A new family of lanthanide coordination polymers based on 3,3′-[(5-carboxylato-1,3-phenylene)bis(oxy)]dibenzoate: synthesis, crystal structures and magnetic and luminescence properties

Abstract

Six two-dimensional (2D) coordination polymers (CPs), namely, poly[{μ5-3,3-[(5-carboxylato-1,3-phenylene)bis(oxy)]dibenzoato-κ6 O 1:O 1′:O 3,O 3′:O 5:O 5′}bis(N,N-dimethylformamide-κO)lanthanide(III)], [Ln(C21H11O8)(C3H7NO)2] n , with lanthanide/Ln = cerium/Ce for CP1, praseodymium/Pr for CP2, neodymium/Nd for CP3, samarium/Sm for CP4, europium/Eu for CP5 and gadolinium/Gd for CP6, have been prepared by solvothermal methods using the ligand 3,3′-[(5-carboxy-1,3-phenylene)bis(oxy)]dibenzoic acid (H3cpboda) in the presence of Ln(NO3)3. The complexes were characterized by single-crystal X-ray and powder diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis (TGA). All the structures of this family of lanthanide CPs are isomorphous with the triclinic space group P\overline{1} and reveal that they have the same 2D network based on binuclear LnIII units, which are further extended via interlayer C—H...π interactions into a three-dimensional supramolecular structure. The carboxylate groups of the cpboda3− ligands link adjacent LnIII ions and form binuclear [Ln2(RCOO)4] secondary building units (SBUs), in which each binuclear LnIII SBU contains four carboxylate groups from different cpboda3− ligands. Moreover, with the increase of the rare-earth Ln atomic radius, the dihedral angles between the aromatic rings gradually increase. Magnetically, CP6 shows weak antiferromagnetic coupling between the GdIII ions. The solid-state luminescence properties of CP2, CP5 and CP6 were examined at ambient temperature and CP5 exhibits characteristic red emission bands derived from the Eu3+ ion (CIE 0.53, 0.31), with luminescence quantum yields of 22%. Therefore, CP5 should be regarded as a potential optical material.

Fluorescence-Based Aqueous Phosphate Sensing Using Eu(cpboda)(DMF)2

“…Figure 1 shows the chemical structure of the phosphor. Note that this material was previously made and structurally characterized by Yang et al for a different application [35] and our structural results are consistent with theirs.…”

“…Similarly, we perform multipeak fitting of the emission spectra and report the peak locations and transitions assignments in Table 1. Given the observation of the 5 D 0 → 7 F 0 transition, we know that the Eu ions occupy sites with a C N symmetry [36], which we further refine to either C 1 or C i symmetry as the crystal structure of the Tb version of this complex was found to be triclinic [35]. To complete our analysis of Eu(cpboda)(DMF) 2 's photoluminescence properties, we analyzed the emission spectra using JOES software (v2.7) [37] to compute the phosphor's Judd-Offelt parameters and its estimated quantum efficiency.…”

“…reagent from Avantor (Allentown, PA, USA). We prepared Eu(cpboda)(DMF) 2 using hydro-solvothermal synthesis [19,35] by dissolving a mixture of H3cpboda, Eu(NO 3 ) 3 •6H 2 O and NaOH in 14.0 mL of DMF-H 2 O (v/v = 5/2) solution and stirring in a high pressure reaction vessel with 25 mL PTFE cup and cover for hydro-solvothermal synthesis. We placed the PTFE cup and cover in the reaction vessel and the secondary stainless-steel lid was hand-tightened and placed into a preheated oven at 140 • C for 72 h, followed by a natural cool down to room temperature.…”