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DNA polymerase zeta catalytic subunit REV3 is known to play an important role in the repair of DNA damage induced by cross-linking and methylating agents. Here, we demonstrate that in Arabidopsis (Arabidopsis thaliana), the basic polymerase activity of REV3 is essential for resistance protection against these different types of damaging agents. Interestingly, its processivity is mainly required for resistance to interstrand and intrastrand cross-linking agents, but not alkylating agents. To better define the role of REV3 in relation to other key factors involved in DNA repair, we perform epistasis analysis and show that REV3-mediated resistance to DNA-damaging agents is independent of the replication damage checkpoint kinase ataxia telangiectasia-mutated and rad3-related homolog. REV3 cooperates with the endonuclease MMS and UV-sensitive protein81 in response to interstrand cross links and alkylated bases, whereas it acts independently of the ATP-dependent DNA helicase RECQ4A. Taken together, our data show that four DNA intrastrand cross-link subpathways exist in Arabidopsis, defined by ATP-dependent DNA Helicase RECQ4A, MMS and UV-sensitive protein81, REV3, and the ATPase Radiation Sensitive Protein 5A., (© 2015 American Society of Plant Biologists. All Rights Reserved.)

The hyphenation of HPLC and circular dichroism (CD) detection is a useful analytical tool that can significantly facilitate the analysis (e.g., the assignment of the configuration) and quantitation of chiral compounds. HPLC-CD chromatograms often exhibit a low signal-to-noise ratio compared to chromatograms obtained by conventional UV detection. In this study we demonstrate for the first time the hyphenation of Hadamard encoded multiplexing HPLC with circular dichroism detection where positive and negative signals overlap. Here, a macro control of the HPLC instrument that was developed for conventional HPLC was implemented in HPLC-CD. In the chiral analysis of racemic samples, exemplified for warfarin, the signal-to-noise ratio could be enhanced by an order of magnitude. The presented results highlight the great modularity of the software controlled implementation of multiplexing and its facile transfer to other detection techniques.

Multiplexing based on pseudo-binary modulation sequences is known to increase the signal-to-noise ratio. In this work, Hadamard transform multiplexing is used in high-performance liquid chromatography to increase the sample throughput. Using structured modulation sequences to encode and control sample injections in combination with a fitting algorithm to deconvolute the complex data allowed us to evaluate convoluted chromatograms of up to 128 samples containing three and five analytes, respectively, with good accuracy (<2% deviation). In comparison to conventional high-performance liquid chromatography the analysis time could be reduced by 30 and 55%, respectively., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Helicenes and heterohelicenes are attractive compounds with great potential in materials sciences to be used in optoelectronics as ligand backbones in enantioselective catalysis and as chiral sensors. The properties of these materials are related to the stereodynamics of these helical chiral compounds. However, little is known about features controlling stereodynamics in helicenes; in particular, for heterohelicenes the position of the heteroatom could be relevant in this respect. Herein the complete stereodynamic characterization of monoaza[5]helicenes is shown by enantioselective dynamic HPLC and DFT calculations. At variance with previous theoretical calculations, 1-aza[5]helicene shows a surprisingly high enantiomerization barrier, which is triggered by specific solvent interactions., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: For the treatment of proximal humeral fractures two major therapeutic principles can be employed: intramedullary nailing (PHN) or locking plate osteosynthesis. The aim of this study was to evaluate and compare clinical and radiological long-term outcome of proximal humeral fracture stabilization using PHN or angular stable plating., Materials and Methods: In a retrospective study between March 2009 and March 2010, we analyzed 72 out of 118 patients with unified proximal humeral fracture who had been treated at least 3 years previously using PHN (44 patients) or angular stable plating (28 patients) in a level 1 trauma center. Functional and radiological outcomes were assessed at least 3 years after trauma using the Constant and Murley score and SF-36 score., Results: According to the Neer classification, there were 31 3-part fractures (PHN: 23; plate: 8) and 41 4-part fractures (PHN: 21; plate: 20), respectively. No clinical symptoms after 3 years were observed in 42 patients, whereas in 30 patients clinical symptoms were evaluated related to pain and/or loss of function. Functional outcome using the Constant and Murley score demonstrated a total score of 73 points (ipsilateral side) vs. 88 points (contralateral side) in all evaluated patients, on average., Conclusion: Both PHN and angular stable plating are adequate treatment options for proximal humeral fractures. Both systems require precise preoperative planning and advanced surgical experience. No significant differences in long-term clinical and radiological outcome between implants regarding fracture classification, age of patient, and choice of implant were found.

A UV-induced 1,3-dipolar nucleophilic addition of tetrazoles to thiols is described. Under UV irradiation the reaction proceeds rapidly at room temperature, with high yields, without a catalyst, and in both polar protic and aprotic solvents, including water. This UV-induced tetrazole-thiol reaction was successfully applied for the synthesis of small molecules, protein modification, and rapid and facile polymer-polymer conjugation. The reaction has also been demonstrated for the formation of micropatterns by site-selective surface functionalization. Superhydrophobic-hydrophilic micropatterns were successfully created by sequential modifications of a tetrazole-modified porous polymer surface with hydrophobic and hydrophilic thiols. A biotin-functionalized surface could be fabricated in aqueous solutions under long-wavelength UV irradiation., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

