3.3 Voronoi-Dirichlet polyhedra of the triplet excited states

The Voronoi-Dirichlet polyhedra method allows one to reveal the features of the coordination environment of the central ion and its effect on intermolecular interactions. The VDP parameters can be used to identify the valence state of the ion, crystal-chemical stability, phase transitions of the first and second order, as well as the LC behavior of Ln(III) coordination compounds. They were calculated for the Eu(III) complexes in the optimized geometries of their ground and triplet excited states.[69,70] The resulting VDP shapes (Figure 5) are convex polyhedra with surfaces formed by planes passing perpendicularly through the midpoints of the Eu–O and Eu–N bonds.