bluuebunny/crossref_metadata_2025_split huggingface dataset:
Upward Trend in Catalytic Efficiency of Rare‐Earth Triflate Catalysts in Friedel–Crafts Aromatic Sulfonylation Reactions
Authors: Nguyen Vo Thu An , Duus Fritz , Le Thach Ngoc 
Published: July 2014

AbstractA series of 14 lanthanide (Ln) triflates were investigated as sustainable catalysts for aromatic sulfonylation reactions under microwave irradiation. The catalytic efficiency of the early triflates La(OTf)3–Eu(OTf)3 is good for long irradiation times. For the later lanthanides, yields reaching over 90 % were achieved for short irradiation periods. This was the case especially for Tm(OTf)3, Yb(OTf)3, and Lu(OTf)3, of which Yb(OTf)3 was the most efficient. The upward trend in catalytic efficiency therefore correlates with the lanthanide sequence in the periodic table. The results can be explained by the decrease in the radii of the Ln3+ ions, and the hydrolysis and water‐exchanges rate within the series. The results are in agreement with the first principal property value (t1) calculated by principal component analysis (PCA) published previously. A large drop in sulfonylation yield was obtained with Gd(OTf)3, which matched the “gadolinium break”; the well‐known discontinuity in lanthanide properties.
Coordination‐Driven In Situ Self‐Assembly Strategy for the Preparation of Metal–Organic Framework Hybrid Membranes
Authors: Zhang Rong , Ji Shulan , Wang Naixin , Wang Lin , Zhang Guojun , Li Jian‐Rong 
Published: July 2014

AbstractMetal–organic frameworks (MOFs) have emerged as porous solids of a superior type for the fabrication of membranes. However, it is still challenging to prepare a uniformly dispersed robust MOF hybrid membrane. Herein, we propose a simple and powerful strategy, namely, coordination‐driven in situ self‐assembly, for the fabrication of MOF hybrid membranes. On the basis of the coordination interactions between metal ions and ligands and/or the functional groups of the organic polymer, this method was confirmed to be feasible for the production of a stable membrane with greatly improved MOF‐particle dispersion in and compatibility with the polymer, thus providing outstanding separation ability. As an experimental proof of concept, a high‐quality ZIF‐8/PSS membrane was fabricated that showed excellent performance in the nanofiltration and separation of dyes from water.
Synthesis of a Dimeric Magnesium(I) Compound by an MgI/MgII Redox Reaction
Authors: Stasch Andreas 
Published: July 2014

AbstractThe synthesis of dimeric magnesium(I) compounds of the general type RMgMgR (R=monoanionic substituent) is still a challenging synthetic task and limited to few examples with sterically demanding ligands with delocalized CN‐frameworks that all have been accessed by Na or K metal reduction of magnesium(II) halide precursors. Here we report on the synthesis of a novel diiminophosphinato magnesium(I) compound that has been synthesized by a facile redox reaction using a known magnesium(I) complex. The synthetic strategy may be applicable to other ligand systems and can help expand the class of low oxidation state magnesium complexes even if reductions with Na or K are unsuccessful. The new dimeric magnesium(I) complex has been structurally characterized and undergoes a CC coupling reaction with tert‐butylisocyanate.
Unprecedented Role of Hydronaphthoquinone Tautomers in Biosynthesis
Authors: Husain Syed Masood , Schätzle Michael A. , Lüdeke Steffen , Müller Michael 
Published: July 2014

