A Series of Novel Lanthanide(III) Trisulfonates Based on Dinuclear Clusters

Hydrothermal reactions of lanthanide(III) salts with sodium 2,4,6-trisulphonate, Na3L(H2O)(3), (1) (L = 2,4,6-trisulfo-C6H2-OH) and 1,10-phenanthroline (phen) led to seven new lanthanide(III) sulfonate hybrids, namely, La(L)(phen)(H2O)(3)center dot phen center dot 3H(2)O (2), Ln(2)(L)(2)(phen)(3)(H2O)(5)center dot 2phen center dot 8.5H(2)O (Ln = Pr, 3; Nd, 4), Ln(2)(L)(2)(phen)(2)(H2O)(4)center dot 2phen center dot 8H(2)O (Ln = Eu, 5; Gd, 6; Th, 7), and Nd(L)(phen)(H2O)center dot phen center dot H2O (8). 1 features a three-dimensional (3D) network in which the sodium(I) ions are interconnected by chelating and bridging trisulphonate ligands. 2-7 contain [Ln(2)(L)(2)(phen)(2)] dinuclear clusters which are further assembled into 3D supramolecular networks via very weak hydrogen bonds and aromatic packing interactions. 8 features a one-dimensional chain in which two neighboring Nd2O2 dinulear cluster units are further bridged by a pair of sulfonate ligands. 2, 3, 6, and 7 display a broad and strong ligand-centered luminescent emission band in the blue-light region, whereas 4, 5, and 8 exhibit very strong emission bands characteristic of the corresponding lanthanide(III) ions. Magnetic measurements indicate that there is antiferromagnetic interactions between magnetic centers in 3-6 and 8 but ferromagnetic interactions in 7.