Luminescent lanthanide complexes with 4-acetamidobenzoate: Synthesis, supramolecular assembly via hydrogen bonds, crystal structures and photoluminescence

Four new luminescent complexes, namely, [Eu(aba)2(NO3)(C2H5OH)2] (1), [Eu(aba)3(H2O)2]·0.5 (4, 4′-bpy)·2H2O (2), [Eu2(aba)4(2, 2′-bpy)2(NO3)2]·4H2O (3) and [Tb2(aba)4(phen)2(NO3)2]·2C2H5OH (4) were obtained by treating Ln(NO3)3·6H2O and 4-acetamidobenzoic acid (Haba) with different coligands (4, 4′-bpy=4, 4′–bipyridine, 2, 2′-bpy=2, 2′-bipyridine, and phen=1, 10-phenanthroline). They exhibit 1D chains (1–2) and dimeric structures (3–4), respectively. This structural variation is mainly attributed to the change of coligands and various coordination modes of aba molecules. Moreover, the coordination units are further connected via hydrogen bonds to form 2D even 3D supramolecular networks. These complexes show characteristic emissions in the visible region at room temperature. In addition, thermal behaviors of four complexes have been investigated under air atmosphere. The relationship between the structures and physical properties has been discussed.

Graphical abstractStructure variation of four complexes is attributed to the change of coligands and various coordination modes of aba molecules. Moreover, they show characteristic emissions in the visible region. Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Auxiliary ligands have played the crucial roles on the structures of the resulting complexes. ► Isolated structure units are further assembled via H-bonds to form supramolecular networks. ► These solid-state complexes exhibit strong, characteristic emissions in the visible region.