Fluorescenttren-based 4-amino-1,8-naphthalimide sensor for Cu(II) based on the use of the (fluorophore–spacer–receptor) photoinduced electron transfer (PET) principle

Veale, Emma B., Kitchen, Jonathan A. and Gunnlaugsson, Thorfinnur (2013) Fluorescenttren-based 4-amino-1,8-naphthalimide sensor for Cu(II) based on the use of the (fluorophore–spacer–receptor) photoinduced electron transfer (PET) principle. Supramolecular Chemistry, 25 (2), 101-108. (doi:10.1080/10610278.2012.752088).

Abstract

The design, synthesis and photophysical evaluation of a new chemosensor for copper [Cu(II)] is described based on the use of a functionalised 1,8-naphthlimide structure substituted at the 4-position with a tris(2-aminomethyl)amine-based (tren) ligand as a receptor for Cu(II). The sensor 1 functions as a classical photoinduced electron transfer sensor for protons, where the 4-amino-1,8-naphthalimide emission, occurring in the green part of the electromagnetic spectrum, is reversibly switched ‘ON–OFF’. A screen of various groups I and II as well as d-metal ions showed that only in the case of Cu(II), in buffered 100 mM NaCl solution, was the emission of 1 modulated, being quenched by ca. 80% upon addition of one equivalent of CuCl2 in buffered solution. The emission was, however, reversibly switched back ON, by the addition of either EDTA or glutathione. While only small changes occurred in the ground state, analysis of the changes in the emission spectra at various pH values showed that Cu(II) was detected through the formation of either a 2:1 or a 1:1 (ligand to metal) stoichiometry. The overall changes in the emission spectra of 1 as a function of H+ and Cu(II) can also be described as a molecular-level logic gate operation, corresponding to a two-input INHIBIT function.

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Contributors

Author: Jonathan A. Kitchen

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