The interaction between carbon dioxide (CO2) and N-compounds such as 1,8-diazobicyclo[5.4.0]undec-7-ene (DBU) has been extensively studied in the Jessop Lab. Carbon disulfide (CS2) is the sulfur congener of CO2, although it exhibits different reactivity with N-containing compounds. This thesis presents the search for zwitterionic CO2-switchable polarity solvents, new and general reactivity of CS2 with amidines and guanidines, and attempts at using CO2 as a carbonyl source in the synthesis of nitrogen containing compounds. In the second chapter, the reactions of CO2 with various diamines are described. Spectroscopic methods and X-ray crystallography determined the structure of a solid zwitterionic carbamate salt of CO2 and N,N’-dimethyl-1,3-propanediamine. The polarity of the liquid zwitterionic carbamate salt formed with N,N,N’-trimethyl-1,3-propanediamine was measured using UV-Vis and the solvatochromic dye Nile red; its polarity was comparable to previous switchable polarity systems. The CO2 gravimetric uptake of the liquid zwitterionic carbamate salt was 28%, far greater than other solvents for the capture and release of CO2. In the third chapter, it was found that a variety of products can be accessed depending on the structure of the N-base (cyclic or acyclic) upon reaction of the base with CS2 at room temperature. The reaction of CS2 with cyclic amidines produced a cyclic trithioanhydride structure, forming a new C-C bond at a sp2-carbon beta to the imino nitrogen centre. When an amidine was acyclic it led to cleavage and formation of isothiocyanates in near quantitative yields. When a N-base had a N-H bond, CS2 can insert, forming a dimer in the presence of dichloromethane. In the fourth chapter, preliminary investigations are ascribed for synthesis of α-amino acids, amides, and ureas. Carboxylation of ketimines was detected, although the formed carboxylates from a variety of ketimines readily decomposed. Isomerization products of two ketimines were generated with DBU and CO2. Lewis acid catalysts were implemented towards the amidation of benzoylacetic acid and synthesis of ureas. Amidation of benzoylacetic acid did not occur in the presence of Lewis acid catalysts and CO2. Formation of a cyclic tetraalkylurea was afforded in low yields by the use of a diamine, CO2 and Lewis acid catalysts. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-12-01 19:16:55.257

In this thesis, we investigate biological molecules on a micron scale in the ultraviolet spectral region through the non-destructive confocal absorption microscopy. The setup involves a combination of confocal microscope with a UV light excitation beam to measure the optical absorption spectra with spatial resolution of 1.4 μm in the lateral and 3.6 μm in the axial direction. Confocal absorption microscopy has the benefits of requiring no labels and only low light intensity for excitation while providing a strong signal from the contrast generated by the attenuation of propagating light due to absorption. This enables spatially resolved measurements of single live cells and bio-molecules with less than 10^9 molecules in the probe volume. Employing a multichannel detection system, the absorption spectrum of hemoglobin in a single red blood cell is measured on the timescale of seconds. We also extend the spectral range from the visible range to the experimentally more challenging ultra-violet region where characteristic absorption bands of bio-molecules are observed. Exploiting the ultra-violet range, amino acids, nucleic acids solutions, and plant cells are investigated. We measure the spatially resolved absorption spectra at the nucleus of an onion cell and cytoplasm to probe DNA base-pair absorption. Small variations in our micro-absorption data are seen around 260 nm, possibly due to the abundance of DNA in the nucleus. This thesis contributes to the goal of spectroscopic identification of spatial heterogeneities at the single cell level and the label-free detection of proteins and nucleic acids.