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Highly Sensitive and Selective Fluorescent Probes for Cu(II) Detection Based on Calix[4]arene-Oxacyclophane
Alexandra I Costa1,2, Patrícia D Barata1,2, Carina B Fialho1
1Departamento de Engenharia Química, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, R. Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal.
Molecules (Basel, Switzerland)
|May 30, 2020
Summary
A novel fluorescent probe using calixarene-oxacyclophane (Calix-OCP) demonstrates high sensitivity and selectivity for detecting copper ions (Cu(II)). This design offers a promising tool for sensitive copper ion detection in various applications.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Analytical Chemistry
Background:
- Copper ions (Cu(II)) are crucial in biological systems but toxic at high concentrations.
- Developing selective and sensitive fluorescent probes for Cu(II) detection is essential for environmental and biological monitoring.
- Existing methods for Cu(II) detection often lack selectivity or sensitivity.
Purpose of the Study:
- To design and synthesize a novel fluorescent probe based on calixarene-oxacyclophane (Calix-OCP) for selective copper ion sensing.
- To investigate the binding affinity, selectivity, and sensing mechanism of the Calix-OCP system towards Cu(II).
- To evaluate the performance of Calix-OCP as a standalone probe and when integrated into conjugated polymers.
Main Methods:
- Synthesis of calixarene-oxacyclophane (Calix-OCP) receptor and Calix-OCP-conjugated polymers.
- Fluorimetric titration experiments to determine binding constants and free energy changes.
- UV-Vis spectroscopy to confirm supramolecular complex formation.
- Density Functional Theory (DFT) calculations to support experimental findings.
Main Results:
- Calix-OCP exhibits remarkable affinity (Ka = 5.30 - 8.52 × 10^4 M^-1) and selectivity for Cu(II).
- The pre-organized structure of Calix-OCP ensures conformational rigidity for effective copper ion recognition.
- Calix-OCP-conjugated polymers show high fluorescence quantum yields (ΦF = 0.59 - 0.65) and a fluorescence "on-off" sensing behavior.
- Photoinduced electron transfer (PET) mechanism is proposed to explain the fluorescence quenching.
Conclusions:
- The developed Calix-OCP based fluorescent probes demonstrate high sensitivity and selectivity for Cu(II) detection.
- The unique topological design of Calix-OCP provides a robust platform for developing advanced chemical sensors.
- This work offers a new avenue for designing efficient fluorescent probes for metal ion sensing applications.
