Simultaneous Detection of Cu²⁺ and Co²⁺ by a Water‐Soluble Carboxamide‐Based Colorimetric Chemosensor

Abstract

A novel carboxamide-based colorimetric chemosensor ATA-Msal ((E)-3-((2-hydroxy-3-methoxybenzylidene)amino) thiophene-2-carboxamide) for detecting Cu 2 + and Co 2 + in aqueous solution was synthesized. Sensor ATA-Msal could probe Cu 2 + and Co 2 + by color change from colorless to pale yellow. According to results of Job plot and ESI-mass, the binding modes of ATA-Msal to Cu 2 + and Co 2 + were determined to be a 1 : 1 ratio. The detection limits (0.14 μM and 0.88 μM) of ATA-Msal for Cu 2 + and Co 2 + were much lower than WHO standard (31.5 μM for Cu 2 + ) and US Environmental Protection Agency (EPA) standard (1.70 μM for Co 2 + ). ATA-Msal can be applicable to real samples and test strips, and F À could be used to distinguish between ATA-Msal -Cu 2 + and ATA-Msal -Co 2 + . The sensing process of Cu 2 + and Co 2 + by ATA-Msal was demonstrated by UV-vis titration, ESI-mass, EPR, 1 H NMR titration, and DFT. Results and DiscussionATA-Msal was gained by the combination of 3-aminothiophene-2-carboxamide and 2-hydroxy-3-methoxybenzaldehyde with 29 % yield in ethanol (Scheme 1). It was characterized by 1 H NMR ( Figure S1), 13 C NMR ( Figure S2) and ESI-mass analysis.

A Comprehensive Review on Thiophene Based Chemosensors

“…The possible mechanism for detecting Co 3+ (oxidation of Co 2+ to Co 3+ by O 2 molecules, based on ESI mass result) and Cu 2+ could be attributed to the ICT and LMCT mechanism (Scheme 37). Furthermore, the binding modes of the sensor to Cu 2+ and Co 2+ were found to be a 1:1 binding stoichiometry [81].…”

An effective colorimetric sensor for detecting Cu2+ based on benzothiazole moiety

“…Benzothiazole groups have sometimes been employed in both chromophore and fluorophore chemosensors because of their unique spectral properties and great photostability 31,32 . Salicylaldehyde groups have often been applied as a binding site for a variety of metal ions and as a chromophore 33‐36 . Hence, we designed a sensor, 2,4‐dichloro‐6‐((E)‐(((Z)‐3‐methylbenzo[d]thiazol‐2(3H)‐ylidene)hydrazono)methyl)phenol (HMD), using a combination of benzothiazole and salicylaldehyde moieties.…”

Dual Functional Alginate‐Polyethylene Polyamine Composite Aerogel Toward Sensing and Extracting Copper Ions in Water

“…The TiO 2 −TAP combines Cu 2+ through complexing reaction with clear color change, and shows a wide detection range from 0.01 to 12.5 μM. Rha and coworkers developed a carboxamide‐based test strip for detecting Cu 2+ in aqueous solution [7] . The detection limit of this strip for Cu 2+ reaches 0.14 μM.…”