Structural characterization of organic multilayers on silicon(111) formed by immobilization of molecular films on functionalized Si-C linked monolayers

Silicon(111)-H surfaces were derivatized with omega-functionalized alkenes in UV-mediated and thermal hydrosilylation reactions to give Si-C linked monolayers. Additional molecular layers of organic compounds were coupled either directly or via linker molecules to the functionalized alkyl monolayers. In the first instance, amino-terminated monolayers were prepared from a tert-butoxycarbonyl-protected omega-aminoalkene followed by removal of the protecting group. Various thiols were coupled to the monolayer using a heterobifunctional linker, which introduced maleimide groups onto the surface. In the second system, N-hydroxysuccinimide (NHS) ester-terminated monolayers were formed by reaction of Si-H with N-succinimidyl undecenoate. The reactivity of the NHS ester groups was confirmed by further modification of the monolayer. The stepwise assembly of these multilayer structures was characterized by X-ray reflectometry and X-ray photoelectron spectroscopy.