Syntheses, Crystal Structures, and Solid-State Photoluminescence Properties of Heterotrinuclear Zn2Ln (Ln: La, Sm, Eu, Tb) Complexes Derived from 1,4-Diaminobutane-Based N2O4 Compartmental Ligand

Abstract The one-pot reaction of N,N’ -bis(3-methoxysalicylidene)-1,4-diaminobutane (MeOsalbnH 2 ), zinc(II) perchlorate, and lanthanide(III) acetate by a molar ratio of 2:2:1 affords a heterotrinuclear Zn 2 Ln (Ln: La, Sm, Eu, Tb) complex formulated as [Ln(CH 3 COO) 2 {Zn(MeOsalbn)} 2 ]ClO 4 . In this complex, the central Ln(III) atom is bridged by two {Zn(MeOsalbn)} units and two acetate ligands to form ten-coordination environment. Each Zn(II) atom is coordinated by MeOsalbn 2− through the N 2 O 2 site and one oxygen atom from the bridging acetate to afford a five-coordination geometry. In the crystalline state at room temperature, the La(III) complex exhibits a bright blue fluorescence, while the Sm(III) complex shows a reddish-orange colored f-f photoluminescence via an energy transfer from the T 1 state localized on the {Zn(MeOsalbn)} units to the acceptor level of the central Sm(III) ion. The results of TD-DFT calculations show that the lowest excited singlet state or triplet state involved in photoluminescence of the La(III) or Sm(III) complex has some intramolecular charge-transfer (CT) character from the phenoxo or methoxy groups to the imino groups in the coordinated MeOsalbn 2− moieties.