Cation-dependent spectral properties of fluorescent complexon based on 1,8-naphthalimide with PET mechanism of optical response

Abstract

Complexation of 4-amino-1,8-naphthalimide derivative containing an aza-15-crown-5 ether receptor unit in the N-aryl substituent at the imide nitrogen atom of the naphthalimide core with alkaline earth metal cations was studied using optical and NMR spectroscopy. The binding of the cations with crown ether receptors was accompanied by signifacant fluorescence enhancement of naphthalimide moiety caused by the inhibition of the photoinduced electron transfer (PET) process. An increase in the cation radii on going from Mg2+ to Ca2+ to Ba2+ leads to a decrease in the complex stability and an increase in the quantum yield of its fluorescence.