Tetrahedral Building Units Research Articles

(NH4)6[Mn3B6P9O36(OH)3]·4H2O: A new open-framework manganese borophosphate synthesized by using boric acid flux method

A new three-dimensional (3-D) open-framework manganese borophosphate, (NH(4))(6)[Mn(3)B(6)P(9)O(36)(OH)(3)]·4H(2)O (denoted as MnBPO-CJ31), has been synthesized by using boric acid flux method. Its anionic framework structure is constructed by the connection of MnO(6) octahedra and BO(4), PO(4) and PO(3)(OH) tetrahedra. It contains 12-ring channels along the [001] direction with a pore diameter of 7.1 Å. It is the first borophosphate featuring a 3-D anionic partial structure with a B/P ratio of 2/3 and an unprecedented fifteen mer tetrahedral fundamental building unit (FBU) [B(6)P(9)O(36)(OH)(3)] exists in this compound. NH(4)(+) ions locate in the void space to balance the negative charge of the inorganic framework. The compound is further characterized by powder XRD, ICP, CHN, TGA and IR analyses. Magnetic study reveals that MnBPO-CJ31 shows interesting canted antiferromagnetic behaviour at low temperature.

Unusual 3D ZnII coordination networks with mixed tetrahedral and square-planar building units: from 2-fold interpenetrating bbf architecture to self-penetrating 86 topological frameworks

Two unusual 4-connected ZnII coordination networks have been successfully constructed from tetrahedral ZnII and square-planar 3,3′,5,5′-azobenzenetetracarboxylate building units with the aid of comparable N-donor bridging spacers [1,3-bis(imidazol)propane and 1,3-bis(imidazol)butane], which direct the distinct 2-fold interpenetrating (64·82)(66)2 (bbf) structure with homochiral double-wall helical tubular motifs and the self-penetrating 86 network, respectively.

Spectroscopic Study of the Effects of Pressure Media on High-Pressure Phase Transitions in Natrolite

Structural phase transitions in natrolite have been investigated as a function of pressure and different hydrostatic media using micro-Raman scattering and synchrotron infrared (IR) spectroscopy. Natrolite undergoes two reversible phase transitions at 0.86 and 1.53 GPa under pure water pressure medium. These phase transitions are characterized by the changes in the vibrational frequencies of four- and eight-membered rings related to the variations in the bridging T-O-T angles and the geometry of the elliptical eight-ring channels under pressure. Concomitant to the changes in the framework vibrational modes, the number of the O-H stretching vibrational modes of natrolite changes as a result of the rearrangements of the hydrogen bonds in the channels caused by a successive increase in the hydration level under hydrostatic pressure. Similar phase transitions were also observed at relatively higher pressures (1.13 and 1.59 GPa) under alcohol-water pressure medium. Furthermore, no phase transition was found up to 2.52 GPa if a lower volume ratio of the alcohol-water to natrolite was employed. This indicates that the water content in the pressure media plays a crucial role in triggering the pressure-induced phase transitions in natrolite. In addition, the average of the mode Grueneisen parameters is calculated to be about 0.6, whilemore » the thermodynamic Grueneisen parameter is found to be 1.33. This might be attributed to the contrast in the rigidity between the TO{sub 4} tetrahedral primary building units and other flexible secondary building units in the natrolite framework upon compression and subsequent water insertion.« less

Three-dimensional iron-series coordination networks based on antiferromagnetic and ferromagnetic dinuclear motifs with mixed carboxylate and aqua bridges

Three coordination polymers of the iron-series transition metal ions with 4-(3-pyridyl)benzoic acid (4,3-Hpybz) ligand were synthesized and structurally and magnetically characterized. They have the formulas [M 2(4,3-pybz) 4(H 2O)] (M = Fe, 1; Co, 2; and Ni, 3). In these isomorphous compounds, octahedrally coordinated metal ions are linked by the mixed ( μ-syn, syn-COO) 2( μ-H 2O) triple bridges to give dinuclear motifs, which serves as tetrahedral building units and are further linked by 4,3-Hpybz to give rise to diamond networks. Magnetic studies demonstrated that the (COO) 2(H 2O) triple bridges induce antiferromagnetic coupling between metal ions in 1 and 2, but compound 3 with the same mixed triple bridges exhibits ferromagnetic coupling, which may be related to orbital countercomplementarity.

