Tailor-Made Zinc Uranyl Diphosphonates from Layered to Framework Structures

Hydrothermal reactions of zinc uranyl acetate and 1-hydroxyethylidenediphosphonic acid (H₄L) with 1,10-phenanthroline (phen), 2,2′-bipyridine (bipy), 1<i>H</i>-benzo­[<i>d</i>]­imidazole (bi), or 1-phenyl-1<i>H</i>-imidazole (pi) resulted in the formation of four new zinc uranyl compounds, namely, [Zn₂(phen)₂(UO₂)₂(L)₂(H₂O)₃]·3H₂O (<b>ZnUP-1</b>), Zn₂(bipy)₂(UO₂)₂(L)₂(H₂O)₂ (<b>ZnUP-2</b>), (Hbi)­[Zn_0.5(UO₂)₂(L)­(H₂L)­(H₂O)₃]·3H₂O (<b>ZnUP-3</b>), and (Hpi)­[Zn­(UO₂)₂(H₂O)₄(L)­(HL)]·H₂O (<b>ZnUP-4</b>). These four structures all comprise uranyl diphosphonate layers formed by UO₇ pentagonal bipyramids and PO₃C tetrahedra. Such layers are further connected by Zn-centered polyhedra by sharing oxygens from phosphonate groups. For <b>ZnUP-1</b> and <b>ZnUP-2</b>, the zinc atoms are terminally coordinated by phen and bipy molecules, respectively, resulting in two-dimensional (2-D) hybrid materials. In <b>ZnUP-3</b> and <b>ZnUP-4</b>, the uranyl phosphonate layers are joined together by Zn–O polyhedra forming three-dimensional (3-D) frameworks. The structures of <b>ZnUP-3</b> and <b>ZnUP-4</b> contain large channels along the <i>a</i>-axis with apertures around 3.4 × 13.3 and 4.4 × 12.2 Ų, respectively. Protonated templates exist in the channels, filling the space and compensating the negative charge of the anionic frameworks. Photoluminescent studies reveal that <b>ZnUP-1</b> and <b>ZnUP-2</b> exhibit the characteristic vibronically coupled charge-transfer based UO₂²⁺ emission

Tailor-Made Zinc Uranyl Diphosphonates from Layered to Framework Structures

Hydrothermal reactions of zinc uranyl acetate and 1-hydroxyethylidenediphosphonic acid (H₄L) with 1,10-phenanthroline (phen), 2,2′-bipyridine (bipy), 1<i>H</i>-benzo­[<i>d</i>]­imidazole (bi), or 1-phenyl-1<i>H</i>-imidazole (pi) resulted in the formation of four new zinc uranyl compounds, namely, [Zn₂(phen)₂(UO₂)₂(L)₂(H₂O)₃]·3H₂O (<b>ZnUP-1</b>), Zn₂(bipy)₂(UO₂)₂(L)₂(H₂O)₂ (<b>ZnUP-2</b>), (Hbi)­[Zn_0.5(UO₂)₂(L)­(H₂L)­(H₂O)₃]·3H₂O (<b>ZnUP-3</b>), and (Hpi)­[Zn­(UO₂)₂(H₂O)₄(L)­(HL)]·H₂O (<b>ZnUP-4</b>). These four structures all comprise uranyl diphosphonate layers formed by UO₇ pentagonal bipyramids and PO₃C tetrahedra. Such layers are further connected by Zn-centered polyhedra by sharing oxygens from phosphonate groups. For <b>ZnUP-1</b> and <b>ZnUP-2</b>, the zinc atoms are terminally coordinated by phen and bipy molecules, respectively, resulting in two-dimensional (2-D) hybrid materials. In <b>ZnUP-3</b> and <b>ZnUP-4</b>, the uranyl phosphonate layers are joined together by Zn–O polyhedra forming three-dimensional (3-D) frameworks. The structures of <b>ZnUP-3</b> and <b>ZnUP-4</b> contain large channels along the <i>a</i>-axis with apertures around 3.4 × 13.3 and 4.4 × 12.2 Ų, respectively. Protonated templates exist in the channels, filling the space and compensating the negative charge of the anionic frameworks. Photoluminescent studies reveal that <b>ZnUP-1</b> and <b>ZnUP-2</b> exhibit the characteristic vibronically coupled charge-transfer based UO₂²⁺ emission

The First Uranyl Arsonates Featuring Heterometallic Cation–Cation Interactions with U^VIO–Zn^II Bonding

Two new uranyl arsonates, Zn­(UO₂)­(PhAsO₃)₂L·H₂O [L = 1,10-phenanthroline (<b>1</b>) and 2,2′-bipyridine (<b>2</b>)], have been synthesized by hydrothermal reactions of phenylarsonic acid, L, and ZnUO₂(OAc)₄·7H₂O. Single-crystal X-ray analyses demonstrate that these two compounds are isostructural and exhibit one-dimensional chains in which U^VI and Zn^II cations are directly connected by the <i>yl</i> oxygen atoms and additionally bridged by arsonate groups. Both compounds represent the first examples of uranyl arsonates with heterometallic cation–cation interactions

