Fluorescence response of structurally simple fluorophore - spacer - receptor systems towards transition metal ions and protons

Abstract

Two new multicomponent systems with fluorophore-spacer-receptor architecture employing 4-aminophthalimide and 4-amino-1,8-naphthalimide fluorophores and aniline receptor have been developed and their fluorescence response towards quenching transition metal ions and protons has been investigated. The low fluorescence quantum yields of the supramolecular systems compared with those of the free fluorophores have been interpreted in terms of photoinduced intramolecular electron transfer (PET) in the systems. In the presence of the d-block metal ions, known for their quenching abilities, the supramolecular systems exhibit fluorescence enhancement rather than quenching. This observation has been interpreted taking into consideration of PET-quenched short fluorescence lifetime of the fluorophores. The systems reported here can be considered as potential candidates as fluorosensors for the transition metal ions and protons.