Lower rim isoxazole-calix[4]arene derivatives as fluorescence sensors for copper(II) ions

Maher, Niall J., Diao, Haowen, O'Sullivan, Justine, Fadda, Elisa, Heaney, Frances and McGinley, John (2015) Lower rim isoxazole-calix[4]arene derivatives as fluorescence sensors for copper(II) ions. Tetrahedron, 71 (49), 9223-9233. (doi:10.1016/j.tet.2015.10.045).

Abstract

Chemosensors designed around a calix[4]arene scaffold, possessing distal isoxazole nuclei as potential recognition sites in conjugation with fluorogenic reporting moieties, have been synthesised and their molecular structures determined by single crystal X-ray analysis. PIC (pyrene-isoxazole-calix[4]arene) and AIC (anthracene-isoxazole-calix[4]arene) are found to be selective and sensitive for the recognition of copper(II) ions over a range of divalent metal ions in a spectrofluorometric study in acetonitrile. Following exposure to copper(II) ions the fluorescence emission intensity of the host was dramatically quenched, in contrast there were no significant shifts to the UV-vis spectra. ¹H NMR spectroscopic studies could not provide unambiguous evidence for the mode of ion recognition. Hybrid Density Functional Theory (DFT) calculations for the PIC-copper(II) complex suggests that the metal ion adopts tetrahedral geometry in an acetonitrile solution, while a distorted square pyramidal coordination is also possible in the absence of solvent molecules. Both of these binding conformations cause the disruption of the pyrene-pyrene stacking, consistent with the observed fluorescence quenching.

This record has no associated files available for download.

Contributors

Author: Elisa Fadda

Download statistics