Self-Assembly of a Tripodal Terpyridine Based Ligand with Luminescent Lanthanide Ions in Solution and Soft Material

Abstract

The tripodal 1,3,5-benzene tricarboxamide (BTA) ligand functionalized with terpyridine (1) is used to self-assemble with Ln(III) ions (Ln = La, Sm, Eu, Gd, Tb, Yb, and Lu) in solution and within soft material (supramolecular metallogels). Stability constants for 1:1 and 3:2 (M:L) assemblies formed in MeOH are determined using nonlinear regression analysis of UV–vis absorption and emission titrations revealing a parabolic relationship between the binding constants values and the ionic radii of Ln(III) ions. The formation of gels using ligand 1 in MeOH-H₂O at 0.6 wt.% and their modification, by diffusing the Ln(III) ions through them is described. The latter leads to both crosslinking of already self-assembled ligands, as well as modulating their physical properties as demonstrated by photophysical, rheological, and morphological studies leading to significant changes in the in situ morphology.