Cross-Linking the Fibers of Supramolecular Gels Formed from a Tripodal Terpyridine Derived Ligand with d-Block Metal Ions

The tripodal terpyridine ligand, L, forms 1D helical supramolecular polymers/gels in H2O-CH3OH solution mediated through hydrogen bonding and pi-pi interactions. These gels further cross-link into 3D supramolecular metallogels with a range of metal ions (M) such as Fe(II), Ni(II), Zn(II), and Ru(III); the cross-linking resulting in the formation of colored or colorless gels. The fibrous morphology of these gels was confirmed using scanning electron microscopy (SEM); while the self-assembly processes between L and M were investigated by absorbance and emission spectroscopy from which their binding constants were determined by using a nonlinear regression analysis.