A series of lanthanide complexes with different N-donor ligands: synthesis, structures, thermal properties and luminescence behaviors

Four novel lanthanide complexes, [Ln(2,4-DClBA)(3)(terpy)(H2O)]center dot H2O (Ln = Eu(1), Tb(2)); [Ln(2,4-DClBA)(3)(5,5'-DM-2,2'-bipy)(C2H5OH)](2) (Ln = Eu(3), Tb(4); 2,4-DClBA: 2,4-dichlorobenzoate; terpy: 2,2':6',2 ''-terpyridine; 5,5'-DM-2,2'-bipy: 5,5'-dimethyl-2,2'-bipyridine) have been synthesized via a conventional solution method at room temperature and structurally characterized by single crystal and powder X-ray diffraction. Complexes 1-2 exhibit mononuclear lanthanide architectures and each Ln(3+) ion is nine-coordinated adopting a distorted monocapped square antiprismatic molecular geometry, while complexes 3-4 exhibit binuclear lanthanide architectures in which each Ln(3+) ion is eight-coordinated adopting a distorted square antiprismatic molecular geometry. Mononuclear complexes 1-2 are stitched together via Cl-pi and hydrogen bonding interactions to form the 1D, 2D, 3D supramolecular structures. While complexes 3-4 are packed together through Cl-Cl, pi-pi, and hydrogen bonding interactions to form 1D, 2D supramolecular structures. Luminescence investigation reveals that complexes 1, 3 and 2, 4 display strong red and green emission respectively, showing that terpy and 5,5'-DM-2,2'-bipy can act as sensitizing chromophores, but the former is more effective. The IR, TG-DTG, and the heat capacities of complexes 1-4 were also measured.