Wayne Hsu

Structure-directing roles of auxiliary polycarboxylate ligands in the formation of Zn(II) and Cd(II) coordination polymers based on a flexible N,N′-di(3-pyridyl)dodecanediamide

Reactions of the flexible N,N′-di(3-pyridyl)dodecanediamide (L) with Zn(II) and Cd(II) metal salts in the presence of different polycarboxylic acids under hydrothermal conditions afforded five new coordination polymers, [Zn(2,4-PDC)(L)(H2O)]∞ (2,4-H2PDC = 2,4-pyridinedicarboxylic acid), 1, {[Zn(1,3,5-HBTC)(L)]·2H2O}∞ (1,3,5-H3BTC = 1,3,5-benzenetricarboxylic acid), 2, {[Zn(3,4-PDC)(L)]·0.5L}∞ (3,4-H2PDC = 3,4-pyridinedicarboxylic acid), 3, {[Cd(1,2-BDC)(L)(H2O)]·0.5L}∞ (1,2-H2BDC = 1,2-benzenedicarboxylic acid), 4, and {[Cd(1,3,5-HBTC)(L)1.5]·2H2O}∞, 5, which have been structurally characterized by X-ray crystallography. Complexes 1 and 2 manifest quintuple and double helices formed by zinc ions and L ligands, which are supported by 2,4-PDC2− and 1,3,5-HBTC2− anions, respectively, to construct the rare single-walled metal–organic nanotubes. Complex 3 shows 1D fish-bone chains and complexes 4 and 5 display 2D pleated grids with helical and looped carboxylate chains, respectively, supported by the L ligands. Complexes 1–3 represent a unique example of the polycarboxylate ligands showing a significant effect on folding and unfolding of the Zn(II) helical coordination polymers, and they are also important in determining the number of helices. The L ligands in 1, 2 and 4 adopt a bidentate bonding mode, and a unique monodentate bonding mode for the dipyridyl amide ligand is found in 3 and 5, resulting in various types of ligand conformations.

Structural diversity of Ni(II) coordination polymers containing dipyridyl amide and angular dicarboxylate ligands: synthesis, structures and magnetism

Four new Ni(II) coordination polymers containing dipyridyl amide and angular dicarboxylate ligands, {[Ni(L1)(MBA)]·2H2O}∞ [L1 = N,N′-di(4-pyridyl)-adipoamide; H2MBA = diphenylmethane-4,4′-dicarboxylic acid], 1, {[Ni(L1)(OBA)]·H2O}∞ [H2OBA = 4,4′-oxybis(benzoic acid)], 2, {[Ni(L1)(SDA)]·2H2O}∞ (H2SDA = 4,4′-sulfonyldibenzoic acid), 3, and {[Ni2(L2)(SDA)2]·6H2O}∞ [L2 = N,N′-di(4-pyridyl)suberoamide], 4, have been synthesized by hydrothermal reactions and were structurally characterized by single crystal X-ray diffraction analyses. Complex 1 is a 1D → 2D polycatenane derived from the helical channels, and the 2D layers are further mutually interdigitated, whereas complex 2 forms 2D rhombic grids with the (6,4) topology, which are interwoven with each other to give a two fold 2D → 2D interpenetrating net. Complex 3 shows the 1D looped chain structure, and complex 4 shows 2D layers which catenate to each other to form a 2D → 3D inclined polycatenation framework with the new (42·68·8·104)(4)2 topology. The C–X–C (X = CH2, 1; O, 2; and SO2, 3 and 4) angles are important in determining the structural diversity. Complex 1 exhibits a different magnetic reaction in the ZFC and FC processes, revealing the existence of a meta-state of ferromagnetic ordering, whereas the activation energies of spin–orbit coupling and antiferromagnetic interaction of complexes 2–4 are directed by the N⋯N and Ni⋯Ni distances, respectively.

Structural directing roles of isomeric phenylenediacetate ligands in the formation of coordination networks based on flexible N,N′-di(3-pyridyl)suberoamide

Reactions of the flexible N,N′-di(3-pyridyl)suberoamide (L) with Cu(II) salts in the presence of the isomeric phenylenediacetic acids under hydrothermal conditions afforded three new coordination networks, {[Cu(L)(1,2-pda)]·H2O}n (1,2-H2pda = 1,2-phenylenediacetic acid), 1, {[Cu(L)(1,3-pda)]·2H2O}n (1,3- H2pda = 1,3-phenylenediacetic acid), 2, and {[Cu(L)(1,4-pda)]·2H2O}n (1,4-H2pda = 1,4-phenylenediacetic acid), 3, which have been structurally characterized by X-ray crystallography. Complex 1 forms a single 3,5-coordinated 3D net with the (42·65·83)(42·6)-3,5T1 topology, which can be further simplified as a 6-coordinated (412·63)-pcu topology. Complex 2 is a 5-fold interpenetrated 3D structure with the (65·8)-cds topology, which exhibits the maximum number of interpenetration presently known for cds and complex 3 is the first 1D self-catenated coordination network. The ligand isomerism of the phenylenediacetate ligands is important in determining the structural types of the Cu(II) coordination networks based on the flexible L ligands.

