An erbium(III)-based NIR emitter with a highly conjugated β-diketonate for blue-region sensitization

The sensitization of lanthanide complexes in the visible region is of particular interest for practical applications such as labeling, biological analysis and optoelectronics. A visible-light sensitized Er3+ complex based on the use of a highly conjugated β-diketonate (1,3-di(2-naphthyl)-1,3-propanedione, Hdnm) and 5-nitro-1,10-phenanthroline (5NO2phen) as an ancillary ligand, [Er(dnm)3(5NO2phen)], has been synthesized, fully characterized and its photophysical properties have been investigated. Suitably expanded π-conjugation in the complex molecule makes the excitation window red-shifted to the visible region (up to 550 nm). Efficient energy transfer by antenna effect results in 1.53 μm emission from the Er3+ ion.