Isomorphism between ice and silica

Both ice and silica crystallize into solid-state structures composed of tetrahedral building units that are joined together to form an infinite four-connected net. Mathematical considerations suggest that there is a vast number of such nets and thus potential crystal structures. It is therefore perhaps surprising to discover that, despite the differences in the nature of interatomic interactions in these materials, a fair number of commonly observed ice and silica phases are based on common nets. Here we use computer simulation to investigate the origin of this symmetry between the structures formed for ice and silica and to attempt to understand why it is not complete. We start from a comparison of the dense phases and then move to the relationship between the different open (zeolitic and clathratic) structures formed for both materials. We show that there is a remarkably strong correlation between the energetics of isomorphic silica and water ice structures and that this correlation arises because of the strong link between the total energy of a material and its local geometric features. Finally, we discuss a number of as yet unsynthesized low-energy structures which include a phase of ice based on quartz, a silica based on the structure of ice VI, and an ice clathrate that is isomorphic to the silicate structure nonasil.

Structure of Disodium Dimolybdate Synthesized Using Thermodynamically Stable Molybdenum (VI) Oxide Clusters as Precursors

The structure of disodium dimolybdate (Na2Mo2O7) synthesized by a low‐temperature method in the process of ultrasonic spray pyrolysis using acidified aqueous solutions of thermodynamically stable molybdenum (VI) oxide clusters as a precursor was refined down to an R‐factor of 7%. The refinement of the diffraction data showed that Na2Mo2O7 powder synthesized at 300°C belongs to the base‐centered orthorhombic type of structure with a space group of Cmca (no. 64). It was found that the basic units of the octahedral MoO6 precursor complexes exist in the structure of Na2Mo2O7. Tetrahedral MoO4 building units that coexist together with octahedral units in the structure of Na2Mo2O7 are most likely developed by the termination of weak octahedral bonds and by the placement of the molybdenum atom in the center of the tetrahedra.

Synthesis, Crystal Structure and Properties of Na2MnO2

AbstractNa2MnO2 was prepared via the azide/nitrate route. Stoichiometric mixtures of the precursors (Mn2O3, NaN3 and NaNO3) were heated in an appropriate regime up to 390 °C and annealed at this temperature for 20 h, in specially designed silver containers. As the most prominent feature, the crystal structure of Na2MnO2 (C2/c, Z = 12, a = 12.5026(9), b = 12.1006(9), c = 6.0939(4) Å, β = 117.94(0)°, 1556 independent reflections, R1 = 3.83 % (all data)) forms a three dimensional framework polyanion of corner sharing MnO4‐tetrahedra. The connectivity pattern of the tetrahedral building units corresponds to the moganite structure, a rare SiO2 modification. According to measurements of the magnetic susceptibility in the temperature range from 2 to 750 K, Na2MnO2 shows antiferromagnetic ordering below 250 K. Evaluation of the high temperature data employing the Curie‐Weiss law revealed a magnetic moment of μeff = 5.93 μB, confirming the presence of divalent manganese.

One-, Two-, and Three-Dimensional Coordination Polymers of Stilbenedicarboxylate with Different Metal Ions

Using trans-stilbene-4,4′-dicarboxylic acid (H2STDC) as bridging ligand, we have prepared four new coordination polymers with different transition metal ions, [Cu(STDC)(H2O)(py)2]·2py (1), [Cd(STDC)(py)2]·0.5py (2), [Co(STDC)(py)2]·0.5py (3), and [Ni2(STDC)2(py)4(H2O)]·py·0.5H2O (4), by hydrothermal reactions in the presence of pyridine (py). In compound 1, single metal ions are linked into quasi-linear coordination chains by the organic ligand, and the chains are further assembled into 3D supermolecular architectures through strong O−H (coordinate water)···O (carboxylate) and weak C−H (py)···π (benzene) hydrogen bonds. In compounds 2 and 3, which are isomorphous, binuclear motifs with double carboxylate bridges are linked into two-dimensional (4,4) coordination layers exhibiting 2-fold inclined interpenetration. The last compound exhibits an abnormal 5-fold interpenetration of diamond networks, in which the tetrahedral building unit is defined by a binuclear motif with triple (two carboxylates and a wate...

Reticular Synthesis of Covalent Organic Borosilicate Frameworks

This paper reports the synthesis and characterization of a new crystalline 3D covalent organic framework, COF-202: [C(C6H4)4]3[B3O6 (tBuSi)2]4, formed from condensation of a divergent boronic acid, tetra(4-dihydroxyborylphenyl)methane, and tert-butylsilane triol, tBuSi(OH)3. This framework is constructed through strong covalent bonds (Si-O, B-O) that link triangular and tetrahedral building units to form a structure based on the carbon nitride topology. COF-202 demonstrates high thermal stability, low density, and high porosity with a surface area of 2690 m2 g-1. The design and synthesis of COF-202 expand the type of linkage that could be used to crystallize new materials with extended covalent organic frameworks.