AbstractQuinones and hydroquinones are among the most common cellular cofactors, redox mediators, and natural products. Here, we report on the reduction of 2‐hydroxynaphthoquinones to the stable 1,4‐diketo tautomeric form of hydronaphthoquinones and their further reduction by fungal tetrahydroxynaphthalene reductase. The very high diastereomeric and enantiomeric excess, together with the high yield of cis‐3,4‐dihydroxy‐1‐tetralone, exclude an intermediary hydronaphthoquinone. Labeling experiments with NADPH and NADPD corroborated the formation of an unexpected 1,4‐diketo tautomeric form of 2‐hydroxyhydronaphthoquinone as a stable intermediate. Similar 1,4‐diketo tautomers of hydronaphthoquinones were established as products of the NADPH‐dependent enzymatic reduction of other 1,4‐naphthoquinones, and as substrates for different members of the superfamily of short‐chain dehydrogenases. We propose an essential role of hydroquinone diketo tautomers in biosynthesis and detoxification processes.
Understanding a Host–Guest Model System through 129Xe NMR Spectroscopic Experiments and Theoretical Studies
Authors: Dubost Emmanuelle , Dognon Jean‐Pierre , Rousseau Bernard , Milanole Gaëlle , Dugave Christophe , Boulard Yves , Léonce Estelle , Boutin Céline , Berthault Patrick 
Published: July 2014

AbstractGaining an understanding of the nature of host–guest interactions in supramolecular complexes involving heavy atoms is a difficult task. Described herein is a robust simulation method applied to complexes between xenon and members of a cryptophane family. The calculated chemical shift of xenon caged in a H2O2 probe, as modeled by quantum chemistry with complementary‐orbital, topological, and energy‐decomposition analyses, is in excellent agreement with that observed in hyperpolarized 129Xe NMR spectra. This approach can be extended to other van der Waals complexes involving heavy atoms.
An “All‐Green” Catalytic Cycle of Aqueous Photoionization
Authors: Goez Martin , Kerzig Christoph , Naumann Robert 
Published: July 2014

AbstractHydrated electrons are highly aggressive species that can force chemical transformations of otherwise unreactive molecules such as the reductive detoxification of halogenated organic compounds. We present the first example of the sustainable production of hydrated electrons through a homogeneous catalytic cycle driven entirely by green light (532 nm, coinciding with the maximum of the terrestrial solar spectrum). The catalyst is a metal complex serving as a “container” for a radical anion. This active center is generated from a ligand through quenching by a sacrificial electron donor, is shielded by the complex such that it stores the energy of the photon for much longer than a free radical anion could, and is finally ionized by another photon to regenerate the ligand and recover the starting complex quantitatively. The sacrificial donor can be a bioavailable reagent such as ascorbic acid.
Integrating Perovskite Solar Cells into a Flexible Fiber
Authors: Qiu Longbin , Deng Jue , Lu Xin , Yang Zhibin , Peng Huisheng 
Published: July 2014

AbstractPerovskite solar cells have triggered a rapid development of new photovoltaic devices because of high energy conversion efficiencies and their all‐solid‐state structures. To this end, they are particularly useful for various wearable and portable electronic devices. Perovskite solar cells with a flexible fiber structure were now prepared for the first time by continuously winding an aligned multiwalled carbon nanotube sheet electrode onto a fiber electrode; photoactive perovskite materials were incorporated in between them through a solution process. The fiber‐shaped perovskite solar cell exhibits an energy conversion efficiency of 3.3 %, which remained stable on bending. The perovskite solar cell fibers may be woven into electronic textiles for large‐scale application by well‐developed textile technologies.
Degradation behavior of ionic‐covalent entanglement hydrogels
Authors: De Silva D. Awanthi , Martens Penny J. , Gilmore Kerry J. , in het Panhuis Marc 
Published: July 2014

ABSTRACTIonic‐covalent entanglement (ICE) hydrogels are a recently introduced new type of robust materials for potential future application in the fields of tissue engineering and soft robotics. Here the degradation behavior of gellan gum/polyacrylamide ICE hydrogels immersed in PBS or enzyme solutions is presented. It is demonstrated that ICE gels immersed in enzymes became stiffer, whereas under cyclic testing their mechanical responses stabilize after 10 loading/unloading cycles whether immersed in PBS or enzyme solutions. The leachates of the ICE hydrogels were found to be non‐cytotoxic for the growth of L929 and PC12 cells. These findings will be of benefit to the future development of tissue engineering applications based on these gel materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 41216.
Collective Synthesis of 4‐Hydroxy‐2‐pyridone Alkaloids and Their Antiproliferation Activities
Authors: Ding Feiqing , Leow Min Li , Ma Jimei , William Ronny , Liao Hongze , Liu Xue‐Wei 
Published: July 2014

