Jin-Zhong Gu

Synthesis, structural versatility, luminescent and magnetic properties of a series of coordination polymers constructed from biphenyl-2,4,4′-tricarboxylate and different N-donor ligands

Eight new coordination polymers [Mn(H2btc)2(4,4′-bpy)2]n (1), {[Cd(Hbtc)(phen)(H2O)]·H2O}n (2), [Pb(Hbtc)(phen)]n (3), {[Cd3(btc)2(H2O)5]·4H2O}n (4), {[Cd3(btc)2(phen)2(H2O)]·H2O}n (5), [Mn3(btc)2(2,2′-bpy)2]n (6), {[Ni3(btc)2(4,4′-bpy)2.5(μ2-H2O)(H2O)3]·3H2O}n (7), and {[Co2(btc)(μ3-OH)(μ2-H2O) (8), were assembled from different metal(II) chlorides and biphenyl-2,4,4′-tricarboxylic acid (H3btc) as a main building block, and various aromatic N-donors (phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine) as supporting ligands. By adjusting the reaction pH, H3btc undergoes a partial deprotonation to give the H2btc− form in 1, and the Hbtc2− moiety in 2 and 3, and the fully deprotonated btc3− form in 4–8. All the products were fully characterized by single crystal X-ray diffraction analysis. Compounds 1 and 2 possess the double helical chain and wheel chain 1D coordination networks, respectively, which are further extended into the 3D supramolecular architectures via hydrogen bonds. The 2D and 3D metal–organic networks of 6 and 3 were topologically classified, revealing the trinodal 3,6,6-connected and uninodal 4-connected nets with the 3,6,6L3 and sra topologies, respectively. Compounds 4, 5, 7, and 8 feature the very complex 3D metal–organic framework structures, generating either pentanodal 3,4,5,6,6- (4), 3,3,4,5,5- (5), and 4,4,4,5,6-connected (7), or tetranodal 3,5,6,6-connected (8) underlying nets with the hitherto undocumented topologies. The obtained data revealed that different coordination modes of the H2btc−/Hbtc2−/btc3− ligands and the resulting crystal architectures depend on a variety of factors, such as the solution pH and the nature of metal ions and N-donor auxiliary ligands. Magnetic susceptibility measurements indicate that 1 and 8 show a dominating ferromagnetic coupling, while 6 and 7 exhibit an antiferromagnetic coupling between the metal centers. Furthermore, thermal stability of 1–8 and luminescent properties of 2–5 were also studied and discussed.

A series of mixed-ligand 2D and 3D coordination polymers assembled from a novel multifunctional pyridine-tricarboxylate building block: hydrothermal syntheses, structural and topological diversity, and magnetic and luminescent properties

A series of novel mixed-ligand coordination polymers, namely, {[Cd2(μ4-L)(μ3-OH)(phen)2]·2H2O}n (1), {[Mn3(μ5-L)2(phen)2(H2O)]·H2O}n (2), [Cd2(μ3-L)(H2biim)2(μ2-Hbiim)]n (3), {[Pb2(μ4-L)(μ4-bpdc)0.5(phen)2]·H2O}n (4), [Cd2(μ5-L)(μ2-bpdc)0.5(phen)2]n (5), and [Zn2(μ4-L)(μ2-bpdc)0.5(py)2]n (6), was hydrothermally synthesized using 4-(5-carboxypyridin-2-yl)isophthalic acid (H3L) as a new and virtually unexplored multifunctional pyridine-tricarboxylate building block, along with various auxiliary ligands {phen = 1,10-phenanthroline, H2biim = 2,2′-biimidazole, H2bpdc = 4,4′-biphenyldicarboxylic acid, and py = pyridine}. All the products 1–6 were characterized by IR spectroscopy, elemental, thermogravimetric, and single-crystal X-ray diffraction analyses. Compounds 1, 3, and 5 reveal 2D metal–organic layers with the kgd, fes, and 3,4,5L5 topology, respectively, whereas the metal–organic frameworks (MOFs) 2, 4, and 6 disclose 3D underlying nets with the unique (2, 4) or ins (6) topology. The results indicate that the nature of the metal(II) ion and type of auxiliary ligand play a significant role in determining the dimensionality, topology and other structural features of the obtained products. Luminescent (for 1 and 3–6) and magnetic (for 2) properties were studied and discussed.

