Extended Hydrogen-Bonded Molybdenum Arrays Derived from Carboxylic Acids and Dianilines: ROP Capability of the Complexes and Parent Acids and Dianilines

From reactions involving sodium molybdate and dianilines [2,2′-(NH2)C6H4]2(CH2)n (n = 0, 1, 2) and amino-functionalized carboxylic acids 1,2-(NH2)(CO2H)C6H4 or 2-H2NC6H3-1,4-(CO2H)2, in the presence of Et3N and Me3SiCl, products adopting H-bonded networks have been characterized. In particular, the reaction of 2,2′-diaminobiphenyl, [2,2′-NH2(C6H4)]2, and 2-aminoterephthalic acid, H2NC6H3-1,4-(CO2H)2, led to the isolation of [(MoCl3[2,2′-N(C6H4)]2}{HNC6H3-1-(CO2),4-(CO2H)]·2[2,2′-NH2(C6H4)]2·3.5MeCN (1·3.5MeCN), which contains intra-molecular N–H∙∙∙Cl H-bonds and slipped π∙∙∙π interactions. Similar use of 2,2′-methylenedianiline, [2,2′-(NH2)C6H4]2CH2, in combination with 2-aminoterephthalic acid led to the isolation of [MoCl2(O2CC6H3NHCO2SiMe3)(NC6H4CH2C6H4NH2)]·3MeCN (2·3MeCN). Complex 2 contains extensive H-bonds between pairs of centrosymmetrically-related molecules. In the case of 2,2′ethylenedianiline, [2,2′-(NH2)C6H4]2CH2CH2, and anthranilic acid, 1,2-(NH2)(CO2H)C6H4, reaction with Na2MoO4 in the presence of Et3N and Me3SiCl in refluxing 1,2-dimethoxyethane afforded the complex [MoCl3{1,2-(NH)(CO2)C6H4}{NC6H4CH2CH2C6H4NH3}]·MeCN (3·MeCN). In 3, there are intra-molecular bifurcated H-bonds between NH3 H atoms and chlorides, whilst pairs of molecules H-bond further via the NH3 groups to the non-coordinated carboxylate oxygen, resulting in H-bonded chains. Complexes 1 to 3 have been screened for the ring opening polymerization (ROP) of both ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL) using solvent-free conditions under N2 and air. The products were of moderate to high molecular weight, with wide Ð values, and comprised several types of polymer families, including OH-terminated, OBn-terminated (for PCL only), and cyclic polymers. The results of metal-free ROP using the dianilines [2,2′-(NH2)C6H4]2(CH2)n (n = 0, 1, 2) and the amino-functionalized carboxylic acids 1,2-(NH2)(CO2H)C6H4 or 2-H2NC6H3-1,4-(CO2H)2 under similar conditions (no BnOH) are also reported. The dianilines were found to be capable of the ROP of δ-VL (but not ε-CL), whilst anthranilic acid outperformed 2-aminoterephthalic acid for both ε-Cl and δ-VL

Rheology of protein-stabilised emulsion gels envisioned as composite networks. 1 - Comparison of pure droplet gels and protein gels

Protein-stabilised emulsion gels can be studied in the theoretical framework of colloidal gels, because both protein assemblies and droplets may be considered as soft colloids. These particles differ in their nature, size and softness, and these differences may have an influence on the rheological properties of the gels they form. Pure gels made of milk proteins (sodium caseinate), or of sub-micron protein-stabilised droplets, were prepared by slow acidification of suspensions at various concentrations. Their microstructure was characterised, their viscoelasticity, both in the linear and non-linear regime, and their frequency dependence were measured, and the behaviour of the two types of gels was compared. Protein gels and droplet gels were found to have broadly similar microstructure and rheological properties when compared at fixed volume fraction, a parameter derived from the study of the viscosity of the suspensions formed by proteins and by droplets. The viscoelasticity displayed a power law behaviour in concentration, as did the storage modulus in frequency. Additionally, strain hardening was found to occur at low concentration. These behaviours differed slightly between protein gels and droplet gels, showing that some specific properties of the primary colloidal particles play a role in the development of the rheological properties of the gels.Comment: 27 pages, 6 figure

Cocrystals of Barbituric Acid with Alkali Metal Halides

Barbituric acid BAH reacts with potassium, rubidium and caesium iodides in methanol, forming anhydrous BAH·MI. BAH·CsI has a different 8-fold coordination geometry from corresponding alkali metal bromides, intermediate between triangular dodecahedral and square antiprismatic. BAH·KI and BAH·RbI display features that are new for this family, with a high coordination number of 9, and with no involvement of iodide in either coordination or hydrogen bonding, its environment being six BAH molecules. BAH·NaCl·2H2O, prepared by successive treatment of BAH in water with sodium hydroxide and dilute hydrochloric acid, is isostructural with other chlorides and bromides, with 7-coordinate Na+ and a network of hydrogen bonding. Two BAH molecules are oxidatively coupled by aqueous potassium permanganate to generate 5-hydroxyhydurilic acid, isolated as a hydrated potassium salt with K+ in an unusually low 5-coordination. The folding of the BAH molecule in its full range of known crystal structures is analysed; the dihedral folding angle ranges from 0 to approximately 20 °, uncorrelated with any other particular features of the structures. This work is licensed under a Creative Commons Attribution 4.0 International License

Rheology of protein-stabilised emulsion gels envisioned as composite networks. 2 - Framework for the study of emulsion gels

