Diamond Network Research Articles

Phase Behavior of Nonfrustrated ABC Triblock Copolymers: Weak and Intermediate Segregation

The phase behavior of ABC triblock copolymer melts is studied using weak segregation theory and numerical self-consistent field theory (SCFT). We focus on nonfrustrated systems, with interaction parameters χAB ≃ χBC < χAC. Phase behavior of completely symmetric systems, with χAB = χBC and equal A and C volume fractions, fA = fC, is studied over a range of values of χACN and the ratio k ≡ χAC/χAB, in order to resolve some qualitative differences between the results of previous SCFT studies that were carried out at very different values of k. Studies of full composition triangles are presented for two models with parameters similar to those of poly(isoprene-styrene-ethylene oxide), using values of χijN twice those used in our previous study of the same models. A stable alternating diamond phase, with interpenetrating A and C diamond networks, is found to be stable in symmetric systems in a small region near the ODT. The Fddd (O70) phase of slightly asymmetric ABC triblocks is shown to remain stable well int...

Trace voltammetric detection of serotonin at carbon electrodes: comparison of glassy carbon, boron doped diamond and carbon nanotube network electrodes

The characteristics of three different carbon electrodes, glassy carbon (GC), oxygen-terminated polycrystalline boron-doped diamond (pBDD) and "pristine" carbon nanotube networks (CNTN) as voltammetric sensors for detection of the neurotransmitter serotonin have been investigated. For each electrode, detection sensitivity was determined using cyclic voltammetry (CV), a technique often used to provide information on chemical identity in electrochemical assays. The CNTN electrodes were found to exhibit background current densities ca. two orders of magnitude smaller than the GC electrode and ca. twenty times smaller than pBDD, as a consequence of their "pristine" low capacitance and low surface coverage. This was a major factor in determining serotonin detection limits from CV, of 10 nM for the CNTN electrode, 500 nM for pBDD and 2 microM for GC. The two most sensitive electrodes (CNTN and pBDD) were further investigated in terms of resistance to electrode fouling. CV analysis showed that fouling was less on the pBDD electrode compared to the CNTN and, furthermore, for the case of pBDD could be significantly minimised by careful selection of the CV potential limits, in particular by scanning the electrode potential to suitably cathodic values after oxidation of the serotonin.

Tuning of unusual secondary ligands to construct fluorescent zinc coordination polymers of an unsymmetrical pyridylbenzoate ligand from 1D chain to interdigital or porous 2D layers and interpenetrated 3D frameworks

Four dicarboxylic acids and nitrilotriacetic acid as secondary ligands have been used to tune the zinc(II)-organic frameworks constructed by an unsymmetrical pyridylbenzoate ligand, 3-pyrid-4-ylbenzoic acid (HL1). Interestingly, malonic acid (H2L2), nitrilotriacetic acid (H3L3), and succinic acid (H2L4), not coordinating to the metal centers and not even existing in the resultant coordination polymers can, however, tune the coordinating modes of L1 and zinc ions, and then the frameworks of their coordination polymers from interdigital 2D layers of [Zn5(L1)10(H2O)3.5]n (1), to porous 2D distorted square grids of [Zn(L1)2(H2O)1.5]n (2), and 4-fold interpenetrated 3D diamond networks of [Zn(L1)2]n (3), respectively. Especially, the topology of 1 displays an unprecedented (3,4)-connected 2D trilayer net with the Schlafli symbol of (62.8)2(6.84.10). For 2, there are 0.7 × 0.8 nm2 1D channels hosting water molecules. Besides, pimelic acids (H2L5) act as bridges for zinc dimeric constructing units and terminers for the 1D chain constructed by dimeric nodes and antiparallel double L1 spacers for [Zn2(L1)2(L5)]n (4). By contrast, terephthalic acids (H2L6) acting as bridges link similar 1D chains in 4 to construct interdigital 2D layers for [Zn2(L1)2(L6)]n (5). Finally, these five coordination polymers all exhibit strong fluorescent emissions at room temperature and high thermal stabilities.

