While azoalkanes are normally employed as convenient sources of radicals and biradicals, radical cation salts such as tris-(4-bromophenyl)aminium hexachloroantimonate and thianthrenium perchlorate oxidize azoalkanes under mild conditions to products characteristic of alkyl cations. A survey of N$\sb2$ yields for oxidation of twenty azoalkanes was conducted to compare their reactivity. Detailed product studies were conducted on selected azoalkanes in order to derive a general mechanism and to rationalize the effect of azoalkane structure on reactivity. A slower secondary decomposition observed for both azo-t-octane and 3,3,6,6-tetramethyl-1,2-diazacyclohexene was attributed to an oxidant containing the anion of these radical cations. Replacement of these "oxidizing" anions (SbCl$\sb{6\sp-}$, ClO$\sb{4\sp-}$) with "non-oxidizing" anions (SbF$\sb{6\sp-}$, BF$\sb{4\sp-}$) prevented the secondary decomposition of these azoalkanes. Tertiary azoalkanes that form an unstrained radical and cation reacted with two equivalents of radical cation salt affording a quantitative yield of N$\sb2$ and two equivalents of cation-derived products. For bridgehead azoalkanes, the N$\sb2$ yield decreased as the strain in the incipient radical and cation increased, an effect attributed to diversion of the more reactive radicals from oxidation to hydrogen abstraction. Cis to trans isomerization of azo-1-norbornane was observed with a catalytic amount of radical cation, but no N$\sb2$ was lost even when the radical cation was in two-fold excess. Replacement of an "oxidizing" anion with a "non-oxidizing" anion in the reaction of a radical cation with azo-1,1$\sp\prime$-adamantane warrants the reinvestigation of this reaction which involved the "oxidizing" anion. Rather than losing N$\sb2$, 2,3-diazabicyclo (2.2.2) oct-2-ene formed a red salt with the radical cation, but replacing both bridgehead hydrogens with methyl groups again led to N$\sb2$ loss. The analogous compound with only one bridgehead methyl group exhibited both N$\sb2$ loss and adduct formation. The reactivity of an azoalkane was shown to depend upon its structure as well as the structure of its incipient alkyl cation. An electrophilic mechanism was favored over a single electron transfer mechanism because oxidation of azoalkanes by these radical cation salts appears to be endothermic.

The new third form of carbon, known collectively as fullerenes, is studied in several general aspects. Efficient production methods have been developed along with an increased understanding into the formation mechanisms. Several physical and chemical properties are investigated in attempts to characterize these unique molecules. An exciting feature of these all-carbon molecules is their ability to undergo chemical modification while maintaining their cage structure, unlike diamond or graphite. One of the fundamental alterations is the addition of oxygen atoms to the cage. Techniques to produce these derivatives and their characterization is also presented.

Herein is described the synthesis and assembly of compounds designed to advance the fields of surface science and molecular electronics. The first series of compounds are based on a phenanthrene core and are terminated with a thioacetate moiety which allows for assembly onto metallic surfaces. Eight polyaromatic compounds were synthesized to examine the role of internal rotation in electrical switching as observed by a scanning tunneling microscope (STM). It was thought that internal rotation, which disrupts the molecule's conjugation, was responsible for the switching behavior. One of these polyaromatic compounds (2-thioacetyl-phenanthrene) as well a biphenyl control (4-thioacetobiphenyl) were examined in a STM testbed. The polyaromatic compound (which cannot rotate) showed switching allowing internal rotation to be ruled out as a mechanism for switching as seen by STM. A second series of compounds, organic thiocyanates, were synthesized to examine their assembly onto metallic surfaces. It was found that this class of compounds assembles onto metallic surfaces under ambient conditions. The resultant monolayer contains the same thiolate-gold bond seen when assembling from the free thiol. The mechanism for this assembly involves surface-mediated conversion of the thiocyanate to a thiolate and M(CN)ads followed by expulsion of the cyanide from the surface as a metal salt ([M(CN) 2]- or [M(CN)4]2-). Comparable free thiol assembles are oxidatively unstable and are prone to disulfide formation. In the case of alpha,o-dithiols, polymerization is often seen. Thiocyanates are advantageous as they are stable and require neither exogenous material for the assembly nor oxygen free conditions. Finally, a series of transition metal complexes designed to assemble on gold surfaces was synthesized. This bis(2,5-di-[2]pyridyl-3,4-dithiocyanto-pyrrolate) metal complex was prepared with zinc, copper, nickel, cobalt, and iron. The electronic structure and transitions of these compounds were studied by UV-vis and their magnetic properties studied by EPR and SQUID magnetometer. These molecules were then assembled onto a gold surface taking advantage of the above thiocyanate assembly protocol. The assembly process gives a loosely packed monolayer with no sign the compound had disproportionated or decomposed. This molecular assembly was used in single molecule transistors (SMTs) and allowed for examination of the Kondo effect.

