Sandwich-type lanthanide(III) complexes of a tetraiminodiphenol macrocyclic ligand derived from 4-methyl-2,6-diformylphenol and 1,3-diaminopropane: structure, NMR and luminescence

The macrocyclic ligand cation [H2LH2]2+ produces the lanthanide(III) sandwich complexes [Ln(LH2)2]3+ with a folded configuration and the luminescence intensity of [Eu(LH2)2]3+ increases progressively on being deprotonated to [Eu(LH2)(LH)]2+ and [Eu(LH)2]+.69