Healable luminescent self-assembly supramolecular metallogels possessing lanthanide (Eu/Tb) dependent rheological and morphological properties.

Abstract

Herein we present the use of lanthanide directed self-assembly formation (Ln(III) = Eu(III), Tb(III)) in the generation of luminescent supramolecular polymers, that when swelled with methanol give rise to self-healing supramolecular gels. These were analyzed by using luminescent and (1)H NMR titrations studies, allowing for the identification of the various species involved in the subsequent Ln(III)-gel formation. These highly luminescent gels could be mixed to give a variety of luminescent colors depending on their Eu(III):Tb(III) stoichiometric ratios. Imaging and rheological studies showed that these gels prepared using only Eu(III) or only Tb(III) have different morphological and rheological properties, that are also different from those determined upon forming gels by mixing of Eu(III) and Tb(III) gels. Hence, our results demonstrate for the first time the crucial role the lanthanide ions play in the supramolecular polymerization process, which is in principle a host-guest interaction, and consequently in the self-healing properties of the corresponding gels, which are dictated by the same host-guest interactions.