The objectives of this research were to study metabolic pathways in C. roseus hairy root cultures, and to enhance secondary metabolite productivity using fungal elicitation as the technique. The effects of age of inoculum were studied by adapting the cultures to three subculture cycle routines. The 2 week subculture cycle yielded the fastest, while the 4 week cycle yielded the lowest, specific growth rates. Specific yields of tabersonine decreased from day 21 to 35 while the total yields of horhammericine increased in all three subculture cycles. Lochnericine yields were highest in the 2 week cycle while serpentine yields were lowest. The effects of dosages and exposure times of specific elicitors on several compounds in the indole alkaloid pathway were studied. A 150% increase in tabersonine specific yield was observed upon addition of 72 units of pectinase. Levels of serpentine, tabersonine and lochnericine decreased transiently after addition of pectinase in time course studies. Jasmonic acid was found to be a unique elicitor leading to an enhancement in flux to several branches in the alkaloid pathway. Time course studies with jasmonic acid showed a transient increase in lochnericine and tabersonine levels and a continuous increase in levels of ajmalicine, serpentine and horhammericine. NMR spectroscopy was utilized as the tool to study primary metabolism of hairy roots non-invasively. $\sp{31}$P NMR spectroscopy studies indicated that vacuolar and cytoplasmic pH were maintained at 7.4 $\pm$ 0.06 and 5.25 $\pm$ 0.08 respectively. $\sp{13}$C NMR spectroscopy studies indicated activities of pentose phosphate pathways, non-photosynthetic CO$\sb2$ fixation and glucan synthesis pathways. Recycling of triose phosphate was evident from scrambling of label in glucans. In vivo $\sp{31}$P and $\sp{13}$C NMR spectroscopy was subsequently utilized to study the effects of elicitors on primary metabolism. A transient short-term decline in the cytoplasmic pH was observed upon addition of pectinase while a prolonged decrease in vacuolar pH was observed upon addition of jasmonic acid. Enhanced accumulation of glucans was detected upon addition of pectinase. A reduction in the levels of pyruvate and glutamine was observed, upon addition of jasmonic acid, indicating a decrease in flux to glycolysis or an increase in the drain on these pools.

A new widely tunable mid-infrared (IR) source based on difference-frequency generation (DFG) in Gallium Selenide (GaSe) for use in high-resolution spectroscopy and trace gas detection is described. The characteristics of type-I phasematching in GaSe are studied. Preliminary results on the improvement of the dispersion relations for GaSe are presented. Spectroscopic feasibility experiments are reported that involve the spectroscopy of ethylene $\rm (C\sb2H\sb4)$ at low pressures near 950 $\rm cm\sp{-1}.$ Two near-IR Ti:Sapphire lasers served as convenient pump sources, which can be eventually replaced by two high power near-IR diode lasers. Design issues (including optimum elliptical focusing conditions), potential improvements and new directions are also discussed.

