Multifunctional dendritic molecular probe for selective detection of Cu2+ ions using potentiometric and fluorometric techniques

Abstract

We have designed and synthesized a multifunctional dendritic molecular probe that selectively detects Cu²⁺ ions via potentiometric and fluorometric techniques with low detection limits (3.5 μM in potentiometry, 15 nM in fluorometry). The selective and reversible binding of the molecule with the Cu²⁺ ion was used to make a solid-state microsensor (diameter of 25 μm) by incorporating the molecular probe into the carbon-based membrane as an ionophore for Cu(II). The Cu(II) microelectrode has a broad linear range of 10 μM to 1 mM with a near Nernstian slope of 30 mV/log [a_Cu²⁺] and detection limit of 3.5 μM. The Cu(II) microsensor has a fast response time (1.5 s), and it has a broad working pH range from 3.5 to 6.0. The incorporation of the hydrophobic dendritic moiety makes the ionophore less prone to leaching in an aqueous matrix for potentiometric measurement. The cinnamaldehyde component of the molecule helps detection of Cu²⁺ ions fluorometrically, as indicated by a change in fluorescence upon selective and reversible binding of the molecular probe to the Cu²⁺ ions. The strategic design of the molecular probe allows us to detect Cu²⁺ ions in drinking water by using this novel dendritic fluoroionophore and solid-state Cu²⁺ – ion-selective microelectrode.