1,3,4,6-Tetraketones typically undergo keto-enol tautomerism forming bis-enols stabilized by intramolecular hydrogen bonding in two six-membered rings. However, 1,3,4,6-tetraketones derived from the terpene ketone camphor and norcamphor exist as isomers with two distinguishable modes of intramolecular hydrogen bonding, namely, the formation of six- or seven-membered rings. The structural requirements for this so far unknown behavior were investigated in detail by synthesis and comparison of structural analogues. Both isomers of such 1,3,4,6-tetraketones were fully characterized in solution and in the solid state. Intriguingly, they slowly interconvert in solution by means of tautomerism-rotation cascades, as was corroborated by DFT calculations. The influence of temperature and complexation with the transition metals Pd, Rh, and Ir on the interconversion process was investigated., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Asymmetric catalysis using enantiomerically pure catalysts is one of the most widely used methods for the preparation of enantiomerically pure compounds. The separate synthesis of both enantiomerically pure compounds requires tedious and time-consuming preparation of both enantiomerically pure catalysts or chiral separation of the racemic products. Here, we report a stereochemically flexible diastereomeric rhodium(I) catalyst for asymmetric hydrogenations of prochiral (Z)-α-acetamidocinnamates and α-substituted acrylates, which changes its enantioselectivity depending on the temperature to produce each enantiomerically pure compound in high yield with constant high enantioselectivity over time. The same axially chiral rhodium(I) catalyst produces (R)-phenylalanine derivatives in enantiomeric ratios of up to 87:13 (R/S) at low temperature and up to 3:97 (R/S) of the corresponding S enantiomers after re-equilibration of the same catalyst at elevated temperature., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The phthalimidone derivatives EM12 and lenalidomide, which are both structurally related to thalidomide, are highly interesting drugs and very recently lenalidomide attracted great attention as an antitumor and immune-modulating drug in the therapy for multiple myeloma. EM12 and lenalidomide are chiral, and the stereogenic carbon C-3 in the piperidine-2,6-dione moiety of these phthalimidone derivatives is prone to interconversion due to keto-enol tautomerization. The knowledge of the enantiomerization barrier is mandatory for pharmacokinetic studies and to develop a tailored therapy using the enantiopure or racemic drug. Here, we used dynamic EKC in combination with direct-calculation methods to determine the enantiomerization barriers of EM12 and lenalidomide. The separations of the enantiomers of EM12 and lenalidomide were performed in 50 mM aqueous disodium hydrogen phosphate buffer at pH 8 and 50 mM aqueous sodium tetraborate buffer at pH 9.3, respectively, using 20 mg/mL heptakis-(2,3-diacetyl-6-sulfato)-β-CD as a chiral additive. Enantiomerization of the compounds during the electrokinetic chromatographic separation resulted in pronounced plateau formation between the well-separated enantiomers. Peak form analysis of the experimentally obtained interconversion profiles yielded the enantiomerization rate constants k1 of EM12 and lenalidomide as well as the kinetic activation parameters ΔG(‡), ΔH(‡‡), and ΔS(‡) of enantiomerization by the evaluation of temperature-dependent measurements. The enantiomerization barrier ΔG(‡) was determined to be 98.3 ± 1.0 kJ/mol; the activation parameters ΔH(‡) = 46.1 ± 2.4 kJ/mol and ΔS(‡) = -170 ± 61 J/(K·mol) for EM12 and ΔG(‡) = 91.5 ± 1.0 kJ/mol, ΔH(‡) = 62.4 ± 5.4 kJ/mol, and ΔS(‡) = -98 ± 7 J/(K·mol) for lenalidomide. These findings were corroborated by density functional theory calculations at the B3LYP/3-21G level of theory of the ground state and intermediates considering an enantiomerization pathway via a keto-enol tautomerism., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Introduction: Mechanical breakage of cephalomedullary nail osteosynthesis is a rare complication attributed to delayed fracture union or nonunion. This study presents a series of cases of breakage and secondary lag screw dislocation after cephalomedullary nailing. The aim of this study was to identify factors that contribute to cephalomedullary nail breakage., Materials and Methods: In a retrospective case series review between 02/2005 and 12/2013, we analyzed 453 patients with trochanteric and subtrochanteric fracture who had been treated by cephalomedullary nailing. Fractures were classified according to AO/OTA classification. 13 patients with cephalomedullary nail breakage were included (failure rate 2.9 %)., Results: Seven patients were women, and six men with a mean age of 72 years (range 35-94). Implant breakage occurred 6 months postoperatively (range 1-19 months). In ten cases, breakage was secondary to delayed or nonunion, which was thought to be mainly due to insufficient reduction of the fracture, and in two cases due to loss of the lag screw because of missing set screw. In one case, breakage was apparent during elective metal removal following complete fracture healing. Short-term outcome was evaluated 6 months after operative revision using Harris hip score in 11 out of 13 patients showing a mean score of 84 %. Complete radiological fracture healing has been found in 11 patients available for follow-up within 6 months after revision surgery., Discussion: Breakage of cephalomedullary nail osteosynthesis of trochanteric fractures is a severe complication. The results of our study demonstrate that revision surgery provides good clinical and radiological short-term results. Predominately, failures of trochanteric fractures are related to lack of surgeon performance. Therefore, application of the implant requires accurate preoperative planning, advanced surgical experience to evaluate the patient and the fracture classification, and precise surgical technique including attention to detail and anatomical reduction of the fracture fragments.

trans-1,2-Disubstituted diaziridines form stable enantiomers at ambient conditions because of the two stereogenic pyramidal nitrogen atoms. Functionalized trans-1,2-disubstituted diaziridines can be utilized as a chiral switching moiety between two enantiomeric states in more complex molecular structures. However, the synthesis of functionalized diaziridines is quite challenging, because of the limited tolerance of reaction conditions that can be applied. Here we present a strategy to make trans-1,2-disubstituted diaziridines accessible as versatile building blocks in C-C-bond formations, i.e., the Heck reaction, and therefore introducing aryl substituents. The synthesis of trans-1,2-dialkenyl diaziridines with terminal alkenyl substituents and their stereodynamic properties are described., (© 2014 Wiley Periodicals, Inc.)

Reactive superhydrophobic surfaces are highly promising for biotechnological, analytical, sensor, or diagnostic applications but are difficult to realize due to their chemical inertness. In this communication, we report on a photoactive, inscribable, nonwettable, and transparent surface (PAINTS), prepared by polycondensation of trichlorovinylsilane to form thin transparent reactive porous nanofilament on a solid substrate. The PAINTS shows superhydrophobicity and can be conveniently functionalized with the photoclick thiol-ene reaction. In addition, we show for the first time that the PAINTS bearing vinyl groups can be easily modified with disulfides under UV irradiation. The effect of superhydrophobicity of PAINTS on the formation of high-resolution surface patterns has been investigated. The developed reactive superhydrophobic coating can find applications for surface biofunctionalization using abundant thiol or disulfide bearing biomolecules, such as peptides, proteins, or antibodies.

