Polybenzobisimidazole‐derived two‐dimensional supramolecular polymer

We report a novel crystalline supramolecular polybenzobisimidazole (SP‐PBBI) capable of providing a two‐dimensional polymer (2DSP‐PBBI) by liquid‐phase exfoliation. A regular arrangement of rigid rod‐like polybenzobisimidazole (PBBI) chains is achieved by interchain hydrogen bonding. Titration of 2DSP‐PBBI with cobalt chloride (CoCl₂) using UV‐Vis spectroscopy demonstrates the presence of bidentate NO ligands on the PBBI backbone and NO–Co(II) complexation. Imaging analysis using atomic force microscopy (AFM) reveals the planar surface morphology of exfoliated 2DSP‐PBBI sheets with lateral dimensions of <1 μm and thickness of <30 nm. The size of the polymer crystal growth is tuned by employing condensation/precipitation polymerization under nonisothermal conditions. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1095–1101     

A square two‐dimensional polymer of cobalt citrate cubanes

The structure of the title complex, poly[dicaesium(I) hexaaquacobalt(II) [octaaquatetra‐μ‐citrato‐hexacobalt(II)] dodecahydrate], {Cs₂[Co(H₂O)₆][Co₆(C₆H₄O₇)₄(H₂O)₈]·12H₂O}_n, at 100 (1) K is formed by layers of a square two‐dimensional polymer composed of Co^II citrate cubanes bridged by magnetically active six‐coordinate Co^II cations. The polymer has plane symmetry p4mm in the c‐axis projection. The cubanes reside on sites of crystallographic symmetry , while the bridging Co^II centres lie on twofold axes. The basic polymeric unit has a charge of 4−, balanced by two Cs⁺ and a [Co(H₂O)₆]²⁺ (symmetry ) cation, which lie in channels between the polymeric layers. Unligated water molecules, of which there are 12 per cubane, enter into an extended intralayer and layer‐bridging hydrogen‐bond pattern, which can be described in detail even though not all of the H atoms of the water molecules were located.     

Strategies in two‐dimensional liquid chromatographic separation of complex polymer systems

Complex synthetic polymer systems as for example copolymers exhibit distributions in at least two of the three basic molecular characteristics which are molar mass, chemical structure/composition and molecular architecture. Size exclusion chromatography (SEC) separates macromolecules according to their size in solution which simultaneously depends on all molecular characteristics. Therefore, multi‐dimensional liquid chromatographic techniques are to be applied to independently assess all different distributions present in the sample. So far, two‐dimensional separations have been attempted. In the first dimension separation column, selected liquid chromatographic mechanisms are intentionally combined to suppress effects of all but one molecular characteristic. Consequently, polymer species are separated exclusively or at least predominantly according to one single parameter. In the second dimension separation column, macromolecules are separated according to another molecular characteristic. In this contribution the methods are briefly reviewed in which effect of polymer molar mass on polymer retention is suppressed. The resulting ”one parameter separation systems” can be on‐line or off‐line connected to another separation system such as SEC to provide more detailed characterization of complex polymers. Besides, selected procedures for the re‐concentration of diluted polymer solutions are concisely treated. These may be utilized for increasing the concentration of sample(s) leaving the first dimension separation column. Eventually, some arrangements for controlled sample re‐introduction into the second dimension separation column are outlined.     

A new two‐dimensional cadmium coordination polymer with 1H‐imidazole‐4‐carboxylate and oxalate

