Li-Hua Huo

A series of three-dimensional lanthanide metal–organic frameworks with biphenylethene-4,4′-dicarboxylic acid: Hydrothermal syntheses and structures

Biphenylethene-4,4′-dicarboxylic acid (H2bpea) reacts with lanthanide(III) oxide (Ln = Sm, Eu, Gd, Tb, Er) or nitrate salts of lanthanide(III) (Ln = Eu, La, Tb) under hydrothermal conditions to form a series of lanthanide complexes 1–8, which were characterized by elemental analysis, IR, PL TG and single-crystal X-ray diffraction. These eight complexes exhibit four different kinds of 3-D frameworks. The complexes [Ln(bpea)(formate)]n (Ln = Sm (1), Eu (2), Gd (3), Tb (4), Er (5)) were isomorphous and exhibited 3-D pillared layered frameworks. The eight-coordinated lanthanide ions in complexes 1–5 are bridged by the formate anions into 2-D covalent nets, which are further interconnected by the bpea ligands to produce the 3-D framework. While the formate anions are neglected, the new generated 3-D framework shows a four-connected SrAl2 net. The nine-coordinated europium ions in complex [Eu(bpea)(formate)]n (6) are also bridged by the formate anions into similar 2-D covalent nets, which are further interconnected by the bpea ligands to produce a different 3-D framework. Interestingly, complex 6 displays a 2-fold interpenetrating 3-D structure with Pts topology while neglecting the formate anions. The main reason is due primarily to the coordination geometry of the europium ion and the novel μ4:η6-bridging coordination mode of the bpea ligands. Complexes 7 and 8 have the same composition of [Ln(bpea)1.5(H2O)2]n (Ln = La (7) and Tb (8)), but crystallize in the P21/n and P space groups, respectively. In complex 7, the lanthanum centers are bridged by the bpea ligands in a common μ4:η4-bridging coordination mode into 2-D double layer motifs, which are further connected by the other μ4:η4-bridging bpea ligands to produce a 3-D hybrid framework with sixty-membered macro rings. By contrast, the terbium centers in complex 8 are bridged by the bpea ligands in an unprecedented μ4:η5-bridging coordination mode into 2-D layer architectures, which are further connected by the other μ2:η2-bridging bpea ligands to produce a 3-D hybrid framework.

New family of silver(I) complexes based on hydroxyl and carboxyl groups decorated arenesulfonic acid: syntheses, structures, and luminescent properties.

Self-assembly of silver(I) salts and three ortho-hydroxyl and carboxyl groups decorated arenesulfonic acids affords the formation of nine silver(I)-sulfonates, (NH(4))·[Ag(HL1)(NH(3))(H(2)O)] (1), {(NH(4))·[Ag(3)(HL1)(2)(NH(3))(H(2)O)]}(n) (2), [Ag(2)(HL1)(H(2)O)(2)](n) (3), [Ag(2)(HL2)(NH(3))(2)]·H(2)O (4), [Ag(H(2)L2)(H(2)O)](n) (5), [Ag(2)(HL2)](n) (6), [Ag(3)(L3)(NH(3))(3)](n) (7), [Ag(2)(HL3)](n) (8), and [Ag(6)(L3)(2)(H(2)O)(3)](n) (9) (H(3)L1 = 2-hydroxyl-3-carboxyl-5-bromobenzenesulfonic acid, H(3)L2 = 2-hydroxyl-4-carboxylbenzenesulfonic acid, H(3)L3 = 2-hydroxyl-5-carboxylbenzenesulfonic acid), which are characterized by elemental analysis, IR, TGA, PL, and single-crystal X-ray diffraction. Complex 1 is 3-D supramolecular network extended by [Ag(HL1)(NH(3))(H(2)O)](-) anions and NH(4)(+) cations. Complex 2 exhibits 3-D host-guest framework which encapsulates ammonium cations as guests. Complex 3 presents 2-D layer structure constructed from 1-D tape of sulfonate-bridged Ag1 dimers linked by [(Ag2)(2)(COO)(2)] binuclear units. Complex 4 exhibits 3-D hydrogen-bonding host-guest network which encapsulates water molecules as guests. Complex 5 shows 3-D hybrid framework constructed from organic linker bridged 1-D Ag-O-S chains while complex 6 is 3-D pillared layered framework with the inorganic substructure constructing from the Ag2 polyhedral chains interlinked by Ag1 dimers and sulfonate tetrahedra. The hybrid 3-D framework of complex 7 is formed by L3(-) trianions bridging short trisilver(I) sticks and silver(I) chains. Complex 8 also presents 3-D pillared layered framework, and the inorganic layer substructure is formed by the sulfonate tetrahedrons bridging [(Ag1O(4))(2)(Ag2O(5))(2)](∞) motifs. Complex 9 represents the first silver-based metal-polyhedral framework containing four kinds of coordination spheres with low coordination numbers. The structural diversities and evolutions can be attributed to the synthetic methods, different ligands and coordination modes of the three functional groups, that is, sulfonate, hydroxyl and carboxyl groups. The luminescent properties of the nine complexes have also been investigated at room temperature, especially, complex 1 presents excellent blue luminescence and can sensitize Tb(III) ion to exhibit characteristic green emission.

