bluuebunny/crossref_metadata_2025 huggingface dataset:
Modification of polyurethane‐coated fabrics by sol–gel thin films
Authors: Škoc Maja Somogyi , Macan Jelena , Pezelj Emira
Published: October 2013

Sol–gel derived silica and hybrid films from tetraethoxysilane (TEOS) and 3‐glycidyloxypropyltrimethoxysilane (GLYMO) were deposited by dip‐coating, in order to find the best treatment. GLYMO‐based treatments preserved textile feel of the material. The coatings were characterized by infrared spectroscopy (IR), scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and water contact angle measurement. IR spectra confirmed the existence of silicate network and successfully conducted modification for both precursors. DSC and TGA showed that the conditions of hydrolysis had greater influence on TEOS than GLYMO‐based treatments. Both treatments shifted the degradation onset to higher temperatures. SEM images showed that polyurethane surface and pores were completely covered and filled by silica or hybrid thin films forming a composite organic–inorganic coating. Hydrophobic effect was preserved for all the samples, except for a single treatment of the GLYMO, due to its polar epoxy group. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 39914.
Preparation and characterization of supported ordered nanoporous carbon membranes for gas separation
Authors: Zhang Bing , Shi Yi , Wu Yonghong , Wang Tonghua , Qiu Jieshan
Published: October 2013

Supported ordered nanoporous carbon membranes (ONCM) were prepared by coating a membrane‐forming solution of resorcinol‐formaldehyde (RF) resin on plate support through solvent evaporation and pyrolysis. The membrane solution was formed by the organic‐organic assembly of RF resin with Pluronic F127 in the presence of triethyl orthoacetate and catalyst hydrochloric acid. The thermal stability of precursor, the microstructure, functional groups, and morphology and porous structure of resultant support and ONCM were investigated by the techniques of thermogravimetry, X‐ray diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy/transmission electron microscopy and nitrogen adsorption‐desorption, respectively. Results have shown that the as‐obtained ONCM has well‐developed porous regularity with bi‐modal narrow pore size distribution. ONCM is tightly adhered to the adopted phenolic resin‐based carbon support. Gases permeating through the ONCM are dominated by molecular sieving mechanism. The ideal gas separation factor of the supported ONCM can be reached to 46.4, 4.7 and 3.3 for H2/N2, CO2/N2 and O2/N2, respectively. The supported ONCM obtained in this work exhibits most promising application for permanent gas separation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39925.
Synthesis, Antibacterial, and Antiviral Evaluation of New Heterocycles Containing the Pyridine Moiety
Authors: Salem Marwa S. , Sakr Sameh I. , El‐Senousy Waled M. , Madkour Hassan M. F.
Published: October 2013

A facile one‐pot four‐component reaction was utilized to construct 2‐oxo‐1,2‐dihydropyridine‐3‐carbonitrile as a scaffold for the synthesis of many fused heterocyclic systems, namely, furopyridine, pyridothiadiazepinthione, and pyridotriazine, as well as non‐fused heterocyclic systems such as phthalazin‐2(1H)‐ylnicotinonitrile, pyridin‐2‐yl‐1H‐pyrazole, and pyrazol‐1‐ylnicotino‐nitrile,1‐(3‐cyanopyridin‐2‐yl)‐1H‐pyrazole. The new compounds were evaluated as antimicrobial and antiviral agents.
Publication fees for open access journals: Different disciplines—different methods
Authors: Kozak Marcin , Hartley James
Published: October 2013

Many authors appear to think that most open access (OA) journals charge authors for their publications. This brief communication examines the basis for such beliefs and finds it wanting. Indeed, in this study of over 9,000 OA journals included in the Directory of Open Access Journals, only 28% charged authors for publishing in their journals. This figure, however, was highest in various disciplines in medicine (47%) and the sciences (43%) and lowest in the humanities (4%) and the arts (0%).
Prediction Error Based Performance Monitoring, Degradation Diagnosis and Remedies in Offset‐Free MPC: Theory and Applications
Authors: Pannocchia G. , De Luca A. , Bottai M.
Published: October 2013

We present in this paper a control performance monitoring method for linear offset‐free model predictive control (MPC) algorithms, in which the prediction error sequence is used to detect whether the internal model and the observer are correct or not. When the prediction error is a white noise signal, revealed by the Ljung‐Box test, optimal performance is detected. Otherwise, we use a closed‐loop subspace identification approach to reveal the order of a minimal realization of the system from the deterministic input to the prediction error. When such order is zero, we prove that the model is correct and the source of suboptimal performance is an incorrect observer. In such cases, we suggest an optimization method to recalculate the correct augmented state estimator. If, instead, such order is greater than zero we prove that the model is incorrect, and re‐identification is suggested. A variant for (large‐scale) block‐structured systems is presented, in which diagnosis and corrections are performed separately in each block. Two examples of different complexity are presented to highlight effectiveness and scalability of the method.
Recent issues on stochastic directional convexity, and new results on the analysis of systems for communication, information, time scales and maintenance
Authors: Ortega Eva María , Alonso José
Published: October 2013

In an earlier reference, we provided a review of the regular, sample path and strong stochastic concepts of stochastic convexity in both univariate and multivariate settings, jointly with most of their applications, and some other new results for analysing communication systems on the basis of biologically inspired models. This article provides a comprehensive discussion about the regular notion of stochastic increasing and directional convexity, denoted by SI − DCX introduced by Meester and Shanthikumar for a general partially ordered space. We study the connection of the SI − DCX property of X(θ) for θ taking on values over a sublattice and the optimal solution of a maximization problem with objective function given by the expected value of any increasing convex function of the parameterized random variable X(θ), as well as the analysis of the variability ordering of the mixture model with correlated parameters. We illustrate these results with the conditions for the SI − DCX property of the sojourn time at M ∕ δ ∕ 1 processor sharing queues, the arrival time at GI/GI/1‐queues; best monitoring scales for the ageing description; the total score for the best selected items in sequential screening; moments of multivariate distributions; l1 norms; the failure time of systems under opportunistic maintenance; performance measures of the Internet traffic and information systems. These measures are analysed as mixtures with arbitrary mixing distributions, by the increasing convex ordering, and their distributional bounds are derived. Copyright © 2013 John Wiley & Sons, Ltd.
A methodological framework for the economic evaluation of CO2 emissions from transport
Authors: Nocera Silvio , Cavallaro Federico
Published: October 2013

As the main cause of the global warming, CO2 emissions are a relevant externality in the transport sector. However, feasibility assessments do not always take these effects into adequate account, because a number of scientific and economic uncertainties make it difficult to determine a reliable estimate for a unitary CO2 cost.

