James Y. Becker

A New Electron Donor: synthesis of 2,3,6,7-tetra(ethyltellurio)tetrathiafulvalene

Abstract A new tetratellurio substituted derivative of tetrathiafulvalene has been prepared via a direct one pot three step synthesis.

Synthesis of 2,3-dimethylthio-6-pyridyl tetrathiafulvalene: a precursor for a new system involving a direct linkage between a strong donor (D) and a strong acceptor (A)

Abstract A multi-step synthesis of a novel tetrathiafulvalene derivative involving a 4-pyridyl substituent directly attached to the TTF moiety is described.

Improved selective electrocatalytic oxidation of phenols by tyrosinase-based carbon paste electrode biosensor

Abstract Tyrosinase-based carbon paste electrodes are evaluated with respect to the viscosity and polarity of the binder liquids. The electrodes constructed using a lower viscosity mineral oil yielded a greater response to phenol and catechol than those using a higher viscosity oil of similar chemical composition. Despite its relatively high viscosity, the use of silicon oil Si PS 086 as carbon paste binder resulted in a 2-fold increase over Si AR 200 and a 4–6 fold increase (over mineral oils) in responses to phenol, p -chlorophenol, and p -cresol. Also reported is the enhanced enzyme electrode response to phenol and catechol resulting from pre-oxidation of these substrates using a plain carbon paste electrode in a series (in-line) dual electrode configuration.

Viscosity and binder composition effects on tyrosinase-based carbon paste electrode for detection of phenol and catechol

The systematic study of the effect of binder viscosity on the sensitivity of a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxane) chemical composition were used to represent a wide range of viscosities (10-60 000 mPa s(-1) at 25 degrees C) while minimizing polarity effects. The highest response for both phenol and catechol was achieved using a silicon oil binder of intermediate viscosity (100 mPa s(-1)). The binder viscosity showed no appreciable effect on the direct oxidation of phenol and catechol using a plain CPE, suggesting the involvement of diffusion kinetics in the binder matrix for the enzyme-based CPE. The effect of the relative binder concentration in the carbon paste was measured over the range of 30-70%. Optimal results were obtained using 40% silicon oil. For comparison of the viscosity effects observed with the carbon paste electrode (CPE) containing silicon oil, other low and high viscosity mineral oils and paraffin waxes were also examined.

Preparation and structure of a novel organotellurium derivative: Di(tetrathiafulvalene)telluride [(TTF)2te]

Abstract The synthesis, electrochemical properties and crystal structure of the first compound which bridges two TTF molecules via a tellurium atom are described.

Metalation reactions—XIV : The generality of the 1.3-Sigmatropic shift of hydrogen in allenyllithium compounds

Abstract Dimetalation of aliphatic 2-alkynes was observed in mild conditions in ether solution. Only 2-butyne has undergone monometalation exclusively. The dilithio compounds of 1- and 2-alkynes were attacked by electrophiles first at the 3-position. A 1.3-sigmatropic shift occurred in the monolithioallenes to give terminal acetylides. Metalation of 3-alkyne gave only a monolithiated compound in the conditions studied.

A unique molecular donor containing two tetrathiafulvalene (TTF) units fused to 1,4 - ditellurin: Synthesis, X-ray structure and cyclic voltammetry

Abstract A new molecular donor composed of two TTF moieties fused to 1,4-ditellurin ( 3 ) has been synthesized and the structure has been characterized by X-ray diffraction. The cyclic voltammetry of both 3 and its methyl analogue 4 display two reversible two-electron oxidation waves.

Electrocatalytic reduction of CO2 to oxalate by AgII and PdII porphyrins

New homegenous catalysts, AgII and PdII metalloporphyrins, were found for the electrochemical reduction of CO2 in CH2Cl2; oxalic acid and H2 were detected as products.

Semiconducting Langmuir–Blodgett films of ethylenedithiotetrathiafulvalene (EDT–TTF) derivatives bearing charged and uncharged aromatic substituents

Ethylenedithiotetrathiafulvalene (EDT–TTF) derivatives1–4 functionalised with a single aromatic ring have been synthesised and their Langmuir–Blodgett (LB) films have been assembled utilising only 25% molar ratio of fatty acid. For compounds 1, 3 and 4, predominantly Y-type deposition onto solid supports was observed with a transfer ratio close to unity. After doping with iodine vapour, the maximum in-plane conductivity values obtained were σ rt =10 -3 S cm -1 for 1 and 3, and 10 -5 S cm -1 for 4. LB deposition of 2 was not uniform and the conductivity value after doping was low. UV–VIS spectra of the LB films reveal the appearance of a charge-transfer (CT) band at λ max =ca. 900 nm for 1 and 4 after iodine doping. A solution of compound 3 exhibited a weak absorption band at ca. 665 nm which is assigned to an intramolecular CT band; the intensity of this band increases on exposure of the solution to light. This band is not observed in LB films of 3, neither as-deposited nor after doping. Molecular orbital calculations indicate that in the minimum energy conformation of 3, the pyridinium moiety is practically orthogonal to the TTF unit and this conformation may be obtained in solution, enabling charge-transfer to occur. A more linear conformation of 3 in the LB films may prevent intramolecular charge-transfer from occurring. Monolayers of 1, 3 and 4 were characterised by cyclic voltammetry which revealed two redox steps consistent with the formation of the EDT–TTF cation radical and dication, respectively.

Semiconducting Langmuir–Blodgett films of non-amphiphilic ethylenedithio–tetrathiafulvalene derivatives bearing pyridine and pyridinium substituents

Compounds 1 and 2 form stable Langmuir–Blodgett films which after iodine doping are semiconducting (σrt= 10–3 S cm–1), demonstrating that the attachment of long alkyl chains is not a prerequisite for the formation of conducting LB films of tetrathiafulvalene (TTF)-based charge-transfer complexes.