Towards the development of Eu(III) luminescent switching/sensing in water-permeable hydrogels

The synthesis of the Eu(III) complex 1.Eu and photophysical studies of this complex in solution are described. In water, the Eu(III) luminescence was ‘switched on’ in the presence of H+, with large enhancements in the Eu(III) luminescence. The complex was then incorporated into poly[methylmethacrylate-co-2-(hydroxyethylmethacrylate)]-based hydrogels and the luminescent properties of the resulting polymeric films were investigated using confocal laser-scanning microscopy as well as using steady-state luminescence. The luminescence was shown to be ‘switched on’ in the soft material after adjusting the pH of the solution in which the 1.Eu-incorporated film was immersed from alkaline to acid.