Mn(II)-Binaphthalenyl Dicarboxylate Complexes: Helical Rectangular Tubes, (4,4) Grid Chiral Layer and Three-Dimensional Cubic Diamond Frameworks

Reactions of 2,2′-dihydroxyl-[1,1′]-binaphthalene-3,3′-dicarboxylate acid (H2bna) with manganese chloride by a solvent or solvothermal method in the presence of pyridine (py) or 4-picoline (pic) give birth to three 1D to 3D frameworks: [Mn(bna)(DMF)2(H2O)2]n·nDMF (1), {(Hpic)2[Mn3(bna)4(C2H5OH)2(H2O)2]·5H2O}n (2), and {(Hpy)2[Mn3(bna)4(py)2(H2O)2]·4H2O}n (3) (DMF = N,N′-dimethylformamide). Crystal structure analyses reveal that 1 is a mesomer with equivalent R- and L-helical rectangular tubes constructed from homochiral ligands, which is further assembled into a 3D supramolecular network through hydrogen bonds and C−H···π interactions. Complex 2 consists of a (4,4) grid chiral layer structure, while 3 features a 3D cubic diamond network with Schlafli symbol 66 topology, though they both comprise of [Mn3(μ2-COO)6(COO)2] pinwheel molecular building blocks which act as 4-connected nodes and bna2− as linkers. Magnetic studies indicate that antiferromagnetic couplings exist in both 2 and 3.

Magnetic and Electrical Properties of Single-Crystalline Mn-Doped Ge Nanowires

We report on synthesis of Mn-doped Ge nanowires and their magnetic and electrical properties. The nanowires were grown on the silicon substrate by vapor−liquid−solid mechanism using Au as catalyst and GeCl4 and MnCl2 as precursor. Anomalous X-ray scattering measurement makes it clear that Mn atoms are substitutionally incorporated with the diamond network of host Ge sites. Superconducting quantum interference device characterization indicated that the nanowires possess ferromagnetism up to room temperature. X-ray magnetic circular dichroism spectra at Mn L2,3-edges showed that doped Mn has local spin moment with the 3d5 electronic configuration above room temperature, meaning that the ferromagnetism originates from doped Mn2+ ions. Electrical characterization of a nanowire field effect transistor revealed the improved p-type behavior with hole mobility of 4.95 cm2/V·s.

Hydrothermal Synthesis, Structures, and Properties of Manganese(II) and Zinc(II) Coordination Polymers with Different Phenylenediacrylates

Four novel metal−organic coordination polymers, [Zn2(ppda)(phen)2(HCOO)2] (1), [Mn(ppda)(phen)(H2O)2]·DMF (2), [Zn(mpda)(phen)]·1.5H2O (3), and [Mn2(mpda)2(phen)2] (4), (H2ppda = p-phenylenediacrylic acid, H2mpda = m-phenylenediacrylic acid, and phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions. Compound 1 consists of two-dimensional (2D) bilayers in which formate-bridged chains are cross-linked by ppda ligands, and the bilayers are sustained by infinite zipper-like π−π stacking of the phen ligands. Compounds 2 and 3 are both one-dimensional (1D) coordination polymers, but exhibit different chain shapes due to the different geometry of ppda and mpda. Via O−H···O hydrogen bonding and pairwise phen···phen π−π stacking, the zigzag chains in 2 are assembled into a three-dimensional (3D) diamond network with 3-fold interpenetration, while the helical chains in 3 are packed into a 3D structure through quadruple π−π stacking arrays. Compound 4 is composed of double twist chains of b...

Complex Crystal Structures Formed by the Self-Assembly of Ditethered Nanospheres

We report the results from a computational study of the self-assembly of amphiphilic ditethered nanospheres using molecular simulation. As a function of the interaction strength and directionality of the tether-tether interactions, we predict the formation of four highly ordered phases not previously reported for nanoparticle systems. We find a double diamond structure comprised of a zinc blende (binary diamond) arrangement of spherical micelles with a complementary diamond network of nanoparticles (ZnS/D), a phase of alternating spherical micelles in a NaCl structure with a complementary simple cubic network of nanoparticles to form an overall crystal structure identical to that of AlCu2Mn (NaCl/SC), an alternating tetragonal ordered cylinder phase with a tetragonal mesh of nanoparticles described by the [8,8,4] Archimedean tiling (TC/T), and an alternating diamond phase in which both diamond networks are formed by the tethers (AD) within a nanoparticle matrix. We compare these structures with those observed in linear and star triblock copolymer systems.