Well-Designed Strategy To Construct Helical Silver(I) Coordination Polymers from Flexible Unsymmetrical Bis(pyridyl) Ligands: Syntheses, Structures, and Properties

In this Article, self-assembly of AgX (X = NO3(-) and ClO4(-)) salts and four flexible unsymmetrical bis(pyridyl) ligands, namely, N-(pyridin-2-ylmethyl)pyridin-3-amine (L1), N-(pyridin-3-ylmethyl)pyridin-2-amine (L2), N-(pyridin-4-ylmethyl)pyridin-2-amine (L3), and N-(pyridin-4-ylmethyl)pyridin-3-amine (L4), results in the formation of eight helical silver(I) coordination polymers, [Ag(L)(NO3)]n [L = L1 (1), L2 (2), L3 (3), L4 (4)] and [Ag(L)(ClO4)]n [L = L1 (5), L2 (6), L3 (7), L4 (8)], which have been characterized by elemental analysis, IR, TG, PL, and powder and single-crystal X-ray diffraction. The alternating one-dimensional (1-D) left- and right-handed helical chains are included in achiral complexes 1-3 and 5-8. By contrast, the ligand L4 only alternately bridges Ag(I) cation to form the 1-D right-handed helical chain in complex 4. The pitches of these helical chains locate in the range 5.694(5)-17.016(6) Å. Meanwhile, the present four unsymmetrical bis(pyridyl) ligands in the eight complexes present diverse cis-trans and trans-trans conformation and facilitate the construction of helical structures. Moreover, the solid-state luminescent emission intensities of the perchlorate-containing complexes are stronger than those of nitrate-containing complexes at room temperature.

Inorganic anion induced supramolecular architectures and luminescent properties of flexible bis(pyridyl) based ionic salts

Self-assembly of four bis(pyridyl) organic molecules with long flexible spacer, 1,4-bis(2-pyridylaminomethyl)benzene (M1), 1,4-bis(3-pyridylaminomethyl)benzene (M2), 1,3-bis(2-pyridylaminomethyl)benzene (M3) and 1,3-bis(3-pyridylaminomethyl)benzene (M4), and different inorganic acids (HNO3 and HClO4) leads to the formation of eight salts, H2M122++·2NO3− (1), H2M222++·2NO3− (2), H2M322++·2NO3− (3), H2M422++·2NO3− (4), H2M122++·2ClO4− (5), H2M222++·2ClO4− (6), H2M322++·2ClO4− (7), and H2M422++·2ClO4− (8), which have been characterized by elemental analysis, IR, TG, PL and single-crystal X-ray diffraction. Salts 1, 3 and 7 exhibit 2-D supramolecular structures extended by hydrogen bonds, C–H⋯π and anion⋯π, while salts 2, 4, 5, 6 and 8 exhibit 3-D supramolecular networks extended by hydrogen bonds, π⋯π stacking, C–H⋯π and anion⋯π. The diverse supramolecular networks depend on the various conformation modes (trans-trans-trans, trans-trans-cis and cis-trans-trans) of the four flexible bis(pyridyl) cations, various weak non-covalent interactions as well as the configuration of anions. These supramolecular aggregations 1–8 exhibit intense emissions in the solid-state at room temperature, and the emission intensities of the perchlorates are far stronger than those of nitrates.