Diverse Ag(I) complexes constructed from asymmetric pyridyl and pyrimidyl amide ligands: roles of Ag⋯Ag and π–π interactions

Reactions of silver(I) salts with the isomeric pyridyl amide ligands methyl-4-(pyridin-2-ylcarbamoyl)benzoate (L1), methyl-4-(pyridin-3-ylcarbamoyl)benzoate (L2) and methyl-4-(pyridin-4-ylcarbamoyl)benzoate (L3) and the pyrimidyl amide ligand methyl-4-(pyrimidin-2-ylcarbamoyl)benzoate (L4) afforded the complexes Ag4(L1)4(NO3)4, 1, [Ag(L2)2][Ag(NO3)2], 2, [Ag(L2)2](ClO4), 3, [Ag(L2)2](ClO4)·2CH3CN, 4, [Ag(L3)2](NO3), 5, [Ag(L3)2](ClO4)·CH3CN, 6, and [Ag(L4)2](X) (X = ClO4−, 7; BF4−, 8; PF6−, 9), which were structurally characterized by X-ray crystallography. The L1–L3 ligands in 1–6 adopt monodentate bonding modes, which coordinate to the metal centers through the pyridyl nitrogen atoms, whereas the L4 ligands of 7–9 adopt a bidentate mode, featuring chelation through one pyrimidyl nitrogen atom and the amide oxygen atom. All nine complexes adopt discrete structures with 1 being tetranuclear and 2–9 being mononuclear. Moreover, Ag⋯Ag short contacts, π⋯π stacking interactions and/or Ag⋯O interactions are found in these complexes which extend the dimensionalities of the structures. The changes of the donor atom positions and counteranions significantly affect the supramolecular structures of these complexes and the L1–L4 ligands are sufficiently flexible to adopt the cis and/or trans conformations.

Entanglement in Co(II) coordination networks: polycatenation from single net to 2-fold and 3-fold interpenetrated nets

The synthesis, structures and properties of six coordination networks based on N,N′-di(4-pyridyl)suberoamide (L) and angular dicarboxylate ligands, {[Co(L)(MBA)]·2H2O}n (H2MBA = diphenylmethane-4,4′-dicarboxylic acid), 1, {[Co(L)0.5(MBA)]·CH3OH}n, 2, [Co(L)0.5(MBA)]n, 3, {[Co2(L)(OBA)2]·7CH3OH}n [H2OBA = 4,4′-oxybis(benzoic acid)], 4, {[Co(L)(hfipbb)]·2H2O}n [H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid)], 5, and {[Co(L)(SDA)]·H2O}n (H2SDA = 4,4′-sulfonyldibenzoic acid), 6, are reported. Complex 1 is a 1D → 2D polycatenane derived from the helical channels, whereas both complexes 2 and 3 show 2D layers with the (42·68·8·104)(4)2-2,6L1 topology, which are further entangled to form a 2-fold 2D → 2D interpenetration network and a 2D → 3D inclined polycatenation network, respectively, and complex 4 shows a 3-fold 3D → 3D interpenetration network with the (412·63)-pcu topology. The unusual topological features of 5 and 6 consist of 2- and 3-fold interpenetrated layers with the (44·62)-sql topology, which are further catenated to the two such adjacent sheets in parallel and uniform fashions to give 2D → 3D polycatenated networks. Complexes 1, 5 and 6 represent unique examples that the angular dicarboxylate ligands show significant effect on the degree of interpenetration of polycatenation coordination networks with interpenetrating modes. The CO2 capture is preferable to N2 and H2 in the gas sorption for the desolvated product of 4.

Crystal-to-crystal transformations and photoluminescence changes in the Cu(I) coordination networks based on a formamidinate ligand