Dicarboxylate anion-dependent assembly of Ni(II) coordination polymers with 4,4′-dipyridyl sulfide

Four new coordination polymers, [Ni(isop)(bps)(H2O)]2n·5H2O (1), [Ni(O2N–BDC)(bps)(H2O)]2n (2), [Ni(OH–BDC)(bps)2(H2O)]n (3) and {[Ni2(H2O)(tbip)2(bps)2]}n (4) (bps = 4,4′-dipyridyl sulfide, H2isop= isophthalic acid, O2N–BDC = 5-nitroisophthalic acid, OH–BDC = 5-hydroxyisophthalic acid, H2tbip = 5-tert-butyl isophthalic acid), have been isolated from parallel hydrothermal reactions of Ni(OAc)2·4H2O and bps with isop, O2N–BDC, OH–BDC and H2tbip, respectively. Compound 1 is an unusual 2D double layered supramolecular motif generated by hydrogen bonding interactions of two single 2D (4,4) networks. Compound 2 has a highly puckered 2D (4,4) sheet and further stack viaO⋯O intermolecular contacts to form a 3D supramolecular structure. Compound 3 features a 2D rectangular grid layer with terminal bps ligands projecting into the interlayer space, leading to a highly interdigitated packing motif and further expansion to generate a 3-D network through interlayer C–H⋯π stacking interactions. Compound 4 contains [Ni2(H2O)]4+ dimers bridged by pairs of ligands into a single 3D diamond network with alternately left-handed and right-handed helical channels. As compared to isop, the coexistence of electron-donating (–OH, –C(CH3)3) or electron-withdrawing (–NO2) groups in the dicarboxylate derivatives has a significant effect on the molecular self-assembly. Variable-temperature magnetic susceptibility measurements reveals the existence of weak ferromagnetic interactions between the nickel centers in 4.

Four-, and six-connected entangled frameworks based on flexible bis(imidazole) ligands and long dicarboxylate anions

A series of four- and six-connected entangled structures, namely [Cd(oba)(bbi)]·0.5H2O (1), [Ni(oba)(bbi)]2·H2O (2), [Co(bpea)(bbi)]·H2O (3), [Co2(bpea)2(bbi)2]·1.5H2O (4), [Cd(oba)(1,4-bix)] (5), and [Ni2(oba)2(1,4-bix)(H2O)2] (6), where oba = 4,4′-oxybis(benzoate), bpea = biphenylethene-4,4′-dicarboxylate, 1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene, and bbi = 1,1′-(1,4-butanediyl)bis(imidazole), have been successfully synthesized through a hydrothermal process. The structures of 1 and 2 both consist of two interpenetrating CdSO4 nets. In 1, the two nets are related by symmetry. By comparison, the individual nets are, unusually, crystallographically distinct in 2. The structures of 3 and 4 both contain interpenetrating diamond networks. In 3, there are 6 interpenetrating nets, and they show the usual mode of interpenetration. For 4, however, there are 7 nets, and a rare ‘abnormal’ [4 + 3] interpenetration mode is observed. In 5, the oba and 1,4-bix ligands linked the Cd(II) atoms into a deeply corrugated 2D sheet. The corrugated 2D sheets polycatenate each other in a parallel manner with DOC (degree of catenation) = 2, yielding a rare 2D → 3D parallel polycatenation net. In 6, the dinuclear Ni(II) units are bridged by the oba ligands to generate a 2D (4,4) square-grid with a rhombic window. It is interesting that the two identical (4,4) square-grids show 2D → 2D parallel interpenetration but are then further crosslinked by the 1,4-bix ligands to yield an unusual 3D self-penetrating net with an unique 6-connected 44.611 topology. The importance of bbi conformations and metal sources in the framework formation of complexes 1–6 was unraveled. Their infrared spectra, powder X-ray diffraction (XRD) and photoluminescent properties were also investigated in detail.