Lanthanide coordination polymers based on 5-(2′-carboxylphenyl) nicotinate: syntheses, structure diversity, dehydration/hydration, luminescence and magnetic properties

Twelve lanthanide coordination polymers associated with the organic ligand 5-(2′-carboxylphenyl) nicotinic acid (H2cpna): {[Ln(Hcpna)(cpna)(phen)]·H2O}n (Ln = Sm (1), Tb (2), Ho (3), phen = 1,10-phenanthroline), {[Sm(Hcpna)(cpna)(phen)]·2H2O}n (4), {[Ln2(cpna)3(H2O)3]·4H2O}n (Ln = Y (5), Tb(6), Dy (7), Ho (8)), [Lu2(cpna)3(H2O)2]n (9), {[Y2(cpna)3(phen)2(H2O)]·H2O}n (10), and [Ln(cpna)(phen)(NO3)]n (Ln = Tm (11), Lu (12)) have been prepared by hydrothermal methods and structurally characterized. The structure analyses reveal that complexes 1–3 are isostructural and possess unique three-dimensional (3D) frameworks based on the dodecanuclear Sm/Tb/Ho macrocycles. Complex 4 exhibits a one-dimensional (1D) wheel-chain structure, which further builds three-dimensional (3D) supramolecular architecture via O–HN hydrogen-bonding interactions. Complexes 5–8 are also isostructural and display three-dimensional (3D) open frameworks, which possess two types of channels along the a- and b-axis, respectively. Complexes 9 and 10 feature three-dimensional (3D) frameworks and are created from tetranuclear and dinuclear units, respectively. Complexes 11 and 12 are isostructural and demonstrate one-dimensional (1D) double chain structures, which further build three-dimensional (3D) supramolecular architecture via C–H···O hydrogen-bonding. The results show that the pH value of the reaction system, anion, auxiliary ligand and lanthanide contraction play a significant role in determining the structures of the complexes. In addition, the results of luminescent measurements for compounds 2 and 6 in the solid state at room temperature indicate that the different types of structures have a dissimilar influence on their characteristic luminescence. The magnetic properties of compounds 1, 3, 4, 7 and 11 have been investigated. Furthermore, thermal stabilities for 1–12 and the dehydration/hydration properties of compound 6 have also been studied.

A variety of metal-organic and supramolecular networks constructed from a new flexible multifunctional building block bearing picolinate and terephthalate functionalities: hydrothermal self-assembly, structural features, magnetic and luminescent properties

A novel flexible multifunctional building block (H3L) bearing picolinate and terephthalate functionalities was designed and applied for the hydrothermal self-assembly generation of a series of coordination compounds [Co(H2L)2(H2O)2] (1), [M(HL)(H2O)]n {M = Cd (2) and Mn (3)}, {[Mn1.5(L)(phen)(H2O)2]·H2O}n (4), [Zn3(L)2(H2O)6]n (5), and {[Zn3(L)2(py) (H2O)4]·4H2O}n (6) {wherein H3L = 2-(4-carboxypyridin-3-yl)-terephthalic acid, phen = 1,10-phenanthroline, py = pyridine}. All the obtained products 1–6 were fully characterized by IR spectroscopy, elemental, thermogravimetric, powder and single-crystal X-ray diffraction analyses. By adjusting the molar ratio of NaOH and H3L ligand, the latter becomes partially deprotonated to form the H2L− blocks in 1 and HL2− moieties in 2 and 3, or completely deprotonated to create the L3− units in 4–6. The structures of the obtained compounds range from a discrete 0D monomer 1 and 1D coordination polymers 4 and 5 to 2D coordination polymers 2 and 3, and an intricate 3D metal–organic framework 6; their detailed topological classification was also performed. The structures of 1–5 are further extended [0D → 3D (1), 1D → 3D (4, 5), and 2D → 3D (2, 3)] into supramolecular networks by means of multiple hydrogen bonds. The results reveal that the nature of metal(II) ion, molar ratio between NaOH and H3L ligand, and the presence (optional) of auxiliary ligand play a significant role in determining dimensionality, topology and other structural features of the obtained products. Magnetic susceptibility measurements indicate that compounds 3 and 4 have dominating antiferromagnetic couplings between metal centers. Furthermore, luminescent properties of 2, 5, and 6 were also investigated.

