Columnar Mesophases in Hybrid Organic−Inorganic Supramolecular Aggregates: Liquid Crystals of Fe, Cr, Mo, and W at Room Temperature, Built from Triazines and Metalloacid Complexes

Hybrid organic−inorganic supramolecular aggregates displaying liquid crystal properties at room temperature have been synthesized by linking equimolar amounts of 2,4,6-triarylamino-1,3,5-triazine and metallo-acids [Fe(CO) 4 (CNC 6 H 4 CO 2 H)] and [M(CO) 5 (CNC 6 H 4 CO 2 H)] (M = Cr, Mo, W) through hydrogen bonding formation. The starting metalloacids and their triazine aggregates display photoluminescent properties in solution and in the condensed phase (crystalline or glassy) at low temperature, but not in the mesophase. The mesophase produced by the supramolecular hybrid aggregates is always columnar hexagonal (Col h ), corresponding to a columnar packing of 1:1 triazine-metalloacid supramolecules. The stability range of the columnar hexagonal mesophases is large, and the clearing temperatures decrease very regularly in the order Fe > Cr > Mo > W. All the supramolecular species show high thermal stability, even in the isotropic state.