Guest-Stimulated Nonplanar Porphyrins in Flexible Metal-Organic Frameworks.

Nonplanar porphyrins with out-of-plane distortions play crucial roles in many biological functions and chemical applications. The artificial construction of nonplanar porphyrins usually involves organic synthesis and modification, which is a highly comprehensive approach. However, incorporating porphyrins into guest-stimulated flexible systems allows to manipulate the porphyrin distortion through simple ad/desorption of guest molecules. Here, a series of porphyrinic zirconium metal-organic frameworks (MOFs) is reported that exhibit guest-stimulated breathing behavior. X-Ray diffraction analysis and skeleton deviation plots confirm that the material suffers from porphyrin distortion to form a ruffled geometry under the desorption of guest molecules. Further investigation reveals that not only the degree of nonplanarity can be precisely manipulated but also the partial distortion of porphyrin in a single crystal grain can be readily achieved. As Lewis acidic catalyst, the MOF with nonplanar Co-porphyrin exhibits active properties in catalyzing CO2 /propylene oxide coupling reactions. This porphyrin distortion system provides a powerful tool for manipulating nonplanar porphyrins in MOFs with individual distortion profiles for various advanced applications.

Preparation, characterization, and electrochemical sensing performance of a novel pristine Cd-MOF and its composite with carbon nanotubes.

A novel Cd(II)-organic framework (Cd-MOF) {[Cd(isba)(bbtz)2(H2O)]·H2O}n (1) and its composite with CNTs (Cd-MOF@CNTs), [H2isba = 2-iodo-4-sulfobenzoicacid; bbtz = 1, 4-bis(1,2,4-triazolyl-1-methyl)benzene], were synthesized successfully under ambient conditions. The Cd-MOF is a 2D (4, 4) topological framework, further extending into a two-fold interpenetrated 3D supramolecular network via hydrogen bonding. The activation energy for proton transfer in the composite Cd-MOF@CNT/Nafion membrane is lower than that in pristine Cd-MOF/Nafion, leading to its more temperature-insensitive proton conductivity. Hence, the proton conduction of the composite Cd-MOF@CNT/Nafion membrane was greatly improved. Cyclic voltammograms indicate that the Cd-MOF/GCE only has an oxidation peak with the peak potential suitable for the oxidation of glucose in 0.1 M NaOH. The i-t current response demonstrates that the Cd-MOF/GCE exhibits sensitive and selective oxidative sensing of glucose in the linear range of 0-5 mM with a limit of detection (LOD) of 9.64 µM. Different from the pristine Cd-MOF, Cd-MOF@CNTs shows a pair of irreversible redox peaks with an anodic peak potential appropriate for the glucose oxidation and a cathodic peak potential suitable for the hydrogen peroxide reduction in 0.1 M NaOH. So, the Cd-MOF@CNTs/GCE can be used not only for the electrocatalytic oxidation of glucose, but also for the electrocatalytic reduction of H2O2. The current-time response curve demonstrates that the Cd-MOF@CNTs/GCE exhibits more sensitive and selective oxidative sensing for glucose exponentially in the 0-18.5 mM range with a lower LOD down to 2.63 µM. The reductive sensing of H2O2 increases linearly in the range of 0-14.0 mM (LOD = 33.70 µM). Moreover, the Cd-MOF@CNTs/GCE can detect glucose and H2O2 efficiently in real-world samples. Cd-MOF@CNTs may act as a dual non-enzymatic electrochemical sensory material for glucose and H2O2.

Poly[[bis-(µ-3-amino-5-carb-oxy-benzoato-κ(2)N:O(1))diaqua-zinc] dihydrate].

The Zn(II) atom in the title polymeric compound, {[Zn(C(8)H(6)NO(4))(2)(H(2)O)(2)]·2H(2)O}(n), lies on a center of inversion and is coordinated by two amine N atoms and two carboxyl-ate O atoms from two 3-amino-5-carb-oxy-benzoate anions along with two water mol-ecules in a distorted octa-hedral geometry. The bridging nature of the anion generates a layer motif parallel to (100). Hydrogen bonds of the N-H⋯O and O-H⋯O types exist in the structure. One H atom of the coordinated water mol-ecule and one H atom of the solvent water mol-ecule are each disordered over two positions in a 1:1 ratio.

