Influence of Lewis Bases on the Mesogenic and Luminescent Properties of Homogeneous Films of Europium(III) Tris(β-diketonate) Adducts

A new series of neutral protomesogenic Eu-III tris(beta-diketonate) adducts with different Lewis bases have been synthesized. Only one of the complexes is liquid-crystalline and displays smectic A and nematic mesomorphism over a broad temperature range. Quantum-chemistry and small-angle X-ray scattering methods have permitted the evaluation of the influence of the structure of the Lewis base on the anisometry of Eu-III adduct molecules and their subsequent supramolecular organization. The structural features of the presented compounds allow the creation of vitrified optically isotropic and self-organized films with effective red luminescence. The luminescence spectra of aligned thin films of a liquid-crystalline Eu-III complex are also described.