Rare Earth Metal Oxalatophosphonates: Syntheses, Structure Diversity, and Photoluminescence Properties

Abstract

Hydrothermal reactions of N-piperidinomethane-1-phosphonic acid (H 2 pmp) and oxalate anion with trivalent rare earth metal ions yielded 13 rare earth oxalatophosphonates with three closely related structural types, ranging from two-dimensional (2D) networks to three-dimensional (3D) frameworks. They are formulated as [Ln 3 (Hpmp) 5), Sm (6), Eu (7), Tb (8), Dy (9), Ho (10), Er (11), Yb (12), Y (13), type II structure], andTheir structures were characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), infrared (IR) spectroscopy, elemental analysis (EA), and thermogravimetric analysis (TGA), except that the structures of compounds 2 and 3 were confirmed by PXRD, IR, and EA. The effects of reaction conditions including pH value, reaction temperature, counterion, and stoichiometry of the starting materials on the structures have been discussed. Furthermore, the solid-state photoluminescence properties of the Eu (2 and 7) and Tb (3 and 8) compounds have been measured at room temperature. The two types of Eu and Tb compounds display intense red and green luminescence emissions, respectively, with lifetimes at the millisecond order.

An erbium-organic polymer incorporating 2-(hydroxyl)-6-methylisonicotinic and oxalate coligand with 63 topology

“…This is nei ther similar to other reported transition metal com plexes, in which the central ions are connected through ambient oxalate ligands to form honeycomb homometallic layers [15], nor it is different from the lanthanide complexes containing oxalatophospho nates, in which six Ln 3+ ions were linked through six oxalate anions into a netlike {Ln(C 2 O 4 ) n } 24 member ring in a layer [16]. However, when the binuclear Er 2 unit doubly connected through carboxylic group is re garded as a three connected node, the whole structure can be described as a uninodal 3 connected corrugat ed network, with 3, 6 hcb topology [17], and the point symbol is 6 3 , as shown in Fig.…”

Optimization of the process of obtaining RE 2 O 3 from xenotime using statistical design

“…The concentration of precipitant solution used for conversion of the oxalates to oxides of rare earths was 80 g/mL, thus obtaining a yield of 98.25%. Oxalic acid has great selectivity, allowing for the attainment of rare earth oxalates which are insoluble in the reaction medium used [21][22][23]. According to the statistical design, we obtained oxalate by calcination from XRD pattern in Fig.…”

“…The behavior of the mixed rare earth oxide observed in the XRD pattern suggested that the constituents of the same metals, as oxides, form a solid solution of yttrium matrix due to the similarity of the rare earths (atomic radius, ionic radius, electronegativity and valence). The peaks were slightly displaced with respect to the rare earth oxides with the highest concentration found in xenotime [22][23][24][25][26]. Chemical analysis by atomic emission spectroscopy by induced plasma (Table VIII) [8].…”

Syntheses, structure and photoluminescent properties of lanthanide oxalatosulfocarboxylate coordination polymers

“…This so called "antenna effect" has been well documented for lanthanide complexes based on β-diketonates, polyazine ligands, microcycle polyamines and aromatic carboxylate ligands [6][7][8][9][10][11][12][13][14][15][16][17][18]. Our research group has also reported some luminescent lanthanide complexes constructed from phosphonate, sulfonate, oxalate and carboxylate ligands in recent years [19][20][21]. The oxalate ligand (H 2 ox) chelates to Ln ions and forms a series of complex lanthanide oxalates, from the commonly known Ln(C 2 O 4 ) n (n = 1-4) moieties to the rarely observed Ln(C 2 O 4 ) 5 units [22,23].…”