Towards "homeopathic" palladium-catalysed alkoxycarbonylation of aliphatic and aromatic olefins.

Palladium-catalysed alkoxycarbonylation of alkenes allows for atom-efficient synthesis of esters from easily available alkenes in an industrially viable manner. One of the major costs associated with this process is the consumption of the catalyst system. Hence, for economic and ecologic reasons it is desirable to minimize the amount of metal and ligands wherever possible. Herein, we report "a homeopathic" palladium-catalysed alkoxycarbonylation of olefins under comparably mild conditions. The key to success is the homemade ligand LIKATphos providing good to excellent yields of ester products with catalyst turnover numbers in the range of 106.

Crystalline Order Propagates Across Thick Layers of Water in Solutions of Supramolecular Nanotubes.

3D crystalline order with 1 nm resolution is observed in aqueous solutions of supramolecular nanotubes containing 94 % water, at concentrations as low as 6 wt%. 50 of star-like organic ions arrange into supramolecular rings which, in turn, stack on top of each other to form long hollow tubes with 15 nm outer diameter. Cryo-TEM and X-ray diffraction show that the parallel nanotubes arrange on a perfect hexagonal lattice. Unexpectedly, fiber diffraction on sheared solutions revealed numerous hkl Bragg reflections on several layer lines indicating longitudinal interlock between the tubes and 3D crystalline order with molecular-scale details transferred across 10 nm thick layers of water. The observed high 3D order is attributed to long-range attraction between like-charged tubes and amplified charge modulation by the extremely high intra-tube correlation length.

A split-and-merge deep learning approach for phenotype prediction.

BACKGROUND: Phenotype prediction with genome-wide markers is a critical but difficult problem in biomedical research due to many issues such as nonlinearity of the underlying genetic mapping and high-dimensionality of marker data. When using the deep learning method in the small-n-large-p data, some serious issues occur such as over-fitting, over-parameterization, and biased prediction. METHODS: In this study, we propose a split-and-merge deep learning method, named SM-DL method, to learn a neural network on the dimension reduce data by using the split-and-merge technique. CONCLUSIONS: Numerically, the proposed method has significant performance in phenotype prediction for a simulated example. A real example is used to demonstrate how the proposed method can be applied in practice.

Iridium-Catalyzed Domino Hydroformylation/Hydrogenation of Olefins to Alcohols: Synergy of Two Ligands.

A novel one-pot iridium-catalyzed domino hydroxymethylation of olefins, which relies on using two different ligands at the same time, is reported. DFT computation reveals different activities for the individual hydroformylation and hydrogenation steps in the presence of mono- and bidentate ligands. Whereas bidentate ligands have higher hydrogenation activity, monodentate ligands show higher hydroformylation activity. Accordingly, a catalyst system is introduced that uses dual ligands in the whole domino process. Control experiments show that the overall selectivity is kinetically controlled. Both computation and experiment explain the function of the two optimized ligands during the domino process.

A general strategy for the synthesis of α-trifluoromethyl- and α-perfluoroalkyl-ß-lactams via palladium-catalyzed carbonylation.

ß-Lactam compounds play a key role in medicinal chemistry, specifically as the most important class of antibiotics. Here, we report a novel one-step approach for the synthesis of α-(trifluoromethyl)-ß-lactams and related products from fluorinated olefins, anilines and CO. Utilization of an advanced palladium catalyst system with the Ruphos ligand allows for selective cycloaminocarbonylations to give diverse fluorinated ß-lactams in high yields.

Efficient Palladium-Catalyzed Carbonylation of 1,3-Dienes: Selective Synthesis of Adipates and Other Aliphatic Diesters.

The dicarbonylation of 1,3-butadiene to adipic acid derivatives offers the potential for a more cost-efficient and environmentally benign industrial process. However, the complex reaction network of regioisomeric carbonylation and isomerization pathways, make a selective and direct transformation particularly difficult. Here, we report surprising solvent effects on this palladium-catalysed process in the presence of 1,2-bis-di-tert-butylphosphin-oxylene (dtbpx) ligands, which allow adipate diester formation from 1,3-butadiene, carbon monoxide, and methanol with 97 % selectivity and 100 % atom-economy under scalable conditions. Under optimal conditions a variety of di- and triesters from 1,2- and 1,3-dienes can be obtained in good to excellent yields.

Direct and Selective Synthesis of Adipic and Other Dicarboxylic Acids by Palladium-Catalyzed Carbonylation of Allylic Alcohols.

A general and direct synthesis of dicarboxylic acids including industrially important adipic acid by palladium-catalyzed dicarbonylation of allylic alcohol is reported. Specifically, the combination of PdCl2 and a bisphosphine ligand (HeMaRaphos) promotes two different carbonylation reactions with high activity and excellent selectivity.

Positional Order in the Columnar Phase of Lyotropic Chromonic Liquid Crystals Mediated by Ionic Additives.