Applications taking advantage of fluorine-fluorine interactions for separations are a recent analytical trend, with benefits in terms of cost, ease of use and specificity cited as advantages of these so-called “fluorous” techniques. While most current fluorous separations employ columns packed with microspheres, columns based on entrapped microspheres, porous polymer monoliths (PPMs) and open tubes all represent viable alternatives to conventional packed capillaries. In this thesis, the design, optimization and implementation of fluorous stationary phases based on all three of these new technologies are explored. Development of methods and techniques using these systems are presented, with factors affecting their performance being examined. Doing this, the specificity of the fluorous interaction can also be explored, and potential applications for these new materials can be discussed. For the work with entrapped microspheres, the columns that were formed did not prove to have an advantage over those that were unentrapped. Although affixing spheres within a matrix is known to have benefits in terms of bed stability over repeated use, the inclusion of a polymer coating proved to represent a greater concern for the availability of the bead-based stationary phases. Layers of polymer forming over the surface were shown to limit the access of analytes to the entrapped microspheres, restricting the usefulness of these materials. The work with fluorous monoliths proved the most successful, providing clear evidence of improved selectivity when compared to analogs made without fluorination. Fluorous retention specificity was also effectively examined, with secondary effects probed and compared to those that had been discussed for commercially-available fluorous microspheres. Results showed that the monoliths were very much in-line with what had already been seen for sphere-based systems, with residual substrate character providing only a slight contribution to the observed separations. Finally, development of open-tubular columns based on microstructured optical fibers was the most speculative of the projects discussed here. The introduction of a fluorous stationary phase through silanization was demonstrated to be an effective method for imparting chromatographic selectivity into these columns, and controllable factors such as treatment protocol and silane character were shown to affect the performance of the resulting materials. / Thesis (Ph.D, Chemistry) -- Queen's University, 2011-05-06 17:03:14.803

This dissertation presents solid-state NMR studies of the chain conformation, dynamics and morphology of three adsorbed polymer systems: two random semi-crystalline copolymers, poly(ethylene-co-acrylic acid) (PEA) and poly(propylene-co-acrylic acid) (PPA), and an amorphous homopolymer, poly(n-butyl methacrylate) (PnBMA). Zirconia (ZrO2) was chosen as the substrate for all three polymers since the binding of carboxylic acids to this metal oxide is well understood. The choice of polymers was based on their particular bulk conformational and dynamic properties as well as their common use in polymer coatings. These studies are motivated by the general lack of a microscopic picture of adsorbed polymers, which can be provided by NMR, and the relevance of chain conformation and dynamics to important polymer film properties such as adhesion. / First the chain conformation and surface binding of adsorbed PEA as a function of acrylic acid content are characterized by 13C cross polarization - magic angle spinning (CP-MAS), 2D 1H- 13C wideline separation (WISE) and 1H spin diffusion NMR experiments and FTIR-PAS (Fourier transform infrared photoacoustic spectroscopy) measurements. The most important finding is that the chain conformation of adsorbed PEA is determined primarily by the sticker group density rather than the surface coverage. The second study of PEA concerns the chain dynamics in the bulk and adsorbed states. Variable temperature NMR experiments provide evidence that ethylene segments of adsorbed PEA form partially folded loops rather than flat extended trains. Finally 129Xe NMR studies, used to probe the morphology of adsorbed PEA, show a bulk-like signal only for the highest loadings. / The second system investigated, PPA, is another semi-crystalline random copolymer which binds to zirconia via carboxylate linkages. The 13 C CP-MAS NMR spectra of adsorbed PPAC unexpectedly show splittings normally associated with chain-chain packing in the crystalline regions of bulk polypropylene (PP). The splittings in the spectra of adsorbed PPAC, which are more resolved than in bulk PPA, are proposed to arise from recrystallization of the PP segments between sticker groups. / Finally the interfacial properties of an amorphous homopolymer, PnBMA were studied using 13C and 129Xe NMR to characterize adsorbed and filled samples. PnBMA binds to zirconia via the partial hydrolysis of the ester side chains. The remaining ester chains of adsorbed PnBMA are found to segregate to the polymer/air interface. Both adsorbed and ZrO 2-filled PnBMA show enhanced local segmental mobility. However, the 129Xe NMR measurements of the filled samples are consistent with restricted motion on a larger length scale which may be due to particle bridging.

A new type of confocal Raman microscope called a Fourier transform confocal Raman microscope (FT-CRM) was designed, built and characterized with respect to its spatio-spectral imaging properties. Several different applications of the FT-CRM are presented that take advantage of its unique spectral and spatial imaging characteristics. The instrument combines focused illumination with spatially-filtered detection in a confocal optical configuration to collect photons scattered from a diffraction-limited volume in the sample (typically ${<}5 times10 sp{-18} m sp3)$ and reject photons from outside that region. The molecular vibrational information encoded in the inelastic, or Raman, spectral component of light scattered from the confocal volume is measured with a visible light Fourier transform Raman spectrometer. By scanning the sample relative to the confocal volume, a volumetric Raman spectrochemical image of the sample can be constructed. / Raman scattering is an inherently inefficient process; hence an optimal radius pinhole must be found that balances the FT-CRM optical throughput against the microscope spatial resolution and image contrast. Detailed experimental measurements mapped out the FT-CRM spatial response (axial and lateral), optical throughput and image signal-to-background and signal-to-noise ratios as a function of pinhole radius. Excellent agreement was found between these measurements and the predictions of a theoretical microscope model also developed as part of this thesis. Several applications of the FT-CRM included volumetric compositional imaging of three-dimensional chemically inhomogeneous materials such as cellulose and polyester fibers in water or two immiscible optically-similar liquids, water and trichloroehthylene, in a porous quartz sandstone matrix. The potential of the FT-CRM for non-invasive spectrochemical detection and imaging through a turbid tissue-like medium was demonstrated and a new spectral estimator, Fast Orthogonal Search, was evaluated to replace the discrete Fourier transform to improve the microscope performance.

