Supramolecular Arene-Ruthenium Metallacycle with Thermotropic Liquid-Crystalline Properties.

Functionalization of 1,4-di(4-pyridinyl)benzene with poly(arylester) dendrimers bearing cyanobiphenyl end-groups gives a bidentate dendromesogenic ligand (L) that exhibits thermotropic liquid-crystalline properties. Combination of the diruthenium complex [Ru2(p-cymene)2(donq)][DDS]2 (M) with L, by coordination-driven self-assembly, affords the discrete and well-defined metallacycle M2L2. Like L, this supramolecular dendritic system displays mesomorphic properties above 50 °C. Both compounds L and M2L2 show smectic phases, characterized by a multilayered organization of the multiple components.