The title compound, poly[aqua(μ₂‐1H‐imidazole‐4‐carboxylato‐κ³N³,O:O′)hemi(μ₂‐oxalato‐κ⁴O¹,O²:O^1′,O^2′)cadmium(II)], [Cd(C₄H₃N₂O₂)(C₂O₄)_0.5(H₂O)]_n, exhibits a two‐dimensional network. The Cd^II cation is coordinated to one N atom and two carboxylate O atoms from two 1H‐imidazole‐4‐carboxylate (Himc) ligands, two carboxylate O atoms from the bridging oxalate anion and one ligated water molecule; these six donor atoms form a distorted octahedral configuration. The oxalate anion lies on a centre of inversion. The Himc ligands connect the Cd^II cations to form –Cd–Himc–Cd–Himc–Cd– zigzag chains, with a Cd...Cd separation of 5.8206 (6) Å along the b direction, which are further linked by tetradentate oxalate anions to generate a two‐dimensional herringbone architecture in the ab plane. These layers are extended to form a three‐dimensional supramolecular framework via O—H...O and N—H...O hydrogen bonds and π–π stacking interactions. The solid‐state photoluminscent behaviour of the title compound has been investigated at room temperature.     

A novel two‐dimensional MnII coordination polymer with 1,2‐bis­(imidazol‐1‐yl)­ethane

In the crystal structure of the title complex, poly­[[di­azido­manganese(II)]‐di‐μ‐1,2‐bis­(imidazol‐1‐yl)­ethane‐κ⁴N³:N^3′], [Mn(N₃)₂(C₈H₁₀N₄)₂]_n or [Mn(N₃)₂(bim)₂]_n, where bim is 1,2‐­bis(imidazol‐1‐yl)­ethane, each Mn^II atom is six‐coordinated in a distorted octahedral coordination environment to four N atoms from four bim ligands and two N atoms from two azide ligands. The Mn^II atoms, which lie on inversion centres, are bridged by four bim ligands to form a two‐dimensional (4,4)‐network. The azide ligands are monodentate (terminal).     

A novel two‐dimensional zinc(II) coordination polymer with 6‐mercaptonicotinic acid

The novel title Zn^II coordination polymer, poly[bis(μ‐6‐thioxo‐1,6‐dihydropyridine‐3‐carboxylato‐κ²S:O)zinc(II)], [Zn(C₆H₄NO₂S)₂]_n, consists of two crystallographically independent zinc centers and two 6‐mercaptonicotinate (Hmna⁻) ligands. Each Zn^II atom is four‐coordinated and lies at the center of a distorted tetrahedral ZnS₂O₂ coordination polyhedron, bridged by four Hmna⁻ ligands to form a two‐dimensional (4,4)‐network. Each Hmna⁻ ion acts as a bridging bidentate ligand, coordinating to two Zn^II atoms through the S atom and a carboxyl O atom. The metal centers reside on twofold rotation axes. The coordination mode of the S atoms and N—H...O hydrogen‐bonding interactions between the protonated N atoms and the uncoordinated carboxyl O atoms give the extended structure a wavelike form.     

A two‐dimensional anionic CdII polymer constructed through dicyanamide coordination bridges

In the search for potential ferroelectric materials, molecular‐based one‐, two‐ and three‐dimensional cadmium(II) organic–inorganic compounds have been of interest as they often display solid–solid phase transitions induced by a variation in temperature. A new cadmium dicyanamide complex, poly[4‐dimethylamino‐1‐ethylpyridin‐1‐ium [tri‐μ‐dicyanamido‐κ⁶N¹:N⁵‐cadmium(II)]], {(C₉H₁₅N₂)[Cd(C₂N₃)₃]}_n, was synthesized by the reaction of 4‐dimethylamino‐1‐ethylpyridin‐1‐ium bromide, cadmium nitrate tetrahydrate and sodium dicyanamide in aqueous solution. In the crystal structure, each Cd^II cation is octahedrally coordinated by six terminal N atoms from six anionic dicyanamide (dca) ligands. Neighbouring Cd^II cations are linked together by dicyanamide bridges to form a two‐dimensional coordination polymer. The organic cations are not involved in the formation of the supramolecular network.     

Nano‐scaled Biomolecular Field‐Effect Transistors: Prototypes and Evaluations

As modern electronics rapidly approach the ultimate level of integration (typically thought to be at the nanoscale level), the fascinating world of biomolecules provides new opportunities and directions for further miniaturization. In this work we review our results in the field of biomolecular electronics, starting from the fabrication of nanojunctions up to the implementation of hybrid devices.     