The aggregation of protein-stabilised emulsions leads to the formation of emulsion gels. These soft solids are classically envisioned as droplet-filled matrices. Here however, it is assumed that protein-coated sub-micron droplets contribute to the network formation in a similar way to proteins. Emulsion gels are thus envisioned as composite networks made of proteins and droplets. Emulsion gels with a wide range of composition are prepared and their viscoelasticity and frequency dependence are measured. Their rheological behaviours are then analysed and compared with the properties of pure gels presented in the first part of this study. The rheological behaviour of emulsion gels is shown to depend mostly on the total volume fraction, while the composition of the gel indicates its level of similarity with either pure droplet gels or pure protein gels. These results converge to form an emerging picture of protein-stabilised emulsion gel as intermediate between droplet and protein gels. This justifies a posteriori the hypothesis of composite networks, and opens the road for the formulation of emulsion gels with fine-tuned rheology.Comment: 22 pages, 5 figure

NPDES Phase II and North Carolina Counties

The federal laws governing water quality are still changing to meet the challenge set out by the Clean Water Act. Storm water runoff, which is regulated under the National Pollutant Discharge Elimination System (NPDES), is one of the main contributors to water quality problems. The Environmental Protection Agency (EPA), which is responsible for administering NPDES, has begun Phase II of the program. This phase targets smaller storm water conveyance systems than did the first phase. This paper discusses a problem that North Carolina has had in implementing Phase II rules. Although counties are responsible for the storm water drainage systems that they own, most storm water drainage systems exist in road right-of-ways, and these right-of-ways are not owned by county governments. The roads, and their drainage systems, are owned by the North Carolina Department of Transportation (NCDOT); yet DOT does not have the land use authority to regulate the developments that send water into these drainage systems. An examination of the laws makes it clear that the state should hold counties with Phase II permits accountable for storm water runoff conveyance systems in unincorporated areas, despite the confusion over who owns the storm water runoff conveyance systems. The paper looks at five different counties to assess the level of burden the regulations will place on county governments, if counties are given responsibility for Phase II permits throughout their jurisdiction. The five counties represent different levels of urbanization and land use or storm water controls.Master of City and Regional Plannin

Detection of Far-Infrared Water Vapor, Hydroxyl, and Carbon Monoxide Emissions from the Supernova Remnant 3C 391

We report the detection of shock-excited far-infrared emission of H2O, OH, and CO from the supernova remnant 3C 391, using the ISO Long-Wavelength Spectrometer. This is the first detection of thermal H2O and OH emission from a supernova remnant. For two other remnants, W~28 and W~44, CO emission was detected but OH was only detected in absorption. The observed H2O and OH emission lines arise from levels within ~400 K of the ground state, consistent with collisional excitation in warm, dense gas created after the passage of the shock front through the dense clumps in the pre-shock cloud. The post-shock gas we observe has a density ~2x10^5 cm^{-3} and temperature 100-1000 K, and the relative abundances of CO:OH:H2O in the emitting region are 100:1:7 for a temperature of 200 K. The presence of a significant column of warm H2O suggests that the chemistry has been significantly changed by the shock. The existence of significant column densities of both OH and H2O, which is at odds with models for non-dissociative shocks into dense gas, could be due to photodissociation of H2O or a mix of fast and slow shocks through regions with different pre-shock density.Comment: AASTeX manuscript and 4 postscript figure

Measurement of enhanced ductility in nanolayered ceramics via micro-compression testing and digital image correlation

The use of ceramic or intermetallic structures in industrial applications is limited by their brittleness. However, it has been shown that nanolayered ceramics, such as the MAX phases, show unusually high levels of plasticity, with resolved shear yield stresses being reported to be as low as 77 MPa [1]. Our aim is to show that the origin of this behaviour is related to electron density shifts between layers, which enable eased dislocation movement compared to non-layered ceramics [2]. For an accurate study of this effect, and to prove its generality, a reliable determination of the onset of plastic deformation in form of dislocation movement is crucial. Please click Additional Files below to see the full abstract

Structural investigation of homonuclear Pt2 and heteronuclear PdPt complexes containing a metal-metal bond bridged by hydrido and sulfido ligands

The complex [Pt2(/.t-H)(#-S)(dppe)2](PF6) undergoes a displacive order-disorder transformation at ca 230 K. The low-temperature structure is ordered with one cation-anion pair as the asymmetric unit in space group P2Jn. At room temperature the b axis is halved and the space group is P2/n, imposing crystallographic twofold rotation symmetry on both ions; the anion shows major disorder and there is probably minor disorder in the cation, but its internal geometry remains essentially unchanged. The heteronuclear complex [PdPt(ft-H)(/.t-S)(dppe)2](PF6) is isostructural with the Pt2 complex at room temperature. All three structures have been determined crystallographically and both complexes have been extensively characterized by NMR spectroscopy, unambiguously confirming the genuine heteronuclear nature of the mixed-metal complex and the presence of the bridging hydride ligand

Using coupled micropillar compression and micro-Laue diffraction to investigate deformation mechanisms in a complex metallic alloy Al13Co4

In this investigation, we have used in-situ micro-Laue diffraction combined with micropillar compression of focused ion beam milled Al13Co4 complex metallic alloy to study the evolution of deformation in Al13Co4. Streaking of the Laue spots showed that the onset of plastic flow occured at stresses as low as 0.8 GPa, although macroscopic yield only becomes apparent at 2 GPa. The measured misorientations, obtained from peak splitting, enabled the geometrically necessary dislocation density to be estimated as 1.1 x 1013 m-2