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The syntheses of many cycloalkene and cycloalkeneone annelated DHPs have been achieved. A late ring formation approach was used to synthesize the dicycloalkeneone annelated DHP 63 (Scheme 4) and the unsymmetrical dicycloalkeneone annelated DHPs 70a and 70b (Scheme 5). To synthesize the other ring annelated DHPs, a more versatile early ring approach was employed. Through an asymmetrical coupling followed by a series of standard transformations, the cyclopentene-, cyclohexene-, cyclopentenone- and cyclohexenone-annelated DHPs 64 , 118 , 130 , 131 were synthesized (Schemes 13 and 15). Similarily, the dicycloalkene and dicycloalkenone annelated DHPs such as 41 , 42, 123, 124 and 136 were obtained by a symmetrical coupling followed by a series of standard transformations (Schemes 12, 14 and 16). Other than the cycloalkene or cycloalkenone annelated DHPs, the acyclic tetra-substituted DHPs 142 and 143 (Scheme 17) were also synthesized as model compounds. As well, the asymmetrical DHPs 148 and 149 (Scheme 18), having a benzene and a cyclopentenone annelation or with a benzene and a cyclopentenone annelation, were also synthesized to test the annelation effect with a combination of a benzene and a five-membered ring. In the cycloalkene and cycloalkenone annelated DHP series, it was demonstrated that the [pi]-bond fixation effect could be indirectly probed by the internal methyl proton chemical shifts. These are based on the ring current of DHP and the magnitude of bond fixation depends on the annelating ring size, the coplanarity of the carbonyl group with the [pi]-system of DHP (for the cycloalkenone annelated DHPs) and the relative arrangement of the annelated rings (cisoid versus transoid for the diannelated compounds). Thus, when the ring size varied from four to seven in the cycloalkene- and dicycloalkenene annelated DHP series, the cyclohexene ring has the strongest bond fixation effect. When the ring size varied from five to seven in the cycloalkenone- and the dicycloalkenone-annelated DHP series, the cyclopentenone annelated DHPs have the strongest bond fixation effect. In the mono-cycloalkenone annelated DHP series (ring size =5 to 7), the Kekulé structures of the cycloalkenone annelated DHPs were determined by the vicinal coupling constant (3Jhh) to adopt an endocyclic structure (the double bond appears at the ring junction between the DHP and the annelating ring). For the diannelated DHP derivatives, the cisoid arrangement of ring annelation always has a stronger bond fixation effect compared to that of a transoid arrangement in almost all cases. In this thesis work, the use of DHP as a sensitive NMR probe was successfully demonstrated in that its internal methyl proton chemical shift responds to a change of ring current caused by different ring annelations. It is so sensitive, that even the very small perturbation on ring annelation (by cycloalkanes) can be sensed. DHP is a better NMR probe molecule than benzene because the chemical shifts of the internal methyl protons of DHP are less seriously affected by any effects such as geometrical distortion, rehybridization, steric compression, hyperconjugation and through space effects as probed by the ¹H and ¹³C-NMR spectroscopies in benzocycloalkenes. The ring annelation effect probed by DHP is closer to a pure [pi]-effect due to a change in ring current which is different from benzene, which is a mixture of both α- and [pi]-effects... / Graduate

The work described in the thesis is concerned with making new polymeric materials via ring opening metathesis polymerisation (ROMP) using a well-defined ruthenium carbene as an initiator. The object of the study was to provide a process for producing shaped articles by introducing a reactive liquid mixture into a mould in which the reacting liquid mixture undergoes ROMP in the bulk to produce the moulded article. Mono- and difunctional imidonorbomene derivatives were used as monomer and crosslinker respectively. The properties of the cured samples were determined by sol-gel analysis, DSC, TGA, nmr and IR spectrometry. Gel fraction, Tg and content of unreacted monomer were used to characterise the cured samples. The results indicated a strong dependence of the polymers appearance and properties on the polymerization formulation and protocol, i.e. the monomer, the crosslinker and the polymerization conditions. The relative reactivity of the exo- and endo-monomers was investigated using the 'Hnmr technique since the initiation and propagation steps of the polymerisations can be followed in detail by this technique. The results showed that the polymerisations are living and the exo-isomer is more reactive than endo-isomer. A wider range of polymers can be prepared from solution polymerisation as compared to bulk polymerisation. The polymers derived from solid monomers, the monofunctional monomer with short N-alkyl pendant groups and all the difunctional monomers, could be prepared more easily in solution than in bulk polymerisation. The endo-monomer and the monofunctional monomer with long N-alkyl pendant group showed very low reactivity and were not suitable for ROMP in bulk but underwent solution polymerisation. It was found that the thermal properties of the linear polymers depend upon the amount of each monomer isomer incorporated into the polymer chain and the ength of the N-alkyl pendant groups. All linear polymers are soluble in chlorinated solvents from which clear films can be cast. The work described establishes conditions for production of fully crosslinked solids with only traces of the sol fraction.