A photoluminescent 8-fold [4 + 4] interpenetrating diamond network formed through strong hydrogen bonds

A new complex with a hydrogen-bonded diamond network, [Zn(2,2′-bipy) 2(HBBDC) 2] ( 1) has been synthesized by the assembly of H 2BBDC, Zn(II) and 2,2′-bipy (H 2BBDC = bibenzyl-4,4′-dicarboxylic acid and 2,2′-bipy = 2,2′-bipyridine). The coordination of two 2,2′-bipy ligands and two carboxylate groups around Zn(II) interplays with the hydrogen-bonding involving the deprotonated and protonated carboxylate, making the mononuclear molecule an unusual supramolecular tetrahedral building unit for the diamond network. The long bridging ligand leads to 8-fold interpenetration of the net in the abnormal [4 + 4] mode. Compound 1 shows a strong fluorescent emission at 400 nm in solid state at room temperature.

Quest for Zeolite-like Metal−Organic Frameworks: On Pyrimidinecarboxylate Bis-Chelating Bridging Ligands

Two novel porous zeolitelike metal-organic frameworks (ZMOFs) were constructed via the single metal ion-based molecular building block approach from rigid and directional tetrahedral building units and pyrimidinecarboxylate bridging ligands; their ion exchange and hydrogen sorption properties were evaluated.

A Ternary Metal−Organic Framework Built on Triangular Organic Spacers, Square and Tetrahedral Co2 Secondary Building Units

A novel metal−organic framework (MOF) of Co12(BTC)8(DMF)6(µ2-H2O)2(µ-H2O)14⊃(solvent) (1⊃(solvents), BTC = 1,3,5-benzenetricarboxylate) prepared by the solvothermal reaction of CoCl2 and H3BTC in dimethylformamide presents another unique and unprecedented ternary MOF in which the triangular organic spacers, square and tetrahedral secondary building units are alternately associated.

A NaCl-like Metal−Organic Framework Constructed by Unprecedented Tetrahedral Cd4O6 and Cd5O6 Units

A solvothermal reaction generated a face-centered cubic cadmium 4,5-imidazoledicarboxylate framework with three-dimensional intersecting channels containing unprecedented tetrahedral Cd4O6 and Cd5O6 building units.

Single-metal-ion-based molecular building blocks (MBBs) approach to the design and synthesis of metal–organic assemblies

The single-metal-ion-based molecular building blocks (MBBs) approach for the construction of metal–organic assemblies, in which hetero-coordinated single metal ions are rendered rigid and directional via nitrogen–oxygen chelation with judiciously selected ligands, has been implemented. Single-metal-ion-based MBBs of the general formula MN x (CO 2) y constitute the building units of metal–organic frameworks (MOFs) and metal–organic polyhedra (MOPs) presented herein. The octahedral MBB, MN 2(CO 2) 4, can occur as two structural isomers depending on the positioning of nitrogen atoms. The MN 2(CO 2) 4 MBBs contain two rings of heterochelation, and depending on the position of the oxygen atoms involved in heterochelation it is possible to generate three different building units (BUs) from the cis-MN 2(CO 2) 4 MBB and two BUs from the trans-MN 2(CO 2) 4 MBB. Assembly of the different BUs derived from the cis-MN 2(CO 2) 4 MBB, through a bifunctional ligand such as 2,5-pyridinedicarboxylic acid, permits the construction of diverse assemblies, such as a metal–organic 2D Kagomé lattice, a discrete octahedron, and a 3D diamondoid-like network. The fac-MN 3(CO 2) 3 MBB mediates a BU with the appropriate geometry to facilitate the formation of a metal–organic cube, and the BU resulting from the mer-MN 3(CO 2) 3 MBB is T-shaped. Tetrahedral building units (TBUs) can be derived either from MN 4(CO 2) 2 or MN 4(CO 2) 4 MBBs, from which zeolite-like MOFs have been constructed. Foremost, rationalization and systemization of such findings offer great potential toward the pursuit of the logical synthesis of functional metal–organic assemblies.

