ChiralCreating Crystallization a Conference and Epitaxial Poster Materials John Z. Tubbesing, Avishek Banik, AuthorsBin Luo, orXiaoting ReserachersZhang, Meagan Kelso, & Jay A. Switzer Department of Chemistry and Graduate CenterDepartment for Materials or Research, Organization Missouri University of Science and Technology, Rolla, Missouri 65409-1170, United States Why Epitaxy Matters Epitaxial Materials Preliminary Chiral Crystallization Cuprous Iodide was epitaxially Epitaxial [epi (ἐπί) – above; taxis (τάξις) – deposited on silicon (111). Due to

an ordered layer] means that the crystallite growth of a SiOx layer between orientation of the deposited film is directed the substrate and film, the by the substrate on which it is deposited. resultant CuI film may be peeled off (top). If a film is deposited epitaxially upon a Chiral metal surfaces of gold single-crystal substrate, the epitaxial film will (643) were deposited on silicon exhibit fewer grain boundaries which leads to (643) wafers (bottom).3 improved characteristics. Tellurium was unsuccessfully deposited on Si (111). It peeled NaClO3 spin coated onto L-cysteine self assembled monolayer Because the crystallization is affected by (right, video). (SAM) viewed through a polarized light microscope at +45° (left) substrate-solute interactions, this may be Attempts were made to and -45° (right). Crystals of the same handedness rotate light the useful for selectively crystallizing a particular epitaxially deposit the following: same direction. Although this one area showed enantiopure crystals, more species from a mixed solution. • Benzyl, Benzophenone, NaCLO3 on cysteine SAM on Au (111). work is needed to determine how and why this happens. • Zinc sulfide, telluride, and Additionally, on other samples and on other areas of this sample, selenide on silicon (111) crystals rotated light the opposite way. • Copper selenide and telluride Additionally, +/- Camphor was sublimated onto the L-cysteine Why Chirality Matters on silicon (111) SAMs, however these proved to be too difficult to characterize. • Copper and copper(I) thiocyanate on 1,2-ethane diol Chiral compounds (molecules with nonsuperimposable mirror SAM on gold (111) images), especially pharmaceuticals, represent a 100-billion-dollar • Bismuth, bismuth telluride, and industry worldwide.1 Because chiral molecules are foundational to Conclusions bismuth selenide on silicon life as we know it, many biological processes are enantiospecific. (111) The most infamous example of chirality affecting our world was • Lead on gold (111) the chiral drug Thalidomide, whose R enantiomer was effective Completed Work against morning sickness and popularly sold as a sedative, but • Cuprous Iodide manuscript – An epitaxial, peelable, whose D enantiomer led to birth defects in over 10,000 children.2 Chiral Electrochemistry Towards Crystallization optically transparent hole conducting film on silicon As science advances, new chiral drugs are and will be developed (111). which will not be able to take advantage of traditional • Grew a textured film of benzyl on L-cysteine SAM enantioselective methods such chiral pool synthesis. A new 643 “A” 643 “B” on Au (111) on Si (111). separation method for enantiomers must be developed. Future Work • DOPA oxidization on 643 surfaces which have

electrical contacts directly to the surface. DOPA

- • Continued work on benzyl films for epitaxy of L organic molecules • Tellurium deposition on SAM or silicon • Epitaxial electrodeposition of metal-organic

frameworks (Cu-BTC)

DOPA - D References (1) STINSON, S. C. COUNTING ON CHIRAL DRUGS. Chem. Eng. The four graphs on the left show a battery of cyclic voltammograms for oxidization of D/L-DOPA on epitaxial gold on silicon News Arch. 1998, 76 (38), 83–104. https://doi.org/10.1021/cen- (643). The figure on the right is an idealized rendition of a (643) or (6̅4̅3̅) surface.3 Note how the two surfaces are v076n038.p083. Acknowledgements nonsuperimposable mirror images of each other. “A” and “B” represent opposite sides of a Si (643) wafer. X-ray diffraction may (2) Vargesson, N. Thalidomide-Induced Teratogenesis: History be performed to determine whether “A” corresponds to (643) or (6̅4̅3̅). and Mechanisms. Birth Defects Res. Part C Embryo Today Rev. This material is based on work supported by the US It appears that L-DOPA interacts with “A” 643 without other reactions, while L-DOPA has side reactions or less reactivity with 2015, 105 (2), 140–156. https://doi.org/10.1002/bdrc.21096. Department of Energy, Office of Basic Energy Sciences, Division the “B” surface. When using D-DOPA, the situations are perfectly reversed: the “B” side of the Si (643) is favorable, while the (3) Kelso, M. V.; Tubbesing, J. Z.; Chen, Q.; Switzer, J. A. Epitaxial of Materials Sciences and Engineering, under Grant No. DE-FG02- “A” side is other reactions. Electrodeposition of Chiral Metal Surfaces on Silicon(643). J. Am. 08ER46518. Due to sample degradation and issues creating electrical contacts, this work has not been repeatable. Chem. Soc. 2018, 140 (46), 15812–15819. Special thanks to Dr. Eric Bohannan for help with Xray diffraction https://doi.org/10.1021/jacs.8b09108.