Complexation behaviors of polyether-type fluorescent reagents having anthracene units at their terminals

A new fluorescent reagent, N,N'-(4,7,10-trioxatridecane-1, 13-diyl)bis(anthracene-9-carbonamide) (5), and its analogues(1-4 and 6), which have two anthracene moieties at both terminals of linear polyethers, were synthesized. Their complexation behavior with alkaline earth cations was investigated by fluorescence spectrometry, fluorescence life- time, and ¹H NMR spectrometry. When metal ions were added to these reagent solutions, fluorescence spectral changes were observed. In particular, 5 showed a drastic change in the fluorescence spectra accompanied by metal ion binding. The fluorescence spectra of 5 completely changed from that of monomer to excimer emission. All reagents formed a 1 : 1 complex with alkaline earth cations. The ¹H NMR spectra of 5 with alkaline earth cations suggested the stacking of two anthracene moieties with each other. However, the interactions between two anthracenes were weak on the ground state for the other compounds (1 - 4 and 6).