Characterising chemical reactions by kinetic analysis is of fundamental importance to experimentally obtain insights into reaction mechanisms. Based on such investigations reactions can be optimised and improved catalysts designed. Enhanced reaction conditions may drastically increase the performance of the reaction in terms of yield and (enantio-) selectivity. Understanding reaction kinetics in more complex systems involving adaptive chemical and dynamic systems on a molecular level as shown here is even more challenging. Here we review recent developments in monitoring reactions including the dynamic interconversion of stereoisomers by integrating (catalysed) reactions and chemical analysis in on-column reaction chromatographic devices. These recent developments allow rapid screening of reactions in great detail and are a central tool in determining reaction pathways and to understand how to control the stereodynamics of chiral molecules.

High-performance liquid chromatography (HPLC) is an indispensable technique to separate, quantify, and identify a broad range of compounds. Recent advances in HPLC technology led to the development of ultrahigh-performance instruments that allow rapid sample analysis with high efficiency. Nevertheless, there is still the opportunity to increase the sample throughput and to improve the signal-to-noise ratio by the application of multiplexing, where the injected samples are encoded with defined sequences. The obtained signal is then deconvoluted to give conventional chromatograms. In this work we present a method and technique which can be easily implemented in commercially available HPLC instruments to perform multiplexing analysis. Using our approach, multiplexing can be performed on standard laboratory equipment by software control and offers an inherent advantage in sensitivity and minimization of analysis time, demonstrated for the analysis of highly diluted polynuclear aromatic hydrocarbon (PAH) samples in water.

Stereolabile interconverting catalysts open up the possibility of directing enantioselectivity in asymmetric synthesis by formation of diastereomeric complexes with chiral auxiliaries and deracemization. However, the stoichiometrically used auxilliaries can significantly limit the potential applications of such systems. We synthesized a new BIPHEPO tropos ligand containing achiral selectands in the backbone, which forms transient diastereomeric associates with amylose-tris-3,5-dimethylphenyl carbamate as a selector and thus deracemizes. The enantiomerically enriched BIPHEPO obtained was successfully used in the organocatalytic asymmetric double aldol addition of substituted methyl ketones to form benzaldehyde. This strategy combines an on-column deracemization with the high stereoinduction of chiral biarylphosphineoxides and opens up new possibilities in the field of self-amplified asymmetric syntheses., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The absolute configuration of (R,R)-2,3-dideuterooxirane, which has been independently determined using Coulomb explosion imaging, has been unambiguously chemically correlated with the stereochemical key reference (+)-glyceraldehyde. This puts the absolute configuration of D(+)-glyceraldehyde on firm experimental grounds., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A novel UV-initiated surface modification method for the direct functionalization of surface hydroxy groups with thiol-containing molecules (termed "thiol-ol" modification) is described. This method is based on the oxidative conjugation of thiols to hydroxy groups. We demonstrate that different thiol-containing molecules, such as fluorophores, thiol-terminated poly(ethylene glycol) (PEG-SH), and a cysteine-containing peptide, can be attached onto the surface of porous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate). Direct functionalization of other hydroxy-group-bearing surfaces, fabrication of micropatterns, and double patterning have been also demonstrated using the thiol-ol method., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

On-column reaction gas chromatography combines the power of separation and rapid analysis of reactants and reaction products with screening of reactions in a single step. Not only conversions but the reaction rates at various temperatures can be obtained from single measurements, making this approach superior to the time-consuming measurements typically performed in reaction progress analysis. However, this approach has only been used in the investigation of interconversion processes, rearrangement reactions, and only a few examples of higher-order reactions are known. Here we present the screening of immobilized gadolinium(III)-tris[(1R,4S)-3-heptafluorobutanoyl-camphor] in the Danishefsky-hetero-Diels-Alder-reaction by enantioselective on-column reaction gas chromatography utilizing cryogenic focusing to achieve catalytic conversions in this higher-order reaction and subsequent separation of the enantiomeric product mixture to determine the enantiomeric ratio. The results obtained by this approach could be transferred to the conventional batch reaction at a larger scale, demonstrating that on-column reaction chromatography provides reliable results in the screening of enantioselective reactions., (Copyright © 2014 Wiley Periodicals, Inc.)

Surprisingly stable formamide rotamers were encountered in the tetrahydroisoquinoline and morphinan series of alkaloids. We investigated the hindered rotation around the amide bond by dynamic high-performance liquid chromatography (DHPLC) and kinetic measurements of the interconversion of the rotamers which can readily be separated by HPLC as well as TLC. The experimental results of the different methods were compared to each other as well as to results obtained by DFT calculations.

In chemistry and biology, chirality, or handedness, refers to molecules that exist in two spatial configurations that are incongruent mirror images of one another. Almost all biologically active molecules are chiral, and the correct determination of their absolute configuration is essential for the understanding and the development of processes involving chiral molecules. Anomalous x-ray diffraction and vibrational optical activity measurements are broadly used to determine absolute configurations of solid or liquid samples. Determining absolute configurations of chiral molecules in the gas phase is still a formidable challenge. Here we demonstrate the determination of the absolute configuration of isotopically labeled (R,R)-2,3-dideuterooxirane by foil-induced Coulomb explosion imaging of individual molecules. Our technique provides unambiguous and direct access to the absolute configuration of small gas-phase species, including ions and molecular fragments.

The interconversion of cis and trans isomers of dipeptides containing C-terminal proline was studied by dynamic chromatography on zwitterionic chiral stationary phases at temperatures ranging from -15°C to +45°C The cis-trans isomers could be separated below 0°C and above 0-10°C plateau formation and peak coalescence phenomena occurred, which is characteristic for a dynamic process at the time-scale of partitioning. At and above room temperature, full coalescence was observed, which allowed separations of enantiomers without interference from interconversion effects. Analysis of the dynamic elution profiles of the interconverting peptides allowed the determination of isomerization rate constants and thermodynamic activation parameters (isomerization enthalpy, entropy and activation energy). In accordance with established results, isomerization rates and thermodynamic parameters were found to depend on the nature of the N-terminal amino acid. Isomerization barriers were only slightly lower than values determined with other methods but significant differences in the relative contributions of the activation enthalpy and entropy as well as isomerization rates pointed toward selector-moderated isomerization dynamics., (Copyright © 2013 Elsevier B.V. All rights reserved.)