AbstractA collective synthesis of 4‐hydroxy‐2‐pyridone alkaloids—specifically, pretenellin B, prebassianin B, farinosone A, militarione D, pyridovericin, and torrubiellone C—has been achieved. Key steps include using a strategic convergent method to synthesize the densely substituted pyridone key intermediate by Suzuki–Miyaura cross‐coupling reaction, a divergent synthesis approach of target molecules by aldol condensation of pyridone intermediate with homologous aldehydes, and an iterative synthesis of homologous aldehydes with all‐trans‐polyene backbones. Interestingly, among the six tumor cell lines investigated, torrubiellone C was found to induce potent and apoptotic inhibitory activities on Jurkat T cells with IC50 values of 7.05 μM. Hence, this approach could potentially contribute to the synthesis of bioactive small‐molecule libraries as well as drug discovery.
Reactions of Cycloaliphatic Thioketones and Their Oxo Analogues with Lithiated Methoxyallene: A New Approach to Vinylthiiranes
Authors: Jasiński Marcin , Mlostoń Grzegorz , Stolarski Michał , Costa Wilhelmine , Domínguez Moises , Reissig Hans‐Ulrich 
Published: July 2014

AbstractAdmantanethione smoothly reacted with lithiated methoxyallene at low temperatures yielding the expected allenyl‐substituted thiolate, which upon aqueous work‐up underwent spontaneous 1,3‐cyclization to afford a hitherto unknown methoxy‐substituted vinylthiirane derivative. The analogous reaction with adamantanone led to the corresponding allenyl alcohol that can be isolated and—depending on the conditions applied—either be converted into the corresponding vinyloxirane or into the 2,5‐dihydrofuran derivative. Sterically more crowded thioketones were also combined with lithiated methoxyallene, but in these cases competitive 1,5‐cyclization leading to isomeric dihydrothiophene derivatives was observed. DFT calculations of model intermediates and products show distinct energy differences of the sulfur and the corresponding oxygen compounds. Desulfurization of the adamantanethione‐derived vinylthiirane yielded a methoxy‐substituted 1,3‐diene that was studied in cycloadditions with electron‐deficient dienophiles. Whereas in the case of tetracyanoethylene the corresponding cyclobutane derivative was formed, the reaction with nitrosobenzene provided the expected 1,2‐oxazine derivative. By reductive cleavage of the NO bond this heterocycle was converted into an unsaturated amino alcohol bearing an adamantane moiety.
Outcomes after endovascular or open repair for degenerative descending thoracic aortic aneurysm using linked hospital data
Authors: von Allmen R S , Anjum A , Powell J T 
Published: July 2014

Abstract

Background
The population-based effectiveness of thoracic endovascular aortic repair (TEVAR) versus open surgery for descending thoracic aortic aneurysm remains in doubt.

Methods
Patients aged over 50 years, without a history of aortic dissection, undergoing repair of a thoracic aortic aneurysm between 2006 and 2011 were assessed using mortality-linked individual patient data from Hospital Episode Statistics (England). The principal outcomes were 30-day operative mortality, long-term survival (5 years) and aortic-related reinterventions. TEVAR and open repair were compared using crude and multivariable models that adjusted for age and sex.

