Corroles are aromatic compounds consisting of four pyrrole-like subunits connected in a ring via three methane bridges and one direct bond between the alpha carbons of two of the subunits. They have a structure and photophysical properties similar to that of porphyrins, which are currently being researched in blocking tumor progression and metastasis. In photosynthetic bacteria, tetrapyrrolic molecules are used in the light harvesting complexes to channel solar energy towards the reaction complex where photosynthesis occurs. Similar to porphyrins, corroles demonstrate exceptional photophysical properties in regards to their absorbance of light and fluorescence. Corroles exist in two separate tautomeric states, causing them to exhibit noticeably different photophysical and electrochemical behaviors in different solvents. A proper understanding of the interactions between corroles and solvents, and how these interactions affect corroles' light absorbing emitting capabilities, is necessary to develop potential uses of corroles in artificial photosynthetic devices, petroleum explorations, cancer diagnosis, and tumor treatment. We investigated the photophysical, electrochemical, and spectroelectrochemical properties of free-basetriphenylcorrole (H3TPCor). We have characterized corroles ability to absorb light in various solvents and in a multitude of concentrations. We have also characterized the excited state emission of H3TPCor and the role of solvent in the lifetime of the same excited state. UV-Visible data show a trend indicating that the transition from one tautomer to another is dominated by the H-bonding donating ability of the solvent molecules with the core of H3TPCor. One automer shows four oxidation potentials in the electrochemistry experiments, while the other shows three oxidation potentials. Both tautomers have only one reduction potential. UV-Visible spectra of reduced H3TPCor species all followed the same trend. The results indicate that the reduced species prefers this form irrespective of the solvent used. When oxidized, H3TPCor’s spectrum resembles the spectrum of the most stable tautomer. We have also characterized the free-base corrole with electron withdrawing and donating groups. Preliminary results have shown that H3TPCor and the functionalized corrole have several properties with many similar trends in regards to the solvent effect in the tautomerization equilibrium.

Photophysical, electrochemical, and spectroelectrochemical characterization and solvent effect on the tautomerism of free-base corrole

255th National Meeting (2018)

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