New coordination polymers based on a V-shaped ligand and lanthanides: Structural description and symmetry-luminescence correlation using europium as a probe

We have synthesized new luminescent coordination polymers using 4,4׳-sulfonyldibenzoic acid (H2SDA) and several lanthanide ions by open crystallization in DMF. Three different 1-D structures were obtained, as determined by single-crystal X-ray diffraction: [La(η2-NO3)(μ-SDA)(DMF)3]n (1), [Sm(η2-NO3)(μ-SDA)(DMF)2·2DMF]n (3), [Ln(η2-NO3)(μ-SDA)(DMF)2·DMF]n (Ln = Eu (4), Dy (5), Ho (6), Er (7), Tm (8) and Lu (9)). A 2-D structure, [Er2(η2-SDA)3(DMF)(H2O)3·2DMF]n (10), was also obtained. The measured photophysical properties of these compounds seem to be interesting for applications (high lifetime, narrow line width and high degree of color purity). In addition, emission spectra, spontaneous emission coefficients (Arad and Anrad), and intensity parameters (Ω2 and Ω4), from spectroscopic data of Eu3+, were used to evaluate crystal stabilities. Differences in the spectra acquired before and after DMF removal clearly reflected the changes taking place in the ion environment.