Results
Overall, 759 patients underwent thoracic aortic aneurysm repair, mainly for intact aneurysms (618, 81·4 per cent). Median ages of TEVAR and open cohorts were 73 and 71 years respectively (P &lt; 0·001), with more men undergoing TEVAR (P = 0·004). For intact aneurysms, the operative mortality rate was similar for TEVAR and open repair (6·5 versus 7·6 per cent; odds ratio 0·79, 95 per cent confidence interval (c.i.) 0·41 to 1·49), but the 5-year survival rate was significantly worse after TEVAR (54·2 versus 65·6 per cent; adjusted hazard ratio 1·45, 95 per cent c.i. 1·08 to 1·94). After 5 years, aortic-related mortality was similar in the two groups, but cardiopulmonary mortality was higher after TEVAR. TEVAR was associated with more aortic-related reinterventions (23·1 versus 14·3 per cent; adjusted HR 1·70, 95 per cent c.i. 1·11 to 2·60). There were 141 procedures for ruptured thoracic aneurysm (97 TEVAR, 44 open), with TEVAR showing no significant advantage in terms of operative mortality.

Conclusion
In England, operative mortality for degenerative descending thoracic aneurysm was similar after either TEVAR or open repair. Patients who had TEVAR appeared to have a higher reintervention rate and worse long-term survival, possibly owing to cardiopulmonary morbidity and other selection bias.
Factors influencing aversion to specific electrodiagnostic studies
Authors: Jerath Nivedita U. , Strader Scott B. , Reddy Chandan G. , Swenson Andrea , Kimura Jun , Aul Edward 
Published: July 2014

AbstractObjectiveTo compare the degree of discomfort caused by nerve conduction studies (NCS) versus needle electromyography (EMG), and to determine what factors predict aversion to one test or the other.MethodsTwo hundred patients underwent both EMG and NCS, and were asked to indicate which test was more uncomfortable. Responses were then correlated with demographic information, testing characteristics, and medical histories to identify any notable associations.ResultsOf the 200 patients, 58.5% (117) of the patients found the NCS more uncomfortable than EMG. Sixty‐one percent (11/18) of the younger patients (18–29 years old) found EMG more uncomfortable (P = 0.08), whereas 68% (40/59) of the older patients (age greater than 60 years old) found NCS more uncomfortable (P = 0.05). Sixty‐seven percent (14/21) of the patients whose BMI was less than 22 kg/m2 rated EMG as more uncomfortable (P = 0.01). Sixty‐nine percent (27/39) of the patients whose BMI was greater than or equal to 38 found the NCS more uncomfortable (P = 0.02). A positive correlation existed between NCS discomfort and number of nerves tested. 67% (35/52) of the patients with polyneuropathy found NCS more uncomfortable.ConclusionNerve conduction studies are more uncomfortable than needle EMG in the majority of patients, and predictions regarding which test will be more uncomfortable for a given patient are possible.
Self‐Assembly of Fullerene‐Based Janus Particles in Solution: Effects of Molecular Architecture and Solvent
Authors: Lin Zhiwei , Lu Pengtao , Hsu Chih‐Hao , Yue Kan , Dong Xue‐Hui , Liu Hao , Guo Kai , Wesdemiotis Chrys , Zhang Wen‐Bin , Yu Xinfei , Cheng Stephen Z. D. 
Published: July 2014

AbstractTwo molecular Janus particles based on amphiphilic [60]fullerene (C60) derivatives were designed and synthesized by using the regioselective Bingel–Hirsh reaction and the click reaction. These particles contain carboxylic acid functional groups, a hydrophilic fullerene (AC60), and a hydrophobic C60 in different ratios and have distinct molecular architectures: 1:1 (AC60–C60) and 1:2 (AC60–2C60). These molecular Janus particles can self‐assemble in solution to form aggregates with various types of micellar morphology. Whereas vesicular morphology was observed for both AC60–C60 and AC60–2C60 in tetrahydrofuran, in a mixture of N,N‐dimethylformamide (DMF)/water, spherical micelles and cylindrical micelles were observed for AC60–C60 and AC60–2C60, respectively. A mechanism of formation was tentatively proposed based on the effects of molecular architecture and solvent polarity on self‐assembly.
Pd‐Catalysed Mono‐ and Dicarbonylation of Aryl Iodides: Insights into the Mechanism and the Selectivity
Authors: Fernández‐Alvarez Victor M. , de la Fuente Verónica , Godard Cyril , Castillón Sergio , Claver Carmen , Maseras Feliu , Carbó Jorge J. 
Published: July 2014