This paper first analyses the methods generally used to determine the cost of CO2 emissions, showing that market‐based prices are not always suitable for this aim. Avoidance and damage cost methods are then thoroughly discussed, evaluating their pros and cons, including an extensive review of previous studies of methods for comparing costs. To determine the most reliable values, a method based on both avoidance and damage costs is proposed here.

This method is then applied to the case study of the Brenner Base Tunnel, comparing the outcomes of three different scenarios: ‘minimum’ suggests the maintenance of the ‘do‐nothing’ option (no tunnel realisation), whereas ‘trend’ and ‘consensus’ both imply the construction of the tunnel with different political choices, namely, a complete market liberalisation in trend and sustainable interventions in consensus. Results up to 2035 reveal that, in comparison with the do‐nothing option, the enlightened transport policy shown in consensus could bring about a CO2 economic saving of up to around €331m for the community, whereas a simple liberalisation (trend) increases the costs derived from global warming by about €228m. Copyright © 2013 John Wiley & Sons, Ltd.
Age and Sensory Processing Abnormalities Predict Declines in Encoding and Recall of Temporally Manipulated Speech in High‐Functioning Adults with ASD
Authors: Mayer Jennifer L. , Heaton Pamela F.
Published: October 2013

While temporal and perceptual processing abnormalities, identified in a number of electrophysiological and brain imaging studies of individuals with (ASD), are likely to impact on speech perception, surprisingly little is known about the behavioral outcomes of such abnormalities. It has been hypothesized that rapid temporal processing deficits may be linked to impaired language development through interference with acoustic information during speech perception. The present study aimed to investigate the impact of temporal changes on encoding and recall of speech, and the associated cognitive, clinical, and behavioral correlates in adults with ASD. Research carried out with typically developing (TD) adults has shown that word recall diminishes as the speed of speech increases, and it was predicted that the magnitude of this effect would be far greater in those with ASD because of a preexisting rapid temporal processing deficit. Nineteen high‐functioning adults with ASD, and age‐ and intelligence‐matched TD controls performed verbatim recall of temporally manipulated sentences. Reduced levels of word recall in response to increases in presentation speed were observed, and this effect was greater in the older participants in the ASD group than in the control group. This is the first study to show that both sensory abnormalities and aging impact on speech encoding in ASD. Auditory processing deficits in ASD may be indicative of an association with the sensory abnormalities and social and communication impairments characterizing the disorder. Autism Res 2014, 7: 40–49. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.
Hochfester Beton in Gleitschalung.
Authors: Maliha R. , Hilsdorf H. K.
Published: October 2013

In einem Forschungsvorhaben werden die Möglichkeiten der Herstellung von hochfestem Beton in Gleitschalbauweise untersucht. Es werden Schalungsreibung, Verschleißwiderstand und Mikrorißbildung an der Oberfläche in Gleitversuchen bestimmt.
Durchstanzbemessung von Doppelkopfankern nach Europäischen Technischen Zulassungen
Authors: Lindorf Alexander
Published: October 2013

Die Einführung des EC2 im Stahlbetonhochbau führte zu einer umfangreichen Umstellung der bisherigen Regeln zur Bemessung gegen Durchstanzen. Betroffen sind davon vor allem auch die Bewehrungsformen mit Doppelkopfankern. Die Verwendung dieser speziellen Durchstanzbewehrungen wurde in Deutschland bislang über allgemeine bauaufsichtliche Zulassungen geregelt. Die Nachweisführung erfolgte in Anlehnung an DIN 1045‐1. Um nunmehr dem Bemessungskonzept des EC2 gerecht zu werden, waren neue Zulassungsdokumente erforderlich, welche mittlerweile in Form von Europäischen Technischen Zulassungen erteilt wurden. Allerdings weicht die darin festgeschriebene Bemessung von Doppelkopfankern in einigen wichtigen Punkten vom EC2 ab. In diesem Beitrag wird ein Überblick über die einzelnen Regelungen und deren Hintergründe gegeben. Ein Bemessungsbeispiel demonstriert den allgemeinen Bemessungsablauf.

Punching shear design of double‐headed anchors according to European Technical Approvals

The introduction of EC2 in structural engineering led to an extensive transformation of the existing guidelines for the design against punching shear failure. Especially reinforcement types consisting of double‐headed anchors are affected. In Germany, the use of these special punching shear reinforcements was previously regulated by national approvals. The verification procedure was carried out according to DIN 1045‐1. In order to satisfy the design concept according to EC2, new approval documents were required. Meanwhile European Technical Approvals were issued. However, in some important aspects the specified design method of double‐headed anchors differs from EC2. The paper gives an overview of the various rules and their backgrounds. A design example demonstrates the general design process.
Toggling a conformational switch in Wnt/β‐catenin signaling: Regulation of Axin phosphorylation
Authors: Tacchelly‐Benites Ofelia , Wang Zhenghan , Yang Eungi , Lee Ethan , Ahmed Yashi
Published: October 2013