Exploring biphenyl-2,4,4′-tricarboxylic acid as a flexible building block for the hydrothermal self-assembly of diverse metal–organic and supramolecular networks

Biphenyl-2,4,4′-tricarboxylic acid (H3btc) was applied as a principal but still little explored building block for the synthesis of nine new coordination compounds, namely, [Zn(H2btc)(phen)2][H2btc]·H2O (1), [M(H2btc)2(H2biim)2] {M = Co (2) and Cd (3)}, [Ni(Hbtc)(phen)2(H2O)]·2H2O (4), [Cd2(μ4-btc)(μ2-Cl)(phen)2]n (5), [Ni3(μ4-btc)2(μ2-H2O)2(py)4(H2O)2]n (6), {[Co3(μ4-btc)2(μ2-H2O)2(py)4(H2O)2]·(py)2}n (7), {[Co3.5(μ6-btc)2(μ3-OH)(py)2(H2O)3]·H2O}n (8), and {[Pb3(μ6-btc)2(H2O)]·H2O}n (9). These products were easily generated by a hydrothermal self-assembly method from the corresponding metal(II) chlorides, H3btc, and various N-donor ancillary ligands, selected from 1,10-phenanthroline (phen), 2,2′-biimidazole (H2biim), or pyridine (py). Compounds 1–9 were characterized by IR spectroscopy, elemental, thermogravimetric, powder and single-crystal X-ray diffraction analyses. Their structures range from the intricate 3D metal–organic frameworks (MOFs) 6–9 to the 2D coordination polymer 5 and the discrete 0D monomers 1–4. Such a structural diversity is guided by the type of metal(II) node, level of the deprotonation of biphenyl-2,4,4′-tricarboxylic acid, and kind of ancillary ligand. The structures of 1–4 are further extended [0D → 2D (1) and 0D → 3D (2–4)] into various H-bonded networks. Both the supramolecular (in 1–4) and coordination (in 5–9) underlying networks were classified from the topological viewpoint, disclosing the distinct 4,5L64 (in 1), pcu (in 2 and 3), sxb (in 4), hcb (in 5), and wei (in 6 and 7) topological nets, whereas topologically unique frameworks were identified in MOFs 8 and 9. The magnetic (for 6–8) and luminescence (for 1, 3, 5, and 9) properties were also studied and discussed.

Exploring 4-(3-carboxyphenyl)picolinic acid as a semirigid building block for the hydrothermal self-assembly of diverse metal–organic and supramolecular networks