AbstractThe mechanism of the experimentally reported phosphine‐free palladium‐catalysed carbonylation of aryl iodides with amines in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) as base was investigated at the DFT level. Paths were identified for both di‐ and monocarbonylation, and the calculated selectivity for three different substrates was in agreement with experiment. In dicarbonylation yielding α‐ketoamides, formation of the second carbon–carbon bond occurs through reductive elimination in the Pd acyl amide intermediate after DBU‐assisted nucleophilic attack of an amine at a terminal CO ligand. This path yields the major product with iodobenzene and the almost exclusive product with p‐methoxyiodobenzene. Two different possible pathways yield the monocarbonylated amide product. In one of them, which affords the minor product for iodobenzene, base‐assisted nucleophilic attack of the amine takes place on a Pd‐bound acyl ligand. For substrates with electron‐withdrawing substituents, such as p‐cyanoiodobenzene, aryl migration to the CO ligand is disfavoured, and this allows base‐assisted amine attack at a terminal CO ligand early in the catalytic cycle. From the resulting Pd amide aryl complex, the subsequent reductive elimination occurs easily, and monocarbonylation becomes favoured.
Stabilization of a Two‐Coordinate Mononuclear Cobalt(0) Compound
Authors: Mondal Kartik Chandra , Roy Sudipta , De Susmita , Parameswaran Pattiyil , Dittrich Birger , Ehret Fabian , Kaim Wolfgang , Roesky Herbert W. 
Published: July 2014

AbstractCompound (Me2‐cAAC:)2Co0 (2; Me2‐cAAC:=cyclic (alkyl) amino carbene; :C(CH2)(CMe2)2N‐2,6‐iPr2C6H3) was synthesized by the reduction of the precursor (Me2‐cAAC:)2CoICl (1) with KC8 in THF. The cyclic voltammogram of 1 exhibited one‐electron reduction, which suggests that synthesis of a bent 2‐metallaallene (2) from 1 should be possible. Compound 2 contains one cobalt atom in the formal oxidation state zero, which is stabilized by two Me2‐cAAC: ligands. Bond lengths from X‐ray diffraction are 1.871(2) and 1.877(2) Å with a C‐Co‐C bond angle of 170.12(8)°. The EPR spectrum of 2 exhibited a broad resonance attributed to the unique quasi‐linear structure, which favors near degeneracy and gives rise to very rapid relaxation conditions. The cAACCo bond in 2 can be considered as a typical Dewar–Chatt–Duncanson type of bonding, which in turn retains 2.5 electron pairs on the Co atom as nonbonding electrons.
Effects of experimental sedimentation on the phenological dynamics and leaf traits of replanted mangroves at Gazi bay, Kenya
Authors: Okello Judith A. , Robert Elisabeth M. R. , Beeckman Hans , Kairo James G. , Dahdouh‐Guebas Farid , Koedam Nico 
Published: July 2014

Abstract

Sedimentation results in the creation of new mudflats for mangroves to colonize among other benefits. However, large sediment input in mangrove areas may be detrimental to these forests. The dynamics of phenological events of three mangrove tree species (Avicennia marina, Ceriops tagal, and Rhizophora mucronata) were evaluated under experimental sediment burial simulating sedimentation levels of 15, 30, and 45 cm.

While there was generally no shift in timing of phenological events with sedimentation, the three mangrove tree species each responded differently to the treatments.

Partially buried A. marina trees produced more leaves than the controls during the wet season and less during the dry season. Ceriops tagal on the other hand had higher leaf loss and low replacement rates in the partially buried trees during the first 6 months of the experiment but adapted with time, resulting in either equal or higher leaf emergence rates than the controls.

Rhizophora mucronata maintained leaf emergence and loss patterns as the unaffected controls but had a higher fecundity and productivity in the 15‐cm sedimentation level.

