Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces

Bibliographic Details
Main Author: Yuk, Simuck Francis
Language:English
Published: The Ohio State University / OhioLINK 2015
Subjects:
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=osu1428947746
id ndltd-OhioLink-oai-etd.ohiolink.edu-osu1428947746
record_format oai_dc
spelling ndltd-OhioLink-oai-etd.ohiolink.edu-osu14289477462021-08-03T06:30:02Z Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces Yuk, Simuck Francis Chemical Engineering Chiral Surfaces Adsorption Density Functional Theory Enantiospecificity Often, obtaining an enantiopure form of drugs is important in pharmaceutical industry since the biomolecules exist strictly as homochiral. Drugs based on undesirable form of enantiomer could bring disastrous consequences to their users. Naturally chiral metal surfaces, obtained from cleaving bulk metals, have shown to possess enantiospecificity (i.e. ability to distinguish enantiomers). The source of enantiospecificity of such surfaces is the presence of under-coordinated kink sites along the step edges. However, there are two primary drawbacks to chiral metal surfaces: (1) they present a relatively homogenous environment of a single metal which reduces the observed enantiospecficity, and (2) are expensive to produce as single-crystal surfaces.To further optimize and tailor the enantiospecificity of chiral surfaces, we study the enantiospecificity of Pt nanostructures grown on the step-kink edges of chiral SrTiO3 surfaces. Density functional theory (DFT), a quantum mechanics-based modeling method, is our primary tool to characterize the enantiospecificity of oxide-supported metal structures. The heterogeneous electronic structure of underlying oxide substrate is expected to optimize the enantiospecificity of grown metal nanostructures. Pt was chosen to grow metal nanostructures because of its close lattice match with SrTiO3.As a first effort to understand the electronic effects of oxide substrate, we studied the CO adsorption on the Pt monolayers (MLs) supported on the SrTiO3(100). We found that the nature of deposited Pt is heavily dependent on its underlying oxide atoms at the 1 ML of Pt. The different hybridization between Pt d valence and CO orbitals is mainly responsible for these oxide-dependent behaviors of deposited Pt. Such oxide effects diminish after depositing more than 2 ML of Pt on the SrTiO3 support.Next, the enantiospecific adsorption of R- and S-methyl lactate was investigated on the chiral Cu(643) surface. DFT-derived pre-factors along with desorption energies predict peak temperatures that are in relatively good agreement with temperature programmed desorption (TPD) studies for molecular desorption of methyl lactate from Cu(643) surface. The global minimum of S-methyl lactate is more firmly bound by 9.5 kJ/mol over its enantiomer on the Cu(643) surface, with a peak temperature difference of 25 K versus an experimental value of 12 K.We also studied the enantiospecific adsorption of R- and S-fluoroaminomethoxy on the Cu, Pd, and Pt(874)S surfaces. The different geometry and enantiospecific energy difference of global minima were observed when varying the type of surface metal. To understand the variation in enantiospecificity, the local binding model was adopted to analyze the adsorption energetics of chiral molecule. The model shows that large enantiospecificity occurs when each local bonding of functional group is distinctive between R- and S-global minima.Finally, the enantiospecific adsorption of R- and S-methyl lactate was studied on Pt thin films supported on chiral SrTiO3(643). Distinctive degree of enantiospecificity was obtained due to the different arrangement of underlying oxide atoms at the 1 and 2 ML of Pt, indicating the possibility of tailoring the enantiospecificity of deposited Pt metal structures. Again, such oxide effects subside after depositing more than 2 ML of Pt on the oxide support. 2015-05-19 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1428947746 http://rave.ohiolink.edu/etdc/view?acc_num=osu1428947746 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection NDLTD
language English
sources NDLTD
topic Chemical Engineering
Chiral Surfaces
Adsorption
Density Functional Theory
Enantiospecificity
spellingShingle Chemical Engineering
Chiral Surfaces
Adsorption
Density Functional Theory
Enantiospecificity
Yuk, Simuck Francis
Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces
author Yuk, Simuck Francis
author_facet Yuk, Simuck Francis
author_sort Yuk, Simuck Francis
title Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces
title_short Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces
title_full Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces
title_fullStr Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces
title_full_unstemmed Enantiospecificity of Chiral Pt Nanostructures Grown on Chiral SrTiO3 Surfaces
title_sort enantiospecificity of chiral pt nanostructures grown on chiral srtio3 surfaces
publisher The Ohio State University / OhioLINK
publishDate 2015
url http://rave.ohiolink.edu/etdc/view?acc_num=osu1428947746
work_keys_str_mv AT yuksimuckfrancis enantiospecificityofchiralptnanostructuresgrownonchiralsrtio3surfaces
_version_ 1719437907268206592