Theoretical design of highly luminescent europium (III) complexes: A factorial study

In this work, the design of europium (III) complexes exhibiting high quantum yield was accomplished by a systematic study using factorial design and the Sparkle/AM1 model. Eight new complexes derived from the Eu(acac)3.o-phen complex (acac = acetylacetonate acid and o-phen = 1,10-phenantroline) were generated through a 23 full factorial design. The ground state geometries of the eight new complexes were predicted using the Sparkle/AM1 model. The singlet and triplet excited levels were calculated using the INDO/S-CIS method, implemented in ZINDO program. Energy transfer rates and quantum yields for each one of the new complexes were calculated using the theoretical model based on the theory of the transitions 4f-4f (Spectrochim. Acta Part A, 1998, 54, 1593). The results strongly suggest that the europium complexes with β-diketone ligands might display a quantum yield increment when strongly electron acceptor groups are added to one of the β-diketone extremities and strongly electron donor groups are added to the opposite side. From the factorial design proposed in this work it was possible to project complexes with quantum yields up to 70%.