1-{[4'-(1H-1,2,4-Triazol-2-ium-1-ylmeth-yl)biphenyl-4-yl]meth-yl}-1H-1,2,4-triazol-2-ium bis-(3-carb-oxy-5-iodo-benzoate)-5-iodo-benzene-3,5-dicarb-oxy-lic acid-water (1/2/2).

The neutral carb-oxy-lic acid mol-ecule and the carboxyl-ate anion in the title compound, C(18)H(18)N(6) (2+)·2C(8)H(4)IO(4) (-)·2C(8)H(5)IO(4)·2H(2)O, are both nearly planar (r.m.s. deviations = 0.034 and 0.045 Å, respectively). In the cation, the mid-point of the C-C bond linking the two benzene rings lies on a center of inversion, and the triazole ring is approximately perpendicular to the adjacent benzene ring [dihedral angle = 83.2 (3)°]. In the crystal, the cations, anions, carb-oxy-lic acid and lattice water mol-ecules are linked by N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, generating a ribbon running along [1-10]. The crystal studied was a non-merohedral twin with the components in a 51.2 (1):48.8 (1) ratio.

Poly[[diaqua-(1,10-phenanthroline-κN,N')(µ(3)-4-sulfonato-benzene-1,2-di-car-boxyl-ato-κO:O,O:O)erbium(III)] dihydrate].

The 4-sulfophthalate trianion in the polymeric complex, {[Er(C(8)H(3)O(7)S)(C(12)H(8)N(2))(H(2)O)(2)]·2H(2)O}(n), bridges three water/phenanthroline-coordinated Er(III) ions to form a three-dimensional network architecture. The metal atom is further chelated by a carboxyl-ate group and is covalently bonded to a monodentate carboxyl-ate group as well as to a monodentate sulfonate group in a distorted square anti-prismatic geometry. The coordinating water molecules and the lattice water molecules, one of which is disordered over two positions [major component 65 (3)%], are hydrogen bonded to the network.

Poly[[diaqua-(1,10-phenanthroline-κN,N')(µ(3)-4-sulfonato-benzene-1,2-dicarboxyl-ato-κO:O,O:O)dysprosium(III)] dihydrate].

The 4-sulfophthalate trianion in the polymeric title complex, {[Dy(C(8)H(3)O(7)S)(C(12)H(8)N(2))(H(2)O)(2)]·2H(2)O}(n), bridges three water/phenanthroline-coordinated Dy(III) atoms to form a three-dimensional network architecture. The metal atom is further chelated by a carboxyl-ate group and is covalently bonded to a monodentate carboxyl-ate group and to a monodentate sulfonate group in a distorted square-anti-prismatic geometry. The coordinating and the solvent water mol-ecules are hydrogen bonded to the network. In the crystal, one solvent water mol-ecule is disordered over two positions [major component = 59 (3)%].

(5-Amino-isophthalato-κN)triaqua-(1,10-phenanthroline-κN,N')nickel(II) trihydrate.

The Ni(II) atom in the title compound, [Ni(C(8)H(5)NO(4))(C(12)H(8)N(2))(H(2)O)(3)]·3H(2)O, is six-coordinated in an NiN(3)O(3) octa-hedral geometry. The triply water-coordinated Ni(II) atom is chelated by the phenantroline ligand and is additionally coordinated by the amino group of the 5-amino-isophtalate anion. The anion, the coordinated and the uncoordinated water mol-ecules inter-act through an extensive O-H⋯O and N-H⋯O hydrogen-bonding network, generating a three-dimensional cage-like network.

5-Amino-2,4,6-triiodo-isophthalic acid-4,4'-bipyridine N,N'-dioxide-water (1/1/1).

The aromatic rings of the N,N'-dioxide molecule in the title compound, C(8)H(4)NI(3)O(4)·C(10)H(8)N(2)O(2)·H(2)O, are twisted by 14.0 (2)°. The -CO(2)H substituents of the 5-amino-2,4,6-triiodo-isophthalic acid are twisted by 83.0 (2) and 86.5 (2)° out of the plane of the aromatic ring. In the crystal, the three components are linked by O-H⋯O hydrogen bonds into a three-dimensional network. An N-H⋯O inter-action also occurs. One of the amino H atom is not involved in hydrogen bonding.

