bluuebunny/crossref_metadata_2025_split huggingface dataset:
Von der Ostwald‐Reifung zur Homochiralität
Authors: Noorduin Wim L. , Vlieg Elias , Kellogg Richard M. , Kaptein Bernard 
Published: November 2009

AbstractVor einhundert Jahren erhielt Wilhelm Ostwald den Nobelpreis für Chemie. Obwohl Ostwald wenig mit dem Phänomen der Chiralität befasst war, gilt eine seiner Entdeckungen, die Ostwald‐Reifung, als wegbereitend für eine kürzlich eingeführte Methode, bei der durch zermahlungsinduzierten Abrieb racemische Konglomerate praktisch quantitativ in ein einzelnes Enantiomer überführt werden. Wir erläutern hier die von Ostwald eingeführten Konzepte und geben einen Überblick über den Stand der Technik bei zermahlungsinduzierten asymmetrischen Umwandlungen. Wir werden sehen, wie nahe schon Ostwald der Entdeckung dieser Technik gekommen war.
Catalytic Functionalization of Indoles in a New Dimension
Authors: Bandini Marco , Eichholzer Astrid 
Published: November 2009

Abstract140 Years ago Adolf von Baeyer proposed the structure of a heteroaromatic compound which revolutionized organic and medical chemistry: indole. After more than a century, indole itself and the complexity of naturally occurring indole derivatives continue to inspire and influence developments in synthetic chemistry. In particular, the ubiquitous presence of indole rings in pharmaceuticals, agrochemicals, and functional materials are testament to the ever increasing interest in the design of mild and efficient synthetic routes to functionalized indole derivatives. This Review emphasizes the achievements in the selective catalytic functionalization of indoles (CC bond‐forming processes) over the last four years.
From Ostwald Ripening to Single Chirality
Authors: Noorduin Wim L. , Vlieg Elias , Kellogg Richard M. , Kaptein Bernard 
Published: November 2009

AbstractA century ago Wilhelm Ostwald received the Nobel Prize for Chemistry. Although Ostwald was never significantly involved with the phenomenon of chirality, one of his discoveries, Ostwald ripening, is thought to be involved in a recently discovered method in which grinding‐induced attrition is used to transform racemic conglomerates virtually quantitatively into a single enantiomer. In this Minireview the basic concepts developed by Ostwald will be introduced, followed by a summary of the current status of grinding‐induced asymmetric transformations. We will see how close Ostwald himself came to discovering this technique.
A simple and reliable method to conduct and monitor expression cassette integration into the Escherichia coli chromosome
Authors: Albermann Christoph , Trachtmann Natalie , Sprenger Georg A. 
Published: November 2009

AbstractWe report a method for the integration of expression cassettes into the Escherichia coli chromosome using rare and dispensable sugar degradation gene loci as sites for integration. Clones carrying successfully recombined DNA fragments in the chromosome are easily screened using a solid differential medium containing the respective sugar compound. As an example for the heterologous expression of a complex natural product biosynthesis pathway, we show the stepwise chromosomal integration of the zeaxanthin biosynthesis pathway from Pantoea ananatis into E. coli.
Cyclostreptin and Microtubules: Is a Low‐Affinity Binding Site Required?
Authors: Prussia Andrew J. , Yang Yutao , Geballe Matthew T. , Snyder James P. 
Published: November 2009