Call number: LD2668 .T4 1951 T76 / Master of Science

Let D be an integral domain and f a polynomial that is integer-valued on D. We prove that Int(f(D);D) has the Skolem Property and give a description of its spectrum. For certain discrete valuation domains we give a basis for the ring of integer-valued even polynomials. For these discrete valuation domains, we also give a series expansion of continuous integer-valued functions. / by Mario V. Marshall. / Thesis (Ph.D.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.

by Jian-hui Liu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (p. 112-118). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

This thesis presents a detailed study of chip based silicon photonic waveguide technologies for chemical sensing applications. The project specifically focuses on the use of strip and slot waveguide based micro-ring resonators (MRRs) integrated with graphene and graphene oxide (GO) as potential functional sensor coatings. The primary objective is to understand the effect of graphene/GO on the optical properties of such a device, to assess performance in bio-/chemical sensing applications and to identify ways in which such a device may be optimised. A detailed analysis of how the MRR cavity optical extinction ratio (ER) varies with the interaction length of surface integrated graphene reveals, for the first time using this technique, the in-plane graphene linear absorption coefficient, αgTE = 0.11 ± 0.01dBμm⁻¹. A model of the MRR cavity optical losses for different graphene lengths and heights (above the waveguide surface) provides a predictive capability for the design rules of optimised performance in sensing and photo-detector based applications. The graphene integrated MRRs were also characterized by a Raman mapping technique from which careful analysis of the graphene G and 2D scattering peak frequencies and relative intensities revealed that the graphene is electrically intrinsic where it is suspended over the MRR yet moderately hole-doped where it sits on top of the waveguide structure. This 'pinning' of the graphene Fermi level at the graphene-silicon/SiO2 interface is the result of 'trapped' ad-charges, the concentration of which may be increased at dangling bond sites after relatively aggressive (O2 plasma) cleaning of the silicon/SiO2 surface prior to graphene transfer. Quantifying this substrate doping effect is critically important when attempting to determine graphene's optical properties and should be taken into account when designing graphene-silicon hetero-structures for opto-electronic devices. The large absorption coefficient determined for the graphene integrated MRR devices means that cavity losses are far too high for practical realisation of refractive index based sensing. However, an alternative approach using GO as the functional layer for improved MRR based refractive index sensors remains a possibility on account of the much lower transmission loss. GO also has distinct advantages over graphene; ease of integration, a high density of surface functional groups and micro-porosity. Transmission spectral analyses of both bare (uncoated) MRRs and those coated with different GO concentrations revealed the in-plane linear absorption coefficient for the GO film to be αGOTE = 0.027±0.02dBμm⁻¹, which is much lower than that for graphene. Construction of a gas cell and integrated 'bubbler' arrangement for delivering variable vapour concentrations to the graphene/GO integrated MRR devices under test is presented. Both bare and GO coated MRRs were exposed to vapours from a series of typical organic solvents; ethanol, pentene and acetone delivered by a carrier gas (N2). Dynamic optical tracking of the MRR cavity resonance wavelength during vapour exposure, at different flow rates (vapour concentrations) reveals the sensitivity of the device(s) to small changes in refractive index. The dynamic response of the GO coated MRRs to the vapours were up to three times faster than the uncoated MRR with similar improvements in sensitivity and limit of detection, largely attributable to the porous nature and molecular binding affinity of the GO. Critically, these experiments reveal that the detection sensitivity and response of the GO is solvent dependent, which may mean that it is capable of providing a degree of selectivity, which is normally difficult to achieve in refractive index based gas sensing.