Precise Molecular Fission and Fusion: Quantitative Self‐Assembly and Chemistry of a Metallo‐Cuboctahedron

Inspiration for molecular design and construction can be derived from mathematically based structures. In the quest for new materials, the adaptation of new building blocks can lead to unexpected results. Towards these ends, the quantitative single‐step self‐assembly of a shape‐persistent, Archimedean‐based building block, which generates the largest molecular sphere (a cuboctahedron) that has been unequivocally characterized by synchrotron X‐ray analysis, is described. The unique properties of this new construct give rise to a dilution‐based transformation into two identical spheres (octahedra) each possessing one half of the molecular weight of the parent structure; concentration of this octahedron reconstitutes the original cuboctahedron. These chemical phenomena are reminiscent of biological fission and fusion processes. The large 6 nm cage structure was further analyzed by 1D and 2D NMR spectroscopy, mass spectrometry, and collision cross‐section analysis. New routes to molecular encapsulation can be envisioned.     

A wall sub-model in KIVA3 for the prediction of transient exhaust HC concentrations

Unburned fuel is one of three main pollutants from spark ignition internal combustion engines. The mechanisms of escape of this fuel from the main combustion event have been well studied. However, while up to 10% of the main chamber fuel may escape the initial combustion phase, 80–90% of this is oxidized during the postflame period. Modelling of this oxidation requires a detailed understanding of heat and mass transfer in the boundary layer on the surfaces of the combustion chamber. The resolution of the temperature and concentration gradients requires cell sizes less than 0.1 mm. This means that the processes may not be directly estimated with standard computational fluid dynamics (CFD) representations of combustion. In addition, combustion in the vicinity of the wall is usually quite different from that in the main chamber. A one-dimensional (1D) wall model for the oxidation of HCs was implemented into the wall cells of a KIVA3 computational model. The wall layer was used to follow the postfame oxidation of HCs during the expansion stroke. The CFD model was retained to predict combustion, quench and boundary conditions for the wall model, and to follow the entrainment, mixing and oxidation of HCs throughout the exhaust stroke. This paper describes the model. It presents some of the results of the model in the prediction of various features of interest within the processes of postflame oxidation. Most importantly it allows the prediction of mixing and entrainment of HCs from the exhaust gases in the exhaust stream. A comparison of the predictive capabilities of the model with some experimental HC traces is also presented.     

The Hodge structure of the coloring complex of a hypergraph

Let G be a simple graph with n vertices. The coloring complex Δ(G) was defined by Steingrímsson, and the homology of Δ(G) was shown to be nonzero only in dimension n−3 by Jonsson. Hanlon recently showed that the Eulerian idempotents provide a decomposition of the homology group H_n−3(Δ(G)) where the dimension of the jth component in the decomposition, , equals the absolute value of the coefficient of λ^j in the chromatic polynomial of G, χ_G(λ).Let H be a hypergraph with n vertices. In this paper, we define the coloring complex of a hypergraph, Δ(H), and show that the coefficient of λ^j in χ_H(λ) gives the Euler Characteristic of the jth Hodge subcomplex of the Hodge decomposition of Δ(H). We also examine conditions on a hypergraph, H, for which its Hodge subcomplexes are Cohen–Macaulay, and thus where the absolute value of the coefficient of λ^j in χ_H(λ) equals the dimension of the jth Hodge piece of the Hodge decomposition of Δ(H). We also note that the Euler Characteristic of the jth Hodge subcomplex of the Hodge decomposition of the intersection of coloring complexes is given by the coefficient of jth term in the associated chromatic polynomial.     

Nakijinamines C-E, new heteroaromatic alkaloids from the sponge Suberites species

Three new heteroaromatic alkaloids, nakijinamines C-E (1-3), which are a hybrid of the aaptamine-type and bromoindole alkaloids possessing a taurine- or histidine-derived residue, have been isolated from an Okinawan marine sponge Suberites species. The structures of 1-3 were elucidated on the basis of spectroscopic data and chemical conversions. Nakijinamines C (1) and E (3) are the first natural products possessing a 1H-oxazolo[4',5':4,5]benzo[1,2,3-de][1,6]naphthyridine ring system.     

Hyrtioseragamines A and B, new alkaloids from the sponge Hyrtios species

Two novel alkaloids with a furo[2,3-b]pyrazin-2(1H)-one moiety and a guanidino group, hyrtioseragamines A (1) and B (2), have been isolated from an Okinawan marine sponge Hyrtios species. The structures of 1 and 2 were elucidated on the basis of spectroscopic data and chemical conversions. Compounds 1 and 2 are the first natural products possessing a furo[2,3-b]pyrazine-related moiety.     