AbstractCyclostreptin (CS) is a recently discovered natural product with cytotoxic activity caused by microtubule stabilization. It is the only known microtubule‐stabilizing agent (MSA) that covalently binds to tubulin. It also exhibits the fast‐binding kinetics seen for other MSAs. Through careful peptide digestion and mass spectrometry analysis, Buey et al. found that two amino acids are labeled by CS: Asn228, near the known taxane‐binding site, and Thr220, in the type I microtubule pore. This led Buey et al. to propose Thr220 resides at the site previously predicted to be a way station or low‐affinity site. By using molecular dynamics simulations and structural considerations of the microtubule pore and tubulin dimer, we conclude that postulation of a low‐affinity site is unnecessary to explain the available experimental data. An alternative explanation views the microtubule pore as a structural entity that presents a substantial kinetic barrier to ligand passage to the known taxane‐binding site—an entry point to the microtubule lumen that becomes completely blocked if cyclostreptin is bound at Thr220. Simulations of the free dimer also suggest a common mechanism of microtubule stabilization for taxane site MSAs through their conformational effect on the M‐loop. Such an effect explains the low tubulin polymerization caused by cyclostreptin in vitro despite its covalent attachment.
From Salts to Ionic Liquids by Systematic Structural Modifications: A Rational Approach Towards the Efficient Modular Synthesis of Enantiopure Imidazolium Salts
Authors: Ríos‐Lombardía Nicolás , Busto Eduardo , Gotor‐Fernández Vicente , Gotor Vicente , Porcar Raúl , García‐Verdugo Eduardo , Luis Santiago V. , Alfonso Ignacio , García‐Granda Santiago , Menéndez‐Velázquez Amador 
Published: November 2009

AbstractThis paper reports a simple and robust modular synthetic strategy that leads to a large variety of configurationally and structurally diverse imidazole‐based chiral ionic liquids (CILs) by lipase‐catalyzed resolution. The intimate microscopic interactions of the supramolecular ionic network of these imidazolium chiral salts at the molecular level are investigated both spectroscopically (NMR, FT‐IR‐ATR) and theoretically, and a topological analysis of the experimental electron densities obtained by X‐ray diffraction of single crystals is performed. Our results support the key role played by the relative configuration of the ‐OR group on the hydrogen‐bonding pattern and its strong influence on the final physical properties of the imidazolium salt. We also obtained a reasonable correlation between the observed melting point and the non‐covalent interactions. The spectroscopic data and the topological analysis reflect the key role played by hydrogen bonds between the OH and imidazolium C2H groups in both cation–anion and cation–cation interactions, with the presence of an OH group leading to an additional inter‐cation interaction. This interaction significantly affects the properties of stereoisomeric salts. Even more interestingly, we also studied the effect of the chirality by comparing enantiopure CILs with their racemic mixtures and found that, with the exception oftrans‐Cy6‐OH‐Im‐Bn‐Br, the melting points of the racemic mixtures are higher than those of the corresponding enantiomerically pure forms. For stereoisomeric examples, we have successfully explained the differences in melting temperatures in light of the corresponding structural data. Chirality should therefore be taken into account as a highly attractive design vector in the preparation of ILs with specifically desired properties.
Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C5Me5)3MLn] Nitrile and Isocyanide Complexes
Authors: Evans William J. , Mueller Thomas J. , Ziller Joseph W. 
Published: November 2009

