A Short and Efficient Synthesis of the [3]Triangulene Ring System

Triangulenes are of current interest for potential applications in molecular electronics. We describe here a three step synthesis of the 4,8,12‐trihydro[3]triangulenium cation by cascade cyclization of a tetra‐benzyl alcohol precursor in triflic acid solution. This stable carbocation is easily observed by NMR and optical spectroscopy and is highly fluorescent. Quenching of the cation into basic solutions or by hydride transfer from triethylsilane provides access to stable dihydro and tetrahydro[3]triangulenes. These neutral species interconvert with cations in a complex series of proton and hydride transfers. This route provides several important [3]triangulene precursors. Preliminary experiments designed to generate [3]triangulene in the solution phase provide evidence for its formation and rapid oligomerization.     

The diffraction of elastic waves by an imperfect fusion bond

We consider diffraction by a semi-infinite crack located alonga fusion interface between two differing elastic media. Twotypes of crack, namely open and partially closed cracks, areinvestigated. An open crack is modelled by a stress-free contactboundary condition and a partially closed crack is modelledby a spring contact boundary condition. For the latter, thejump in the stress across the crack is assumed to be proportionalto the jump in the displacement across the crack. This situationarises in, for example, a K-weld where the fine grain of theparent material (for example, ferritic or forged austeniticsteel) is in stark contrast with the coarse-grained weld metal(for example, austenitic weld metal). In the metal weld thedirection of the grain axis varies through the metal. However,diffraction is a local phenomenon and so the austenitic steelis assumed to have a zonal axis so that it may be modelled bya transversely isotropic composite. The ferritic or forged austeniticsteel will be modelled as an isotropic material.     

The asymptotics of the Arakelov-Geen's function and Faltings' delta invariant

We study the behavior of the Arakelov-Green's function and Faltings' delta invariant on degenerating Riemann surfaces.Supported in part by an Alfred P. Sloan Doctoral Dissertation Fellowship     

A high-swelling reagent scaffold suitable for use in aqueous and organic solvents

A polymeric scaffold with excellent swelling properties in organic and aqueous environments is highly desirable for the medicinal chemist. Here, we demonstrate that a cross-linked polyacrylamide hydrogel that displays large swelling properties in both organic solvent and water can serve as a scaffold for the photosensitizer hematoporphyrin. Upon exposure to light, the resulting resin efficiently generates singlet oxygen which can then react with appropriate substrates.     

The integrability criterion in SU(2) Chern-Simons gauge theory

We prove that the multiplicity spaces appearing in Chern-Simons theory, as defioned by Segal, vanish unless they are associated to integrable representations. This and other links with conformal field theory are examined.Supported in part by NSF Mathematics Postdoctoral Fellowship DMS-9007255     

Analysis of perfluoroalkanes and fluorobenzenes using an Al2 O3 porous-layer open-tubular column

Summary Many of the isomers of fluorocarbons have boiling points which are less than one degree different. Thus it is necessary to use some other basis for their separation on a chromatographic column. One such possibility is gas-solid chromatography. It has been demonstrated that an alumina porous-layer open-tubular (PLOT) column is especially well suited for the analysis of fluoroalkanes and fluorobenzenes. This column is useful for the specific application of the measurement of electron attachment properties of these molecules using the electron-capture detector because of thelack of column bleed.     

Developing soluble polymers for high-throughput synthetic chemistry

Soluble polymers have emerged as viable alternatives to resin supports across the broad spectrum of high-throughput organic chemistry. As the application of these supports become more widespread, issues such as broad-spectrum solubility and loading are becoming limiting factors and therefore new polymers are required to overcome such limitations. This article details the approach made within our group to new soluble polymer supports and specifically focuses on parallel libraries of block copolymers, de novo poly(styrene-co-chloromethylstyrene), PEG- stealth stars, and substituted poly(norbornylene)s.