The precise orchestration of two opposing protein complexes – one in the cytoplasm (β‐catenin destruction complex) and the other at the plasma membrane (LRP6 signaling complex) – is critical for controlling levels of the transcriptional co‐factor β‐catenin, and subsequent activation of the Wnt/β‐catenin signal transduction pathway. The Wnt pathway component Axin acts as an essential scaffold for the assembly of both complexes. How the β‐catenin destruction and LRP6 signaling complexes are modulated following Wnt stimulation remains controversial. A recent study in Science by He and coworkers reveals an underlying logic for Wnt pathway control in which Axin phosphorylation toggles a switch between the active and inactive states. This mini‐review focuses on this and two other recent studies that provide insight into the initial signaling events triggered by Wnt exposure. We emphasize regulation of the β‐catenin destruction and LRP6 signaling complexes and propose a framework for future work in this area.
Spider silks from plants – a challenge to create native‐sized spidroins
Authors: Hauptmann Valeska , Weichert Nicola , Rakhimova Marziya , Conrad Udo
Published: October 2013

Silk threads from spiders exhibit extraordinary mechanical properties, such as superior toughness and elasticity. Spider silks consist of several different large repetitive proteins that act as the basic materials responsible for these outstanding features. The production of spider silk protein variants in plants opens up new horizons in the production and functional investigation that enable the use of spider silks in innovative material development, nanotechnology and biomedicine in the future. This review summarizes and discusses production of spider silk protein variants in plants, especially with regards to plant expression systems, purification strategies, and characteristics of spider silk variants. Furthermore, the challenge of producing native‐sized recombinant spidroins in planta is outlined, presenting three different strategies for achieving these high repetitive proteins with the help of non‐repetitive C‐terminal domains, crosslinking transglutaminase, and self‐linking inteins. The potential of these fascinating proteins in medicine is also highlighted.
Fluorogenic small molecules requiring reaction with a specific protein to create a fluorescent conjugate for biological imaging–what we know and what we need to learn
Authors: Baranczak Aleksandra , Connelly Stephen , Liu Yu , Choi Sungwook , Grimster Neil P. , Powers Evan T. , Wilson Ian A. , Kelly Jeffery W.
Published: October 2013

We seek fluorogenic small molecules that generate a fluorescent conjugate signal if and only if they react with a given protein‐of‐interest (i.e., small molecules for which noncovalent binding to the protein‐of‐interest is insufficient to generate fluorescence). Consequently, it is the new chemical entity afforded by the generally irreversible reaction between the small molecule and the protein‐of‐interest that enables the energy of an electron occupying the lowest unoccupied molecular orbital (LUMO) of the chromophore to be given off as a photon instead of being dissipated by nonradiative mechanisms in complex biological environments. This category of fluorogenic small molecules is created by starting with environmentally sensitive fluorophores that are modified by an essential functional group that efficiently quenches the fluorescence until a chemoselective reaction between that functional group and the protein‐of‐interest occurs, yielding the fluorescent conjugate. Fluorogenic small molecules are envisioned to be useful for a wide variety of applications, including live cell imaging without the requirement for washing steps and pulse‐chase kinetic analyses of protein synthesis, trafficking, degradation, etc. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 484–495, 2014.
Cycloartanes from the Gum Resin of Gardenia gummifera L.f.
Authors: Gandhe Sreekanth , Lakavath Suryanarayana , Palatheeya Sujatha , Schuehly Wolfgang , Amancha Kalpana , Kiran Reddy Nallamaddi Ravi , Palepu Anupama , Thakur Yogita , Rao Adavi Rao Belvotagi Venkat , Kumar Bobbala Ravi , Narasimha Appa Rao Achanta Venkata , Kunert Olaf
Published: October 2013

The gum resin exuding from the leaf buds of Gardenia gummifera was investigated. Eight new cycloartane triterpenes, 1–6, 8, and 10, together with two known triterpenes, 25‐hydroxycycloart‐23‐en‐3‐one (7) and cycloartenone (9), were isolated and identified by extensive NMR spectroscopy. For cycloartenone (9), full NMR assignments are given as these data were not available in the literature. Eight compounds possess a C(3)O group, two are 3,4‐secocycloartanes bearing a free C(3)OOH group; in one of the cycloartanes, gummiferartane‐9 (10), ring A occurs as a seven‐membered lactone.
The Volatile Profiles of a Rare Apple (Malus domesticaBorkh.) Honey: Shikimic Acid‐Pathway Derivatives, Terpenes, and Others
Authors: Kuś Piotr Marek , Jerković Igor , Tuberoso Carlo Ignazio Giovanni , Šarolić Mladenka
Published: October 2013

The volatile profiles of rare Malus domestica Borkh. honey were investigated for the first time. Two representative samples from Poland (sample I) and Spain (sample II) were selected by pollen analysis (44–45% of Malus spp. pollen) and investigated by GC/FID/MS after headspace solid‐phase microextraction (HS‐SPME) and ultrasonic solvent extraction (USE). The apple honey is characterized by high percentage of shikimic acid‐pathway derivatives, as well as terpenes, norisoprenoids, and some other compounds such as coumaran and methyl 1H‐indole‐3‐acetate. The main compounds of the honey headspace were (sample I; sample II): benzaldehyde (9.4%; 32.1%), benzyl alcohol (0.3%; 14.4%), hotrienol (26.0%, 6.2%), and lilac aldehyde isomers (26.3%; 1.7%), but only Spanish sample contained car‐2‐en‐4‐one (10.2%). CH2Cl2 and pentane/Et2O 1 : 2 (v/v) were used for USE. The most relevant compounds identified in the extracts were: benzaldehyde (0.9–3.9%), benzoic acid (2.0–11.2%), terpendiol I (0.3–7.4%), coumaran (0.0–2.8%), 2‐phenylacetic acid (2.0–26.4%), methyl syringate (3.9–13.1%), vomifoliol (5.0–31.8%), and methyl 1H‐indole‐3‐acetate (1.9–10.2%). Apple honey contained also benzyl alcohol, 2‐phenylethanol, (E)‐cinnamaldehyde, (E)‐cinnamyl alcohol, eugenol, vanillin, and linalool that have been found previously in apple flowers, thus disclosing similarity of both volatile profiles.
Chemical Composition of Essential Oils and Aromatic Waters from Different Italian Anthemis maritima Populations
Authors: Ciccarelli Daniela , Noccioli Cecilia , Pistelli Luisa
Published: October 2013