AbstractThe limits of steric crowding in organometallic metallocene complexes have been examined by studying the synthesis of [(C5Me5)3MLn] complexes as a function of metal in which L=Me3CCN, Me3CNC, and Me3SiCN. The bis(tert‐butyl nitrile) complexes [(C5Me5)3Ln(NCCMe3)2] (Ln=La, 1; Ce, 2; Pr, 3) can be isolated with the largest lanthanide metal ions, La3+, Ce3+, and Pr3+. The Pr3+ ion also forms an isolable mono‐nitrile complex, [(C5Me5)3Pr(NCCMe3)] (4), whereas for Nd3+ only the mono‐adduct [(C5Me5)3Nd(NCCMe3)] (5) was observed. With smaller metal ions, Sm3+ and Y3+, insertion of Me3CCN into the MC(C5Me5) bond was observed to form the cyclopentadiene‐substituted ketimide complexes [(C5Me5)2Ln{NC(C5Me5)(CMe3)}(NCCMe3)] (Ln=Sm, 6; Y, 7). With tert‐butyl isocyanide ligands, a bis‐isocyanide product can be isolated with lanthanum, [(C5Me5)3La(CNCMe3)2] (8), and a mono‐isocyanide product with neodymium, [(C5Me5)3Nd(CNCMe3)] (9). Silicon–carbon bond cleavage was observed in reactions between [(C5Me5)3Ln] complexes and trimethylsilyl cyanide, Me3SiCN, to produce the trimeric cyanide complexes [{(C5Me5)2Ln(μ‐CN)(NCSiMe3)}3] (Ln=La, 10; Pr, 11). With uranium, a mono‐nitrile reaction product, [(C5Me5)3U(NCCMe3)] (12), which is analogous to 5, was obtained from the reaction between [(C5Me5)3U] and Me3CCN, but [(C5Me5)3U] reacts with Me3CNC through CN bond cleavage to form a trimeric cyanide complex, [{(C5Me5)2U(μ‐CN)(CNCMe3)}3] (13).
Rigid‐Strut‐Containing Crown Ethers and [2]Catenanes for Incorporation into Metal–Organic Frameworks
Authors: Zhao Yan‐Li , Liu Lihua , Zhang Wenyu , Sue Chi‐Hau , Li Qiaowei , Miljanić Ognjen Š. , Yaghi Omar M. , Stoddart J. Fraser 
Published: November 2009

AbstractTo introduce crown ethers into the struts of metal–organic frameworks (MOFs), general approaches have been developed for the syntheses of dicarboxylic acid dibenzo[30]crown‐10 (DB30C10DA), dicarboxylic acid di‐2,3‐naphtho[30]crown‐10 (DN30C10DA), dicarboxylic acid bisparaphenylene[34]crown‐10 (BPP34C10DA), and dicarboxylic acid 1,5‐naphthoparaphenylene[36]crown‐10 (NPP36C10DA). These novel crown ethers not only retain the characteristics of their parent crown ethers since they can 1) bind cationic guests and 2) serve as templates for making mechanically interlocked molecules (MIMs), such as catenanes and rotaxanes, but they also present coordination sites to connect with secondary building units (SBUs) in MOFs. The binding behavior of BPP34C10DA with 1,1′‐dimethyl‐4,4′‐bipyridinium bis(hexafluorophosphate) (DMBP⋅2 PF6) has been investigated by means of UV/Vis, fluorescence, and NMR spectroscopic techniques. The crystal superstructure of the complex DMBP⋅2 PF6⊂ BPP34C10DA was determined by X‐ray crystallography. The NPP36C10DA‐based [2]catenane (H2NPP36C10DC‐CAT⋅4 PF6) and the BPP34C10DA‐based [2]catenane (H2BPP34C10DC‐CAT⋅4 PF6) were prepared in DMF at room temperature by the template‐directed clipping reactions of the planarly chiral NPP36C10DA and BPP34C10DA with 1,1′‐[1,4‐phenylenebis(methylene)]di‐4,4′‐bipyridin‐1‐ium bis(hexafluorophosphate) and 1,4‐bis(bromomethyl)benzene, respectively. The crystal structure of the dimethyl ester (BPP34C10DE‐CAT⋅4 PF6) of the [2]catenane H2BPP34C10DC‐CAT⋅4 PF6 was investigated by X‐ray crystallography, which revealed racemic R and S isomers with planar chirality present in the crystal in a 1:1 ratio. These crown ether based struts serve as excellent organic ligands to bind with transition metal ions in the construction of MOFs: the crown ethers BPP34C10DA and NPP36C10DA in the presence of Zn(NO3)2⋅4 H2O afforded the MOF‐1001 and MOF‐1002 frameworks, respectively. The crystal structures of MOF‐1001 and MOF‐1002 are both cubic and display Fm$\bar 3$m symmetry. The unit cell parameter of the metal–organic frameworks is a=52.9345 Å. Since such MOFs, containing electron‐donating crown ethers are capable of docking incoming electron‐accepting substrates in a stereoelectronically controlled fashion, the present work opens a new access to the preparation and application of MOFs.
Effect of Guest–Host Hydrogen Bonding on the Structures and Properties of Clathrate Hydrates
Authors: Alavi Saman , Udachin Konstantin , Ripmeester John A. 
Published: November 2009

