Ferrocenyl derivative of 1,8-naphthalimide as a new turn-on fluorescent sensor for Au(III) ion

Two new compounds containing a ferrocene unit and a strongly fluorescent naphthalimide moiety were designed and successfully synthesized. The incorporation of a hydrophilic triethylene glycol unit can enhance the water-solubility and facilitate the dispersion of compounds in aqueous media. The presence of the ferrocene unit in both compounds results in molecules with low quantum efficiencies due to the photo-induced electron transfer (PET) from naphthalimide to ferrocene. However, one of these compounds exhibits a selective fluorescent turn-on by the addition of Au(III) ion with low to negligible interference by 100-fold concentration of other metal ions in acetonitrile/water. Under optimum conditions, the detection limit for Au(III) ion was 95 ppb. (C) 2014 Elsevier Ltd. All rights reserved.