One-pot solvothermal reactions of 4-aminopyridine and triethylorthoformate with Cu(O2CCH3)2 in acetone (ACT), dimethylformamide (DMF), tetrahydrofuran (THF), methanol (MeOH) and ethanol (EtOH) afforded 2D coordination networks, anti-{[Cu(4-pyf)]·ACT}n, 1a, (4-Hpyf = N,N′-bis(pyridine-4-yl)formamidine), anti-{[Cu(4-pyf)]·DMF}n, 1b, anti-{[Cu(4-pyf)]·THF]}n, 1c, syn-{[Cu4(4-pyf)4]·2MeOH}n, 2a, and syn-{[Cu4(4-pyf)4]·2EtOH}n, 2b, whereas the reaction of Cu(O2CCH3)2, 4-aminopyridine, triethylorthoformate and CuX2 (X = BF4− and ClO4−) in ethanol gave the 3D coordination networks syn-{[Cu3(4-pyf)2](BF4)·2H2O·EtOH}n, 3a, and syn-{[Cu3(4-pyf)2](ClO4)·EtOH}n, 3b, which were characterized by X-ray crystallography. Complexes 1a–3b are the first 2D and 3D coordination networks showing closed-shell Cu(I)–Cu(I) interactions that are supported by the formamidinate ligands. Reversible crystal-to-crystal transformations were observed for the 2D anti- and syn-coordination networks upon solvent exchange. Irreversible anti to syn crystal-to-crystal transformations can be shown upon solvent removal and the important intermediate, syn-{[Cu4(4-pyf)4]·2THF}n, 2c, which verifies the temperature-dependent transformation, was structurally characterized. The configurations of the structures have significant influence on the emission properties. While the syn-complexes show broad emission bands, those of the anti-complexes are not detectable, indicating that cuprophilicity is unlikely to play significant roles in determining the emission of 1a–3b. The 2D anti- and syn-complexes that show outwardly dangling pyridyl rings may adsorb Cd salts through Cd–N interactions.

Stepwise formation of heteronuclear coordination networks based on quadruple-bonded dimolybdenum units containing formamidinate ligands

Reactions of [Mo2(4-pyf)4] (4-Hpyf = 4-pyridylformamidine) with HgX2 (X = Cl, Br and I) afforded the first 2D and 3D heteronuclear coordination networks based on quadruple-bonded dimolybdenum units.

Hg(II) Coordination Polymers Based on N,N'-bis(pyridine-4-yl)formamidine

Reactions of N,N’-bis(pyridine-4-yl)formamidine (4-Hpyf) with HgX2 (X = Cl, Br, and I) afforded the formamidinate complex {[Hg(4-pyf)2]·(THF)}n, 1, and the formamidine complexes {[HgX2(4-Hpyf)]·(MeCN)}n (X = Br, 2; I, 3), which have been structurally characterized by X-ray crystallography. Complex 1 is a 2D layer with the {44·62}-sql topology and complexes 2 and 3 are helical chains. While the helical chains of 2 are linked through N–H···Br hydrogen bonds, those of 3 are linked through self-complementary double N–H···N hydrogen bonds, resulting in 2D supramolecular structures. The 4-pyf- ligands of 1 coordinate to the Hg(II) ions through one pyridyl and one adjacent amine nitrogen atoms and the 4-Hpyf ligands of 2 and 3 coordinate to the Hg(II) ions through two pyridyl nitrogen atoms, resulting in new bidentate binding modes. Complexes 1–3 provide a unique opportunity to envisage the effect of the halide anions of the starting Hg(II) salts on folding and unfolding the Hg(II) coordination polymers. Density function theory (DFT) calculation indicates that the emission of 1 is due to intraligand π→π * charge transfer between two different 4-pyf- ligands, whereas those of 2 and 3 can be ascribed to the charge transfer from non-bonding p-type orbitals of the halide anions to π * orbitals of the 4-pyf- ligands (n→π *). The gas sorption properties of the desolvated product of 1 are compared with the Cu analogues to show that the nature of the counteranion and the solvent-accessible volume are important in determining their adsorption capability.

Dinitrogen-supported coordination polymers

The one-pot solvothermal reactions of 3- and 4-(aminomethyl)pyridine with triethyl orthoformate and Cu(O2CCH3)2 in methanol saturated with dinitrogen afforded the first examples of coordination polymers that are supported by dinitrogen, namely [Cu2.5(3-mpyf)(N2)1.5]n [3-Hmpyf = N,N′-bis(pyridine-3-ylmethyl)formamidine], 1, and {[Cu3(4-Hmpyf)(N2)3]·(CH3OH)}n [4-Hmpyf = N,N′-bis(pyridine-4-ylmethyl)formamidine], 2. The dinitrogen anions of 1 adopt the end-on-dinuclear (μ-η1:η1) bonding mode, resulting in a 4,4-connected binodal net with the new (53·73)2(54·82) topology, and those of 2 display both end-on-dinuclear and end-on-trinuclear (μ-η1:η1:η1) bonding modes, forming a 3,8-connected binodal net with the rare (53)4(58·64·78·84·94)2-3,8T16 topology.

4,4'-[Oxalylbis(azanediyl)]dipyridinium bis(perchlorate).

In the title molecular salt, C12H12N4O2 2+·2ClO4 −, the complete cation is generated by crystallographic inversion symmetry. In the crystal, the cations and anions are linked via N—H⋯O and N—H⋯(O,O) hydrogen bonds, forming a three-dimensional framework.