The chemical composition of the essential oils and aromatic waters isolated from six Italian Anthemis maritima populations was determined by GC‐FID and GC/MS analyses. In total, 122 and 100 chemical compounds were identified in the essential oils and the aromatic waters, respectively. The main compound classes represented in the oils were monoterpene hydrocarbons, oxygenated monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes, and terpene esters. Multivariate chemometric techniques such as cluster analysis (CA) and principal coordinate analysis (PCO) were used to classify the samples according to the geographical origin. Statistical analysis allowed the attribution of the analyzed populations to different chemotype groups.
The effects of artemisinin on the proliferation and apoptosis of vascular smooth muscle cells of rats
Authors: Wang Hai‐yang , Huang Ren‐ping , Han Peng , Xue Dong‐bo , Li Hai‐bin , Liu Bing , Shan Peng , Wang Qing‐shan , Li Ke‐shen , Li Ha‐li
Published: October 2013

Objective

The aim of this study was to evaluate the effect of artemisinin on the proliferation and apoptosis of rat vascular smooth muscle cells (VSMCs).

Method

Primary rat VSMCs were treated with various doses of artemisinin. Cell proliferation was evaluated by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, and the messenger RNA and protein expressions of proliferating cell nuclear antigen were determined by reverse‐transcription polymerase chain reaction and immunohistochemistry. Apoptosis was measured using annexin V and propidium iodide double staining evaluated by flow cytometry. Protein expression of Bax, Bcl2, and cyclin‐dependent kinase 4 was determined by Western blot.

Results

After 72 h of treatment, artemisinin significantly inhibited VSMC proliferation in a dose‐dependent manner. Treatment with 1 mM artemisinin for 72 h significantly reduced the expression of proliferating cell nuclear antigen messenger RNA. On the other hand, the same treatment increased the apoptosis of VSMCs, the activation of caspase‐3, the Bax protein expression, and the Bax/Bcl2 ratio.

Conclusion

The results suggest that artemisinin can effectively inhibit VSMC proliferation and induce VSMC apoptosis. Copyright © 2013 John Wiley & Sons, Ltd.
Direct Energy Extraction from Brown Macroalgae‐Derived Alginate by Gold Nanoparticles on Functionalized Carbon Nanotubes
Authors: Hoa Le Quynh , Yoshikawa Hiroyuki , Saito Masato , Ueda Mitsuyoshi , Shibata Toshiyuki , Tamiya Eiichi
Published: October 2013

The viability of employing brown macroalgae as a future renewable energy and chemical resource has so far proven to be challenging because of the low efficiency of the energy extraction process from alginate, which forms the principle, difficult‐to‐degrade component. In contrast to currently employed alginate‐metabolizing microbial approaches, we here extract energy from macroalgae, for the first time, through a fuel cell system that exploits the electrochemical oxidation of alginate by gold nanoparticle‐decorated functionalized carbon nanotubes without any external input of energy. The analyses suggest that the electrochemical oxidation process induces partial oxidation of alginate and, in addition to bioenergy, also yields valuable chemicals, which paves the way for the future production of energy and feedstock materials from inedible biomass.
Platinum Ruthenium Catalysts Supported on Carbon Xerogel for Methanol Electro‐Oxidation: Influence of the Catalyst Synthesis Method
Authors: Alegre Cinthia , Gálvez María Elena , Moliner Rafael , Baglio Vincenzo , Stassi Alessandro , Aricò Antonino Salvatore , Lázaro María Jesús
Published: October 2013

A high surface area, highly mesoporous carbon xerogel was synthesised and used as a support in the preparation of platinum–ruthenium catalysts by different synthetic routes. The platinum–ruthenium carbon xerogel catalysts were physico‐chemically characterised and used for the chemical electro‐oxidation of methanol. The synthetic routes pursued included: 1) impregnation with metal chloride precursors and reduction with two different reducing agents: sodium borohydride and formic acid; 2) a microemulsion‐based method and 3) a sulfite complex method, which led to catalysts with different physico‐chemical features that strongly influence their catalytic behaviour towards methanol oxidation. The electro‐oxidation of methanol was found to depend on both the crystal size and the extent of active phase reduction as well as on the platinum concentration on the catalyst surface, which were maximised for the impregnation method and reduction with formic acid.
Acid‐Activated Carbon Materials: Cheaper Alternative Catalysts for the Synthesis of Substituted Quinolines
Authors: López‐Sanz Jesús , Pérez‐Mayoral Elena , Soriano Elena , Omenat‐Morán Delia , Durán Carlos J. , Martín‐Aranda Rosa María , Matos Ines , Fonseca Isabel
Published: October 2013

We describe the first examples of Friedländer reactions efficiently catalyzed by carbon materials. We report herein a series of acidic activated carbon materials, which can be considered as an environmentally friendly, cheaper alternative to the traditional acidic mesoporous silicates or even zeolites for the synthesis of quinolines/quinolones. Textural parameters of the acidic activated carbon materials together with their acidic properties are important factors that affect the reaction selectivity. Some mechanistic details have been addressed by computational calculations.
Conformational Analysis of the Anti‐obesity Drug Lorcaserin in Water: How To Take Advantage of Long‐Range Residual Dipolar Couplings
Authors: Trigo‐Mouriño Pablo , de la Fuente M. Carmen , Gil Roberto R. , Sánchez‐Pedregal Víctor M. , Navarro‐Vázquez Armando
Published: October 2013