Addition of arylboronic acids to arylpropargyl alcohols en route to indenes and quinolines

A regio- and stereoselective rhodium-catalyzed synthesis of trisubstituted allylic alcohols is described. The utility of these synthons is demonstrated in a convenient synthesis of indenes and quinolines.     

Kinase inhibitory, haemolytic and cytotoxic activity of three deep-water sponges from North Western Australia and their fatty acid composition

The c-AMP dependent protein kinase (PKA) inhibition, haemolytic activity, and cytoxicity of 21 extracts obtained from North Western Australian sponges collected from depths of 84-135 m were investigated. Hexane extracts from Ircinia/Sarcotragus sp. and Geodia sp. displayed PKA inhibitory activities of 100 and 97% respectively (at 100 microg/mL), while aq. methanol extracts from Haliclona sp. exhibited potent haemolytic activity (75%) and hexane extracts from Geodia sp. were highly toxic (88%) to the brine shrimp Artemia franciscana. As the non-polar extracts gave the greatest PKA inhibition, these were further analysed by GC-MS and 29 fatty acids were identified in the highest proportions in Ircinia/Sarcotragus sp. > Haliclona sp. > Geodia sp. In contrast to shallow-water sponges that are dominated by polyunsaturated fatty acids with a high percentage of long chain fatty acids, LCFAs (C24-C30), the deep-sea sponges investigated herein were all found to be rich in saturated fatty acids, in particular C14-C20 fatty acids, including odd and branched chain fatty acids, with only low levels (0-10%) of LCFAs. Screening of the PKA inhibitory activity of a series of commercially available fatty acids identified C14-C18 fatty acids as possessing significant PKA inhibitory activity that may contribute to the activity observed in the sponges studied.     

Videographic Documentation of an Open Cyst Converting Into a Sulcus Vocalis

Study Design

Case study.

Discussion

The origin of sulcus vocalis is debatable, it may arise from a congenital or acquired cyst that ruptures leaving a sulcus attached to the deep layer of the lamina propria. This has been hypothesized but never shown before.

Conclusion

In this article, we present the first videographic documentation of an intracordal cyst that over time may have become a sulcus vocalis.     

Poly(pyrazolyl)aluminate complexes containing aluminum-hydrogen bonds

The treatment of LiAlH(4) with 2, 3, or 4 equiv of the 3,5-disubstituted pyrazoles Ph(2)pzH or iPr(2)pzH afforded [Li(THF)(2)][AlH(2)(Ph(2)pz)(2)] (97%), [Li(THF)][AlH(Ph(2)pz)(3)] (96%), [Li(THF)(4)][Al(Ph(2)pz)(4)] (95%), and [Li(THF)][AlH(iPr(2)pz)(3)] (89%). The treatment of ZnCl(2) with [Li(THF)][AlH(Ph(2)pz)(3)] afforded Zn(AlH(Ph(2)Pz)(3))H (70%). X-ray crystal structures of these complexes demonstrated κ(2) or κ(3) coordination of the aluminum-based ligands to the Li or Zn ions. The treatment of [Li(THF)][AlH(Ph(2)pz)(3)] with MgBr(2) or CoCl(2) in THF/Et(2)O solutions, by contrast, afforded the pyrazolate transfer products Mg(2)Br(2)(Ph(2)pz)(2)(THF)(3)·2THF (25%) and Co(2)Cl(2)(Ph(2)pz)(2)(THF)(3)·THF (23%) as colorless and blue crystalline solids, respectively. An analogous treatment of [Li(THF)][AlH(Ph(2)pz)(3)] with MCl(2) (M = Mn, Fe, Ni, Cu) afforded metal powders and H(2), illustrating hydride transfer from Al to M as a competing reaction path.     

Inorganic chemistry and IONiC: an online community bringing cutting-edge research into the classroom

This Viewpoint highlights creative ways that members of the Interactive Online Network of Inorganic Chemists (IONiC) are using journal articles from Inorganic Chemistry to engage undergraduate students in the classroom. We provide information about specific educational materials and networking features available free of charge to the inorganic community on IONiC's web home, the Virtual Inorganic Pedagogical Electronic Resource (VIPEr, www.ionicviper.org ) and describe the benefits of joining this community.