What question did this study set out to answer?

The research aims to explore coumarin-3-carboxamide derivatives as chemosensors for detecting specific metal ions.

February 24, 2026ChemistryEurope0 citationsOpen Access

Coumarin‐3‐Carboxamide Derivatives as Colorimetric/Fluorescent Chemosensors for the Detection of Ca 2+ , Mg 2+ , Pb 2+ , and Selective Recognition of Cu 2+

LGLiliana J. GomesUniversidade Nova de Lisboa LMLuísa B. MaiaUniversidade Nova de Lisboa MOMani OutisUniversity of Lisbon

Key Points

The research aims to explore coumarin-3-carboxamide derivatives as chemosensors for detecting specific metal ions.
Synthesis of 7‐(diethylamino)coumarin‐3‐carboxamides with different aza‐crown moieties.
Conducting optical spectroscopy, X‐ray crystallography, and EPR experiments.
Evaluation of colorimetric and fluorescence responses to various metal ions (Ca2+, Mg2+, Pb2+, Cu2+).
The chemosensors demonstrated strong colorimetric and fluorescent ON–OFF behavior in response to the presence of metal ions.
Higher affinity was observed for Cu2+, even amidst other cations in solution.
An irreversible oxidation reaction occurs in the presence of Cu(II), leading to the formation of Cu(I) and a radical species, resulting in a visible color change.

Abstract

Herein, we present a family of 7‐(diethylamino)coumarin‐3‐carboxamides, bearing three different aza‐crown moieties (chelating unit). All synthesized compounds have shown a colorimetric response and fluorescence ON–OFF behavior to the presence of lead, calcium, magnesium, and copper, with higher affinity toward the latter, even in the presence of other cations in solution. Optical spectroscopies, X‐ray crystallography, and EPR experiments show that Cu(II) induces an irreversible oxidation on the coumarin core, with the concomitant formation of Cu(I) and an organic radical species. The emergence of an absorption band in the visible region upon radical formation results in the appearance of blue color, which fades over time, highlighting the potential of these sensors for rapid detection of copper(II) ion under the naked eye.

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