The conformational state of 8‐chloro‐1‐methyl‐2,3,4,5‐tetrahydro‐1H‐3‐benzazepine hydrochloride (lorcaserin) in water has been determined on the basis of one‐bond and long‐range CH residual dipolar coupling (RDC) data along with DFT computations and 3JHH coupling‐constant analysis. According to this analysis, lorcaserin exists as a conformational equilibrium of two crown‐chair forms, of which the preferred conformation has the methyl group in an equatorial orientation.
Structure–Property Relationships and 1O2 Photosensitisation in Sterically Encumbered Diimine PtII Acetylide Complexes
Authors: Nolan Deanne , Gil Belén , Wang Longsheng , Zhao Jianzhang , Draper Sylvia M.
Published: October 2013

A series of sterically encumbered [Pt(L)(σ‐acetylide)2] complexes were prepared in which L, a dendritic polyaromatic diimine ligand, was held constant (L=1‐(2,2′‐bipyrid‐6‐yl)‐2,3,4,5‐tetrakis(4‐tert‐butylphenyl)benzene) and the cis ethynyl co‐ligands were varied. The optical properties of the complexes were tuned by changing the electronic character, extent of π conjugation and steric bulk of the ethynyl ligands. Replacing electron‐withdrawing phenyl‐CF3 substituents (4) with electron‐donating pyrenes (5) resulted in a red shift of both the lowest‐energy absorption (ΔE=3300 cm−1, 61 nm) and emission bands (ΔE=1930 cm−1, 64 nm). The emission, assigned in each case as phosphorescence on the basis of the excited‐state lifetimes, switched from being 3MMLL′CT‐derived (mixed metal–ligand‐to‐ligand charge transfer) when phenyl/polyphenylene substituents (3, 4, 6) were present, to ligand‐centred 3ππ* when the substituents were more conjugated aromatic platforms [pyrene (5) or hexa‐peri‐hexabenzocoronene (7)]. The novel PtII acetylide complexes 5 and 7 absorb strongly in the visible region of the electromagnetic spectrum, which along with their long triplet excited‐state lifetimes suggested they would be good candidates for use as singlet‐oxygen photosensitisers. Determined by in situ photooxidation of 1,5‐dihydroxynaphthalene (DHN), the photooxidation rate with pyrenyl‐5 as sensitiser (kobs=39.3×10−3 min−1) was over half that of the known 1O2 sensitiser tetraphenylporphyrin (kobs=78.6×10−3 min−1) under the same conditions. Measured 1O2 quantum yields of complexes 5 and 7 were half and one‐third, respectively, of that of TPP, and thus reveal an efficient triplet–triplet energy‐transfer process in both cases.
Conformational Selection in Glycomimetics: Human Galectin‐1 Only Recognizes syn‐Ψ‐Type Conformations of β‐1,3‐Linked Lactose and Its C‐Glycosyl Derivative
Authors: Vidal Paloma , Roldós Virginia , Fernández‐Alonso María del Carmen , Vauzeilles Boris , Bleriot Yves , Cañada F. Javier , André Sabine , Gabius Hans‐Joachim , Jiménez‐Barbero Jesús , Espinosa Juan Félix , Martín‐Santamaría Sonsoles
Published: October 2013

The human lectin galectin‐1 (hGal‐1) translates sugar signals, that is, β‐galactosides, into effects on the level of cells, for example, growth regulation, and has become a model for studying binding of biopharmaceutically relevant derivatives. Bound‐state conformations of Galβ‐C‐(1→3)‐Glcβ‐OMe (1) and its βGal‐(1→3)‐βGlc‐OMe disaccharide parent compound were studied by using NMR spectroscopy (transferred (TR)‐NOESY data), assisted by docking experiments and molecular dynamics (MD) simulations. The molecular recognition process involves a conformational selection event. Although free C‐glycoside access four distinct conformers in solution, hGal‐1 recognizes shape of a local minimum of compound 1, the syn‐Φ/syn‐Ψ conformer, not the structure at global minimum. MD simulations were run to explain, in structural terms, the observed geometry of the complex.
Fe‐Catalyzed One‐Pot Oxidative Cleavage of Unsaturated Fatty Acids into Aldehydes with Hydrogen Peroxide and Sodium Periodate
Authors: Spannring Peter , Yazerski Vital , Bruijnincx Pieter C. A. , Weckhuysen Bert M. , Klein Gebbink Robertus J. M.
Published: October 2013

A one‐pot method has been developed for the oxidative cleavage of internal alkenes into aldehydes by using 0.5 mol % of the nonheme iron complex [Fe(OTf)2(mix‐bpbp)] (bpbp=N,N′‐bis(2‐picolyl)‐2,2′‐bipyrrolidine) as catalyst and 1.5 equivalents of hydrogen peroxide and 1 equivalent of sodium periodate as oxidants. A mixture of diastereomers of the chiral bpbp ligand can be used, thereby omitting the need for resolution of its optically active components. The cleavage reaction can be performed in one pot within 20 h and under ambient conditions. Addition of water after the epoxidation, acidification and subsequent pH neutralization are crucial to perform the epoxidation, hydrolysis, and subsequent diol cleavage in one pot. High aldehyde yields can be obtained for the cleavage of internal aliphatic double bonds with cis and trans configuration (86–98 %) and unsaturated fatty acids and esters (69–96 %). Good aldehyde yields are obtained in reactions of trisubstituted and terminal alkenes (62–63 %). The products can be easily isolated by a simple extraction step with an organic solvent. The presented protocol involves a lower catalyst loading than conventional methods based on Ru or Os. Also, hydrogen peroxide can be used as the oxidant in this case, which is often disproportionated by second‐ and third‐row metals. By using only mild oxidants, overoxidation of the aldehyde to the carboxylic acid is prevented.
The Isolation of Single MMX Chains from Solution: Unravelling the Assembly–Disassembly Process
Authors: Azani Mohammad‐Reza , Paz Alejandro Pérez , Hermosa Cristina , Givaja Gonzalo , Gómez‐Herrero Julio , Mas‐Ballesté Rubén , Zamora Felix , Rubio Angel
Published: October 2013

