Magnetization of Yeast by Labeling with Iron Complexes: An Undergraduate Laboratory Experiment

This undergraduate laboratory experiment is designed for first-year general chemistry students with the goal of introducing the brilliant colors and magnetic properties of transition metal complexes within a bioinorganic/cell biology context. In the first laboratory period, a coordination complex formed from ferric chloride and maltol is prepared (Fe(maltol)3). The intense red color of the complex is noted, and the UV-vis spectra of the ligand and complex are compared. Yeast cells are incubated with ferric chloride and with Fe(maltol)3. In the second laboratory period, the yeast cells treated with the ferric chloride or Fe(maltol)3 are isolated and placed over ring magnets to study whether the yeast have paramagnetic properties. Yeast viability studies are done to compare the toxicity of Fe(maltol)3 and FeCl3. Students are asked to predict the magnetic properties of iron complexes of different spin and oxidation states and to consider the basis for iron uptake into yeast cells.