A two‐dimensional cadmium(II) polymer based on nicotinic acid and thiocyanate ligands

A cadmium–thiocyanate complex, poly[[bis(nicotinic acid‐κN)di‐μ‐thiocyanato‐κ²N:S;κ²S:N‐cadmium(II)] monohydrate], {[Cd(NCS)₂(C₆H₅NO₂)₂]·H₂O}_n, was synthesized by the reaction of nicotinic acid, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, each Cd^II cation is in a distorted octahedral coordination environment, coordinated by the N and S atoms of nicotinic acid and thiocyanate ligands. Neighbouring Cd^II cations are linked together by thiocyanate bridges to form a two‐dimensional network. Hydrogen‐bond interactions between the uncoordinated solvent water molecules and the organic ligands result in the formation of the three‐dimensional supramolecular network.     

Brownian dynamics simulation of two‐dimensional nanosheets under biaxial extensional flow

The morphology dynamics of two‐dimensional nanosheets under extensional flow are investigated using a coarse‐grained model. Nanosheets (graphene, BNNS, MX₂) are promising materials for a variety of materials and electronics applications. Extensional flow fields are often present during dispersion processing, such as spin coating. Both nanosheet properties (e.g., moduli, size) and processing parameters (e.g., extension rate) can have a significant impact on the nanosheet morphology and thus, the structure and properties of the bulk material. Our previously developed dimensionless Brownian dynamics methodology is used to explore biaxial extensional flow. Nanosheets exhibit a flat conformation under extensional flow for high bending moduli and an extended “washrag” conformation for low bending moduli. Intrinsic extensional viscosity increases with strain before reaching a plateau. The intrinsic viscosity exhibits a weak power law with nanosheet molecular weight. These simulation results allow for experimental control over morphology as a function of nanosheet properties and flow type and strength. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1247–1253     

A two‐dimensional copper(II) coordination polymer based on 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid

Single‐crystal X‐ray diffraction analysis of poly[bis(μ₂‐5‐carboxy‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ³N³,O⁴:O⁵)copper(II)], [Cu(C₈H₉N₂O₄)₂)]_n, indicates that one carboxylic acid group of the 2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PDI) ligand is deprotonated. The resulting H₂PDI⁻ anion, acting as a bridge, connects the Cu^II cations to form a two‐dimensional (4,4)‐connected layer. Adjacent layers are further linked through interlayer hydrogen‐bond interactions, resulting in a three‐dimensional supramolecular structure.     

A new two‐dimensional manganese(II) coordination polymer based on thiophene‐3,4‐dicarboxylic acid

A novel manganese coordination polymer, poly[(μ₅‐thiophene‐3,4‐dicarboxylato)manganese(II)], [Mn(C₆H₂O₄S)]_n, was synthesized hydrothermally using 3,4‐thiophenedicarboxylate (3,4‐tdc²⁻) as the organic linker. The asymmetric unit of the complex contains an Mn²⁺ cation and one half of a deprotonated 3,4‐tdc²⁻ anion, both residing on a twofold axis. Each Mn²⁺ centre is six‐coordinated by O atoms of bridging/chelating carboxylate groups from five 3,4‐tdc²⁻ anions, forming a slightly distorted octahedron. The Mn²⁺ centres are bridged by 3,4‐tdc²⁻ anions to give an infinite two‐dimensional layer which incorporates one‐dimensional Mn–O gridlike chains, and in which the 3,4‐tdc²⁻ anion adopts a novel hexadentate chelating and μ₅‐bridging coordination mode. The fully deprotonated 3,4‐tdc²⁻ anion exhibits unexpected efficiency as a ligand towards the Mn²⁺ centres, which it coordinates through all of its carboxylate O atoms to provide the novel coordination mode. The IR spectrum of the complex is also reported.     