Herein, we provide a systematic theoretical and experimental study of the structural and optical properties of MMX (M=metal, X=halide) chains. The influence of solvent, temperature, and concentration has been analyzed to find suitable parameters for initial building‐block associations in solution. By using density functional calculations, we have computed the dissociation energy of different MMX oligomers (up to the tetramer) in the gas phase. On the basis of these findings, we discuss the most likely disassembly scenario and propose a new interpretation of these compounds. We also calculated the charge redistribution that occurs upon MM+XMMX binding in vacuum. Time‐dependent density functional theory (TDDFT) is used to calculate the UV/visible spectra of different MMX chains up to the tetramer in the gas phase. The implications of these theoretical findings in the analysis of our experiments are discussed in the text. The overall body of data presented suggests a new way of looking at such linear structures. By taking into account these new data, we have been able to isolate single/few MMX chains on mica.
Lyotropic Liquid Crystal to Soft Mesocrystal Transformation in Hydrated Salt–Surfactant Mixtures
Authors: Albayrak Cemal , Barım Gözde , Dag Ömer
Published: October 2013

Hydrated CaCl2, LiI, and MgCl2 salts induce self‐assembly in nonionic surfactants (such as C12H25(OCH2CH2)10OH) to form lyotropic liquid‐crystalline (LLC) mesophases that undergo a phase transition to a new type of soft mesocrystal (SMC) under ambient conditions. The SMC samples can be obtained by aging the LLC samples, which were prepared as thin films by spin‐coating, dip‐coating, or drop‐casting of a clear homogenized solution of water, salt, and surfactant over a substrate surface. The LLC mesophase exists up to a salt/surfactant mole ratio of 8, 10, and 4 (corresponding to 59, 68, and 40 wt % salt/surfactant) in the CaCl2, LiI, and MgCl2 mesophases, respectively. The SMC phase can transform back to a LLC mesophase at a higher relative humidity. The phase transformations have been monitored using powder X‐ray diffraction (PXRD), polarized optical microscopy (POM), and FTIR techniques. The LLC mesophases only diffract at small angles, but the SMCs diffract at both small and wide angles. The broad surfactant features in the FTIR spectra of the LLC mesophases become sharp and well resolved upon SMC formation. The unit cell of the mesophases expands upon SMC transformation, in which the expansion is largest in the MgCl2 and smallest in the CaCl2 systems. The POM images of the SMCs display birefringent textures with well‐defined edges, similar to crystals. However, the surface of the crystals is highly patterned, like buckling patterns, which indicates that these crystals are quite soft. This unusual phase behavior could be beneficial in designing new soft materials in the fields of phase‐changing materials and mesostructured materials, and it demonstrates the richness of the phase behavior in the salt–surfactant mesophases.
New Reactions of N‐tert‐Butylimines; Formation of N‐Heterocycles by Methyl Radical Elimination on Flash Vacuum Thermolysis of N‐Benzylidene‐ and N‐(2‐Pyridylmethylidene)‐tert‐butylamines
Authors: Vu Thien Y , Chrostowska Anna , Huynh Thi Kieu Xuan , Khayar Saïd , Dargelos Alain , Justyna Katarzyna , Pasternak Beata , Leśniak Stanisław , Wentrup Curt
Published: October 2013

Thermal reactions of N‐benzylidene‐ and N‐(2‐pyridylmethylidene)‐tert‐butylamines (5 and 13) under FVT conditions have been investigated. Unexpectedly, at 800 °C, compound 5 yields 1,2‐dimethylindole and 3‐methylisoquinoline. In the reaction of 13 at 800 °C, 3‐methylimidazo[1,5‐a]pyridine was obtained as the major product. Mechanisms of these reactions have been proposed on the basis of DFT calculations. Furthermore, UV‐photoelectron spectroscopy combined with FVT has been applied for direct monitoring and characterization of the thermolysis products in situ.
Conformational Diversity in Contryphans from Conus Venom: cis–trans Isomerisation and Aromatic/Proline Interactions in the 23‐Membered Ring of a 7‐Residue Peptide Disulfide Loop
Authors: Sonti Rajesh , Gowd Konkallu Hanumae , Rao K. N. Shashanka , Ragothama Srinivasarao , Rodriguez Alex , Perez Juan Jesus , Balaram Padmanabhan
Published: October 2013

Conformational diversity or “shapeshifting” in cyclic peptide natural products can, in principle, confer a single molecular entity with the property of binding to multiple receptors. Conformational equilibria have been probed in the contryphans, which are peptides derived from Conus venom possessing a 23‐membered cyclic disulfide moiety. The natural sequences derived from Conus inscriptus, GCVDLYPWC* (In936) and Conus loroisii, GCPDWDPWC* (Lo959) differ in the number of proline residues within the macrocyclic ring. Structural characterisation of distinct conformational states arising from cis–trans equilibria about Xxx–Pro bonds is reported. Isomerisation about the C2–P3 bond is observed in the case of Lo959 and about the Y5–P6 bond in In936. Evidence is presented for as many as four distinct species in the case of the synthetic analogue V3P In936. The Tyr‐Pro‐Trp segment in In936 is characterised by distinct sidechain orientations as a consequence of aromatic/proline interactions as evidenced by specific sidechain–sidechain nuclear Overhauser effects and ring current shifted proton chemical shifts. Molecular dynamics simulations suggest that Tyr5 and Trp7 sidechain conformations are correlated and depend on the geometry of the Xxx–Pro bond. Thermodynamic parameters are derived for the cis↔ trans equilibrium for In936. Studies on synthetic analogues provide insights into the role of sequence effects in modulating isomerisation about Xxx–Pro bonds.
A Theoretical DFT‐Based and Experimental Study of the Transmetalation Step in Au/Pd‐Mediated Cross‐Coupling Reactions
Authors: Hansmann Max M. , Pernpointner Markus , Döpp René , Hashmi A. Stephen K.
Published: October 2013