AbstractTo provide improved understanding of guest–host interactions in clathrate hydrates, we present some correlations between guest chemical structures and observations on the corresponding hydrate properties. From these correlations it is clear that directional interactions such as hydrogen bonding between guest and host are likely, although these have been ignored to greater or lesser degrees because there has been no direct structural evidence for such interactions. For the first time, single‐crystal X‐ray crystallography has been used to detect guest–host hydrogen bonding in structure II (sII) and structure H (sH) clathrate hydrates. The clathrates studied are the tert‐butylamine (tBA) sII clathrate with H2S/Xe help gases and the pinacolone + H2S binary sH clathrate. X‐ray structural analysis shows that the tBA nitrogen atom lies at a distance of 2.64 Å from the closest clathrate hydrate water oxygen atom, whereas the pinacolone oxygen atom is determined to lie at a distance of 2.96 Å from the closest water oxygen atom. These distances are compatible with guest–water hydrogen bonding. Results of molecular dynamics simulations on these systems are consistent with the X‐ray crystallographic observations. The tBA guest shows long‐lived guest–host hydrogen bonding with the nitrogen atom tethered to a water HO group that rotates towards the cage center to face the guest nitrogen atom. Pinacolone forms thermally activated guest–host hydrogen bonds with the lattice water molecules; these have been studied for temperatures in the range of 100–250 K. Guest–host hydrogen bonding leads to the formation of Bjerrum L‐defects in the clathrate water lattice between two adjacent water molecules, and these are implicated in the stabilities of the hydrate lattices, the water dynamics, and the dielectric properties. The reported stable hydrogen‐bonded guest–host structures also tend to blur the longstanding distinction between true clathrates and semiclathrates.
BCN: A Graphene Analogue with Remarkable Adsorptive Properties
Authors: Raidongia Kalyan , Nag Angshuman , Hembram K. P. S. S. , Waghmare Umesh V. , Datta Ranjan , Rao C. N. R. 
Published: November 2009

AbstractA new analogue of graphene containing boron, carbon and nitrogen (BCN) has been obtained by the reaction of high‐surface‐area activated charcoal with a mixture of boric acid and urea at 900 °C. X‐ray photoelectron spectroscopy and electron energy‐loss spectroscopy reveal the composition to be close to BCN. The X‐ray diffraction pattern, high‐resolution electron microscopy images and Raman spectrum indicate the presence of graphite‐type layers with low sheet‐to‐sheet registry. Atomic force microscopy reveals the sample to consist of two to three layers of BCN, as in a few‐layer graphene. BCN exhibits more electrical resistivity than graphene, but weaker magnetic features. BCN exhibits a surface area of 2911 m2 g−1, which is the highest value known for a BxCyNz composition. It exhibits high propensity for adsorbing CO2 (≈100 wt %) at 195 K and a hydrogen uptake of 2.6 wt % at 77 K. A first‐principles pseudopotential‐based DFT study shows the stable structure to consist of BN3 and NB3 motifs. The calculations also suggest the strongest CO2 adsorption to occur with a binding energy of 3.7 kJ mol−1 compared with 2.0 kJ mol−1 on graphene.
A Facile Circular Dichroism Protocol for Rapid Determination of Enantiomeric Excess and Concentration of Chiral Primary Amines
Authors: Nieto Sonia , Dragna Justin M. , Anslyn Eric V. 
Published: November 2009

