ER MAGNETIC AND LUMINESCENT COMPOUNDS
The development of the multifunctionality approach with lanthanoid-based materials has proven to be a challenge. Lanthanides have unique properties associated parity-forbidden 4f–4f transitions and large magnetic moments of partially filled f-levels making them appealing for dual-function (optical–magnetic) materials. In this context a new Er3+ homodinuclear complex bridged by an aromatic molecule, [Er2(nd)6(μ-bpm)], (nd= 2,4-nonanedione, bpm= 2,2′-bipyrimidine) was prepared. The bridging ligand bipyrimidine allows indirect exchange between Er magnetic moments. This compound displays NIR luminescence when excited in the UV region (360-375 nm), after a ligand-to-lanthanide energy transfer and presents slow relaxation of magnetization only under a small static field. Some persistence of a relaxation by quantum tunnelling via the ground state and the first excited state could be explained by the lack of a perfect axial g-tensor, and thus by a small mixing between the ground and excited states, as elucidated by the ab-initio calculations.