Nitrogen‐Doped Carbon Capsules via Poly(ionic liquid)‐Based Layer‐by‐Layer Assembly

Layer‐by‐layer (LbL) assembly technique is applied for the first time for the preparation of nitrogen‐doped carbon capsules. This approach uses colloid silica as template and two polymeric deposition components, that is, poly(ammonium acrylate) and a poly (ionic liquid) poly(3‐cyanomethyl‐1‐vinylimidazolium bromide), which acts as both the carbon precursor and nitrogen source. Nitrogen‐doped carbon capsules are prepared successfully by polymer wrapping, subsequent carbonization and template removal. The as‐synthesized carbon capsules contain ≈7 wt% of nitrogen and have a structured specific surface area of 423 m² g⁻¹. Their application as supercapacitor has been briefly introduced. This work proves that LbL assembly methodology is available for preparing carbon structures of complex morphology.     

Asymmetric addition of a nitrogen nucleophile to an enoate in the presence of a chiral phase‐transfer catalyst: A novel approach toward enantiomerically enriched protected β‐amino acids

A proof of concept for the asymmetric organocatalytic aza‐Michael addition reaction of nitrogen nucleophiles with simple and readily available alkyl enoates as acceptor molecules in the presence of a chiral phase‐transfer catalyst has been demonstrated. The desired enantiomerically enriched β‐amino acid derivatives were obtained in up to 86% yield and with enantioselectivities of up to 37% ee. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:202–209, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21004     

New cathinone‐derived designer drugs 3‐bromomethcathinone and 3‐fluoromethcathinone: studies on their metabolism in rat urine and human liver microsomes using GC–MS and LC–high‐resolution MS and their detectability in urine

3‐Bromomethcathinone (3‐BMC) and 3‐Fluoromethcathinone (3‐FMC) are two new designer drugs, which were seized in Israel during 2009 and had also appeared on the illicit drug market in Germany. These two compounds were sold via the Internet as so‐called “bath salts” or “plant feeders.” The aim of the present study was to identify for the first time the 3‐BMC and 3‐FMC Phase I and II metabolites in rat urine and human liver microsomes using GC–MS and LC–high‐resolution MS (HR‐MS) and to test for their detectability by established urine screening approaches using GC–MS or LC–MS. Furthermore, the human cytochrome‐P450 (CYP) isoenzymes responsible for the main metabolic steps were studied to highlight possible risks of consumption due to drug–drug interaction or genetic variations. For the first aim, rat urine samples were extracted after and without enzymatic cleavage of conjugates. The metabolites were separated and identified by GC–MS and by LC–HR‐MS. The main metabolic steps were N‐demethylation, reduction of the keto group to the corresponding alcohol, hydroxylation of the aromatic system and combinations of these steps. The elemental composition of the metabolites identified by GC–MS could be confirmed by LC–HR‐MS. Furthermore, corresponding Phase II metabolites were identified using the LC–HR‐MS approach. For both compounds, detection in rat urine was possible within the authors' systematic toxicological analysis using both GC–MS and LC–MSⁿ after a suspected recreational users dose. Following CYP enzyme kinetic studies, CYP2B6 was the most relevant enzyme for both the N‐demethylation of 3‐BMC and 3‐FMC after in vitro–in vivo extrapolation. Copyright © 2012 John Wiley & Sons, Ltd.     

How many chiral centers can Raman optical activity spectroscopy distinguish in a molecule?

To study the capabilities and limitations of Raman optical activity, (-)-(M)σ-[10]helicene and (-)-(M)σ-[4]helicene serve as scaffold molecules on which new chiral centers are introduced by substitution of hydrogen atoms with other functional groups. These functional groups are deuterium atoms, fluorine atoms, and methyl groups. Multiply deuterated species are compared. Then, results of singly deuterated derivatives are compared against results obtained from singly fluorinated and methylated derivatives. The analysis required the calculation of a total of 2433 Raman optical activity spectra. The method we propose for the comparison of the various Raman optical activity spectra is based on the total intensity of squared difference spectra. This allows a qualitative comparison of pairs of Raman optical activity spectra and the extraction of the pair of most similar Raman optical activity spectra for each group of stereoisomers. Different factors were accounted for, such as the spectral resolution (modeled by line broadening) and the range of vibrational frequencies considered. In the case of σ-[4]helicene all generated stereoisomers in each group can be distinguished from one another by Raman optical activity spectroscopy. For σ-[10]helicene this holds except for the lower one of the two resolutions considered. Here, the group consisting of stereoisomers with five chiral centers contains at least one pair of derivatives whose Raman optical activity spectra cannot be distinguished from one another. This indicates that an increased molecular size has a negative effect on the number of chiral centers which can be distinguished by Raman optical activity spectroscopy. Regarding the different substituents, stereoisomers are the better distinguishable in Raman optical activity spectroscopy, the more distinct the signals of the substituent are from the rest of the spectrum.     

Unifying Typical Entanglement and Coin Tossing: on Randomization in Probabilistic Theories

It is well-known that pure quantum states are typically almost maximally entangled, and thus have close to maximally mixed subsystems. We consider whether this is true for probabilistic theories more generally, and not just for quantum theory. We derive a formula for the expected purity of a subsystem in any probabilistic theory for which this quantity is well-defined. It applies to typical entanglement in pure quantum states, coin tossing in classical probability theory, and randomization in post-quantum theories; a simple generalization yields the typical entanglement in (anti)symmetric quantum subspaces. The formula is exact and simple, only containing the number of degrees of freedom and the information capacity of the respective systems. It allows us to generalize statistical physics arguments in a way which depends only on coarse properties of the underlying theory. The proof of the formula generalizes several randomization notions to general probabilistic theories. This includes a generalization of purity, contributing to the recent effort of finding appropriate generalized entropy measures.