A three-dimensional gadolinium organic framework based on a pyridinedicarboxylic acid organic linker with a paddle-wheel-type network structure.

A new gadolinium(III)-pyridine-2,5-dicarboxylic acid (GdIII-2,5-H2pdc)-based three-dimensional coordination polymer, namely, poly[dimethylazanium [bis(µ-pyridine-2,5-dicarboxylato)gadolinium(III)]], {[(CH3)2NH2][Gd(C7H3NO4)2]}n, CP-1, has been synthesized via a typical solvothermal method. The as-synthesized material was characterized in the solid state using single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and FT-IR spectroscopy. During the synthesis of CP-1, the in situ dimethylformamide (DMF) promotes the formation of a dimeric unit and these act as secondary building blocks in the assembly of a three-dimensional anionic {[Gd(pdc)2]-}∞ framework. The framework has channels along the c axis which are filled by dimethylazanium cations. Interestingly, the framework shows a helical-type assembly running down the a axis. A Hirshfeld surface analysis of CP-1 suggests that extra stability is provided by hydrogen-bonding interactions. The magnetic properties of CP-1 showed weak antiferromagnetic couplings between adjacent Gd3+ ions.

Synthesis, structure and the Hirshfeld surface analysis of three novel metal-tiron coordination complexes.

Three novel metal-tiron (4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt) and other pillared ligand bpy (4,4'-bipyridyl)-centered coordination polymers of the formulae [Cd(tiron)(bpy)2(H2O)2]·0.5(H2O), 1, [Co3(tiron-bpy)2(bpy)(H2O)8]·(H2O)2, 2, and [Ba2(tiron-bpy)2(H2O)4][solvent], 3, were successfully synthesized under hydrothermal conditions. The as-synthesized materials were well characterized by complimentary techniques such as single-crystal X-ray diffraction, powder X-ray diffraction, Fourier-transform infrared spectroscopy and thermogravimetric analysis techniques. The as-synthesized coordination polymers of 1 and 2 featured 1D chains, while 3 shows a layered structure. Co-based 2 shows linear trinuclear Co(ii) ions and these Co(ii) ions have antiferromagnetic interactions among themselves. The structure of 1 features a zig-zag chain formed by the linkage between monodentate tiron ligands and octahedral Cd(ii) ions, interconnected by a twisted bpy ligand, 2 shows a linear chain constructed from corner-sharing trinuclear octahedral Co(ii) ions and coordinated with a tridentate tiron-bpy adduct ligand, whereas 3 shows nona-coordinated Ba(ii) ions sharing edges with other Ba(ii) ions and connected by hexadentate tiron-bridged structures resulting in a layered structure. In 2 and 3, the bpy nitrogen attacks at the ortho position of the tiron ligand and forms an in situ ligand adduct. The central metal ions show an octahedral geometry in 1 (Cd(ii) ions) and 2 (Co(ii) ions), but nona-coordination of Ba(ii) ions in 3. The short interatomic interactions in the crystal structures were evaluated by mapping the Hirshfeld surface process using pseudo-mirrored 2D fingerprint plots. The major short interatomic interactions H⋯H, O⋯H and C⋯H cover the Hirshfeld surfaces.

Organically templated inorganic-organic hybrid metal (Zn and Cd) Sulfite-oxalates with layered and three-dimensional structures.

We report single crystal X-ray investigations of three d10 metal based oxalate-sulfite inorganic-organic hybrid open framework materials, namely [Zn2(SO3)2(C2O4)0.5(C6N2H13)]·(H2O)2, 1, [C4N2H12]0.5[Zn2(SO3)2(C2O4)0.5(H2O)2], 2 and [C4N2H12][Cd2(SO3)2(C2O4)(H2O)]·H2O, 3 which show layered and three dimensional structures with different organic templates. These materials were synthesized under hydrothermal conditions and characterized by techniques such as single crystal X-ray diffraction, dipole moment calculations, FTIR, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The common feature for 1 and 2 is the interconnection of embedded zinc-sulfite chains via oxalate anions in the framework and in 3, cadmium-oxalate chains are interconnected via sulfite anions. The coordination geometries of metal(ii) ions vary significantly resulting in a ladder-like layered structure in the case of 1, a 3D framework in case of 2 and a layered structure with an embedded one-dimensional channel in 3. The observed structures can also be partly attributed to the influence exerted by the presence of different structure directing agents (SDA) in the lattice. The dipole moments for metal polyhedra 1, 2 and 3 were calculated from bond valence analyses and are 2.39 D for Zn(1)O4N polyhedra and 1.66 D for Zn(2)O4 polyhedra in 1, 24.90 D for Zn(1)O6 and 29.52 D for Zn(2)O4 in 2 and 5.82 D for Cd(1)O7 and 2.90 D for Cd(2)O6 in 3.

Organic-inorganic hybrid three-dimensional metal sulfite-oxalates with honeycomb-like structures.

The crystallographic signatures and characterization of two novel mixed metal hybrid open-frameworks [Na2Mn2(C2O4)(SO3)2(H2O)2] 1 and [NaEu(C2O4)(SO3)(H2O)3] 2 are reported for the first time; they are synthesized under hydrothermal conditions to generate 3D assemblies and honeycomb-like structures. They were further characterized by complementary techniques like PXRD, TGA and DSC. The magnetic properties of 1 show antiferromagnetic interactions between the metal centers and compound 2 shows good photoluminescence properties.

Structural Tuning of Anion-Templated Motifs with External Stimuli through Crystal-to-Crystal Transformation.

Protonation of trans-1,2-bis(4-pyridyl)ethylene (4,4'-bpe) with dilute sulfuric acid (33 %) afforded a protonated adduct [{4,4'-bpe⋅2 H+ }2 {HSO4 }-2 {SO4 }-2 {H2 O}2 ] (1). The neighboring olefinic bond in 1 is in a suitable range (3.931-4.064 Å) to undergo a photochemical [2+2] cycloaddition reaction. Upon irradiation with UV light (365 nm), 1 undergoes a molecular sliding involving the 4,4'-bpe⋅2 H+ units, affording 2, stabilized through OSO4 ⋅⋅⋅π interactions. Heating 1 to 50° C leads to a 3D hydrogen-bonded organic framework (HOF) (3). This process occurs through thermal dissociation of the bisulfate anion. Diffusion of iodine through the crystal lattice of 1 and 3 enables the reduction of sulfate to bisulfate, affording a 1D hydrogen-bonded chain (4). Solid-state 13 C CPMAS NMR, IR, DSC, and powder XRD studies further support stimuli-responsive structural tuning through crystal-to-crystal transformation. All these conversions occur with significant translational and rotational movements along with a series of bond-breaking and bond-forming processes.

The first organically templated open-framework metal-sulfites with layered and three-dimensional diamondoid structures.

The crystallographic signatures and characterization data of two novel organically templated open-framework zinc-sulfites (NH3CH2CH2NH3)[Zn3(SO3)4], 1, and (CN3H6)2[Zn(SO3)2], 2, are reported for the first time, synthesized under hydrothermal conditions using different amines, namely, ethylenediamine and guanidine, to generate 2D (for 1) and 3D (for 2) assemblies with 4-, 6-, 8- and 12-membered rings.