Lanthanide( iii ) oxalatophosphonates: syntheses, crystal structures and luminescence properties

4 L3) afforded six new layered metal phosphonates, namely, [Zn 3 (HL1) 3 ]· 3H 2 O (1), [Zn(HL1)]·CH 3 COOH (2), [Zn(H 2 L2)] (3), [Mn(H 3 L2) 2 ] (4), [Mn(H 3 L3) 2 ] (5), and [Zn(H 2 L3)]·H 2 O ( 6). Compounds 1−6 are characterized by single-crystal X-ray diffraction (XRD), powder XRD, IR spectroscopy, elemental analysis, and thermogravimetric analysis (TGA). In compounds 1−3 and 6, each [ZnO 4 ] tetrahedron shares three corners with three neighboring [PCO 3 ] tetrahedra to generate a Zn−O−P layer, which consists of eight and four member rings (MRs). While in compounds 4 and 5, each [MnO 6 ] octahedron shares four corners with neighboring four [PCO 3 ] tetrahedra into a Mn−O−P layer containing eight MRs. The organic groups hang on two sides of a Zn−O−P or Mn−O−P layer to form two-dimensional (2D) sandwich-like frameworks of compounds 1−6. TGA and powder XRD reveal that 2D frameworks of compounds 2, 3, 4, and 6 are thermally stable up to 180, 250, 230, and 250°C under an air atmosphere, respectively. It is interesting that compounds 1−2 display bright UV luminescence, which can be irreversibly quenched by UV irradiation. In addition, the blue luminescence of solid 6 can be transformed into blue-green emission by simply a heating treatment. ■ INTRODUCTIONThe study of metal phosphonates is an ongoing field of research, due to their structural diversities and potential applications as porous materials, ion-exchangers, proton conductors, Langmuir−Blodgett Films, nonlinear optics, molecular sensors, catalysts, magnets, and so on. 1−3 The phosphonate group has three oxygen atoms that can take part in coordination with metal ions, resulting in the low solubility of metal phosphonates in nature. During the last four years, much effort has been devoted to modify phosphonic acids with additional groups, including amino, carboxylate, thienyl, pyridyl, hydroxyl, triazole, imidazole, piperidine, pyrazine, and thiophene. 4−13 As a result, many intriguing metal phosphonates have been obtained and structurally characterized, such as calcium phosphonates with tuned proton conductivity. 4a In this regard, we have recently focused on our attention on the synthesis of functionalized phosphonic acids by the combination of the N(CH 2 COOH)(CH 2 PO 3 H 2 ) moiety and other organic groups. On the basis of these functionalized phosphonate ligands, 12 luminescent metal phosphonates with three-dimensional (3D) frameworks, hybrid layers, or polynuclear clusters, have been obtained under hydrothermal conditions. 14 In order to explore new luminescent metal phosphonates based on 1-C 10 H 7 -CH 2 N(CH 2 COOH)-(CH 2 PO 3 H 2 ) (H 3 L1; Scheme 1), many experiments have been continuously performed under different reaction conditions. On the other hand, 4-HOOCC 6 H 4 CH 2 NCH 2 PO 3 H 2 ) 2 has been proven to be an useful ligand for the formation of metal phosphonates with different frameworks. 15 For instance, layered [Cd 3 (H 2 O) 3 (4-HOOCC 6 H 4 CH 2 NH(CH 2 PO 3 ) 2 )]· 11H 2 O can be reversibly dehydrated−hydrated, and intercalated addition...

Section: Introductionmentioning

confidence: 99%

New Layered Metal Phosphonates Based on Functionalized Phosphonic Acids

2015

“…It is interesting that neither free nor coordinated water molecules are in compound 1 . This is obviously different from the reported lanthanide phosphonates. ,, Comparing the structure of compound 1 with those of divalent metal 3-ammonium-1-hydroxypropylidene-1,1-diphosphonates, the protonation of the L 4– anion plays an important role on dimensionalities of the framework. Since all hydrogen atoms of phosphonate groups are deprotonated, compound 1 and [Cu 3 (HL) 2 (H 2 O) 2 ] exhibit a 3D framework.…”

Section: Resultsmentioning

confidence: 64%

“…Thus, it is still difficult to grow single crystals with suitable size and high quality for X-ray structural analysis. However, this obstacle has been conquered to a certain extent, by modifying phosphonic acid with additional groups such as amino, carboxylate, thienyl, pyridyl, hydroxyl, triazole, imidazole, piperidine, pyrazine, thiophene, and sulfonate. − This is due to that additional groups can enrich coordination modes to improve the solubility and crystallinity of metal phosphonates. As a result, many intriguing metal phosphonates have been designed and synthesized during the past 5 years, such as cobalt-lanthanide phosphonates possessing a potential capability for magnetic cooling at low temperature and high magnetocaloric effects, , a heterometallic phosphonate with interesting relaxometric properties, as well as a copper phosphonate displaying a strong breathing effect .…”

