Fluorescence is the energy emitted in the form of light previously absorbed by the substance. The wavelength of the emitted light is longer than the wavelength of the absorbed light. Substances, that have the ability to emit energy in this form, have multiple conjugated double bonds (e.g., aromatic rings) in their structure – called fluorophores. In the course of his master's thesis, Andraž Bevk inadvertently isolated a fluorophore, which in its structure is most similar to polymethine dyes or more accurate to cyanine dyes. In the first part of the study, we tried to synthesize fluorophores from similar skeletons. We were interested in influence of the starting compounds and the solvent. Arylacetonitrile and ethyl arylacetate were used as starting compounds. In both cases, synthesis was successful. In the case, where ethyl arylacetate was used as starting compound, the cyclization of the resulting product, which was also fluorescent, occurred. In the following, we tried to synthesize the fluorophores from two different arylacetonitriles, but the products were not created. Two different solvents were used for the syntheses: dimethylformamide and N,N-dimethylacetamide. For all three resulting products (1, 9, 13), dimethylformamide was used, which is based on the fact, that the carbon atom from dimethylformamide was required to bond the two starting compounds. Lastly, we tried the alkylation of fluorophores, so that we could bind different functional groups onto them. Alkylation was unsuccessful. In the second part, we used ultra-high performance liquid chromatography for determination of synthesis yields of products (1, 9, 13). First, we selected the method and optimal conditions for the separation. Next, we determined a wavelength for each product, where sensitivity and selectivity of the method were the highest. At the selected wavelength, the chromatogram of the product solution with linear range of concentration was recorded. At each concentration, the area under the curve was read from the chromatogram. Next a graph of the dependence of area under the curve from the fluorophore concentration was plotted from the obtained data. A line equation was obtained, from which the concetration and later yield of synthesis of individual products were calculated. Finally, the fluorescence spectrum was recorded. The type of aromatic system certainly has an effect on the excitation and emission spectrum, but due to the small number of compounds prepared, the relationship between structure and photo-physical properties cannot yet be well described.
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