Construction of Three-Dimensional Cobalt(II)-Based Metal–Organic Frameworks by Synergy between Rigid and Semirigid Ligands

Solvothermal assembly of Co­(II) ion, a semirigid tetrahedral carboxylate ligand tetrakis­[(4-carboxyphenyl)­oxamethyl]­methane acid (H₄L), and rigid linear bidentate linker 1,4-di­(1<i>H</i>-imidazol-1-yl)­benzene (dib) or 4,4′-di­(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl (dibp) yields four novel metal–organic frameworks (<b>1</b>–<b>4</b>) with different topological connections. [Co₂(L)­(dib)]·3DMF (<b>1</b>) is a 2-fold interpenetrating <i>sqc</i>422 network and contains 3-dimensional interconnected channels along [100], [010], and [110] directions; [Co₄(L)₂(dib)₃(H₂O)₄]·4H₂O (<b>2</b>) is a three-dimensional 3,4,4-connected new topology with 5-fold interpenetration; [Co₂(L)­(dibp)]·5DMF (<b>3</b>) and Co₂(L)­(dibp)₂ (<b>4</b>) are formed in the presence of dibp linker; they feature three-dimensional novel topologies based on 4,6-connection and 4,4-connection, respectively, and no interpenetration is observed. It is demonstrated that interpenetration is accessible simply by changing auxiliary ligands and solvents. Magnetic studies reveal that complexes <b>1</b> and <b>3</b> exhibit antiferromagnetic behavior

Construction of Three-Dimensional Cobalt(II)-Based Metal–Organic Frameworks by Synergy between Rigid and Semirigid Ligands

Solvothermal assembly of Co­(II) ion, a semirigid tetrahedral carboxylate ligand tetrakis­[(4-carboxyphenyl)­oxamethyl]­methane acid (H₄L), and rigid linear bidentate linker 1,4-di­(1<i>H</i>-imidazol-1-yl)­benzene (dib) or 4,4′-di­(1<i>H</i>-imidazol-1-yl)-1,1′-biphenyl (dibp) yields four novel metal–organic frameworks (<b>1</b>–<b>4</b>) with different topological connections. [Co₂(L)­(dib)]·3DMF (<b>1</b>) is a 2-fold interpenetrating <i>sqc</i>422 network and contains 3-dimensional interconnected channels along [100], [010], and [110] directions; [Co₄(L)₂(dib)₃(H₂O)₄]·4H₂O (<b>2</b>) is a three-dimensional 3,4,4-connected new topology with 5-fold interpenetration; [Co₂(L)­(dibp)]·5DMF (<b>3</b>) and Co₂(L)­(dibp)₂ (<b>4</b>) are formed in the presence of dibp linker; they feature three-dimensional novel topologies based on 4,6-connection and 4,4-connection, respectively, and no interpenetration is observed. It is demonstrated that interpenetration is accessible simply by changing auxiliary ligands and solvents. Magnetic studies reveal that complexes <b>1</b> and <b>3</b> exhibit antiferromagnetic behavior

The First Uranyl Arsonates Featuring Heterometallic Cation–Cation Interactions with U^VIO–Zn^II Bonding

Two new uranyl arsonates, Zn­(UO₂)­(PhAsO₃)₂L·H₂O [L = 1,10-phenanthroline (<b>1</b>) and 2,2′-bipyridine (<b>2</b>)], have been synthesized by hydrothermal reactions of phenylarsonic acid, L, and ZnUO₂(OAc)₄·7H₂O. Single-crystal X-ray analyses demonstrate that these two compounds are isostructural and exhibit one-dimensional chains in which U^VI and Zn^II cations are directly connected by the <i>yl</i> oxygen atoms and additionally bridged by arsonate groups. Both compounds represent the first examples of uranyl arsonates with heterometallic cation–cation interactions

Flexible Diphosphonic Acids for the Isolation of Uranyl Hybrids with Heterometallic U^VIOZn^II Cation–Cation Interactions

A family of uranyl diphosphonates have been hydrothermally synthesized using various flexible diphosphonic acids and Zn­(UO₂)­(OAc)₄·7H₂O in the presence of bipy or phen. Single-crystal X-ray analyses indicate that these compounds represent the first examples of uranyl phosphonates with heterometallic U^VIOZn^II cation–cation interactions

Flexible Diphosphonic Acids for the Isolation of Uranyl Hybrids with Heterometallic U^VIOZn^II Cation–Cation Interactions

