Ion size dominated 1D and 2D Salen lanthanide coordination complexes and their luminescence

Lewis acid/base addition between Ln(NO3)3 · 6H2O (Ln = Pr, Nd, Sm, Eu, Tb and Lu) and H2salen [H2salen = N,N′-ethylenebis(salicylideneimine)] gives rise to an array of coordination polymeric structures. Crystal structural analysis reveals that Salen effectively functions as a bridging ligand in these compounds. The size of the lanthanide ions controls the structures of these Salen lanthanide complexes. Two representative structures with one dimensional and two dimensional topologies, viz. [Pr(H2salen)(NO3)3(CH3OH)2]n (1) and [Ln(H2salen)1.5(NO3)3]n [Ln = Pr (2), Nd (3), Sm (4), Eu (5), Tb (6) and Lu (7)] are reported. Luminescent spectra of complexes 4 and 5 exhibit characteristic metal-centered emission lines. However, the characteristic luminescence of the terbium(III) ion is not observed either in solution or in the solid state of complex 6.

Graphical abstractTwo representative structures, viz. [Pr(H2salen)(NO3)3(CH3OH)2]n (1) and [Ln(H2salen)1.5(NO3)3] [Ln = Pr (2), Nd (3), Sm (4), Eu (5), Tb (6) and Lu (7)] [H2salen = N,N′-ethylenebis(salicylideneimine)] are described and discussed. Luminescent spectra of complexes 4 and 5 exhibit characteristic metal-centered fluorescence.Figure optionsDownload full-size imageDownload as PowerPoint slide