A new approach for the investigation of a higher-order reaction by on-column reaction gas chromatography is presented. The reaction and the analytical separation are combined in a single experiment to investigate the Diels-Alder reaction of benzenediazonium-2-carboxylate as a benzyne precursor with various anthracene derivatives, i.e. anthracene, 9-bromoanthracene, 9-anthracenecarboxaldehyde and 9-anthracenemethanol. To overcome limitations of short reaction contact times at elevated temperatures a novel experimental setup was developed involving a cooling trap to achieve focusing and mixing of the reactants at a defined spot in a fused-silica capillary. This trap functions as a reactor within the separation column in the oven of a gas chromatograph. The reactants are sequentially injected to avoid undefined mixing in the injection port. An experimental protocol was developed with optimized injection intervals and cooling times to achieve sufficient conversions at short reaction times. Reaction products were rapidly identified by mass spectrometric detection. This new approach represents a practical procedure to investigate higher-order reactions at an analytical level and it simultaneously provides valuable information for the optimization of the reaction conditions.

Diaziridines are very interesting representatives of organic compounds containing stereogenic nitrogen atoms. In particular, 1,2-dialkyldiaziridines show extraordinarily high stereointegrity. The lone electron pairs of the nitrogen atoms are in trans configuration, avoiding a four-electron repulsive interaction. Furthermore, the trans configuration of the substituents at the nitrogen atoms is energetically favored because of reduced steric interactions. Therefore only two stereoisomers (enantiomers) are observed. At elevated temperatures the enantiomers are interconverting because of the limited stereointegrity of the chirotopic nitrogen atoms. The enantiomerization rate constants and the activation parameters of interconversion are of great interest. Here, we investigated the stereodynamics of a set of small 1,2-dialkyldiaziridines bearing short substituents (Me, Et, iPr, tBu), using enantioselective dynamic gas chromatography (DGC). Separation of enantiomers of all compounds, including the highly volatile 1,2-dimethyldiaziridine, was achieved using heptakis(2,3-di-O-ethyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin in 50% PS086 (w/w) as chiral stationary phase in fused silica capillaries with a length of up to 50 m. Measurements at variable temperatures were performed and reaction rate constants were determined using the unified equation of chromatography implemented in the software DCXplorer. The activation barriers at room temperature for 1-(tert-butyl)-2-ethyldiaziridine, ΔG(╪)(298K) = 123.8 kJ mol(-1) (ΔH(╪) = 115.5±2.9 kJ mol(-1), ΔS(╪) = -28±1 J mol(-1) K(-1)), and 1-ethyl-2-isopropyldiaziridine, ΔG(╪)(298K) = 124.2 kJ mol(-1) (ΔH(╪) = 113.1±2.4 kJ mol(-1), ΔS(╪) = -37±2 J mol(-1) K(-1)), were determined, representing some of the highest values observed for nitrogen inversion in diaziridines., (Copyright © 2013 Wiley Periodicals, Inc.)

We investigated the stereodynamics of 5,5'-substituted tropos BIPHEP ligands (2,2'-bis(diphenylphosphino)-biphenyls) by enantioselective dynamic high-performance liquid chromatography (DHPLC) to elucidate the influence of the substitution pattern and electronics of the substituents (methyl, methoxy, and hydroxyl groups). By temperature-dependent dynamic HPLC measurements the activation parameters ΔG(╪), ΔH(╪), and ΔS(╪) could be determined with high precision, revealing that the activation barrier of these 5,5'-substituted BIPHEP ligands ranges in a narrow band between 87.8 and 93.0 kJ mol(-1), making them highly attractive as deracemizable dynamic chiral ligands in asymmetric catalysis. Interestingly, the activation parameters are highly influenced by a hydroxyl or methoxy group in the 5,5'-position of the BIPHEP ligands., (Copyright © 2012 Wiley Periodicals, Inc.)

The investigation of the molecular dynamics of stereoisomers is of fundamental interest in chemistry, biochemistry, medicine, and related areas. In recent years enantioselective dynamic chromatography and enantioselective dynamic capillary electrophoresis (DCE) have been established as versatile tools to investigate the kinetics of interconversions of stereoisomers. The term dynamic chromatography and dynamic electrophoresis, following the term dynamic NMR (DNMR) (Grathwohl and Wüthrich, Biopolymers 20:2623-2633, 1981; Wüthrich, Angew Chem Int Ed 42:3340-3363, 2003; Binsch et al., Angew Chem Int Ed 10:570-572, 1971), stresses the dynamic (Herschbach, Angew Chem Int Ed 26:1221-1243, 1987) behavior of analytes to interconvert between two stereoisomeric forms during the separation process. If the interconversion process is slow compared to the separation of the enantiomers, which can be achieved by accelerating the separation process or lowering the temperature, partial separation with characteristic plateau formation or peak broadening is observed.This chapter gives an overview of recent advances in the study of stereodynamics of molecules by dynamic chromatography (Trapp et al., Chirality 13:403-414, 2001; D'Acquarica et al., J Sep Sci 29:1508-1516, 2006; Wolf, Chem Soc Rev 34:595-608, 2005; Wolf, Dynamic stereochemistry of chiral compounds - principles and applications. RSC Publishing, Cambridge, 2008) and capillary electrophoresis. Models and algorithms to evaluate interconversion profiles obtained by separation techniques are discussed with respect to the challenging demands of high separation efficiencies typical of modern separation techniques. Models used for evaluation are based on iterative computer simulation algorithms using the theoretical plate model (TPM) or stochastic model of chromatography, empirical calculation methods, derived from equations used in chemical engineering, namely Damköhler analysis, and direct access using the approximation function, and more recently the unified equation of chromatography, which can be applied to all kinds of first-order reactions taking place during a chromatographic or electrophoretic separation. Furthermore, areas of applications to investigate stereodynamic processes are presented and discussed to give a practical guide for using dynamic chromatography and capillary electrophoresis.

Novel 3-(perfluoroalkanoyl)-(1R)-camphorate nickel complexes immobilized to poly(dimethylsiloxane) phases are presented. Immobilized 3-(perfluoroalkanoyl)-(1R)-camphorate nickel complexes with a trifluoromethyl (CF(3); nickel(II)-bis[(1R,4S)-3-trifluoromethanoyl-10-propylenoxycamphor]-polysiloxane Ni(tfpc)(2)@PS) and a heptafluoropropyl-substituent (C(3)F(7); nickel(II)-bis[(1R,4S)-3-heptafluorobutanoyl-10-propylenoxycamphor]-polysiloxane Ni(hfpc)(2)@PS) were synthesized, characterized and immobilized to polysiloxane. Ni(hfpc)(2)@PS was immobilized with a selector content of 38% and their enantioseparation ability was compared to selector concentrations of 4% and 20%. The influence of the perfluorinated moiety as well as the effect of the selector concentration on enantioseparations were investigated. Based on different functionalized organic compounds the quality of enantioseparation was analyzed and compared., (Copyright © 2012 Elsevier B.V. All rights reserved.)

