Capturing Molecules in an Iron Cage
Mentor:David Vosburg, Associate Professor of Chemistry, Harvey Mudd College
Host-guest chemistry of self-assembling complexes is an active research area with many potential applications. The Nitschke group at the University of Cambridge developed a self-assembling “iron cage” that is soluble in water and capable of trapping non-polar molecules. This cage can disassemble under acidic conditions, allowing for selective release of captured guest molecules. The goal of the experiment was to adapt the iron cage assembly and guest capture as an experiment for a 2nd semester organic chemistry curriculum. The cage formation was tested at room temperature and with microwave heating, and used cyclohexane and dioxane as guest molecules. Purification methods included crystallization, pipet filtration, and no purification. The host-guest cage complexes were analyzed using 1H-NMR spectroscopy in D2O, displaying a dramatic chemical shift change for captured guest molecules. The reaction emphasizes green chemistry, as it is performed in a single step at room temperature in water from commercial reagents. This self-assembly and guest capture experiment has been tested at Harvey Mudd College and is appropriate for use with undergraduates at other institutions.