Towards materials with planned properties: dinuclear f-f helicates and d-f non-covalent podates based on benzimidazole-pyridine binding units

Abstract

We have taken advantage of self-assembly processes associated with the induced fit concept to design multidentate segmental ligands based on substituted benzimidazole-pyridine moieties which lead to the selective formation of stable luminescent mononuclear lanthanide complexes, dinuclear f-f helicates and non-covalent d-f lanthanide podates. The influence of the various substituents on the stability and quantum yield of the non-covalent edifices is discussed. It is demonstrated that replacement of one benzimidazole moiety by a carboxamide group enhances considerably the luminescent properties of the supramolecular light-converting devices. Moreover, the introduction of a non-covalent d-block tripod (ZnII, FeII) into the organic ligand increases the thermodynamic stability and the selectivity of the complexation process. The lanthanide podates containing a non-covalent FeII tripod display a spin crossover behavior in the temperature range 300–360 K leading to new materials with tunable magnetic properties. Finally, the multi-component self-assembly leading to the heterodinuclear non-covalent d-f podates is discussed together with the 1H NMR characterization of intricate lanthanide complexes.