The ability of temperature and pH responsive cross-linked poly(NIPAM-co-AAc) hydrogel beads containing covalently bound N-aza-crown ethers to selectively complex 90Sr and 60Co under competitive and non-competitive conditions is demonstrated using a combination of autoradiography and scintillation measurements. Due to the presence of copolymerised acrylic acid, which is incorporated to introduce pH responsive behaviour as well as acting as the site of covalent attachment of the N-aza-crown ether, the decrease in particle diameter as a function of increasing temperature on going through the LCST of PNIPAM is reduced in the presence of electrolyte. At pH 2 no complexation of either 90Sr or 60Co was observed. At pH 7 the incorporation of acrylic acid under non-competitive conditions results in the ability to complex ca. 90% 90Sr and 60Co which increases to between 94% and 96% on inclusion of N-aza-crown ether. Under competitive conditions the hydrogels lose the ability to selectively complex 90Sr, although the selectivity for 60Co was enhanced in the presence of N-aza-crown ether. Subsequent recovery of bound 60Co from the hydrogel on lowering to pH 2 was only partially successful, and lead to a decrease in the swelling behaviour on readjustment to pH 7.

We report the synthesis and properties of two different hydrogels based on N-isopropylacrylamide/acrylic acid and copolymers of oligo-ethylene glycol methacrylates incorporating N-Aza crown ethers. Both hydrogels show rapid response to environmental stimuli and their size can be tuned by pH and temperature. Swollen states lead to high adsorption of water and high contact surface area with ions whereas in the collapsed state the material releases water and the ions not selectively retained by the polymer. Preliminary autoradiography tests show that these materials strongly bind 90Sr and both pH and temperature can be used to fine tune binding selectivity. This results in such materials being promising candidates for use as smart scavenging agents for radioactive decontamination.

Two terthiophenes bearing core fluorinated thienyl units have been synthesised as potential semiconductor materials for organic field-effect transistors. Polymerisation of these compounds has been achieved using conventional iron(III) chloride oxidative coupling methods and by electrochemical oxidation. Characterisation of the fluorinated materials has been achieved by absorption spectroscopy and cyclic voltammetry. A soluble hexyl-functionalised polymer (poly8b) was used in an OFET device; hole mobilities were measured up to 3 x 10(-3) cm(2).V-1.s(-1), and the device had an on/off ratio of 10(5) and a turn-on voltage of +4V.

1,4,8,11-Methyl-substituted 6,13-triethylsilylethynylpentacene shows extended pi-pi overlap when deposited from solution, yielding organic thin film transistors with high and reproducible hole mobility with negligible hysteresis.

We suggest a link between film morphology and electrical properties of a crystalline organic semiconductor: polymer insulating blend. TIPS-Pentacene (6,13-bis(triisopropylsilylethynyl) pentacene) [J. Am. Chem. Soc. 123, 9482 (2001)] is formulated with various amorphous and semi-crystalline side chain aromatic low permittivity dielectric polymers. Film structure investigated by AFM microscopy and XPS gives invaluable information regarding film morphology and confirms potential intermolecular interaction. All these morphological observations were linked to the electrical characterisation of organic thin film transistors (OTFTs) and the determination of saturated hole mobility value. When an amorphous binder is used the more dilute the TIPS-pentacene the lower the saturated hole mobility value. When a semi-crystalline binder is used it is possible to massively dilute TIPS-pentacene within the polymer dielectric without loosing either the crystalline structure of the material or the electronic properties. Besides phase segregation, enrichment of the active interface in TIPS-Pentacene is demonstrated. [DOI: 10.1380/ejssnt.2009.455]

The morphology and organic field effect transistor (OFETs) properties of two component blends of semicrystalline 6,13-bis(triisopropylsilylethinyl)pentacene (TIPS-pentacene) with selected amorphous and semi-crystalline low permittivity side chain aromatic insulating binders deposited at room temperature under vacuum from a good solvent are reported. When blended with an amorphous binder there is evidence from XPS for strong interaction between TIPS-pentacene and binder in the solidified film giving rise to twisted TIPS-pentacene crystals containing dislocations. Due to this strong interaction we see no evidence of segregation of TIPS-pentacene towards the active interface and hence we observe a rapid fall off in saturated hole mobility at a active concentration less than 50 wt-%. When blended with a crystalline binder there is no evidence from XPS of any interaction between TIPS-pentacene and binder in the solidified film. We propose that when a crystalline binder is used, which crystallizes more slowly from solution than TIPS-pentacene, we observe stratification of the active material to both interfaces and as a result an increase of saturated hole mobility to 0.4 cm2/Vs at 20 wt-% in isotactic poly(vinylbisphenyl). The potential application of the approach are in the formulation of low cost organic semiconductors whose solution and solid state properties can be fine tuned by careful binder selection.

