The Rearrangement of 2,2‐Diphenyl‐1‐[(E)‐2‐phenylethenyl]cyclopropane to 3,4,4‐Triphenylcyclopent‐1‐ene: a DFT Analysis

A computational study on the rearrangement of 2,2‐diphenyl‐1‐[(E)‐2‐phenylethenyl]cyclopropane ( 1 ) is presented, using density functional theory (DFT), (U)B3LYP with the 6‐31G* basis set (DFT1) and (U)M05‐2X with the 6‐311+G** basis set (DFT2). In agreement with a biradical character of the transition structure (TS) or intermediate, the potential‐energy hypersurface is lowered by the influence of three conjugated Ph groups. Surprisingly, two conformations of the geminal diphenyl group (different twist angles) induce two different minimum‐energy pathways for the rearrangement. Independent of the functional used, the first hypersurface harbors true biradical intermediates, whereas the second energy surface is a flat, slightly ascending slope from the starting material to the TS. The functional (U)M05‐2X with the basis set 6‐311+G** provides realistic energies which seem to be close to experiment. The activation energy for racemization of enantiomers of 1 is lower than that of rearrangement by 2.5 kcal mol^?1, in agreement with experiment.     

A Simple and Effective Chemical Phosphorylation Procedure for Biomolecules

A general chemical phosphorylation method based on P(III) chemistry has been developed. The system is demonstrated for the phosphorylation of oligonucleotides, directly after their synthesis on a solid support, and for the O-phosphorylation of serine, threonine, and tyrosine as well as for a serine-containing peptide.     

A spline interpolation method for solving boundary value problems of potential theory from discretely given data

An interpolation procedure using harmonic splines is described and analyzed for solving (exterior) boundary value problems of Laplace's equation in three dimensions (from discretely given data). The theoretical and computational aspects of the method are discussed. Some numerical examples are given.     

Energy Transfer from a Lumazine (= Pteridine-2,4(1H,3H)-dione) Chromophore to Bathophcnanthroline-ruthenium(II) Complexes during Hybridization Processes of DNA

We incorporated 6,7-dimethyllumazine chromophores and a [Ru^II(bathophenanthroline)] complex into different oligodeoxynucleotides, the former via the corresponding phosphoramidites of the 2′-deoxynucleosides and the latter specifically by the phosphonate approach at the 5′-end of synthetic oligonucleotides, directly in the course of their synthesis on solid support. Efficiency measurements of this energy-transfer system with the lumazine as energy donor and the Ru complex as energy acceptor allowed us to distinguish between the hybridized and the non-hybridized state of oligonucleotides. Thus, the approach should be of value in DNA probe technology for the detection of single-stranded DNA targets.     

Observations of instabilities in the corona of laser produced plasmas

Using optical probing techniques plasma jets have been observed in the underdense plasma corona of targets irradiated with green laser beams. Various experimental observations have produced evidence that the jets are generated by an instability rather than by non-uniformities in the incident laser beams.