Section: Introductionmentioning

confidence: 99%

“…As a result, many intriguing metal phosphonates have been designed and synthesized during the past 5 years, such as cobalt-lanthanide phosphonates possessing a potential capability for magnetic cooling at low temperature and high magnetocaloric effects, , a heterometallic phosphonate with interesting relaxometric properties, as well as a copper phosphonate displaying a strong breathing effect . However, only several lanthanide phosphonates have been reported because they are rarely crystalline for they are highly insoluble. ,,,, In this regard, many efforts have been devoted to obtain suitable single crystals of lanthanide phosphonates to determine their accurate structures by single-crystal X-ray diffraction and investigate their properties. Herein, we have selected 3-ammonium-1-hydroxypropylidene-1,1-diphosphonic acid ( + H 3 NCH 2 CH 2 C(OH)(PO 3 H 2 )(PO 3 H – ), H 4 L) with three functional groups (OH, NH 2 , and PO 3 H 2 ) to construct new lanthanide phosphonates in view of the following aspects.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

New 3D Lanthanide Phosphonates: Syntheses, Crystal Structure, Thermal Stability, Luminescence, and Magnetism

2014

Hydrothermal reactions of lanthanide oxide or lanthanide chloride with 3-ammonium-1-hydroxypropylidene-1,1-diphosphonic acid (+H3NCH2CH2C(OH)(PO3H2)(PO3H–), H4L) afforded seven new lanthanide phosphonates, namely, [Ln(HL)] (Ln = Eu (1), Tb (2), Sm (3), Gd (4), Er (5), Nd (6), and Pr (7)). Compounds 1–7 are characterized by single-crystal X-ray diffraction, powder XRD, elemental analysis, IR spectroscopy, and thermogravimetric analysis (TGA). Compounds 1–5 crystallize in the orthorhombic Pnma space group, whereas compounds 6 and 7 crystallize in the monoclinic P2(1)/c space group. Compounds 1–7 exhibit a similar 3D open framework with eight-membered ring channels, which are occupied by organic pendants of CH2CH2NH3. TGA and PXRD reveal that compound 1 is thermally stable up to 350 °C under an air atmosphere. It is interesting that compounds 1 and 2 display bright red and green luminescence, respectively, which can be further enhanced obviously upon cooling to 10 K. It is worth noting that the bright red emission of compound 1 can be preserved after heat-treatment at 350 °C under an air atmosphere. Compounds 6 and 7 can give off NIR luminescence and near UV emission, respectively. Furthermore, the magnetic properties of solids 1 and 3–6 have also been studied.

“…Metal phosphonates are of great research interest because of their structural and compositional diversity, as well as their thermal and chemical stability for potential applications as porous materials, ion exchangers, proton conductors, Langmuir–Blodgett films, nonlinear optics, molecular sensors, catalysts, magnets, etc. − Because of the low solubility and crystallinity of metal phosphonates, it is still difficult to grow single crystals of a suitable size and high quality for X-ray structural analysis. In recent years, much effort has been devoted to modifying phosphonic acids with additional groups, including amino, carboxylate, pyridyl, triazole, thienyl, and imidazole groups. − This is due to the fact that additional groups can enrich coordination modes to improve the solubility and crystallinity of metal phosphonates. As a result, a variety of intriguing metal phosphonates have been obtained and structurally characterized, such as calcium phosphonates with tuned proton conductivity .…”

Section: Introductionmentioning

confidence: 99%

Two New Zinc Phosphonates with Triazine-Based Phosphonic Acids

2015

Hydrothermal reactions of Zn(CH 3 COO) 2 •2H 2 O with two new triazine-based phosphonic acids, 2,4,6-triglyphosate-1,3,5-triazine (H 9 L1) and 4,6biglyphosate-2-hydroxyl-1,3,5-triazine (H 6 L2), afforded two new zinc phosphonates, namely, [(C 5 H 14 N 2 )Zn 3 (HL1)(H 2 O)]•3.5H 2 O (1) and [(C 5 H 14 N 2 )-Zn 2 L2]•3H 2 O ( 2), respectively. The two zinc phosphonates were structurally characterized through single-crystal X-ray diffraction. Compound 1 is a threedimensional (3D) framework in that Zn−O−P chains are connected by HL1 8− anions with hendecadentate modes. In compound 2, each L2 6− anion links four Zn2 binuclear units to form a 3D framework. In both compounds 1 and 2, the protonated 2-methylpiperazines are encapsulated into the channels of 3D frameworks. Thermogravimetric analysis and powder X-ray diffraction reveal that compounds 1 and 2 are thermally stable up to 200 and 160 °C under an air atmosphere, respectively. Compounds 1 and 2 display near-UV and purple luminescence with maximal bands at 377 and 402 nm, respectively. It worth noting that the luminescence of solids 1 and 2 can be preserved after compounds 1 and 2 are heated at 200 and 160 °C for 2 h under an air atmosphere, respectively. In addition, the ion-exchange property of compound 1 was also studied.