title: Controlling the stereochemistry and regularity of butanethiol self-assembled monolayers on au(111).
abstract: The rich stereochemistry of the self-assembled monolayers (SAMs) of four butanethiols on Au(111) is described, the SAMs containing up to 12 individual C, S, or Au chiral centers per surface unit cell. This is facilitated by synthesis of enantiomerically pure 2-butanethiol (the smallest unsubstituted chiral alkanethiol), followed by in situ scanning tunneling microscopy (STM) imaging combined with density functional theory molecular dynamics STM image simulations. Even though butanethiol SAMs manifest strong headgroup interactions, steric interactions are shown to dominate SAM structure and chirality. Indeed, steric interactions are shown to dictate the nature of the headgroup itself, whether it takes on the adatom-bound motif RS(•)Au(0)S(•)R or involves direct binding of RS(•) to face-centered-cubic or hexagonal-close-packed sites. Binding as RS(•) produces large, organizationally chiral domains even when R is achiral, while adatom binding leads to rectangular plane groups that suppress long-range expression of chirality. Binding as RS(•) also inhibits the pitting intrinsically associated with adatom binding, desirably producing more regularly structured SAMs.
authors.affiliation: Department of Chemistry, Technical University of Denmark , Kongens Lyngby 2800, Denmark.
authors.forename: Jiawei
authors.initials: J
authors.lastname: Yan
authors.forename: Runhai
authors.initials: R
authors.lastname: Ouyang
authors.forename: Palle S
authors.initials: PS
authors.lastname: Jensen
authors.forename: Erhad
authors.initials: E
authors.lastname: Ascic
authors.forename: David
authors.initials: D
authors.lastname: Tanner
authors.forename: Bingwei
authors.initials: B
authors.lastname: Mao
authors.forename: Jingdong
authors.initials: J
authors.lastname: Zhang
authors.forename: Chunguang
authors.initials: C
authors.lastname: Tang
authors.forename: Noel S
authors.initials: NS
authors.lastname: Hush
authors.forename: Jens
authors.initials: J
authors.lastname: Ulstrup
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Reimers
mesh_terms: D006046:Gold / Q000737:chemistry*; D050607:Organogold Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D011789:Quantum Theory; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D050607:Organogold Compounds; D013438:Sulfhydryl Compounds; D006046:Gold; C025540:n-butyl mercaptan