The first example of tetranuclear lanthanide complexes with 2-sulfobenzoate and 1,10-phenanthroline

Abstract Four novel complexes {[Ln 2 (2-SB) 3 (phen) 3 (H 2 O) 2 ] ·  n H 2 O} 2 (Ln = Sm ( 1 ), n  = 3; Ln = Eu ( 2 ), n  = 2; Ln = Tb ( 3 ), n  = 2; and Ln = Dy ( 4 ), n  = 2.5; 2-SB = 2-sulfobenzoate, phen = 1,10-phenanthroline), were synthesized by hydrothermal reactions and characterized using single-crystal X-ray diffraction, thermogravimetric analyses and luminescence spectroscopy. In the four complexes, there are two types of Ln(III) ion coordination environments. Ln(III) ions are connected together through 2-SB ligands via μ2-, η3- and η2-coordination modes, resulting in a tetranuclear molecule with central symmetry, indicating novel structural features. The emission spectra of the four complexes indicate the typical luminescence characteristics of the Sm(III) for 1 , Eu(III) for 2 , Tb(III) for 3 , and Dy(III) ions for 4 , respectively.