Positional order in the lyotropic chromonic liquid crystals (LCLCs) is investigated in the supramolecular assembly of benzene 1,3,5-tricarboxamide (BTA) derivatives with the glucono-delta-lactone (GdL) acid additive by high-resolution synchrotron radiation small-angle X-ray scattering. The formation of positionally ordered hexagonal phase is found to profoundly depend on the concentrations of BTA derivatives, c BTA, and GdL additives, c addtive, giving rise to unusual behavior distinctive from conventional lyotropic liquid crystals (LCs) with covalent bonds and fixed length. The hexagonal phase is observed to coexist with another phase in certain range of c addtive/c BTA. Intriguingly, the lattice spacing R of the hexagonal phase remains almost constant by varying c addtive but changes with c BTA. The above observations are attributed to unique sensitivities of the LCLC properties, such as the contour length and flexibility of individual cylinder assemblies and phase coexistence, to additives in the solutions. Our study reveals the complexity in positional ordering in the LCLCs which not only relates to the underlying principles of hierarchical reversible self-assembly but also attracts fundamental interests in LCs.

A general platinum-catalyzed alkoxycarbonylation of olefins.

Hydroxy- and alkoxycarbonylation reactions constitute important industrial processes in homogeneous catalysis. Nowadays, palladium complexes constitute state-of-the-art catalysts for these transformations. Herein, we report the first efficient platinum-catalysed alkoxycarbonylations of olefins including sterically hindered and functionalized ones. This atom-efficient catalytic transformation provides straightforward access to a variety of valuable esters in good to excellent yields and often with high selectivities. In kinetic experiments the activities of Pd- and Pt-based catalysts were compared. Even at low catalyst loading, Pt shows high catalytic activity.

The pathway and kinetics of hierarchical assembly of ionic oligomers into a lyotropic columnar phase.

Ionic benzene-1,3,5-tricarboxamide (BTA) molecules can self-assemble into hollow cylinders which further arrange into columnar phases in water. In situ investigations suggest a multi-step pathway of supramolecular assembly via formation of dispersed molecular aggregates followed by a less ordered intermediate phase before the equilibrium columnar phase is formed. The pathway and kinetics of the formation of lyotropic LC phases through hierarchical supramolecular assembly are similar to non-classical crystallization, in line with an emerging holistic view on crystallization and self-assembly.

Significant effects of exposure to relatively low level ozone on daily mortality in 17 cities from three Eastern Asian Countries.

BACKGROUND: Studies have examined the variation in mortality risk associated with ambient ozone. We conducted an international cooperation study for investigating the non-linear ozone-mortality association accounting for lag effect and for examining the ozone level with significant health effect. METHODS: Daily counts of total non-accidental death and ambient air pollutant concentration were obtained in 17 cities from 3 Eastern Asian countries or regions (Taiwan, Korea, and Japan). The total study period was from 1979 to 2010 and differed by city based on data availability. The ozone-mortality association in each city was estimated by running a time-series quasi-Poisson regression model, allowing for overdispersion. The city-specific estimates were then pooled by country by using multivariate random effects meta-analysis. RESULTS: The non-linear ozone exposure-mortality response curves were generated in 17 cities from Taiwan, Korea, and Japan. The association curves in the three countries all showed increased mortality with elevated ozone, and the significant mortality effects of ozone exposure were observed at level higher than 40, 50, and 40 ppb for Taiwan, Korea, and Japan, respectively. These associations are unaffected by co-pollutant of particulate matter in Taiwan and Japan. But the potential confounding effect of co-pollutant could not be ignorable in Korea. CONCLUSIONS: Our study provides evidence that exposure to a relative low level of ambient ozone is associated with an increased risk of mortality. Our results emphasize the continual need to examine the existing standard by documenting potential human adverse effects.

Multivariate multiple regression models of poly(ethylene-terephthalate) film degradation under outdoor and multi-stressor accelerated weathering exposures.

Developing materials for use in photovoltaic (PV) systems requires knowledge of their performance over the warranted lifetime of the PV system. Poly(ethylene-terephthalate) (PET) is a critical component of PV module backsheets due to its dielectric properties and low cost. However, PET is susceptible to environmental stressors and degrades over time. Changes in the physical properties of nine PET grades were modeled after outdoor and accelerated weathering exposures to characterize the degradation process of PET and assess the influence of stabilizing additives and weathering factors. Multivariate multiple regression (MMR) models were developed to quantify changes in color, gloss, and haze of the materials. Natural splines were used to capture the non-linear relationship between predictors and responses. Model performance was evaluated via adjusted-R2 and root mean squared error values from leave-one-out cross validation analysis. All models described over 85% of the variation in the data with low relative error. Model coefficients were used to assess the influence of weathering stressors and material additives on the property changes of films. Photodose was found to be the primary degradation stressor and moisture was found to increase the degradation rate of PET. Direct moisture contact was found to impose more stress on the material than airbone moisture (humidity). Increasing the concentration of TiO2 was found to generally decrease the degradation rate of PET and mitigate hydrolytic degradation. MMR models were compared to physics-based models and agreement was found between the two modeling approaches. Cross-correlation of accelerated exposures to outdoor exposures was achieved via determination of cross-correlation scale factors. Cross-correlation revealed that direct moisture contact is a key factor for reliable accelerated weathering testing and provided a quantitative method to determine when accelerated exposure results can be made more aggressive to better approximate outdoor exposure conditions.

Lyotropic meso-phase behavior of supra-molecular nanotubes with helical charge distribution.

We report diverse meso-phase arrangements of supra-molecular nanotubes assembled by ionic benzene-1,3,5-tricarboxamide (BTA) molecules in water; their transition pathway and equilibrium structure are controlled by the helical structure. Besides, the different sensitivity to the condition of initial solutions is revealed for the final rectangular phase and the intermediate phase.