Synthesis, Structures and Luminescence Properties of Metal-Organic Frameworks Based on Lithium-Lanthanide and Terephthalate

Luminescent lanthanide mixed N-phthaloylglycinate and terephthalate coordination polymers: Structural and optical properties

A new class of lanthanide mixed-carboxylate ligands compounds with formula {[Ln2 (phthgly)4 (bdc)(H2 O)6 ]·(H2 O)4 }∞ , labelled as Ln3+ : Eu (1) and Gd (2) coordination polymers (CP) were synthesized under mild reaction conditions between lanthanide nitrate salts and a solution of N-phthaloylglycine (phthgly) and terephthalic (bdc) ligands. The (1) and (2) coordination polymers were formed by symmetric binuclear units, in which phthgly and bdc carboxylate ligands are coordinated to the lanthanide ions by different coordination modes. Surprisingly, all organic ligands participate in hydrogen bonding interactions, forming an extremally rigid crystalline structure. The red narrow emission bands from the 5 D0 →7 FJ transitions of the Eu3+ ion show a high colour purity. The intramolecular energy transfer process from L→Eu3+ ion has been discussed. The experimental intensity parameters (Ω2,4 ) reflect lower angular distortion and polarizability of the chemical environment around the metal ion compared with other Eu3+ compounds reported in the literature. This novel class of coordination polymer offers a more attractive platform for developing luminescent functional materials for different applications.

Heteronuclear Bimetallic Complexes with 3d and 4f Elements

Three heteronuclear bimetallic complexes [Cu(MeOH)(L)Ln(NO3)3] (1-Ce; Ln = Ce, 1-Pr; Ln = Pr, and 1-Nd; Ln = Nd) were prepared using H2L (1,3-bis[(3-methoxysalicylidene)amino]-2,2-dimethylpropane) in methanol, affording the complexes as green crystalline materials. These can be prepared in a one-pot synthesis from 2,2-dimethylpropan-1,3-diamine, o-vanillin, copper(II) nitrate, and Ln(III) nitrate (Ln = Ce, Pr, Nd). X-ray crystallography, high-resolution mass spectrometry, and UV-vis spectroscopy were used to characterize the bimetallic complexes. All three complexes showed the copper center adopting a five-coordinate square pyramidal geometry and the lanthanoid cation adopting a ten-coordinate geometry.

Synthesis and characterizations of YZ-BDC:Eu3+,Tb3+ nanothermometers for luminescence-based temperature sensing

In the present work, nanothermometers based on amorphous zirconium metal–organic frameworks co-doped with rare-earth ions (YZ-BDC:Eu³⁺,Tb³⁺ nanothermometers) with sizes of about 10–30 nm were successfully synthesized via a microwave-assisted hydrothermal method at 120 °C for 15 min. The determined BET surfaces area, total pore volume and average pore diameter were ∼530 m² g⁻¹, 0.45 cm³ g⁻¹ and 3.4 nm, respectively. Based on Fourier transform infrared spectroscopy (FTIR) and simultaneous thermal analysis (STA) results, the formation process of carboxylic acid salts and the molecular formula of the samples have been proposed. The thermometric properties of Zr-BDC:Eu³⁺,Tb³⁺ nanothermometers and their Y³⁺ ion co-doped counterparts (YZ-BDC:Eu³⁺,Tb³⁺) measured in the 133–573 K temperature range were compared. Moreover, the temperature-dependent CIE(x, y) chromaticity coordinates and emission color of the samples were also determined. As the temperature increased from 133 to 573 K, the emission color of Zr-BDC:Eu³⁺,Tb³⁺ nanothermometers without the presence of Y³⁺ ions changed from orange to red, while for YZ-BDC:Eu³⁺,Tb³⁺ nanothermometers, the emission color changed from yellow to orange, due to the strong effect of the presence of Y³⁺ ions on the luminescence intensity of Eu³⁺ and Tb³⁺ ions. The maximum relative sensitivity (S_Rmax) in both materials was close to 0.5%/K, however, the temperature range of their occurrence was significantly shifted toward higher temperatures due to doping with Y³⁺ ions. The obtained results showed that doping with Y³⁺ ions not only enables the modulation of the useful temperature range with high relative sensitivity, but also provides improved thermal stability.

In the present work, nanothermometers based on amorphous zirconium metal–organic frameworks co-doped with rare-earth ions (YZ-BDC:Eu³⁺,Tb³⁺) with sizes of about 10–30 nm were successfully synthesized via a microwave-assisted hydrothermal method at 120 °C for 15 min.

Eu-Doped layered yttrium hydroxides sensitized by a series of benzenedicarboxylate and sulphobenzoate anions

A series of new Eu-doped layered yttrium hydroxides intercalated with various organic dianions having similar molecular structure (dicarboxylates and sulphobenzoates) were synthesized.