Copper Selective Polymeric Extractant Synthesized by Ring-Opening Metathesis Polymerization.

Novel polymers bearing pendant picolinic acid functionalities have been synthesized by ring-opening metathesis polymerization (ROMP) for applications in separations-based purification protocols. These polymers and their corresponding monomer were shown to be selective for Cu2+ over a variety of other divalent metal cations as inferred from pH dependent studies carried out under both liquid-liquid and solid-liquid extraction conditions. The polymer system of this study also showed high selectivity for Cu2+ over Ni2+ in mock protocols that could be relevant to the purification of Cu radioisotopes. Separation factors as high as 290 were achieved for extractions from solutions containing a 100-fold excess of Ni2+ relative to Cu2+.

Electronic Interactions of n-Doped Perylene Diimide Groups Appended to Polynorbornene Chains: Implications for Electron Transport in Organic Electronics.

A polymer consisting of a polynorbornene backbone with perylene diimide (PDI) pendant groups on each monomeric unit is synthesized via ring opening metathesis polymerization. The PDI pendant groups along the polymer backbone, studied by UV-vis absorption, fluorescence emission, and electron paramagnetic resonance spectroscopy in addition to electrochemical methods, show evidence of molecular aggregation and corresponding electronic coupling with neighboring groups, which forms pathways for efficient electron transport from one group to another in a specific reduced form. When n-doped, the title polymer shows redox conductivity of 5.4 × 10-3 S cm-1 , comparable with crystalline PDI materials, and is therefore a promising material for use in organic electronics.

Discerning the Impact of a Lithium Salt Additive in Thin-Film Light-Emitting Electrochemical Cells with Electrochemical Impedance Spectroscopy.

Light-emitting electrochemical cells (LEECs) from small molecules, such as iridium complexes, have great potential as low-cost emissive devices. In these devices, ions rearrange during operation to facilitate carrier injection, bringing about efficient operation from simple, single-layer devices. Prior work has shown that the luminance, efficiency, and responsiveness of iridium LEECs is greatly enhanced by the inclusion of small fractions of lithium salts, but much remains to be understood about the origin of this enhancement. Recent work with planar devices demonstrates that lithium additives in iridium LEECs enhance double-layer formation. However, the quantitative influence of lithium salts on the underlying physics of conventional thin-film, sandwich structure LEECs, which beneficially operate at low voltages and generate higher luminance, has yet to be clarified. Here, we use electrochemical impedance spectroscopy to discern the impact of the lithium salt concentration on double-layer formation within the device and draw correlations with performance metrics, such as current, luminance, and external quantum efficiency.

Electrochemical modification of indium tin oxide using di(4-nitrophenyl) iodonium tetrafluoroborate.

Optoelectronic applications often rely on indium tin oxide (ITO) as a transparent electrode material. Improvements in the performance of such devices as photovoltaics and light-emitting diodes often requires robust, controllable modification of the ITO surface to enhance interfacial charge transfer properties. In this work, modifier films were deposited onto ITO by the electrochemical reduction of di(4-nitrophenyl) iodonium tetrafluoroborate (DNP), allowing for control over surface functionalization. The surface coverage could be tuned from submonolayer to multilayer coverage by either varying the DNP concentration or the number of cyclic voltammetry (CV) grafting scans. Modification of ITO with 0.8 mM DNP resulted in near-monolayer surface coverage (4.95 × 10(14) molecules/cm(2)). X-ray photoelectron spectroscopy (XPS) analysis confirmed the presence of 4-nitrophenyl (NO2Ph) moieties on the ITO surface through the detection of a NO2 nitrogen signal at 405.6 eV after grafting. Further XPS evidence suggests that the NO2Ph radicals do not bond to the surface indium or tin sites, consistent with modification occurring either through bonding to surface hydroxyl groups or through strong physisorption on ITO. CV in the presence of an electroactive probe and electrochemical impedance spectroscopy (EIS) were used to investigate the electronic effects that modification via DNP has on ITO. Even at submonolayer coverage, the insulating organic films can reduce the current response to ferrocene oxidation and reduction by more than 25% and increase the charge transfer resistance by a factor of 10.

