The synthesis, spectroscopy, electrochemistry and photophysical properties of novel, sandwich europium(III) complexes with a porphyrin ligand bearing four pyrenyl groups in meso-positions

Novel, metal free porphyrins containing four pyrenyl groups in the meso-positions were used to provide novel, sandwich-type mixed tetrapyrrole europium double- and triple-deck complexes. The sandwich-type complexes together with the metal free porphyrin were characterized using electronic absorption, IR and H-1 NMR spectroscopy in addition to elemental analysis. The electrochemical behaviour of the sandwich complexes was investigated by cyclic voltammetry and differential pulse voltammetry in CH2Cl2, their photophysical properties were studied in comparison to those of the metal free porphyrin ligand. Fluorescence quenching observed was tentatively attributed to efficient and rapid energy transfer from the pyrenyl groups to porphyrin followed by electron transfer from porphyrin to phthalocyanine. (C) 2008 Elsevier Ltd. All rights reserved.