A 3D Polar Nanotubular Coordination Polymer with Dynamic Structural Transformation and Ferroelectric and Nonlinear-Optical Properties

Three pairs of luminescent coordination polymers based on CoII and CdII clusters for the detection of antibiotics, pesticides and chiral nitro aromatic compounds

Three couples of coordination polymers (CPs), namely, [Co((R/S)-Hcna)₂]_n (1-D/L), [Cd₆((1R,2R/1S,2S)-cpba)₄(phen)₆(H₂O)₃]_n (2-D/L) and [Cd₂((1R,2R/1S,2S)-Hcpba)₂(phen)₂]_n (3-D/L) {(R/S)-H₂cna = (R/S)-6-(1-carboxyethoxy)-2-naphthoic acid, (1R,2R/1S,2S)-H₃cpba = (1R,2R/1S,2S)-2,2′-((5-carboxy-1,3-phenylene)bis(oxy))dipropionic acid, phen = 1,10-phenanthroline} are successfully synthesized under hydrothermal conditions. Structural analysis shows that CP 1 has a 3D 3,6-c net structure with a point symbol of (4·6²)₂(4²·6¹⁰·8³). CPs 2 and 3 are obtained under very similar reaction conditions except using different solvent ratios. The presence of the planar chelating ligand phen in CPs 2 and 3 limited the spatial growth of the structure, resulting in the formation of different 1D structures. All CPs crystallized in the chiral space group P2₁, CPs 1–3 are all SHG active. Their luminescence sensing activities for organics such as antibiotics, pesticides and nitro aromatics are also investigated. The results showed that CP 1 can effectively identify trace amounts of nitrofurans (NFs) and CP 3 has obvious recognition ability toward nitrofurans (NFs) and nitroimidazoles (NMs). Both CPs 1 and 3 could selectively detect 2,6-dichloro-4-nitroaniline (DCN). The luminescence of CPs 1 and 3 can also be quenched by (D/L)-4-nitrophenylalanine ((D/L)-NPA) and (1R,2R/1S,2S)-2-amino-1-(4-nitrophenyl)propane-1,3-diol ((1R,2R/1S,2S)-ANPO).

Three pairs of luminescent coordination polymers based on (R/S)-H₂cna and (1R,2R/1S,2S)-H₃cpba for the detection of antibiotics, pesticides and chiral nitro aromatic compounds.

Hierarchical Frameworks of Metal-Organic Cages with Axial Ferroelectric Anisotropy

Designing molecular crystals with switchable dipoles for ferroelectric applications is challenging and often serendipitous. Herein, we show a systematic approach toward hierarchical 1D, 2D and 3D frameworks that are assembled through successive linkage of metal-organic cages [Cu₆ (H₂ O)₁₂ (TPTA)₈ ]¹²⁺ with chloride ions. Their ferroelectric properties are due to the displacement of channel-bound nitrate counterions and solvated water molecules relative to the framework of cages. Ferroelectric measurements of crystals of discrete and 1D-framework assemblies showed axial ferroelectric anisotropy with high remnant polarisation. Both, the reversible formation of cage-connected networks and the observation of ferroelectric anisotropic behaviour are rare among metal-ligand cage assemblies.

A Heterobimetallic Anionic 3,6-Connected 2D Coordination Polymer Based on Nitranilate as Ligand

In order to synthesize new coordination polymers with original architectures and interesting magnetic properties, we used the nitranilate ligand (C₆O₄(NO₂)₂^2- = C₆N₂O₈^2-), derived from the dianionic ligand dhbq^2- (2,5-dihydroxy-1,4-benzoquinone = H₂C₆O₄^2-). The use of this bis-bidentate bridging ligand led to [(DAMS)₂{FeNa(C₆N₂O₈)₃}·CH₃CN]_n (1) (DAMS⁺ = C₁₆H₁₇N₂⁺ = 4-[4-(dimethylamino)-α-styryl]-1-methylpyridinium), a 2D heterometallic coordination polymer presenting an unprecedented structure for any anilato-based compound. This structural type is a 3,6-connected 2D coordination polymer derived from the well-known honeycomb hexagonal structure, where Fe(III) ions alternate with Na⁺ dimers (as Na₂O₁₂ units) in the vertices of the hexagons and with an additional [Fe(C₆N₂O₈)₃]^3- anion located in the center of the hexagons connecting the three Na⁺ dimers. The magnetic properties of compound 1 show the presence of paramagnetic isolated high spin Fe(III) complexes with a zero field splitting, |D| = 8.5 cm^-1.

Syntheses, structural diversity and photocatalytic properties of various Co(ii) coordination polymers based on a “V”-shaped 1,3-di(4′-carboxyl-phenyl)benzene acid and different imidazole bridging ligands

Various polymeric structures of complexes 1–4.