Incorporation of thieno[3,2-b]thiophene moieties as novel electropolymerizable groups in a conducting metallopolymer and study of the effect on photostability.

A novel nickel(II)-containing conducting metallopolymer utilizing thieno[3,2-b]thiophene moieties as the electropolymerizable groups is synthesized and characterized. A metal-free polymer is also obtained via electropolymerization of the title ligand allowing comparative studies of the electrochemical and spectroscopic properties of the polymer system in the presence and absence of nickel(II) metal ions. Photodegradation of the two polymers is studied along with an analogous system incorporating bithiophene as the electropolymerizable groups. Stability is found to be comparable between the metal-free thieno[3,2-b]thiophene- and bithio-phene-based polymers; however, significant enhancement is observed in the thieno[3,2-b]thiophene-based nickel(II) conducting metallopolymer.

6-Bromo-N-(6-bromo-pyridin-2-yl)-N-[4-(2,3-di-hydro-thieno[3,4-b][1,4]dioxin-5-yl)phen-yl]pyridin-2-amine.

In the title mol-ecule, C22H15Br2N3O2S, the central benzene ring forms dihedral angles of 12.39 (17), 56.66 (17) and 74.71 (19)°, respectively, with the mean planes of the thio-phene and two pyridine rings. The dioxane ring is in a half-chair conformation. An intra-molecular C-H⋯O hydrogen forms an S(6) ring. The amine N atom is sp (2)-hybridized.

4-(2,3-Di-hydro-thieno[3,4-b][1,4]dioxin-5-yl)aniline.

In the title mol-ecule, C12H11NO2S, the dioxane-type ring adopts a half-chair conformation. The thio-phene ring forms a dihedral angle of 12.53 (6)° with the benzene ring. In the crystal, N-H⋯O, hydrogen bonds link mol-ecules, forming chains along the c-axis direction. A weak intra-molecular C-H⋯O hydrogen bond is observed.

(E)-4-[7-(2,3-Di-hydro-thieno[3,4-b][1,4]dioxin-5-yl)-2,1,3-benzo-thia-diazol-4-yl]-2-[(neo-pentyl-imino)-meth-yl]phenol.

In the title mol-ecule, C24H23N3O3S2, the benzo-thia-diazole ring system is essentially planar, with an r.m.s. deviation of 0.020 (8) Å. The thio-phene and hy-droxy-substitiuted rings form dihedral angles of 23.43 (9) and 35.45 (9)°, respectively, with the benzo-thia-diazole ring system. An intra-molecular O-H⋯N hydrogen bond is observed. In the crystal, weak C-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distance = 3.880 (3) Å] link mol-ecules into chains along [100]. In addition, there are short S⋯S contacts [3.532 (3) Å] which link these chains, forming a two-dimensional network parallel to (010).

5-Phenyl-1,2,5-di-thia-zepane.

In the title compound, C10H13NS2, the seven-membered ring adopts a chair conformation. The S-S bond length is 2.0406 (5) Šand the C-S-S-C torsion angle is -83.89 (7)°. The amine group is sp (2)-hybridized. In the crystal, mol-ecules are linked into chains along [001] by weak inter-molecular S⋯S contacts of 3.5246 (5) Å.

Anion-dependent self-assembly of near-infrared luminescent 24- and 32-metal Cd-Ln complexes with drum-like architectures.

Two series of 4d-4f clusters [Ln8Cd24L12(OAc)48] and [Ln6Cd18L9Cl8(10)(OAc)28(26)] (Ln = Nd, Gd, Er, and Yb) with novel drum-like structures were prepared using a flexible Schiff base ligand. Their NIR luminescence properties were determined.

