Two copper complexes of tripodal ligands derived from the amino acids cysteine and methionine were synthesized and shown to act as a molecular switches through redox-mediated metal ion control of the ligand conformation. Two ether/thioether ligands were studied that showed markedly different behavior from previous examples involving carboxylate and alkoxyl coordination. The ligand chirality, nearly absent in the cysteine case except for substitution of sulfur for oxygen atom in one arm, is amplified after metal complexation, and can be reconfigured between two propeller forms on electron oxidation/reduction. The complex derived from cysteine shows very different CD spectral properties from the previously reported one, revealing an interesting structure in solution. In addition, the circular dichroism spectrum of the Cu(II) complex from methionine derivative was observed to be inverted in different solvents (methanol and acetonitrile). Zinc analogs of the complexes were also synthesized for <sup>1</sup>H NMR studies of the coordination chemistry in these solvents.

Copper(I/II) reconfiguration of ligand conformations: Amplification and control of helicity by a single atom and solvent

253rd National Meeting (2017)

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