AbstractA protocol for the rapid determination of the absolute configuration and enantiomeric excess (ee) of α‐chiral primary amines with potential applications in asymmetric reaction discovery has been developed. The protocol requires derivatization of α‐chiral primary amines through condensation with pyridine carboxaldehyde to quantitatively yield the corresponding imine. The CuI complex with 2,2′‐bis (diphenylphosphino)‐1,1′‐dinaphthyl (BINAPCuI) with the imine yields a metal‐to‐ligand charge‐transfer (MLCT) band in the visible region of the circular dichroism (CD) spectrum upon binding. Diastereomeric host–guest complexes give CD signals of the same signs but different amplitudes, allowing for differentiation of enantiomers. Processing the primary optical data from the CD spectrum with linear discriminant analysis (LDA) allows for the determination of the absolute configuration and identification of the amines, and processing with a supervised multilayer perceptron artificial neural network (MLP‐ANN) allows for the simultaneous determination of the ee and concentration. The primary optical data necessary to determine the ee of unknown samples is obtained in two minutes per sample. To demonstrate the utility of the protocol in asymmetric reaction discovery, the ee values and concentrations for an asymmetric metal‐catalyzed reaction are determined. The potential of the application of this protocol in high‐throughput screening (HTS) of ee is discussed.
B‐cell fate decisions following influenza virus infection
Authors: Rothaeusler Kristina , Baumgarth Nicole 
Published: November 2009

AbstractRapidly induced, specific Ab generated in extrafollicular foci are important components of early immune protection to influenza virus. The signal(s) that prompt B cells to participate in extrafollicular rather than germinal center responses are incompletely understood. To study the regulation of early B‐cell differentiation events following influenza infection, we exploited earlier findings of a strong contribution of C12 idiotype‐expressing B cells to the primary HA‐specific response against influenza A/PR/8/34. Using an idiotype‐specific mAb to C12 and labeled HA, in conjunction with multicolor flow cytometry, we followed the fate of C12Id‐expressing influenza HA‐specific B cells in WT BALB/c mice, requiring neither genetic manipulation nor adoptive cell transfer. Our studies demonstrate that HA‐specific C12Id+ B cells are phenotypically indistinguishable from follicular B cells. While they induced both extrafollicular and germinal center responses, extrafollicular responses were strongly predominant. Provision of increased HA‐specific T‐cell help increased the magnitude of the extrafollicular response, but did not shift the C12Id+ response toward germinal center formation. Collectively the data are consistent with the hypothesis that B‐cell fate determination following activation is a stochastic process in which infection‐induced innate signals might drive the preferential expansion of the early extrafollicular response.
Non‐pharmacological approaches for dementia that informal carers might try or access: a systematic review
Authors: Hulme Claire , Wright Judy , Crocker Tom , Oluboyede Yemi , House Allan 
Published: November 2009

AbstractObjectiveTo review non‐drug treatments for dementia; to provide a source of evidence for informal carers who want ideas about non‐drug approaches for dementia, that they might try or that they could try to access. The systematic review addresses: what non‐drug treatments work and what do they work for? What non‐drug treatments might work and what for? What non‐drug treatments do not work?MethodsLiterature searches of seven electronic databases (AMED, CINAHL, EMBASE, MEDLINE, PSYCINFO, Cochrane Library of Systematic Reviews and DARE) were carried out in November 2007 using the following search terms (or derivatives): dementia/Alzheimer's AND Review AND non‐drug therapies and aimed at finding systematic reviews.ResultsThirty‐three reviews were identified; 25 were judged to be high or good quality. Studies within these systematic reviews were characterised by weak study designs with small sample numbers. Three interventions were found to be effective for use with particular symptoms of dementia: music or music therapy, hand massage or gentle touch and physical activity/exercise.ConclusionsWhilst informal carers can apply some of the interventions highlighted in the home setting at little or no cost to themselves or to health or social care services, others are likely to require training or instruction. Service providers and commissioners should explore current and future provision of more structured group activities for people with dementia; in particular the provision of group music therapy and group exercise activities that meet the needs of both the person with dementia and their carer. Copyright © 2009 John Wiley & Sons, Ltd.
Choosing choice?
Authors: Mendis Dulani 
Published: November 2009