A comparison of 3,4,6a,7,10,10a-hexahydro-7,10-epoxypyrimido[2,1-a]isoindol-6(2H)-one and 2-(2-aminoethyl)-3a,4,7,7a-tetrahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione: structural and reactivity differences of two homologous tricyclic imides.

The crystal structures of 3,4,6a,7,10,10a-hexahydro-7,10-epoxypyrimido[2,1-a]isoindol-6(2H)-one, C11H12N2O2, and 2-(2-aminoethyl)-3a,4,7,7a-tetrahydro-1H-4,7-epoxyisoindole-1,3(2H)-dione, C10H12N2O3, two tricyclic imides, show one and two molecules in the asymmetric unit, respectively. Intermolecular hydrogen-bonding interactions are observed in both compounds.

Conducting metallopolymers as precursors to fabricate palladium nanoparticle/polymer hybrids for oxygen reduction.

The novel conducting metallopolymer [N,N'-((2,2'-dimethyl)propyl)bis(5-(2,2'-bithiophene-5-yl)salcylideniminato-palladium(II)](n) prepared by electropolymerization provides a polymer matrix in which the palladium metal centers are evenly distributed. The metal centers embedded directly in the conducting metallopolymer backbone serve as seed points for size-controlled palladium nanoparticle (NP) growth of 3.8 to 4.9 nm NPs within the conducting metallopolymer film. The palladium NP/conducting metallopolymer hybrid material has demonstrated electrocatalytic behavior toward oxygen reduction with peak current densities around 400 µA/cm(2) in acidic aqueous conditions. These results demonstrate a promising new method for the production of electrocatalytically active hybrid materials.

1,1',1''-{[4-(3,4-Ethyl-ene-dioxy-thio-phen-2-yl)phen-yl]methane-tri-yl}tris-(1H-pyra-zole).

In the title complex, C(22)H(18)N(6)O(2)S, two of the pyrazole rings are disordered over two sets of sites with ratios of refined occupancies of 0.58 (2):0.42 (2) and 0.517 (12):0.483 (12). The dioxane ring is in a half-chair conformation and the two -CH(2)- groups of this ring are disordered over two sets of sites, the ratio of refined occupancies being 0.855 (19):0.145 (19). The essentially planar thio-phene ring [largest deviation = 0.0444 (2) Å] forms a dihedral angle of 19.59 (3)° with the benzene ring.

4-[Tris(1H-pyrazol-1-yl)meth-yl]phenol.

The title compound, C(16)H(14)N(6)O, was prepared by the condensation of 4-(trifluoro-meth-yl)phenol and sodium pyrazol-1-ide in a yield of 58%. The dihedral angles formed by the planes of the pyrazole rings are 50.7 (2), 71.2 (3) and 95.8 (2)°. The mol-ecules are associated into dimers by pairs of inter-molecular O-H⋯N hydrogen bonds involving the hy-droxy groups and pyrazole N atoms. In addition, π-π stacking between the phenol rings of these inversion-related dimers is observed, with a ring centroid-to-centroid distance of 3.9247 (10) Å.

{N,N-Bis[2-(diphenyl-phosphan-yl)eth-yl]-aniline}(η-dibenzyl-ideneacetone)-palladium(0).

In the title complex, [Pd(C(34)H(33)NP(2))(C(17)H(14)O)], the Pd(0) atom is coordinated in a trigonal planar geometry formed by two P atoms of a bis-[(diphenyl-phosphino)eth-yl]aniline ligand and a C=C (η(2)) bond involving the C atoms that are in the α,ß positions relative to the central ketone of the dibenzyl-ideneacetone ligand.

Metal-interrupted perylene diimide: toward a new class of tunable n-type inorganic-organic hybrid semiconductors.