A series of selenophene oligomers incorporating conjugated fluorinated phenylene units have been synthesised as potential semiconductor materials for organic field-effect transistors (OFETs). X-ray crystallography shows that the molecules are held in close proximity by several short intermolecular contacts, making them ideal candidates for OFET applications.

High-throughput synthetic and screening methods have been used to prepare and evaluate caesium, cobalt and strontium selective sequestering agents derived from aza-crown ethers. Storage phosphor autoradiography was the screening method used to determine potential lead compounds. The most effective complexants for Cs+ have a very high selectivity over potassium ions and will bind picomolar quantities of Cs+ in the presence of mM K+. The binding and selectivity of these compounds with Co-60 and Sr-90 have also been investigated and selectivity was also determined with tap water and Ca2+, respectively. Experiments with tap water spiked with Cs-137 and Co-60 were carried out to confirm the decontamination capabilities of some of our compounds and a good correlation between autoradiography and these results were found.

A series of conjugated triaryl compounds have been synthesized, consisting of thiophene or selenophene peripheral units and a central 1,3,4-thiadiazole (TDA) heterocycle. X-ray crystallographic studies on four of the materials reveal that the molecules are planar in the solid state and feature an array of intramolecular (heteroatomic) and intermolecular (heteroatomic and pi-pi) noncovalent close contacts. Electrochemical oxidative polymerization affords insoluble polymers for EDOT-TDA-EDOT and EDTT-TDA-EDTT. The band gaps of the polymers have been deduced by cyclic voltammetry and electronic absorption spectroscopy and were found to be 1.8-1.9 eV. Both polymers show good stability toward n-doping and the EDTT analogue is more readily reduced than the EDOT-containing system. The enhanced stability toward n-doping, compared with the homopolymers PEDTT and PEDOT, is attributed to the presence of the electron deficient thiadiazole unit. The LUMO of poly(EDTT-TDA-EDTT) is 0.3 eV lower than that of poly(EDOT-TDA-EDOT), demonstrating that the substituent effect of the chalcogen atom is an important contributor to the electronic properties of the polymers.

[GRAPHICS]A new organic semiconductor based on a benzobisthiazole core has been studied as a hole transport material in field effect transistors; remarkably, the material self-assembles in the solid state to give intermolecular short contacts in all three dimensions.

The synthesis of regioregular poly(3-hexyl)selenophene is reported, and its optical and electrical properties are compared to those of regioregular poly(3-hexyl)thiophene.

The synthesis of five new dihalogen/interhalogen charge transfer adducts featuring cyano and nitro functionalized 1,3-dithiole-2-thiones have been prepared and characterized by x-ray crystallography. The structures feature a complex series of intermolecular close contacts between heteroatoms, as well as hydrogen bonding, to give highly ordered, polymeric assemblies. The adduct 4.IBr crystallizes in a noncentrosymmetric chiral space group and features a stack of molecules assembled through hydrogen bonds. The functional groups of all adducts participate in networks of close contacts, but do not affect the coordination environment of the dihalogen/interhalogen species. (c) 2007 Wiley Periodicals, Inc.

Good quality crystalline powders of the II/VI semiconductors ME ( M = Zn or Cd , E = Se ) have been prepared in a "one-pot" wet synthesis from elemental selenium under "Birch"-type conditions using N -methyloctadecylamine as the solvent/electron transfer reagent. The CdSe and ZnSe materials have been characterised by powder X-ray diffraction (PXRD) and their band gaps.

Rigidification has been achieved in thiophene-tetrafluorophenylene architectures through strong S...F and H...F intramolecular interactions; the resulting materials are promising candidates for p-type organic field effect transistors.

