Highly Sensitive and Selective Fluorescent Probes for Cu(II) Detection Based on Calix[4]arene-Oxacyclophane Architectures.
Molecules
; 25(10)2020 May 25.
Article
in En
| MEDLINE
| ID: mdl-32466180
ABSTRACT
A new topological design of fluorescent probes for sensing copper ion is disclosed. The calix[4]arene-oxacyclophane (Calix-OCP) receptor, either wired-in-series in arylene-alt-ethynylene conjugated polymers or standing alone as a sole molecular probe, display a remarkable affinity and selectivity for Cu(II). The unique recognition properties of Calix-OCP system toward copper cation stem from its pre-organised cyclic array of O-ligands at the calixarene narrow rim, which is kept in a conformational rigid arrangement by a tethered oxacyclophane sub-unit. The magnitude of the binding constants (Ka = 5.30 - 8.52 × 104 M-1) and the free energy changes for the inclusion complexation (-ΔG = 27.0 - 28.1 kJmol-1), retrieved from fluorimetric titration experiments, revealed a high sensitivity of Calix-OCP architectures for Cu(II) species. Formation of supramolecular inclusion complexes was evidenced from UV-Vis spectroscopy. The new Calix-OCP-conjugated polymers (polymers 4 and 5), synthesized in good yields by Sonogashira-Hagihara methodologies, exhibit high fluorescence quantum yields (ΦF = 0.59 - 0.65). Density functional theory (DFT) calculations were used to support the experimental findings. The fluorescence on-off behaviour of the sensing systems is tentatively explained by a photoinduced electron transfer mechanism.
Key words
Full text:
1
Database:
MEDLINE
Main subject:
Phenols
/
Piperidines
/
Copper
/
Calixarenes
/
Ethers, Cyclic
/
Receptors, Artificial
Type of study:
Diagnostic_studies
Language:
En
Year:
2020
Type:
Article