Anion Effects on Lanthanide(III) Tetrazole-1-acetate Dinuclear Complexes Showing Slow Magnetic Relaxation and Photofluorescent Emission

Three types of lanthanide complexes based on the tetrazole-1-acetic acid ligand and the 2,2′-bipyridine coligand were prepared and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analyses; the formulas of these complexes are [Ln2(1-tza)4(NO3)2(2,2′-bipy)2] (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5)), [Dy2(1-tza)4Cl2(2,2′-bipy)2] (6), and [Yb2(1-tza)4(NO3)2(2,2′-bipy)2] (7) (1-tza = tetrazole-1-acetate and 2,2′-bipy = 2,2′-bipyridine). They are dinuclear complexes possessing similar structures but different lanthanide(III) ion coordination geometries because of the distinction of peripheral anions (such as NO3– and Cl–) and the effect of lanthanide contraction. The variable-temperature magnetic susceptibilities of 1–6 were measured. Both DyIII complexes (5 and 6) display field-induced single-molecule magnet behaviors. Ab initio calculations revealed that the DyIII complex 6 possesses a more anisotropic DyIII ion in comparison to that in 5. The room-temperature photolumin...