In this work a combined theoretical and experimental investigation of the cross‐coupling reaction involving two metallic reaction centers, namely gold and palladium, is described. One metal center (Au) hereby is rather inert towards change in its oxidation state, whereas Pd undergoes oxidative insertion and reductive elimination steps. Detailed mechanistic and energetic studies of each individual step, with the focus on the key transmetalation step are presented and compared for different substrates and ligands on the catalytic Pd center. Different aryl halides (Cl, Br, I) and aryl triflates were investigated. Hereby the nature of the counteranion X turned out to be crucial. In the case of X=Cl and L=PMe3 the oxidative addition is rate‐determining, whereas in the case of X=I the transmetalation step becomes rate‐determining in the Au/Pd‐cross‐coupling mechanism. A variety of Au–Pd transmetalation reaction scenarios are discussed in detail, favoring a transition state with short intermetallic Au–Pd contacts. Furthermore, without a halide counteranion the transmetalation from gold(I) to palladium(II) is highly endothermic, which confirms our experimental findings that the coupling does not occur with aryl triflates and similar weakly coordinating counteranions—a conclusion that is essential in designing new Au–Pd catalytic cycles. In combination with experimental work, this corrects a previous report in the literature claiming a successful coupling potentially catalytic in both metals with weakly coordinating counteranions.
Design of Glycosyltransferase Inhibitors: Pyridine as a Pyrophosphate Surrogate
Authors: Wang Shuai , Cuesta‐Seijo Jose A. , Lafont Dominique , Palcic Monica M. , Vidal Sébastien
Published: October 2013

A series of ten glycosyltransferase inhibitors has been designed and synthesized by using pyridine as a pyrophosphate surrogate. The series was prepared by conjugation of carbohydrate, pyridine, and nucleoside building blocks by using a combination of glycosylation, the Staudinger–Vilarrasa amide‐bond formation, and azide–alkyne click chemistry. The compounds were evaluated as inhibitors of five metal‐dependent galactosyltransferases. Crystallographic analyses of three inhibitors complexed in the active site of one of the enzymes confirmed that the pyridine moiety chelates the Mn2+ ion causing a slight displacement (2 Å) from its original position. The carbohydrate head group occupies a different position than in the natural uridine diphosphate (UDP)–Gal substrate with little interaction with the enzyme.
Fluorescent Protein Capped Mesoporous Nanoparticles for Intracellular Drug Delivery and Imaging
Authors: Yang Xinjian , Li Zhenhua , Li Meng , Ren Jinsong , Qu Xiaogang
Published: October 2013

A multifunctional system for intracellular drug delivery and simultaneous fluorescent imaging was constructed by using histidine‐tagged, cyan fluorescent protein (CFP)‐capped magnetic mesoporous silica nanoparticles (MMSNs). This protein‐capped multifunctional nanostructure is highly biocompatible and does not affect cell viability or proliferation. The CFP acts not only as a capping agent, but also as a fluorescent imaging agent. The nanoassembly was activated by histidine‐based replacement, leading to release of drug molecules encapsulated in the nanopores into the bulk solution. The fluorescent imaging functionality would allow noninvasive tracking of the nanoparticles in the body. By combining the drug delivery with cell‐imaging capability, these nanoparticles may provide valuable multifunctional nanoplatforms for biomedical applications.
Pyridine‐Enhanced Head‐to‐Tail Dimerization of Terminal Alkynes by a Rhodium–N‐Heterocyclic‐Carbene Catalyst
Authors: Rubio‐Pérez Laura , Azpíroz Ramón , Di Giuseppe Andrea , Polo Victor , Castarlenas Ricardo , Pérez‐Torrente Jesús J. , Oro Luis A.
Published: October 2013

A general regioselective rhodium‐catalyzed head‐to‐tail dimerization of terminal alkynes is presented. The presence of a pyridine ligand (py) in a Rh–N‐heterocyclic‐carbene (NHC) catalytic system not only dramatically switches the chemoselectivity from alkyne cyclotrimerization to dimerization but also enhances the catalytic activity. Several intermediates have been detected in the catalytic process, including the π‐alkyne‐coordinated RhI species [RhCl(NHC)(η2‐HCCCH2Ph)(py)] (3) and [RhCl(NHC){η2‐C(tBu)C(E)CHCHtBu}(py)] (4) and the RhIII–hydride–alkynyl species [RhClH{CCSi(Me)3}(IPr)(py)2] (5). Computational DFT studies reveal an operational mechanism consisting of sequential alkyne CH oxidative addition, alkyne insertion, and reductive elimination. A 2,1‐hydrometalation of the alkyne is the more favorable pathway in accordance with a head‐to‐tail selectivity.
Thiepin‐Fused Heteroacenes: Simple Synthesis, Unusual Structure, and Semiconductors with Less Anisotropic Behavior
Authors: Cai Zhengxu , Zhang Hantang , Geng Hua , Liu Zitong , Yang Sifen , Luo Hewei , Jiang Lang , Peng Qian , Zhang Guanxin , Chen Jianming , Yi Yuanping , Hu Wenping , Zhang Deqing
Published: October 2013

