Solvent-Controlled Syntheses, Structure, and Magnetic Properties of Trinuclear Mn(II)-Based Metal–Organic Frameworks

Solvothermal reactions of manganese­(II) salts with hexa­[4-(carboxyphenyl)­oxamethyl]-3-oxapentane acid (H₆L) afforded a family of porous metal–organic frameworks, namely, Mn₃(L)­(DMA)₄·2DMA (<b>1</b>, <i>C</i>2/<i>c</i>), Mn₃(L)­(H₂O)₂(DMF)₂·8DMF (<b>2</b>, <i>Cc</i>), and Mn₃(L)­(H₂O)₂(DMF)·4DMF (<b>3</b>, <i>P</i>2₁/<i>c</i>). All compounds have been characterized by elemental analysis and thermogravimetric analysis and structurally confirmed by single-crystal X-ray diffractions. Their structures consist of three types of trinuclear Mn^II subunits, which are further bridged by the carboxylic ligand, resulting in two types of topological nets (pts and sra). All of the Mn^II₃ subunits are terminally coordinated by solvent molecules. The structure of the Mn^II₃ core in <b>1</b> is symmetric with an inversion center, whereas those in <b>2</b> and <b>3</b> display a symmetry-breaking phenomenon. Their magnetic behaviors exhibit interesting variations, in which the local net magnetization at low temperature increases gradually from <b>1</b> to <b>3</b>. Such magnetic evolution behavior in trinuclear subunits has never been observed previously

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

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

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