Quantification of deep hole-trap filling by molecular p-doping: Dependence on the host material purity

The p-doping effect of the fluorinated fullerene C₆₀ F₃₆ doped into organic thin films of N,N,N′,N′-tetrakis(4-methoxyphenyl)-benzidine (MeO-TPD) of different purification grades is systematically investigated by photoemission spectroscopy. By reducing the molar doping ratio to MR = 2.9 × 10^?4, the Fermi-level shift upon doping is resolved in particular at very low doping concentrations. In comparison to four times sublimated MeO-TPD, 5 times more C₆₀F₃₆ molecules have to be doped into unpurified MeO-TPD films to shift the Fermi-level just above its intrinsic position. This finding is discussed in terms of a statistical model, showing that narrow deep hole-trap states are additionally present in the unpurified host material which are hindering an efficient generation of free charge carriers at molar doping ratios below MR = 0.002.     

Composition of Commercial Bis(2‐ethylhexyl) Sulfosuccinate Surfactant By‐Products and their Effects on an Agrochemical Formulation

Sodium bis(2‐ethylhexyl) sulfosuccinate (known as AOT) is a commercially available surfactant commonly used in agrochemicals. Besides the principal diester surfactant, the commercial AOT product contains two surface‐active isomeric monoester by‐products, which may influence the surfactant's overall properties. This work investigates whether the purity of the surfactant affects its ability to stabilize an agrochemical formulation. The concentrations of the diester and two monoester impurities in batches of commercial AOT product from several suppliers were determined quantitatively by liquid chromatography–mass spectrometry. The tested batches showed different contents of the monoesters. Samples of a model agrochemical formulation containing the AOT product formed more sediment during storage when the content of monoesters in the surfactant was high. The supplier of an commercial AOT product could be traced by analysis of the monoester content of either the raw product or the aged agrochemical formulation.     

Hydrogenation of Cinnamaldehyde over Pd/Al2O3 Catalysts Modified with Thiol Monolayers

Modification of supported Pt catalysts with thiols has recently been shown to improve the hydrogenation selectivity of α,β-unsaturated aldehydes to unsaturated alcohols. Here, we apply a variety of organic thiol coatings to Pd/Al₂O₃ catalysts that typically have a much lower intrinsic selectivity for desired product formation. Thiol monolayers were found to increase hydrogenation selectivity to cinnamyl alcohol; however, unlike with Pt catalysts, the increase was independent of the identity of the organic tail.     

Stable linker peptides for a cellulose-binding domain-lipase fusion protein expressed in Pichia pastoris

Fusion proteins composed of a cellulose-binding domain fromNeocallimastix patriciarum cellulase A and Candida antarcticalipase B were constructed using different linker peptides. Theaim was to create proteolytically stable linkers that were ableto join the functional modules without disrupting their function.Six fusion variants containing linkers of 4–44 residueswere expressed in Pichia pastoris and analysed. Three variantswere found to be stable throughout 7-day cultivations. The cellulose-bindingcapacities of fusion proteins containing short linkers wereslightly lower compared with those containing long linkers.The lipase-specific activities of all variants, in solutionor immobilized on to cellulose, were equal to that of the wild-typelipase.