Chapter 24: Vanadium Chloroperoxidases as Versatile Biocatalysts

In this chapter the catalytic and structural properties of the vanadium chloroperoxidases will be discussed with an emphasis on their superb activity and stability under operational conditions. These properties make these enzymes attractive catalysts in organic synthesis and allow a number of applications. Some of the more recent findings are...

Isonicotinamide self-association: The link between solvent and polymorph nucleation

We show that, in a controlled and reproducible way, specific solvents lead to specific polymorphic forms of isonicotinamide. We argue on the basis of Raman and FTIR spectroscopy that the hydrogen bonding in solution kinetically drives the nucleation towards a specific form. This generally may lead to good understanding and control of...

Photo-catalytic oxidation of cyclohexane over TiO2: A novel interpretation of temperature dependent performance

The rate of cyclohexane photo-catalytic oxidation to cyclohexanone over anatase TiO2 was studied at temperatures between 23 and 60ºC by in situ ATR-FTIR spectroscopy, and the kinetic parameters were estimated using a microkinetic model. At low temperatures, surface cyclohexanone formation is limited by cyclohexane adsorption due to unfavorable...

Single molecule charge transport: From a quantum mechanical to a classical description

This paper explores charge transport at the single molecule level. The conductive properties of both small organic molecules and conjugated polymers (molecular wires) are considered. In particular, the reasons for the transition from fully coherent to incoherent charge transport and the approaches that can be taken to describe this transition...

Liposomes with conjugates of a calix[4]arene and a Gd-DOTA derivative on the outside surface: An efficient potential contrast agent for MRI

Paramagnetic liposomes used as contrast agents in magnetic resonance imaging (MRI) often suffer from low efficacies because of slow water diffusion through the membrane. We present an approach to overcome this limitation by incorporation of a calix[4]arene based agent that expresses the chelates towards the bulk water.

Size control and compartmentalization in self-assembled nano-structures of a multisegment amphiphilew

A ‘‘multisegment amphiphile’’ has been synthesized by covalently connecting two well known building blocks, a gelator and a micelle forming surfactant. Self-assembly results in the formation of compartmentalized nano-object displaying properties inherited from both parents.

The tungsten metallome of Pyrococcus furiosus

The tungsten metallome of the hyperthermophilic archaeon Pyrococcus furiosus has been investigated using electroanalytical metal analysis and native–native 2D-PAGE with the radioactive tungsten isotope W-187 (t1/2 = 23.9 h). P. furiosus cells have an intracellular tungsten concentration of 29 mM, of which ca. 30% appears to be free tungsten,...

Densely packed Gd(III)-chelates with fast water exchange on a calix[4]arene scaffold: A potential MRI contrast agent

A pyridine-N-oxide functionalized DOTA analogue has been conjugated to a calix[4]arene and the corresponding Gd-complex was characterized with respect to its suitability as MRI contrast agent. The compound forms spherical micelles in water with a cmc of 35 mMand a radius of 8.2 nm. The relaxivity of these aggregates is 31.2 s-1 mM-1 at 25ºC and...

Visible light-driven and chloroperoxidase-catalyzed oxygenation reactions

Robust peroxidase-catalyzed enantiospecific oxyfunctionalizations can be achieved by simple light-driven in situ generation of hydrogen peroxide.

One- and two-electron reduction of molybdate reversibly bound to the archaeal tungstate/molybdate transporter WtpA

Reversible binding of the tetrahedral oxoanions MoO4 2- and WO4 2- to two carboxylato ligands of the soluble scavenger protein WtpA from the hyperthermophilic archaeon Pyrococcus furiosus enforces a quasi-octahedral MO6 coordination in which the +VI oxidation state is destabilized.

TUD-1: Synthesis and application of a versatile catalyst, carrier, material...

The three-dimensional sponge-like mesoporous material TUD-1 is straightforward to prepare. Its synthesis can readily be modified to introduce metals into the framework of TUD-1, imparting many different catalytic activities. M-TUD-1 catalysts have proven to be very active, unlimited by diffusion and very stable. By combining two metals into one...

Selective sensor utilizing a thin monolayer of b-oriented silicalite-1 crystals– magneto-elastic ribbon assembly

This report presents the development of new selective gas sensors utilizing a b-oriented silicalite-1 layer–magneto-elastic ribbon assembly. The key principle for the operation of these sensors is monitoring the changes in the resonance frequency of the Metglas® strip in relation to the concentration of a component in the gas phase. This...

Self-assembled interpenetrating networks by orthogonal self assembly of surfactants and hydrogelators

Interpenetrating networks (IPN) consist of two or more networks of different components which are entangled on a molecular scale and cannot be separated without breaking at least one of the networks. They are of great technological interest because they allow the blending of two or more otherwise incompatible properties or functions, and...

Comment on ‘Empirical versus modelling approaches to the estimation of measurement uncertainty caused by primary sampling’ by J. A. Lyn, M. H. Ramsey, A. P. Damant and R. Wood

Recently, Lyn et al. (Analyst, 2007, 132, 1231) compared two ways of estimating the standard uncertainty of sampling pistachio nuts for aflatoxins – a modelling method and an empirical method. Their case study used robust analysis of variance (RANOVA) to derive the uncertainty estimates, highlighting a substantial difference between the two: the...