4-(3-Carboxyphenyl)picolinic acid (H2cppa) was applied as a new and virtually unexplored building block for the synthesis of eleven new coordination compounds, namely [M(Hcppa)2(H2O)2]·2H2O {M = Ni (1) and Zn (2)}, [M(μ3-cppa)(H2O)2]n {M = Ni (3) and Co (4)}, {[Co(μ-cppa)(2,2′-bipy)(H2O)]·H2O}n (5), [Zn(μ-cppa)(2,2′-bipy)]n (6), [M(μ-cppa)(phen)(H2O)]n {M = Co (7), Zn (8), Mn (9), and Cu (10)}, and {[Cd3(μ3-cppa)3(phen)2]·4H2O}n (11). All these compounds were generated by a hydrothermal self-assembly method using the corresponding metal(II) chlorides, H2cppa, and two types of N-donor ancillary ligands, selected from 2,2′-bipyridine (2,2′-bipy) or 1,10-phenanthroline (phen). The obtained products 1–11 were characterized by standard methods, including IR spectroscopy, elemental and thermogravimetric analyses, and powder and single-crystal X-ray diffraction. They represent the first structurally characterized compounds derived from H2cppa. The structures of 1–11 vary from a complex 3D metal–organic framework (MOF) 11 to 2D coordination polymers 3 and 4, 1D coordination polymers 5–10, and discrete 0D monomers 1 and 2. Such a structural diversity is guided by the nature of the metal(II) node, level of deprotonation of 4-(3-carboxyphenyl)picolinic acid, and type of applied ancillary ligand. In addition, the structures of 1, 2, 5, and 7–10 are further extended [0D → 3D (1 and 2), 1D → 2D (5), and 1D → 3D (7–10)] into various H-bonded supramolecular networks. Both the supramolecular (in 1, 2, 5, and 7–10) and metal–organic (in 3, 4, 6, and 11) underlying networks were analyzed and classified from the topological viewpoint, revealing the distinct pcu (in 1 and 2), fes (in 3 and 4), gek1 (in 5), 2C1 (in 6), and srs (in 7–10) topological nets, whereas a topologically unique framework was identified in MOF 11. The magnetic behavior of 3–5, 7, 9, and 10 and luminescence properties of 2, 6, 8, and 11 were also investigated and discussed.

Nickel(II) and manganese(II) metal–organic networks driven by 2,2′-bipyridine-5,5′-dicarboxylate blocks: synthesis, structural features, and magnetic properties

Two compounds, namely a 2D coordination polymer {[Ni(µ3-bpdc)(H2O)]·H2O}n (1) and a 3D metal–organic framework (MOF) [Mn(µ4-bpdc)(phen)]n (2), were generated by a hydrothermal self-assembly from the corresponding metal(II) chlorides, 2,2′-bipyridine-5,5′-dicarboxylic acid (H2bpdc) as a main building block, and an optional ancillary 1,10-phenanthroline (phen) ligand. The obtained products were characterized by IR spectroscopy, elemental, thermogravimetric, powder and single-crystal X-ray diffraction analyses. Compound 1 possesses a 2D double-layered network with the plane SP KIa topology defined by the point symbol of (82.10), which is further extended into a 3D supramolecular architecture via hydrogen bonds. MOF 2 features a 3D net with the pts topology and point symbol of (42.84). The magnetic properties for both compounds were also investigated, indicating antiferromagnetic interactions between the adjacent metal ions.Graphical AbstractTwo 2D and 3D metal–organic networks driven by a multifunctional building block were self-assembled and fully characterized; their structural, topological, and magnetic features were investigated.

Bringing 5-(3,4-dicarboxylphenyl)picolinic acid to crystal engineering research: hydrothermal assembly, structural features, and photocatalytic activity of Mn, Ni, Cu, and Zn coordination polymers