Structure modulations in luminescent alkaline earth metal-sulfonate complexes constructed from dihydroxyl-1,5-benzenedisulfonic acid: Influences of metal cations, coordination modes and pH value

Seven novel alkaline earth (AE) metal-sulfonate complexes constructed from ortho-hydroxyl arenedisulfonic acids, [Mg2(H2L)2(H2O)4]·8H2O (1), {[Ca(H2L)(H2O)]n·3nH2O} (2), {[Ca4L2(H2O)12]n·7nH2O} (3), {[Sr(H2L)(H2O)]n·3nH2O} (4), {[Sr2L(H2O)4]n·nH2O} (5), {[Ba(H2L)(H2O)2]n·2nH2O} (6), and [Ba2L(H2O)4]n (7) (H4L = 2,4-dihydroxyl-1,5-benzenedisulfonic acid), have been synthesized and characterized by elemental analysis, IR, TG, PL, powder and single-crystal X-ray diffraction. Complex 1 is a dinuclear unit which is extended by intermolecular hydrogen-bonding interactions into a 3-D supramolecular network. Complexes 2, 4 and 6 exhibit 2-D hybrid layer motifs formed by phenyl rings bridged by infinite 1-D M–O chains, in which the H2L2− dianions act in different μ4:η6 (complex 2), μ4:η7 (complex 4) and μ4:η8 (complex 6) coordination modes. In comparison, complexes 3, 5 and 7 exhibit 3-D pillared layered networks formed by phenyl rings bridged by infinite 2-D M–O layers, in which the L4− tetraanions act in different μ6:η9 (complex 3), μ6:η9 (complex 5) and μ8:η14 (complex 7) coordination modes. The interspaces of the layer motifs in complexes 2, 4 and 6 are filled by lattice water molecules, and the channels in complexes 3 and 5 are also filled by lattice water molecules. It should be noted that the coordination modes of the sulfonate group in complexes 3 (μ3:η3), 4 (μ2:η3), 5 (μ4:η5), 6 (η2 and μ3:η4) and 7 (μ4:η5) are reported for the first time in the corresponding AE-arenesulfonates. The structural diversities and evolution of these complexes can be attributed to the nature of the metal cations, coordination modes of the sulfonate groups and the hydroxyl groups induced by the pH value. The solid-state luminescent properties demonstrate that complexes 2–7 exhibit violet emission at room temperature and the luminescent emission intensities of the H2L2− containing complexes are evidently stronger than those of the L4− containing complexes. Moreover, the complexes can sensitize Tb(III) ion to exhibit its characteristic green emission.

A three-dimensional lead(II) coordination polymer: poly[aqua-μ-imidazole-4,5-dicarboxyl­ato-lead(II)]

In the title coordination polymer, [Pb(C5H2N2O4)(H2O)](n), the Pb(II) atom is seven-coordinated by one N atom and five O atoms from four individual imidazole-4,5-dicarboxylate (HIDC2-) groups and one water molecule. It is interesting to note that the HIDC2- group serves as a bridging ligand to link the Pb(II) atoms into a three-dimensional microporous open-framework.

Syntheses, crystal structures and luminescent properties of Zn(II)/Cd(II) supramolecular complexes incorporating 4-sulfinobenzoate and its in situ oxidized ligand

Four new complexes containing d10 metal ions, 4-sulfinobenzoic acid (H2222L) and two types of N-heterocyclic ligands, namely, {[Zn(HL)2(H2O)2]n·2nH2O} (1), {[Cd(HL)2(H2O)2]n·2nH2O} (2), [CdL(2,2′-bipy)(H2O)2]2 (3) and [ZnL(4,4′-bipy)(H2O)3]n (4), have been prepared and characterized by element analysis, IR, TG, PL, and powder and single crystal X-ray diffraction. The adjacent Zn(II)/Cd(II) octahedra in complexes 1 and 2 are bridged by the sulfinate group of the HL−−− monoanion in bis-monodentate mode to form 1-D covalent chains. Two Cd(II) pentagonal bipyramids in complex 3 are bridged by a pair of L2−2− dianions in μ2-η2(carboxyl):η1(sulfinate) mode to generate a dinuclear motif. The Zn(II) octahedra in complex 4 are bridged by the 4,4′-bipy into a 1-D chain, whereas the sulfinate groups of L2−2− dianions act as terminal coordinate groups and arrange along the same side of the chain. The aforementioned four complexes are all extended into 3-D supramolecular networks through extensive hydrogen bonds together with π–π stacking interactions. When the Zn(II)/Cd(II) salts, 4,4′-bipy and H2222L are introduced to hydrothermal reactions, two new complexes of {[Zn(4,4′-bipy)2(H2O)4]n·n(SB)·4nH2O} (5) and {[Cd2(SB)2(4,4′-bipy)4(H2O)3]n·3nH2O} (6) are obtained (H22SB = 4-sulfobenzoic acid), in which the SB2−2− dianion is in situ oxidized from H2222L. Complex 5 is a 3-D host–guest supramolecular network by regarding the SB2−2− dianions as guest counteranions. In contrast, the adjacent Cd(II) cations in complex 6 are bridged by the 4,4′-bipy to generate a 1-D zig-zag chain, in which the SB2−2− dianion acts in chelating mode of carboxylate. The structure analyses of these complexes indicate that the coordination ability obeys the following sequence: sulfinate group > carboxyl group > sulfonate group. Moreover, the solid-state luminescent properties of these complexes are also investigated at room temperature.

