A theoretical study of the energy-transfer process in [Eu subset of bpy.bpy.bpy](3+) cryptates: a ligand-to-metal charge-transfer state?

A complete theoretical model to calculate the luminescent properties of lan thanide coordination compounds is used to analyze the emission quantum yiel d of the [Eu subset of bpy.bpy.bpy](3+) and [Eu cbpy.bpy.bpy](3+) . 2H(2)O compounds. This theoretical model includes the calculation of the molecular structure, of the ligand electronic structure, of the ligand-lanthanide en ergy-transfer, of the temporal dependence of the ligand and lanthanide popu lations, which lead to the emission quantum yield, relative emission intens ity and lifetime of the emitting state. In the present case, this theoretic al approach was used to ascertain the presence of a ligand-to-metal charge- transfer (LMCT) state in these compounds. In addition, this approach has pr ovided indications of the location of the LMCT state as well as of the magn itudes of the energy-transfer rates involving this state. (C) 2000 Publishe d by Elsevier Science B.V.