5-(3,4-Dicarboxylphenyl)picolinic acid (H3dppa) was applied as a novel tricarboxylic acid block with phthalate and picolinate functionalities for the aqueous-medium assembly of seven new coordination compounds, namely, [Mn2(μ-Hdppa)2(phen)2(H2O)2] (1), {[Mn(μ-Hdppa)(2,2′-H2biim)(H2O)]·H2O}n (2), [Ni(Hdppa)(phen)2]·4H2O (3), {[Ni(μ-Hdppa)(μ-4,4′-bipy)(H2O)]·H2O}n (4), {[Cu3(μ3-dppa)(μ-Hdppa)(phen)4]2[Cu(μ-Hdppa)2]·10H2O}n (5), {[Ni3(μ-dppa)2(μ-1,4-bpb)2(H2O)6]·4H2O}n (6), and {[Zn3(μ4-dppa)2(phen)2(H2O)2]·4H2O}n (7). These products 1–7 represent the first structurally characterized examples of the coordination compounds derived from H3dppa. Compounds 1–7 were assembled in the presence of various N-donor supporting ligands acting as crystallization mediators, which were selected from 1,10-phenanthroline (phen), 2,2′-biimidazole (H2biim), 4,4′-bipyridine (4,4′-bipy), or 1,4-bis(pyrid-4-yl)benzene (1,4-bpb). Full characterization of 1–7 by IR spectroscopy, thermogravimetric (TGA), elemental, and topological analyses, as well as powder (PXRD) and single-crystal X-ray diffraction, was performed. The structural types range from the discrete 0D complexes (1 and 3) and 1D coordination polymers with a 2C1 topology (2, 5, and 6) to the 2D metal–organic layers with an sql topology (4 and 7). The structural diversity of 1–7 is driven by various factors, including the metal(II) node nature, deprotonation degree of H3dppa, or type of crystallization mediator. The magnetic properties of 1, 2, 4, and 6 were studied and modeled, revealing antiferromagnetic (in 1, 2, and 6) or ferromagnetic (in 4) interactions between adjacent metal(II) centers. The luminescence of 7 was also investigated. Moreover, the photocatalytic activity of 1–7 was studied for the degradation of methylene blue as a model dye pollutant, disclosing that the nickel(II) coordination polymer 4 is the most active catalyst. The observed catalytic activity of 1–7 correlates well with their band gap energies determined by the UV-diffuse reflectance method.

Exploring 5-fluoronicotinic acid as a versatile building block for the generation of topologically diverse metal–organic and supramolecular Ni, Co, and Cd networks

Five new coordination compounds, namely [Ni(5-Fnic)2(μ2-H2O)0.5]n (1), [Co(5-Fnic)2(H2biim)]n (2), {[Cd(5-Fnic)2(phen)]·2H2O}n (3), [Cd(5-Fnic)2(H2biim)2] (4), and [Co(5-Fnic)2(H2O)4] (5), were generated by hydrothermal methods from the metal(II) nitrates, 5-fluoronicotinic acid (5-FnicH), and an optional ancillary 1,10-phenanthroline (phen) or 2,2′-biimidazole (H2biim) ligand. All the products 1–5 were characterized by IR spectroscopy, elemental, thermogravimetric, and single-crystal X-ray diffraction analyses. Their structures range from the intricate 3D metal–organic framework (MOF) 1 to the 1D coordination polymers 2 and 3, and the discrete 0D monomers 4 and 5. The structures of 2–5 are further extended [1D → 2D (2), 1D → 1D (3), 0D → 1D (4), and 0D → 3D (5)] into various H-bonded networks. The topological analysis of the underlying coordination (in 1) and H-bonded (in 2–5) nets revealed a very rare 3,6T10 MOF topology in 1, a parallel 2D + 2D interpenetration of the sql nets in 2, a topologically unique double chain in 3, a simple 2C1 topology in 4, and a pcu (alpha-Po primitive cubic) topology in 5. The magnetic (for 1 and 2) and luminescent (for 3 and 4) properties were also investigated and discussed.

Triaqua­(1,10-phenanthroline-2,9-dicarboxyl­ato)cobalt(II) dihydrate

The title compound, [Co(C14H6N2O4)(H2O)3]·2H2O, has twofold crystallographic symmetry. The CoII atom is in a distorted pentagonal-bipyramidal coordination environment with two N atoms and two O atoms from a tetradentate 1,10-phenanthroline-2,9-dicarboxylate ligand and one O atom from a water molecule forming the pentagonal plane, and two O atoms from two water molecules occupying axial positions. In the crystal, adjacent molecules are linked by O—H⋯O hydrogen bonds, forming a three-dimensional network.