A novel technique is presented to investigate catalytic reactions by coupling a fused-silica capillary coated with an immobilized catalyst and a bare fused-silica capillary to achieve separation of the reaction products and to generate an electroosmotic flow, which drives the transport of the reactants and products through the catalytically active capillary. The principle of this technique is illustrated by the enantioselective sulfoxidation of benzylphenylsulfide with hydrogen peroxide to the corresponding sulfoxide in the presence of a vanadium(IV)-salen catalyst, which is immobilized to nonpolar polysiloxane and permanently bonded to the inner surface of the reaction capillary. The enantiomeric ratio of the reaction product is simultaneously determined by electrokinetic chromatography using 150 mg/mL sulfated β-cyclodextrin as chiral additive in 10 mM sodium dihydrogenphosphate background electrolyte at pH 8.3. In contrast to conventional enantioselective sulfoxidations of benzylphenylsulfide using the vanadium(IV)-salen catalyst, which give ees of up to 11%, an ee of up to 23% was achieved by this approach. Furthermore, the presented technique offers many more advantages, such as improved substrate selectivity using the nonpolar polysiloxane phase as a solvent, the feasibility to perform high-throughput kinetic measurements of substrate libraries, rapid screening and investigation of stereolabile compounds, that is, chiral sulfoxides, and screening of reactions using only minute amounts of reagents., (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

To deal with different kinds of DNA damages, there are a number of repair pathways that must be carefully orchestrated to guarantee genomic stability. Many proteins that play a role in DNA repair are involved in multiple pathways and need to be tightly regulated to conduct the functions required for efficient repair of different DNA damage types, such as double strand breaks or DNA crosslinks caused by radiation or genotoxins. While most of the factors involved in DNA repair are conserved throughout the different kingdoms, recent results have shown that the regulation of their expression is variable between different organisms. In the following paper, we give an overview of what is currently known about regulating factors and gene expression in response to DNA damage and put this knowledge in context with the different DNA repair pathways in plants. This article is part of a Special Issue entitled: Plant gene regulation in response to abiotic stress., (Copyright © 2011 Elsevier B.V. All rights reserved.)

We demonstrate that aldehyde-substituted donor-acceptor cruciforms [1,4-bis(arylethynyl)-2,5-distyrylbenzenes] are useful dosimeters for primary amines, primary diamines, and secondary amines. The 1,n-diamines are particularly reactive towards this dosimeter and can be detected in less than 100 ppm concentration. Using a single aldehyde-functionalized cruciform in seven different solvents allowed us to discern fourteen different amines by digital photography and statistical evaluation of the response patterns extracted as red, green, blue (RGB) values., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Background: Regardless of the simple surgical technique, the success of the subtalar arthrodesis is limited by the rate of non-unions of the arthrodesis. The functional outcome of workers compensation is known to be poorer compared to patients without pending litigation. The aim of this study was to quantify the rate of non-unions and to determine risk factors leading to failure of the osseous consolidation after arthrodesis of the subtalar joint. The outcome assessed is a general health assessment with the SF-36 questionnaire and more illness specific with the AOFAS hindfoot score. Secondly, the influence of the health insurance status of the patients with or without worker's compensation on the outcome was tested., Methods and Results: The inclusive criterion was an arthrodesis of the subtalar joint with and without autologous cancellous bone grafting and screw osteosynthesis. This cohort study included the clinical course of 115 patients with posttraumatic osteoarthritis from 2000 to 2006. The average age of the patients (n=115) was 47±11.0 years, 83% of the treated patients were men. 68% of the patients suffered of secondary osteoarthritis after calcaneal fracture. The time interval from trauma to presenting at the physician due to therapy resistant pain was in the average 5.5±9.9 years. After primary arthrodesis (n=101) of the subtalar joint osseous consolidation was proved in 55% cases, consolidation was questionable in 21% and the rate of no consolidation with revision was remarkable high with 24%. The duration of osseous consolidation was proved by plain projection radiography or computer tomography and clinical reduction of pain. For primary arthrodesis osseous consolidation was reached after 6.4±6.3 month, after secondary arthrodesis osseous consolidation was reached after 9.4±13.1 month. After revision surgery 57% of the arthrodesis healed, 12% the osseous consolidation was questionable, and the failure rate was still 12%., Conclusion: The outcome measures of the patients with SF-36 and the more functional related AOFAS hindfoot score showed poor outcome rates after subtalar fusion in posttraumatic osteoarthritis. The AOFAS hindfoot score was 47±24 points after primary arthrodesis and 46±17 points after secondary arthrodesis of the subtalar joint. The patients regained their former ability to work only in 30% after fusion of the subtalar joint. If revision surgery was necessary 8% of the patients got back to their work prior to the injury., (Copyright © 2010 European Foot and Ankle Society. Published by Elsevier Ltd. All rights reserved.)

The kinetics of the Cu(II)(bisoxazoline)-catalyzed diastereo- and enantioselective Gosteli-Claisen rearrangement of 2-alkoxycarbonyl-substituted allyl vinyl ethers has been investigated by enantioselective on-column reaction gas chromatography (ocRGC). Enantioselective ocRGC integrates (stereoselective) catalysis and enantioselective chromatography in a single microcapillary, which is installed in a GC-MS for direct analysis of conversion and selectivity. Thus, this technique allows direct differentiation of thermal and stereoselectively catalyzed reaction pathways and determination of activation parameters and selectivities of the individual reaction pathways starting from stereoisomeric reactants with high precision. Two modes of operation of enantioselective ocRGC are presented to investigate noncatalyzed, i.e., conversion of isopropyl-2-(allyloxy)but-2Z-enoate 1 to isopropyl-3R,S-methyl-2-oxy-hex-5-enoate (±)-2 and the [Cu{(R,R)-Ph-box}](SbF(6))(2)-catalyzed Gosteli-Claisen rearrangement, i.e., conversion of isopropyl-2-(but-2'E-en-1-yloxy)but-2Z-enoate (E,Z)-3 to isopropyl-3S,4S-dimethyl-2-oxy-hex-5-enoate 4b. Eyring activation parameters have been determined by temperature-dependent measurements: Uncatalyzed rearrangement of 1 to (±)-2 gives ΔG(‡) (298 K) = 114.1 ± 0.2 kJ·mol(-1), ΔH(‡) = 101.1 ± 1.9 kJ·mol(-1), and ΔS(‡) = -44 ± 5 J·(K·mol)(-1), and catalyzed rearrangement of (E,Z)-3 to 4b gives ΔG(‡)(298 K) = 101.1 ± 0.3 kJ·mol(-1), ΔH(‡) = 106.1 ± 6.6 kJ·mol(-1), and ΔS(‡) = 17 ± 19 J·(K·mol)(-1).

