Highly Selective Fluorimetric Turn‐Off Detection of Copper(II) by Two Different Mechanisms in Calix[4]arene‐Based Chemosensors and Chemodosimeters. Issue 10 (26th September 2019)

• Record Type: Journal Article
• Authors: O'Sullivan, Justine; Colleran, John; Twamley, Brendan; Heaney, Frances
• Is Part Of: ChemPlusChem. Volume 84:Issue 10(2019)
• Page Start: 1610
• Page End: 1622
• Publication Date: 2019-09-26
• Subjects: calixarenes -- copper -- electrochemistry -- fluorescent probes -- sensors; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cplu.201900448
• Languages: English
• ISSNs: 2192-6506

Abstract

Abstract: Isoxazolo‐pyrene tethered calix[4]arenes selectively detect copper(II) ions without interference from related perchlorate ions. The fluorescence emission of the probes, synthesised by nitrile oxide alkyne cycloaddition, and characterised by spectroscopic and crystallographic data, is rapidly reduced by Cu(II) ions. Detection limits are in the micromolar or sub‐micromolar range (0.3–3.6 μM) based on a 1 : 1 sensor:analyte interaction. Voltammetric behaviour and 1 H NMR data provide new insights into the sensing mechanism which is dependent on the calixarene substitution pattern. When the calixarene lower rim is fully substituted, Cu(II) detection occurs through a traditional chelation mechanism. In contrast, for calixarenes 1, 3‐disubstituted on the lower rim, detection takes place through a chemodosimetric redox reaction. The isolation of a calix[4]diquinone from the reaction with excess Cu(ClO4 )2 provides confirmation that the sensor–analyte interaction culminates in irreversible sensor oxidation. Abstract : Cu switch off : Fluorescence emission of isoxazolo‐pyrene tethered calix[4]arene probes is selectively quenched by copper(II) ions. The sensing mechanism, traditional chelation or chemodosimetric redox activity, is shown by voltammetric and 1 H NMR data to be dependent on the lower‐rim substitution pattern. Isolation of a calix[4]diquinone from reaction with excess Cu(ClO4 )2 confirms the sensor−analyte interaction.