A family of uranyl diphosphonates have been hydrothermally synthesized using various flexible diphosphonic acids and Zn­(UO₂)­(OAc)₄·7H₂O in the presence of bipy or phen. Single-crystal X-ray analyses indicate that these compounds represent the first examples of uranyl phosphonates with heterometallic U^VIOZn^II cation–cation interactions

Structural Variations of the First Family of Heterometallic Uranyl Carboxyphosphinate Assemblies by Synergy between Carboxyphosphinate and Imidazole Ligands

Hydrothermal reactions of uranyl acetate and a series of transition metal acetates with a carboxyphosphinate and auxiliary N-donor ligands gave rise to the formation of eight heterometallic uranyl-organic assemblies, namely, Co­(im)₂(UO₂)₃(L)₄ (<b>1</b>), Zn­(bpi)­(UO₂)­(L)₂ (<b>2</b>), Cd­(dib)­(UO₂)­(L)₂ (<b>3</b>), M­(dib)­(UO₂)₂(L)₃ (M = Cd (<b>4</b>), Mn (<b>5</b>)), and [M­(dib)₂(H₂O)₂]­[(UO₂)₃(L)₄]·nH₂O (M = Co (<b>6</b>, n = 2), Ni (<b>7</b>, n = 2), Cu (<b>8</b>, n = 0)) [H₂L = (2-carboxyethyl)­(phenyl)­phosphinic acid (CPP), im = imidazole, bpi =1-(biphenyl-4-yl)-1H-imidazole, dib =1,4-di­(1H-imidazol-1-yl)­benzene]. Single-crystal X-ray diffraction (XRD) analysis of <b>1</b> reveals a layered structure of UO₆, UO₇, and CoO₄N₂ units that are linked by the carboxyphosphinate ligands. Imidazole molecules modify the layer by coordinating to Co centers. Similarly, <b>2</b> is a mixed zinc-uranyl carboxyphosphinate with different topological two-dimensional structure and the decorated moiety is a bpi coligand. When in the presence of bridging dib coligands, the mixed cadmium–uranyl carboxyphosphinate sheets of <b>3</b> are pillared by dib forming a framework structure. The isostructures of <b>4</b> and <b>5</b> are also pillared frameworks constructed by a mixed heterometallic uranyl phosphinate layered subnet that is different from that of <b>3</b>. The structures of <b>6</b>–<b>8</b> are isotype and very special in that they consist of distinct [M­(dib)₂(H₂O)₂]_n²ⁿ⁺ cationic and [(UO₂)₃(L)₄]_n^2n– anionic subnets. Such two sheets are packed alternatively and interact via hydrogen bond forming three-dimensional supramolecular structures

Structural Variation within Heterometallic Uranyl Hybrids Based on Flexible Alkyldiphosphonate Ligands

Five novel zinc uranyl diphosphonates have been hydrothermally synthesized by using a series of flexible diphosphonate ligands, including ethane-1,2-diyldiphosphonic acid (H₄EDP), propane-1,3-diyldiphosphonic acid (H₄PDP), and butane-1,4-diyldiphosphonic acid (H₄BDP). Compound Zn­(H₂tib)­(UO₂)₂(EDP)­(HEDP)­(H₂EDP)_0.5·3H₂O (<b>EDP-ZnU1</b>, tib = 1,3,5-tri­(1H-imidazol-1-yl)­benzene) comprises dimeric U₂O₁₂ unit condensed by two UO₇ pentagonal bipyramids, which are further connected by Zn-centered polyhedra and EDP ligands resulting in a 3-dimensional framework. Compound [Zn­(bipy)­(H₂O)]­(UO₂)­(PDP) (<b>PDP-ZnU1</b>, bipy = 2,2′-bipyridine) also features U₂O₁₂ dimers and Zn-centered polyhedra, but a layered arrangement is formed. Different from that in <b>PDP-ZnU1</b>, the uranium exists in the form of UO₆ tetragonal bipyramid and is surrounded by four PDP ligands to generate the layered structure of Zn­(bipy)­(UO₂)­(PDP) (<b>PDP-ZnU2</b>). ZnO₂N₂ tetrahedra are connected on both sides of the layers. Both Zn₂(phen)₄(UO₂)₃(BDP)­(HBDP)₂·4H₂O (<b>BDP-ZnU1</b>, phen = 1,10-phenanthroline) and Zn₂(bipy)₂(UO₂)₃(HBDP)₂(H₂BDP)₂ (<b>BDP-ZnU2</b>) contain U₂O₁₂ dimers and UO₆ tetragonal bipyramids. In <b>BDP-ZnU1</b>, uranyl centers are bridged by BDP to form a 2-dimensional structure, on which Zn­(phen)₂ are decorated. Whereas in <b>BDP-ZnU2</b>, uranyl phosphonate layers are connected by bridging ZnO₃N₂ to produce framework structure. All of these compounds have been investigated by IR and photoluminescent spectroscopy. Their characteristic green light emissions have been attributed to transition properties of uranyl dications