Synthesis, characterization and photophysical studies of novel pyrene labeled ruthenium (II) trisbipyridine complex cored dendrimers

Abstract

Two new bipyridine ligands containing, respectively, two and four pyrene units were prepared. Theobtained compounds were employed to synthesize new pyrene labeled ruthenium (II) trisbipyridinecomplex as well as a pyrene labeled ruthenium (II) trisbipyridine cored dendrimer. The obtainedbipyridine ligands and the ruthenium complexes were characterized by NMR spectroscopy and MALDI-TOF mass spectroscopy. The optical and photophysical properties of the luminescent macromoleculeswere studied by absorption andfluorescence spectroscopy. It was noticed that the absorption spectra ofthe obtained complexes correspond to the sum of the absorption spectra of their components, whichindicates a lack of interaction in the ground state. Efficient energy transfer was observed from pyreneunits to the metal complex core resulting in the observation of the characteristic ruthenium bipyridineemission band upon excitation at the pyrene absorption wavelength. Moreover, efficient protection tooxygen quenching was remarked in thefirst generation dendrimer.