2,2'-Biimidazolium 5-amino-2,4,6-tri-bromo-isophthalate.

In the cation of the title salt, C(6)H(8)N(4) (2+)·C(8)H(2)Br(3)NO(4) (2-), the dihedral angle between the two five-membered rings is 2.1 (3)°. In the anion, the mean planes of the carboxyl units are twisted from the benzene ring by 84.3 (4) and 86.2 (3)°. In the crystal, the components are linked by imidazolium-carboxyl-ate N-H⋯O hydrogen bonds, generating a chain running along [10].

(5-Amino-isophthalato-κN)triaqua-(1,10-phenanthroline-κN,N')cobalt(II) trihydrate.

The Co(II) atom in the title compound, [Co(C(8)H(5)NO(4))(C(12)H(8)N(2))(H(2)O)(3)]·3H(2)O, is six-coordinated in a CoN(3)O(3) octa-hedral geometry; the water-coordinated Co(II) atom is chelated by the N-heterocycle. An inter-molecular N-H⋯O hydrogen bond occurs. The carboxyl-ate entity coordinates through the amino group. The carboxyl-ate donor unit, coordinated and uncoordinated water mol-ecules inter-act through O-H⋯O and N-H⋯O hydrogen bonds, generating a tightly-held three-dimensional cage-like network.

Tetra-kis(1H-imidazole-κN)(2-phenyl-propanedioato-κO,O)nickel(II).

In the title complex, [Ni(C(9)H(6)O(4))(C(3)H(4)N(2))(4)], the Ni(II) ion is O,O'-chelated by the phenyl-malonato ligand and coordinated by four imidazole ligands in a slightly distorted octa-hedral geometry. In the crystal structure, symmetry-related mol-ecules are linked by N-H⋯O hydrogen bonds, generating a three-dimensional network.

catena-Poly[[tetra-aqua-[µ(2)-1,4-bis-(1,2,4-triazol-1-yl)butane-κN:N]cadmium(II)] sulfate].

In the polymeric title compound, {[Cd(C(8)H(12)N(6))(H(2)O)(4)]SO(4)}(n), the Cd(II) atom is located on an inversion center and coordinated by four water mol-ecules and two 1,4-bis-(1,2,4-triazol-yl)butane ligands in a distorted CdO(4)N(2) octa-hedral geometry. The 1,4-bis-(1,2,4-triazol-yl)butane ligand is centrosymmetric, the mid-point of the central C-C bond being located on an inversion center. It links adjacent water-coordinated metal atoms into polymeric chains running along the c axis. Adjacent chains are linked by O-H⋯N hydrogen bonds. The S atom of the sulfate anion is located on a twofold rotation axis, thus the sulfate anion is equally disordered over two sites. The sulfate anion links with the polymeric chains via O-H⋯O hydrogen bonds, generating a three-dimensional supra-molecular network.

4-(4-Pyrid-yl)pyridinium 3-amino-5-carb-oxy-2,4,6-triiodo-benzoate-5-amino-2,4,6-triiodo-isophthalic acid (1/1).

In the title ammonium carboxyl-ate-carb-oxy-lic acid co-cystal, C(10)H(9)N(2) (+)·C(8)H(3)I(3)NO(4) (-.)C(8)H(4)I(3)NO(4), the carboxyl-ate anion and carb-oxy-lic acid mol-ecule are linked by O-H⋯O and N-H⋯O hydrogen bonds to form a chain running along the c axis of the monoclinic unit cell. The chains are linked by pyridinum and pyridine N-H⋯O hydrogen bonds, generating a layer motif. O-H⋯N and O-H⋯O hydrogen bonds are also observed.

Diaqua-bis(1,10-phenanthroline-κN,N')zinc(II) 2-hydr-oxy-5-sulfonatobenzoate tetra-hydrate.

