Tuning Molecular Binding Configurations Of Pyridine On Si(111)-(7x7) Via Surface Modification

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)-(7x7) 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)-(7x7) surface in the configuration of 1,4-cyclohexadiene-like adducts on the surface via Si C(N) di-sigma-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.