Fluorinated acrylates via alkoxycarbonylation of 1-alkynes with fluorinated alcohols

The system formed by combining in situ Pd(OAc)₂ with (2-pyridyl)diphenylphosphine (PyPPh₂) and CH₃SO₃H catalyzes efficiently the carbonylation of terminal alkynes (phenylacetylene or 1-hexyne) with alcohols having perfluorinated segments of the type CF₃(CF₂)_m(CH₂)_n–OH (m=1 or 3, n=1, 2 or 3) or with pentafluorophenol. Good carbonylation rates accompanied by high regioselectivity towards acrylate ester formation are obtained under mild reaction conditions (T=60–80 °C, P(CO)=30 atm). The influence of the CO pressure, the catalyst composition, the temperature and the number (n) of protonated methylene groups on the catalysis has been studied.     

A Poincar�� Inequality for Orlicz�CSobolev Functions with Zero Boundary Values on Metric Spaces

We prove a Poincaré inequality for Orlicz–Sobolev functions with zero boundary values in bounded open subsets of a metric measure space. This result generalizes the (p, p)-Poincaré inequality for Newtonian functions with zero boundary values in metric measure spaces, as well as a Poincaré inequality for Orlicz–Sobolev functions on a Euclidean space, proved by Fuchs and Osmolovski (J Anal Appl (Z.A.A.) 17(2):393–415, 1998). Using the Poincaré inequality for Orlicz–Sobolev functions with zero boundary values we prove the existence and uniqueness of a solution to an obstacle problem for a variational integral with nonstandard growth.     

Injectivity Conditions in the Complex Plane

We give a survey on some recent results concerning injectivity conditions in the complex plane, which are obtained by using certain geometric properties (as starlikeness, spiralikeness, convexity, close-to-convexity). These results extend to continuously differentiable maps some well-known univalence conditions for analytic functions.     

Detection of early stage precursor during formation of plastic crystal ethanol from the supercooled liquid state: a simultaneous dielectric spectroscopy with neutron diffraction study

Transformation of deuterated ethanol from supercooled liquid into a plastic crystal or rotator phase is investigated by means of a particular experimental setup combining simultaneously dielectric spectroscopy with neutron diffraction techniques. We demonstrate that, previous to the growth of the bcc lattice of the plastic crystal phase, the formation of a precursor or intermediate phase through a liquid-liquid phase separation takes place. Once this precursor phase is formed, subsequent (plastic) crystalline nucleation and growth is expected to develop.     

Suzuki-Miyaura cross-coupling of aryl carbamates and sulfamates: experimental and computational studies

The first Suzuki-Miyaura cross-coupling reactions of the synthetically versatile aryl O-carbamate and O-sulfamate groups are described. The transformations utilize the inexpensive, bench-stable catalyst NiCl(2)(PCy(3))(2) to furnish biaryls in good to excellent yields. A broad scope for this methodology has been demonstrated. Substrates with electron-donating and electron-withdrawing groups are tolerated, in addition to those that possess ortho substituents. Furthermore, heteroaryl substrates may be employed as coupling partners. A computational study providing the full catalytic cycles for these cross-coupling reactions is described. The oxidative addition with carbamates or sulfamates occurs via a five-centered transition state, resulting in the exclusive cleavage of the aryl C-O bond. Water is found to stabilize the Ni-carbamate catalyst resting state, which thus provides rationalization of the relative decreased rate of coupling of carbamates. Several synthetic applications are presented to showcase the utility of the methodology in the synthesis of polysubstituted aromatic compounds of natural product and bioactive molecule interest.     

Thermodynamic and structural features of aqueous Ce(III)

With a single f-electron, Ce(III) is the simplest test case for benchmarking the thermodynamic and structural properties of hydrated Ln(III) against varying density functionals and reaction field models, in addition to determining the importance of multiconfigurational character in their wave functions. Here, the electronic structure of Ce(H2O)x(H 2O)y(3+) (x = 8, 9; y = 0, 12-14) has been examined using DFT and CASSCF calculations. The latter confirmed that the wave function of octa- and nona-aqua Ce(III) is well-described by a single configuration. Benchmarking was performed for density functionals, reaction field cavity types, and solvation reactions against the experimental free energy of hydration, DeltaG(hyd)(Ce(3+)). The UA0, UAKS, Pauling, and UFF polarized continuum model cavities displayed different performance, depending on whether one or two hydration shells were examined, and as a function of the size of the metal basis set. These results were essentially independent of the density functional employed. Using these benchmarks, the free energy for water exchange between CN = 8 and CN = 9, for which no experimental data are available, was estimated to be approximately -4 kcal/mol.     

