Rapid Communication: Synthesis and Electrochemical Studies on a Crown Ether Bearing a Naphthoquinone Acceptor

Abstract

The bichromophoric crown ether N18C6NQ (1) has been synthesized in three steps from readily available starting materials. The main theme of the synthetic strategy involves the conjugate addition of an alcohol to 2,3-dichloronaphthoquinone in the presence of a base. Preliminary electrochemical and photophysical studies on (1) have been undertaken. The addition of alkali metal cations to the crown ether (1) causes significant changes in the first and second reduction potentials of the naphthoquinone (NQ) chromophore. In the case of the first process, a correlation between the reversible potential and cation ‘fit’ exists. The steady-state fluorescence spectra of (1) are quenched substantially (> 90%) as compared with the model (2) in both CH₂Cl₂ and dimethylformamide solution. These systems are of interest in the development of a new family of crown ether based photosynthetic mimics and ion-selective sensors.