Influence of Structural Anisotropy on Mesogenity of Eu(III) Adducts and Optical Properties of Vitrified Films Formed on their Base

A new series of europium adducts with the general formula Eu(CPDk(3-cnH2n+1)),Phen, where CPDk(3-CnH2n+1) denotes beta-diketones and Phen is 1,10-phenanthroline, was synthesized. The obtained mesogenic complexes were heated to the temperatures of the isotropic liquid state and then cooled. The complexes having short CH3 and C2H5 substituents crystallized upon cooling, and the complexes with longer substituents from C3H7 to C6H13 underwent a glass transition with the formation of optically transparent amorphous films. Inside the series the complexes with C7H15 and C8H17 substituents exhibited a unusual smectic C mesomorphism for lanthanidomesogens. On the basis of quantum-chemical simulations and the results of small-angle X-ray scattering the dependence between the anisotropy of Eu(III) complexes with various ligand environments and their supramolecular organization was found. The synthesized Eu(III) complexes in the solid state show intense red photoluminescence upon irradiation by ultraviolet light (lambda(max) - 337 nn).