Herstellung organischer Dünnstschichten

In this paper we present different experiments describing the fabrication and characterisation of self-assembled monolayers of organothiols and also discuss some of the most important applications of these systems. The reader may practise the fabrication and characterisation of self-assembled monolayers with different endgroups by adsorption of CH₃- and Oh-terminated alkanethiols on copper-coins (1 or 2 Pfenningcoins). Then patterned self-assembled monolayers of CH₃- and OH-terminated alkanethiols are produced by applying the microcontact printing technique. When these gratings are wet with water-e.g. by breathing into the surfaces-the water adsorbs onto the hydrophilic OH-terminated areas but not on the hydrophobic CH₃-terminated regions. Illumination with a laser then produces bright diffraction spots which disappear when the water evaporates. Finally, we briefly discuss applications of the self-assembled ultrathin films as sensor-devices and as substrates for CVD (chemical vapour deposition).     

DNA Microarrays

The complete human genes (ca. 100 000) as well as the whole spectrum of biological diversity should soon be able to be analyzed simultaneously by means of DNA microarrays using the fast technical advances that are occurring in this area. The particular strength of array analysis, typically based on the hybridization of nucleic acid probes attached to microchips with labeled RNA or DNA samples, results from the highly redundant measurement of many parallel hybridization events (see picture), which leads to an extraordinary level of assay validation.     

Investigation of airborne nanopowder agglomerate stability in an orifice under various differential pressure conditions

The stability of agglomerates is not only an important material parameter of powders but also of interest for estimating the particle size upon accidental release into the atmosphere. This is especially important when the size of primary particles is well below the agglomerate size, which is usually the case when the size of primary particles is below 100 nm. During production or airborne transportation in pipes, high particle concentrations lead to particle coagulation and the formation of agglomerates in a size range of up to some micrometers. Binding between the primary particles in the agglomerates is usually due to van der Waals forces. In the case of a leak in a pressurized vessel (e.g. reactor, transport pipe, etc.), these agglomerates can be emitted and shear forces within the leak can cause agglomerates to breakup. In order to simulate such shear forces and study their effect on agglomerate stability within the airborne state, a method was developed where agglomerate powders can be aerosolized and passed through an orifice under various differential pressure conditions. First results show that a higher differential pressure across the orifice causes a stronger fragmentation of the agglomerates, which furthermore seems to be material dependent.     

Apoenzyme Reconstitution as a Chemical Tool for Structural Enzymology and Biotechnology

Enzymes with artificial cofactors : Nondiffusible organic cofactors of enzymes can often be replaced by artifical analogues to generate semisynthetic enzymes (see scheme). This approach can be used to study structure–function relationships in enzymology and to produce novel enzymes with enhanced or even entirely new functions that are useful for biosensing, biocatalysis, and materials science applications.

     

Growth Mechanism of Metal–Organic Frameworks: Insights into the Nucleation by Employing a Step‐by‐Step Route

One step at a time : The in situ monitoring of the step‐by‐step formation of metal–organic frameworks (MOFs) by using surface plasmon resonance (SPR), allows the nucleation process and the formation of the secondary building units to be investigated. Growth rates on functionalized organic surfaces with different crystallographic orientations can also be studied.