Formation of molecular glasses of (N-acylalaninato)europium(III) complexes and the luminescence properties

Tris(N-octanoyl-DL-alaninato)europium(III) (Eu(oct-ala)(3)) was newly prepared and it was found that the complex takes a stable glassy state by an evaporation of methanol from the solution, whereas tris(octanoato)europium(III) (Eu(octnt)(3), i.e. europium soap) does not easily take a purely vitrified state. The luminescence intensity was larger and the spectrum was simpler in the glassy state than those in the devitrified state. It is characteristic that an addition of 2,2'-bipyridine (bpy) or 4,4'-dinonyl-2,2'-bipyridine (dnbpy) to Eu(oct-ala)3 increases the luminescence intensity both in solutions and in solids and that Eu(octnt)3 becomes to take a stable glassy state by an addition of bpy. (c) 2005 Elsevier B.V. All rights reserved.