Advanced Silicon Chemistry in Australia: Forming Strong Links with Asia.

This paper details Australian commercial and academic silicon research. Areas of interest include silicon metal, polysiloxane polymers, copolymers, cyclics, emulsions, microemulsions, silanes, silane coupling agents, sol-gel chemistry and water-treatments, porous silicon, polysiloxane degradation, silicon hydrogel contact lenses, silanolate synthesis, siloxane interfacial polymerisation, hydrosilylation, polysiloxane electrolytes for lithium ion batteries, silanes for PBX materials, octafunctionalized polyhedral oligomeric silsesquioxanes (POSS), POSS hybrids, sol-gel hydrogenation catalysts, silane modification of silica, sol-gel energy storage, silicate grout stabilisation, GeoPolymer concretes, aerogel insulating foams, "Phaco-Ersatz" Accommodating Gel-Intraocular Lens technologies. Strong collaborative opportunities, in silicon, with Asia, exist with organisations such as: 1) The Asian Silicon Society and 2) The Agency for the Assessment and Application of Technology (BPPT) Indonesia.

Inhibition of atherosclerotic lesion development in the ApoE-/- mouse by a novel β-oxa polyunsaturated fatty acid.

Recent findings that a novel polyunsaturated fatty acid, β-oxa 23:4n-6, inhibits adhesion molecule expression on vascular endothelial cells and leukocyte adhesion led us to examine its ability to inhibit the development of atherosclerosis in the apoE-deficient (apoE) mouse. The mice were kept on normal chow or a high-fat/high-cholesterol diet for various periods and treated with either vehicle or β-oxa 23:4n-6 by the intraperitoneal route. The hearts and aortae were isolated and lesion development at the aortic root was determined.

Gas-phase facial diastereoselectivity of equatorial and axial 4-chloro-adamant-2-yl cations.

The acid-catalyzed addition of CH3(18)OH to 2-methylene-adamantanes bearing a chlorine atom in the 4-equatorial (1e) or 4-axial (1a) position has been investigated in the gas phase, at 760 Torr, in the 40-120 degrees C temperature range. Two different experimental approaches were employed: (1) by adding neutral CH3(18)OH to the 2-methyl-4-Cl-adamant-2-yl cation, generated by protonation of the corresponding 2-methylene-4-Cl-adamantane (the extracomplex reaction) and (2) by reaction of 2-methylene-4-Cl-adamantane with CH3(18)OH2+, generated by methylation of H2(18)O (the intracomplex reaction). The crucial role of the nature of the noncovalent intermediates involved along the reaction coordinates emerges from the difference between the results obtained in the extracomplex and intracomplex reactions for both substrates investigated.

Gas-phase diastereoselectivity of secondary 5-substituted (X)-adamant-2-yl (X = F, Si(CH(3))(3)) cations.

Secondary 5-X-adamant-2-yl cations IX (X = F, Si(CH3)3) have been generated in the gas phase (total pressure = 760 Torr) from protonation-induced defluorination of epimeric 2-F-5-X-adamantanes 1X and their kinetic diastereoselectivity toward CH318OH investigated in the 40-160 degrees C range. The experimental results indicate that the facial selectivity of IX is insensitive to the composition of the starting 1X epimers as well as to the presence and the concentration of a powerful base (N(C2H5)3). This kinetic picture, supported by B3LYP/6-31G* calculations, is consistent with a single stable pyramidalized structure for IX, that is, (Z)-5-F-adamant-2-yl (I(Z)F) and (E)-5-Si(CH3)3-adamant-2-yl cations (I(E)Si).

A novel beta-oxa polyunsaturated fatty acid downregulates the activation of the IkappaB kinase/nuclear factor kappaB pathway, inhibits expression of endothelial cell adhesion molecules, and depresses inflammation.

Several novel polyunsaturated fatty acids (PUFAs) that contain either an oxygen or sulfur atom in the beta-position were found to exhibit more selective antiinflammatory properties than their natural PUFA counterparts. One of these, beta-oxa-23:4n-6, unlike natural PUFAs, lacked ability to stimulate oxygen radical production in neutrophils but caused marked inhibition of agonist-induced upregulation of leukocyte adhesion to cultured human umbilical vein endothelial cells (HUVEC) and E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 expression. In addition, beta-oxa-23:4n-6 inhibited acute and chronic inflammatory responses in mice as well as the upregulation of adhesion molecule expression in arterial endothelium.

Polar substituent effects in the bicyclo[1.1.1]pentane ring system: acidities of 3-substituted bicyclo[1.1.1]pentane-1-carboxylic acids.

Experimental gas-phase acidities are reported for a series of 3-substituted (X) bicyclo [1.1.1]pent-1-yl carboxylic acids (1, Y = COOH).

Importance of entropy in the diastereoselectivity of 5-substituted 2-methyladamant-2-yl cations.

The diastereofacial selectivity of 2-methyl-5-X-adamant-2-yl cations IX (X = CN, Cl, Br, CH3O, COOCH3, C6H5, CH3, and (CH3)3Sn) toward methanol has been investigated in the gas phase at 750 Torr and in the 40-120 degrees C temperature range and compared with that of IF (X = F) and ISi (X = (CH3)3Si) measured previously under similar conditions. Detailed analysis of the energy surface of the IMe (X = CH3) ion reveals that the activation barrier of its syn addition to methanol is significantly lower than that of the anti attack. In the 40-100 degrees C range, such a difference is strongly reduced by adverse entropic factors which are large enough to invert the IMe diastereoselectivity from syn to anti at T > 69 degrees C.

Inhibition of neutrophil leukotriene B4 production by a novel synthetic N-3 polyunsaturated fatty acid analogue, beta-oxa 21:3n-3.

We recently reported the synthesis and anti-inflammatory properties of a novel long chain polyunsaturated fatty acid (PUFA) with an oxygen atom in the beta-position, beta-oxa-21:3 n-3 (Z,Z,Z)-(octadeca-9,12,15-trienyloxy) acetic acid). Our data, from studies aimed at elucidating the mechanism of its action, show that pretreatment of human neutrophils with the beta-oxa-PUFA substantially depresses the production of leukotriene B(4) (LTB(4)) in response to calcium ionophore, A23187, comparable to standard leukotriene inhibitors such as zileuton and nordihydroguaiaretic acid. Interestingly, the n-6 equivalent, beta-oxa 21:3 n-6, is also a strong inhibitor of LTB(4) production.

Solvolysis of (Z)-5-trimethylstannyl 2-adamantyl p-bromobenzenesulfonate: mechanistic implications of a record-breaking secondary alpha-deuterium kinetic isotope effect for an SN1 substrate.

The secondary alpha-deuterium kinetic isotope effect (alpha-kie) for the solvolysis of (Z)-5-trimethylstannyl 2-adamantyl p-bromobenzenesulfonate in 97% w/w aqueous 2,2,2-trifluoroethanol (97T) at 25 degrees C has been measured (k(H)/k(D) = 1.33). The alpha-kie is abnormally high compared to the value of 1.

Diastereofacial Selectivity in Atom Transfer Reactions of 5-Substituted (X) Adamant-2-yl Radicals: Nature of the Electronic Factor.

The diastereofacial selectivity in deuterium and halogen atom abstraction reactions of 5-fluoro- and 5-(trimethylstannyl)-2-adamantyl radicals has been investigated. Significant preferential syn (or zu) and anti (or en) face selectivity, respectively, is observed for these substituents of distinctly opposite electronic character. Although the observations are in accord with predictions from Cieplak's transition state hyperconjugation model, an alternative explanation can be advanced based on an early reactant-like TS model.