Quantum-chemical study of luminescence efficiency and excited state structures of some mesogenic europium(III) complexes with β­diketones and Lewis bases

Abstract

Metal-containing liquid crystals and, in particular, Ln(III) complexes with unique structural, liquid-crystalline (LC), optical and magnetic properties are the examples of currently relevant multifunctional materials. Indirect structure-property relationships, their dependence on various factors and insufficiently studied determinant physicochemical mechanisms complicate the application of mesogenic Ln(III) complexes. While Ln(III) and ligand environment are selected prior to the synthesis, structural features of coordination polyhedra, especially upon photoexcitation, are not uniquely defined. Therefore, this work is focused on the development of theoretical approaches to the creation of multifunctional materials based on highly luminescent mesogenic Eu(III) complexes with β­diketones and Lewis bases. The relationships between their structure, parameters of Voronoi-Dirichlet polyhedra, luminescence efficiency and LC properties were considered. The calculated excited states and intramolecular energy transfer rates were used to determine intramolecular energy transfer channels. It was shown that their LC behavior is mainly defined by the ligand environment, while optical properties can also be determined by the coordination polyhedra.