Structural and Luminescent Properties of Micro- and Nanosized Particles of Lanthanide Terephthalate Coordination Polymers

Abstract

Reaction in water between rare earth ions (Ln = Y, La-Tm, except Pm) and the sodium salt of terephthalic acid leads to a family of lanthanide-based coordination polymers of general formula [Ln2(C8H4O4)3(H2O)4] n with Ln = La-Tm or Y. The isostructurality of the compounds with the previously reported Tb-containing polymer is ascertained on the basis of their X-ray powder diffraction diagrams. The coordination water molecules can be reversibly removed without destroying the crystal structure for compounds involving one of the lighter lanthanide ions (La-Eu). For compounds involving one of the heavier lanthanide ions (Tb-Tm) or yttrium, a structural change occurs during the drying process. X-ray diffraction data show this new anhydrous phase corresponding to the linking of pairs of Er(III) ions through mu-carboxylate bridges. Porosity profiles calculated for the anhydrous phases of Tb(III) and Er(III) show the presence of channels with very small sections. The luminescent properties of all the compounds have been recorded and the two most luminescent polymers, namely, the europium- and the terbium-containing ones, have been studied in more detail. Tb(III)-containing compounds display large quantum yields, up to 43%. Polyvinylpyrrolidone nanoparticles doped with [Ln2(C8H4O4)3(H2O)4] n (Ln = Eu, Tb, Er) have also been synthesized and characterized. The encapsulation of the coordination polymers results in somewhat reduced luminescence intensities and lifetime, but the nanoparticles can be dispersed in water and remain unchanged in this medium for more than 20 h.

Color and Brightness Tuning in Heteronuclear Lanthanide Terephthalate Coordination Polymers

“…In this crystal structure, there is only one crystallographically independent Tb 3+ ion that occupies a 2i Wyckoff position. This is in agreement with previously reported luminescence studies in which only one metal ion environment with a pseudo C 4 symmetry was observed in the homonuclear [Eu 2 (bdc) 3 26] compound. Powder X-ray diffraction studies showed that in these compounds there is no long-range order or segregation.…”

“…These spectra also show that 312 nm is an efficient excitation wavelength for these compounds. [26] This is an interesting result as far as industrial applications are concerned, because this is a cheap commercially available irradiation wavelength. Therefore, the excitation wavelength was chosen as 312 nm in the following study.…”

“…For these reasons, numerous lanthanide-containing coordination polymers involving such ligands have been reported. Great attention has particularly been devoted to lanthanide terephthalate coordination polymers, [25][26][27][28][29][30] because the terephthalate rodlike ligand is nontoxic and commercially available at low cost (see Scheme 1). Scheme 1.…”

“…Lanthanide terephthalate coordination polymers with the general chemical formula [Ln 2 (bdc) 3 (H 2 O) 4 ] ϱ , for which Ln = La-Tm (except Pm) plus Y, [26] are of particular interest, because they can be almost quantitatively obtained as precipitated microcrystalline powders by mixing aqueous solutions of lanthanide chloride and sodium terephthalate at room temperature. Moreover, this crystalline phase (see Figure 1) is very stable, and it has been proven that heteronuclear compounds with the general chemical formula x i = 2 [56] and for www.eurjic.org…”

Thermo-stable Lanthanoid Coordination Nanoparticles Composed of Luminescent Eu(III) Complexes and Organic Joint Ligands Using Micelle Techniques in Water

“…6 Thermal stability of the luminescent plastic materials are required that Preparations of lanthanide coordination nanoparticles assisted with surface stabilizers have been reported. 14,15 Kimizuka has also successfully reported lanthanide 4 coordination nanoparticles using supramolecular networks. 16 We here focused on characteristic formation of organo-nanoparticles using micelle technique in liquid media, such as preparation of nano scaled organic compounds.…”