A Geomimetic Approach to the Formation and Identification of Fossil Sterane Biomarkers in Crude Oil: 18‐nor‐D‐homo‐Androstane and 5α,14β‐Androstane

A diazonium ion derived from 18‐aminoandrostane rearranged upon decomposition by a carbonium and a carbenium ion to furnish a mixture of a cyclopropanated compound and two D ‐homo‐androstenes. Hydrogenation of this mixture gave the saturated hydrocarbons, 18‐nor‐D ‐homo‐androstane and 5α,14β‐androstane, which are both fossil sterane biomarkers in Neoproterozoic crude oil. The so far unknown constitution and configuration as well as the geochemical genesis were established by this experiment. The starting material for this investigation, 18‐aminoandrostane, was prepared in twelve steps from androstan‐17‐one (12.5 % overall yield) with a Barton reaction as the key step.     

Porous organic alloys

Another brick in the wall: Porous ternary cocrystals were prepared by chiral recognition between organic cage modules. One module, CC1, is ordered on 50?% of the lattice positions with respect to two other modules, CC3 and CC4, that are disordered across the other 50?% of sites (see picture). There is a linear relationship between relative module composition and the cocrystal lattice parameters.     

LNAzymes: incorporation of LNA-type monomers into DNAzymes markedly increases RNA cleavage

Incorporation of two alpha-L-LNA/LNA nucleotides into each of the two binding arms of a "10-23" DNAzyme has been accomplished and the RNA cleavage with these novel LNAzymes studied. In comparison with the unmodified DNAzyme, the LNAzymes show significantly improved cleavage of the phosphodiester backbone at the target nucleotide in a small RNA substrate (58n RNA) under single-turnover conditions. The LNAzymes show efficient multiple turnover. With the LNAzymes, efficient cleavage was accomplished also of a naturally occurring ribosomal RNA at a target site within a highly structured region. The reference DNAzyme was ineffective at cleaving the ribosomal RNA target.     

Combining microscale solution-phase isoelectric focusing with Multiplexed Proteomics dye staining to analyze protein post-translational modifications

Previously, a strategy for rapidly identifying mitochondrial phosphoproteins was presented that involves prefractionating multisubunit complexes by sucrose gradient centrifugation, followed by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and selective staining of phosphoproteins and total protein with fluorescent dyes [1]. Though suitable for evaluating the mitochondrial proteome, which consists of numerous multisubunit complexes, the strategy is not generally applicable to other complex proteomes. We determined that prefractionating samples by solution-phase isoelectric focusing is an effective alternative to sucrose-gradient fractionation that can be applied equally well to the analysis of mitochondrial and plasma proteins. Fluorescence-based multiplexing dye technologies greatly extend the capacity of SDS-polyacrylamide gel electrophoresis with respect to the investigation of proteome-wide changes in protein expression and post-translational modification, such as phosphorylation and glycosylation [2]. Overall, the prefractionation/Multiplexed Proteomics staining technology permits rapid, higher throughput screening of specimens for the identification of potentially interesting fractions that can subsequently be evaluated more thoroughly by two-dimensional gel electrophoresis.     

Synthesis, characterisation and optical spectroscopy of platinum(II) di-ynes and poly-ynes incorporating condensed aromatic spacers in the backbone

A series of protected and terminal dialkynes with extended pi-conjugation through a condensed aromatic linker unit in the backbone, 1,4-bis(trimethylsilylethynyl)naphthalene, 1,4-bis(ethynyl)naphthalene, 9,10-bis(trimethylsilylethynyl)anthracene, 9,10-bis(ethynyl)anthracene, have been synthesized and characterized spectroscopically. The solid-state structures of and have been confirmed by single crystal X-ray diffraction studies. Reaction of two equivalents of the complex trans-[Ph(Et(3)P)(2)PtCl] with an equivalent of the terminal dialkynes 1,4-bis(ethynyl)benzene and, in (i)Pr(2)NH-CH(2)Cl(2), in the presence of CuI, at room temperature, afforded the platinum(II) di-ynes trans-[Ph(Et(3)P)(2)Pt-C[triple bond, length as m-dash]C-R-C[triple bond, length as m-dash]C-Pt(PEt(3))(2)Ph](R = benzene-1,4-diyl; naphthalene-1,4-diyl and anthracene-9,10-diyl ) while reactions between equimolar quantities of trans-[((n)Bu(3)P)(2)PtCl(2)] and under similar conditions readily afforded the platinum(II) poly-ynes trans-[-((n)Bu(3)P)(2)Pt-C[triple bond]C-R-C[triple bond]C-](n)(R = naphthalene-1,4-diyl and anthracene-9,10-diyl ). The Pt(II) diynes and poly-ynes have been characterized by analytical and spectroscopic methods, and the single crystal X-ray structures of and have been determined. These structures confirm the trans-square planar geometry at the platinum centres and the linear nature of the molecules. The di-ynes and poly-ynes are soluble in organic solvents and readily cast into thin films. Optical spectroscopic measurements reveal that the electron-rich naphthalene and anthracene spacers create strong donor-acceptor interactions between the Pt(II) centres and conjugated ligands along the rigid backbone of the organometallic polymers. Thermogravimetry shows that the di-ynes possess a somewhat higher thermal stability than the corresponding poly-ynes. Both the Pt(II) di-ynes and the poly-ynes exhibit increasing thermal stability along the series of spacers from phenylene through naphthalene to anthracene.     

Identification of efficient and sequence specific bimolecular artificial ribonucleases by a combinatorial approach

Chemically modified nucleotide monomers were incorporated into adjacent terminal positions of two separate oligonucleotides complementary to an RNA target; all possible combinations of the catalytic units were tested, resulting in an artificial nuclease that showed high activity and catalytic turnover.     

UHV Studies of Methanol Decomposition on Mono‐ and Bimetallic CoPd Nanoparticles Supported on Thin Alumina Films

Bimetallic nanoparticles often turn out to be superior to the corresponding monometallic systems with respect to their catalytic properties. To study such effects for the methanol decomposition reaction, model catalysts were prepared by physical vapor deposition of Pd and Co under ultrahigh‐vacuum (UHV) conditions. Monometallic Pd and Co particles as well as CoPd core–shell particles were generated on an epitaxial alumina film grown on NiAl(110). The interaction with methanol is examined by temperature‐programmed desorption of methanol and carbon monoxide and by X‐ray photoelectron spectroscopy. The decomposition of methanol proceeds in two reaction pathways independent of the particle composition: complete dehydrogenation towards carbon monoxide and hydrogen, and C? O bond scission yielding carbon deposits. Pd is the most active material studied here. The relative importance of the two channels varies for the different particle systems: on Pd dehydrogenation is preferred, whereas the C? O bond cleavage is more pronounced on Co. The bimetallic clusters show a moderate performance for both pathways. Carbon deposition poisons the model catalysts by blocking the adsorption sites for methoxide, which is the first intermediate product during methanol decomposition. In particular on Co, large amounts of carbon deposits can also be caused by dissociation of the final product of the dehydrogenation pathway, carbon monoxide. A comparison with the results of methanol decomposition on Co, Pd, and CoPd catalysts in continuous‐flow reactors demonstrates that the findings of the present UHV study are relevant for catalytic performance under high‐pressure conditions.