The water-coordinated metal centre in the title salt, [Zn(C(12)H(8)N(2))(2)(H(2)O)(2)]C(7)H(4)O(6)S·4H(2)O, is chelated by the two bidentate N-heterocycles, leading to an overall distorted octa-hedral environment. The cation, dianion and solvent water mol-ecules inter-act by O-H⋯O hydrogen bonds to form a layer motif. The SO(3) group is disordered over two positions with respect to the O atoms in a 0.76 (1):0.24 (1) ratio. One of the solvent water molecules is also disordered over two positions in a 0.56 (4):0.44 (4) ratio.

trans,trans,trans-Diaqua-bis(nicotin-amide-κN)bis-(2-nitro-benzoato-κO)copper(II).

The water-coordinated metal atom in the title compound, [Cu(C(7)H(4)NO(4))(2)(C(6)H(6)N(2)O)(2)(H(2)O)(2)], lies on a center of inversion in an all-trans octa-hedral environment with slight distortions. The mol-ecule inter-acts with adjacent mol-ecules through O-H⋯O and N-H⋯O hydrogen bonds, forming a layered network parallel to (010).

catena-Poly[[(2,2'-bipyridine-κN,N')cobalt(II)]-µ-oxalato-κO,O:O,O].

In the title compound, [Co(C(2)O(4))(C(10)H(8)N(2))](n), the oxalate group chelates two adjacent metal atoms, resulting in a zigzag chain running along the a axis. The Co(II) centre exists in an all cis-octa-hedral coordination geometry.

trans,trans,trans-Diaquabis(nicotinamide-κN)bis-(2-nitro-benzoato-κO)cadmium(II) dihydrate.

The cadmium atom in the title compound, [Cd(C(7)H(4)NO(4))(2)(C(6)H(6)N(2)O)(2)(H(2)O)(2)]·2H(2)O, lies on a center of inversion in an all-trans octa-hedral environment. In the crystal, the complex inter-acts with the uncoordinated water mol-ecules through O-H⋯O and N-H⋯O hydrogen bonds, forming a layered network.

Preparation, characterization and luminescence-sensing properties of two ZnII MOFs with mixed 5-amino-2,4,6-tribromoisophthalic acid and bipyridyl-type ligands.

The bromo-substituted aromatic dicarboxylic acid 5-amino-2,4,6-tribromoisophthalic acid (H2ATBIP), in the presence of the N-donor flexible bipyridyl-type ligands 1,3-bis(pyridin-4-yl)propane (bpp) and N,N'-bis(pyridin-4-ylmethyl)oxalamide (4-bpme) and ZnII ions, was used as an O-donor ligand to assemble two novel luminescent metal-organic frameworks (MOFs), namely poly[[(µ-5-amino-2,4,6-tribromoisophthalato-κ2O1:O3)[µ-1,3-bis(pyridin-4-yl)propane-κ2N:N']zinc(II)] dimethylformamide monosolvate], {[Zn(C8H2Br3NO4)(C13H14N2)]·C3H7NO}n, (1), and poly[[(µ-5-amino-2,4,6-tribromoisophthalato-κ2O1:O3)diaqua[µ-N,N'-bis(pyridin-4-ylmethyl)oxalamide-κ2N:N']zinc(II)] monohydrate], {[Zn(C8H2Br3NO4)(C14H14N4O2)(H2O)2]·H2O}n, (2), using the solution evaporation method. Both (1) and (2) were characterized by FT-IR spectroscopy, elemental analysis (EA), solid-state diffuse-reflectance UV-Vis spectroscopy, and powder and single-crystal X-ray diffraction analysis. Complex (1) shows a two-dimensional (2D) corrugated layer simplified as a 2D (4,4) topological network. The supramolecular interactions (π-π stacking, hydrogen bonding and C-Br...Br halogen bonding) play significant roles in the formation of an extended three-dimensional (3D) supramolecular network of (1). Complex (2) crystallizes in the chiral space group P212121 and exhibits a novel 3D homochiral framework, showing a diamond-like topology with Schläfli symbol 66. The homochirality of (2) is further confirmed by the solid-state circular dichroism (CD) spectrum. The second harmonic generation (SHG) property of (2) was also investigated. The hydrogen and C-Br...Br/O halogen bonding further stabilize the framework of (2). The central ZnII ions in (1) and (2) show tetrahedral and octahedral coordination geometries, respectively. The coordinated and uncoordinated water molecules in (2) could be removed selectively upon heating. Most importantly, (1) and (2) show rapid and highly sensitive sensing for a large pool of nitroaromatic explosives (NAEs).