Structural diversity of Zn(II)/Cd(II) complexes based on bis(pyridyl) ligands with a long flexible spacer: From zero-dimensional binuclear, one-dimensional chain, two-dimensional layer, to three-dimensional frameworks

Self-assembly of three bis(pyridyl) ligands with a long flexible spacer, 1,3-bis(2-pyridylaminomethyl)benzene (L1), 1,4-bis(2-pyridylaminomethyl)benzene (L2) and 1,4-bis(3-pyridylaminomethyl)benzene (L3), and group IIB metal salts (MXn, M = Zn(II) and Cd(II), X = NO3−, SO42− and ClO4−, n = 1 or 2) leads to the formation of seven metal–organic complexes, including zero-dimensional (0D) binuclear, one-dimensional (1D) chains , two-dimensional (2D) layer structures, and three-dimensional (3D) frameworks: [CdL1(SO4)(H2O)3]2 (1), [ZnL1(SO4)]n (2), [Cd(L2)1.5(NO3)2]n (3), [ZnL3(NO3)2]n (4), [Cd(L3)2(NO3)2]n (5), [Zn(L3)2]n·2nClO4 (6), and [Cd(L3)3]n·2nClO4·2nH2O (7), which have been characterized by elemental analysis, IR, PL, powder and single-crystal X-ray diffraction. Three flexible bis(pyridyl) ligands exhibit various trans-trans or cis-trans coordination modes, which results in diverse topological structures together with different anions and metal centers. Adjacent binuclear units in complex 1 linked by the sulfate-water tapes into a 2D supramolecular network. Complex 3 exhibits a 1D ladder chain structure, while complex 4 is a zig-zag chain structure. Complexes 2, 5 and 6 display (4,4) layer networks. Complex 7 is a 3D framework with pcu topology. The emission intensities of these complexes exhibit a regular change with different anions: SO42− > ClO4− > NO3−.

The first in situ organosulfonate-templated 3-fold interpenetrating framework built from rare tetrahedral [Cu4(μ4-SO4)] SBUs

An interpenetrating framework, [Cu4(SO4)(4,4-bipy)4]n·2n(C6H5SO4) [4,4′-bipyridine = 4,4′-bipy], has been successfully synthesized viahydrothermal reaction, in which the in situ generated p-hydroxybenzenesulfonate as guests are encapsulated within the channels. The tetrahedral [Cu4(μ4-SO4)] SBUs, reported for the first time in 3D architectures, are linked by parallel double 4,4′-bipys to generate a diamondoid network formed of large adamantanoid cages which causes the 3-fold interpenetration of the networks by self-clathration. Furthermore, the existence of strong π⋯π interactions between adjacent 4,4′-bipys stabilizes the interpenetrating framework. The binding energies of the Cu 2p3/2 level in the XPS spectrum are typical for a Cu(I) oxidation state. For the O1s, the XPS spectrum could be deconvoluted into three peaks corresponding to the three kinds of O atoms with different chemical environments. This work provides a method for constructing in situ organosulfonate-templated interpenetrating metal–organic frameworks.

catena-Poly­[[di­aqua­[3-(2-pyridyl)-1H-pyrazole-κN2]­cadmium(II)]-μ-squarato-κ2O:O′]

The squarate dianion in the crystal structure of the title compound, [Cd(C4O4)(C8H7N3)(H2O)2]n, links the heterocycle-chelated water-coordinated Cd atoms into a zigzag chain. The O atoms of the squarate dianions are aligned trans to each other in the octahedron surrounding the Cd atom. There are two independent square dianions and both lie on inversion centers.