Structural diversity and properties of ZnII and CdII complexes with a flexible dicarboxylate building block 1,3-phenylenediacetate and various heterocyclic co-ligands

A series of Zn(II) and Cd(II) complexes with a flexible dicarboxylate building block and various heterocyclic co-ligands, formulated as {[Zn(2)(pda)(2)(phen)(2)].2H(2)O}(n) (1), {[Zn(pda)(dpe)].H(2)O}(n) (2), [Zn(pda)(bpp)](n) (3), {[Cd(2)(pda)(2)(2,2'-bipy)(2)].2H(2)O}(n) (4), {[Cd(pda)(4,4'-bipy)(H(2)O)].H(2)O}(n) (5) and {[Cd(2)(pda)(2)(bpp)(3)].14H(2)O}(n) (6) (pda = 1,3-phenylenediacetate, phen = 1,10-phenanthroline, dpe = 1,2-di(4-pyridyl)ethylene, bpp = 1,3-bi(4-pyridyl)propane, 2,2'-bipy = 2,2'-bipyridine, and 4,4'-bipy = 4,4'-bipyridine), have been synthesized and structurally characterized. In 1, the (H(2)O)(8) clusters interlink the cyclic coordination dimers to give a 3D network through hydrogen bonding. Both 2 and 3 feature 2D corrugated (4,4) layers, which are of 2-fold interpenetrating for 3. In 4, the dimeric Cd(II) subunits are connected by the 1,3-pda ligands to generate a rampart-shaped 1D chain motif. As for 5, the [Cd(pda)](2) rings are connected by the paired 4,4'-bipy ligands to afford a tube-shaped 1D motif. In contrast to 1-5, complex displays a 3D diamond network and, interestingly, the T5(0)A(0)A(2) water tapes are found to locate in the channels of this 3-D array. A structural comparison of these complexes demonstrates that the characteristics of auxiliary ligands (from chelating to bridging) play a key role in governing the coordination motifs as well as the 3-D supramolecular lattices. Solid-state properties such as photoluminescence and thermal stability of 1-6 have also been studied.

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...

Host-country environment and subsidiary competence: Extending the diamond network model

We extend the “centers of excellence” concept to address the diversity and multidimensionality of subsidiary competence. Using Rugman and Verbeke's diamond network model, we hypothesize the contingencies influencing the links between host-country environments and subsidiary competence configuration, and provide evidence from more than 2000 subsidiaries in seven European countries. Our results provide new insights into how multinational enterprises can overcome “unbalanced” national diamonds by acquiring complementary capabilities across borders.

The Designed Assembly of Augmented Diamond Networks From Predetermined Pentanuclear Tetrahedral Units

The Designed Assembly of Augmented Diamond Networks From Predetermined Pentanuclear Tetrahedral Units

The Designed Assembly of Augmented Diamond Networks From Predetermined Pentanuclear Tetrahedral Units

The Designed Assembly of Augmented Diamond Networks From Predetermined Pentanuclear Tetrahedral Units

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.

D10-Metal coordination polymers based on analogue di(pyridyl)imidazole derivatives and 4,4′-oxydibenzoic acid: influence of flexible and angular characters of neutral ligands on structural diversity

A series of mixed-ligand coordination complexes, namely [Zn(L(1))(oba)] (), [Cd(L(1))(oba)] (), [Zn(2)(L(2))(oba)(2)].8H(2)O (), [Cd(2)(L(2))(oba)(2)].2H(2)O (), [Zn(3)(L(3))(oba)(3)] (), [Cd(2)(L(3))(oba)(2)].(L(3)) (), [Cd(L(4))(oba)].H(2)O () and [Cd(L(5))(oba)].3H(2)O (), where L(1) = 2-(2-pyridyl)imidazole, L(2) = 1,4-bis[2-(2-pyridyl)imidazol-1-yl]butane, L(3) = 1,4-bis[2-(2-pyridyl)imidazol-1-ylmethyl]benzene, L(4) = 1,3-bis[2-(2-pyridyl)imidazol-1-ylmethyl]benzene, L(5) = 1,2-bis[2-(2-pyridyl)imidazol-1-ylmethyl]benzene and H(2)oba = 4,4'-oxydibenzoic acid, have been synthesized under hydrothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. In compounds and , oba(2-), L(1) ligand and Zn(II) or Cd(II) ions assemble to form the parallel chains or parallel sheets which are linked by the weak hydrogen bonding and pipi stacking interactions to give the 2D supramolecular sheet or 3D supramolecular net, respectively. For , L(2) ligands connect [Zn(oba)] chains to generate a unusual (10,3)-b topological structure which is the first example for eight-fold interpenetrating framework based on the (10,3)-b net. In , L(2) ligands link [Cd(oba)] double-chains to give a 2D sheet which is assembled by pipi stacking interactions to obtain a 3D supramolecular net. In , L(3) ligands link Zn(II) ions from alpha-Po net formed by Zn(II) ions and oba(2-) anions to show a novel 3D 8-connected self-penetrating framework with the unreported (4(16).6(11).8) topological structure. In , the double-chains constructed by Cd(II) and oba(2-) anions are linked by one kind of L(3) ligand to form a layer-like structure which is assembled by pipi stacking interactions to show a 3D supramolecular structure. In , oba(2-) anions coordinate to Cd(II) cations to form chains which are connected by L(4) to form a four-fold interpenetrating diamond network. In , the weak hydrogen bonding and pipi stacking interactions connect the [Cd(L(5))(oba)] chains to give a 2D supramolecular sheet. By careful inspections of the structures of , we believe that the different flexible and angular neutral ligands, coordination geometries of metal centers and weak interactions (hydrogen bonds and pipi stacking interactions) are crucial factors for the formation of the different structures. The photoluminescent properties of have been studied in the solid state at room temperature.