A new two‐dimensional anionic cadmium(II) polymer constructed through thiocyanate coordination bridges

A new cadmium–thiocyanate complex, poly[4‐(dimethylamino)pyridin‐1‐ium [di‐μ‐thiocyanato‐κ²N:S;κ²S:N‐thiocyanato‐κN‐cadmium(II)]], {(C₇H₁₁N₂)[Cd(NCS)₃]}_n, was synthesized by the reaction of cadmium thiocyanate and 4‐(dimethylamino)pyridine hydrochloride in aqueous solution. In the crystal structure, each Cd^II ion is square‐pyramidally coordinated by three N and two S atoms from five different thiocyanate ligands, four of which are bridging. The thiocyanate ligands play different roles in the build up of the structure; one role results in the formation of [Cd₂(NCS)₂] building blocks, while the other links the building blocks and cations via N—H...S hydrogen bonds. The N—H...S hydrogen bonds and weak π–π stacking interactions are involved in the formation of both a two‐dimensional network structure and the supramolecular network.     

Theory of relaxation properties of two‐dimensional polymer networks, 1. Normal modes and relaxation times

The local relaxation properties of polymer networks with a two‐dimensional connectivity are considered. We use the mesh‐like network model in which the average positions of junctions form the regular spatial structure consisting of square repeating units (network cells). The two‐dimensional polymer network consisting of “bead and spring” Rouse chains and the simplified coarse‐grained network model describing only the large‐scale collective relaxation of a network are studied. For both dynamic network models the set of relaxation times and the transformation from Cartesian coordinates of network elements to normal modes are obtained. Using the normal mode transformation obtained, in Part 2 of this series the exact analytical expressions for various local dynamic characteristics of the polymer network having a two‐dimensional connectivity will be calculated.     

A new two‐dimensional CdII coordination polymer constructed by pyrazine‐2,3‐dicarboxyl­ate

In the title compound, poly[μ₅‐pyrazine‐2,3‐dicarboxyl­ato‐cadmium(II)], [Cd(C₆H₂N₂O₄)]_n or [Cd(pdc)]_n, where pdc is the pyrazine‐2,3‐dicarboxyl­ate anion, the Cd^II atom is six‐coordinated by five carboxyl­ate O atoms and one N atom from five different pdc ligands in a distorted octa­hedral CdO₅N coordination geometry. Two Cd^II atoms are bridged by carboxyl­ate groups of the pdc ligands to create a dimeric unit. The dimeric units are further connected by the pdc ligands to generate an inter­esting two‐dimensional structure.     

A novel two‐dimensional nickel(II) coordination polymer with 1,4‐bis(1,2,4‐triazol‐1‐ylmethyl)benzene and azide ligands

The coordination geometry of the Ni^II atom in the title complex, poly[diazidobis[μ‐1,4‐bis(1,2,4‐triazol‐1‐ylmethyl)benzene‐κ²N⁴:N^4′]nickel(II)], [Ni(N₃)₂(C₁₂H₁₂N₆)₂]_n, is a distorted octahedron, in which the Ni^II atom lies on an inversion centre and is coordinated by four N atoms from the triazole rings of two symmetry‐related pairs of 1,4‐bis(1,2,4‐triazol‐1‐ylmethyl)benzene (bbtz) ligands and two N atoms from two symmetry‐related monodentate azide ligands. The Ni^II atoms are bridged by four bbtz ligands to form a two‐dimensional (4,4)‐network.     

A stair‐like two‐dimensional silver(I) coordination polymer of N′‐(3‐cyanobenzylidene)nicotinohydrazide

The structure of the title compound, poly[[[μ₃‐N′‐(3‐cyanobenzylidene)nicotinohydrazide]silver(I)] hexafluoroarsenate], {[Ag(C₁₄H₁₀N₄O)](AsF₆)}_n, at 173 K exhibits a novel stair‐like two‐dimensional layer and a three‐dimensional supramolecular framework through C—H...Ag hydrogen bonds. The Ag^I cation is coordinated by three N atoms and one O atom from N′‐(3‐cyanobenzylidene)nicotinohydrazide (L) ligands, resulting in a distorted tetrahedral coordination geometry. The organic ligand acts as a μ₃‐bridging ligand through the pyridyl and carbonitrile N atoms and deviates from planarity in order to adapt to the coordination geometry. Two ligands bridge two Ag^I cations to construct a small 2+2 Ag₂L₂ ring. Four ligands bridge one Ag^I cation from each of four of these small rings to form a large grid. An interesting stair‐like two‐dimensional (3,6)‐net is formed through Ag^I metal centres acting as three‐connection nodes and through L molecules as tri‐linkage spacers.     