Band gap, sorption properties and fluorescence sensing behaviour of a novel 1D→2D cathenane-like cobalt(II)-organic framework.

A novel hydrolytic stable CoII-organic framework, namely poly[[bis(2-amino-4-sulfonatobenzoato-κO1)tetraaquatris{µ-1,4-bis[(imidazol-1-yl)methyl]benzene-κ2N3:N3'}dicobalt(II)] tetrahydrate], {[Co(C7H5NO5S)(C14H14N4)1.5(H2O)2]·2H2O}n, (1), based on multifunctional 2-amino-5-sulfobenzoic acid (H2asba) and the auxiliary flexible ligand 1,4-bis[(imidazol-1-yl)methyl]benzene (bix), was prepared using the solution evaporation method. The purity of (1) was confirmed by elemental analysis and powder X-ray diffraction (PXRD) analysis. Complex (1) shows a novel 1D→2D interpenetrating network, which is further extended into a 3D supramolecular framework with channels occupied by the lattice water molecules. The 2-amino-4-sulfonatobenzoate (asba2-) ligand adopts a monodentate coordination mode. The bix ligands exhibit gauche-gauche (GG) and trans-trans (TT) conformations. A detailed analysis of the solid-state diffuse-reflectance UV-Vis spectrum reveals that an indirect band gap exists in the complex. The band structure, the total density of states (TDOS) and the partial density of states (PDOS) were calculated using the CASTEP program. The calculated band gap (Eg) matches well with the experimental one. The complex exhibits a reversible dehydration-rehydration behaviour. Interestingly, gas sorption experiments demonstrate that the new fully anhydrous compound obtained by activating complex (1) at 400 K shows selective adsorption of CO2 over N2. Complex (1) retains excellent framework stability in a variety of solvents and manifests distinct solvent-dependent fluorescence properties. Moreover, the complex shows multiresponsive fluorescence sensing for some nitroaromatics in aqueous medium.

A new copper(II) supramolecular coordination polymer and a dinuclear compound with multifunctional 2-amino-5-sulfobenzoic acid and flexible N-donor ligands: synthesis, structure and characterization.

Multifunctional 2-amino-5-sulfobenzoic acid (H2afsb) can exhibit a variety of roles during the construction of supramolecular coordination polymers. The pendant carboxylic acid, sulfonic acid and amino groups could not only play a role in directing bonding but could also have the potential to act as hydrogen-bond donors and acceptors, resulting in extended high-dimensional supramolecular networks. Two new CuII coordination compounds, namely catena-poly[[[diaquacopper(II)]-µ-1,6-bis(1H-1,2,4-triazol-1-yl)hexane-κ2N4:N4'] bis(3-amino-4-carboxybenzenesulfonate) dihydrate], {[Cu(C10H16N6)2(H2O)2](C7H6NO5S)2·2H2O}n or {[Cu(bth)2(H2O)2](Hafsb)2·2H2O}n, (1), and bis(µ-2-amino-5-sulfonatobenzoato-κ2O1:O1')bis{µ-1,2-bis[(1H-imidazol-1-yl)methyl]benzene-κ2N3:N3'}bis[aquacopper(II)] trihydrate, [Cu2(C7H5NO5S)2(C14H14N4)2(H2O)2]·3H2O or [Cu2(afsb)2(obix)2(H2O)2]·3H2O, (2), have been obtained through the assembly between H2afsb and the CuII ion in the presence of the flexible N-donor ligands 1,6-bis(1H-1,2,4-triazol-1-yl)hexane (bth) and 1,2-bis[(1H-1,2,4-triazol-1-yl)methyl]benzene (obix), respectively. Compound (1) consists of a cationic coordination polymeric chain and 3-amino-4-carboxybenzenesulfonate (Hafsb-) anions. Compound (2) exhibits an asymmetric dinuclear structure. There are hydrogen-bonded networks within the lattices of (1) and (2). Interestingly, both (1) and (2) exhibit reversible dehydration-rehydration behaviour.