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Exploring metal phosphonates with new crystal structures is of significance for the development of metal-organic frameworks (MOFs). In this work, two new copper phosphonates, [tetraauqa-1,4-phenylenebis(hydroxymethylene))bisphosphonate biscopper(II)] bishydrate [Cu2(H2L)(H2O)4]·2H2O (1) and 1,4-phenylenebis(hydroxymethylene))bisphosphonate-(4,4'-bipy) copper(II) [Cu(H4L)(4,4'-bipy)] (2) (4,4'-bipy = 4,4'-bipyridine), have been synthesized from a hydroxy functionalized bisphosphonate ligand, H6L = (1,4-phenylenebis(hydroxymethylene))bis(phosphonic acid). The introduction of a hydroxy group can regulate the crystal structures. The bisphosphonate ligand in 1 is hexadentate, binding six copper ions with its six phosphonate oxygen atoms and two hydroxy oxygen atoms, forming a three-dimensional framework structure with rectangle channels running along the b-direction. For 2, the bisphosphonate ligands are double deprotonated and chelate or bridge two copper ions, showing a two-dimensional layered crystal structure. These compounds have interesting fluorescence properties with emission maxima (307 and 410 nm) lying in the blue region. [ABSTRACT FROM AUTHOR]

Two new uranyl diphosphonates, namely, [UO 2 (H 3 L 1 ) 2 (H 2 O)]·4H 2 O ( 1 ) and [UO 2 (H 3 L 2 )(H 2 O)]·3H 2 O ( 2 ), H 4 L 1  = PyNHCH(PO 3 H 2 ) 2 , H 5 L 2  = Py(COOH)NHCH(PO 3 H 2 ) 2 , have been hydrothermally synthesized from the reactions of two diphosphonate ligands with uranyl nitrate hexahydrate and characterized systematically using powder and single-crystal X-ray diffraction, IR, EA, TGA and fluorescent emission measurements. The proton transfer from the phosphonic acid groups to the pyridine and imine groups leads to the formation of zwitterionic ligands. The diphosphonate ligand in compound 1 adopts chelate coordination mode resulting in molecular structure while displays chelate-bridging coordination mode in compound 2 leading to the formation of 1D infinite chain structure. The fluorescent properties of compounds 1 and 2 were also investigated. [ABSTRACT FROM AUTHOR]

A new uranyl triphosphonate with three-dimensional crystal structure has been synthesized from a semi-rigid triphosphonate ligand using hydrothermal method. The employment of triphosphonate ligand may provide a new strategy for the construction of higher dimensional uranyl phosphonates. The thermal and luminescent properties were also investigated. [ABSTRACT FROM AUTHOR]

By employing an aromatic methyl substituted V-shaped diphosphonic acid as a ligand, a series of metal diphosphonates, namely [Cu3(HL)2(H2O)2][(H2O)2] (1), [Cu(H2L)(pyz)(H2O)2][(H2O)2] (2), [Cu(H2L)(2,2′-bipy)] (3), [Cu(H2L)(4,4′-bipy)(H2O)2] (4), [Zn(H2L)(2,2′-bipy)] (5) and [Cd(H2L)(2,2′-bipy)(H2O)][(H2O)6] (6), have been synthesized. The structural studies reveal that these compounds exhibit diverse crystal structures. The introduction of the methyl group and pyridine derived auxiliary ligands results in the formation of plenty of C–H…O, C–H…π and π…π interactions, which contribute to the crystallization of metal diphosphonates. It was found that the Zn and Cd containing compounds showed intense intraligand emissions. [ABSTRACT FROM AUTHOR]

One series of isostructural lanthanide phosphonates, namely [Ln2(H2L)3][(H2O)5] (H4L = (5-methyl-1,3-phenylene)bis(phosphonic acid); Ln = Eu (1), Gd (2), Tb (3), and Dy (4)), have been successfully synthesized from a V-shaped rigid ligand. Systematic characterizations using single-crystal and powder X-ray diffraction (XRD), thermogravimetric analyses (TGA), and photoluminescence spectroscopy were accomplished. It was found that these compounds all crystallize in the cubic I213 space group, showing three-dimensional framework structures. The frameworks are stable up to 350 °C and show their respective characteristic metal-centered emissions. The photoluminescence properties were also theoretically investigated by using a newly developed software program – LUMPAC. The energy transfer and back energy transfer rates were estimated, and the T1→5D1 and T1→5D0 channels were revealed to be the dominant pathways. The combination of experimental and theoretical studies on the photoluminescence properties substantially supports the understanding and design of highly luminescent inorganic–organic hybrid materials. [ABSTRACT FROM AUTHOR]

Abstract: Two lead (II) trisphosphonates, [Pb3(H3L1)2(H2O)] (1) and [Pb5(HL2)(H3L2)(H4L2)(H2O)2][(H2O)2] (2), have been synthesized from two trisphosphonate ligands and characterized by EA, IR, UV–vis, TGA, powder and single-crystal X-ray diffraction methods. The single-crystal X-ray diffraction analyses reveal that they both feature three-dimensional framework structures. The lead (II) ions are mainly five-coordinated, forming square pyramid coordination geometry. Although the two trisphosphonate ligands are very similar, different coordination modes and conformations are observed for them, suggesting that attachment of methyl groups to the central benzene ring has a major effect on the structure formation. They both absorb below 325nm and are thermally robust. [Copyright &y& Elsevier]

Four rare earth carboxylates, namely [Y(L) (DMF) (H 2 O)]·H 2 O (1), Y(L) (H 2 O) (2), La(L) (DMF) (3) and La(L) (H 2 O) (4), have been hydro/solvothermally synthesized from 2-(6-carboxypyridin-2-yl)terephthalic acid (H 3 L) and systematically characterized using IR, EA, single-crystal and powder X-ray diffraction, luminescence methods. The structural characterizations reveal that the crystal structures of rare earth carboxylates can be effectively altered by judicious alteration of the synthesis conditions. These complexes are very stable and display intense intraligand emissions. Four rare earth carboxylates with interesting crystal structures have been synthesized from a rigid polydentate carboxylate ligand containing pyridine group and systematically characterized. Image 1 [ABSTRACT FROM AUTHOR]