AbstractPatient Choice is currently a favoured public service delivery model here we review the meaning of this with reference to previous public service models. We also consider the possible effects of increasing choice on efficiency, equity, quality and user‐responsiveness with a further discussion on the financial implications in the context of the politics and the financing of the National Health Service. Copyright © 2009 John Wiley & Sons, Ltd.
Is moderate substance use associated with altered executive functioning in a population‐based sample of young adults?
Authors: Piechatzek Michaela , Indlekofer Friedrich , Daamen Marcel , Glasmacher Christoph , Lieb Roselind , Pfister Hildegard , Tucha Oliver , Lange Klaus W. , Wittchen Hans‐Ulrich , Schütz Christian G. 
Published: November 2009

AbstractBackgroundSubstance use (SU) has been linked with impaired cognitive functioning. Evidence comes mainly from clinical studies or studies examining heavy users. Though, the majority of users are not involved in heavy use. This study investigates the association between moderate use and cognition in a population‐based sample.MethodsA total of 284 young adults with ecstasy, cannabis or alcohol use and a control group were sampled from the EDSP database for participation in the Munich Assessment of Young Adults (MAYA) study. Subjects completed a comprehensive battery of neuropsychological tests (executive functions, working memory and impulsivity). Multiple linear regression models were conducted to examine the relationship between use and cognitive performance.ResultsIncreased ecstasy consumption was associated with increased error‐proneness (Stroop task, CANTAB ID/ED‐shift, spatial working memory). More frequent cannabis use and more extensive alcohol consumption were associated with a higher degree of impulsiveness.ConclusionsBased on mild to moderate SU, little indication of differences in executive functioning was found. For ecstasy use, an increased error‐proneness was revealed. The subtle differences in relatively young individuals warrant further investigation in prospective long‐term studies to identify subjects at risk, and to examine effects of prolonged patterns of use on executive functioning. Copyright © 2009 John Wiley & Sons, Ltd.
Associations between plasma levels of 3‐methoxy‐4‐hydroxyphenylglycol (MHPG) and negative symptoms or cognitive impairments in early‐stage schizophrenia
Authors: Goto Naoki , Yoshimura Reiji , Kakeda Shingo , Moriya Junji , Hayashi Kenji , Ikenouchi‐Sugita Atsuko , Umene‐Nakano Wakako , Hori Hikaru , Ueda Nobuhisa , Korogi Yukunori , Nakamura Jun 
Published: November 2009

AbstractSchizophrenic patients demonstrate a variety of cognitive deficits, including attention, executive functions, and working memory, even in the early stage of disease. In the present study, we examined the association between blood levels of 3‐methoxy‐4‐hydroxyphenylglycol (MHPG), homovanillic acid (HVA), or brain‐derived neurotrophic factor (BDNF) and scores on the Wisconsin Card Sorting Test (WCST) in patients with early‐stage schizophrenia. We also investigated the association between frontal GABA levels using 1H‐magnetic resonance spectroscopy (MRS) at 3T and scores on the WCST in the same patients. Blood levels of BDNF and catecholamine metabolites and brain GABA levels using 1H‐MRS were measured in 18 schizophrenic patients (nine males, nine females; age range 13–52 year). A significantly positive correlation was observed between plasma MHPG levels and %PEM (rho = −0.686,p = 0.0047). A trend toward negative correlation was found between frontal lobe GABA levels and the per cent of preservation error (%PEM) in the early stage of schizophrenia (rho = −0.420,p = 0.0836). These results suggest that noradrenergic neurons might be involved in neuropsychological functions in early‐stage of schizophrenia. Copyright © 2009 John Wiley & Sons, Ltd.