Tuning Molecular Binding Configurations of Pyridine on Si(111)-(7×7) via Surface Modification

Abstract

To prepare functional molecular templates for the development of hybrid molecular devices, multifunctional molecules may be employed and attached onto the silicon surfaces. Due to their possible multiple binding configurations, it is challenging to achieve the exclusive selectivity for the desired configuration. In this paper we describe a feasible way to tune the binding mechanism of pyridine through the coadsorption of pyrrole on the Si(111)-(7×7) surface at room temperature. Our X-ray photoelectron spectroscopy and high-resolution electron energy spectroscopy results clearly demonstrate that pyridine bonds to the clean Si(111)-(7×7) surface in the configuration of 1,4-cyclohexadiene-like adducts on the surface via Si−C(N) di-σ-linkages. However, on pyrrole-precovered surfaces, pyridine molecules are dative-bonded to the remaining adatoms on the surface. This fine-tuning of molecular configuration via surface premodification provides flexibility in controlling the molecular attachment on silicon surfaces.

Molecular chemisorption on passivated and defective boron doped silicon surfaces: a “forced” dative bond

“…The most stable model is M4 in which the molecule is perpendicular to the surface. In agreement with different authors, 32,40 the nitrogen lone-pair electrons of the pyridyl part of the PAB molecule interacts with the Si adatom in models M2, M3 and M4. This interaction is more effective when the molecule is perpendicular to the surface (M4 model) and, to a lesser extent, tilted (M3 model).…”

“…M1 and M4 models are the most stable ones in agreement with theoretical results obtained for the pyridine molecule adsorbed on Cu(110) and Ag(110) surfaces. 32,40 Concerning the M1d, M2d, M3d and M4d models, we notice that the boron defect stabilizes the four models. The models M2d and M3d present a similar adsorption energy despite different adsorption configurations.…”

“…Previous studies have already shown dative bond formation between a pyridine molecule and different semiconductor surfaces such as Si(001), 73 Si(111)7 Â 7 (ref. 74) or Ge(100). 75 In all cases, the authors have demonstrated that the pyridine molecules are dative-bonded to the electrondeficient silicon atoms of the surface.…”

“…The authors conclude that the pyridine molecules could interact with Si(001) through Si-down-lone-pair electrons of the N atom allowing a dative bonding. Furthermore, as presented by Zhang et al, 74 the pyridine adsorption on the Si(111)7 Â 7 surface have been studied by means of X-ray photoelectron spectroscopy and high-resolution electron energy spectroscopy. The authors showed the formation of a dative bond between the N-atom of pyridine and the corner adatom as well as the high thermal stability of this dative-bonded pyridine at room temperature.…”

Molecular Nanocorrals on Si(111)-(7×7): Temperature-Dependent Site Selectivity

“…With most center adatoms being reacted and darkened, the unreacted corner adatoms are isolated and form hexagonal circle arrays surrounding the corner holes (Figure d). These highly ordered and isolated atomic circles remain reactive toward the further adsorption and reaction, possibly serving as a potential template for future nanolithography . The darkened corrals trapping surface electrons may also be employed as building blocks for molecular electronics or a model system to study the size-confinement of electrons …”