Heterogeneous Mixture of Amino Acids and Self-assembly on Metal Surfaces
Authors:
- Students:
- Madeline Chorazy
- Andrew Cook
- Luis Hernandez
- Colin Shea
- Cody Summerson
- Rachel Ward
- Teachers:
- Jeff Newton
- Irina Stan
- Mentors:
- Nathan P. Guisinger (Argonne National Laboratory, Center for Nanoscale Materials)
Center for Nanoscale Materials
In this study, novel atomic-scale exploration of molecular self-assembly of the chiral amino acid proline and tryptophan on Cu(111) was demonstrated. This research aimed to further the knowledge and understanding about how L-proline and L-tryptophan self-assemble, noting how chirality affects their interactions. Homochiral samples of both L-tryptophan and L-proline on a Cu(111) surface were individually explored, as well as a racemic (50-50) mixture. A scanning tunneling microscope was used to map the self-assembly at a clear molecular resolution. This experiment was performed in an ultrahigh vacuum to avoid interference from outside particles. By analyzing the results, it was found that L-proline forms molecular trimers as base units that assemble into larger hexagonal tilings. Similarly, L-tryptophan forms molecular trimers on base units that assemble into long chains. There was also findings of individual molecules within the hexagonal tiling of proline. The findings for the L-tryptophan and L-proline racemic mixture were found inconclusive.