A new family of lanthanide terpyridine nitrate complexes: Solvothermal syntheses, crystal structures and luminescent properties of [Ln(pytpy)(NO3)2(μ-OCH3)]2

The complexes [Ln(pytpy)(NO3)2(μ-OCH3)]2 (Ln = Eu(III), Tb(III), Dy(III), pytpy=4′-(n-pyridyl)-2,2′:6′,2″-terpyridine, n = 2, 3) were synthesized and characterized by IR, elemental analyses, UV–Vis and luminescent spectroscopy. Three complexes crystallized in monoclinic system, P21/n space group. Lanthanide ions are nine-coordinated by three nitrogen atoms from tridentate pytpy ligands, four oxygen atoms from two bidentate nitrate groups and two oxygen atoms from two methoxo groups, forming distorted tricapped trigonal prismatic geometries. The dimethoxo-bridges connect two metal ions in asymmetric fashion into dimeric structures with short Ln⋯Ln distances of 3.767(1), 3.740(1) and 3.720(1) Å for Eu(III), Tb(III) and Dy(III) complexes, respectively. Photoluminescence measurement indicates that 1 and 3 emit the characteristic luminescence of Tb(III) and Eu(III) ions in the solid state, respectively. The luminescent spectrum of Eu(III) complex in solvents was also investigated.