Since the initial discovery of genes involved in hereditary breast cancer in humans, a vast wealth of information has been published. Breast cancer proteins were shown to work as tumor suppressors primarily through their involvement in DNA-damage repair. Surprisingly, homologs of these genes can be found in plant genomes, as well. Here, we want to give an overview of the identification and characterization of the biological roles of these proteins, in plants. In addition to the conservation of their function in DNA repair, new plant-specific characteristics have been revealed. BRCA1 is required for the efficient repair of double strand breaks (DSB) by homologous recombination in somatic cells of the model plant Arabidopsis thaliana. Bioinformatic analysis indicates that, whereas most homologs of key components of the different mammalian BRCA1 complexes are present in plant genomes, homologs of most factors involved in the recruitment of BRCA1 to the DSB cannot be identified. Thus, it is not clear at the moment whether differences exist between plants and animals at this important step. The most conserved region of BRCA1 and BARD1 homologs in plants is a PHD domain which is absent in mammals and which, in AtBARD1, might be involved in the transcriptional regulation of plant development. The presence of a plant-specific domain prompted us to reevaluate the current model for the evolution of BRCA1 homologs and to suggest a new hypothesis, in which we postulate that plant BRCA1 and BARD1 have one common predecessor that gained a PHD domain before duplication. Furthermore, work in Arabidopsis demonstrates that - as in animals - BRCA2 homologs are important for meiotic DNA recombination. Surprisingly, recent research has revealed that AtBRCA2 also has an important role in systemic acquired resistance. In Arabidopsis, BRCA2 is involved in the transcriptional regulation of pathogenesis-related (PR) genes via its interaction with the strand exchange protein RAD51.

A small array was obtained from three reactive cruciform fluorophores in six different solvents. The array discerned 10 different aromatic carboxylic acids by protonation-induced fluorescence shifts, which were recorded by digital photography. This simple array can discern acids that have closely spaced pK(a) values.

The antidepressant drug tetramezine [1,2-bis-(3,3-dimethyldiaziridin-1-yl)ethane] consists of two bridged diaziridine moieties with four stereogenic nitrogen centers, which are stereolabile and, therefore, are prone to interconversion. The adjacent substituents at the nitrogen atoms of the diaziridines moieties exist only in an antiperiplanar conformation, which results in a coupled interconversion. Therefore, three stereoisomers exist (meso form and two enantiomeric forms), which epimerize when the diaziridine moieties are regarded as stereogenic units due to the coupled interconversion. Here, we have investigated the epimerization between the meso and enantiomeric forms by dynamic gas chromatography. Temperature-dependent measurements were performed, and reaction rate constants were determined using the unified equation of chromatography implemented in the software DCXplorer. The activation barriers of the epimerization were found to be ΔG(≠) = 100.7 kJ mol(-1) at 25°C and ΔG(≠) = 104.5 kJ mol(-1) at 37°C, respectively. The activation enthalpy and entropy were determined to be ΔH(≠) = 70.3 ± 0.4 kJ mol(-1) and ΔS(≠) = -102 ± 2 J mol(-1) K(-1) ., (Copyright © 2010 Wiley-Liss, Inc.)

Here, we demonstrate a versatile screening platform for NHC ligand based catalysts by coating fused-silica micro capillaries with a bonded 1,3-bismesityl-2-imidazolidinylidene ligand. Such micro capillaries can be efficiently converted into (pre)-catalysts from various organometallic precursors by solid-phase chemistry techniques and can be quantitatively screened using on-column reaction chromatography.

Phosphorylated carbohydrates are important intracellular metabolites and thus of prime interest in metabolomics research. Complications in their analysis arise from the existence of structural isomers that do have similar fragmentation patterns in MS/MS and are hard to resolve chromatographically. Herein, we present selective methods for the liquid chromatographic separation of sugar phosphates, such as hexose and pentose phosphates, 2- and 3-phosphoglycerate, dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, as well as glucosamine 1- and 6-phosphate utilizing mixed-mode chromatography with reversed-phase/weak anion-exchangers and a charged aerosol detector. The best results were obtained when the reversed-phase/weak anion-exchanger column was operated under hydrophilic interaction liquid chromatography elution conditions. The effects of various chromatographic parameters were examined and are discussed on the basis of a simple stoichiometric displacement model for explaining ion-exchange processes. Employed acidic conditions have led to the complete separation of α- and β-anomers of glucose 6-phosphate at low temperature. The anomers coeluted in a single peak at elevated temperatures (>40°C) (peak coalescence), while at intermediate temperatures on-column interconversion with a plateau in-between resolved anomer peaks was observed with apparent reaction rate constants between 0.1 and 27.8×10(-4) s(-1). Dynamic HPLC under specified conditions enabled to investigate mutarotation of phosphorylated carbohydrates, their interconversion kinetics, and energy barriers for interconversion. A complex mixture of six hexose phosphate structural isomers could be resolved almost completely.