In organic thin-film transistors (OTFTs), organic electron-transport materials (n-type semiconductors) are well behind the advances in development of hole-transport materials (p-type semiconductors). Currently, one class of organic n-type semiconductor materials that is widely utilized is N,N'-dialkyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-R) derivatives with high electron affinities (EAs), such as N,N'-dioctyl-3,4,9,10-perylenetetracarboxylic diimide with a reported EA as high as 4.4 eV. The PTCDI-R derivatives have been manipulated by adding substituents on the perylene moiety or at the amine position to afford more stable compounds and higher EAs. On the basis of these materials, we have developed metal-containing perylenediimide analogues, placing a salpen ligand for metal ion chelation between two n-isobutylnaphthalimides. We demonstrate here that the electronic properties of this class of materials can be systematically tuned in a divergent manner by simply changing the metal center. The synthesis, characterization, electrochemistry, and band-gap analysis are discussed herein.

Metal-controlled assembly of near-infrared-emitting pentanuclear lanthanide beta-diketone clusters.

Metal-controlled assembly results in a series of lanthanide clusters with the formula of Ln(5)(DBM)(10)(OH)(5) x n(solvent) (DBM = dibenzoylmethanido; Ln = Nd (1), Gd (2), Er (3), and Yb (4); solvent = CH(3)CN or toluene). These pentanuclear clusters with square-pyramidal core structures have been characterized by X-ray diffraction analysis. Clusters 1, 3, and 4 show typical near-infrared (NIR) luminescence upon excitation at 350 nm, which represents the first examples of pentanuclear lanthanide clusters with sensitized NIR emission.

Europium complexes of a novel ethylenedioxythiophene-derivatized bis(pyrazolyl)pyridine ligand exhibiting efficient lanthanide sensitization.

A new class of highly luminescent nine-coordinated europium(III) tris(beta-diketonate) bis[(ethylenedioxythiophene)pyrazolyl]pyridine (L) complexes has been synthesized and the photophysical properties studied: 1 = Eu(hfac)(3)(L); 2 = Eu(tta)(3)(L); 3 = Eu(btfac)(3)(L). The solid-state structure of complex 1 has been determined by single-crystal X-ray crystallography and shows the geometry of the local coordination environment around the Eu(III) ion to be a slightly distorted tricapped trigonal prism. Luminescence lifetimes were found to be 581, 473, and 576 micros for complexes 1-3, respectively. Absolute quantum yields for complexes 1-3 were measured as 16.4 +/- 1.4%, 27.5 +/- 1.2%, and 22.2% +/- 0.3%, respectively.

Electropolymerization of a Ruthenium(II) Bis(pyrazolyl)pyridine Complex to Form a Novel Ru-Containing Conducting Metallopolymer.

A new derivative of 2,6-bis(pyrazol-1-yl)pyridine (bpp) symmetrically substituted with 3,4-ethylenedioxy-thienyl (EDOT) substituent groups, and the corresponding ruthenium(II) complex was synthesized and characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and single-crystal X-ray diffraction. A new linear conducting metallopolymer consisting of [Ru(bpp-(EDOT)(2) )(terpy)](2+) fragments was deposited directly on to electrode surfaces as a transparent, deep red film by electrochemical coupling of the pendant EDOT moieties. XPS analysis reveals that the film has the expected structure consisting of monomer repeats without degradation or loss of metal ions. Additionally, the absorption spectrum of the polymer film shows a broad absorption range from 310 to 700 nm.

Potassium bis-(1,1,1,5,5,5-hexa-fluoro-pentane-2,4-dionato)bis-(4,4,4-trifluoro-1-phenyl-butane-1,3-dionato)europate(III).

In the crystal structure of the title complex, K[Eu(C(5)HF(6)O(2))(2)(C(10)H(6)F(3)O(2))(2)], the Eu(III) ion is in a slightly distorted square-anti-prismatic coordination geometry which is defined by eight O atoms of the anionic ß-diketone ligands. The two K(+) ions lie on crystallographic inversion centers. The Eu-O bond distances are in the range 2.294 (5)-2.413 (5) Å. The crystal used was a non-merohedral twin, the ratio of the twin domains being 0.5236 (5):0.4764 (5).