Symmetrically Related Construction and Optical Properties of Two Noncentrosymmetric 3D Iodides of d(10) Cation (Cu(+), Ag(+)) Based on the N-Benzylpyridinium and Its Supramolecular Interactions

Two noncentrosymmetric compounds, namely, [N-Bz-Py]2[Cu6I8] (1) and [N-Bz-Py]4[Ag9I13] (2) (N-Bz-Py(+) = N-benzylpyridinium), with three-dimensional open frameworks, were synthesized solvothermally via in situ benzylation of pyridine. 1 is constructed from 3-connected Cu3I7 secondary building units (SBUs) with chiral (10,3)-a topology, while the occluded N-Bz-Py(+) forms a complementary supramolecular (10,3)-a net via π-π interactions. 2 is characteristic of acentric connections of trimeric Ag3I8 and hexamer Ag6I12 SBU, while N-Bz-Py(+) in the channels aggregates into asymmetrically supramolecular chains via π-π interactions. Remarkable structural correlations imply the unique amplification and transfer of asymmetric information from V-shaped N-Bz-Py(+) to organic supramolecular nets and inorganic frameworks, which are confirmed by their second harmonic generation responses. Adsorption spectra reveal their semiconductive nature (2.52 eV for 1 and 3.02 eV for 2) and interesting reversible thermochromism for 1 based on the intermolecular charge transfer.

Solvent-controlled formation of four Ni(ii) coordination polymers based on a flexible bis(imidazole) ligand: syntheses, structural diversification, properties

Four new isomeric Ni(ii) coordination polymers with different architectures and properties were successfully synthesized by tuning the solvent media.

Syntheses, structures, topologies, and luminescence properties of four coordination polymers based on bifunctional 6-(4-pyridyl)-terephthalic acid and bis(imidazole) bridging linkers

Four CPs, with the structure ranged from 2D sheet to 3D 3-fold penetrated net, have been designed with the mixed-ligand strategy of bifunctional 6-(4-pyridyl)-terephthalic acid and bis(imidazole) bridging linkers.

Syntheses, structures and luminescent properties of six divalent metal terephthalate coordination polymers based on three new flexible bis(imidazole) ligands

Six coordination polymers based on terephthalate and one of three bis(imidazole) ligands are reported.

Structural diversity and magnetic properties of six metal–organic polymers based on semirigid tricarboxylate ligand of 3,5-bi(4-carboxyphenoxy)benzoic acid

Six new metal–organic complexes with structural diversities constructed from 3,5-bi(4-carboxyphenoxy)benzoic acid and metal ions were synthesized and characterized.

Syntheses, structures, and magnetic properties of six coordination polymers based on 4,5-di(4′-carboxylphenyl)phthalic acid and different bis(imidazole) bridging linkers

Six multi-dimensional metal–organic polymers based on 4,5-di(4′-carboxylphenyl)phthalic acid and bis(imidazole) bridging linkers were synthesized and characterized.

First one-dimensional homochiral stairway-like Cu(II) chains: crystal structures, circular dichroism (CD) spectra, ferroelectricity and antiferromagnetic properties

The reactions of enantiopure chiral ligands (+)/(−)-4,5-pinenepyridyl-2-pyrazine (LS/LR) with CuCl2·2H2O in CH3OH/CH2Cl2 solution led to the formations of one-dimensional homochiral enantiomeric pairs with the formula [Cu(LR/S)Cl2]n·2H2O (R-1 and S-1, the isomers containing the LR and LS ligands, respectively). The circular dichroism (CD) spectra verified their chiroptical activities and enantiomeric natures. Their structures have been determined by X-ray single-crystal analyses, showing stairway-like and mirror-symmetric features, which represent the first examples of homochiral metal complexes with stairway-like structures. The ferroelectric property measurement indicated that R-1 exhibits ferroelectricity with the remnant polarization (Pr) value of 0.02 μC cm−2 under an applied electric field of 6.1 kV cm−1 at room temperature. The magnetic investigation of R-1 showed a weak intrachain antiferromagnetic coupling between Cu(II)–Cu(II) ions mediated by pyrazine, which can be interpreted by a spin-polarization mechanism. All these results suggested that R-1 and S-1 are potential multifunctional molecule-based materials combining optical activity, ferroelectricity and magnetism within one molecule.

Two Zn(II) metal-organic frameworks with coordinatively unsaturated metal sites: structures, adsorption, and catalysis

Assembly of Zn(NO(3))(2) with the tripodal ligand H(3)TCPB (1,3,5-tri(4-carboxyphenoxy)benzene) affords two porous isoreticular metal-organic frameworks, [Zn(3)(TCPB)(2)⋅2DEF]⋅3DEF (1) and [Zn(3)(TCPB)(2)⋅2H(2)O]⋅2H(2)O⋅4DMF (2). Single-crystal X-ray diffraction analyses reveal that 1 crystallizes in the monoclinic space group P2(1)/c and possesses a 2D network containing 1D microporous opening channels with an effective size of 3.0×2.9 Å(2), whereas 2 crystallizes in the trigonal space group P3c1 and also possesses a 2D network containing 1D channels, with an effective aperture of 4.0×4.0 Å(2). TOPOS analysis reveals that both 1 and 2 have a (3,6)-connected network topology with the Schläfli symbol of (4(3)⋅6(12)) (4(3))(2). According to the variable-temperature powder X-ray diffraction patterns, the solid phase of 1 can be converted into that of 2 during a temperature-induced dynamic structural transformation, thus indicating that the framework of 2 represents the most thermally stable polymorph. Desolvated 2 exhibits highly selective adsorption behaviors toward H(2)/N(2), CO(2)/N(2), and CO(2)/CH(4); furthermore, it displays size-selective catalytic activity towards carbonyl cyanosilylation and Henry (nitroaldol) reactions.