The simple one‐pot syntheses of sulfur‐rich thiepin‐fused heteroacences with an alkylidene–fluorene framework, THA1 and THA6 (thiepin‐fused heteroacene 1 or 6, in which the thiepin is conjugated at both ortho positions with SCH3 or SC6H13, respectively), is reported. Based on electrochemical studies and theoretical calculations, their LUMO energies are relatively low (−3.26 eV), and their HOMO and HOMO−1 orbitals are nearly degenerate. The thiepin ring contributes mainly to HOMO−1 and LUMO orbitals, however, HOMO orbitals dominantly reside on thienoacence rings. Within the crystal of THA1, the molecules adopt a herringbone arrangement and multiple intermolecular interactions lead to the formation of a 2D network. Interestingly, THA6 shows totally different intermolecular arrangements. Organic field‐effect transistor (OFET) devices show both compounds exhibiting p‐type semiconducting behavior. Thin films or microcrystals of THA1 possess relatively high hole mobility. Moreover, the mobilities of the microcrystal of THA1 along three directions are in the same order, thus the hole‐carrier transporting within the hexagonal‐plane of microcrystal of THA1 exhibits less anisotropic behavior. In comparison, both thin films and microrods of THA6 show low hole mobilities. This agrees well with the intermolecular arrangements and interactions within crystal of THA6. Further theoretical calculations reveal that significant intermolecular electronic coupling among HOMO−1 orbitals and sulfur atoms play an important role in intermolecular electronic coupling for THA1.
Linear and Cyclic Hybrids of Alternating Thiophene–Amino Acid Units: Synthesis and Effects of Chirality on Conformation and Molecular Packing
Authors: Ngo Thien H. , Berndt Hülya , Wilsdorf Michael , Lentz Dieter , Reissig Hans‐Ulrich
Published: October 2013

The dipeptide isostere 5‐aminothiophene carboxylic acid has been combined with L‐phenylalanine moieties to provide linear and cyclic hybrid oligopeptides. A suitable protecting group strategy and appropriate coupling methods have been developed to guarantee a high degree of enantiopurity of the resulting amides. Cyclic tetraamides have been efficiently obtained by macrocyclization of the linear derivatives. In the case of racemized cyclization precursors, two diastereomeric macrocycles (S,S/R,R and meso) have been isolated. Their crystal structures show clear effects of the stereogenic centers on the ring conformations and molecular packing.
Highly Efficient Deep‐Blue Emitters Based on cis and trans N‐Heterocyclic Carbene PtII Acetylide Complexes: Synthesis, Photophysical Properties, and Mechanistic Studies
Authors: Zhang Yuzhen , Blacque Olivier , Venkatesan Koushik
Published: October 2013

We have synthesized cis and trans N‐heterocyclic carbene (NHC) platinum(II) complexes bearing σ‐alkynyl ancillary ligands, namely [Pt(dbim)2(CCR)2] [DBIM=N,N′‐didodecylbenzimidazoline‐2‐ylidene; R=C6H4F (4), C6H5 (5), C6H2(OMe)3 (6), C4H3S (7), and C6H4CCC6H5 (8)] and [Pt(ibim)2(CCC6H5)2] (9) (ibim=N,N′‐diisopropylbenzimidazoline‐2‐ylidene), starting from [Pt(cod)(CCR)2] (COD=cyclooctadiene) and 2 equivalents of [dbimH]Br ([ibimH]Br for complexes 9) in the presence of tBuOK and THF. Mechanistic investigations aimed at uncovering the cis to trans isomerization reaction have been performed on the representative cis complex 5 a [Pt(dbim)2(CCC6H5)2] and revealed the isomerization to progress smoothly in good yield when 5 a was treated with catalytic amounts of [Pt(cod)(CCR)2] at 75 °C in THF or when 5 a was heated at 200 °C in the solid state under an inert atmosphere. Detailed examination of the reactions points to the possible involvement, in a catalytic fashion, of a solvent‐stabilized PtII dialkyne complex in the former case and a Pt0 NHC complex in the latter case, for the transformation of the cis isomer to the corresponding trans complex. Thermal stability and the isomerization process in the solid state have been further investigated on the basis of TGA and DSC measurements. X‐ray diffraction studies have been carried out to confirm the solid‐state structures of 4 b, 5 a, 5 b, and 9 b. All of the synthesized dialkyne complexes 4–9 exhibit phosphorescence in solution, in the solid state at room temperature (RT), and also in frozen solvent glasses at 77 K. The emission wavelengths and quantum yields have been found to be highly tunable as a function of the alkynyl ligand. In particular, the trans isomer of complex 9 in a spin‐coated film (10 wt % in poly(methyl methacrylate), PMMA) exhibits a high phosphorescence quantum yield of 80 %, which is the highest reported for PtII‐based deep‐blue emitters. Experimental observations and time‐dependent density functional theory (TD‐DFT) calculations are strongly indicative of the emission being mainly governed by metal‐perturbed interligand (3IL) charge transfer.
Synthesis of an Orthogonal Topological Analogue of Helicene
Authors: Wixe Torbjörn , Wallentin Carl‐Johan , Johnson Magnus T. , Fristrup Peter , Lidin Sven , Wärnmark Kenneth
Published: October 2013

The synthesis of an orthogonal topological pentamer analogue of helicene is presented. This analogue forms a tubular structure with its aromatic systems directed parallel to the axis of propagation, which creates a cavity with the potential to function as a host molecule. The synthetic strategy reported, based on a series of repeating Friedländer condensations that utilize pyrido[3,2‐d]pyrimidine moieties as protected amino aldehydes, allows for the facile access of higher generations of helical, tubular structures. As a result of the synthetic strategy, only a helical isomer of the pentamer is possible. The structure and absolute configuration of the pentamer were elucidated from a combination of NMR spectroscopic data, optical properties, X‐ray structures, and by comparison of an experimental electronic circular dichroism spectrum to a calculated spectrum.