[SCAN] Ultrasensitive colorimetric chemosensors for copper(II) detection and quantification in environmental samples

Title: Ultrasensitive colorimetric chemosensors for copper(II) detection and quantification in environmental samples

Speaker: Luís Lima

Abstract: The design of chemosensors for metal cations with facile, selective and ultrasensitive detection ability is a continuing challenge, and copper(II) is especially relevant while being a common environmental pollutant with several adverse effects in human health.

This talk describes two novel and highly efficient colorimetric Cu2+ chemosensors, L1 [1] and L2 [2], which were synthesized and thoroughly studied in aqueous methanol media. Both sensors yield an intense visible absorption when in presence of Cu2+ in pH=7 buffered media, unlike for any other tested cation and considerably redshifted from the sensors’ own absorptions. The ratiometric response of the sensors displays remarkably low limits of detection (LoD) at 3.7 or 2.3 nM, respectively for L1 and L2. Furthermore, some impressive 1.5 or 0.5 μM LoD are possible simply by naked-eye observations, well below the 31.5 μM (2 mg/L) guidelines for drinking water established by the World Health Organization.

The sensors were characterized in their Cu2+ binding equilibrium, speciation, and structure by UV-vis spectrophotometry, while the robustness of the sensing phenomena with regard to reversibility and to competition from other cationic species was established. The application of both sensors to quantification of Cu2+ levels in tap water samples will be demonstrated, both directly and after spiking the samples with additional Cu2+.

[1] Fanna, D. J.; Lima, L. M. P.; Craze, A. R.; Trinchi, A.; Wuhrer, R.; Lindoy, L. F.; Wei, G. ; Reynolds, J. K. ; Li, F.; ACS Omega, 2018, 3, 10471–10480.

[2] Fanna, D. J.; Lima, L. M. P.; Craze, A. R.; Trinchi, A.; Wei, G.; Reynolds, J. K.; Li, F.; J. Inclusion Phenom. Macrocycl. Chem., 2019, 94, 141–154.