Combination of information technology and separation sciences opens a new avenue to achieve high sample throughputs and therefore is of great interest to bypass bottlenecks in catalyst screening of parallelized reactors or using multitier well plates in reaction optimization. Multiplexing gas chromatography utilizes pseudo-random injection sequences derived from Hadamard matrices to perform rapid sample injections which gives a convoluted chromatogram containing the information of a single sample or of several samples with similar analyte composition. The conventional chromatogram is obtained by application of the Hadamard transform using the known injection sequence or in case of several samples an averaged transformed chromatogram is obtained which can be used in a Gauss-Jordan deconvolution procedure to obtain all single chromatograms of the individual samples. The performance of such a system depends on the modulation precision and on the parameters, e.g. the sequence length and modulation interval. Here we demonstrate the effects of the sequence length and modulation interval on the deconvoluted chromatogram, peak shapes and peak integration for sequences between 9-bit (511 elements) and 13-bit (8191 elements) and modulation intervals Δt between 5 s and 500 ms using a mixture of five components. It could be demonstrated that even for high-speed modulation at time intervals of 500 ms the chromatographic information is very well preserved and that the separation efficiency can be improved by very narrow sample injections. Furthermore this study shows that the relative peak areas in multiplexed chromatograms do not deviate from conventionally recorded chromatograms., (Copyright © 2010 Elsevier B.V. All rights reserved.)

A new chiral Metal-Organic Framework (MOF), named DUT-7, has been synthesized from enantiopure (S)-2,2'-spirobiindane-5,5'-dicarboxylic acid ((S)-H(2)L) and zinc nitrate. The framework of the compound has the composition Zn(4)O((S)-L)(3) as it is found for the IRMOF series, but in contrast to these MOFs, the crystal structure of DUT-7(RT) (RT: room temperature) which has to be assigned to the chiral space group P6(3)22, has a completely different topology. The Zn(4)O clusters are not coordinated in an octahedral fashion but show only C(3) symmetry and are arranged in a trigonal-prismatic manner. The framework is built of two interpenetrated nets with an acs topology related to each other by the 2-fold axes. DUT-7 is the first example of this rare framework topology constructed from Zn(4)O units. A reversible structural transformation was observed upon cooling during single crystal X-ray diffraction. The resulting crystal structure, denoted as DUT-7(LT) (LT: low temperature), is characterized by a Zn(4)O cluster not only coordinated by six linker moieties but also by two additional solvent molecules leading to an octahedral coordination of one of the zinc atoms of the cluster. This structure transformation leads to a tripled unit cell compared to DUT-7(RT) and a change of the space group to P6(5)22. The flexibility of the coordination of the metal atoms which has been observed for the first time points toward a catalytic activity of MOFs exhibiting metal atoms with a closed shell not only caused by defects in the crystal structure. The reaction of racemic 2,2'-spirobiindane-5,5'-dicarboxylic acid (rac-H(2)L) with zinc nitrate lead to a microcrystalline compound DUT-7(rac). DUT-7 and DUT-7(rac) have been characterized by X-ray powder diffraction, elemental and thermogravimetric analysis, and IR spectroscopy revealing the same framework composition for both compounds. The porosity of DUT-7 and DUT-7(rac) was proven by nitrogen and hydrogen physisorption measurements.

The investigation of the molecular dynamics of stereoisomers and the study of the kinetics of reactions, in particular of catalyzed reactions, is of fundamental interest in chemistry, biochemistry, and medicine. Understanding how to control the transition state of a reaction allows for a directed design of new catalysts and benign processes. The integration of reactions and capillary or microchip-based electrophoretic separations is highly attractive to perform on-column derivatizations or enzymatic on-column digests of peptides and proteins for further characterization. The present review article focuses on the recent advances to study the stereodynamics of molecules and reaction kinetics of catalyzed processes by means of CE. Models and algorithms to evaluate interconversion profiles obtained by electrophoretic separation techniques are discussed with respect to the challenging demands of high separation efficiencies typical for electrophoretic techniques. Models used for evaluation are based on iterative computer simulation algorithms using the theoretical plate model or stochastic model of chromatography, empirical calculation methods, derived from equations used in chemical engineering, namely Damköhler analysis, and direct access with the approximation function and more recently with the unified equation, which can be applied to all kinds of first-order reactions taking place during a chromatographic or a electrophoretic separation. Furthermore, areas of applications are presented and discussed to give a guideline for using dynamic CE and on-column reaction electrophoresis to study kinetics of reactions and dynamic processes.

Highly efficient and sophisticated separation techniques are available to analyze complex compound mixtures with superior sensitivities and selectivities often enhanced by a 2nd dimension, e.g. a separation technique or spectroscopic and spectrometric techniques. For enantioselective separations numerous chiral stationary phases (CSPs) exist to cover a broad range of chiral compounds. Despite these advances enantioselective separations can become very challenging for mixtures of stereolabile constitutional isomers, because the on-column interconversion can lead to completely overlapping peak profiles. Typically, multidimensional separation techniques, e.g. multidimensional GC (MDGC), using an achiral 1st separation dimension and transferring selected analytes to a chiral 2nd separation are the method of choice to approach such problems. However, this procedure is very time consuming and only predefined sections of peaks can be transferred by column switching to the second dimension. Here we demonstrate for stereolabile 1,2-dialkylated diaziridines a technique to experimentally deconvolute overlapping gas chromatographic elution profiles of constitutional isomers based on multiple-reaction-monitoring MS (MRM-MS). The here presented technique takes advantage of different fragmentation probabilities and pathways to isolate the elution profile of configurational isomers., (Copyright 2009 Elsevier B.V. All rights reserved.)

N-alkylated trans-diaziridines are an intriguing class of compounds with two stereogenic nitrogen atoms which easily interconvert. In the course of our investigations of the nature of the interconversion process via nitrogen inversion or electrocyclic ring opening ring closure, we synthesized and characterized the three constitutionally isomeric diaziridines 1,2-di-n-propyldiaziridine 1, 1-isopropyl-2-n-propyldiaziridine 2, and 1,2-diisopropyldiaziridine 3 to study the influence of the substituents on the interconversion barriers. Enantiomer separation was achieved by enantioselective gas chromatography on the chiral stationary phase Chirasil-beta-Dex with high separation factors alpha (1-isopropyl-2-n-propyldiaziridine: 1.18; 1, 2-diisopropyldiaziridine: 1.24; 100 degrees C 50 kPa He) for the isopropyl substituted diaziridines. These compounds showed pronounced plateau formation between 100 and 150 degrees C, and peak coalescence at elevated temperatures. The enantiomerization barriers DeltaG(double dagger) and activation parameters DeltaH(double dagger) and DeltaS(double dagger) were determined by enantioselective dynamic gas chromatography (DGC) and direct evaluation of the elution profiles using the unified equation implemented in the software DCXplorer. Interestingly, 1-isopropyl-2-n-propyldiaziridine and 1,2-diisopropyldiaziridine exhibit similar high interconversion barriers DeltaG(double dagger) (100 degrees C) of 128.3 +/- 0.4 kJ mol(-1) and 129.8 +/- 0.4 kJ mol(-1), respectively, which indicates that two sterically demanding substituents do not substantially increase the barrier as expected for a distinct nitrogen inversion process., (2009 Wiley-Liss, Inc.)

