Covalently Attached Monolayers on Hydrogen-Terminated Si(100): Extremely Mild Attachment by Visible Light

摘要

A holy grail in the attachment of monolayers on surfaces involves the use of ambient conditions that are compatible with a wide variety of functional groups. Such conditions would, for example, allow for the direct covalent attachment of many bioactive materials to a surface. In the field of covalently attached monolayers to well-defined Si surfaces presently reported attachment methods include thermal conditions and UV irradiation. Although such reaction conditions yield stable and densely packed monolayers, they are too harsh to allow the use of labile bioactive materials. This situation has two ways out: In the first route, one attaches a precursor to the surface that can stand such harsh conditions, which is subsequently transformed into the bioactive monolayer. Such an approach has been taken by, for example, Hamers and co-workers, and in the elegant DNA attachment studies of Horrocks, Houlton and co-workers. The second route would make use of mild reaction conditions that are, in principle, compatible with such bioactive moieties. In the case of porous silicon, such an approach has been taken by Buriak and Stewart through either the use of a white-light-promoted reaction or a hydride-abstracting agent. Recently, Hamers reported the visible light (514 nm)-initiated modification of flat Si(111) and Si(001) surfaces by partial iodination.