Torsional lattice vibrations in molecular crystals

Atom-atom interaction potential energies derived from various sources have been used to calculate the torsional lattice vibration frequencies of crystalline benzene. The results are compared with available experimental data. The usefulness of this type of model potential is discussed.     

Chemical tools selectively target components of the PKA system

Background  

In the eukaryotic cell the cAMP-dependent protein kinase (PKA) is a key enzyme in signal transduction and represents the main target of the second messenger cAMP. Here we describe the design, synthesis and characterisation of specifically tailored cAMP analogs which can be utilised as a tool for affinity enrichment and purification as well as for proteomics based analyses of cAMP binding proteins.     

Novel U-Shaped Systems Containing an Imide-Functionalized Cleft for the Study of Solvent-Mediated Electron Transfer and Energy Transfer: Synthesis and Binding Studies

A solution to the vexing problem of investigating solvent-mediated electron transfer under conditions of frozen solvent motion may be at hand with the synthesis of novel U-shaped systems such as 1 (R=CO(2)Me) and 2 (R=CH(2)OMe), in which the imide-functionalized cleft provides the point of attachment of the "solvent" molecule, either covalently or by hydrogen bonding.     

Modeling of Phase Separation in Alloys with Coherent Elastic Misfit

Elastic interactions arising from a difference of lattice spacing between two coherent phases can have a strong influence on the phase separation (coarsening) behavior of alloys. If the elastic moduli are different in the two phases, the elastic interactions may accelerate, slow down or even stop the phase separation process. If the material is elastically anisotropic, the precipitates can be shaped like plates or needles instead of spheres and can arrange themselves into highly correlated patterns. Tensions or compressions applied externally to the specimen may have a strong effect on the shapes and arrangement of the precipitates. In this paper, we review the main theoretical approaches that have been used to model these effects and we relate them to experimental observations. The theoretical approaches considered are (i) macroscopic models treating the two phases as elastic media separated by a sharp interface, (ii) mesoscopic models in which the concentration varies continuously across the interface, and (iii) microscopic models which use the positions of individual atoms.     

High-throughput synthesis of N3-acylated dihydropyrimidines combining microwave-assisted synthesis and scavenging techniques

[reaction: see text] The solution-phase synthesis of N3-acylated dihydropyrimidines was achieved utilizing microwave flash heating both in the synthesis (acylation) and purification (scavenging) steps. Quenching times for excess anhydrides using polystyrene or silica-supported diamine sequestration reagents were reduced from several hours to minutes utilizing microwave irradiation. The use of water as sequestration agent, coupled with an efficient solid-phase extraction workup technique allowed the rapid generation of a 20-member library of N3-acylated dihydropyrimidines.     

C2-symmetric bissulfoximines as ligands in copper-catalyzed enantioselective Diels-Alder reactions

[reaction: see text] Bissulfoximines have been used as chiral ligands in copper-catalyzed enantioselective Diels-Alder reactions between acryloyl-2-oxazolidinones and cyclopentadiene. After optimizing the ligand structure, the metal source, the counterions, and the solvent, products with up to 93% ee have been obtained.