A series of thiophene oligomers bearing core phenylene and fluorinated phenylene units has been synthesized as potential semiconductor materials for organic field-effect transistors (OFETs). Polymerization of these compounds has been achieved using Stille and oxidative Coupling methods. Functionalization of the phenylene unit with fluorine atoms has a marked effect on the self-assembly and electronic properties of the parent materials: the optical band gaps and highest occupied molecular orbital levels are affected with the introduction Of fluorine atoms as a result of a combination of inductive effects and rigidification of the main chain. The design of these materials has focused on the self-assembly and solution processability of the materials. All the polymers are readily Soluble in common organic solvents. Self-assembly and planarization of the fluorinated materials in the solid state are identified by a combination of X-ray diffraction studies, absorption spectroscopy, and cyclic voltammetry. The organizational behavior of the films is in contrast to the conformational freedom observed in solution (absorption spectroscopy) and in the gas phase (computational Studies). Thin-film OFETs have been fabricated for the entire polymer series. Hole mobilities have been measured Lip to 10(-3) cm(2)/(V(.)s), with high current modulation (on/off ratios up to 10(5)) and low turn-on voltages (down to 2 V). For the Stille Coupled polymers, replacement of the bridging thiophene unit with selenophene generally increases the hole mobility of the polymers.

The title compound has been reacted with I-2, IBr and ICl to afford the charge-transfer adducts 4.2I(2), 4.IBr and 4.ICl.I-2, respectively. The products have been characterised by Raman and IR spectroscopy and X-ray crystallography. The adducts contain linear S...I-X (X=I, Br or Cl) units (174-178degrees) in which the S...I contacts range from 2.534-2.597 AAngstrom. In 4.2I(2) and 4.ICl.I-2, the materials contain additional 'free' diiodine units which are held within a matrix of intermolecular contacts, predominantly through non-covalent halogen halogen and sulfur-halogen interactions. Although the functional groups in the parent molecule (4) are inert at the supramolecular level, the bromomethyl groups in the adducts contribute strong interactions through Br...Br, Br...I, Br...S and Br...H close contacts. The structures of the complexes are polymeric in nature, providing interactions in two and three dimensions.

The reactions of di(2-thienyl)mercury, 2-thienylmercury chloride and 2-furylmercury chloride with a variety of nitrogen- and phosphorus-containing ligands have been studied. The presence of the electron-withdrawing heteroatoms results in these mercurials being stronger acceptors than the corresponding phenylmercury compounds. The complexes have been characterized by elemental analysis, melting points, infrared, and 199Hg NMR spectroscopy. 2,9-Dimethyl- and 3,4,7,8-tetramethyl-phenanthroline form 1:1 chelate complexes, as does 1,2-bis(diphenylphosphino)ethane, whereas ethylenediamine and 2,2′-bipyridyl do not form complexes. Though non-chelating ligands such as 2,4′- and 4,4′-bipyridyl do not form complexes, bis(diphenylphosphino)methane forms 1:2 complexes in which the ligand bridges two mercury atoms. Monodentate ligands, such as triphenylphosphine, cause disproportionation of the organomercury chloride. 2-Thienylmercury chloride forms a 4:1 complex with 4,4′-dipyridyl disulfide in which it is believed that a molecule of the organomercurial is coordinated to both of the nitrogen and both of the sulfur atoms. Copyright © 2004 John Wiley & Sons, Ltd.

Reaction of NH(PiPr2)2 with elemental selenium in concentrated solvent conditions enables large scale preparation and improved yields of NH(PSeiPr2)2 that may be deprotonated with sodium methoxide to give NaN(PSeiPr2)2. Treatment of the sodium salt with appropriate Group 11 metal salts in methanol yields a range of trinuclear complexes. The protic solvent conditions utilized facilitate the reduction of copper(II) salts resulting in the isolation of copper(I) complexes. These new Group 11 complexes have been characterised by 1H and 31P NMR and IR spectroscopy, APCI mass spectrometry, microanalysis and X-ray crystallography. Thermolytic decomposition of the copper(I) precursors in the presence of the indium precursor, In[(SePiPr2)2N]2Cl, has been carried in the solid state using AA-MOCVD to give copper indium diselenide solid state materials CuInSe2.