Excited state energy transfer from terminal β-diketonate ligands to a central boron dipyrrin (Bodipy), mediated by lanthanide (III) metals

Abstract

A new boron-dipyrromethene (Bodipy) dye with phenanthro-fused groups at the β-pyrrole positions is described. The π-extended pyrrole units result in intense red-shifted absorption and emission in the visible region of the spectrum. The phenathroline groups are incorporated to allow for coordination of Ln(III) β-diketonates giving the first examples of bis-Ln(III)-Bodipy complexes (where Ln = Eu and Tb). Electronic spectroscopy of the disubstituted Ln(III)-Bodipy complexes reveal β-diketonate charge transfer in the ultraviolet region of the spectrum and π π * transitions associated with the Bodipy core. Upon excitation of the terminal antenna β-diketonate ligands, within the ultraviolet region, emission of the Bodipy core is observed with no evidence of Ln(III) emission; suggesting energy transfer from the antenna ligands to the lanthanide ion to the Bodipy core (An → Ln(III) → Bodipy).