The results suggest that under incidences of large sedimentation events (which could be witnessed as a result of climate change impacts coupled with anthropogenic disturbances), mangrove trees may capitalize on “advantages” associated with terrestrial sediment brought into the biotope, thus maintaining the pattern of phenological events.
Mixed‐Donor Amido–Siloxo Actinide(IV) Halide and Alkyl Complexes with an Aryl Cipso Interaction
Authors: Hayes Cassandra E. , Gill Dayle E. , Brown Matthew L. , Leznoff Daniel B. 
Published: July 2014

AbstractThe synthesis and characterisation of a series of new actinide(IV) complexes supported by the mixed‐donor amido–amino–siloxo framework [RN(Li)SiMe2N(R)SiMe2OLi] ([RNNO]Li2; R = 2,4,6‐Me3Ph, 2,6‐iPr2Ph) are presented. The reaction of 1 equiv. of [RNNO]Li2 with ThCl4·2DME (DME = 1,2‐dimethoxyethane) in DME generated {Li·nDME}{[RNNO]2Th2Cl5} (1: R = 2,4,6‐Me3Ph, n = 2; 2: R = 2,6‐iPr2Ph, n = 3) in high yield, and the addition of [NNO]Li2 to UCl4 in tetrahydrofuran (THF) resulted in the formation of {[NNO]UCl3Li·THF}2 (3). The structures of 1–3 indicate that they retain LiCl as “ate” complexes. The addition of 2 equiv. of [NNO]Li2 to ThCl4·2DME and UCl4 gives the bis‐ligated complexes [NNO]2ThClLi (4) and [NNO]2U (5), respectively. In 1–5, the [RNNO]2– ligands all coordinate through the amido and siloxo donors as well as the ipso carbon atom of the phenyl group of the amido ligand but not through the central amino group. Complex 3 can be alkylated through the addition of 2 equiv. of LiCH2SiMe3 to give [NNO]U(CH2SiMe3)2 (6) or NaCp (Cp = cyclopentadienyl) to give [NNO]UCp2 (7); the latter has been structurally characterised.
Synthesis, Stability, and Photoreactivity of Diazirinyl‐SubstitutedN‐Heterocycles Based on Indole, Benzimidazole, and Imidazole
Authors: Raimer Björn , Wartmann Thomas , Jones Peter G. , Lindel Thomas 
Published: July 2014

AbstractThe synthesis, thermal stability, and photoreactivity of trifluoromethyl diazirines installed at the heterocyclic section ofN‐methylindole,N‐methylbenzimidazole, and atN‐methylimidazole were investigated.N‐Tosyl‐3‐diazirinylindole andN‐methyl‐2‐diazirinylbenzimidazole proved to be thermally stable, whereas the corresponding 2‐diazirinylindole was not. The least stable was 2‐diazirinylimidazole, which underwent rapid decomposition. Quenching with ethanol indicated that the corresponding carbene was formed. Decomposition is rationalized by exothermic coarctate ring‐opening of the carbene. Quantum mechanical calculations [B3LYP/6‐311G(2d,2p)] predict singlet ground states of all carbenes. Accordingly, Friedel–Crafts alkylation products were formed on irradiation (350 nm, Rayonet) of theN‐methylbenzimidazole‐based diazirine in the presence of phenol.
Electrochemical Deoxygenation of Aromatic Amides and Sulfoxides
Authors: Edinger Carolin , Waldvogel Siegfried R. 
Published: July 2014

AbstractThe electrochemical deoxygenation of a broad range of aromatic amides was achieved under mild conditions on lead cathodes. Under the optimized reaction conditions, acetal, thienyl, and ether moieties are tolerated. Furthermore, the reduction protocol can be applied to aromatic and aliphatic sulfoxides to obtain the corresponding sulfides. For both aromatic amides and sulfoxides, the deoxygenation reaction ensues without the use of expensive catalysts or hazardous reducing agents. Owing to the high selectivity of the process, simple extraction is sufficient to isolate the product from the substrate. The straightforward purification protocol, the coformation of water, and the use of electric current instead of reducing agents render our method environmentally friendly and economically beneficial.