An extension of the unified equation of chromatography to directly access reaction rate constants k(1) of first-order reaction in on-column chromatography is presented. This extended equation reflects different response factors in the detection of the reaction educt and product which arise from structural changes by elimination or addition, e.g., under pseudo-first-order reaction conditions. The reaction rate constants k(1) and Gibbs activation energies DeltaG(double dagger) of first-order reactions taking place in a chromatographic system can be directly calculated from the chromatographic parameters, i.e., retention times of the educt E and product P (t(R)(A) and t(R)(B)), peak widths at half height (w(A) and w(B)), the relative plateau height (h(p)) of the conversion profile, and the individual response factors f(A) and f(B). The evaluation of on-column reaction gas chromatographic experiments is exemplified by the evaluation of elution profiles obtained by ring-closing metathesis reaction of N,N-diallytrifluoroacetamide in presence of Grubbs second-generation catalyst, dissolved in polydimethylsiloxane (GE SE 30).

The enantiomerization of thioridazine (THD) using sulfated beta-CDs (S-beta-CDs) as chiral selectors in a citrate buffer at pH 3.0 was investigated by dynamic CE. The enantiomers of THD were well separated with dual CD systems consisting of S-beta-CD and a neutral CD. The electropherograms featuring a plateau formation, which indicated the occurrence of the enantiomerization of THD were obtained. The unified equation implemented in the software program DCXplorer was employed to evaluate elution profiles and to determine rate constants of the enantiomerization of THD. Activation parameters were evaluated from temperature-dependent measurements between 15 and 25 degrees C with an increment of 2 degrees C. The enantiomerization barriers of THD in two different electrophoretic systems were determined. Comparative studies on enantioseparation of THD using S-beta-CDs with different degree of substitution and positions of sulfate substituent, such as randomly sulfate-substituted beta-CD, 18-sulfate-substituted beta-CD and heptakis(2,3-dihydroxy-6-O-sulfo)-beta-CD reveal that the interactions between chiral selectors and THD plays an important role in the enantioseparation and enantiomerization of THD.

Enantiomerization of octahedral tris(alpha-diimine)-transition metal complexes was investigated by enantioselective dynamic MEKC. Varying both the transition metal ion (Fe(2+), Fe(3+), and Ni(2+)) and the bidentate diimine ligand (1,10-phenanthroline and 2,2'-bipyridyl), the enantiomer separations were performed either in a 100 mM sodium tetraborate buffer (pH 9.3) or in a 100 mM sodium tetraborate/sodium dihydrogenphosphate buffer (pH 8.0) both containing sodium cholate as chiral surfactant. The unified equation of dynamic chromatography was employed to determine apparent reaction rate constants from the electropherograms showing distinct plateau formation. Apparent activation parameters DeltaH(double dagger) and DeltaS(double dagger) were calculated from temperature-dependent measurements between 10.0 and 35.0 degrees C in 2.5 K steps. It was found that the nature of the central metal ion and the ligand strongly influence the enantiomerization barrier. Surprisingly, complexes containing the 2,2'-bipyridyl ligand show highly negative activation entropies between -103 and -116 J (K mol)(-1) while the activation entropy of tris(1,10-phenanthroline) complexes is positive indicating a different mechanism of interconversion. Furthermore, it was found that the Ni(2+) complexes are stereostable under the conditions investigated here making them a lucent target as enantioselective catalysts.

Discovering highly efficient catalysts is of great scientific and economical interest. Advances in high-throughput assays in combination with sophisticated analytical techniques have increased the rapidity with which catalysts can be identified and optimized. Understanding how kinetics in the mechanism of catalysis is controlled by structural parameters is essential for a directed design of catalysts. To identify such rate-controlling elementary steps and to develop and refine models, comprehensive experimental kinetic data of a broad variety of substrates are necessary. In the present article concepts of high-throughput screening techniques in catalysis using gas chromatography are reviewed in a survey covering the period from 1998 to 2007. To cover also the origins of concepts and groundbreaking experiments in this research area milestones going back to 1950 are also reviewed. The first part of the review will focus on off-line gas chromatographic analysis, the second part on on-line gas chromatographic analysis covering sequential, parallelized and high-throughput multiplexing gas chromatography. The third part presents recent advances in the integration of chemical transformation and analysis in gas chromatography. The present review article describes the state-of-the-art, scope and limitations, and applications of these different high-throughput screening approaches.

The hydrogenation of 1-acetylcyclohexene, cyclohex-2-enone, nitrobenzene, and trans-methylpent-3-enoate catalyzed by highly active palladium nanoparticles was studied by high-throughput on-column reaction gas chromatography. In these experiments, catalysis and separation of educts and products is integrated by the use of a catalytically active gas chromatographic stationary phase, which allows reaction rate measurements to be efficiently performed by employing reactant libraries. Palladium nanoparticles embedded in a stabilizing polysiloxane matrix serve as catalyst and selective chromatographic stationary phase for these multiphase reactions (gas-liquid-solid) and are coated in fused-silica capillaries (inner diameter 250 microm) as a thin film of thickness 250 nm. The palladium nanoparticles were prepared by reduction of palladium acetate with hydridomethylsiloxane-dimethylsiloxane copolymer and self-catalyzed hydrosilylation with methylvinylsiloxane-dimethylsiloxane copolymer to obtain a stabilizing matrix. Diphenylsiloxane-dimethylsiloxane copolymer (GE SE 52) was added to improve film stability over a wide range of compositions. Herein, we show by systematic TEM investigations that the size and morphology (crystalline or amorphous) of the nanoparticles strongly depends on the ratio of the stabilizing polysiloxanes, the conditions to immobilize the stationary phase on the surface of the fused-silica capillary, and the loading of the palladium precursor. Furthermore, hydrogenations were performed with these catalytically active stationary phases between 60 and 100 degrees C at various contact times to determine the temperature-dependent reaction rate constants and to obtain activation parameters and diffusion coefficients.