Metal Nuclearity Modulated Four‐, Six‐, and Eight‐Connected Entangled Frameworks Based on Mono‐, Bi‐, and Trimetallic Cores as Nodes

To investigate the relationship between network connectivity and metal nuclearity, we designed and synthesized a series of three-dimensional (3D) entangled coordination frameworks based on different metal cores, namely [Zn(2)(bdc)(2)(L)(2)]2H(2)O (1), [Zn(bdc)(L)(0.5)] (2), [Zn(oba)(L)(0.5)] (3) and [Cd(3)(bdc)(3)(L)(2)(H(2)O)(2)] (4) by self-assembly of d(10) metal salts with the flexible long-chain ligand 1,4-bis(1,2,4-triazol-1-yl)butane (L), and with the rigid and nonrigid aromatic dicarboxylate ligands 1,4-benzenedicarboxylate (bdc) and 4,4'-oxybis(benzoate) (oba). Compound 1 exhibits a threefold interpenetrated diamondoid array typically based on a tetrahedral second building unit (SBU) at a single Zn center. Compound 2 adopts a threefold interpenetrated alpha-polonium-type network that is built from bimetallic cores as six-connected vertices. The structure of 3 also consists of dinuclear units; it comprises a novel (3,4)-connected threefold interpenetrated net with complex (4610)(46(2)10(3)) topology when single zinc centers act as four-connected nodes (or the alpha-Po topology if dinuclear units are considered as six-connected nodes). Compound 4, derived from a crosslinked fivefold interpenetrated diamond-like substructure, is an unusual example of a self-penetrating coordination framework displaying an unprecedented eight-connected 4(20)6(8) topology with trinuclear cadmium clusters as eight-connected nodes which, to our knowledge, not only defines a new topology for eight-connected coordination networks, but also represents the highest connected topology presently known for self-penetrating systems. Detailed structural comparison of these complexes indicates that the increase in metal nuclearity induces the progressive increase in the connectivities of the ultimate nets: that is, the metal nuclearity plays a significant role in tuning the connectivity of a specific network. The thermal and luminescent properties of these compounds are discussed.

Molecular building blocks approach to the assembly of zeolite-like metal–organic frameworks (ZMOFs) with extra-large cavities

Two novel porous anionic zeolite-like metal-organic frameworks, rho-ZMOF and sod-ZMOF, have been synthesized by metal-ligand-directed assembly of rigid and directional tetrahedral building units, InN4 synthesized in situ, and doubly deprotonated bis(bidentate) imidazoledicarboxylic acid ligands (HImDC) in the presence of different structure directing agents (SDAs).

Participation of Sodium in the Bonding of Anionic Networks: Synthesis, Structure, and Bonding of Na3MIn2 (M: Au, Ag).

AbstractFor Abstract see ChemInform Abstract in Full Text.

Participation of Sodium in the Bonding of Anionic Networks: Synthesis, Structure, and Bonding of Na3MIn2 (M = Au, Ag)

Two isostructural compounds Na(3)MIn(2) (M = Au, Ag) with a NiTi(2)-type structure (Fd-3m) were synthesized via typical high-temperature reactions. The anionic M-In structure consists of tetrahedral star building units [In(4)M(4/2)] (TS) that are connected into a three-dimensional framework via shared TS vertexes, with the Na atoms filling the cages. On the basis of TB-LMTO-ASA calculations, the electronic structures of both compounds show substantial participation of sodium in the overall bonding of the structure. Compared with the Ag compound, relativistic effects in the Au phase appear to be significant, as shown in the M-M and M-Na bond length decreases of 0.03-0.04 A.

Solvothermal Synthesis and Structure of the [Ge2Se7]4‐ Anion in (enH2) [{Mn(en)2(enH)}2(μ‐en)] (Ge2Se7)2 and [Mn(dien)2]2Ge2Se7.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Structural and zeolitic features of a series of heterometallic supramolecular porous architectures based on tetrahedral {M(C2O4)4}4– primary building units

The utilization of tetrahedral pre-formed coordination compounds {M(C2O4)4}4- (M = Zr(IV), U(IV); C2O4(2-) = oxalate) permitted the efficient construction of rare examples of heteronuclear supramolecular nano-porous architectures. A series of metal-organic coordination frameworks prepared by association of these building units with either Mn2+, Cd2+, or Mg2+ have been structurally characterized and are described. Their 3-D chemical scaffold is based on the primary tetrahedral building unit but their pore sizes and topologies could be varied through the M2+ metal ion involved in the assembling process, and the anionic tetrahedral moiety. These structures display channels with apertures up to 12 Angstrom x 8 Angstrom which are emptied of solvates at mild temperatures without affecting the chemical scaffold, the integrity of which is maintained up to 250-300 degrees C. A certain degree of flexibility of the coordination polymers upon guest release is suggested by the temperature dependence of the powder X-ray patterns and N2 sorption experiments, but reversible and selective sorption of small molecules has been observed substantiating that these open-frameworks behave like sponges.