Synthesis of palladium(II) complexes containing a new alpha-D-xylofuranose-modified diphosphine and their application as catalyst precursors in the co- and terpolymerization of CO-ethene and propene

The diphosphine 3,5-dideoxy-1,2-O-isopropylidene-3,5-bis(di(2-methoxyphenyl)phosphanyl)-alpha-D-xylofuranose (o-MeO-xylophos), which differs from the known 3,5-dideoxy-1,2-O-isopropylidene-3,5-bis(diphenylphosphanyl)-alpha-D-xylofuranose (xylophos) by the presence of 2-methoxy substituents on the P-aryl rings, has been synthesized and characterized. These two ligands have been employed to stabilize the Pd(II) complexes [PdCl2(o-MeO-xylophos)] (1a), [PdCl2(xylophos)] (2a), [PdClMe(o-MeO-xylophos)] (1b), [PdClMe(xylophos)] (2b), [Pd(OTs)(H2O)(o-MeO-xylophos)](OTs) (1c) and [Pd(OTs)(H2O)(xylophos)](OTs) (2c). All complexes have been characterized by multinuclear-NMR spectroscopy. The solid-state structure of 1a has been determined by a single crystal X-ray analysis. The Pd-aqua complexes 1c and 2c have been employed to catalyse the CO-ethene and CO-propene copolymerization as well as the CO-ethene-propene terpolymerization reaction in MeOH. The catalytic activity and the molecular weight of the polyketones have been compared to those of the products obtained with analogous catalysts, [Pd(H2O)2(o-MeO-dppp)](OTs)2 (3c) and [Pd(H2O)(OTs)(dppp)](OTs) (4c), bearing the classical 1,3-bis(diphenylphoshino)propane ligand (dppp). Under comparable catalytic conditions, all catalysts produce structurally similar polymeric materials, with 1c yielding the largest propene incorporation as well as the highest productivity of low-molecular-weight terpolymers.     

Engineering mono- and multi-valent inhibitors on a modular scaffold

Here we exploit the simple, ultra-stable, modular architecture of consensus-designed tetratricopeptide repeat proteins (CTPRs) to create a platform capable of displaying both single as well as multiple functions and with diverse programmable geometrical arrangements by grafting non-helical short linear binding motifs (SLiMs) onto the loops between adjacent repeats. As proof of concept, we built synthetic CTPRs to bind and inhibit the human tankyrase proteins (hTNKS), which play a key role in Wnt signaling and are upregulated in cancer. A series of mono-valent and multi-valent hTNKS binders was assembled. To fully exploit the modular scaffold and to further diversify the multi-valent geometry, we engineered the binding modules with two different formats, one monomeric and the other trimeric. We show that the designed proteins are stable, correctly folded and capable of binding to and inhibiting the cellular activity of hTNKS leading to downregulation of the Wnt pathway. Multivalency in both the CTPR protein arrays and the hTNKS target results in the formation of large macromolecular assemblies, which can be visualized both in vitro and in the cell. When delivered into the cell by nanoparticle encapsulation, the multivalent CTPR proteins displayed exceptional activity. They are able to inhibit Wnt signaling where small molecule inhibitors have failed to date. Our results point to the tremendous potential of the CTPR platform to exploit a range of SLiMs and assemble synthetic binding molecules with built-in multivalent capabilities and precise, pre-programmed geometries.     

Bioactive Co(II), Ni(II), and Cu(II) Complexes Containing a Tridentate Sulfathiazole-Based (ONN) Schiff Base

New Co(II), Ni(II), and Cu(II) complexes were synthesized with the Schiff base ligand obtained by the condensation of sulfathiazole with salicylaldehyde. Their characterization was performed by elemental analysis, molar conductance, spectroscopic techniques (IR, diffuse reflectance and UV–Vis–NIR), magnetic moments, thermal analysis, and calorimetry (thermogravimetry/derivative thermogravimetry/differential scanning calorimetry), while their morphological and crystal systems were explained on the basis of powder X-ray diffraction results. The IR data indicated that the Schiff base ligand is tridentate coordinated to the metallic ion with two N atoms from azomethine group and thiazole ring and one O atom from phenolic group. The composition of the complexes was found to be of the [ML₂]∙nH₂O (M = Co, n = 1.5 (1); M = Ni, n = 1 (2); M = Cu, n = 4.5 (3)) type, having an octahedral geometry for the Co(II) and Ni(II) complexes and a tetragonally distorted octahedral geometry for the Cu(II) complex. The presence of lattice water molecules was confirmed by thermal analysis. XRD analysis evidenced the polycrystalline nature of the powders, with a monoclinic structure. The unit cell volume of the complexes was found to increase in the order of (2) < (1) < (3). SEM evidenced hard agglomerates with micrometric-range sizes for all the investigated samples (ligand and complexes). EDS analysis showed that the N:S and N:M atomic ratios were close to the theoretical ones (1.5 and 6.0, respectively). The geometric and electronic structures of the Schiff base ligand 4-((2-hydroxybenzylidene) amino)-N-(thiazol-2-yl) benzenesulfonamide (HL) was computationally investigated by the density functional theory (DFT) method. The predictive molecular properties of the chemical reactivity of the HL and Cu(II) complex were determined by a DFT calculation. The Schiff base and its metal complexes were tested against some bacterial strains (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Bacillus subtilis). The results indicated that the antibacterial activity of all metal complexes is better than that of the Schiff base.