Researcher(s)
- Cecilia Delgado, Biochemistry, University of Delaware
Faculty Mentor(s)
- Joel Rosenthal, Chemistry and Biochemistry, University of Delaware
Abstract
Porphyrins exhibit magnetic and optical behaviors that allow them to be used as magnetic sensors for analytic techniques and as optical isolators for high-powered lasers or fiber optics. This is due to their magneto-optical activity (MOA), which indicates that a compound or material can rotate linearly polarized light in the presence of a magnetic field. MOA can be quantitatively determined through the measurement of magnetic circular dichroism (MCD). This is completed on site at the Rack Lab at the University of New Mexico. Qualitatively, MOA in porphyrins can be estimated by features in the absorbance spectrum. Porphyrins have three characteristic bands in the UV-vis region: one large Soret band near 400 nm, and two smaller Q-bands (Q1 and Q0) around 600 nm. The ratio of MCD to absorbance is the key to MOA, and this ratio is greater at the Q-bands than the Soret band. Previous work by the Rosenthal and Rack Labs led to the discovery that peripheral substituents on porphyrin structures strongly affect the MOA when bound to group 10 metals. Changes in symmetry by using two distinct substituents also show a trend correlated with the number of electron-withdrawing groups attached, rather than an immediate loss of MOA as a result of breaking symmetry. To observe what occurs to MOA when symmetry is further broken, a novel porphyrin with three distinct peripheral substituents will be prepared by modular synthesis. The porphyrin will have C6F5 (pentafluorophenyl) at the C5 and C10 position, C6H4(CF3)2 (bis-3,5-trifluoromethylphenyl) at the C15 position, and C6H5 (phenyl) at the C20 position. Once synthesized, the free base will be metalated with Zn2+ and Pd2+, and absorbance spectroscopy will be completed to observe the changes in the Q-bands.