A two‐dimensional layered CdII coordination polymer with a three‐dimensional supramolecular architecture incorporating mixed multidentate N‐ and O‐donor ligands

The combination of N‐heterocyclic and multicarboxylate ligands is a good choice for the construction of metal–organic frameworks. In the title coordination polymer, poly[bis{μ₂‐1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole‐κ²N³:N⁴}(μ₄‐butanedioato‐κ⁴O¹:O^1′:O⁴:O^4′)(μ₂‐butanedioato‐κ²O¹:O⁴)dicadmium], [Cd(C₄H₄O₄)(C₉H₈N₆)]_n, each Cd^II ion exhibits an irregular octahedral CdO₄N₂ coordination geometry and is coordinated by four O atoms from three carboxylate groups of three succinate (butanedioate) ligands and two N atoms from two 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole (bimt) ligands. Cd^II ions are connected by two kinds of crystallographically independent succinate ligands to generate a two‐dimensional layered structure with bimt ligands located on each side of the layer. Adjacent layers are further connected by hydrogen bonding, leading to a three‐dimensional supramolecular architecture in the solid state. Thermogravimetric analysis of the title polymer shows that it is stable up to 529 K and then loses weight from 529 to 918 K, corresponding to the decomposition of the bimt ligands and succinate groups. The polymer exhibits a strong fluorescence emission in the solid state at room temperature.     

A novel two‐dimensional cobalt(II) coordination polymer with 1,4‐bis(1,2,4‐triazol‐1‐yl­methyl)­benzene

In the crystal structure of the title complex, poly­[[di­azidocobalt(II)]‐di‐μ‐1,4‐bis(1,2,4‐triazol‐1‐yl­methyl)­benzene‐κ⁴N⁴:N^4′], [Co(N₃)₂(bbtz)₂]_n, where bbtz is 1,4‐bis(1,2,4‐triazol‐1‐yl­methyl)­benzene (C₁₂H₁₂N₆), the Co^II atom, which lies on an inversion centre, is six‐coordinated by four N atoms from four bbtz ligands and by two N atoms from two azide ligands, in a distorted octahedral coordination environment. The Co^II atoms are bridged by four bbtz ligands to form a two‐dimensional [4,4]‐network.     

A two‐dimensional ZnII coordination polymer constructed by benzotriazole‐5‐carboxylate and 1,4,8,9‐tetraazatriphenylene

Poly[[(μ₃‐benzotriazole‐5‐carboxylato‐κ⁴N¹:N³:O,O′)(1,4,8,9‐tetraazatriphenylene‐κ²N⁸,N⁹)zinc(II)] 0.25‐hydrate], {[Zn(C₇H₃N₃O₂)(C₁₄H₈N₄)]·0.25H₂O}_n, exhibits a two‐dimensional layer structure in which the asymmetric unit contains one Zn^II centre, one 1,4,8,9‐tetraazatriphenylene (TATP) ligand, one benzotriazole‐5‐carboxylate (btca) ligand and 0.25 solvent water molecules. Each Zn^II ion is six‐coordinated and surrounded by four N atoms from two different btca ligands and one chelating TATP ligand, and by two O atoms from a third btca ligand, to furnish a distorted octahedral geometry. The infinite connection of the metal ions and ligands forms a two‐dimensional wave‐like (6,3) layer structure. Adjacent layers are connected by C—H...N hydrogen bonds. The solvent water molecules are located in partially occupied sites between parallel pairs of inversion‐related TATP ligands that belong to two separate layers.