Enhanced TbIII-centered Luminescence due to Elongated Methylene Arms of Tripodal Schiff Base Ligand

Ln(III)-tripodal Schiff base complex (TbLtrpn)-L-III was prepared, in which the three arms of the ligand were extended by one methylene based on the tris(2-aminoethyl)amine in (TbLtren)-L-III. (TbLtrpn)-L-III showed enhanced TbIII-centered luminescence compared to TbIIILtren. Crystallographic analysis revealed that the symmetry of the seven-coordination environment of the Tb-III center in (TbLtrpn)-L-III was diminished compared to that in (TbLtren)-L-III, resulting in the increased radiative transition rate and/or decreased back energy transfer rate and, thus, the increased luminescence.

Automated summary

The Ln(III)-tripodal Schiff base complex (TbLtrpn)-L-III was prepared, with the three arms of the ligand extended by one methylene compared to (TbLtren)-L-III. The enhanced TbIII-centered luminescence in (TbLtrpn)-L-III was attributed to the diminished symmetry of the seven-coordination environment of the Tb-III center, leading to an increased radiative transition rate. This provides a new insight for improving the luminescence properties of lanthanide metal complexes.