Hydrothermal synthesis, structure and luminescent properties of one-dimensional lanthanide benzenedicarboxylates, [M(NO₃)M₂(C₁₂H₈N₂)₂][(C₈H₄O₄)₄]·H₂O, (M = La, Pr), possessing infinite M–O–M linkages

A hydrothermal reaction of a mixture of M(NO₃)₃, 1,2-dicyanobenzene, 1,2-benzenedicarboxylic acid (1,2-BDC), 1,10-phenanthroline and piperazine gave rise to a new compound, [M(NO₃)M₂(C₁₂H₈N₂)₂][(C₈H₄O₄)₄]·H₂O, (M = La, I and Pr, II). The structure is built up from the connectivity of MO_n polyhedra by sharing an edge or face. The metal atoms are coordinated by 1,10-phenanthroline or nitrate groups along with the phthalates resulting in an infinite one-dimensional M–O–M chain. The crystal structure is stabilized by π⋯π and CH⋯π interactions. Our preliminary investigations of the Eu³⁺/Tb³⁺ doped samples (in place of La³⁺), indicate that interesting red/pink or green luminescence can obtained by excitation at 252 nm. The luminescence behavior probably results from the ligand-sensitized metal-centered emission.