.Q. Li

A highly selective colorimetric chemosensor for detection of iodide ions in aqueous solution

We synthesized a new iodide ion (I−) chemosensor (CS) based on a hydrazone derivative obtained from the condensation of 2-hydroxy-1-naphthaldehyde and 2,4-dinitrophenylhydrazine. The CS showed selective colorimetric recognition of I−, the miscellaneous competitive anions (F−, Cl−, Br−, HSO4−, CH3COO−, H2PO4−, SCN−, CN−, ClO4− and S−) did not lead to any significant interference. The detection limits of the CS for I− is 1.1 × 10−6 M. The sensor has been successfully applied to estimate the content of iodide ions in urine. Moreover, ion test strips based on CS were fabricated, which could act as a convenient and efficient I− test kit for “in-the-field” measurement of iodide ions.

A highly selective fluorescent chemosensor for successive detection of Fe3+ and CN- in pure water

Abstract A water-soluble fluorescent chemosensor (D) based on 1, 8-naphthalimide derivative has been designed and synthesised as a new fluorescent sensor for successive detection of Fe3+ and CN−. Fluorescence measurements show that chemosensor D has excellent fluorescent-specific selectivity and high sensitivity for Fe3+ over many other metal ions in pure water. Moreover, the complex of D and Fe3+ (D–Fe3+) displayed high sensitivity for CN− over many other anions in the same medium. Even more important, the recognition of the sensor D for Fe3+ and D–Fe3+ complex for CN- could be used successfully in pure water. The test strips based on D and D–Fe3+ exhibited good selectivity to Fe3+ and CN,- respectively, we believe the test strips could serve as convenient and efficient Fe3+ and CN− test kits.

A highly selective colorimetric and “Off-On” fluorescence sensor for CN − based on Zn(salphenazine) complex

The development of sensors for selective detection of cyanide ion (CN−) is an important mission to accomplish because of the versatility and toxicity of CN−. In the present work, an “ensemble”-based colorimetric and fluorescent sensor (L2-Zn2+) for CN− ion has been developed. The addition of cyanide ions removed Zn2+ from the ensemble (L2-Zn2+) in aqueous medium, resulting in a color change of the solution from red to buff and a “turn-on” fluorescent response. Also, the sensitivity of both the fluorescence- and colorimetric-based assay is below the maximum allowable level of cyanide ions in drinking water set by the World Health Organization. In addition, test strips, which served as convenient and efficient CN− test kits, were fabricated based on the sensor. Notably, the selective detection of cyanide with L2-Zn2+ for practical application was also performed in sprouting potatoes.

Mercaptooxazole–phenazine based blue fluorescent sensor for the ultra-sensitive detection of mercury(II) ions in aqueous solution

Herein, a mercury(II) ion fluorescent sensor (Z-3) with high sensitivity and immediate response is designed and synthesized. The sensor uses the phenazine group as a luminophore and sulfhydryl as a recognition moiety. The sensor is easily synthesized and it exhibits a remarkable blue shift with Hg2+. Correspondingly, its fluorescence color changes from yellow to blue. In addition, the low naked eye detection limit (10−5) of the sensor allows the identification of concentration limits. Moreover, the sensor could detect mercury(II) ions over a wide pH range (from 2 to 8), which indicates that the detection can be carried out in aqueous systems. In addition, test strips are fabricated, which could act as a convenient pathway for the recognition of Hg2+.

A Water Soluble Naphthalimide-Based Chemosensor for Fluorescent Detection CN− in Pure Water and Its Application in Practical Samples

By rationally introducing aromatic carboxyl functionalized 1,8-naphthalimide, a water soluble fluorescent chemosensor (DA) was successfully synthesized. It could selectively and sensitively detect CN− in pure water via an intramolecular charge transfer to twisted intramolecular charge transfer (ICT-TICT) state change mechanism. The detection limit of the chemosensor DA to CN− was 1.38 × 10 mol L which was lower than 1.9 μmol L (set by the World Health Organization (WHO)). Notably, DA displayed rapid response (about 1 s) for recognizing CN− in pure water. Furthermore, DA could be applied to monitoring CN− in tap water. Meanwhile, we prepared the test strips based on DA, which could rapidly and efficiently detect CN− in water.

A novel self-assembled supramolecular sensor based on thiophene-functionalized imidazophenazine for dual-channel detection of Ag+ in an aqueous solution

Herein, a novel self-assembled supramolecular sensor (S1) based on thiophene-functionalized imidazophenazine for Ag+ was designed and synthesized. It showed dual-channel detection properties for Ag+ based on the competitive mechanism of supramolecular self-assembly with high sensitivity and selectivity even in the presence of other metal ions. Its detection limit for Ag+ is 8.18 × 10−9 M. Upon the addition of Ag+, the solution changes from yellow to light purple and the fluorescence is quenched. Furthermore, the sensing mechanism between Ag+ and S1 is investigated via IR and 1H NMR spectroscopy, mass spectrometry, and density functional theory calculations.