Perylene-3,4,9,10-tetracarboxylic diimide (PDI) has emerged as a building block of organic materials for next generation molecular electronics. Intensely absorbing and chemically robust, PDI-based materials often excel as n-type semiconductors in organic field-effect transistors and organic photovoltaic (OPV) cells. Notably, twistacene nanoribbons arising from the iterative fusion of PDI to ethylene have been incorporated into OPV cells with power conversion efficiencies approaching 10%. These PDI-twistacenes adopt various unresolvable isoenergetic conformations in solution, precluding the possibility of optical activity. In pursuit of persistent helical chirality in PDI-based nanoribbons, I have prepared and now present naphthyl- and anthracenyl-linked PDI-dimer helicene (NPDH and APDH). Their syntheses entail the cross-coupling of an acene to two PDI subunits, followed by oxidative ultraviolet cyclizations. Straining the polyaromatic surface does not encumber the efficiency of these photocyclizations: they proceed quantitatively, without a trace of the sterically favored regioisomers. We have resolved NPDH and APDH into their constituent enantiomers by chiral high performance liquid chromatography. Solutions of APDH racemize at room temperature, whereas NPDH does not invert at 250 °C. The enantiostability of NPDH arises from the extensive intramolecular overlap of its π-surface. Looking down its stereogenic axis reveals ten pairs of π-bonded atoms eclipse one another. The nearest of these pairs are separated by 3.2 Å, closer than twice the van der Waals radius of the carbon atom. Thus, the naphthyl link of NPDH facilitates intramolecular π-to-π collisions between the PDI subunits. Voltammetric, spectroelectrochemical, and EPR measurements suggest these π-to-π collisions enable through-space electronic delocalization when NPDH is reduced. I next report the preparation of a π-helix of helicenes constituted from three PDI monomers and two naphthalene subunits. Two different synthetic routes of alternating cross-couplings and oxidative photocyclizations provided this nanoribbon, naphthyl-fused PDI-trimer helix (NP3H). Remarkably, visible light from household lightbulbs induces these cyclizations, although the final cyclization proceeds more swiftly when on the helix exterior than when within its core. NP3H possesses extraordinary chiroptical properties, exhibiting numerous and incredibly intense electronic circular dichroism (ECD) across the UV-visible range (|Δε| = 820 M-1 cm-1 at 407 nm). The ECD spectrum of NP3H transforms significantly in the presence of a mild reducing agent and visible light. Spectroelectrochemical measurements confirmed that photoinduced electron transfer to the π-helix tunes its absorbance of circularly polarized light.

Includes bibliographical references (p. 155-159).

Diastereomers of CpRh{C(O)Me}(P*)I, (P* (TBOND) (S)-Ph(,2)PNHCH(Me)Ph), have been prepared and separated. Decarbonylation with AgBF(,4) gave a single diastereomer of CpRhMe(CO)(P*)(.)BF(,4) and subsequent treatment of the salt with anions likewise gave single isomers of CpRh{C(O)Me}(P*)X (X = Cl, Br, I, SCN, NCS). The high stereospecificity of these transformations is attributed to the ability of the acyl ligand to undergo stereospecific reversible decarbonylation such that the methyl group occupies the site vacated by the iodide ligand, i.e., inversion. Addition of N(,3)('-) and MeO('-) to the salt resulted in the stereospecific formation of CpRhMe(P*)X' (X' = NCO, COOMe). Metathesis of CpRh{C(O)Me}(P*)Cl with I('-) proceeded with retention of configuration at rhodium. / The chiral complexes (1-C(,9)H(,6)Cl)Rh(COD), (COD (TBOND) 1,5-cyclooctadiene), and (1-C(,9)H(,6)X)Mn(CO)(,3), (X = Cl, Br, I) have been synthesized via diazoindene insertion. Only the pentahapto bonding mode has been detected for these complexes. / Photochemical and chemical decarbonylation of trans-CpFe(CO)(,2){C(O)CH=CHR}, (R = Ph, Me), proceeded with retention of geometry about the double bond to give trans-CpFe(CO)(,2){CH=CHR}.

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No description available.

In this thesis, we study the "two-point approximation" for highly non-local effective actions, in the particular case of the Chiral Soliton Model of the nucleon. The nucleon in this model is regarded as being made of three valence quarks bound together by a meson field in a soliton form. Mesons are treated in mean field theory and the vacuum energy due to one-quark loops is included. The theory is defined with a finite cut-off in momentum space, consistent with an effective theory for the low-energy description of the strong interactions. We use the two-point approximation to calculate the vacuum correction to the chiral soliton energy for a variety of soliton profile functions, investigating the effect of different regularisation schemes. Results are little influenced by the choice of the cut-off, and are within 20% of exact calculations, done with the full inclusion of the Dirac sea. We then perform a dynamical calculation of the chiral soliton by including sea-quark effects self-consistently in the two-point approximation. We find a typical 20% (or less) deviation in the soliton energy from exact calculations. We apply a further "pole" approximation which leads to a significant algebraic simplification in the self-consistent equations. We show, in particular, that a simple numerical fit of the pole form to the two-point cut-off function yields essentially indistinguishable results from the latter. We finally calculate some static nucleon observables in the two-point approximation and find general agreement with exact calculations. In view of the results obtained, we may hope that the pole form of the twopoint approximation may prove to be a generally useful approach to similar problems involving highly non-local actions.

Thesis (Ph.D.)--Michigan State University. Dept of Chemistry, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references. Also issued in print.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vii, 38 p. : ill. Includes abstract. Includes bibliographical references (p. 34-38).

Dissertation (Ph.D.)--Worcester Polytechnic Institute. / Keywords: supported catalyst; spin coating; atomic layer deposition; carbon nanotubes; model catalyst; ferrocene; thin film coating. Includes bibliographical references. (p.256-258)

Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 256-266).