Neighbour-sensitized near-infrared emission of new Nd(III) and Er(III) complexes with 1-(anthracene-2-yl)-4,4,4-trifluoro-1,3-butanedione

The photophysical properties of Nd(2-ATFB)(3) and Er(2-ATFB)(3) (2-ATFB = 1-(anthracene-2-yl)-4,4,4-trifluoro-1,3-butanedione) were investigated in various organic solvents. The Nd(III) and Er(III) complexes excited by near-UV light emitted near-infrared (NIR) emission from the lanthanide ions via energy transfer from the singlet excited states of the anthracene moiety to the resonance levels of the metal ions. The quantum yields of the sensitized NIR luminescence were estimated from the observed lifetimes of NIR luminescence. The efficiency of the sensitized NIR luminescence increased with increasing polarity of the solvent except for methanol: the OH group of methanol acted as a quencher. Quantum mechanical calculations were performed on the optimization of the model Gd(2-ATFB)(3) molecule and the configurational interaction singlet (CIS) using a coordinate 2-ATFB anion adapted from the optimized structure. The nature of the excited state of the 2-ATFB ligand as an energy donor in the complex was proposed.