Development of Fluorescent Chemosensors for Calcium and Lead Detection

Gomes, Liliana J.; Outis, Mani; Gomes, Clara S. B.; Tomé, Augusto C.; Moro, Artur J.

http://hdl.handle.net/10362/163698

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In the present work, several coumarin-3-carboxamides with different azacrown ether moieties were designed and tested as potential luminescent sensors for metal ions. The derivative containing a 1-aza-15-crown-5 as a metal chelating group was found to yield the strongest response for Ca2+ and Pb2+, exhibiting an eight- and nine-fold emission increase, respectively, while other cations induced no changes in the optical properties of the chemosensor molecule. Job’s plots revealed a 1:1 binding stoichiometry, with association constants of 4.8 × 104 and 8.7 × 104 M–1, and limits of detection of 1.21 and 8.04 µM, for Ca2+ and Pb2+, respectively. Computational studies suggest the existence of a PET quenching mechanism, which is inhibited after complexation with each of these two metals. Proton NMR experiments and X-ray crystallography suggest a contribution from the carbonyl groups in the coumarin-3-carboxamide fluorophore in the coordination sphere of the metal ion.

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This work was supported by the Associate Laboratory for Green Chemistry—LAQV which is financed by national funds from FCT-MCTES (UIDB/50006/2020 and UIDP/50006/2020). L. J. G. acknowledges FCT-MCTES for a doctoral grant (UI/BD/153617/2022). The NMR spectrometers are part of Rede Nacional de RMN (PTNMR), supported by FCT-MCTES (grant ROTEIRO/0031/2013—PINFRA/22161/2016) (co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC). The X-ray infrastructure was financed by FCT-MCTES through project RECI/BBB-BEP/0124/2012. Publisher Copyright: © 2024 by the authors.

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azacrowns calcium coumarin-3-carboxamides fluorescent chemosensors lead metal ion detection Analytical Chemistry Chemistry (miscellaneous) Molecular Medicine Pharmaceutical Science Drug Discovery Physical and Theoretical Chemistry Organic Chemistry