The surface as molecular reagent: organic chemistry at the semiconductor interface

Methods for the incorporation of organic functionality onto semiconductor surfaces have seen immense progress in recent years. Of the multiple methods developed, the direct, covalent attachment of organic moieties is valuable because it allows for excellent control of the interfacial properties. This review article will focus on a number of synthetic strategies that have been developed to exploit the unique reactivity of group-IV surfaces under vacuum. A picture of the semiconductor surface and its reactions will be developed within the standard framework of organic chemistry with emphasis on the importance of combined experimental and theoretical approaches. Three broad areas of organic chemistry will be highlighted, including nucleophilic/electrophilic, pericyclic, and aromatic reactions. The concept of nucleophilicity and electrophilicity will be discussed within the context of dative bonding and proton transfer of amines and alcohols. Pericyclic reactions cover the [4 + 2] or Diels-Alder cycloaddition, [2 + 2] cycloaddition, dipolar, and ene reactions. Examples include the reactions of alkenes, dienes, ketones, nitriles, and related multifunctional molecules at the interface. Aromaticity and the use of directing groups to influence the distribution of surface products will be illustrated with benzene, xylene, and heteroaromatic compounds. Finally, multifunctional molecules are used to describe the competition and selectively observed among different surface reactions. (C) 2003 Elsevier Ltd. All rights reserved.