High pressure infrared and micro-Raman vibrational spectroscopy has been used to study the following organoplatium(II) complexes: Zeise's salt, K (Pt($ eta sp2$-C$ sb2$H$ sb4$)Cl$ sb3$); Zeise's dimer, (Pt($ eta sp2$-C$ sb2$H$ sb4) sb2$Cl$ sb2 rbrack sb2$; and dichloro(1,5-cyclooctadiene)platinum(II), Pt(COD)Cl$ sb2$. Pressure dependences of the vibrational modes have been used in the assignments of the $ upsilon$(C=C) modes and the ethylene and cyclic diene C-H stretching vibrations. Pressure increases the extent of $ pi$-backbonding, as shown by the negative pressure dependence of the $ upsilon$(C=C) stretching frequencies.

A thickness-shear mode (TSM) acoustic wave sensor system has been constructed and used to examine binding phenomena that occur in the liquid phase. The work is broadly divided into two sections. / The first section examines the use of cholestyramine as a sensor coating for detection of bile acids. A 10-MHz piezoelectric crystal is coated on one side with cholestyramine resin and mounted in a batch-mode sensor block which exposes the coating to solution. After sample injection, the binding process is observed in real time as a drop in frequency as the bile salt binds to the coating, reaching >90% completion within 10 minutes with most of the binding occurring within the first minute. Linear calibration curves are generated with sensitivity increasing in the order cholate &ap; glycocholate < taurocholate << taurodeoxycholate. Detection limits in water are in the range 0.2--9 nmol and are better than those observed in phosphate buffer. A multi-step regeneration protocol allows the coating to be reused more than 400 times over a period of several months. Precision for replicate injections is about 10% RSD and depends on the reproducibility of the regeneration and injection steps. / In terms of the binding process, hydrophobic interactions are observed to be of importance in the ability of bile salts to displace other counterions. However, anions with greater charge density also appear to compete effectively for binding sites on the resin. In particular, at equimolar concentrations of citrate and bile salt, the trivalent citrate anion reduces the amount of bile salt binding by about 40%. This suggests that the efficiency of cholestyramine-based bile salt sequestering drugs used in the reduction of hypercholesterolemia may be improved by eliminating citric acid as an excipient and avoiding the use of fruit juices during ingestion. / In the second section, a selection of compounds were examined for their potential as stable and reactive liquid-phase coatings with the primary amine group as the functional group of interest. Based on dry TSM sensor frequency changes, all coating candidates exhibited some degree of stable coating formation after incubation and rinsing. Reactivity of the coatings was then assessed via reaction with succinic anhydride under anhydrous conditions. With pyridine- and thiol-based coatings, the frequency change is negligible or is positive, which may indicate some loss of coating material upon reaction of the amine group. A silane-based coating was stable but exhibited only small frequency decreases for the reaction step. In terms of stability, reproducibility and magnitude of the frequency changes observed, poly(ethyleneimine) (PEI) is seen to be the best choice for providing analytically useful signals where covalent reaction with surface-confined amino groups in the liquid phase is desired. / Reaction of PEI with succinic anhydride also serves as a method for fabrication of sensor coatings with the carboxylic acid group as the reactive functional group of interest. The formation of reactive COOH groups was tested with a carbodiimide-activated covalent immobilization of dopamine. TSM sensor frequency changes, ellipsometry, and x-ray photoelectron spectroscopy provided support for all steps involved. The coating surface structure is uneven and is likely highly branched and three-dimensional. The method is quick and simple, and the films are also sufficiently robust for liquid-phase acoustic wave sensor applications.