Synthesis and cation‐sensitive fluorescence of polyelectrolytes bearing crown ether side groups

Abstract

AbstractPolyelectrolytes bearing crowned acetophenone moieties were prepared by radical copolymerization of 4′‐acryloylbenzo‐18‐crown‐6System. name of benzo‐18‐crown‐6: 1,2‐benzo‐1,4,7,10,13,16‐hexaoxa‐2‐octadecene. and methacrylic acid or lithium 2‐acrylamido‐2‐methyl‐1‐propanesulfonate. On excitation with 330 nm light the polymers showed fluorescence at 410 nm in a mixed solvent of methanol and water (1:9 v/v) at 30°C. When cations were added, the fluorescence intensity of the polymers decreased in the orders Li+ > Na+ > Cs+ > Rb+ > K + for alkali metal cations, Ca2+ > Sr2+ > Ba2+ for alkaline earth metal cations and C2H5NH2 > CH3(CH2)3NH2 > C6H5CH2NH2 for alkylamine hydrochlorides used. The concentration effect for cations in the neighborhood of the polymer‐bound crown ether groups by electrostatic and/or hydrophobic binding induced significant complex formation between cations and crown ethers in aqueous solutions, resulting in a decrease of the fluorescence intensity.