Synthesis, Crystal Structure, and Visible Light Sensitized Red Luminescence of a Novel Salen-Bridged Pentanuclear Eu-Na Complex

The europium complex 1 ([Eu2Na3(bsalen)2(L)2(CH3O)(NO3)2] ⋅ 3H2O) with unusual trigonal bipyramid-shaped core [Na3Eu2] has been formed via the reaction of Eu(NO3)3 with N,N'-bis(3-methoxy-salicylidene)-ethylenediamine (bsalen2– ligand), 2-hydroxy-4-methoxybenzophenone (HL) and NaOH in the ratio of 1 : 1 : 1 : 3.5 in methanol. Crystal structure reveals that each Eu(III) ion is encapsulated in the inner cavity of bsalen2– ligand. Photoluminescence (PL) measurement results show that the europium complex exhibits intense red emission (611 nm) under blue light excitation (417 nm) with quantum efficiency of 16.9% and lifetime of 1.02 ms.