Syntheses, structures and luminescence properties of cadmium(II) coordination polymers with in situ formed oxalate and bis(chelating) bridging ligands

Hydrothermal reactions of 2-cyanopyrimidine and CdCl2 in the absence and presence of sodium azide yielded two coordination polymers, [Cd3(ox)2(pymc)2]·2H2O (1) and [Cd2(pymtz)2(ox)]·H2O (2), respectively, where pymc = 2-pyrimidinecarboxylate, pymtz = 5-(2′-pyrimidyl)tetrazolate and ox = oxalate. All the ligands in these compounds were generated in situ by the hydrolysis of 2-cyanopyrimidine (pymCN) or the [2 + 3] cycloaddition of the azide ion to the nitrile. In compound 1, seven-coordinated Cd ions are linked by oxalate bridges into a diamond network based on Cd2O2 nodes, and eight-coordinated Cd ions are linked to the network through pymc and oxalate bridges. In compound 2, seven-coordinated Cd ions are bridged by oxalate ions into 1D Cd2(ox) ribbons, which are further linked by bis(chelating) pymtz to give a 3D framework that exhibits the 5-connected 4466 net topology based on Cd2O2 nodes. The compounds exhibit intense luminescence in the solid state.

Isophthalic acid–3,6-bis(2-pyrazinyl)-1,4-dihydro-1,2,4,5-tetrazine (1/1)

The cocrystallization of isophthalic acid (H2ip) with 3,6-bis­(2-pyrazin­yl)-1,4-dihydro-1,2,4,5-tetra­zine (H2bpztz) yields the title binary mol­ecular cocrystal, C8H6O4·C10H8N8 or [(H2ip)·(H2bpztz)]. In the isophthalic acid molecule, a crystallographic twofold rotation axis passes between the carboxyl substituents. In the tricyclic molecule, a crystallographic twofold rotation axis is perpendicular to the central ring. Inter­molecular O—H⋯N and C—H⋯O inter­actions between the carboxyl and pyrazinyl groups of the two components produces a one-dimensional zigzag tape. Further N—H⋯N hydrogen bonds between adjacent H2bpztz mol­ecules generate a three-dimensional supra­molecular network. The resulting diamond networks are of fivefold parallel inter­penetration and are consolidated by π–π stacking inter­actions (3.70 Å) between the aromatic rings.

A Group Construction Method with Applications to Deriving Pruned Interconnection Networks

A number of low degree and, thus, low complexity, Cayley-graph interconnection structures, such as honeycomb and diamond networks, are known to be derivable by systematic pruning of 2D or 3D tori. In this paper, we extend these known pruning schemes via a general algebraic construction based on commutative groups. We show that, under certain conditions, Cayley graphs based on the constructed groups are pruned networks when Cayley graphs of the original commutative groups are kD tori. Thus, our results offer a general mathematical framework for synthesizing and exploring pruned interconnection networks that offer lower node degrees and, thus, smaller VLSI layout and simpler physical packaging. Our constructions also lead to new insights, as well as new concrete results, for previously known interconnection schemes such as honeycomb and diamond networks

Defect creation in diamond by hydrogen plasma treatment at room temperature

The defect creation mechanism of diamond by hydrogen plasma treatment at room temperature was investigated. Electron spin resonance (ESR) observation revealed that hydrogen plasma treatment at room temperature gave rise to a highly defective structure. In contrast, very few defects were created in silicon. The difference of the defect creation mechanism between diamond and Si was discussed on the basis of the existence of sp 2 hybridization in diamond network.